Morphological and behavioral limit of visual resolution in temperate (Hippocampus abdominalis) and tropical (Hippocampus taeniopterus) seahorses.

PubMed

Lee, Hie Rin; O'Brien, Keely M Bumsted

2011-07-01

Seahorses are visually guided feeders that prey upon small fast-moving crustaceans. Seahorse habitats range from clear tropical to turbid temperate waters. How are seahorse retinae specialized to mediate vision in these diverse environments? Most species of seahorse have a specialization in their retina associated with acute vision, the fovea. The purpose of this study was to characterize the fovea of temperate Hippocampus abdominalis and tropical H. taeniopterus seahorses and to investigate their theoretical and behavioral limits of visual resolution. Their foveae were identified and photoreceptor (PR) and ganglion cell (GC) densities determined throughout the retina and topographically mapped. The theoretical limit of visual resolution was calculated using formulas taking into account lens radius and either cone PR or GC densities. Visual resolution was determined behaviorally using reactive distance. Both species possess a rod-free convexiclivate fovea. PR and GC densities were highest along the foveal slope, with a density decrease within the foveal center. Outside the fovea, there was a gradual density decrease towards the periphery. The theoretically calculated visual resolution on the foveal slope was poorer for H. abdominalis (5.25 min of arc) compared with H. taeniopterus (4.63 min of arc) based on PR density. Using GC density, H. abdominalis (9.81 min of arc) had a lower resolution compared with H. taeniopterus (9.04 min of arc). Behaviorally, H. abdominalis had a resolution limit of 1090.64 min of arc, while H. taeniopterus was much smaller, 692.86 min of arc. Although both species possess a fovea and the distribution of PR and GC is similar, H. taeniopterus has higher PR and GC densities on the foveal slope and better theoretical and behaviorally measured visual resolution compared to H. abdominalis. These data indicate that seahorses have a well-developed acute visual system, and tropical seahorses have higher visual resolution compared to temperate seahorses.

The role of selected soil fauna as predators of Apethymus abdominalis Lep. (Hymenoptera: Tenthredinidae) in oak forests in the District Caiuti, Romania

Treesearch

C. Ciornei; N. Popa; L. Ciuca; C. Rang

2003-01-01

The present study was initiated in 2001 in the oak forests from Trotus valley (Forest District Caiucti - Bacau, Romania) which were heavily infested by oak sawflies Apethymus abdominalis Lep. (Hymenoptera: Tenthredinidae), in order to understand better the role of soil-inhabitating predators in population regulation of this pest.

Morphology of brood pouch formation in the pot-bellied seahorse Hippocampus abdominalis.

PubMed

Kawaguchi, Mari; Okubo, Ryohei; Harada, Akari; Miyasaka, Kazuki; Takada, Kensuke; Hiroi, Junya; Yasumasu, Shigeki

2017-01-01

The reproductive strategies of vertebrates are diverse. Seahorses (Pisces: Syngnathidae) possess the unique characteristic of male pregnancy; i.e., males, not females, incubate embryos in a specialized structure called a 'brood pouch'. The brood pouch is formed along the ventral midline of the tail. The lumen of the brood pouch is surrounded by loose connective tissue, called pseudoplacenta, and dermis. We visualized and evaluated the morphology of brood pouch formation in Hippocampus abdominalis to gain generalizable insights into this process in seahorses. First, we employed several staining methods to characterize the pseudoplacenta and dermis of the brood pouch of mature male seahorses. The pseudoplacenta is composed mainly of reticular fibers, while the dermis is composed mainly of collagenous fibers. Further observations showed that pouch formation is initiated by linear projections of epithelia on both ventrolateral sides of the body. These projections elongated toward the ventral midline, eventually fused together, and then formed a baggy structure composed of a single dermis layer with neither smooth muscle nor pseudoplacenta. Finally, the pseudoplacenta was formed, together with two layers of dermis and smooth muscle. Thus, a fully developed brood pouch was established. The morphology of the luminal epithelium also changed during pouch formation. We analyzed the localization of C-type lectins as markers; haCTL II was localized in both the outer and luminal epithelia of the brood pouch throughout development in the male seahorse, whereas haCTL IV, which was not detected in the early stage of seahorse development, became localized only in the luminal epithelium as development proceeded. We categorized the processes of brood pouch formation during male seahorse development into three stages: (1) the early stage, characterized by formation of a baggy structure from the primordium; (2) the middle stage, characterized by the differentiation and establishment of brood pouch-specific tissues; and (3) the late stage, characterized by a fully formed pouch with developing blood vessels and a pouch fold ultimately capable of carrying and incubating embryos.

The impact of sex-role reversal on the diversity of the major histocompatibility complex: insights from the seahorse (Hippocampus abdominalis).

PubMed

Bahr, Angela; Wilson, Anthony B

2011-05-10

Both natural and sexual selection are thought to influence genetic diversity, but the study of the relative importance of these two factors on ecologically-relevant traits has traditionally focused on species with conventional sex-roles, with male-male competition and female-based mate choice. With its high variability and significance in both immune function and olfactory-mediated mate choice, the major histocompatibility complex (MHC/MH) is an ideal system in which to evaluate the relative contributions of these two selective forces to genetic diversity. Intrasexual competition and mate choice are both reversed in sex-role reversed species, and sex-related differences in the detection and use of MH-odor cues are expected to influence the intensity of sexual selection in such species. The seahorse, Hippocampus abdominalis, has an exceptionally highly developed form of male parental care, with female-female competition and male mate choice. Here, we demonstrate that the sex-role reversed seahorse has a single MH class II beta-chain gene and that the diversity of the seahorse MHIIβ locus and its pattern of variation are comparable to those detected in species with conventional sex roles. Despite the presence of only a single gene copy, intralocus MHIIβ allelic diversity in this species exceeds that observed in species with multiple copies of this locus. The MHIIβ locus of the seahorse exhibits a novel expression domain in the male brood pouch. The high variation found at the seahorse MHIIβ gene indicates that sex-role reversed species are capable of maintaining the high MHC diversity typical in most vertebrates.Whether such species have evolved the capacity to use MH-odor cues during mate choice is presently being investigated using mate choice experiments. If this possibility can be rejected, such systems would offer an exceptional opportunity to study the effects of natural selection in isolation, providing powerful comparative models for understanding the relative importance of selective factors in shaping patterns of genetic variation.

Evaluation of the internal oblique, external oblique, and transversus abdominalis muscles in patients with ankylosing spondylitis: an ultrasonographic study.

PubMed

Üşen, Ahmet; Kuran, Banu; Yılmaz, Figen; Aksu, Neşe; Erçalık, Cem

2017-11-01

The objectives of the study are to compare abdominal muscle thickness in ankylosing spondylitis (AS) patients with healthy subjects and determine the factors affecting these muscle thickness. Thirty-five male patients with a previous diagnosis of AS according to the Modified New York criteria and a control group consisting of 35 healthy male individuals were included in this cross-sectional and case-control study. Thicknesses of the internal oblique (IO), external oblique (EO), and transversus abdominalis (TrA) muscles were measured with ultrasound (US). AS patients were classified according to the International Physical Activity Questionnaire (IPAQ). There were 35 AS patients with a mean age of 35.17 ± 8.05 years and 35 healthy subjects with a mean age 32.57 ± 7.05 years. No significant difference was observed between the groups in terms of abdominal muscle thicknesses (p > 0.005). When the AS patients were classified according to the IPAQ scores, thicknesses of the IO and TrA muscles were significantly lower in patients who had the low level of IPAQ scores (p < 0.05). In the light of our first and preliminary results, muscle thickness of the IO, EO, and TrA muscles were similar in AS patients to healthy subjects. However, AS patients who had lower level of physical activity have also reduced thickness of IO and TrA muscles.

Frequency-dependent sexual selection.

PubMed

O'Donald, P; Majerus, M E

1988-07-06

Sexual selection by female choice is expected to give rise to a frequency-dependent sexual advantage in favour of preferred male phenotypes: the rarer the preferred phenotypes, the more often they are chosen as mates. This 'rare-male advantage' can maintain a polymorphism when two or more phenotypes are mated preferentially: each phenotype gains an advantage when it is rarer than the others; no preferred phenotype can then be lost from the population. Expression of preference may be complete or partial. In models of complete preference, females with a preference always mate preferentially. Models of partial preference are more realistic: in these models, the probability that a female mates preferentially depends on the frequency with which she encounters the males she prefers. Two different 'encounter models' of partial preference have been derived: the O'Donald model and the Charlesworth model. The encounter models contain the complete preference model as a limiting case. In this paper, the Charlesworth model is generalized to allow for female preference of more than one male phenotype. Levels of frequency dependence can then be compared in the O'Donald and Charlesworth models. The complete preference model and both encounter models are formulated in the same genetical terms of preferences for dominant and recessive male phenotypes. Polymorphic equilibria and conditions for stability are derived for each of the three models. The models are then fitted to data of frequencies of matings observed in experiments with the two-spot ladybird. The complete preference model gives as good a fit as the encounter models to the data of these and other experiments. The O'Donald and Charlesworth encounter models are shown to produce a very similar frequency-dependent relation. Generally, as females become less choosy, they express their preference with more dependence on male frequency, whereas the resulting selection of the males becomes less frequency dependent. More choosy females are more constant in expressing their preference, producing greater frequency dependence in the selection of the males.

Female guppies agree to differ: phenotypic and genetic variation in mate-choice behavior and the consequences for sexual selection.

PubMed

Brooks, R; Endler, J A

2001-08-01

Variation among females in mate choice may influence evolution by sexual selection. The genetic basis of this variation is of interest because the elaboration of mating preferences requires additive genetic variation in these traits. Here we measure the repeatability and heritability of two components of female choosiness (responsiveness and discrimination) and of female preference functions for the multiple ornaments borne by male guppies (Poecilia reticulata). We show that there is significant repeatable variation in both components of choosiness and in some preference functions but not in others. There appear to be several male ornaments that females find uniformly attractive and others for which females differ in preference. One consequence is that there is no universally attractive male phenotype. Only responsiveness shows significant additive genetic variation. Variation in responsiveness appears to mask variation in discrimination and some preference functions and may be the most biologically relevant source of phenotypic and genetic variation in mate-choice behavior. To test the potential evolutionary importance of the phenotypic variation in mate choice that we report, we estimated the opportunity for and the intensity of sexual selection under models of mate choice that excluded and that incorporated individual female variation. We then compared these estimates with estimates based on measured mating success. Incorporating individual variation in mate choice generally did not predict the outcome of sexual selection any better than models that ignored such variation.

Pair-bonded humans conform to sexual stereotypes in web-based advertisements for extra-marital partners.

PubMed

Kelley, Trish C; Hare, James F

2010-10-20

Partners advertisements provide advertisers with access to a large pool of prospective mates, and have proven useful in documenting sex differences in human mating preferences. We coded data from an Internet site (AshleyMadison.com) catering to advertisers engaged in existing pair-bonded relationships. While we predicted that pair-bonding may liberate advertisers from conforming to sexual stereotypes of male promiscuity and female choosiness, our results are uniformly consistent with those stereotypes. Our findings thus provide further evidence that human mating behavior is highly constrained by fundamental biological differences between males and females.

Bateman's principles and human sex roles.

PubMed

Brown, Gillian R; Laland, Kevin N; Mulder, Monique Borgerhoff

2009-06-01

In 1948, Angus J. Bateman reported a stronger relationship between mating and reproductive success in male fruit flies compared with females, and concluded that selection should universally favour 'an undiscriminating eagerness in the males and a discriminating passivity in the females' to obtain mates. The conventional view of promiscuous, undiscriminating males and coy, choosy females has also been applied to our own species. Here, we challenge the view that evolutionary theory prescribes stereotyped sex roles in human beings, firstly by reviewing Bateman's principles and recent sexual selection theory and, secondly, by examining data on mating behaviour and reproductive success in current and historic human populations. We argue that human mating strategies are unlikely to conform to a single universal pattern.

The impact of sex-role reversal on the diversity of the major histocompatibility complex: Insights from the seahorse (Hippocampus abdominalis)

PubMed Central

2011-01-01

Background Both natural and sexual selection are thought to influence genetic diversity, but the study of the relative importance of these two factors on ecologically-relevant traits has traditionally focused on species with conventional sex-roles, with male-male competition and female-based mate choice. With its high variability and significance in both immune function and olfactory-mediated mate choice, the major histocompatibility complex (MHC/MH) is an ideal system in which to evaluate the relative contributions of these two selective forces to genetic diversity. Intrasexual competition and mate choice are both reversed in sex-role reversed species, and sex-related differences in the detection and use of MH-odor cues are expected to influence the intensity of sexual selection in such species. The seahorse, Hippocampus abdominalis, has an exceptionally highly developed form of male parental care, with female-female competition and male mate choice. Results Here, we demonstrate that the sex-role reversed seahorse has a single MH class II beta-chain gene and that the diversity of the seahorse MHIIβ locus and its pattern of variation are comparable to those detected in species with conventional sex roles. Despite the presence of only a single gene copy, intralocus MHIIβ allelic diversity in this species exceeds that observed in species with multiple copies of this locus. The MHIIβ locus of the seahorse exhibits a novel expression domain in the male brood pouch. Conclusions The high variation found at the seahorse MHIIβ gene indicates that sex-role reversed species are capable of maintaining the high MHC diversity typical in most vertebrates. Whether such species have evolved the capacity to use MH-odor cues during mate choice is presently being investigated using mate choice experiments. If this possibility can be rejected, such systems would offer an exceptional opportunity to study the effects of natural selection in isolation, providing powerful comparative models for understanding the relative importance of selective factors in shaping patterns of genetic variation. PMID:21569286

Growth and stoichiometry of a common aquatic detritivore respond to changes in resource stoichiometry.

PubMed

Fuller, Chris L; Evans-White, Michelle A; Entrekin, Sally A

2015-03-01

Consumer growth determines the quantity of nutrients transferred through food webs. The extent to which leaf composition and consumer physiology interact to constrain consumer production is not well understood. For example, detritivore growth, and thus material transfer, could change with detrital elemental composition. Detrital type and associated microbial biofilms can mediate the amount and rate of detritus consumed and used towards growth. Detritivore body stoichiometry or the threshold elemental ratio, the food ratio resulting in optimal growth, may predict taxon-specific growth response to stoichiometrically-altered detritus. Empirical measures of detritivore growth responses across a range of detrital stoichiometry are rare. We fed a common detritivore, Tipula abdominalis, maple or oak leaves that spanned a gradient of carbon:phosphorus (C:P) to examine how leaf identity and C:P interact to influence growth, consumption, assimilation efficiencies, and post-assimilatory processes. Tipula abdominalis growth and consumption varied with leaf type and stoichiometry. Individuals fed oak grew faster and ate more compared to individuals fed maple. Individuals fed maple grew faster and ate more as leaf C:P decreased. All individuals lost most of the material they assimilated through respiration and excretion regardless of leaf type or leaf stoichiometry. Consumption and growth rates of T. abdominalis increased with maple nutrient enrichment, but not oak, indicating leaf-specific nutrient enrichment affected leaf palatability. Slightly non-homeostatic T. abdominalis C:P was maintained by varied consumption, carbon assimilation, and P excretion. Our study underlines the importance of how detritivore consumption and post-assimilatory processing could influence whole-stream material storage and nutrient cycling in detrital-based ecosystems.

Genotype-by-Environment Interactions for Female Mate Choice of Male Cuticular Hydrocarbons in Drosophila simulans

PubMed Central

Ingleby, Fiona C.; Hunt, John; Hosken, David J.

2013-01-01

Recent research has highlighted the potential importance of environmental and genotype-by-environment (G×E) variation in sexual selection, but most studies have focussed on the expression of male sexual traits. Consequently, our understanding of genetic variation for plasticity in female mate choice is extremely poor. In this study we examine the genetics of female mate choice in Drosophila simulans using isolines reared across two post-eclosion temperatures. There was evidence for G×Es in female choosiness and preference, which suggests that the evolution of female mate choice behaviour could differ across environments. However, the ranked order of preferred males was consistent across females and environments, so the same males are favoured by mate choice in spite of G×Es. Our study highlights the importance of taking cross-environment perspectives in order to gain a more comprehensive understanding of the operation of sexual selection. PMID:23825675

Surplus nest boxes and the potential for polygyny affect clutch size and offspring sex ratio in house wrens

PubMed Central

Dubois, Natalie S; Dale Kennedy, E; Getty, Thomas

2006-01-01

Females of many species can gain benefits from being choosy about their mates and even exhibit context-dependent investment in reproduction in response to the quality of their breeding situation. Here, we show that if a male house wren is provided with surplus nest boxes in his territory, his mate lays a larger clutch with a significantly higher proportion of sons. This response to a territory characteristic directly associated with male competitive ability, and ultimately to male reproductive success, suggests that male competition over access to high-quality territories with surplus nest boxes (i.e. those able to support polygyny) may influence female reproductive investment decisions. The results of this study have interesting implications, particularly considering the important role that studies of cavity nesting birds utilizing nest boxes have played in advancing our understanding of behaviour, ecology and evolution. PMID:16790407

Sexual display and mate choice in an energetically costly environment.

PubMed

Head, Megan L; Wong, Bob B M; Brooks, Robert

2010-12-09

Sexual displays and mate choice often take place under the same set of environmental conditions and, as a consequence, may be exposed to the same set of environmental constraints. Surprisingly, however, very few studies consider the effects of environmental costs on sexual displays and mate choice simultaneously. We conducted an experiment, manipulating water flow in large flume tanks, to examine how an energetically costly environment might affect the sexual display and mate choice behavior of male and female guppies, Poecilia reticulata. We found that male guppies performed fewer sexual displays and became less choosy, with respect to female size, in the presence of a water current compared to those tested in still water. In contrast to males, female responsive to male displays did not differ between the water current treatments and females exhibited no mate preferences with respect to male size or coloration in either treatment. The results of our study underscore the importance of considering the simultaneous effects of environmental costs on the sexual behaviors of both sexes.

Mate choice promotes inbreeding avoidance in the two-spotted spider mite.

PubMed

Tien, N S H; Massourakis, G; Sabelis, M W; Egas, M

2011-06-01

Since inbreeding in Tetranychus urticae can reduce offspring fitness, sexual selection may favour disassortative mate choice with respect to relatedness of the mating partners. We tested whether T. urticae shows this preference for mating with unrelated partners. We chose an experimental set-up with high potential for female choosiness, since females only mate once and are therefore expected to be the choosier gender. An adult virgin female was placed together with two adult males from the same population. One male was unrelated and the other male was related-a brother with whom she had grown up. Significantly more copulations (64%) took place with the unrelated male. Time to mating did not depend on the female-to-male relatedness. The remaining (non-copulating) male tried to interfere with the ongoing mating in the majority of cases, but this interference did not depend on the female-to-male relatedness. These results imply that T. urticae (a) can recognize kin (via genetic and/or environmental similarity) and (b) has the potential to avoid inbreeding through mate choice.

Mate choice and genetic monogamy in a biparental, colonial fish.

PubMed

Schaedelin, Franziska C; van Dongen, Wouter F D; Wagner, Richard H

2015-01-01

In socially monogamous species, in which both sexes provide essential parental care, males as well as females are expected to be choosy. Whereas hundreds of studies have examined monogamy in biparental birds, only several such studies exist in fish. We examined mate choice in the biparental, colonial cichlid fish Neolamprologus caudopunctatus in Lake Tanganyika, Zambia. We genotyped more than 350 individuals at 11 microsatellite loci to investigate their mating system. We found no extrapair paternity, identifying this biparental fish as genetically monogamous. Breeders paired randomly according to their genetic similarity, suggesting a lack of selection against inbreeding avoidance. We further found that breeders paired assortatively by body size, a criterion of quality in fish, suggesting mutual mate choice. In a subsequent mate preference test in an aquarium setup, females showed a strong preference for male size by laying eggs near the larger of 2 males in 13 of 14 trials.

Mate choice and genetic monogamy in a biparental, colonial fish

PubMed Central

van Dongen, Wouter F.D.; Wagner, Richard H.

2015-01-01

In socially monogamous species, in which both sexes provide essential parental care, males as well as females are expected to be choosy. Whereas hundreds of studies have examined monogamy in biparental birds, only several such studies exist in fish. We examined mate choice in the biparental, colonial cichlid fish Neolamprologus caudopunctatus in Lake Tanganyika, Zambia. We genotyped more than 350 individuals at 11 microsatellite loci to investigate their mating system. We found no extrapair paternity, identifying this biparental fish as genetically monogamous. Breeders paired randomly according to their genetic similarity, suggesting a lack of selection against inbreeding avoidance. We further found that breeders paired assortatively by body size, a criterion of quality in fish, suggesting mutual mate choice. In a subsequent mate preference test in an aquarium setup, females showed a strong preference for male size by laying eggs near the larger of 2 males in 13 of 14 trials. PMID:26023276

The complete mitochondrial genome of the big-belly seahorse, Hippocampus abdominalis (Lesson 1827).

PubMed

Wang, Lei; Chen, Zaizhong; Leng, Xiangjun; Gao, Jianzhong; Chen, Xiaowu; Li, Zhongpu; Sun, Peiying; Zhao, Yuming

2016-11-01

In this study, the complete mitogenome sequence of the big-belly seahorse, Hippocampus abdominalis (Lesson, 1827) (Syngnathiformes: Syngnathidae), has been sequenced by the next-generation sequencing method. The assembled mitogenome is 16 521 bp in length which includes 13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs genes. The overall base composition of the seahorse is 31.1% for A, 23.6% for C, 16.0% for G, 29.3% for T and shows 87% identities similar to tiger tail seahorse, Hippocampus comes. The complete mitogenome of the big-belly seahorse provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for seahorse family.

Sexy males and choosy females on exploded leks: correlates of male attractiveness in the Little Bustard.

PubMed

Jiguet, Frédéric; Bretagnolle, Vincent

2014-03-01

In their choice of mates, females may use alternative tactics, including a comparative assessment of males in a population, using one or several relative preference criteria. Traits involved in female choice should presumably be variable between, but not within males, thus potentially providing reliable cues of male identity and quality for prospecting females. In lekking species, sexual selection is usually intense, and females can freely choose mates. Studying the Little Bustard Tetrax tetrax, a bird with an exploded lek mating system, we first identified male phenotypic traits that showed higher among, than within variation (plumage pattern, display rates and call structure). Among those and other traits (ornaments and their symmetry, body condition, lek spatial organization and territory quality), we identified phenotypic traits that correlated with male attractiveness toward females. At least four phenotypic male traits were correlated with female attraction, i.e. body condition, lek attendance, ornamental symmetry and display rates. Traits related to the initial female attraction on male territory seem to differ from traits related to the decision of females to stay in the territory of attractive males. Copyright © 2014 Elsevier B.V. All rights reserved.

The Roles of Sexual and Viability Selection in the Evolution of Incomplete Reproductive Isolation: From Allopatry to Sympatry.

PubMed

Cotto, Olivier; Servedio, Maria R

2017-11-01

In recent years, theoretical models have introduced the concept that ongoing hybridization between "good" species can occur because incomplete reproductive isolation can be a selected optimum. They furthermore show that positive frequency-dependent sexual selection, which is naturally generated by some of the underlying processes that lead to assortative mating, plays a key role in the evolution of incomplete reproductive isolation. This occurs, however, through different mechanisms in sympatric versus allopatric scenarios. We investigate the evolution of incomplete reproductive isolation by sexual selection in scenarios ranging from sympatry to allopatry, to examine how these mechanisms interact. We consider an ecological scenario in which there are two habitats used during foraging and individuals can breed either within a habitat or in a common mating pool. We find that when trait divergence is maintained, sexual selection drives the evolution of choosiness in opposite ways in the common mating pool versus within each habitat. Specifically, strong choosiness is favored in the common mating pool, whereas intermediate choosiness is favored within habitat; the interaction of these forces determines whether intermediate reproductive isolation ultimately evolves in the system. We further find cases where the evolution of stronger choosiness occurs but leads to the loss of divergence. Overall, our study shows that contrasting forces on the evolution of reproductive isolation can occur in different mating areas, and we propose a new avenue for understanding the diversity in levels of reproductive isolation within and across species.

Phenotypic plasticity in sex pheromone production in Bicyclus anynana butterflies.

PubMed

Dion, Emilie; Monteiro, Antónia; Yew, Joanne Y

2016-12-14

Phenotypic plasticity refers to the environmental control of phenotypes. Cues experienced during development (developmental plasticity) or during adulthood (acclimatization) can both affect adult phenotypes. Phenotypic plasticity has been described in many traits but examples of developmental plasticity in physiological traits, in particular, remain scarce. We examined developmental plasticity and acclimatization in pheromone production in the butterfly Bicyclus anynana in response to rearing temperature. B. anynana lives in the African tropics where warm rearing temperatures of the wet season produce active males that court and females that choose, whereas cooler temperatures of the dry season lead to choosy less active males and courting females. We hypothesized that if male pheromone production is costly, it should be reduced in the dry season form. After describing the ultrastructure of pheromone producing cells, we showed that dry season males produced significantly less sex pheromones than wet season males, partly due to acclimatization and partly due to developmental plasticity. Variation in levels of one of the compounds is associated with differential regulation of a pheromone biosynthetic enzyme gene. This plasticity might be an adaptation to minimize pheromone production costs during the stressful dry season.

Shaking Youngsters and Shaken Adults: Female Beetles Eavesdrop on Larval Seed Vibrations to Make Egg-Laying Decisions

PubMed Central

Guedes, Raul Narciso C.; Yack, Jayne E.

2016-01-01

Egg-laying decisions are critical for insects, and particularly those competing for limited resources. Sensory information used by females to mediate egg-laying decisions has been reported to be primarily chemical, but the role of vibration has received little attention. We tested the hypothesis that vibrational cues produced by feeding larvae occupying a seed influences egg-laying decisions amongst female cowpea beetles. This hypothesis is supported by three lines of evidence using two strains of the cowpea beetle (Callosobruchus maculatus), an Indian strain with choosy females and aggressively competing larvae and a Brazilian strain with less choosy females and larvae exhibiting an “accommodating” type of competition. First, in free-choice bioassays of seed selection, choosy Indian females selected control seeds (free of eggs, larvae, or egg-laying marker) over seeds with live larvae (free of eggs and egg-laying marker), but did not discriminate between control seeds and those with dead larvae. In contrast, less choosy Brazilian females showed no preference for seeds containing live or dead larvae over controls. Second, laser-doppler vibrometer recordings confirmed that larvae feeding inside seeds generate vibrations that are available to the female during egg-laying decisions. Third, during dichotomous choice experiments where artificial vibrations approximating those produced by feeding larvae were played back during seed selection, Indian females preferred immobile control seeds over vibrating seeds, but Brazilian females showed no preference. These results support the hypothesis that females use larval vibrations in their egg-laying decisions; whether these vibrations are passive cues exploited by the female, or active signals that ‘steer’ the behaviour of the female is unknown. We propose that vibration cues and signals could be important for host selection in insects, particularly those laying on substrates where visual or chemical cues may be unreliable. This seems to be the case with females of the cowpea beetle since visual cues are not important and chemical egg-marking does not last more than two weeks, allowing vibration cues to improve discrimination of egg-laying substrate particularly by choosy females. PMID:26913508

The evolution of postpairing male mate choice.

PubMed

Lyu, Nan; Servedio, Maria R; Lloyd, Huw; Sun, Yue-Hua

2017-06-01

An increasing number of empirical studies in animals have demonstrated male mate choice. However, little is known about the evolution of postpairing male choice, specifically which occurs by differential allocation of male parental care in response to female signals. We use a population genetic model to examine whether such postpairing male mate choice can evolve when males face a trade-off between parental care and extra-pair copulations (EPCs). Specifically, we assume that males allocate more effort to providing parental care when mated to preferred (signaling) females, but they are then unable to allocate additional effort to seek EPCs. We find that both male preference and female signaling can evolve in this situation, under certain conditions. First, this evolution requires a relatively large difference in parental investment between males mated to preferred versus nonpreferred females. Second, whether male choice and female signaling alleles become fixed in a population versus cycle in their frequencies depends on the additional fecundity benefits from EPCs that are gained by choosy males. Third, less costly female signals enable both signaling and choice alleles to evolve under more relaxed conditions. Our results also provide a new insight into the evolution of sexual conflict over parental care. © 2017 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Effects of trunk stabilization exercise on the local muscle activity and balance ability of normal subjects.

PubMed

Cha, Hyun Gyu

2018-06-01

[Purpose] The purpose of this study was to investigate the effects of trunk stabilization exercise on the transvers abdominalis (TA) and internal oblique (IO) muscle activity and balance ability of normal subjects. [Subjects and Methods] Forty healthy male subjects without orthopedic history of the lower extremity were selected for the present study. The experimental group received a hollowing exercise, curl-up and bridging exercise. The control group received a pelvic tilting exercise in the sitting position for the same period of time. [Results] Significant differences in the post-training gains in Balance index, TA, IO were observed between the experimental group and the control group. [Conclusion] The trunk stabilization exercise improved the balance ability and increased the activity of the TA and IO muscle.

Diseases of captive yellow seahorse Hippocampus kuda Bleeker, pot-bellied seahorse Hippocampus abdominalis Lesson and weedy seadragon Phyllopteryx taeniolatus (Lacépède).

PubMed

LePage, V; Young, J; Dutton, C J; Crawshaw, G; Paré, J A; Kummrow, M; McLelland, D J; Huber, P; Young, K; Russell, S; Al-Hussinee, L; Lumsden, J S

2015-05-01

Seahorses, pipefish and seadragons are fish of the Family Syngnathidae. From 1998 to 2010, 172 syngnathid cases from the Toronto Zoo were submitted for post-mortem diagnostics and retrospectively examined. Among the submitted species were yellow seahorses Hippocampus kuda Bleeker (n=133), pot-bellied seahorses Hippocampus abdominalis Lesson (n=35) and weedy seadragons Phyllopteryx taeniolatus (Lacépède; n=4). The three most common causes of morbidity and mortality in this population were bacterial dermatitis, bilaterally symmetrical myopathy and mycobacteriosis, accounting for 24%, 17% and 15% of cases, respectively. Inflammatory processes were the most common diagnoses, present in 117 cases. Seven neoplasms were diagnosed, environmental aetiologies were identified in 46 cases, and two congenital defects were identified. © 2014 John Wiley & Sons Ltd.

THE EFFECT OF X-RAY IRRADIATION ON THE RESISTANCE OF WHITE MICE TO B. TYPHI ABDOMINALIS (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexeva, O.G.

1957-01-01

White mice were sensitized by intraperitoneal injection of 2.5 million B. typhi abdominalis Felix Ty/sub 2/ or 50 million B. dysenteria Flexner No. 26-w. Four days later they were subjected to total x-ray irradiation with a LD 10/13 dose (300 r). Experiments on 250 mice showed that in irradiated mice the biologic effect of a sensibilizing dose increases from DL 18/13 to DL 48/13 for typhus and from DL 3/13 to DL24/13 for dysentery. Mice sensitized with B. typhus abdominalis and irradiated died after periods typical for radiation sickness, but developed also bacteriemia pointing to a complicated pathologic process. Themore » degree of active antityphus immunization developed after sensibilization by the stated method was determined by intraperitoneal inoculation of 2 DCL (200 million) on the 1, 3, 5, 7, 10, 20, 30 day after irradiation with 300r. Experiments on 600 mice have shown that the earlier developed immunity does not change during the first days of radiation sickness. During the III period of radiation sickness (3-1Oth days) and in the reparation period (20--30th days) the survival of experimental mice is 40--45% less than of the unirradiated controls. The reduced tension of active immunity is also manifested by inhibition of phagocytosis in vivo, accumulation of enormous amounts of bacteria in the place of injection, and, protracted bacteriemia. (tr-auth)« less

Secondary compounds from exotic tree plantations change female mating preferences in the palmate newt (Lissotriton helveticus).

PubMed

Iglesias-Carrasco, M; Head, M L; Jennions, M D; Cabido, C

2017-10-01

Selection can favour phenotypic plasticity in mate choice in response to environmental factors that alter the costs and benefits of being choosy, or of choosing specific mates. Human-induced environmental change could alter sexual selection by affecting the costs of mate choice, or by impairing the ability of individuals to identify preferred mates. For example, variation in mate choice could be driven by environmentally induced differences in body condition (e.g. health) that change the cost of choosiness, or by environmental effects on the ability to detect or discriminate sexual signals. We teased apart these possibilities experimentally, by comparing female mate choice in the palmate newt Lissotriton helveticus between environments that mimic water from either native oak forests or exotic eucalypt plantations. In laboratory two-choice mate trials in clean water, females with prolonged exposure (21 days) to waterborne chemicals leached from eucalypt leaves did not preferentially associate with the male with a stronger immune response, but females exposed to water with chemicals from oak leaves did. In contrast, female choice was unaffected by the immediate presence or absence of eucalypt leachates during mate choice (using only females previously held in oak-treated water). The habitat-related change in female choice we observed is likely to be driven by effects of eucalypt leachates on female physiology, rather than immediate inhibition of pheromone transmission or blocking of pheromone reception. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Phenotypic plasticity in sex pheromone production in Bicyclus anynana butterflies

PubMed Central

Dion, Emilie; Monteiro, Antónia; Yew, Joanne Y.

2016-01-01

Phenotypic plasticity refers to the environmental control of phenotypes. Cues experienced during development (developmental plasticity) or during adulthood (acclimatization) can both affect adult phenotypes. Phenotypic plasticity has been described in many traits but examples of developmental plasticity in physiological traits, in particular, remain scarce. We examined developmental plasticity and acclimatization in pheromone production in the butterfly Bicyclus anynana in response to rearing temperature. B. anynana lives in the African tropics where warm rearing temperatures of the wet season produce active males that court and females that choose, whereas cooler temperatures of the dry season lead to choosy less active males and courting females. We hypothesized that if male pheromone production is costly, it should be reduced in the dry season form. After describing the ultrastructure of pheromone producing cells, we showed that dry season males produced significantly less sex pheromones than wet season males, partly due to acclimatization and partly due to developmental plasticity. Variation in levels of one of the compounds is associated with differential regulation of a pheromone biosynthetic enzyme gene. This plasticity might be an adaptation to minimize pheromone production costs during the stressful dry season. PMID:27966579

Sexual selection for male dominance reduces opportunities for female mate choice in the European bitterling (Rhodeus sericeus).

PubMed

Reichard, M; Bryja, J; Ondracková, M; Dávidová, M; Kaniewska, P; Smith, C

2005-04-01

Sexual selection involves two main mechanisms: intrasexual competition for mates and intersexual mate choice. We experimentally separated intrasexual (male-male interference competition) and intersexual (female choice) components of sexual selection in a freshwater fish, the European bitterling (Rhodeus sericeus). We compared the roles of multiple morphological and behavioural traits in male success in both components of sexual competition, and their relation to male reproductive success, measured as paternity of offspring. Body size was important for both female choice and male-male competition, though females also preferred males that courted more vigorously. However, dominant males often monopolized females regardless of female preference. Subordinate males were not excluded from reproduction and sired some offspring, possibly through sneaked ejaculations. Male dominance and a greater intensity of carotenoid-based red colouration in their iris were the best predictors of male reproductive success. The extent of red iris colouration and parasite load did not have significant effects on female choice, male dominance or male reproductive success. No effect of parasite load on the expression of red eye colouration was detected, though this may have been due to low parasite prevalence in males overall. In conclusion, we showed that even though larger body size was favoured in both intersexual and intrasexual selection, male-male interference competition reduced opportunities for female choice. Females, despite being choosy, had limited control over the paternity of their offspring. Our study highlights the need for reliable measures of male reproductive success in studies of sexual selection.

The pathogen transmission avoidance theory of sexual selection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loehle, C.

1997-08-01

The current theory that sexual selection results from female preference for males with good genes suffers from several problems. An alternative explanation, the pathogen transmission avoidance hypothesis, argues that the primary function of showy traits is to provide a reliable signal of current disease status, so that sick individuals can be avoided during mating. This study shows that a significant risk of pathogen transmission occurs during mating and that showy traits are reliable indicators of current disease status. The origin of female choosiness is argued to lie in a general tendency to avoid sick individuals, even in the absence ofmore » showy traits, which originate as exaggerations of normal traits that are indicative of good health (bright feathers, vigorous movement, large size). Thus, in this new model the origins of both showy traits and female choosiness are not problematic and there is no threshold effect. This model predicts that when the possession of male showy traits does not help to reduce disease in the female, showy traits are unlikely to occur. This case corresponds to thorough exposure of every animal to all group pathogens, on average, in large groups. Such species are shown with a large data set on birds to be less likely to exhibit showy traits. The good-genes model does not make this prediction. The pathogen transmission avoidance model can also lead to the evolution of showy traits even when selection is not effective against a given pathogen (e.g., when there is no heritable variation for resistance), but can result in selection for resistance if such genes are present. Monogamy is argued to reduce selection pressures for showy traits; data show monogamous species to be both less parasitized and less showy. In the context of reduction of pathogen transmission rates in showy populations, selection pressure becomes inversely frequency-dependent, which makes showy traits likely to be self-limiting rather than runaway.« less

Do Tetranychus urticae males avoid mating with familiar females?

PubMed

Yoshioka, T; Yano, S

2014-07-01

The two-spotted spider mite, Tetranychus urticae, usually lives in kin groups under common webs. Because only the first mating results in fertilisation in female T. urticae, adult males guard quiescent deutonymph females, those at the stage immediately before maturation, to ensure paternity. Therefore, the cost of precopulatory guarding time seems considerable for males. Moreover, the fitness indices of daughters from intra-population crosses were significantly lower than those of daughters from inter-population crosses, indicating that inbreeding depression exists in T. urticae. Therefore, we hypothesised that T. urticae males should be choosy in guarding familiar females to avoid inbreeding depression. Furthermore, webs should be a key element of the environment shared by familiar individuals. In this study, we demonstrated the inbreeding avoidance mechanism of T. urticae males in relation to webs produced by familiar females (known webs) or unfamiliar females (unknown webs). Regardless of surrounding webs (known or unknown), males preferred unfamiliar to familiar females. We further examined whether males detect unfamiliar females by their webs. When males had experienced a female's web without encountering that female, they subsequently preferred females that did not produce the surrounding webs in which the choice experiment was conducted. Results suggest that putative kin recognition for inbreeding avoidance in T. urticae males is based on the relationship between webs and females, and not on the discrimination of webs in shared environments. © 2014. Published by The Company of Biologists Ltd.

Meta-analysis suggests choosy females get sexy sons more than "good genes".

PubMed

Prokop, Zofia M; Michalczyk, Łukasz; Drobniak, Szymon M; Herdegen, Magdalena; Radwan, Jacek

2012-09-01

Female preferences for specific male phenotypes have been documented across a wide range of animal taxa, including numerous species where males contribute only gametes to offspring production. Yet, selective pressures maintaining such preferences are among the major unknowns of evolutionary biology. Theoretical studies suggest that preferences can evolve if they confer genetic benefits in terms of increased attractiveness of sons ("Fisherian" models) or overall fitness of offspring ("good genes" models). These two types of models predict, respectively, that male attractiveness is heritable and genetically correlated with fitness. In this meta-analysis, we draw general conclusions from over two decades worth of empirical studies testing these predictions (90 studies on 55 species in total). We found evidence for heritability of male attractiveness. However, attractiveness showed no association with traits directly associated with fitness (life-history traits). Interestingly, it did show a positive correlation with physiological traits, which include immunocompetence and condition. In conclusion, our results support "Fisherian" models of preference evolution, while providing equivocal evidence for "good genes." We pinpoint research directions that should stimulate progress in our understanding of the evolution of female choice. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Dark eyes in female sand gobies indicate readiness to spawn.

PubMed

Olsson, Karin H; Johansson, Sandra; Blom, Eva-Lotta; Lindström, Kai; Svensson, Ola; Nilsson Sköld, Helen; Kvarnemo, Charlotta

2017-01-01

In animals, colorful and conspicuous ornaments enhance individual attractiveness to potential mates, but are typically tempered by natural selection for crypsis and predator protection. In species where males compete for females, this can lead to highly ornamented males competing for mating opportunities with choosy females, and vice versa. However, even where males compete for mating opportunities, females may exhibit conspicuous displays. These female displays are often poorly understood and it may be unclear whether they declare mating intent, signal intrasexual aggression or form a target for male mate preference. We examined the function of the conspicuous dark eyes that female sand gobies temporarily display during courtship by experimentally testing if males preferred to associate with females with artificially darkened eyes and if dark eyes are displayed during female aggression. By observing interactions between a male and two females freely associating in an aquarium we also investigated in which context females naturally displayed dark eyes. We found that dark eyes were more likely to be displayed by more gravid females than less gravid females and possibly ahead of spawning, but that males did not respond behaviorally to dark eyes or prefer dark-eyed females. Females behaving aggressively did not display dark eyes. We suggest that dark eyes are not a signal per se but may be an aspect of female mate choice, possibly related to vision.

The trap of sex in social insects: from the female to the male perspective.

PubMed

Beani, Laura; Dessì-Fulgheri, Francesco; Cappa, Federico; Toth, Amy

2014-10-01

The phenotype of male Hymenoptera and the peculiar role of males has been neglected and greatly understudied, given the spectacular cooperative behavior of female social insects. In social insects there has been considerable progress in understanding the molecular mechanisms behind haplodiploid sex determination but, beyond that, very little is known concerning the neural, endocrine, and genetic correlates of sexual selection in males. An opportunity is being missed: the male phenotype in Hymenoptera is a natural experiment to compare the drives of natural versus sexual selection. In contrast to females, males do not work, they usually display far from the nest to gain mates, compete among rivals in nuptial flights or for a symbolic territory at leks, and engage in direct or ritualized conflicts. By comparing the available data on male paper wasps with studies on other social Hymenoptera, we summarize what we currently know about the physical, hormonal, neural and behavioral traits in a model system appropriate to examine current paradigms on sexual selection. Here we review male behavior in social Hymenoptera beyond sex stereotypes: the subtle role of "drones" in the colony, the lack of armaments and ornaments, the explosive mating crowds, the "endurance" race, the cognitive bases of the "choosy" male and his immune defense. Social insect males are not just simple-minded mating machines, they are shaped, constrained and perhaps trapped by sexual selection. Copyright © 2014 Elsevier Ltd. All rights reserved.

Males of a Strongly Polygynous Species Consume More Poisonous Food than Females

PubMed Central

Bravo, Carolina; Bautista, Luis Miguel; García-París, Mario; Blanco, Guillermo; Alonso, Juan Carlos

2014-01-01

We present evidence of a possible case of self-medication in a lekking bird, the great bustard Otis tarda. Great bustards consumed blister beetles (Meloidae), in spite of the fact that they contain cantharidin, a highly toxic compound that is lethal in moderate doses. In addition to anthelminthic properties, cantharidin was effective against gastrointestinal bacteria that cause sexually-transmitted diseases. Although both sexes consumed blister beetles during the mating season, only males selected them among all available insects, and ingested more and larger beetles than females. The male-biased consumption suggests that males could use cantharidin to reduce their parasite load and increase their sexual attractiveness. This plausibly explains the intense cloaca display males perform to approaching females, and the meticulous inspection females conduct of the male's cloaca, a behaviour only observed in this and another similar species of the bustard family. A white, clean cloaca with no infection symptoms (e.g., diarrhoea) is an honest signal of both, resistance to cantharidin and absence of parasites, and represents a reliable indicator of the male quality to the extremely choosy females. Our results do not definitely prove, but certainly strongly suggest that cantharidin, obtained by consumption of blister beetles, acts in great bustards as an oral anti-microbial and pathogen-limiting compound, and that males ingest these poisonous insects to increase their mating success, pointing out that self-medication might have been overlooked as a sexually-selected mechanism enhancing male fitness. PMID:25337911

Alternative Reproductive Tactics Arising from a Continuous Behavioral Trait: Callers versus Satellites in Field Crickets.

PubMed

Rotenberry, John T; Swanger, Elizabeth; Zuk, Marlene

2015-04-01

Alternative reproductive tactics may arise when natural enemies use sexual signals to locate the signaler. In field crickets, elevated costs to male calling due to acoustically orienting parasitoid flies create opportunity for an alternative tactic, satellite behavior, where noncalling males intercept females attracted to callers. Although the caller-satellite system in crickets that risk detection by parasitoids resembles distinct behavioral phenotypes, a male's propensity to behave as caller or satellite can be a continuously variable trait over several temporal scales, and an individual may pursue alternate tactics at different times. We modeled a caller-satellite-parasitoid system as a spatially explicit interaction among male and female crickets using individual-based simulation. Males varied in their propensity to call versus behave as a satellite from one night to the next. We varied mortality, density, sex ratio, and female mating behavior, and recorded lifetime number of mates as a function of a male's probability of calling (vs. acting as a satellite) along a gradient in parasitism risk. Frequently, the optimal behavior switched abruptly from being pure caller (call every night) to pure satellite (never call) as parasitism rate increased. However, mixed strategies prevailed even with high parasitism risk under conditions of higher background mortality rate, decreasing density, increasing female-biased sex ratio, and increasing female choosiness. In natural populations, high parasitoid pressure alone would be unlikely to yield fixation of pure satellite behavior.

On the role of individual differences in female odor and ultrasonic vocalizations for male's choice of partner.

PubMed

Snoeren, Eelke M; Helander, Lars R; Iversen, Eric E; Ågmo, Anders

2014-06-10

Intrasexual competition for access to a female mate is believed to be unusual in wild male rats, which suggests that female choosiness could be important. Even if competition is unusual, males still have to inevitably approach one partner first for copulation. In females, it has been shown that females spend longer time with one male compared to the others when tested in a multiple partner paradigm. The male mate preference was investigated in this study. In addition, the role of ultrasonic vocalizations (USVs) and female odors in the male's initial choice to approach one female instead of another was studied in this experiment. Male rats could choose between three different sexually receptive females. The experiment started with a 15-minute period with inaccessible females followed by a 15-minute period with accessible females in which the males could copulate with the females of his choice. The results showed that male rats spent more time with the female of 1st entry over the second or third females visited. No differences were found in USV subtype patterns emitted by the different females or the number of sniff episodes towards the different female chambers. Thus, the present experiments did not offer any evidence suggesting that USVs or individual differences in female odors play any role in male mate choice. Other factors that were not investigated in this study might be involved in male mate selection, but it should also be considered that mate selection could be random. Copyright © 2014 Elsevier Inc. All rights reserved.

Sexually dichromatic coloration reflects size and immunocompetence in female Spanish terrapins, Mauremys leprosa

NASA Astrophysics Data System (ADS)

Ibáñez, Alejandro; Marzal, Alfonso; López, Pilar; Martín, José

2013-12-01

Many studies have shown the importance of colorful ornamentation in mate choosiness or intrasexual conflict. However, research on color ornaments has focused mainly on birds, lizards or fish, but remains practically unknown in other animal groups such as turtles. In addition, female ornaments and their relation with sexual selection also remain almost unknown. Here, we measured the coloration of the shell and the limb stripes of male and female Spanish terrapins Mauremys leprosa and explored the existence of sexual dichromatism and the relation of color characteristics with body size and health state estimated from the immune response to the injection of an antigen (phytohaemagglutinin test). Our results showed that shell coloration, which could be constrained by natural selection to be cryptic, changed with body size, but did not differ between sexes. In contrast, females had brighter and less ultraviolet-saturated and more orange-saturated limb stripes than males. In females, interindividual variation in limb stripe coloration was related with body size and immune response suggesting that this coloration may inform honestly about multiple traits that could be important in sexual selection. In contrast, coloration of limb stripes of males was duller than in females, and was not related with any trait suggesting that coloration is not important in sexual selection for males.

Choosy but not chaste: multiple mating in human females.

PubMed

Scelza, Brooke A

2013-01-01

When Charles Darwin set out to relate his theory of evolution by natural selection to humans he discovered that a complementary explanation was needed to properly understand the great variation seen in human behavior. The resulting work, The Descent of Man and Selection in Relation to Sex, laid out the defining principles and evidence of sexual selection. In brief, this work is best known for illuminating the typically male strategy of intrasexual competition and the typically female response of intersexual choice. While these sexual stereotypes were first laid out by Darwin, they grew in importance when, years later, A. J. Bateman, in a careful study of Drosophila mating strategies, noted that multiple mating appeared to provide great benefit to male reproductive success, but to have no such effect on females. As a result, female choice soon became synonymous with being coy, and only males were thought to gain from promiscuous behavior. However, the last thirty years of research have served to question much of the traditional wisdom about sex differences proposed by Darwin and Bateman, illuminating the many ways that women (and females more generally) can and do engage in multiple mating. Copyright © 2013 Wiley Periodicals, Inc.

Exaggerated sexual swellings and male mate choice in primates: testing the reliable indicator hypothesis in the Amboseli baboons.

PubMed

Fitzpatrick, Courtney L; Altmann, Jeanne; Alberts, Susan C

2015-06-01

The paradigm of competitive males vying to influence female mate choice has been repeatedly upheld, but, increasingly, studies also report competitive females and choosy males. One female trait that is commonly proposed to influence male mate choice is the exaggerated sexual swelling displayed by females of many Old World primate species. The reliable indicator hypothesis posits that females use the exaggerated swellings to compete for access to mates, and that the swellings advertise variation in female fitness. We tested the two main predictions of this hypothesis in a wild population of baboons ( Papio cynocephalus) . First, we examined the effect of swelling size on the probability of mate-guarding ('consortship') by the highest-ranking male and the behavior of those males that trailed consorshipts ('follower males'). Second, we asked whether a female's swelling size predicted several fitness measures. We found that high-ranking males do not prefer females with larger swellings (when controlling for cycle number and conception) and that females with larger swellings did not have higher reproductive success. Our study-the only complete test of the reliable indicator hypothesis in a primate population-rejects the idea that female baboons compete for mates by advertising heritable fitness differences. Furthermore, we found unambiguous evidence that males biased their mating decisions in favor of females who had experienced more sexual cycles since their most recent pregnancy. Thus, rather than tracking the potential differences in fitness between females, male baboons appear to track and target the potential for a given reproductive opportunity to result in fertilization.

Personality differentially affects individual mate choice decisions in female and male Western mosquitofish (Gambusia affinis).

PubMed

Chen, Bo-Jian; Liu, Kai; Zhou, Lin-Jun; Gomes-Silva, Guilherme; Sommer-Trembo, Carolin; Plath, Martin

2018-01-01

Consistent individual differences in behavioral tendencies (animal personality) can affect individual mate choice decisions. We asked whether personality traits affect male and female mate choice decisions similarly and whether potential personality effects are consistent across different mate choice situations. Using western mosquitofish (Gambusia affinis) as our study organism, we characterized focal individuals (males and females) twice for boldness, activity, and sociability/shoaling and found high and significant behavioral repeatability. Additionally, each focal individual was tested in two different dichotomous mate choice tests in which it could choose between computer-animated stimulus fish of the opposite sex that differed in body size and activity levels, respectively. Personality had different effects on female and male mate choice: females that were larger than average showed stronger preferences for large-bodied males with increasing levels of boldness/activity (i.e., towards more proactive personality types). Males that were larger than average and had higher shoaling tendencies showed stronger preferences for actively swimming females. Size-dependent effects of personality on the strength of preferences for distinct phenotypes of potential mating partners may reflect effects of age/experience (especially in females) and social dominance (especially in males). Previous studies found evidence for assortative mate choice based on personality types or hypothesized the existence of behavioral syndromes of individuals' choosiness across mate choice criteria, possibly including other personality traits. Our present study exemplifies that far more complex patterns of personality-dependent mate choice can emerge in natural systems.

Enriching early adult environment affects the copulation behaviour of a tephritid fly.

PubMed

Díaz-Fleischer, Francisco; Arredondo, José; Aluja, Martín

2009-07-01

Early adult experiences in enriched environments favours animal brain and behavioural development ultimately resulting in an increased fitness. However, measuring the effect of environmental enrichment in animal behaviour in nature is often a complicated task, considering the complexity of the natural environment. We expanded previous studies to evaluate how early experience in an enriched environment affects copulation behaviour when animals are confronted with a complex semi-natural environment. Anastrepha ludens flies are an ideal model system for studying these effects because their natural habitats differ significantly from the cage environments in which these flies are reared for biological control purposes. For example, in the field, males form leks of up to six individuals. Each male defends a territory represented by a tree leaf whereas in rearing cages, territories are completely reduced because of the high population density. In a series of three experiments, we observed that male density represented the most influential stimulus for A. ludens male copulation success. Males that experienced lower densities in early adulthood obtained the highest proportion of copulations. By contrast, female copulation behaviour was not altered by female density. However, exposure to natural or artificial leaves in cages in which flies were kept until tested influenced female copulation behaviour. Females that were exposed to enriched environments exhibited a shorter latency to mate and shorter copulation durations with males than females reared in poor environments. We discuss the influence of early experience on male copulation success and female-mating choosiness.

Low reproductive skew despite high male-biased operational sex ratio in a glass frog with paternal care.

PubMed

Mangold, Alexandra; Trenkwalder, Katharina; Ringler, Max; Hödl, Walter; Ringler, Eva

2015-09-03

Reproductive skew, the uneven distribution of reproductive success among individuals, is a common feature of many animal populations. Several scenarios have been proposed to favour either high or low levels of reproductive skew. Particularly a male-biased operational sex ratio and the asynchronous arrival of females is expected to cause high variation in reproductive success among males. Recently it has been suggested that the type of benefits provided by males (fixed vs. dilutable) could also strongly impact individual mating patterns, and thereby affecting reproductive skew. We tested this hypothesis in Hyalinobatrachium valerioi, a Neotropical glass frog with prolonged breeding and paternal care. We monitored and genetically sampled a natural population in southwestern Costa Rica during the breeding season in 2012 and performed parentage analysis of adult frogs and tadpoles to investigate individual mating frequencies, possible mating preferences, and estimate reproductive skew in males and females. We identified a polygamous mating system, where high proportions of males (69 %) and females (94 %) reproduced successfully. The variance in male mating success could largely be attributed to differences in time spent calling at the reproductive site, but not to body size or relatedness. Female H. valerioi were not choosy and mated indiscriminately with available males. Our findings support the hypothesis that dilutable male benefits - such as parental care - can favour female polyandry and maintain low levels of reproductive skew among males within a population, even in the presence of direct male-male competition and a highly male-biased operational sex ratio. We hypothesize that low male reproductive skew might be a general characteristic in prolonged breeders with paternal care.

A revision of the Australian species of Lynceus Müller, 1776 (Crustacea: Branchiopoda: Laevicaudata, Lynceidae).

PubMed

Timms, Brian V

2013-01-01

Australia has had two species of Lynceus, L. macleayanus (King, 1855) and L. tatei (Brady, 1886) reported to date, both poorly described and without types, and supposedly both widely distributed. This study establishes neotypes and redescribes each according to modern standards. The present distribution of each is severely restricted by the destruction of temporary aquatic habitats, both in cities and in the country and also misunderstood by the lack of recent collecting in some outlying areas. Detailed study of male first thoracopods, together with an understanding of the form of the head and rostrum, antenna 2 spinal patterns, carapace shape, and the females' lamina abdominalis, most of which are discontinuously variable, has resulted in the delineation of four more species: L. baylyi sp. nov. in desert rockholes of Western Australia; L magdaleanae sp. nov. mainly in deep gnammas of the WA Wheatbelt and Goldfields but also extending into NT, Qld and SA; L. susanneae sp. nov. of rockholes on the Nullarbor Plain, WA; and L. argillaphilus sp. nov. of the coastal Pilbara, WA. Identification keys are provided for all six species, both males and females.

Female sexual arousal in amphibians.

PubMed

Wilczynski, Walter; Lynch, Kathleen S

2011-05-01

Rather than being a static, species specific trait, reproductive behavior in female amphibians is variable within an individual during the breeding season when females are capable of reproductive activity. Changes in receptivity coincide with changes in circulating estrogen. Estrogen is highest at the point when females are ready to choose a male and lay eggs. At this time female receptivity (her probability of responding to a male vocal signal) is highest and her selectivity among conspecific calls (measured by her probability of responding to a degraded or otherwise usually unattractive male signal) is lowest. These changes occur even though females retain the ability to discriminate different acoustic characteristics of various conspecific calls. After releasing her eggs, female amphibians quickly become less receptive and more choosy in terms of their responses to male sexual advertisement signals. Male vocal signals stimulate both behavior and estrogen changes in amphibian females making mating more probable. The changes in female reproductive behavior are the same as those generally accepted as indicative of a change in female sexual arousal leading to copulation. They are situationally triggered, gated by interactions with males, and decline with the consummation of sexual reproduction with a chosen male. The changes can be triggered by either internal physiological state or by the presence of stimuli presented by males, and the same stimuli change both behavior and physiological (endocrine) state in such a way as to make acceptance of a male more likely. Thus amphibian females demonstrate many of the same general characteristics of changing female sexual state that in mammals indicate sexual arousal. Copyright © 2010 Elsevier Inc. All rights reserved.

Exaggerated sexual swellings and male mate choice in primates: testing the reliable indicator hypothesis in the Amboseli baboons

PubMed Central

Fitzpatrick, Courtney L.; Altmann, Jeanne; Alberts, Susan C.

2015-01-01

The paradigm of competitive males vying to influence female mate choice has been repeatedly upheld, but, increasingly, studies also report competitive females and choosy males. One female trait that is commonly proposed to influence male mate choice is the exaggerated sexual swelling displayed by females of many Old World primate species. The reliable indicator hypothesis posits that females use the exaggerated swellings to compete for access to mates, and that the swellings advertise variation in female fitness. We tested the two main predictions of this hypothesis in a wild population of baboons (Papio cynocephalus). First, we examined the effect of swelling size on the probability of mate-guarding (‘consortship’) by the highest-ranking male and the behavior of those males that trailed consorshipts (‘follower males’). Second, we asked whether a female’s swelling size predicted several fitness measures. We found that high-ranking males do not prefer females with larger swellings (when controlling for cycle number and conception) and that females with larger swellings did not have higher reproductive success. Our study—the only complete test of the reliable indicator hypothesis in a primate population—rejects the idea that female baboons compete for mates by advertising heritable fitness differences. Furthermore, we found unambiguous evidence that males biased their mating decisions in favor of females who had experienced more sexual cycles since their most recent pregnancy. Thus, rather than tracking the potential differences in fitness between females, male baboons appear to track and target the potential for a given reproductive opportunity to result in fertilization. PMID:26752790

Physiological Costs of Repetitive Courtship Displays in Cockroaches Handicap Locomotor Performance

PubMed Central

Mowles, Sophie L.; Jepson, Natalie M.

2015-01-01

Courtship displays are typically thought to have evolved via female choice, whereby females select mates based on the characteristics of a display that is expected to honestly reflect some aspect of the male’s quality. Honesty is typically enforced by mechanistic costs and constraints that limit the level at which a display can be performed. It is becoming increasingly apparent that these costs may be energetic costs involved in the production of dynamic, often repetitive displays. A female attending to such a display may thus be assessing the physical fitness of a male as an index of his quality. Such assessment would provide information on his current physical quality as well as his ability to carry out other demanding activities, qualities with which a choosy female should want to provision her offspring. In the current study we use courtship interactions in the Cuban burrowing cockroach, Byrsotria fumigata to directly test whether courtship is associated with a signaler’s performance capacity. Males that had produced courtship displays achieved significantly lower speeds and distances in locomotor trials than non-courting control males. We also found that females mated more readily with males that produced a more vigorous display. Thus, males of this species have developed a strategy where they produce a demanding courtship display, while females choose males based on their ability to produce this display. Courtship displays in many taxa often involve dynamic repetitive actions and as such, signals of stamina in courtship may be more widespread than previously thought. PMID:26606147

Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae)

PubMed Central

2012-01-01

Background Members of the family Syngnathidae share a unique reproductive mode termed male pregnancy. Males carry eggs in specialised brooding structures for several weeks and release free-swimming offspring. Here we describe a systematic investigation of pre-release development in syngnathid fishes, reviewing available data for 17 species distributed across the family. This work is complemented by in-depth examinations of the straight-nosed pipefish Nerophis ophidion, the black-striped pipefish Syngnathus abaster, and the potbellied seahorse Hippocampus abdominalis. Results We propose a standardised classification of early syngnathid development that extends from the activation of the egg to the release of newborn. The classification consists of four developmental periods – early embryogenesis, eye development, snout formation, and juvenile – which are further divided into 11 stages. Stages are characterised by morphological traits that are easily visible in live and preserved specimens using incident-light microscopy. Conclusions Our classification is derived from examinations of species representing the full range of brooding-structure complexity found in the Syngnathidae, including tail-brooding as well as trunk-brooding species, which represent independent evolutionary lineages. We chose conspicuous common traits as diagnostic features of stages to allow for rapid and consistent staging of embryos and larvae across the entire family. In view of the growing interest in the biology of the Syngnathidae, we believe that the classification proposed here will prove useful for a wide range of studies on the unique reproductive biology of these male-brooding fish. PMID:23273265

Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae).

PubMed

Sommer, Stefan; Whittington, Camilla M; Wilson, Anthony B

2012-12-29

Members of the family Syngnathidae share a unique reproductive mode termed male pregnancy. Males carry eggs in specialised brooding structures for several weeks and release free-swimming offspring. Here we describe a systematic investigation of pre-release development in syngnathid fishes, reviewing available data for 17 species distributed across the family. This work is complemented by in-depth examinations of the straight-nosed pipefish Nerophis ophidion, the black-striped pipefish Syngnathus abaster, and the potbellied seahorse Hippocampus abdominalis. We propose a standardised classification of early syngnathid development that extends from the activation of the egg to the release of newborn. The classification consists of four developmental periods - early embryogenesis, eye development, snout formation, and juvenile - which are further divided into 11 stages. Stages are characterised by morphological traits that are easily visible in live and preserved specimens using incident-light microscopy. Our classification is derived from examinations of species representing the full range of brooding-structure complexity found in the Syngnathidae, including tail-brooding as well as trunk-brooding species, which represent independent evolutionary lineages. We chose conspicuous common traits as diagnostic features of stages to allow for rapid and consistent staging of embryos and larvae across the entire family. In view of the growing interest in the biology of the Syngnathidae, we believe that the classification proposed here will prove useful for a wide range of studies on the unique reproductive biology of these male-brooding fish.

Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy.

PubMed

Whittington, Camilla M; Griffith, Oliver W; Qi, Weihong; Thompson, Michael B; Wilson, Anthony B

2015-12-01

Viviparity (live birth) has evolved more than 150 times in vertebrates, and represents an excellent model system for studying the evolution of complex traits. There are at least 23 independent origins of viviparity in fishes, with syngnathid fishes (seahorses and pipefish) unique in exhibiting male pregnancy. Male seahorses and pipefish have evolved specialized brooding pouches that provide protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos. Pouch structures differ widely across the Syngnathidae, offering an ideal opportunity to study the evolution of reproductive complexity. However, the physiological and genetic changes facilitating male pregnancy are largely unknown. We used transcriptome profiling to examine pouch gene expression at successive gestational stages in a syngnathid with the most complex brood pouch morphology, the seahorse Hippocampus abdominalis. Using a unique time-calibrated RNA-seq data set including brood pouch at key stages of embryonic development, we identified transcriptional changes associated with brood pouch remodeling, nutrient and waste transport, gas exchange, osmoregulation, and immunological protection of developing embryos at conception, development and parturition. Key seahorse transcripts share homology with genes of reproductive function in pregnant mammals, reptiles, and other live-bearing fish, suggesting a common toolkit of genes regulating pregnancy in divergent evolutionary lineages. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Birds reveal their personality when singing.

PubMed

Garamszegi, László Zsolt; Eens, Marcel; Török, János

2008-07-09

Individual differences in social behaviour may have consequences for mate choice and sexual signalling, because partners should develop preferences for personalities that maximize reproductive output. Here we propose that behavioural traits involved in sexual advertisement may serve as good indicators of personality, which is fundamental for sexual selection to operate on temperament. Bird song has a prominent and well-established role in sexual selection, and it displays considerable variation among individuals with a potentially strong personality component. Therefore, we predicted that features of song would correlate with estimates of personality. In a field study of free-living male collared flycatchers, Ficedula albicollis, we characterised personality based on the exploration of an altered breeding environment, and based on the risk taken when a potential predator was approaching during a simulated territorial interaction. We found that explorative and risk-taker individuals consistently sang at lower song posts than shy individuals in the presence of a human observer. Moreover, males from lower posts established pair-bonds relatively faster than males from higher posts. Our results may demonstrate that risk taking during singing correlates with risk taking during aggression and with exploration, thus personality may be manifested in different contexts involving sexual advertisement. These findings are in accordance with the hypothesis that the male's balance between investment in reproduction and risk taking is reflected in sexual displays, and it may be important information for choosy females that seek partners with personality traits enhancing breeding success.

Evolution of frequency-dependent mate choice: keeping up with fashion trends

PubMed Central

Kokko, Hanna; Jennions, Michael D; Houde, Anne

2007-01-01

The diversity of sexual traits favoured by females is enormous and, curiously, includes preferences for males with rare or novel phenotypes. We modelled the evolution of a preference for rarity that yielded two surprising results. First, a Fisherian ‘sexy son’ effect can boost female preferences to a frequency well above that predicted by mutation–selection balance, even if there are significant mortality costs for females. Preferences do not reach fixation, however, as they are subject to frequency-dependent selection: if choosy females are too common, then rare genotypes in one generation become common, and thus unattractive, in the offspring generation. Nevertheless, even at relatively low frequency, preferences maintain polymorphism in male traits. The second unexpected result is that the preferences can evolve to much higher frequencies if choice is hindered, such that females cannot always express their preferences. Our results emphasize the need to consider feedback where preferences determine the dynamics of male genotypes and vice versa. They also highlight the similarity between the arbitrariness of behavioural norms in models of social evolution with punishment (the so-called ‘folk theorem’) and the diversity of sexual traits that can be preferred simply because deviating from the norm produces unattractive offspring and is, in this sense, ‘punished’. PMID:17360285

Genome size variation affects song attractiveness in grasshoppers: evidence for sexual selection against large genomes.

PubMed

Schielzeth, Holger; Streitner, Corinna; Lampe, Ulrike; Franzke, Alexandra; Reinhold, Klaus

2014-12-01

Genome size is largely uncorrelated to organismal complexity and adaptive scenarios. Genetic drift as well as intragenomic conflict have been put forward to explain this observation. We here study the impact of genome size on sexual attractiveness in the bow-winged grasshopper Chorthippus biguttulus. Grasshoppers show particularly large variation in genome size due to the high prevalence of supernumerary chromosomes that are considered (mildly) selfish, as evidenced by non-Mendelian inheritance and fitness costs if present in high numbers. We ranked male grasshoppers by song characteristics that are known to affect female preferences in this species and scored genome sizes of attractive and unattractive individuals from the extremes of this distribution. We find that attractive singers have significantly smaller genomes, demonstrating that genome size is reflected in male courtship songs and that females prefer songs of males with small genomes. Such a genome size dependent mate preference effectively selects against selfish genetic elements that tend to increase genome size. The data therefore provide a novel example of how sexual selection can reinforce natural selection and can act as an agent in an intragenomic arms race. Furthermore, our findings indicate an underappreciated route of how choosy females could gain indirect benefits. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Arrangement of Renal Arteries in Guinea Pig.

PubMed

Mazensky, David; Flesarova, Slavka

2017-03-01

The aim of this study was to describe origin, localization, and variations of renal arteries in guinea pig. The study was carried out on 26 adult guinea pigs. We prepared corrosion casts of the guinea pig arterial system. Batson's corrosion casting kit no. 17 was used as the casting medium. In 57.7% of specimens, a. renalis dextra was present as a single vessel with different level of its origin from aorta abdominalis. In 38.5% of specimens, two aa. renales dextrae were present with variable origin and arrangement. The presence of three aa. renales dextrae we found in one specimen. In 76.9% of specimens, a. renalis sinistra was present as a single vessel with different level of its origin from aorta abdominalis and variable arrangement. In 23.1% of specimens, we found two aa. renales sinistrae with variable origin and arrangement. The anatomical knowledge of the renal arteries, and its variations are of extreme importance for the surgeon that approaches the retroperitoneal region in several experiments, results of which are extrapolated in human. This is the first work dealing with the description of renal arteries arrangement in guinea pig. Anat Rec, 300:556-559, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Job shop fails choosy nurses.

PubMed

1993-10-13

Only 181 people have used the Clearing House set up to find jobs for redundant London nurses. And almost a quarter have rejected the posts which it says are suitable for them, with 21 per cent of employers turning down candidates selected by the initiative.

Predator experience overrides learned aversion to heterospecifics in stickleback species pairs

PubMed Central

Kozak, Genevieve M.; Boughman, Janette W.

2015-01-01

Predation risk can alter female mating decisions because the costs of mate searching and selecting attractive mates increase when predators are present. In response to predators, females have been found to plastically adjust mate preference within species, but little is known about how predators alter sexual isolation and hybridization among species. We tested the effects of predator exposure on sexual isolation between benthic and limnetic threespine sticklebacks (Gasterosteus spp.). Female discrimination against heterospecific mates was measured before and after females experienced a simulated attack by a trout predator or a control exposure to a harmless object. In the absence of predators, females showed increased aversion to heterospecifics over time. We found that predator exposure made females less discriminating and precluded this learned aversion to heterospecifics. Benthic and limnetic males differ in coloration, and predator exposure also affected sexual isolation by weakening female preferences for colourful males. Predator effects on sexual selection were also tested but predators had few effects on female choosiness among conspecific mates. Our results suggest that predation risk may disrupt the cognitive processes associated with mate choice and lead to fluctuations in the strength of sexual isolation between species. PMID:25808887

Mate choice screening in captive solitary carnivores: The role of male behavior and cues on mate preference and paternity in females of a model species, American mink (Neovison vison).

PubMed

Noer, Christina Lehmkuhl; Balsby, Thorsten Johannes Skovbjerg; Anistoroaei, Razvan; Stelvig, Mikkel; Dabelsteen, Torben

2017-12-01

Mate choice studies suggest that choosy females benefit from increased fecundity, litter size, and offspring survival. Thus, providing females with the opportunity to choose among potential mates, deemed genetically suitable based on studbook data, might improve breeding management in production and zoo animals and thereby the sustainability of captive populations. Investigating mate preference via odor from potential mates before animal transfer is a proposed strategy for incorporating mate choice into breeding management. In this study, we test whether olfactory cues and signals from males can be used to assess and measure female mate preference in American mink. Eighteen females were subjected to a 4-day stimulus test in which females showed a preference for one of two males' urine and feces. Subsequently, each female was subjected to a 10-day mate preference test involving the same two males of the first test. Paternity tests revealed that 13 females had offspring, which could be assigned to only one male, suggesting that these females performed a mate choice. In nine of these females preference during the stimulus test was directed toward the male that fathered their offspring. Our results suggest that even though there was a preference difference in scent stimulus trials from potential mates this preference was not predictive of eventual mate preference or paternity. Other factors such as aspects of male behavior seem to play a role, when the mates are introduced. Our study supports that mate preference and mate choice are complex matters influenced by multiple cues and signals. © 2017 Wiley Periodicals, Inc.

FRAMEWORK FOR ENVIRONMENTAL DECISION-MAKING, FRED: A TOOL FOR ENVIRONMENTALLY-PREFERABLE PURCHASING

EPA Science Inventory

In support of the Environmentally Preferable Purchasing Program of the US EPA, the Systems Analysis Branch has developed a decision-making tool based on life cycle assessment. This tool, the Framework for Responsible Environmental Decision-making or FRED streamlines LCA by choosi...

How important are direct fitness benefits of sexual selection?

NASA Astrophysics Data System (ADS)

Møller, A. P.; Jennions, M. D.

2001-10-01

Females may choose mates based on the expression of secondary sexual characters that signal direct, material fitness benefits or indirect, genetic fitness benefits. Genetic benefits are acquired in the generation subsequent to that in which mate choice is performed, and the maintenance of genetic variation in viability has been considered a theoretical problem. Consequently, the magnitude of indirect benefits has traditionally been considered to be small. Direct fitness benefits can be maintained without consideration of mechanisms sustaining genetic variability, and they have thus been equated with the default benefits acquired by choosy females. There is, however, still debate as to whether or not males should honestly advertise direct benefits such as their willingness to invest in parental care. We use meta-analysis to estimate the magnitude of direct fitness benefits in terms of fertility, fecundity and two measures of paternal care (feeding rate in birds, hatching rate in male guarding ectotherms) based on an extensive literature survey. The mean coefficients of determination weighted by sample size were 6.3%, 2.3%, 1.3% and 23.6%, respectively. This compares to a mean weighted coefficient of determination of 1.5% for genetic viability benefits in studies of sexual selection. Thus, for several fitness components, direct benefits are only slightly more important than indirect ones arising from female choice. Hatching rate in male guarding ectotherms was by far the most important direct fitness component, explaining almost a quarter of the variance. Our analysis also shows that male sexual advertisements do not always reliably signal direct fitness benefits.

Implementing a Nutrition and Physical Activity Curriculum in Head Start through an Academic-community Partnership

ERIC Educational Resources Information Center

Zahnd, Whitney E.; Smith, Tracey; Ryherd, Susan J.; Cleer, Melissa; Rogers, Valerie; Steward, David E.

2017-01-01

Background: Schools may be an effective avenue for interventions that prevent childhood obesity. "I am Moving I am Learning/Choosy Kids"© (IMIL/CK) is a curriculum recommended by Head Start (HS) for education in nutrition, physical activity, and healthy lifestyle habits. Methods: We formed an academic-community partnership (ACP), the…

Sexual signals and mating patterns in Syngnathidae.

PubMed

Rosenqvist, G; Berglund, A

2011-06-01

Male pregnancy in the family Syngnathidae (pipefishes, seahorses and seadragons) predisposes males to limit female reproductive success; sexual selection may then operate more strongly on females and female sexual signals may evolve (sex-role reversal). A bewildering array of female signals has evolved in Syngnathids, e.g. skin folds, large body size, colouration, markings on the body and elaborate courtship. These female sexual signals do not seem quantitatively or qualitatively different from those that evolve in males in species with conventional sex roles where males provide females or offspring with direct benefits. In several syngnathid species, males also evolve ornaments, females are choosy in addition to being competitive and males compete as well as choosing partners. Thus, sex roles form a continuum, spanning from conventional to reversed within this group of fishes. Cases are presented here suggesting that stronger sexual selection on females may be most extreme in species showing classical polyandry (one male mates with several females, such as many species where males brood their eggs on the trunk), intermediate in polygynandrous species (males and females both mate with more than one partner, as in many species where males brood their eggs on the tail) and least extreme, even exhibiting conventional sex roles, in monogamous species (one male mates solely with one female, as in many seahorses and tropical pipefishes). At the same time caution is needed before unanimously establishing this pattern: first, the connection between mating patterns, strength of sexual selection, sex roles and ornament expression is far from simple and straightforward, and second, knowledge of the actual morphology, ecology and behaviour of most syngnathid species is scanty. Basically only a few Nerophis, Syngnathus and Hippocampus species have been studied in any detail. It is known, however, that this group of fishes exhibits a remarkable variation in sex roles and ornamentation, making them an ideal group for the study of mating patterns, sexual selection and sexually selected signals. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

Borrow the Moon: The STFC Lunar Samples and Meteorites Loan Scheme

ERIC Educational Resources Information Center

Swift, Nick

2013-01-01

The Apollo missions brought back 382kg of Moon rock. The financial cost of getting these rocks was historically eye-watering so, understandably, NASA is choosy about who gets to play with them. Many go to scientists for laboratory investigation, but some have been set aside for loan to schools and the public. Luckily, the UK was allowed some,…

Relationship between caregivers' nutritional knowledge and children's dietary behavior in Chinese rural areas.

PubMed

Zeng, Rong; Luo, Jiayou; Tan, Cai; DU, Qiyun; Zhang, Weimin; Li, Yanping

2012-11-01

To explore the relationship between caregivers' nutritional knowledge and children's dietary behavior in rural areas of China. A cross-sectional study was conducted. 3361 rural caregivers and their children, aged 2 to 7 years old, were selected randomly and surveyed by questionnaire. Logistic regression models were used to identify the relationship between caregivers' nutritional knowledge and the children's dietary behaviors. The awareness level of nutritional knowledge among rural caregivers was 57.9%; among the children surveyed, 79.6% did not like to drink milk, 66.0% were considered choosy of food, 84.1% regularly snacked, 24.4% frequently skipped breakfast, and 13.7% did not come to meals on time. Logistic regression models indicated that a caregiver with a low level of nutritional knowledge is a risk factor for a child's unhealth dietary behaviors (snacking excepted): the odds ratios (OR) of not liking to drink milk, being choosy about food, skipping breakfast or not having meals on time are 1.665, 1.338, 1.330 and 1.582, respectively. Caregivers' nutritional knowledge is strongly associated with children's dietary behavior. Nutrition education programs are urgently wanted to improve caregiver's knowledge and thus to improve children's dietary behavior in rural areas of China.

Be a Choosy Chewer. Nutrition Comes Alive. Level 2. Nutrition Educator's Guide and Work Sheets, Letters to Parents, Recipes. Revised Edition.

ERIC Educational Resources Information Center

Thonney, Patricia; Mapes, Martha C.

This guide provides a nutrition education program for elementary school students that spans kindergarten through Grade 3 as well as providing activities for specific levels. Nutrition education objectives are stated for each grade level: (1) kindergarten--students will become familiar with and motivated to eat a variety of foods; (2) grade…

Sexual selection on female ornaments in the sex-role-reversed Gulf pipefish (Syngnathus scovelli).

PubMed

Flanagan, S P; Johnson, J B; Rose, E; Jones, A G

2014-11-01

Understanding how selection acts on traits individually and in combination is an important step in deciphering the mechanisms driving evolutionary change, but for most species, and especially those in which sexual selection acts more strongly on females than on males, we have no estimates of selection coefficients pertaining to the multivariate sexually selected phenotype. Here, we use a laboratory-based mesocosm experiment to quantify pre- and post-mating selection on female secondary sexual traits in the Gulf pipefish (Syngnathus scovelli), a sexually dimorphic, sex-role-reversed species in which ornamented females compete for access to choosy males. We calculate selection differentials and gradients on female traits, including ornament area, ornament number and body size for three episodes of selection related to female reproductive success (number of mates, number of eggs transferred and number of surviving embryos). Selection is strong on both ornament area and ornament size, and the majority of selection occurs during the premating episode of selection. Interestingly, selection on female body size, which has been detected in previous studies of Gulf pipefish, appears to be indirect, as evidenced by a multivariate analysis of selection gradients. Our results show that sexual selection favours either many bands or larger bands in female Gulf pipefish. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Characterization of a 1-cysteine peroxiredoxin from big-belly seahorse (Hippocampus abdominalis); insights into host antioxidant defense, molecular profiling and its expressional response to septic conditions.

PubMed

Godahewa, G I; Perera, N C N; Elvitigala, Don Anushka Sandaruwan; Jayasooriya, R G P T; Kim, Gi-Young; Lee, Jehee

2016-10-01

1-cysteine peroxiredoxin (Prx6) is an antioxidant enzyme that protects cells by detoxifying multiple peroxide species. This study aimed to describe molecular features, functional assessments and potential immune responses of Prx6 identified from the big-belly seahorse, Hippocampus abdominalis (HaPrx6). The complete ORF (666 bp) of HaPrx6 encodes a polypeptide (24 kDa) of 222 amino acids, and harbors a prominent peroxiredoxin super-family domain, a peroxidatic catalytic center, and a peroxidatic cysteine. The deduced amino acid sequence of HaPrx6 shares a relatively high amino acid sequence similarity and close evolutionary relationship with Oplegnathus fasciatus Prx6. The purified recombinant HaPrx6 protein (rHaPrx6) was shown to protect plasmid DNA in the Metal Catalyzed Oxidation (MCO) assay and, together with 1,4-Dithiothreitol (DTT), protected human leukemia THP-1 cells from extracellular H2O2-mediated cell death. In addition, quantitative real-time PCR revealed that HaPrx6 mRNA was constitutively expressed in 14 different tissues, with the highest expression observed in liver tissue. Inductive transcriptional responses were observed in liver and kidney tissues of fish after treating them with bacterial stimuli, including LPS, Edwardsiella tarda, and Streptococcus iniae. These results suggest that HaPrx6 may play an important role in the immune response of the big-belly seahorse against microbial infection. Collectively, these findings provide structural and functional insights into HaPrx6. Copyright © 2016 Elsevier Ltd. All rights reserved.

The evolution of phenotypes and genetic parameters under preferential mating

PubMed Central

Roff, Derek A; Fairbairn, Daphne J

2014-01-01

This article extends and adds more realism to Lande's analytical model for evolution under mate choice by using individual-based simulations in which females sample a finite number of males and the genetic architecture of the preference and preferred trait evolves. The simulations show that the equilibrium heritabilities of the preference and preferred trait and the genetic correlation between them (rG), depend critically on aspects of the mating system (the preference function, mode of mate choice, choosiness, and number of potential mates sampled), the presence or absence of natural selection on the preferred trait, and the initial genetic parameters. Under some parameter combinations, preferential mating increased the heritability of the preferred trait, providing a possible resolution for the lek paradox. The Kirkpatrick–Barton approximation for rG proved to be biased downward, but the realized genetic correlations were also low, generally <0.2. Such low values of rG indicate that coevolution of the preference and preferred trait is likely to be very slow and subject to significant stochastic variation. Lande's model accurately predicted the incidence of runaway selection in the simulations, except where preferences were relative and the preferred trait was subject to natural selection. In these cases, runaways were over- or underestimated, depending on the number of males sampled. We conclude that rapid coevolution of preferences and preferred traits is unlikely in natural populations, but that the parameter combinations most conducive to it are most likely to occur in lekking species. PMID:25077025

Convenience polyandry or convenience polygyny? Costly sex under female control in a promiscuous primate.

PubMed

Huchard, Elise; Canale, Cindy I; Le Gros, Chloé; Perret, Martine; Henry, Pierre-Yves; Kappeler, Peter M

2012-04-07

Classic sex roles depict females as choosy, but polyandry is widespread. Empirical attempts to understand the evolution of polyandry have often focused on its adaptive value to females, whereas 'convenience polyandry' might simply decrease the costs of sexual harassment. We tested whether constraint-free female strategies favour promiscuity over mating selectivity through an original experimental design. We investigated variation in mating behaviour in response to a reversible alteration of sexual dimorphism in body mass in the grey mouse lemur, a small primate where female brief sexual receptivity allows quantifying polyandry. We manipulated body condition in captive females, predicting that convenience polyandry would increase when females are weaker than males, thus less likely to resist their solicitations. Our results rather support the alternative hypothesis of 'adaptive polyandry': females in better condition are more polyandrous. Furthermore, we reveal that multiple mating incurs significant energetic costs, which are strikingly symmetrical between the sexes. Our study shows that mouse lemur females exert tight control over mating and actively seek multiple mates. The benefits of remating are nevertheless not offset by its costs in low-condition females, suggesting that polyandry is a flexible strategy yielding moderate fitness benefits in this small mammal.

Convenience polyandry or convenience polygyny? Costly sex under female control in a promiscuous primate

PubMed Central

Huchard, Elise; Canale, Cindy I.; Le Gros, Chloé; Perret, Martine; Henry, Pierre-Yves; Kappeler, Peter M.

2012-01-01

Classic sex roles depict females as choosy, but polyandry is widespread. Empirical attempts to understand the evolution of polyandry have often focused on its adaptive value to females, whereas ‘convenience polyandry’ might simply decrease the costs of sexual harassment. We tested whether constraint-free female strategies favour promiscuity over mating selectivity through an original experimental design. We investigated variation in mating behaviour in response to a reversible alteration of sexual dimorphism in body mass in the grey mouse lemur, a small primate where female brief sexual receptivity allows quantifying polyandry. We manipulated body condition in captive females, predicting that convenience polyandry would increase when females are weaker than males, thus less likely to resist their solicitations. Our results rather support the alternative hypothesis of ‘adaptive polyandry’: females in better condition are more polyandrous. Furthermore, we reveal that multiple mating incurs significant energetic costs, which are strikingly symmetrical between the sexes. Our study shows that mouse lemur females exert tight control over mating and actively seek multiple mates. The benefits of remating are nevertheless not offset by its costs in low-condition females, suggesting that polyandry is a flexible strategy yielding moderate fitness benefits in this small mammal. PMID:21976684

The Behavioral Type of a Top Predator Drives the Short-Term Dynamic of Intraguild Predation.

PubMed

Michalko, Radek; Pekár, Stano

2017-03-01

Variation in behavior among individual top predators (i.e., the behavioral type) can strongly shape pest suppression in intraguild predation (IGP). However, the effect of a top predator's behavioral type-namely, foraging aggressiveness (number of killed divided by prey time) and prey choosiness (preference degree for certain prey type)-on the dynamic of IGP may interact with the relative abundances of top predator, mesopredator, and pest. We investigated the influence of the top predator's behavioral type on the dynamic of IGP in a three-species system with a top predator spider, a mesopredator spider, and a psyllid pest using a simulation model. The model parameters were estimated from laboratory experiments and field observations. The top predator's behavioral type altered the food-web dynamics in a context-dependent manner. The system with an aggressive/nonchoosy top predator, without prey preferences between pest and mesopredator, suppressed the pest more when the top predator to mesopredator abundance ratio was high. In contrast, the system with a timid/choosy top predator that preferred the pest to the mesopredator was more effective when the ratio was low. Our results show that the behavioral types and abundances of interacting species need to be considered together when studying food-web dynamics, because they evidently interact. To improve biocontrol efficiency of predators, research on the alteration of their behavioral types is needed.

Resource quality or competition: why increase resource acceptance in the presence of conspecifics?

PubMed Central

Nufio, César R.; Papaj, Daniel R.

2011-01-01

Some animal species increase resource acceptance rates in the presence of conspecifics. Such responses may be adaptive if the presence of conspecifics is a reliable indicator of resource quality. Similarly, these responses could represent an adaptive reduction in choosiness under high levels of scramble competition. Although high resource quality and high levels of scramble competition should both favor increased resource acceptance, the contexts in which the increase occurs should differ. In this paper, we tested the effect of social environment on egg-laying and aggressive behavior in the walnut fly, Rhagoletis juglandis, in multiple contexts to determine whether increased resource acceptance in the presence of conspecifics was better viewed as a response to increased host quality or increased competition. We found that grouped females oviposit more readily than isolated females when provided small (low-quality) artificial hosts but not when provided large (high-quality) artificial hosts, indicating that conspecific presence reduces choosiness. Increased resource acceptance was observed even when exposure to conspecifics was temporally or spatially separate from exposure to the resource. Finally, we found that individuals showed reduced aggression after being housed in groups, as expected under high levels of scramble competition. These results indicate that the pattern of resource acceptance in the presence of conspecifics may be better viewed as a response to increased scramble competition rather than as a response to public information about resource quality. PMID:22479135

Resource quality or competition: why increase resource acceptance in the presence of conspecifics?

PubMed

Davis, Jeremy M; Nufio, César R; Papaj, Daniel R

2011-07-01

Some animal species increase resource acceptance rates in the presence of conspecifics. Such responses may be adaptive if the presence of conspecifics is a reliable indicator of resource quality. Similarly, these responses could represent an adaptive reduction in choosiness under high levels of scramble competition. Although high resource quality and high levels of scramble competition should both favor increased resource acceptance, the contexts in which the increase occurs should differ. In this paper, we tested the effect of social environment on egg-laying and aggressive behavior in the walnut fly, Rhagoletis juglandis, in multiple contexts to determine whether increased resource acceptance in the presence of conspecifics was better viewed as a response to increased host quality or increased competition. We found that grouped females oviposit more readily than isolated females when provided small (low-quality) artificial hosts but not when provided large (high-quality) artificial hosts, indicating that conspecific presence reduces choosiness. Increased resource acceptance was observed even when exposure to conspecifics was temporally or spatially separate from exposure to the resource. Finally, we found that individuals showed reduced aggression after being housed in groups, as expected under high levels of scramble competition. These results indicate that the pattern of resource acceptance in the presence of conspecifics may be better viewed as a response to increased scramble competition rather than as a response to public information about resource quality.

Strategic mating with common preferences.

PubMed

Alpern, Steve; Reyniers, Diane

2005-12-21

We present a two-sided search model in which individuals from two groups (males and females, employers and workers) would like to form a long-term relationship with a highly ranked individual of the other group, but are limited to individuals who they randomly encounter and to those who also accept them. This article extends the research program, begun in Alpern and Reyniers [1999. J. Theor. Biol. 198, 71-88], of providing a game theoretic analysis for the Kalick-Hamilton [1986. J. Personality Soc. Psychol. 51, 673-682] mating model in which a cohort of males and females of various 'fitness' or 'attractiveness' levels are randomly paired in successive periods and mate if they accept each other. Their model compared two acceptance rules chosen to represent homotypic (similarity) preferences and common (or 'type') preferences. Our earlier paper modeled the first kind by assuming that if a level x male mates with a level y female, both get utility -|x-y|, whereas this paper models the second kind by giving the male utility y and the female utility x. Our model can also be seen as a continuous generalization of the discrete fitness-level game of Johnstone [1997. Behav. Ecol. Sociobiol. 40, 51-59]. We establish the existence of equilibrium strategy pairs, give examples of multiple equilibria, and conditions guaranteeing uniqueness. In all equilibria individuals become less choosy over time, with high fitness individuals pairing off with each other first, leaving the rest to pair off later. This route to assortative mating was suggested by Parker [1983. Mate Choice, Cambridge University Press, Cambridge, pp. 141-164]. If the initial fitness distributions have atoms, then mixed strategy equilibria may also occur. If these distributions are unknown, there are equilibria in which only individuals in the same fitness band are mated, as in the steady-state model of MacNamara and Collins [1990. J. Appl. Prob. 28, 815-827] for the job search problem.

Molecular and functional characterization of caspase-8 from the big-belly seahorse (Hippocampus abdominalis).

PubMed

Oh, Minyoung; Elvitigala, Don Anushka Sandaruwan; Bathige, S D N K; Lee, Seongdo; Kim, Myoung-Jin; Lee, Jehee

2016-11-01

Apoptosis is a physiological process that can also participate in host immune defense mechanisms, including tumor growth suppression along with homeostasis and maturation of immune cells. Caspases are known to be involved in cellular apoptotic signaling; among them, caspase-8 plays an important role in the initiation phase of the apoptotic death cascade. In the current study, we molecularly characterized a caspase-8 homolog (designated as HaCasp-8) from Hippocampus abdominalis. The HaCasp-8 gene harbors a 1476 bp open reading frame (ORF) that codes for a protein of 492 amino acids (aa) with a predicted molecular mass of 55 kDa. HaCasp-8 houses the typical domain architecture of known initiator caspases, including the death effector domain and the carboxyl-terminal catalytic domain. As expected, phylogenetic analysis reflected a closer evolutionary relationship of HaCasp-8 with its teleostean similitudes. The results of our qPCR assays confirmed the ubiquitous expression of HaCasp-8 in physiologically important tissues examined, with pronounced expression levels in ovary tissues, followed by blood cells. HaCasp-8 expression at the mRNA level was found to be significantly modulated by lipopolysaccharide, polyinosinic:polycytidylic acid, Streptococcus iniae, and Edwardsiella tarda injection. Overexpression of HaCasp-8 could trigger a significant level of cell death in HEK293T cells, suggesting its putative role in cell death. Taken together, our findings suggest that HaCasp-8 is an important component in the caspase cascade, and its expression can be significantly modulated under pathogen stress conditions in the big-belly seahorse. Copyright © 2016 Elsevier Ltd. All rights reserved.

Manganese-superoxide dismutase (MnSOD), a role player in seahorse (Hippocampus abdominalis) antioxidant defense system and adaptive immune system.

PubMed

Perera, N C N; Godahewa, G I; Lee, Seongdo; Kim, Myoung-Jin; Hwang, Jee Youn; Kwon, Mun Gyeong; Hwang, Seong Don; Lee, Jehee

2017-09-01

Manganese superoxide dismutase (MnSOD) is a metaloenzyme that catalyzes dismutation of the hazardous superoxide radicals into less hazardous H 2 O 2 and H 2 O. Here, we identified a homolog of MnSOD from big belly seahorse (Hippocampus abdominalis; HaMnSOD) and characterized its structural and functional features. HaMnSOD transcript possessed an open reading frame (ORF) of 672 bp which codes for a peptide of 223 amino acids. Pairwise alignment showed that HaMnSOD shared highest identity with rock bream MnSOD. Results of the phylogenetic analysis of HaMnSOD revealed a close proximity with rock bream MnSOD which was consistent with the result of homology alignment. The intense expression of HaMnSOD was observed in the ovary, followed by the heart and the brain. Further, immune related responses of HaMnSOD towards pathogenic stimulation were observed through bacterial and viral challenges. Highest HaMnSOD expression in response to stimulants Edwardsiella tarda, Streptococcus iniae, lipopolysaccharide (LPS), and polyinosinic-polycytidylic acid (Poly I:C) was observed in the late stage in the blood tissue. Xanthine/xanthine oxidase assay (XOD assay) indicated the ROS-scavenging ability of purified recombinant HaMnSOD (rHaMnSOD). The optimum conditions for the SOD activity of rHaMnSOD were pH 9 and the 25 °C. Collectively, the results obtained through the expressional analysis profiles and the functional assays provide insights into potential immune related and antioxidant roles of HaMnSOD in the big belly seahorse. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification and molecular profiling of DC-SIGN-like from big belly seahorse (Hippocampus abdominalis) inferring its potential relevancy in host immunity.

PubMed

Jo, Eunyoung; Elvitigala, Don Anushka Sandaruwan; Wan, Qiang; Oh, Minyoung; Oh, Chulhong; Lee, Jehee

2017-12-01

Dendritic-cell-specific ICAM-3-grabbing non-integrin (DC-SIGN) is a C-type lectin that functions as a pattern recognition receptor by recognizing pathogen-associated molecular patterns (PAMPs). It is also involved in various events of the dendritic cell (DC) life cycle, such as DC migration, antigen capture and presentation, and T cell priming. In this study, a DC-SIGN-like gene from the big belly seahorse Hippocampus abdominalis (designated as ShDCS-like) was identified and molecularly characterized. The putative, complete ORF was found to be 1368 bp in length, encoding a protein of 462 amino acids with a molecular mass of 52.6 kDa and a theoretical isoelectric point of 8.26. The deduced amino acid sequence contains a single carbohydrate recognition domain (CRD), in which six conserved cysteine residues and two Ca 2+ -binding site motifs (QPN, WND) were identified. Based on pairwise sequence analysis, ShDCS-like exhibits the highest amino acid identity (94.6%) and similarity (97.4%) with DC-SIGN-like counterpart from tiger tail seahorse Hippocampus comes. Quantitative real-time PCR revealed that ShDCS-like mRNA is transcribed universally in all tissues examined, but with abundance in kidney and gill tissues. The basal mRNA expression of ShDCS-like was modulated in blood cell, kidney, gill and liver tissues in response to the stimulation of healthy fish with lipopolysaccharides (LPS), Edwardsiella tarda, or Streptococcus iniae. Moreover, recombinant ShDCS-like-CRD domain exhibited detectable agglutination activity against different bacteria. Collectively, these results suggest that ShDCS-like may potentially involve in immune function in big belly seahorses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Insights into the multifunctional role of natural killer enhancing factor-A (NKEF-A/Prx1) in big-belly seahorse (Hippocampus abdominalis): DNA protection, insulin reduction, H2O2 scavenging, and immune modulation activity.

PubMed

Godahewa, G I; Perera, N C N; Lee, Jehee

2018-02-05

Natural killer enhancing factor A (NKEF-A), also known as peroxiredoxin 1 (Prx1), is a well-known antioxidant involved in innate immunity. Although NKEF-A/Prx1 has been studied in different fish species, the present study broadens the knowledge of NKEF-A gene in terms of molecular structure, function, and immune responses in fish species. Hippocampus abdominalis NKEF-A (HaNKEF-A) cDNA encoded a putative protein of 198 amino acids containing a thioredoxin_2 domain, VCP motifs, and three conserved cysteine residues including peroxidatic and resolving cysteines. Amino acid sequence comparison and phylogenetic breakdown showed the higher sequence identity and closer evolutionary position of HaNKEF-A to those of other fish counterparts. A recombinant protein of HaNKEF-A was shown to i) protect supercoiled DNA against mixed catalyzed oxidation, ii) reduce insulin disulfide bonds, and iii) scavenge extracellular H 2 O 2 . Results of in vitro assays demonstrated the concentration dependent antioxidant function of recombinant HaNKEF-A. In addition, qPCR assessments revealed that the HaNKEF-A transcripts were constitutively expressed in fourteen tissues with the highest expression in liver. As an innate immune response, HaNKEF-A transcripts were up-regulated in liver post injection of LPS, Edwardsiella tarda, Streptococcus iniae, and polyinosinic-polycytidylic acid. Thus, HaNKEF-A can safeguards big-belly seahorse from oxidative damage and pathogenic infections. This study provides insight into the functions of NKEF-A/Prx1 in fish species. Copyright © 2017 Elsevier B.V. All rights reserved.

Men's strategic preferences for femininity in female faces.

PubMed

Little, Anthony C; Jones, Benedict C; Feinberg, David R; Perrett, David I

2014-08-01

Several evolutionarily relevant sources of individual differences in face preference have been documented for women. Here, we examine three such sources of individual variation in men's preference for female facial femininity: term of relationship, partnership status and self-perceived attractiveness. We show that men prefer more feminine female faces when rating for a short-term relationship and when they have a partner (Study 1). These variables were found to interact in a follow-up study (Study 2). Men who thought themselves attractive also preferred more feminized female faces for short-term relationships than men who thought themselves less attractive (Study 1 and Study 2). In women, similar findings for masculine preferences in male faces have been interpreted as adaptive. In men, such preferences potentially reflect that attractive males are able to compete for high-quality female partners in short-term contexts. When a man has secured a mate, the potential cost of being discovered may increase his choosiness regarding short-term partners relative to unpartnered men, who can better increase their short-term mating success by relaxing their standards. Such potentially strategic preferences imply that men also face trade-offs when choosing relatively masculine or feminine faced partners. In line with a trade-off, women with feminine faces were seen as more likely to be unfaithful and more likely to pursue short-term relationships (Study 3), suggesting that risk of cuckoldry is one factor that may limit men's preferences for femininity in women and could additionally lead to preferences for femininity in short-term mates. © 2013 The British Psychological Society.

Molecular characterization, transcriptional profiling, and antibacterial potential of G-type lysozyme from seahorse (Hippocampus abdominalis).

PubMed

Ko, Jiyeon; Wan, Qiang; Bathige, S D N K; Lee, Jehee

2016-11-01

Lysozymes are a family of enzymes that catalyze the hydrolysis of bacterial cell wall, acting as antimicrobial effectors of the innate immune system. In the present study, an ortholog of goose-type lysozyme (ShLysG) from the big-belly seahorse (Hippocampus abdominalis) was identified and characterized structurally and functionally. The full-length cDNA sequence (1213 bp) of ShLysG is comprised of an open reading frame made up of 552 bp, encoding a polypeptide of 184 amino acid (aa) with a predicted molecular mass of 20 kDa. In silico analysis of ShLysG revealed the absence of signal peptide and the presence of a characteristic bacterial soluble lytic transglycosylase (SLT) domain bearing three catalytic residues (Glu 71 , Asp 84 , and Asp 95 ) and seven N-acetyl-d-glucosamine binding sites (Glu 71 , Asp 95 , Tyr 98 , His 99 , Ile 117 , Tyr 145 , and Asn 146 ). Homology analysis demonstrated that the aa sequence of ShLysG shared 60.7-67.4% identity and 72.6-79.3% similarity with the orthologs of other teleosts. Phylogenetic analysis of ShLysG indicated a closest relationship with the ortholog from Gadus morhua. In healthy seahorse, ShLysG mRNA showed a constitutive expression in all the tissues examined, with the highest expression in kidney and the least expression in liver. The ShLysG mRNA levels were also shown significant elevation upon the bacterial and pathogen-associated molecular pattern (PAMPs) challenges. Furthermore, lytic activities of ShLysG recombinant protein were detected against several Gram-negative and Gram-positive bacterial species. Taken together, these results suggest that ShLysG might possess a potential immune defensive role against invading microbial pathogens in seahorse. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular cloning, biochemical characterization, and expression analysis of two glutathione S-transferase paralogs from the big-belly seahorse (Hippocampus abdominalis).

PubMed

Tharuka, M D Neranjan; Bathige, S D N K; Lee, Jehee

2017-12-01

Glutathione S-transferases (GSTs, EC 2.5.1.18) are important Phase II detoxifying enzymes that catalyze hydrophobic, electrophilic xenobiotic substance with the conjugation of reduced glutathione (GSH). In this study, GSTμ and GSTρ paralogs of GST in the big belly seahorse (Hippocampus abdominalis; HaGSTρ, HaGSTμ) were biochemically, molecularly, functionally characterized to determine their detoxification range and protective capacities upon different pathogenic stresses. HaGSTρ and HaGSTμ are composed of coding sequences of 681bp and 654bp, which encode proteins 225 and 217 amino acids, with predicted molecular masses of 26.06kDa and 25.74kDa respectively. Sequence analysis revealed that both HaGSTs comprise the characteristic GSH-binding site in the thioredoxin-like N-terminal domain and substrate binding site in the C-terminal domain. The recombinant HaGSTρ and HaGSTμ proteins catalyzed the model GST substrate 1-chloro-2, 4-dinitrobenzene (CDNB). Enzyme kinetic analysis revealed different K m and V max values for each rHaGST, suggesting that they have different conjugation rates. The optimum conditions (pH, temperature) and inhibitory assays of each protein demonstrated different optimal ranges. However, HaGSTμ was highly expressed in the ovary and gill, whereas HaGSTρ was highly expressed in the gill and pouch. mRNA expression of HaGSTρ and HaGSTμ was significantly elevated upon lipopolysaccharide, Poly (I:C), and Edwardsiella tarda challenges in liver and in blood cells as well as with Streptococcus iniae challenge in blood cells. From these collective experimental results, we propose that HaGSTρ and HaGSTμ are effective in detoxifying xenobiotic toxic agents, and importantly, their mRNA expression could be stimulated by immunological stress signals in the aquatic environment. Copyright © 2017 Elsevier Inc. All rights reserved.

First comparative characterization of three distinct ferritin subunits from a teleost: Evidence for immune-responsive mRNA expression and iron depriving activity of seahorse (Hippocampus abdominalis) ferritins.

PubMed

Oh, Minyoung; Umasuthan, Navaneethaiyer; Elvitigala, Don Anushka Sandaruwan; Wan, Qiang; Jo, Eunyoung; Ko, Jiyeon; Noh, Gyeong Eon; Shin, Sangok; Rho, Sum; Lee, Jehee

2016-02-01

Ferritins play an indispensable role in iron homeostasis through their iron-withholding function in living beings. In the current study, cDNA sequences of three distinct ferritin subunits, including a ferritin H, a ferritin M, and a ferritin L, were identified from big belly seahorse, Hippocampus abdominalis, and molecularly characterized. Complete coding sequences (CDS) of seahorse ferritin H (HaFerH), ferritin M (HaFerM), and ferritin L (HaFerL) subunits were comprised of 531, 528, and 522 base pairs (bp), respectively, which encode polypeptides of 177, 176, and 174 amino acids, respectively, with molecular masses of ∼20-21 kDa. Our in silico analyses demonstrate that these three ferritin subunits exhibit the typical characteristics of ferritin superfamily members including iron regulatory elements, domain signatures, and reactive centers. The coding sequences of HaFerH, M, and L were cloned and the corresponding proteins were overexpressed in a bacterial system. Recombinantly expressed HaFer proteins demonstrated detectable in vivo iron sequestrating (ferroxidase) activity, consistent with their putative iron binding capability. Quantification of the basal expression of these three HaFer sequences in selected tissues demonstrated a gene-specific ubiquitous spatial distribution pattern, with abundance of mRNA in HaFerM in the liver and predominant expression of HaFerH and HaFerL in blood. Interestingly, the basal expression of all three ferritin genes was found to be significantly modulated against pathogenic stress mounted by lipopolysaccharides (LPS), poly I:C, Streptococcus iniae, and Edwardsiella tarda. Collectively, our findings suggest that the three HaFer subunits may be involved in iron (II) homeostasis in big belly seahorse and that they are important in its host defense mechanisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Self-Perceived Mate Value, Facial Attractiveness, and Mate Preferences: Do Desirable Men Want It All?

PubMed

Arnocky, Steven

2018-01-01

Ten years ago, Buss and Shackelford demonstrated that high mate value (i.e., physically attractive) women held more discerning mate preferences relative to lower mate value women. Since then, researchers have begun to consider the equally important role of men's sexual selectivity in human mate choice. Yet, little research has focused on whether high mate value men are similarly choosy in their mate preferences. In a sample of 139 undergraduate men, relationships between self-perceived mate value as well as female-rated facial attractiveness were examined in relation to men's expressed mate preferences. Results showed that self-perceived mate value was unrelated to men's facial attractiveness as rated by women. Men who believed they were of high mate value were more likely than lower mate value men to prefer to marry at a younger age; to have a spouse who was younger than them; and to have a partner who was sociable, ambitious, high in social status, with good financial prospects, a desire for children, health, good looks, and mutual attraction. Objective male facial attractiveness was generally unrelated to heightened mate preferences, with the exception of heightened preference for similar religious background and good physical health. Findings suggest that men who perceive themselves as high in overall mate value are selective in their mate choice in a manner similar to high mate value women.

Sampling and assessment accuracy in mate choice: a random-walk model of information processing in mating decision.

PubMed

Castellano, Sergio; Cermelli, Paolo

2011-04-07

Mate choice depends on mating preferences and on the manner in which mate-quality information is acquired and used to make decisions. We present a model that describes how these two components of mating decision interact with each other during a comparative evaluation of prospective mates. The model, with its well-explored precedents in psychology and neurophysiology, assumes that decisions are made by the integration over time of noisy information until a stopping-rule criterion is reached. Due to this informational approach, the model builds a coherent theoretical framework for developing an integrated view of functions and mechanisms of mating decisions. From a functional point of view, the model allows us to investigate speed-accuracy tradeoffs in mating decision at both population and individual levels. It shows that, under strong time constraints, decision makers are expected to make fast and frugal decisions and to optimally trade off population-sampling accuracy (i.e. the number of sampled males) against individual-assessment accuracy (i.e. the time spent for evaluating each mate). From the proximate-mechanism point of view, the model makes testable predictions on the interactions of mating preferences and choosiness in different contexts and it might be of compelling empirical utility for a context-independent description of mating preference strength. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

NASA Astrophysics Data System (ADS)

Kiko, Rainer; Hauss, Helena; Buchholz, Friedrich; Melzner, Frank

2016-04-01

Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation - a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.

Genetic quality and sexual selection: an integrated framework for good genes and compatible genes.

PubMed

Neff, Bryan D; Pitcher, Trevor E

2005-01-01

Why are females so choosy when it comes to mating? This question has puzzled and marveled evolutionary and behavioral ecologists for decades. In mating systems in which males provide direct benefits to the female or her offspring, such as food or shelter, the answer seems straightforward--females should prefer to mate with males that are able to provide more resources. The answer is less clear in other mating systems in which males provide no resources (other than sperm) to females. Theoretical models that account for the evolution of mate choice in such nonresource-based mating systems require that females obtain a genetic benefit through increased offspring fitness from their choice. Empirical studies of nonresource-based mating systems that are characterized by strong female choice for males with elaborate sexual traits (like the large tail of peacocks) suggest that additive genetic benefits can explain only a small percentage of the variation in fitness. Other research on genetic benefits has examined nonadditive effects as another source of genetic variation in fitness and a potential benefit to female mate choice. In this paper, we review the sexual selection literature on genetic quality to address five objectives. First, we attempt to provide an integrated framework for discussing genetic quality. We propose that the term 'good gene' be used exclusively to refer to additive genetic variation in fitness, 'compatible gene' be used to refer to nonadditive genetic variation in fitness, and 'genetic quality' be defined as the sum of the two effects. Second, we review empirical approaches used to calculate the effect size of genetic quality and discuss these approaches in the context of measuring benefits from good genes, compatible genes and both types of genes. Third, we discuss biological mechanisms for acquiring and promoting offspring genetic quality and categorize these into three stages during breeding: (i) precopulatory (mate choice); (ii) postcopulatory, prefertilization (sperm utilization); and (iii) postcopulatory, postfertilization (differential investment). Fourth, we present a verbal model of the effect of good genes sexual selection and compatible genes sexual selection on population genetic variation in fitness, and discuss the potential trade-offs that might exist between mate choice for good genes and mate choice for compatible genes. Fifth, we discuss some future directions for research on genetic quality and sexual selection.

Linking behavioural syndromes and cognition: a behavioural ecology perspective.

PubMed

Sih, Andrew; Del Giudice, Marco

2012-10-05

With the exception of a few model species, individual differences in cognition remain relatively unstudied in non-human animals. One intriguing possibility is that variation in cognition is functionally related to variation in personality. Here, we review some examples and present hypotheses on relationships between personality (or behavioural syndromes) and individual differences in cognitive style. Our hypotheses are based largely on a connection between fast-slow behavioural types (BTs; e.g. boldness, aggressiveness, exploration tendency) and cognitive speed-accuracy trade-offs. We also discuss connections between BTs, cognition and ecologically important aspects of decision-making, including sampling, impulsivity, risk sensitivity and choosiness. Finally, we introduce the notion of cognition syndromes, and apply ideas from theories on adaptive behavioural syndromes to generate predictions on cognition syndromes.

Three new species of Ametadoria Townsend (Diptera: Tachinidae) from Area de Conservación Guanacaste, Costa Rica

PubMed Central

Wood, D. Monty; Smith, M. Alex; Hallwachs, Winnie; Janzen, Daniel

2015-01-01

Abstract We describe three new species in the genus Ametadoria Townsend from Area de Conservación Guanacaste (ACG), Costa Rica. All three were reared from wild-caught Zygaenidae and Lacturidae caterpillars. We provide a concise description of each species using morphology, life history and molecular data, with photographic documentation. The new species are authored and described by Fleming and Wood: Ametadoria karolramosae sp. nov., Ametadoria leticiamartinezae sp. nov., and Ametadoria mauriciogurdiani sp. nov. The following are proposed by Wood as new synonyms of Ametadoria Townsend: Adidyma Townsend syn. nov., and Abolodoria Townsend syn. nov. The following new combinations occur as a result of these new synonymies: Ametadoria abdominalis (Townsend) comb. nov., Ametadoria austrina (Coquillett) comb. nov., Ametadoria humilis (Wulp) comb. nov., Ametadoria misella (Wulp) comb. nov. Ametadoria adversa (Townsend) is proposed as a junior synonym of ​Ametadoria unispinosa Townsend, syn. nov​. PMID:26379458

Metabolism of Centropages species in the Mediterranean Sea and the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Gaudy, Raymond; Thibault-Botha, Delphine

2007-02-01

Information on the metabolism rates of Centropages typicus and congeneric species ( C. hamatus, C. furcatus, C. brachiatus and C. abdominalis) in neritic areas of the Mediterranean Sea, the North Atlantic Ocean and the Pacific Ocean are reported here. Respiration rates and excretion rates are strongly influenced by abiotic (i.e. temperature, salinity) and biotic factors (i.e. food availability and composition). Differences in the response of respiratory rates to temperature of acclimated, acclimatized and adapted individuals are clearly observed among regions of the Mediterranean Sea and the West and East shores of the Atlantic Ocean. Food supply also strongly affects respiration and excretion rates, as well as the size, sex and stage development of the individuals. The co-measurement of these two rates allows confirmation of the omnivory or carnivory oriented feeding habits of these species. The role of this neritic genus in coastal environment is also discussed.

[Autodermal plastics and transposition of musculus rectus abdominus for giant postoperative hernias].

PubMed

Ianov, V N

2000-01-01

For reduction of postoperative hernia relapses rate the technique of the autodermal plastics and transposition of musculus rectus abdominalis (MRA) was developed. This technique consists of two-sided transection of the lateral abdominal muscles (oblique and transverse) on the pararectal line, transposition of MRA together with their sheaths medially by autodermal continuous lacing to complete adaptation of the edges. Closing of the lateral muscle-aponeurotic defects was carried out with use of the double autodermal grafts which were prepared by Yanov's technique. This technique is indicated for giant postoperative hernias and pronounced diastase of the MRA in people with well developed abdominal muscles. This technique was used in 11 patients without complications after surgery. Long-term results are available for all the patients. The relapses were absent. The technique, developed by us, provides first of all restoration of physiological function of the MRA, and also closing of the abdominal wall muscle-aponeurotic defect.

Linking behavioural syndromes and cognition: a behavioural ecology perspective

PubMed Central

Sih, Andrew; Del Giudice, Marco

2012-01-01

With the exception of a few model species, individual differences in cognition remain relatively unstudied in non-human animals. One intriguing possibility is that variation in cognition is functionally related to variation in personality. Here, we review some examples and present hypotheses on relationships between personality (or behavioural syndromes) and individual differences in cognitive style. Our hypotheses are based largely on a connection between fast–slow behavioural types (BTs; e.g. boldness, aggressiveness, exploration tendency) and cognitive speed–accuracy trade-offs. We also discuss connections between BTs, cognition and ecologically important aspects of decision-making, including sampling, impulsivity, risk sensitivity and choosiness. Finally, we introduce the notion of cognition syndromes, and apply ideas from theories on adaptive behavioural syndromes to generate predictions on cognition syndromes. PMID:22927575

Diel changes in the near-surface biomass of zooplankton and the carbon content of vertical migrants

NASA Astrophysics Data System (ADS)

Hays, Graeme C.; Harris, Roger P.; Head, Robert N.

Zooplankton biomass and the carbon content of vertical migrants were measured in the NE Atlantic (36.5°N, 19.2°W) between 11 and 18 July 1996 as part of the Plankton Reactivity in the Marine Environment (PRIME) programme. The increase in zooplankton biomass near the surface (0-100 m) at night compared to during the day suggested that diel vertical migration was an important feature at this site. For three species of vertically migrant copepods, Pleuromamma pisekii, P. gracilis and P. abdominalis, the carbon content of individuals collected at dusk was significantly less than for individuals collected at dawn, with this reduction being 6.2, 7.3 and 14.8%, respectively. This dawn-dusk reduction in carbon content is consistent with the diel pattern of feeding and fasting exhibited by vertical migrants and supports the suggestion that migrating zooplankton will cause an active export of carbon from the surface layers.

Copper-zinc-superoxide dismutase (CuZnSOD), an antioxidant gene from seahorse (Hippocampus abdominalis); molecular cloning, sequence characterization, antioxidant activity and potential peroxidation function of its recombinant protein.

PubMed

Perera, N C N; Godahewa, G I; Lee, Jehee

2016-10-01

Copper-zinc-superoxide dismutase (CuZnSOD) from Hippocampus abdominalis (HaCuZnSOD) is a metalloenzyme which belongs to the ubiquitous family of SODs. Here, we determined the characteristic structural features of HaCuZnSOD, analyzed its evolutionary relationships, and identified its potential immune responses and biological functions in relation to antioxidant defense mechanisms in the seahorse. The gene had a 5' untranslated region (UTR) of 67 bp, a coding sequence of 465 bp and a 3' UTR of 313 bp. The putative peptide consists of 154 amino acids. HaCuZnSOD had a predicted molecular mass of 15.94 kDa and a theoretical pI value of 5.73, which is favorable for copper binding activity. In silico analysis revealed that HaCuZnSOD had a prominent Cu-Zn_superoxide_dismutase domain, two Cu/Zn signature sequences, a putative N-glycosylation site, and several active sites including Cu(2+) and Zn(2+) binding sites. The three dimensional structure indicated a β-sheet barrel with 8 β-sheets and two short α-helical regions. Multiple alignment analyses revealed many conserved regions and active sites among its orthologs. The highest amino acid identity to HaCuZnSOD was found in Siniperca chuatsi (87.4%), while Maylandia zebra shared a close relationship in the phylogenetic analysis. Functional assays were performed to assess the antioxidant, biophysical and biochemical properties of overexpressed recombinant (r) HaCuZnSOD. A xanthine/XOD assay gave optimum results at pH 9 and 25 °C indicating these may be the best conditions for its antioxidant action in the seahorse. An MTT assay and flow cytometry confirmed that rHaCuZnSOD showed peroxidase activity in the presence of HCO3(-). In all the functional assays, the level of antioxidant activity of rHaCuZnSOD was concentration dependent; metal ion supplementation also increased its activity. The highest mRNA expressional level of HaCuZnSOD was found in blood. Temporal assessment under pathological stress showed a delay response by HaCuZnSOD. Our findings demonstrated that HaCuZnSOD is an important antioxidant, which might be involved in the host antioxidant defense mechanism against oxidative stress. Copyright © 2016 Elsevier Ltd. All rights reserved.

Choosy Cannibals Preferentially Consume Siblings with Relatively Low Fitness Prospects.

PubMed

Dugas, Matthew B; McCormack, Larkin; Gadau, Alice; Martin, Ryan A

2016-07-01

When an individual can selfishly cannibalize a relative or altruistically set it free, the benefits of altruism will be positively associated with the relative's fitness prospects (the benefits it receives from altruism). We tested the prediction that altruism should be preferentially directed toward high-quality relatives using larvae of the New Mexican spadefoot toad (Spea multiplicata), a species in which tadpoles plastically express omnivore and carnivore ecomorphs. In a no-choice design, we presented carnivores with sibling or nonsibling omnivores varying in developmental stage, which is positively associated with survival in this toad's ephemeral larval environment. There was a significant interaction between relatedness and developmental stage on the probability of cannibalism: carnivores were overall more likely to cannibalize less developed omnivores, but this effect was exaggerated when the potential victim was a sibling. This evidence that altruists favor relatives with high fitness prospects highlights the numerous factors shaping altruism's payoffs.

Automated telemetry reveals age specific differences in flight duration and speed are driven by wind conditions in a migratory songbird.

PubMed

Mitchell, Greg W; Woodworth, Bradley K; Taylor, Philip D; Norris, D Ryan

2015-01-01

Given that winds encountered on migration could theoretically double or half the energy expenditure of aerial migrants, there should be strong selection on behaviour in relation to wind conditions aloft. However, evidence suggests that juvenile songbirds are less choosy about wind conditions at departure relative to adults, potentially increasing energy expenditure during flight. To date, there has yet to be a direct comparison of flight efficiency between free-living adult and juvenile songbirds during migration in relation to wind conditions aloft, likely because of the challenges of following known aged individual songbirds during flight. We used an automated digital telemetry array to compare the flight efficiency of adult and juvenile Savannah sparrows (Passerculus sandwichensis) as they flew nearly 100 km during two successive stages of their fall migration; a departure flight from their breeding grounds out over the ocean and then a migratory flight along a coast. Using a multilevel path modelling framework, we evaluated the effects of age, flight stage, tailwind component, and crosswind component on flight duration and groundspeed. We found that juveniles departed under wind conditions that were less supportive relative to adults and that this resulted in juveniles taking 1.4 times longer to complete the same flight trajectories as adults. We did not find an effect of age on flight duration or groundspeed after controlling for wind conditions aloft, suggesting that both age groups were flying at similar airspeeds. We also found that groundspeeds were 1.7 times faster along the coast than over the ocean given more favourable tailwinds along the coast and because birds appeared to be climbing in altitude over the ocean, diverting some energy from horizontal to vertical movement. Our results provide the first evidence that adult songbirds have considerably more efficient migratory flights than juveniles, and that this efficiency is driven by the selection of more supportive tailwind conditions aloft. We suggest that the tendency for juveniles to be less choosy about wind conditions at departure relative to adults could be adaptive if the benefits of having a more flexible departure schedule exceed the time and energy savings realized during flight with more supportive winds.

Neoplasia of captive yellow sea horses (Hippocampus kuda) and weedy sea dragons (Phyllopteryx taeniolatus).

PubMed

LePage, Véronique; Dutton, Christopher J; Kummrow, Maya; McLelland, David J; Young, Karrie; Lumsden, John S

2012-03-01

Syngnathidae is the family of fish that includes sea horses, pipefish, and sea dragons. To date, only a single publication has described neoplasia in syngnathids, a fibrosarcoma of the brood pouch in an aquarium-reared lined sea horse (Hippocampus erectus). From 1998 until 2010, the Toronto Zoo submitted 172 syngnathids for postmortem; species included the spotted or yellow sea horse (Hippocampus kuda), the pot-bellied sea horse (Hippocampus abdominalis) and the weedy sea dragon (Phyllopteryx taeniolatus). Seven neoplasms and two neoplastic-like lesions were identified from these cases. Under light microscopy, the neoplasms had morphological characteristics of a cardiac rhabdomyosarcoma, renal adenocarcinoma, renal adenoma, renal round cell tumors, which were likely lymphomas, exocrine pancreatic carcinoma, and intestinal carcinoma. Of these neoplasms, four had clear evidence of metastasis: the pancreatic and intestinal carcinomas and both round cell tumors. As syngnathids are highly fastidious animals, they can be difficult to maintain in captivity. In order to improve their husbandry, preventative and palliative care, as well as treatment, it is important to investigate and document the types of diseases affecting syngnathids.

The tripartite immune conflict in placentals and a hypothesis on fetal-->maternal microchimerism.

PubMed

Apari, Péter; Rózsa, Lajos

2009-01-01

There is a two-way traffic of immune cells through the placenta; and fetal immune cells are often present in the maternal body even long after giving birth. We present an adaptationist theory to interpret fetal-->maternal microchimerism and the diverse set of concomitant medical phenomena. We handle fetal, maternal, and paternal adaptive interests separately and in interaction with one another. Fetuses may benefit from immunological information gathered by migrant cells in the maternal body, and also from improved maternal defence. However, they may be jeopardized by a selfish maternal usage of fetal-->maternal microchimerism - i.e., some mothers get pregnant only to improve their immune system and then to abort. The use of microchimeric cells by the maternal immune system may contribute to the adaptive benefits of female choosiness and polyandry. While fathers may enjoy an indirect benefit from enhanced fetal and maternal health, they also face the risk of wasting sexual efforts due to selfish pregnancies of cheating females. Paternal alleles acting via clones of microchimeric cells in the maternal body could launch an immunological attack against the non-kin sperm in the female genitalia, or against the non-kin fetus in the womb. Furthermore, an intraspecific version of Zahavi's Mafia Hypothesis could explain a potential interaction between the abortion of fetuses and a subsequent rise of an autoimmune disease. We suggest that males may be capable to provoke microchimerism-induced autoimmune-like diseases in the mother in revenge of selfish pregnancies. This hypothetic paternal threat could increase the maternal costs associated to selfish pregnancies. From a medical point of view, we propose new interpretations for autoimmune-like diseases, infertility, miscarriage, and also for the prevailing connections among them. Specifically, we argue that miscarriages may cause autoimmune diseases, a reversed causality as compared to the currently accepted one.

Not all sex ratios are equal: the Fisher condition, parental care and sexual selection.

PubMed

Jennions, Michael D; Fromhage, Lutz

2017-09-19

The term 'sex roles' encapsulates male-female differences in mate searching, competitive traits that increase mating/fertilization opportunities, choosiness about mates and parental care. Theoretical models suggest that biased sex ratios drive the evolution of sex roles. To model sex role evolution, it is essential to note that in most sexually reproducing species (haplodiploid insects are an exception), each offspring has one father and one mother. Consequently, the total number of offspring produced by each sex is identical, so the mean number of offspring produced by individuals of each sex depends on the sex ratio (Fisher condition). Similarly, the total number of heterosexual matings is identical for each sex. On average, neither sex can mate nor breed more often when the sex ratio is even. But equally common in which sex ratio? The Fisher condition only applies to some reproductive measures (e.g. lifetime offspring production or matings) for certain sex ratios (e.g. operational or adult sex ratio; OSR, ASR). Here, we review recent models that clarify whether a biased OSR, ASR or sex ratio at maturation (MSR) have a causal or correlational relationship with the evolution of sex differences in parental care and competitive traits-two key components of sex roles. We suggest that it is more fruitful to understand the combined effect of the MSR and mortality rates while caring and competing than that of the ASR itself. In short, we argue that the ASR does not have a causal role in the evolution of parental care. We point out, however, that the ASR can be a cue for adaptive phenotypic plasticity in how each sex invests in parental care.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

Mechanosensitive neurons on the internal reproductive tract contribute to egg-laying-induced acetic acid attraction in Drosophila

PubMed Central

Gou, Bin; Liu, Ying; Guntur, Ananya R.; Stern, Ulrich; Yang, Chung-Hui

2014-01-01

Selecting a suitable site to deposit their eggs is an important reproductive need of Drosophila females. While their choosiness towards egg-laying sites is well documented, the specific neural mechanism that activates females’ search for attractive egg-laying sites is not known. Here we show that distention/contraction of females’ internal reproductive tract triggered by egg-delivery through the tract plays a critical role in activating such search. We found that females start to exhibit acetic acid attraction prior to depositing each egg but no attraction when they are not laying eggs. Artificially distending the reproductive tract triggers acetic acid attraction in non-egg-laying females whereas silencing the mechanosensitive neurons we identified that can sense the contractile status of the tract eliminates such attraction. Our work uncovers the circuit basis of an important reproductive need of Drosophila females and provides a simple model to dissect the neural mechanism that underlies a reproductive need-induced behavioral modification. PMID:25373900

Nectar quality perception by honey bees (Apis mellifera ligustica).

PubMed

Sanderson, Charlotte E; Cook, Peyton; Hill, Peggy S M; Orozco, Benjamin S; Abramson, Charles I; Wells, Harrington

2013-11-01

In exploring how foragers perceive rewards, we often find that well-motivated individuals are not too choosy and unmotivated individuals are unreliable and inconsistent. Nevertheless, when given a choice we see that individuals can clearly distinguish between rewards. Here we develop the logic of using responses to two-choice problems as a derivative function of perceived reward, and utilize this model to examine honey bee perception of nectar quality. Measuring the derivative allows us to deduce the perceived reward function. The derivative function of the perceived reward equation gives the rate of change of the reward perceived for each reward value. This approach depends on presenting free-flying foragers with a series of two different rewards presented simultaneously (i.e., two-choice, binomial tests). We also examine how honey bees integrate information from a range of reward qualities to formulate a functional response. Results suggest that honey bees overestimate higher quality rewards and that direct comparison is an important step in the integration of information from a range of rewards.

Protective effect of Shenfu injection preconditioning on lung ischemia-reperfusion injury

PubMed Central

Zhang, Hong; Wan, Zhanhai; Yan, Xiang; Wang, De-Gui; Leng, Yufang; Liu, Yongqiang; Zhang, Yan; Zhang, Haijun; Han, Xuena

2016-01-01

Lung ischemia-reperfusion injury remains a problem in thoracic surgery, as minimal progress has been made concerning its prevention and control. In the present study, the protective effects and the underlying mechanism of Shenfu injection preconditioning on a rat lung ischemia-reperfusion model was investigated. Shenfu injection is a well-known Chinese traditional medicine, which is composed of Red Radix Ginseng and Radix Aconitum carmichaelii, with ginseng saponin and aconitum alkaloids as the active ingredients. A total of 72 specific pathogen-free, healthy male Wistar rats were randomly divided into control, model and Shenfu injection (10 ml/kg injection prior to injury) groups and were assessed at the following points: Ischemia 45 min; reperfusion 60 min; and reperfusion 120 min. Blood collected from the aorta abdominalis was cryopreserved at −70°C for the analysis of malondialdehyde (MDA) and superoxide dismutase (SOD) activity. Lung tissues were divided into three equal sections in order to assess the wet-to-dry (W/D) lung ratio, tumor necrosis factor (TNF)-α expression levels, myeloperoxidase (MPO) activity, alveolar damage, total protein and hematoxylin and eosin staining. The results demonstrated that the lung W/D weight ratio, TNF-α expression levels and SOD activity in the Shenfu group were significantly lower at 120 min reperfusion (P<0.05), as compared with the model group. MPO and MDA activity significantly decreased following reperfusion at 60 and 120 min (P<0.05), as compared with the model group. In addition, the degree of alveolar damage in the Shenfu group was significantly decreased (P<0.05), as compared with the model group. In addition, compared with the model group, the degree of alveolar damage in the Shenfu group was significantly lower (P<0.05); however, no significant changes in total protein were observed. The extent of alveolar structural damage and the proportion of interstitial neutrophils and alveolar and interstitial red blood cells were lower in the Shenfu group, as compared with the model and control groups. Therefore, the results of the present study suggested that Shenfu injection may have protective effects on lung ischemia-reperfusion injury. PMID:27602083

Taxonomic revision of Stagmatoptera Burmeister, 1838 (Mantodea: Mantidae, Stagmatopterinae).

PubMed

Rodrigues, Henrique Miranda; Cancello, Eliana Marques

2016-11-01

Stagmatoptera Burmeister, 1838 includes medium to large-sized (49.8-98.7mm) praying mantises distributed in the Neotropical region. They are characterized for having a central, circular spot on each forewing, and 2-4 carinae in the head's frontal shield. This study is an updated revision of the genus on the basis of type and non-type material deposited in various scientific collections from Europe and the Americas. The following nomenclatural procedures were conducted: Stagmatoptera nova is a new junior synonym of Stagmatoptera pia, Stagmatoptera ignota as the junior synonym of Stagmatoptera femoralis, and Stagmatoptera flavipennis is reinstated as the junior synonym of Stagmatoptera supplicaria. Two new species are described: Stagmatoptera diana Rodrigues sp. n. from Colombia and Venezuela, and Stagmatoptera cerdai Rodrigues sp. n. from Trinidad & Tobago and Venezuela. Stagmatoptera now includes 14 species, two of which (Stagmatoptera abdominalis and Stagmatoptera indicator) are considered as species inquirenda. We provide detailed morphological descriptions of all species, a species-level identification key, in addition to abundant visual material to assist identification. Female genitalia, a structure seldom used for taxonomic purposes, was a useful character system to distinguish among species of the genus. Distribution maps for all species are also provided.

Choosy Moral Punishers

PubMed Central

Clavien, Christine; Tanner, Colby J.; Clément, Fabrice; Chapuisat, Michel

2012-01-01

The punishment of social misconduct is a powerful mechanism for stabilizing high levels of cooperation among unrelated individuals. It is regularly assumed that humans have a universal disposition to punish social norm violators, which is sometimes labelled “universal structure of human morality” or “pure aversion to social betrayal”. Here we present evidence that, contrary to this hypothesis, the propensity to punish a moral norm violator varies among participants with different career trajectories. In anonymous real-life conditions, future teachers punished a talented but immoral young violinist: they voted against her in an important music competition when they had been informed of her previous blatant misconduct toward fellow violin students. In contrast, future police officers and high school students did not punish. This variation among socio-professional categories indicates that the punishment of norm violators is not entirely explained by an aversion to social betrayal. We suggest that context specificity plays an important role in normative behaviour; people seem inclined to enforce social norms only in situations that are familiar, relevant for their social category, and possibly strategically advantageous. PMID:22720012

Towards a richer evolutionary game theory

PubMed Central

McNamara, John M.

2013-01-01

Most examples of the application of evolutionary game theory to problems in biology involve highly simplified models. I contend that it is time to move on and include much more richness in models. In particular, more thought needs to be given to the importance of (i) between-individual variation; (ii) the interaction between individuals, and hence the process by which decisions are reached; (iii) the ecological and life-history context of the situation; (iv) the traits that are under selection, and (v) the underlying psychological mechanisms that lead to behaviour. I give examples where including variation between individuals fundamentally changes predicted outcomes of a game. Variation also selects for real-time responses, again resulting in changed outcomes. Variation can select for other traits, such as choosiness and social sensitivity. More generally, many problems involve coevolution of more than one trait. I identify situations where a reductionist approach, in which a game is isolated from is ecological setting, can be misleading. I also highlight the need to consider flexibility of behaviour, mental states and other issues concerned with the evolution of mechanism. PMID:23966616

Abdominal wall sinus due to impacting gallstone during laparoscopic cholecystectomy: an unusual complication.

PubMed

Pavlidis, T E; Papaziogas, B T; Koutelidakis, I M; Papaziogas, T B

2002-02-01

During laparoscopic cholecystectomy, perforation of the gallbladder can occurs in < or = 20% of cases, while gallstone spillage occurs in < or = 6% of cases. In most cases, there are no consequences. Gallstones can be lost in the abdominal wall as well as the abdomen during extraction of the gallbladder. The fate of such lost gallstones, which can lead to the formation of an abscess, an abdominal wall mass, or a persistent sinus, has not been studied adequately. Herein we report the case of a persistent sinus of the abdominal wall after an emergent laparoscopic cholecystectomy in an 82-year-old woman with gangrenous cholecystitis and perforation of the friable wall in association with an empyema of the gallbladder. The culture of the obtained pus was positive for Escherichia coli. After a small leak of dirty fluid from the wound of the epigastric port site of 4 months' duration, surgical exploration under local anesthesia revealed that the sinus was caused by spilled gallstones impacting into the abdominal wall between the posterior sheath and left rectus abdominalis muscle. The removal of the stones resulted in complete healing. Long-term complications after laparoscopic cholecystectomy involving the abdominal wall are rare but important possible consequences that could be avoided.

Two distinct CXC chemokine receptors (CXCR3 and CXCR4) from the big-belly seahorse Hippocampus abdominalis: Molecular perspectives and immune defensive role upon pathogenic stress.

PubMed

Priyathilaka, Thanthrige Thiunuwan; Oh, Minyoung; Bathige, S D N K; De Zoysa, Mahanama; Lee, Jehee

2017-06-01

CXC chemokine receptor 3 (CXCR3) and 4 (CXCR4) are members of the seven transmembrane G protein coupled receptor family, involved in pivotal physiological functions. In this study, seahorse CXCR3 and CXCR4 (designated as HaCXCR3 and HaCXCR4) cDNA sequences were identified from the transcriptome library and subsequently molecularly characterized. HaCXCR3 and HaCXCR4 encoded 363 and 373 amino acid long polypeptides, respectively. The HaCXCR3 and HaCXCR4 deduced proteins have typical structural features of chemokine receptors, including seven transmembrane domains and a G protein coupled receptors family 1 profile with characteristic DRY motifs. Amino acid sequence comparison and phylogenetic analysis of these two CXC chemokine receptors revealed a close relationship to their corresponding teleost counterparts. Quantitative real time PCR analysis revealed that HaCXCR3 and HaCXCR4 were ubiquitously expressed in all the tested tissues, with highest expression levels in blood cells. The seahorse blood cells and kidney HaCXCR3 and HaCXCR4 mRNA expressions were differently modulated when challenged with Edwardsiella tarda, Streptococcus iniae, lipopolysaccharide, and polyinosinic:polycytidylic acid, confirming their involvement in post immune responses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shallot Aphids, Myzus ascalonicus, in Strawberry: Biocontrol Potential of Three Predators and Three Parasitoids

PubMed Central

Enkegaard, Annie; Sigsgaard, Lene; Kristensen, Kristian

2013-01-01

The parasitization capacity of 3 parasitoids and the predation capacity of 3 predators towards the shallot aphid, Myzus ascalonicus Doncaster (Homoptera: Aphididae), on strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae) cv. Honeoye, were examined in laboratory experiments. In Petri dish assays, both Aphidius colemani Viereck (Hymenoptera: Aphidiidae) and A. ervi Haliday readily stung shallot aphids, with no significant difference in stinging frequency between the two species. A. ervi induced a significantly higher mortality (79.0 ± 7.2%) in terms of stung aphids compared with A. colemani (55.3 ± 4.1%); however, only a minor fraction (2.7 ± 1.8% and 7.1 ± 3.1%, respectively) of the killed aphids resulted in formation of mummies, presumably due to a physiological response to parasitism. The low percentage of mummification precludes the use of either Aphidius species in anything but inundative biocontrol. In similar set-ups, Aphelinus abdominalis (Dalman) (Hymenoptera: Aphelinidae) killed almost half (49.6 ± 5.3%) of the exposed aphids through host feeding. In addition, 23.2 ± 7.3% of non-host-fed aphids developed into mummified aphids, and 38.1 ± 13.2% of non-host-fed aphids died from other parasitoid-induced causes. However, the host feeding rate was reduced to only 1.2 ± 0.8%, and no significant parasitization mortality was observed on strawberry plants, suggesting that host plants interfered with A. abdominalis activity. This parasitoid does not, therefore, seem to be suited to either inoculative or inundative biocontrol of shallot aphids in strawberry. The three predators studied were the green lacewing, Chrysoperla carnea Steph. (Neuroptera: Chrysopidae), the two-spotted lady beetle, Adalia bipunctata L. (Coleoptera: Coccinellidae), and the gall midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). Third instars of all 3 predators readily preyed upon the shallot aphid in Petri dish set-ups with significant differences in daily predation (34.62 ± 3.45, 25.25 ± 3.18, and 13.34 ± 1.45, respectively). Further studies on A. bipunctata revealed that the larvae maintained their daily predation capacity (32.0 ± 6.3) on strawberry plants. About 60% of already ovipositing A. bipunctata refrained from laying any eggs on the first day after transfer to set-ups with combinations of shallot or peach-potato aphids, Myzus persicae (Sulzer) (Homoptera: Aphididae), and strawberry or sweet pepper leaves. The aphid species and the plant species did not, however, have a significant influence on the number of females laying eggs, the average number of eggs laid during the first day being 6.37±1.28 per female. Adult lady beetles had a significant preference for odor from controls without plants over odors from uninfested strawberry or pepper plants, but they showed no preference for either of the plant species, whether infested with aphids or not. The predation capacity of A. bipunctata on shallot aphids holds promise for its use in inundative biocontrol, and the results on egg laying cues suggests that inoculative biocontrol may be possible, although further studies will be needed for a complete evaluation. PMID:24224712

A taxonomic revision of the subfamily Tillinae Leach sensu lato (Coleoptera, Cleridae) in the New World

PubMed Central

Burke, Alan; Zolnerowich, Gregory

2017-01-01

Abstract The subfamily Tillinae Leach is represented by 12 genera in the New World. In this study, eight of these genera are revised. A diagnosis and redescription of the species of Araeodontia Barr, Barrotillus Rifkind, Bogcia Barr, Cylidrus Latreille, Cymatoderella Barr, Lecontella Wolcott & Chapin, Monophylla Spinola, and Onychotillus Chapin are presented. Bogcia oaxacae Barr is designated as a junior synonym of Bogcia disjuncta Barr. One species, Cymatodera striatopunctata Chevrolat, is transferred to Lecontella. The following species are redescribed: Araeodontia isabellae (Wolcott), A. marginalis Barr, A. peninsularis (Schaeffer), Barrotillus kropotkini Rifkind, Bogcia disjuncta Barr, Cylidrus abdominalis Klug, Cymatoderella collaris (Spinola), C. morula Rifkind, C. patagoniae (Knull), Lecontella brunnea (Spinola), L. gnara Wolcott, L. striatopunctata (Chevrolat), Monophylla californica (Fall), M. pallipes Schaeffer, M. terminata (Say), Onychotillus vittatus Chapin, and O. cubana De Zayas. Transcriptions of the original descriptions of Araeodontia picipennis Barr, Bostrichoclerus bicornis Van Dyke and Monophylla cinctipennis (Chevrolat) are given. Cymatodera Gray, with approximately 130 described species, is excluded from this study due to the number of species involved. The genera Neocallotillus Burke and Callotillus Wolcott are also excluded here since these groups have been recently revised elsewhere. Collection data are provided for all species revised. Updated distribution maps are presented. Keys to New World genera and species are given and taxonomic characters of relevant importance are provided and discussed. PMID:29290697

Copepod community succession during warm season in Lagoon Notoro-ko, northeastern Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Nakagawa, Yoshizumi; Ichikawa, Hideaki; Kitamura, Mitsuaki; Nishino, Yasuto; Taniguchi, Akira

2015-06-01

Lagoon Notoro-ko, located on the northeastern coast of Hokkaido, Japan, and connected to the Okhotsk Sea by a human-made channel, is strongly influenced by local hydrography, as water masses in the lagoon are seasonally influenced by the Soya Warm Current and the East Sakhalin Current. We here report on the succession of copepod communities during the warm season in relation to water mass exchange. Copepods were categorized into four seasonal communities (spring/early-summer, mid-summer, late-summer/fall, and early-winter) via a cluster analysis based on Bray-Curtis similarities. Spring/early-summer and early-winter communities were characterized by the temperate-boreal calanoid Pseudocalanus newmani, comprising 34.9%-77.6% of the total abundance of copepods during times of low temperature/salinity, as influenced by the prevailing East Sakhalin Current. Late-summer/fall communities were characterized by the neritic warm-water calanoid Paracalanus parvus s.l., comprising 63.9%-96.3% of the total abundance, as influenced by the Soya Warm Current. Mid-summer communities comprised approximately equal abundances of P. parvus, Eurytemora herdmani, Scolecithricella minor, and Centropages abdominalis (12.8%-28.2%); this community is transitional between those of the spring/early-summer and late-summer/fall. Copepod community succession in Lagoon Notoro-ko can be largely explained by seasonal changes in water masses.

Implementing a Nutrition and Physical Activity Curriculum in Head Start Through an Academic-Community Partnership.

PubMed

Zahnd, Whitney E; Smith, Tracey; Ryherd, Susan J; Cleer, Melissa; Rogers, Valerie; Steward, David E

2017-06-01

Schools may be an effective avenue for interventions that prevent childhood obesity. I am Moving I am Learning/Choosy Kids © (IMIL/CK) is a curriculum recommended by Head Start (HS) for education in nutrition, physical activity, and healthy lifestyle habits. We formed an academic-community partnership (ACP), the Springfield Collaborative for Active Child Health, to promote prevention of childhood obesity, in part, to implement the IMIL/CK curriculum in local HS sites. The ACP included a medical school, HS program, public school district, and state health department. Community-based participatory research principles helped identify and organize important implementation activities: community engagement, curriculum support, professional teacher training, and evaluation. IMIL/CK was piloted in 1 school then implemented in all local HS sites. All sites were engaged in IMIL/CK professional teacher training, classroom curriculum delivery, and child physical activity assessments. Local HS policy changed to include IMIL/CK in lesson plans and additional avenues of collaboration were initiated. Furthermore, improvements in physical activity and/or maintenance or improvement of healthy weight prevalence was seen in 4 of the 5 years evaluated. An ACP is an effective vehicle to implement and evaluate childhood obesity prevention programming in HS sites. © 2017, American School Health Association.

The effect of previous experience on trap construction and movement distance in a pit-building predator.

PubMed

Adar, Shay; Scharf, Inon; Dor, Roi

2016-10-01

Wormlion larvae are sit-and-wait predators that construct cone-shaped pits in sandy patches to capture prey. Wormlions select microhabitats that feature favorable conditions for pit construction, in a similar way to other trap-building predators, like spiders and antlions. We investigated whether wormlions exhibit an experience-based behavioral plasticity in their pit construction behavior. In a laboratory experiment, pit sizes and relocation distances were compared between larvae that experienced either a period of unfavorable conditions, i.e., surface obstacles, shallow or coarse sand, or a period of favorable conditions, i.e., clear, deep, and fine sand and were able to construct pits undisturbed. We expected that wormlions experiencing improving conditions would build larger pits than those experiencing deteriorating conditions. In addition, we expected that larvae experiencing unfavorable conditions would be less choosy in their new microhabitat and move over shorter distances. We observed a certain effect of recent experience on the trap-building behavior; however, it was not consistent among treatments. Additionally, we detected a correlation between larval body mass, relocation distance, and pit area. These findings might suggest that past experience does not influence wormlion foraging behavior in a simple manner but that different types of experience induce different behavioral responses.

The evolutionary history of seahorses (Syngnathidae: Hippocampus): molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean.

PubMed

Teske, Peter R; Cherry, Michael I; Matthee, Conrad A

2004-02-01

Sequence data derived from four markers (the nuclear RP1 and Aldolase and the mitochondrial 16S rRNA and cytochrome b genes) were used to determine the phylogenetic relationships among 32 species belonging to the genus Hippocampus. There were marked differences in the rate of evolution among these gene fragments, with Aldolase evolving the slowest and the mtDNA cytochrome b gene the fastest. The RP1 gene recovered the highest number of nodes supported by >70% bootstrap values from parsimony analysis and >95% posterior probabilities from Bayesian inference. The combined analysis based on 2317 nucleotides resulted in the most robust phylogeny. A distinct phylogenetic split was identified between the pygmy seahorse, Hippocampus bargibanti, and a clade including all other species. Three species from the western Pacific Ocean included in our study, namely H. bargibanti, H. breviceps, and H. abdominalis occupy basal positions in the phylogeny. This and the high species richness in the region suggests that the genus evolved somewhere in the West Pacific. There is also fairly strong molecular support for the remaining species being subdivided into three main evolutionary lineages: two West Pacific clades and a clade of species present in both the Indo-Pacific and the Atlantic Ocean. The phylogeny obtained herein suggests at least two independent colonization events of the Atlantic Ocean, once before the closure of the Tethyan seaway, and once afterwards.

Thrips species (Insecta: Thysanoptera) associated with flowers in a restinga fragment in northeastern Brazil.

PubMed

Lima, I M B; Almeida-Filho, M A; Lima, M G A; Bonilla, O H; Lima, E F B

2018-03-22

With the growing volume of research involving Thysanoptera in Brazil, studies were carried out to improve our understanding of the diversity of thrips in areas where the fauna has historically been neglected. Accordingly, we recorded the diversity of thrips (Insecta: Thysanoptera) associated with a restinga fragment located on the campus of the State University of Ceará (UECE), Fortaleza, Ceará state, and computed the estimated richness and diversity indices. Samples were collected from 2011 through 2013 from flowers of 86 plant species. The material was taken to the Laboratory of Insect-Plant Interaction, where thrips were screened under stereomicroscope. We collected 456 adults and 58 immatures, representing 14 species, in addition to one unidentified species of Treherniella. Microcephalothrips abdominalis was found on a large number of host plants, and Frankliniella insularis was the most common species. About two-thirds of the total richness of thrips species was associated with three plant families (Amaranthaceae, Caesalpiniaceae and Poaceae); six thrips species were each associated with only one plant species. The richness of the species collected was close to that estimated by Bootstrap and Jackknife 1 analysis. The Shannon-Wiener (H') and Simpson (D) diversity indexes were 1,7607 and 0.7769, respectively. Although the species are common, 46 new associations between plant species and thrips were established, 13 of which are true host associations, which demonstrates the importance of coastal vegetation in maintaining populations of thrips.

High estradiol and low progesterone are associated with high assertiveness in women.

PubMed

Blake, Khandis R; Bastian, Brock; O'Dean, Siobhan M; Denson, Thomas F

2017-01-01

Sexual selection theory posits that women are more selective than men are when choosing a mate. This evolutionary theory suggests that "choosiness" increases during the fertile window because the costs and benefits of mate selection are highest when women are likely to conceive. Little research has directly investigated reproductive correlates of choice assertion. To address this gap, in the present research we investigated whether fertility, estradiol, and progesterone influenced general assertiveness in women. We recruited 98 naturally cycling, ethnically diverse women. Using a within-subjects design and ovarian hormone concentrations at fertile and non-fertile menstrual cycle phases, we measured implicit assertiveness and self-reported assertive behavior. To see if fertility-induced high assertiveness was related to increased sexual motivation, we also measured women's implicit sexual availability and interest in buying sexy clothes. Results showed that high estradiol and low progesterone predicted higher assertiveness. Sexual availability increased during periods of high fertility. Low progesterone combined with high estradiol predicted greater interest in buying sexy clothes. Results held when controlling for individual differences in mate value and sociosexual orientation. Our findings support the role of fluctuating ovarian hormones in the expression and magnitude of women's assertiveness. High assertiveness during the fertile window may be a psychological adaptation that promotes mate selectivity and safeguards against indiscriminate mate choice when conception risk is highest. Copyright © 2016 Elsevier Ltd. All rights reserved.

Direct benefits of mate choice: a meta-analysis of plumage colour and offspring feeding rates in birds

NASA Astrophysics Data System (ADS)

Hegyi, Gergely; Kötél, Dóra; Laczi, Miklós

2015-10-01

Mate choice is generally costly to the choosy sex, so fitness benefits must counterbalance these costs. Genetic benefits of choice are widely examined and have received overall support. Direct benefits such as high quality parental care by highly ornamented individuals are widely assumed to be important but are less frequently tested, theoretically debated, and their support in the recent literature is unknown. Furthermore, in taxa where both sexes provide care, the preferential investment of the partner in relation to ornamentation may reduce own investment and modify apparent parental care quality. In a phylogenetically controlled meta-analysis, we collated correlative results from birds concerning parental plumage coloration and the nestling feeding rates of the ornament bearer and its partner. Overall evidence was weak for signalling of parental care quality and somewhat stronger for preferential partner investment. Surprisingly, the sex of the signaller and the type of plumage colour seemed to exert weak effects on the signalling of parental care quality. Finally, there was a group of cases with opposite relationships of care and ornamentation in the two parties. We found that this group arose predominately from preferential partner investment in relation to ornamentation, with concomitant, but weaker, reduction of own investment. We conclude that the effect of partner investment on parental care indication seems system-specific and needs further study.

Choosy Wolves? Heterozygote Advantage But No Evidence of MHC-Based Disassortative Mating.

PubMed

Galaverni, Marco; Caniglia, Romolo; Milanesi, Pietro; Lapalombella, Silvana; Fabbri, Elena; Randi, Ettore

2016-03-01

A variety of nonrandom mate choice strategies, including disassortative mating, are used by vertebrate species to avoid inbreeding, maintain heterozygosity and increase fitness. Disassortative mating may be mediated by the major histocompatibility complex (MHC), an important gene cluster controlling immune responses to pathogens. We investigated the patterns of mate choice in 26 wild-living breeding pairs of gray wolf (Canis lupus) that were identified through noninvasive genetic methods and genotyped at 3 MHC class II and 12 autosomal microsatellite (STR) loci. We tested for deviations from random mating and evaluated the covariance of genetic variables at functional and STR markers with fitness proxies deduced from pedigree reconstructions. Results did not show evidences of MHC-based disassortative mating. Rather we found a higher peptide similarity between mates at MHC loci as compared with random expectations. Fitness values were positively correlated with heterozygosity of the breeders at both MHC and STR loci, whereas they decreased with relatedness at STRs. These findings may indicate fitness advantages for breeders that, while avoiding highly related mates, are more similar at the MHC and have high levels of heterozygosity overall. Such a pattern of MHC-assortative mating may reflect local coadaptation of the breeders, while a reduction in genetic diversity may be balanced by heterozygote advantages. © The American Genetic Association 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Pericarpial nectary-visiting ants do not provide fruit protection against pre-dispersal seed predators regardless of ant species composition and resource availability

PubMed Central

Ré Jorge, Leonardo; Benitez-Vieyra, Santiago; Amorim, Felipe W.

2017-01-01

Extrafloral nectaries can occur in both vegetative and reproductive plant structures. In many Rubiaceae species in the Brazilian Cerrado, after corolla abscission, the floral nectary continues to secret nectar throughout fruit development originating post-floral pericarpial nectaries which commonly attract many ant species. The occurrence of such nectar secreting structures might be strategic for fruit protection against seed predators, as plants are expected to invest higher on more valuable and vulnerable parts. Here, we performed ant exclusion experiments to investigate whether the interaction with ants mediated by the pericarpial nectaries of Tocoyena formosa affects plant reproductive success by reducing the number of pre-dispersal seed predators. We also assessed whether ant protection was dependent on ant species composition and resource availability. Although most of the plants were visited by large and aggressive ant species, such as Ectatomma tuberculatum and species of the genus Camponotus, ants did not protect fruits against seed predators. Furthermore, the result of the interaction was neither related to ant species composition nor to the availability of resources. We suggest that these results may be related to the nature and behavior of the most important seed predators, like Hemicolpus abdominalis weevil which the exoskeleton toughness prevent it from being predated by most ant species. On the other hand, not explored factors, such as reward quality, local ant abundance, ant colony characteristics and/or the presence of alternative energetic sources could also account for variations in ant frequency, composition, and finally ant protective effects, highlighting the conditionality of facultative plant-ant mutualisms. PMID:29211790

[Topographico-anatomic data on the testicular artery, ductus deferens artery and cremaster artery in the stallion].

PubMed

Jantosovicová, J; Jantosovic, J

1983-01-01

To study the vascularization of the testis of stallions we used 96 testes. We examined its topography and anatomy by roentgenography, stereoroentgenography, by the corosive method, and by means of gel and China ink injections. To make the roentgeno-arteriograms we used minimum emulsified in glycerine as contrast medium. The branching off of the Aa. testiculares from the Aorta abdominalis is variable in stallions. We observed also a peculiar age-dependent arrangement of the loops of the convolution. In the adult stallion, the shape of the convolution is either cylindrical or conical, spindle-shaped, or irregular. Bifurcation of the A. testicularis before entering the testis did not occur. The epididymical arteries arise either from the convolution or from the Pars recta a. testicularis. They may ramify from a common branch near the origine of A. testicularis. We found regular, direct anastomoses between A. epididymidis cranialis and the branches from the Rr. testiculares. Pars marginalis a. testicularis bifurcates at the transition plane of Margo epididymidis and Margo liber, eventually in the middle 1/3 of Margo epididymidis. Rr. testiculares run parallelly along the Margo liber and give off a number of verically arising branches. The Aa. radiatae centripetales run to the Mediastinum testis without giving off branches. We have not found any anstomoses between the centripetal arteries or the centripetal and centrifugal ones. The A. ductus deferentis is just as thick as the branches from the A. epididymidis caudalis. The lumina of the A. cremasterica is 0.5 to 1 mm. We did not succeed in filling it up reversely through the A. epididymidis caudalis. The artery anastomoses with A. ductus deferentis and A. epididymidis caudalis.

Host plant choice in the comma butterfly-larval choosiness may ameliorate effects of indiscriminate oviposition.

PubMed

Gamberale-Stille, Gabriella; Söderlind, Lina; Janz, Niklas; Nylin, Sören

2014-08-01

In most phytophagous insects, the larval diet strongly affects future fitness and in species that do not feed on plant parts as adults, larval diet is the main source of nitrogen. In many of these insect-host plant systems, the immature larvae are considered to be fully dependent on the choice of the mothers, who, in turn, possess a highly developed host recognition system. This circumstance allows for a potential mother-offspring conflict, resulting in the female maximizing her fecundity at the expense of larval performance on suboptimal hosts. In two experiments, we aimed to investigate this relationship in the polyphagous comma butterfly, Polygonia c-album, by comparing the relative acceptance of low- and medium-ranked hosts between females and neonate larvae both within individuals between life stages, and between mothers and their offspring. The study shows a variation between females in oviposition acceptance of low-ranked hosts, and that the degree of acceptance in the mothers correlates with the probability of acceptance of the same host in the larvae. We also found a negative relationship between stages within individuals as there was a higher acceptance of lower ranked hosts in females who had abandoned said host as a larva. Notably, however, neonate larvae of the comma butterfly did not unconditionally accept to feed from the least favorable host species even when it was the only food source. Our results suggest the possibility that the disadvantages associated with a generalist oviposition strategy can be decreased by larval participation in host plant choice. © 2013 Institute of Zoology, Chinese Academy of Sciences.

[Case-control study on influence factors of birth defects].

PubMed

Xiu, Xin-hong; Yuan, Li; Wang, Xiao-ming; Chen, Yu-hua; Wan, Ai-hua; Fu, Ping

2011-07-01

To investigate the influence factors of birth defects. The congenital malformational fetuses born from 13 week of gestation to 7 days after birth were selected as the study group between April 1st, 2009 and March 31st, 2010. The health born fetuses were set as control in the same period. Case-control and the three-level of monitor network of birth defects were used in the study in the participating 75 hospitals (Qingdao Women and Children's Medical Center, Affiliated Hospital of Medical College Qingdao University, Qingdao Municipal Hospital, etc.). The study and control group's parents were interviewed by an uniformed questionnaire which was designed specially with influence factors of birth defects. (1) There are 466 congenital malformational fetuses in the total of 77 231 fetuses collected in 75 hospitals. The congenital malformational rate accounts for about 6.034‰. The top six defect diseases were congenital heart disease (112 cases), total harelip (cleft lip; cleft lip with palate: 85 cases), polydactyly (53 cases), neural tube defects (38 cases), congenital hydrocephalus (37 cases) and limb reduction defect (27 cases) in turn, which amounts to 353 cases (54.48%, 353/648). (2) Their mother education level in the birth-defect group (25.6%) were significantly lower than that in control group (30.0%, P<0.05). (3) The rate of passive smoking, drinking, raising pets of the parents in birth-defect group were significantly higher than that in control group (P<0.05). (4) The rate of exposure to harmful chemical and physical factors of mothers in birth defects group (13.9% and 20.5%, respectively) was higher than that in control group (1.1% and 11.7%, respectively), the difference between which were significant (P<0.01). The rate of disease (34.3%), fever (13.1%), taking drugs (33.8%) in pregnancy period in birth defect group were higher than that in control group (13.5%, 1.5% and 9.9%, respectively), the difference between which were significant (P<0.01). The rate of bad moral irritation to the mother in pregnancy in birth defect group (11.3%) was significantly higher than that in control group (1.4%, P<0.01). (5) There were 19 cases (2.9%, 19/648) with family heredity medical history in birth defect group, but there were none in the control group, the difference between which were significant (P<0.01). There were 89 cases (13.7%, 89/648) with unusual birth history of their mothers in birth defect group, but there were 31 cases (4.8%, 31/650) in control group, the difference between which were significant (P<0.01). (6) Conditional Logistic Regression model was used for univalent and multivariate analysis. The results showed that main influence factors were identified as having important effect on birth defects, including mothers' exposure to harmful chemical factors (OR=13.46), disease (OR=3.37), taking drugs (OR=2.20), exposure to bad moral irritation (OR=5.44), food-choosy (OR=1.90), anemia (OR=1.52) in gestational period, polyembryony (OR=4.40), father drinking (OR=1.55). While it was protective factors to supplement microelements such as the calcium iron and nutrient, etc.in pregnancy period (OR=0.45). First, the main birth defects were congenital heart disease, total harelip(cleft lip; cleft lip with palate), polydactyly, neural tube defects, congenital hydrocephalus and limb reduction defect in turn. Second, the main influence factors identified as having important effect on birth defects were mothers' exposure to harmful chemical factors, ill, taking drugs, exposure to bad moral irritation, food-choosy, anemia in gestational period, polyembryony, father drinking. But it is protective factors to supplement microelements such as the calcium iron and nutrient, etc. in pregnancy period. Finally, it is the important part to prevent the birth defects by reducing and controlling dangerous factors in pregnancy period.

Butterflies Do Not Alter Conspecific Avoidance in Response to Variation in Density.

PubMed

Jaumann, Sarah; Snell-Rood, Emilie C

2017-08-01

High conspecific densities are associated with increased levels of intraspecific competition and a variety of negative effects on performance. However, changes in life history strategy could compensate for some of these effects. For instance, females in crowded conditions often have fewer total offspring, but they may invest more in each one. Such investment could include the production of larger offspring, more time spent engaging in parental care, or more choosy decisions about where offspring are placed. For animals that have a relatively immobile juvenile stage, the costs of competition can be particularly high. Females may be able to avoid such costs by investing more in individual reproductive decisions, rearing young or laying eggs in locations away from other females. We tested the hypothesis that conspecific density cues during juvenile and adult life stages lead to changes in life history strategy, including both reproduction and oviposition choices. We predicted that high-density cues during the larval and adult stages of female Pieris rapae butterflies lead to lower fecundity but higher conspecific avoidance during oviposition, compared to similar low-density cues. We used a 2×2 factorial design to examine the effects of low and high conspecific density during the larval and adult stages of butterflies on avoidance behavior and fecundity. We found that past information about conspecific density did not matter; all butterflies exhibited similar levels of fecundity and a low level of conspecific avoidance during oviposition regardless of their previous experience as larvae and adults. These results suggest that P. rapae females use a fixed, rather than flexible, conspecific avoidance strategy when making oviposition decisions, and past information about conspecific density has no effect on life history and current reproductive investment. We speculate that this may be partially because past conspecific density per se is not a reliable cue for predicting current density and levels of competition, and thus it does not affect the development of life history strategies in this system. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Male-Male Clasping May Be Part of an Alternative Reproductive Tactic in Xenopus laevis

PubMed Central

Rhodes, Heather J.; Stevenson, Rachel J.; Ego, Courtney L.

2014-01-01

Male Xenopus laevis frogs have been observed to clasp other males in a sustained, amplectant position, the purpose of which is unknown. We examined three possible hypotheses for this counter-intuitive behavior: 1) clasping males fail to discriminate the sex of the frogs they clasp; 2) male-male clasping is an aggressive or dominant behavior; or 3) that males clasp other males to gain proximity to breeding events and possibly engage in sperm competition. Our data, gathered through a series of behavioral experiments in the laboratory, refute the first two hypotheses. We found that males did not clasp indiscriminately, but showed a sex preference, with most males preferentially clasping a female, but a proportion preferentially clasping another male. Males that clasped another male when there was no female present were less likely to “win” reproductive access in a male-male-female triad, indicating that they did not establish dominance through clasping. However, those males did gain proximity to oviposition by continued male-male clasping in the presence of the female. Thus, our findings are consistent with, but cannot confirm, the third hypothesis of male-male clasping as an alternative reproductive tactic. PMID:24849114

Do females pay attention to secondary sexual coloration in vervet monkeys ( Chlorocebus aethiops)?

NASA Astrophysics Data System (ADS)

Gerald, Melissa S.; Ayala, James; Ruíz-Lambides, Angelina; Waitt, Corri; Weiss, Alexander

2010-01-01

Several primate species show sexual dichromatism with males displaying conspicuous coloration of the pelage or skin. Studies of scrotal coloration in male vervet monkeys ( Chlorocebus aethiops) suggest that it is an important intrasexual signal, with relatively dark, colourful males dominating paler males. To date, no studies have examined the influence of male colour on intersexual social interactions in vervet monkeys. The primary goal of the present study was to evaluate whether female vervet monkeys attend to male coloration. We experimentally introduced females, housed with either “pale” or “dark” males, to stimulus males whose scrota were pale, dark, or pale but painted to look dark. Overall, during introductions, females did not differ in time spent directing affiliative behaviour toward pale, dark, and painted males; however, females, permanently housed with dark males, spent significantly more time directing affiliative behaviour toward pale than painted males. When the stimulus male was pale, affiliative exchanges between males and females were longer than when the stimulus male was painted. Home male colour was not related to female-initiated aggression. Home male colour was also not related to male-initiated aggression, although painted stimulus males were more likely to initiate aggression than pale stimulus males. These findings lead us to conclude that females pay attention to male coloration, but do not bias their interactions toward males solely on the basis of natural male coloration.

Do females pay attention to secondary sexual coloration in vervet monkeys (Chlorocebus aethiops)?

PubMed

Gerald, Melissa S; Ayala, James; Ruíz-Lambides, Angelina; Waitt, Corri; Weiss, Alexander

2010-01-01

Several primate species show sexual dichromatism with males displaying conspicuous coloration of the pelage or skin. Studies of scrotal coloration in male vervet monkeys (Chlorocebus aethiops) suggest that it is an important intrasexual signal, with relatively dark, colourful males dominating paler males. To date, no studies have examined the influence of male colour on intersexual social interactions in vervet monkeys. The primary goal of the present study was to evaluate whether female vervet monkeys attend to male coloration. We experimentally introduced females, housed with either "pale" or "dark" males, to stimulus males whose scrota were pale, dark, or pale but painted to look dark. Overall, during introductions, females did not differ in time spent directing affiliative behaviour toward pale, dark, and painted males; however, females, permanently housed with dark males, spent significantly more time directing affiliative behaviour toward pale than painted males. When the stimulus male was pale, affiliative exchanges between males and females were longer than when the stimulus male was painted. Home male colour was not related to female-initiated aggression. Home male colour was also not related to male-initiated aggression, although painted stimulus males were more likely to initiate aggression than pale stimulus males. These findings lead us to conclude that females pay attention to male coloration, but do not bias their interactions toward males solely on the basis of natural male coloration.

Influence of male morphology on male mating status and behavior during interunit encounters in western lowland gorillas.

PubMed

Caillaud, Damien; Levréro, Florence; Gatti, Sylvain; Ménard, Nelly; Raymond, Michel

2008-04-01

The western lowland gorilla (Gorilla gorilla gorilla) is one of the most sexually dimorphic primate species. Mature males are twice the size of females and have grey fur on their backs and a fibrous, adipose crest on their heads. Such traits are likely to have evolved by sexual selection, either because they confer advantages during male-male fights or because females prefer males with more dimorphic traits. We developed photogrammetric methods for distance collection of morphological data from silverback males frequenting the Lokoué forest clearing in Odzala-Kokoua National Park, Republic of the Congo. Body length, head-crest size, musculature development, and extent of the grey color on the back were assessed in 87 nonbreeding and breeding mature males. Behavioral data were also collected during 312 male-male encounters involving 67 mature males in order to estimate their level of aggressiveness. The number of females belonging to a mature male positively correlated with the male crest size, body length, and musculature. Whereas morphological variables did not significantly affect the intensity of male-male encounters, the number of females attending male-male encounters strongly affected the number of agonistic displays by the two males. We discuss the mechanisms through which males with more exaggerated traits could obtain a mating advantage, namely male-male fights or female mate choice. (c) 2007 Wiley-Liss, Inc.

Vocal communication between male Xenopus laevis.

PubMed

Tobias, Martha L; Barnard, Candace; O'Hagan, Robert; Horng, Sam H; Rand, Masha; Kelley, Darcy B

2004-02-01

This study focuses on the role of male-male vocal communication in the reproductive repertoire of the South African clawed frog, Xenopus laevis . Six male and two female call types were recorded from native ponds in the environs of Cape Town, South Africa. These include all call types previously recorded in the laboratory as well as one previously unidentified male call: chirping. The amount of calling and the number of call types increased as the breeding season progressed. Laboratory recordings indicated that all six male call types were directed to males; three of these were directed to both sexes and three were directed exclusively to males. Both female call types were directed exclusively to males. The predominant call type, in both field and laboratory recordings, was the male advertisement call. Sexual state affected male vocal behaviour. Male pairs in which at least one male was sexually active (gonadotropin injected) produced all call types, whereas pairs of uninjected males rarely called. Some call types were strongly associated with a specific behaviour and others were not. Clasped males always growled and clasping males typically produced amplectant calls or chirps; males not engaged in clasping most frequently advertised. The amount of advertising produced by one male was profoundly affected by the presence of another male. Pairing two sexually active males resulted in suppression of advertisement calling in one; suppression was released when males were isolated after pairing. Vocal dominance was achieved even in the absence of physical contact (clasping). We suggest that X. laevis males gain a reproductive advantage by competing for advertisement privileges and by vocally suppressing neighbouring males.

Alpha male replacements and delayed dispersal in crested macaques (Macaca nigra).

PubMed

Marty, Pascal R; Hodges, Keith; Agil, Muhammad; Engelhardt, Antje

2017-07-01

In species with a high male reproductive skew, competition between males for the top dominant position is high and escalated fights are common between competitors. As a consequence, challenges incur potentially high costs. Selection should favor males who time an alpha male challenge to maximize chances of a successful outcome minimizing costs. Despite the importance of alpha male replacements for individual males, we know little about the timing of challenges and the condition of the challenger. We investigated the timing and process of alpha male replacements in a species living in multi-male groups with high male reproductive skew, the crested macaque. We studied four wild groups over 6 years in the Tangkoko Reserve, North Sulawesi, Indonesia, during which 16 alpha male replacements occurred. Although unusual for cercopithecines, male crested macaques delayed their natal dispersal until they attained maximum body mass and therefore fighting ability whereupon they emigrated and challenged the alpha male in another group. Accordingly, all observed alpha male replacements were from outside males. Ours is the first report of such a pattern in a primate species living in multi-male groups. Although the majority of alpha male replacements occurred through direct male-male challenges, many also took place opportunistically (i.e., after the alpha male had already been injured or had left the group). Furthermore, alpha male tenures were very short (averaging ca. 12 months). We hypothesize that this unusual pattern of alpha male replacements in crested macaques is related to the species-specific combination of high male reproductive skew with a large number of males per group. Am. J. Primatol. 79:e22448, 2017. © 2015 The Authors. American Journal of Primatology Published by Wiley Periodicals, Inc. © 2015 The Authors. American Journal of Primatology Published by Wiley Periodicals, Inc.

Does large body size in males evolve to facilitate forcible insemination? A study on garter snakes.

PubMed

Shine, Richard; Mason, Robert T

2005-11-01

A trend for larger males to obtain a disproportionately high number of matings, as occurs in many animal populations, typically is attributed either to female choice or success in male-male rivalry; an alternative mechanism, that larger males are better able to coercively inseminate females, has received much less attention. For example, previous studies on garter snakes (Thamnophis sirtalis parietalis) at communal dens in Manitoba have shown that the mating benefit to larger body size in males is due to size-dependent advantages in male-male rivalry. However, this previous work ignored the possibility that larger males may obtain more matings because of male-female interactions. In staged trials within outdoor arenas, larger body size enhanced male mating success regardless of whether a rival male was present. The mechanism involved was coercion rather than female choice, because mating occurred most often (and soonest) in females that were least able to resist courtship-induced hypoxic stress. Males do physically displace rivals from optimal positions in the mating ball, and larger males are better able to resist such displacement. Nonetheless, larger body size enhances male mating success even in the absence of such male-male interactions. Thus, even in mating systems where males compete physically and where larger body size confers a significant advantage in male-male competition, the actual selective force for larger body size in males may relate to forcible insemination of unreceptive females. Experimental studies are needed to determine whether the same situation occurs in other organisms in which body-size advantages have been attributed to male-male rather than male-female interactions.

Will male advertisement be a reliable indicator of paternal care, if offspring survival depends on male care?

PubMed Central

Kelly, Natasha B.; Alonzo, Suzanne H.

2009-01-01

Existing theory predicts that male signalling can be an unreliable indicator of paternal care, but assumes that males with high levels of mating success can have high current reproductive success, without providing any parental care. As a result, this theory does not hold for the many species where offspring survival depends on male parental care. We modelled male allocation of resources between advertisement and care for species with male care where males vary in quality, and the effect of care and advertisement on male fitness is multiplicative rather than additive. Our model predicts that males will allocate proportionally more of their resources to whichever trait (advertisement or paternal care) is more fitness limiting. In contrast to previous theory, we find that male advertisement is always a reliable indicator of paternal care and male phenotypic quality (e.g. males with higher levels of advertisement never allocate less to care than males with lower levels of advertisement). Our model shows that the predicted pattern of male allocation and the reliability of male signalling depend very strongly on whether paternal care is assumed to be necessary for offspring survival and how male care affects offspring survival and male fitness. PMID:19520802

Sexual conflict over mating in Gnatocerus cornutus? Females prefer lovers not fighters.

PubMed

Okada, Kensuke; Katsuki, Masako; Sharma, Manmohan D; House, Clarissa M; Hosken, David J

2014-06-22

Female mate choice and male-male competition are the typical mechanisms of sexual selection. However, these two mechanisms do not always favour the same males. Furthermore, it has recently become clear that female choice can sometimes benefit males that reduce female fitness. So whether male-male competition and female choice favour the same or different males, and whether or not females benefit from mate choice, remain open questions. In the horned beetle, Gnatocerus cornutus, males have enlarged mandibles used to fight rivals, and larger mandibles provide a mating advantage when there is direct male-male competition for mates. However, it is not clear whether females prefer these highly competitive males. Here, we show that female choice targets male courtship rather than mandible size, and these two characters are not phenotypically or genetically correlated. Mating with attractive, highly courting males provided indirect benefits to females but only via the heritability of male attractiveness. However, mating with attractive males avoids the indirect costs to daughters that are generated by mating with competitive males. Our results suggest that male-male competition may constrain female mate choice, possibly reducing female fitness and generating sexual conflict over mating.

Will male advertisement be a reliable indicator of paternal care, if offspring survival depends on male care?

PubMed

Kelly, Natasha B; Alonzo, Suzanne H

2009-09-07

Existing theory predicts that male signalling can be an unreliable indicator of paternal care, but assumes that males with high levels of mating success can have high current reproductive success, without providing any parental care. As a result, this theory does not hold for the many species where offspring survival depends on male parental care. We modelled male allocation of resources between advertisement and care for species with male care where males vary in quality, and the effect of care and advertisement on male fitness is multiplicative rather than additive. Our model predicts that males will allocate proportionally more of their resources to whichever trait (advertisement or paternal care) is more fitness limiting. In contrast to previous theory, we find that male advertisement is always a reliable indicator of paternal care and male phenotypic quality (e.g. males with higher levels of advertisement never allocate less to care than males with lower levels of advertisement). Our model shows that the predicted pattern of male allocation and the reliability of male signalling depend very strongly on whether paternal care is assumed to be necessary for offspring survival and how male care affects offspring survival and male fitness.

Male-mimicking females increase male-male interactions, and decrease male survival and condition in a female-polymorphic damselfly.

PubMed

Gering, Eben J

2017-05-01

Biologists are still discovering diverse and powerful ways sexual conflicts shape biodiversity. The present study examines how the proportion of females in a population that exhibit male mimicry, a mating resistance trait, influences conspecific males' behavior, condition, and survival. Like most female-polymorphic damselflies, Ischnura ramburii harbors both "andromorph" females, which closely resemble males, and sexually dimorphic "gynomorph" counterparts. There is evidence that male mimicry helps andromorphs evade detection and harassment, but males can also learn to target locally prevalent morph(s) via prior mate encounters. I hypothesized that the presence of male mimics could therefore predispose males to mate recognition errors, and thereby increase rates of costly male-male interactions. Consistent with this hypothesis, male-male interaction rates were highest in mesocosms containing more andromorph (vs. gynomorph) females. Males in andromorph-biased mesocosms also had lower final body mass and higher mortality than males assigned to gynomorph-majority treatments. Male survival and body mass were each negatively affected by mesocosm density, and mortality data revealed a marginally significant interaction between andromorph frequency and population density. These findings suggest that, under sufficiently crowded conditions, female mating resistance traits such as male mimicry could have pronounced indirect effects on male behavior, condition, and survival. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Patterns of interventions and the effect of coalitions and sociality on male fitness

PubMed Central

Kulik, Lars; Muniz, Laura; Mundry, Roger; Widdig, Anja

2011-01-01

In group living animals, especially among primates, there is consistent evidence that high-ranking males gain a higher reproductive output than low-ranking males. Primate studies have shown that male coalitions and sociality can impact male fitness; however, it remains unclear whether males could potentially increase their fitness by preferentially supporting and socializing with females. Here we investigate patterns of male interventions and the effect of coalitions and sociality on male fitness in rhesus macaques (Macaca mulatta) with particular focus on male-female interactions. We combined behavioral collected on Cayo Santiago with genetic data analyzed for male reproductive output and relatedness. Our results revealed that the ten top-ranking males provided the majority of all male support observed. In contrast to other primates, male rhesus macaques mainly formed all-down coalitions suggesting that coalitions are less likely used to enhance male dominance. Males supporting females during and before their likely conception were not more likely to fertilize those females. We also found no evidence that males preferably support their offspring or other close kin. Interestingly, the most important predictor of male support was sociality, since opponents sharing a higher sociality index with a given male were more likely to be supported. Furthermore, a high sociality index of a given male-female dyad resulted in a higher probability of paternity. Overall, our results strengthen the evidence that sociality affects fitness in male primates, but also suggest that in species in which males queue for dominance, it is less likely that males derive fitness benefits from coalitions. PMID:21880090

Patterns of interventions and the effect of coalitions and sociality on male fitness.

PubMed

Kulik, Lars; Muniz, Laura; Mundry, Roger; Widdig, Anja

2012-02-01

In group living animals, especially among primates, there is consistent evidence that high-ranking males gain a higher reproductive output than low-ranking males. Primate studies have shown that male coalitions and sociality can impact male fitness; however, it remains unclear whether males could potentially increase their fitness by preferentially supporting and socializing with females. Here we investigate patterns of male interventions and the effect of coalitions and sociality on male fitness in rhesus macaques (Macaca mulatta) with particular focus on male-female interactions. We combined behavioural observations collected on Cayo Santiago with genetic data analysed for male reproductive output and relatedness. Our results revealed that the ten top-ranking males provided the majority of all male support observed. In contrast to other primates, male rhesus macaques mainly formed all-down coalitions suggesting that coalitions are less likely used to enhance male dominance. Males supporting females during and before their likely conception were not more likely to fertilize those females. We also found no evidence that males preferably support their offspring or other close kin. Interestingly, the most important predictor of male support was sociality, since opponents sharing a higher sociality index with a given male were more likely to be supported. Furthermore, a high sociality index of a given male-female dyad resulted in a higher probability of paternity. Overall, our results strengthen the evidence that sociality affects fitness in male primates, but also suggest that in species in which males queue for dominance, it is less likely that males derive fitness benefits from coalitions. © 2011 Blackwell Publishing Ltd.

Interactions among mechanisms of sexual selection on male body size and head shape in a sexually dimorphic fly.

PubMed

Bonduriansky, Russell; Rowe, Locke

2003-09-01

Darwin envisaged male-male and male-female interactions as mutually supporting mechanisms of sexual selection, in which the best armed males were also the most attractive to females. Although this belief continues to predominate today, it has been challenged by sexual conflict theory, which suggests that divergence in the interests of males and females may result in conflicting sexual selection. This raises the empirical question of how multiple mechanisms of sexual selection interact to shape targeted traits. We investigated sexual selection on male morphology in the sexually dimorphic fly Prochyliza xanthostoma, using indices of male performance in male-male and male-female interactions in laboratory arenas to calculate gradients of direct, linear selection on male body size and an index of head elongation. In male-male combat, the first interaction with a new opponent selected for large body size but reduced head elongation, whereas multiple interactions with the same opponent favored large body size only. In male-female interactions, females preferred males with relatively elongated heads, but male performance of the precopulatory leap favored large body size and, possibly, reduced head elongation. In addition, the amount of sperm transferred (much of which is ingested by females) was an increasing function of both body size and head elongation. Thus, whereas both male-male and male-female interactions favored large male body size, male head shape appeared to be subject to conflicting sexual selection. We argue that conflicting sexual selection may be a common result of divergence in the interests of the sexes.

Life history in male mandrills (Mandrillus sphinx): physical development, dominance rank, and group association.

PubMed

Setchell, Joanna M; Wickings, E Jean; Knapp, Leslie A

2006-12-01

We assess life history from birth to death in male mandrills (Mandrillus sphinx) living in a semifree-ranging colony in Gabon, using data collected for 82 males that attained at least the age of puberty, including 33 that reached adulthood and 25 that died, yielding data for their entire lifespan. We describe patterns of mortality and injuries, dominance rank, group association, growth and stature, and secondary sexual character expression across the male lifespan. We examine relationships among these variables and investigate potential influences on male life history, including differences in the social environment (maternal rank and group demography) and early development, with the aim of identifying characteristics of successful males. Sons of higher-ranking females were more likely to survive to adulthood than sons of low-ranking females. Adolescent males varied consistently in the rate at which they developed, and this variation was related to a male's own dominance rank. Males with fewer peers and sons of higher-ranking and heavier mothers also matured faster. However, maternal variables were not significantly related to dominance rank during adolescence, the age at which males attained adult dominance rank, or whether a male became alpha male. Among adult males, behavior and morphological development were related to a male's own dominance rank, and sons of high-ranking females were larger than sons of low-ranking females. Alpha males were always the most social, and the most brightly colored males, but were not necessarily the largest males present. Finally, alpha male tenure was related to group demography, with larger numbers of rival adult males and maturing adolescent males reducing the time a male spent as alpha male. Tenure did not appear to be related to characteristics of the alpha male himself. 2006 Wiley-Liss, Inc.

Alpha male replacements and delayed dispersal in crested macaques (Macaca nigra)

PubMed Central

Hodges, Keith; Agil, Muhammad; Engelhardt, Antje

2015-01-01

In species with a high male reproductive skew, competition between males for the top dominant position is high and escalated fights are common between competitors. As a consequence, challenges incur potentially high costs. Selection should favor males who time an alpha male challenge to maximize chances of a successful outcome minimizing costs. Despite the importance of alpha male replacements for individual males, we know little about the timing of challenges and the condition of the challenger. We investigated the timing and process of alpha male replacements in a species living in multi‐male groups with high male reproductive skew, the crested macaque. We studied four wild groups over 6 years in the Tangkoko Reserve, North Sulawesi, Indonesia, during which 16 alpha male replacements occurred. Although unusual for cercopithecines, male crested macaques delayed their natal dispersal until they attained maximum body mass and therefore fighting ability whereupon they emigrated and challenged the alpha male in another group. Accordingly, all observed alpha male replacements were from outside males. Ours is the first report of such a pattern in a primate species living in multi‐male groups. Although the majority of alpha male replacements occurred through direct male‐male challenges, many also took place opportunistically (i.e., after the alpha male had already been injured or had left the group). Furthermore, alpha male tenures were very short (averaging ca. 12 months). We hypothesize that this unusual pattern of alpha male replacements in crested macaques is related to the species‐specific combination of high male reproductive skew with a large number of males per group. Am. J. Primatol. 79:e22448, 2017. © 2015 The Authors. American Journal of Primatology Published by Wiley Periodicals, Inc. PMID:26194621

Evidence for volatile male-produced pheromone in banana weevilCosmopolites sordidus.

PubMed

Budenberg, W J; Ndiege, I O; Karago, F W

1993-09-01

Females of the banana weevil,Cosmopolites sordidus, were attracted to and made longer visits to live conspecific males, trapped volatiles from males, and dissected male hindguts in a still-air olfactometer. Male weevils were attracted to volatiles trapped from males and made longer visits to live males and volatiles from males. Live females, collected volatiles from females and female hindguts, elicited small or no behavioral responses from either sex. Electroantennogram (EAG) responses from both male and female antennae were elicited by collected volatiles from males and by dichloromethane extracts of male hindguts and bodies but not by surface washes of males. No significant EAG responses were given to equivalent material from females. It is therefore suggested that male banana weevils release an aggregation pheromone via their hindgut.

Sexually selected nest-building--Pomatoschistus minutus males build smaller nest-openings in the presence of sneaker males.

PubMed

Svensson, O; Kvarnemo, C

2003-09-01

Both natural selection and sexual selection may act on nest-building. We tested experimentally how different regimes of egg-predation and male-male competition influence nest-building before mating, using the marine fish sand goby, Pomatoschistus minutus. Males with sneaker males present built the smallest nest-openings, smaller than males held alone or with Pomatoschistus microps males (which may predate eggs and compete over nest-sites but not compete over fertilizations). Males with visual access to other nest-building males tended also to build smaller openings than males held alone or with P. microps. Males with egg-predators present built nests with openings not differing significantly from any other treatment. Our results indicate that the small nest-openings found in the sneaker male treatment are sexually selected through protection against sneaking or by female choice. Across treatments, time span before a male started to build his nest also explained variation in nest-opening width; males starting late built larger nest-openings.

Assortative sexual mixing patterns in male-female and male-male partnerships in Melbourne, Australia: implications for HIV and sexually transmissible infection transmission.

PubMed

Chow, Eric P F; Read, Tim R H; Law, Matthew G; Chen, Marcus Y; Bradshaw, Catriona S; Fairley, Christopher K

2016-10-01

Assortative mixing patterns have become a new and important focus in HIV/sexually transmissible infection (STI) research in recent years. There are very limited data on sexual mixing patterns, particularly in an Australian population. Male-female and male-male partnerships attending the Melbourne Sexual Health Centre (MSHC) between 2011 and 2014 were included. Correlation of age between two individuals within a partnership was examined by using Spearman's rank correlation. The Newman's assortativity coefficient was used as an aggregate quantitative measurement of sexual mixing for number of partners and condom use. 1165 male-female and 610 male-male partnerships were included in the analysis. There was a strong positive correlation of age in both male-female (rho=0.709; P<0.001) and male-male partnerships (rho=0.553; P<0.001). The assortative mixing pattern for number of partners was similar in male-female (r=0.255; 95% CI: 0.221-0.289) and male-male partnerships (r=0.264; 95% CI: 0.218-0.309). There was a stronger assortative mixing pattern for condom use in male-male (r=0.517, 95% CI: 0.465-0.569) compared with male-female (r=0.382; 95% CI: 0.353-0.412) partnerships. Male-female and male-male partnerships have a high assortativity mixing pattern for age, number of partners and condom use. The sexual mixing pattern is not purely assortative, and hence it may lead to increased HIV and STI transmission in certain risk groups.

Flat lizard female mimics use sexual deception in visual but not chemical signals

PubMed Central

Whiting, Martin J.; Webb, Jonathan K.; Keogh, J. Scott

2009-01-01

Understanding what constrains signalling and maintains signal honesty is a central theme in animal communication. Clear cases of dishonest signalling, and the conditions under which they are used, represent an important avenue for improved understanding of animal communication systems. Female mimicry, when certain males take on the appearance of females, is most commonly a male alternative reproductive tactic that is condition-dependent. A number of adaptive explanations for female mimicry have been proposed including avoiding the costs of aggression, gaining an advantage in combat, sneaking copulations with females on the territories of other males, gaining physiological benefits and minimizing the risk of predation. Previous studies of female mimicry have focused on a single mode of communication, although most animals communicate using multiple signals. Male Augrabies flat lizards adopt alternative reproductive tactics in which some males (she-males) mimic the visual appearance of females. We experimentally tested in a wild population whether she-males are able to mimic females using both visual and chemical signals. We tested chemical recognition in the field by removing scent and relabelling females and she-males with either male or female scent. At a distance, typical males (he-males) could not distinguish she-males from females using visual signals, but during close encounters, he-males correctly determined the gender of she-males using chemical signals. She-males are therefore able to deceive he-males using visual but not chemical signals. To effectively deceive he-males, she-males avoid close contact with he-males during which chemical cues would reveal their deceit. This strategy is probably adaptive, because he-males are aggressive and territorial; by mimicking females, she-males are able to move about freely and gain access to females on the territories of resident males. PMID:19324828

Effects of sodium puddling on male mating success, courtship and flight in a swallowtail butterfly

PubMed Central

Mitra, Chandreyee; Reynoso, Edgar; Davidowitz, Goggy; Papaj, Daniel

2016-01-01

In many Lepidoptera species usually only males puddle for sodium. Two explanations have been offered for this: (1) neuromuscular activity: males need increased sodium for flight because they are more active flyers than females; and (2) direct benefits: sodium is a type of direct benefit provided by males to females via ejaculate during mating. Surprisingly, there is little direct experimental evidence for either of these. In this study, we examined both explanations using the pipevine swallowtail butterfly, Battus philenor L. If sodium increases neuromuscular activity, males consuming sodium should be better fliers than males without sodium. If males collect sodium for nuptial gifts that benefit their mates, males consuming sodium may have greater mating success than males without sodium. In that case, females then need an honest cue/signal of the quality of male-provided direct benefits that they can assess before mating. If sodium affects male courtship flight by increasing neuromuscular activity, how a male courts could serve as such a premating cue/signal of male benefit quality. Therefore, sodium may benefit males in terms of obtaining mates by increasing their neuromuscular activity. In this study we found that males that consumed sodium courted more vigorously and had greater mating success than males that consumed water. In addition, the courtship displays of males consuming sodium were significantly different from those of males consuming water, providing a possible honest cue/signal of male benefit quality that females can assess. Interestingly, we did not find evidence that sodium consumption affects male flight outside of courtship. That only aspects of male flight related to mating were affected by sodium, while aspects of general flight were not, is consistent with the idea that sodium may benefit males in terms of obtaining mates via effects on neuromuscular activity. PMID:27103748

Ejaculate of sneaker males is pheromonally inconspicuous in the black goby, Gobius niger (Teleostei, Gobiidae).

PubMed

Locatello, L; Mazzoldi, C; Rasotto, M B

2002-11-01

The black goby, Gobius niger, shows alternative male mating tactics, i.e., parental and sneaker males. Males release a sexual pheromone that attracts females and stimulates aggressive displays in males. This pheromone is produced by the mesorchial gland, a structure well developed in parental males but markedly undeveloped in sneakers. We measured the behavioral response of parental males to the ejaculates of males performing different reproductive tactics. Parental males reacted to the ejaculate of other parental males, with stereotypic aggressive behaviors, but not to the ejaculate of sneakers; consequently sneaker male ejaculate appears to be pheromonally inconspicuous. Copyright 2002 Wiley-Liss, Inc.

Male fighting and "territoriality" within colonies of the ant Cardiocondyla venustula.

PubMed

Frohschammer, Sabine; Heinze, Jürgen

2009-01-01

The ant genus Cardiocondyla is characterized by a bizarre male polymorphism with wingless fighter males and winged disperser males. Winged males have been lost convergently in several clades, and in at least one of them, wingless males have evolved mutual tolerance. To better understand the evolutionary pathways of reproductive tactics, we investigated Cardiocondyla venustula, a species, which in a phylogenetic analysis clusters with species with fighting and species with mutually tolerant, wingless males. Wingless males of C. venustula use their strong mandibles to kill freshly eclosed rival males and also engage in short fights with other adult males, but in addition show a novel behavior hitherto not reported from social insect males: they spread out in the natal nest and defend "territories" against other males. Ant males therefore show a much larger variety of reproductive tactics than previously assumed.

Male fighting and ``territoriality'' within colonies of the ant Cardiocondyla venustula

NASA Astrophysics Data System (ADS)

Frohschammer, Sabine; Heinze, Jürgen

2009-01-01

The ant genus Cardiocondyla is characterized by a bizarre male polymorphism with wingless fighter males and winged disperser males. Winged males have been lost convergently in several clades, and in at least one of them, wingless males have evolved mutual tolerance. To better understand the evolutionary pathways of reproductive tactics, we investigated Cardiocondyla venustula, a species, which in a phylogenetic analysis clusters with species with fighting and species with mutually tolerant, wingless males. Wingless males of C. venustula use their strong mandibles to kill freshly eclosed rival males and also engage in short fights with other adult males, but in addition show a novel behavior hitherto not reported from social insect males: they spread out in the natal nest and defend “territories” against other males. Ant males therefore show a much larger variety of reproductive tactics than previously assumed.

Factors affecting aggressive behaviour of spawning migratory males towards mature male parr in masu salmon Oncorhynchus masou.

PubMed

Watanabe, M; Maekawa, K

2010-07-01

This study examined whether dominant migratory males (adopting fighter tactics) of the masu salmon Oncorhynchus masou would more aggressively attack large mature male parr (adopting sneaker tactics) as large mature male parr are expected to have the potential to cause a greater decrease in fertilization success. The frequency of aggressive behaviour was not related to the body size of males, and it increased with the frequency of interactions with mature male parr. The fertilization success of mature male parr was much lower than migratory males, and no relationship was observed between fertilization success and aggressive behaviour. The low fertilization success of mature male parr, despite infrequent aggressive behaviour by migratory males, indicates that there might be little benefit for migratory males to attack mature male parr more aggressively according to their body size.

Alternative phenotypes of male mating behaviour in the two-spotted spider mite.

PubMed

Sato, Yukie; Sabelis, Maurice W; Egas, Martijn; Faraji, Farid

2013-09-01

Severe intraspecific competition for mates selects for aggressive individuals but may also lead to the evolution of alternative phenotypes that do not act aggressively, yet manage to acquire matings. The two-spotted spider mite, Tetranychus urticae, shows male mate-guarding behaviour and male-male combat for available females. This may provide opportunity for weaker males to avoid fighting by adopting alternative mating behaviour such as sneaker or satellite tactics as observed in other animals. We investigated male precopulatory behaviour in the two-spotted spider mite by means of video-techniques and found three types of male mating behaviour: territorial, sneaker and opportunistic. Territorial and sneaker males associate with female teleiochrysales and spend much time guarding them. Territorial males are easily disturbed by rival males and engage themselves in fights with them. However, sneaker males are not at all disturbed by rival males, never engage in fights and, strikingly, never face attack by territorial males. Opportunistic males wander around in search of females that are in the teleiochrysalis stage but very close to or at emergence. To quickly classify any given mate-guarding male as territorial or sneaker we developed a method based on the instantaneous response of males to disturbance by a live male mounted on top of a brush. We tested this method against the response of the same males to natural disturbance by two or three other males. Because this method proved to be successful, we used it to collect territorial and sneaker males, and subjected them to morphological analysis to assess whether the various behavioural phenotypes are associated with different morphological characters. However, we found no statistical differences between territorial and sneaker males, concerning the length of the first legs, the stylets, the pedipalps or the body.

Cuticular lipids and odors induce sex-specific behaviors in the male cricket Gryllus bimaculatus.

PubMed

Iwasaki, Masazumi; Katagiri, Chihiro

2008-03-01

Male crickets display sex-specific (e.g., mating and agonistic) behaviors towards conspecific individuals. One of the key signals for these behaviors is the chemical substance on the cricket body surface. In the present study, we analyzed female and male cuticular substances in behavioral assays. Antennal contact stimulation using female forewings elicited a mating behavior in males, while that using male forewings elicited an agonistic behavior in males. Thin-layer-chromatographic and other techniques analysis showed that saturated cuticular lipids were present in both female and male cuticles and that unsaturated lipids were present only in the male cuticle. Filter papers soaked with saturated or unsaturated cuticular lipids were applied to antennae of male crickets. Males showed mating behavior in response to stimulation with saturated lipids from both females and males but showed avoidance behavior in response to stimulation with male unsaturated lipids. Because cuticular lipids did not induce agonistic behavior in males, we collected odors from male crickets and found that these odors induced agonistic behavior in males. Therefore, we concluded that the key signals for mating, avoidance and agonistic behaviors of male crickets are comprised of at least three different components, saturated and unsaturated cuticular lipids and male odors, respectively.

Mutation of Drosophila dopamine receptor DopR leads to male-male courtship behavior.

PubMed

Chen, Bin; Liu, He; Ren, Jing; Guo, Aike

2012-07-06

In Drosophila, dopamine plays important roles in many biological processes as a neuromodulator. Previous studies showed that dopamine level could affect fly courtship behaviors. Disturbed dopamine level leads to abnormal courtship behavior in two different ways. Dopamine up-regulation induces male-male courtship behavior, while down-regulation of dopamine level results in increased sexual attractiveness of males towards other male flies. Until now, the identity of the dopamine receptor involved in this abnormal male-male courtship behavior remains unknown. Here we used genetic approaches to investigate the role of dopamine receptors in fly courtship behavior. We found that a dopamine D1-like receptor, DopR, was involved in fly courtship behavior. DopR mutant male flies display male-male courtship behavior. This behavior is mainly due to the male's increased propensity to court other males. Expression of functional DopR successfully rescued this mutant phenotype. Knock-down of D2-like receptor D2R and another D1-like receptor, DAMB, did not induce male-male courtship behavior, indicating the receptor-type specificity of this phenomenon. Our findings provide insight into a possible link between dopamine level disturbance and the induced male-male courtship behavior. Copyright © 2012 Elsevier Inc. All rights reserved.

The association between male-biased sex ratio and indicators of stress in red-spotted newts.

PubMed

Aspbury, Andrea S; Grayson, Kristine L; Fantaye, Selamawit; Nichols, Ian; Myers-Burton, Miranda; Ortiz-Mangual, Xavier; Gabor, Caitlin R

2017-05-01

In populations with a male-biased operational sex ratio, coercive mating by males can have fitness consequences for females. One component of reduced fitness for females in populations with a male-biased OSR may be greater activation of the stress response, resulting in higher corticosterone release rates (CORT; a glucocorticoid stress hormone in amphibians). We test the hypothesis that a male-biased sex ratio affects female activity and release rates of CORT and testosterone (T) in male and female red-spotted newts (Notophthalmus viridescens). First, we evaluated if chemical cues from a male-biased sex ratio affect activity and CORT release rates in females. We predicted that females exposed to chemical cues of three males would be less active and have higher CORT release rates than those exposed to chemical cues of one male. Second, we measured CORT release rates of red-spotted newts in field enclosures with either a male-biased or a female-biased sex ratio. We predicted that females in the male-biased treatment would have higher CORT and T release rates than those in a female-biased treatment, owing to higher levels of male harassment. We also predicted that males would have higher CORT and T release rates in male-biased treatments due to higher levels of male-male competition. Females were not less active in response to chemical cues from more males over fewer males, but there was a positive relationship between female activity and CORT when they were exposed to the cues of three males. We also found that females, but not males, in the male-biased sex ratio treatment had higher CORT and T release rates than those in the female-biased treatment. Our results support the hypothesis that a male-biased sex ratio leads to a higher stress response, which may underlie the observed decrease in immune function and body condition in previous work exposing female red-spotted newts to a male-biased sex ratio. This study furthers our understanding of the mechanistic basis for costs associated with a male-biased sex ratio in a pond-breeding amphibian. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparison of male reproductive success in malaria-refractory and susceptible strains of Anopheles gambiae

PubMed Central

Voordouw, Maarten J; Koella, Jacob C; Hurd, Hilary

2008-01-01

Background In female mosquitoes that transmit malaria, the benefits of being refractory to the Plasmodium parasite are balanced by the immunity costs in the absence of infection. Male mosquitoes, however, gain no advantage from being refractory to blood-transmitted parasites, so that any costs associated with an enhanced immune system in the males limit the evolution of female refractoriness and has practical implications for the release of transgenic males. Methods Aspects of the male cost of carrying Plasmodium-refractory genes were estimated by comparing the males' immune response and reproductive success among strains of Anopheles gambiae that had been selected for refractoriness or extreme susceptibility to the rodent malaria parasite, Plasmodium yoelii nigeriensis. The refractory males had a stronger melanization response than males from the susceptible line. Four traits were used as correlates of a male's reproductive success: the proportion of females that were inseminated by a fixed number of males in a cage within a fixed time frame, the proportion of females with motile sperm in their spermathecae, the proportion of ovipositing females, and the mean number of eggs per batch. Results Although there were significant differences among groups of males in sperm motility and oviposition success, these differences in male reproductive success were not associated with the refractory or susceptible male genotypes. Contrary to expectation, females mated to early emerging refractory males laid significantly more eggs per batch than females mated to later emerging susceptible males. Sperm motility and oviposition success were strongly correlated suggesting that variation in sperm motility influences female oviposition and ultimately male reproductive success. Conclusion An increased melanization response in male A. gambiae does not diminish male reproductive success under the experimental protocol used in this study. That refractory males induced ovipositing females to lay more eggs than susceptible males is an interesting result for any strategy considering the release of transgenic males. That sperm motility influences female oviposition is also important for the release of transgenic males. PMID:18534029

Responses of female rock lizards to multiple scent marks of males: effects of male age, male density and scent over-marking.

PubMed

Martín, José; López, Pilar

2013-03-01

Scent-marked substrates may inform conspecifics on the characteristics of territorial males. Scent-marks of male Carpetan rock lizards (Iberolacerta cyreni) affect space use of females, which by selecting an area may increase the probability of mating with the male that has scent-marked that area. However, males do not hold exclusive territories, and scent-marks of different individual males are often together. This may provide complex information from multiple sources on the social structure. Here, we examined female preference in response to scent marks of various males and combinations in a laboratory experiment. Females preferred areas scent-marked by territorial old males against those scent-marked by young satellite-sneaker males. This reflected the known preference of females for mating with old males. In a second experiment, females preferred areas scent-marked by two males to areas of similar size marked by a single male. This may increase the probability of obtaining multiple copulations with different males, which may favour sperm competition and cryptic female choice, or may be a way to avoid infertile males. Finally, when we experimentally over-marked the scent-marks of an old male with scent-marks of a young male, females did not avoid, nor prefer, the over-marked area, suggesting that the quality of the old male may override the presence of a satellite male. We suggest that, irrespective of the causes underlying why a female selects a scent-marked area, this strategy may affect her reproductive success, which may have the same evolutionary consequences that "direct" mate choice decisions of other animals. Copyright © 2013 Elsevier B.V. All rights reserved.

Using video playback to study the effect of an audience on male mating behavior in the Sailfin molly (Poecilia latipinna).

PubMed

Makowicz, A M; Plath, M; Schlupp, I

2010-09-01

Sexual conflict in poeciliid fishes is well-documented, particularly male sexual harassment and its effects on females. For instance, male attempts to force copulations influence female feeding, energy allocation, and preference for shoaling partners. However, there has been little research conducted to determine how the social environment shapes the occurrence and intensity of sexual harassment. In this study we ask whether an audience male influences the sexual behaviors of a focal male, the correlated feeding time reduction of female Poecilia latipinna, and if the size of the audience male (larger or smaller than the focal male) influences these behaviors. We presented a video of a male, either smaller or larger than the focal male, or an empty tank (control) to a female interacting with a male or female partner and measured feeding times and sexual behaviors. We found that male sexual behaviors increased in the presence of an audience male, especially if the audience male was larger than the focal male. Females fed more in the presence of a partner female than in the presence of a male, which was independent of the audience (i.e., video treatment). Focal female aggression towards the partner female increased with the size of the audience male. The present study shows that an audience male has multiple interacting influences on both male and female behavior. Copyright 2010 Elsevier B.V. All rights reserved.

Does fin coloration signal social status in a dominance hierarchy of the livebearing fish Xiphophorus variatus?

PubMed

Culumber, Zachary W; Monks, Scott

2014-09-01

In each population of the livebearing fish Xiphophorus variatus, only a small portion of the adult males develop bright yellow-red (YR) coloration on the dorsal and caudal fins. Here we characterized the dominance hierarchy in X. variatus and tested whether YR coloration is related to a male's position in the hierarchy and can therefore serve as a reliable cue to rival males. Populations varied considerably in the frequency of YR males. Across all populations, males with YR coloration were significantly larger than the rest of the males in the population. Observations of aggressive interactions among males in small groups in the laboratory revealed a sized-based dominance hierarchy with YR males at the top. Aggression was more common among males of a similar size and fighting increased as male body size differences decreased. However, despite the reliability of YR coloration as a signal of dominance status, males at lower social ranks did not avoid aggression with YR males and YR males did not experience fewer aggressive attacks compared to non-YR males. Our findings demonstrate that fin coloration is a reliable cue of a male's social status but rival males appear to not use this information to avoid potentially costly interactions with dominant males, suggesting that YR fin coloration has not evolved as a cue in agonistic interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

Sexual Selection on male cuticular hydrocarbons via male-male competition and female choice.

PubMed

Lane, S M; Dickinson, A W; Tregenza, T; House, C M

2016-07-01

Traditional views of sexual selection assumed that male-male competition and female mate choice work in harmony, selecting upon the same traits in the same direction. However, we now know that this is not always the case and that these two mechanisms often impose conflicting selection on male sexual traits. Cuticular hydrocarbons (CHCs) have been shown to be linked to both social dominance and male attractiveness in several insect species. However, although several studies have estimated the strength and form of sexual selection imposed on male CHCs by female mate choice, none have established whether these chemical traits are also subject to sexual selection via male-male competition. Using a multivariate selection analysis, we estimate and compare sexual selection exerted by male-male competition and female mate choice on male CHC composition in the broad-horned flour beetle Gnatocerus cornutus. We show that male-male competition exerts strong linear selection on both overall CHC abundance and body size in males, while female mate choice exerts a mixture of linear and nonlinear selection, targeting not just the overall amount of CHCs expressed but the relative abundance of specific hydrocarbons as well. We discuss the potential implications of this antagonistic selection with regard to male reproductive success. © 2016 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

Spiroplasma infection causes either early or late male killing in Drosophila, depending on maternal host age

NASA Astrophysics Data System (ADS)

Kageyama, Daisuke; Anbutsu, Hisashi; Shimada, Masakazu; Fukatsu, Takema

2007-04-01

Symbiont-induced male-killing phenotypes have been found in a variety of insects. Conventionally, these phenotypes have been divided into two categories according to the timing of action: early male killing at embryonic stages and late male killing at late larval stages. In Drosophila species, endosymbiotic bacteria of the genus Spiroplasma have been known to cause early male killing. Here, we report that a spiroplasma strain normally causing early male killing also induces late male killing depending on the maternal host age: male-specific mortality of larvae and pupae was more frequently observed in the offspring of young females. As the lowest spiroplasma density and occasional male production were also associated with newly emerged females, we proposed the density-dependent hypothesis for the expression of early and late male-killing phenotypes. Our finding suggested that (1) early and late male-killing phenotypes can be caused by the same symbiont and probably by the same mechanism; (2) late male killing may occur as an attenuated expression of early male killing; (3) expression of early and late male-killing phenotypes may be dependent on the symbiont density, and thus, could potentially be affected by the host immunity and regulation; and (4) early male killing and late male killing could be alternative strategies adopted by microbial reproductive manipulators.

No evidence for faster male hybrid sterility in population crosses of an intertidal copepod (Tigriopus californicus).

PubMed

Willett, Christopher S

2008-06-01

Two different forces are thought to contribute to the rapid accumulation of hybrid male sterility that has been observed in many inter-specific crosses, namely the faster male and the dominance theories. For male heterogametic taxa, both faster male and dominance would work in the same direction to cause the rapid evolution of male sterility; however, for taxa lacking differentiated sex chromosomes only the faster male theory would explain the rapid evolution of male hybrid sterility. It is currently unknown what causes the faster evolution of male sterility, but increased sexual selection on males and the sensitivity of genes involved in male reproduction are two hypotheses that could explain the observation. Here, patterns of hybrid sterility in crosses of genetically divergent copepod populations are examined to test potential mechanisms of faster male evolution. The study species, Tigriopus californicus, lacks differentiated, hemizygous sex chromosomes and appears to have low levels of divergence caused by sexual selection acting upon males. Hybrid sterility does not accumulate more rapidly in males than females in these crosses suggesting that in this taxon male reproductive genes are not inherently more prone to disruption in hybrids.

Nuclear-cytoplasmic male-sterility in diploid dandelions.

PubMed

van der Hulst, R G M; Meirmans, P; van Tienderen, P H; van Damme, J M M

2004-07-01

Male-sterility was found in diploid dandelions from two widely separated populations from France, and its inheritance was analysed by crossing a diploid male-sterile dandelion to diploid sexuals and triploid apomicts. Nuclear genetic variation, found in full-sib families, segregated for male-fertility, partial male-sterility, and full male-sterility, and also segregated for small-sized versus normally sized pollen. The crossing results are best explained by a cytoplasmic male-sterility factor in combination with two dominant restorer genes. Involvement of the cytoplasmic male-sterility factor was further investigated by chloroplast haplotyping. Male-sterility was exclusively associated with a rare chloroplast haplotype (designated 16b). This haplotype was found in seven male-sterile plants and one (apparently restored) male-fertile individual but does not occur in 110 co-existing male-fertile plants and not in several hundreds of individuals previously haplotyped. Apomicts with cytoplasmic male sterility were generated in some test crosses. This raises the question as to whether the male sterility found in natural dandelion apomicts, is of cytoplasmic or of nuclear genetic nature. As many breeding systems in Taraxacum are involved in shaping population structure, it will be difficult to predict the evolutionary consequences of nuclear-cytoplasmic male-sterility for this species complex.

Relative importance of male and territory quality in pairing success of male rock ptarmigan (Lagopus mutus)

USGS Publications Warehouse

Bart, Jonathan; Earnst, Susan L.

1999-01-01

We studied pairing success in male rock ptarmigan (Lagopus mutus) in northern Alaska to learn whether males obtaining more females possessed phenotypic traits that influenced female choice directly, whether these traits permitted males to obtain territories favored by females, or whether both processes occurred. The number of females per male varied from zero to three. Several male and territory traits were significantly correlated with number of females per male. We used multiple regression to obtain a single measure of male quality and a single measure of territory quality. These measures of male and territory quality correlated with each other and with male pairing success. We used path analysis to separate direct effects of male quality on pairing success from indirect effects due to high-quality males obtaining high-quality territories. Both direct and indirect pathways had significant effects on pairing success, and direct and indirect effects of male traits on pairing success were about equal. This study illustrates an analytical approach for estimating the relative importance of direct and indirect causal relationships in natural systems.

Sexual selection favours male parental care, when females can choose

PubMed Central

Alonzo, Suzanne H.

2012-01-01

Explaining the evolution of male care has proved difficult. Recent theory predicts that female promiscuity and sexual selection on males inherently disfavour male care. In sharp contrast to these expectations, male-only care is often found in species with high extra-pair paternity and striking variation in mating success, where current theory predicts female-only care. Using a model that examines the coevolution of male care, female care and female choice; I show that inter-sexual selection can drive the evolution of male care when females are able to bias mating or paternity towards parental males. Surprisingly, female choice for parental males allows male care to evolve despite low relatedness between the male and the offspring in his care. These results imply that predicting how sexual selection affects parental care evolution will require further understanding of why females, in many species, either do not prefer or cannot favour males that provide care. PMID:22171082

Interdependent effects of male and female body size plasticity on mating behaviour of predatory mites.

PubMed

Walzer, Andreas; Schausberger, Peter

2015-02-01

The adaptive canalization hypothesis predicts that traits with low phenotypic plasticity are more fitness relevant, because they have been canalized via strong past selection, than traits with high phenotypic plasticity. Based on differing male body size plasticities of the predatory mites Phytoseiulus persimilis (low plasticity) and Neoseiulus californicus (high plasticity), we accordingly hypothesized that small male body size entails higher costs in female choice and male-male competition in P. persimilis than N. californicus . Males of both species are highly polygynous but females differ in the level of polyandry (low level in P. persimilis ; medium level in N. californicus ). We videotaped the mating interactions in triplets of either P. persimilis or N. californicus , consisting of a virgin female (small or standard-sized) and a small and a standard-sized male. Mating by both small and standard-sized P. persimilis females was biased towards standard-sized males, resulting from the interplay between female preference for standard-sized males and the inferiority of small males in male-male competition. In contrast, mating by N. californicus females was equally balanced between small and standard-sized males. Small N. californicus males were more aggressive ('Napoleon complex') in male-male competition, reducing the likelihood of encounter between the standard-sized male and the female, and thus counterbalancing female preference for standard-sized males. Our results support the hypothesis that male body size is more important to fitness in the low-level polyandrous P. persimilis than in the medium-level polyandrous N. californicus and provide a key example of the implications of sexually selected body size plasticity on mating behaviour.

Differential investment into testes and sperm production in alternative male reproductive tactics of the African striped mouse (Rhabdomys pumilio).

PubMed

Schradin, Carsten; Eder, Susanne; Müller, Karin

2012-05-01

Males that follow alternative reproductive tactics might differ in their investment into testis development and sperm production. The resource-allocation hypothesis predicts that males following a sneaker tactic should invest more into sperm production than dominant territorial males which should invest more into mate guarding. This hypothesis is supported by studies in species where individual males cannot switch between tactics (fixed tactics). Here we present the first data for a species where males can switch between tactics (plastic tactics). We studied African striped mice (Rhabdomys pumilio) in captivity, mimicking three tactics observed in the field: philopatric group-living males, singly-housed males representing roaming males, and group-living breeding males. We measured quantitative and qualitative reproductive traits, as well as serum and testis hormone concentrations. We found no support for the resource-allocation hypothesis, since breeding and singly-housed males invested similarly in testes and sperm. However, philopatric males had significantly smaller testes and epididymides, lower sperm counts, lower testosterone and higher corticosterone levels than males of the two other tactics. Philopatric males did not reach a larger body mass than singly-housed males with well developed reproductive traits, indicating that they did not trade investment in sperm production against growth. Interestingly, testis testosterone concentrations of philopatric males did not differ from those of other males. Our data suggest that philopatric males are reproductively suppressed by the breeding male, but might be ready to increase their serum testosterone levels when social and environmental conditions allow for this physiological switch accompanying the behavioral switch between tactics. Copyright © 2012 Elsevier Inc. All rights reserved.

Male behaviors reveal multiple pherotypes within vine mealybug Planococcus ficus (Signoret) (Hemiptera; Pseudococcidae) populations

NASA Astrophysics Data System (ADS)

Kol-Maimon, Hofit; Levi-Zada, Anat; Franco, José Carlos; Dunkelblum, Ezra; Protasov, Alex; Eliyaho, Miriam; Mendel, Zvi

2010-12-01

The vine mealybug (VM) females collected in Israel produce two sex pheromone compounds: lavandulyl senecioate (LS) and ( S)-lavandulyl isovalerate (LI). The males display ambiguous behavior to LI: repulsion in the vineyard and attraction of laboratory-reared males. We addressed the question of individual male behavior, i.e., do males respond to both LS and LI, or might they display a distinct response to each of the two pheromone compounds. We compared male pherotype frequencies between wild-caught and laboratory-reared populations. Then, we examined the relationship between pherotype composition and male capture rates in pheromone traps. Finally, we addressed the heredity of the pherotypes. The Israeli VM populations contain nine different male pherotypes, as defined according to the male behavior to pheromone compounds. The studied Portuguese populations included five of the nine pherotypes; none of the Portuguese males were attracted to LI. It seems that the high frequency of males that were attracted to LI is related to dense VM populations. It is hypothesized that selection for the male pherotypes, I males, those that respond to LI, occur under high-density rearing conditions. This may result from shorter development times of males and females that produce more I male pherotypes. The lower relative frequency of trapping of males in LI-baited traps than expected from the percentage determined in a Petri dish arena suggests that males that respond solely to LS (S males) are better fliers. The results also suggest that the pherotype trait is inherited by both sexes of the VM.

Males collectively defend their one-male units against bachelor males in a multi-level primate society.

PubMed

Xiang, Zuo-Fu; Yang, Bang-He; Yu, Yang; Yao, Hui; Grueter, Cyril C; Garber, Paul A; Li, Ming

2014-07-01

Group-level male-male co-operation, which has been documented in several primate and non-primate societies, may be mutualistically advantageous to the participants when confronted with threats such as takeovers and cuckoldry by external males. Co-operation among members of distinct social units-while universal among humans-is extremely rare in non-human primates. We present the first observations of collective action or co-operation among males of different one-male units (OMU) in a multi-level society of Rhinopithecus roxellana. A total of 59 instances of male co-operation were recorded. Male co-operation included coordinated chasing, joint vigilance, and patrolling behavior directed at lone adult males trying to enter an OMU. Male co-operation was significantly more frequent during the mating season when the risk of incursions and extra-group paternity was higher. Paternity of infants born in the subsequent birth season and kin relationships among resident males were identified using microsatellite genotype. All infants were sired by OMU males, which we interpret as possible evidence for their success at thwarting mating attempts by satellite males. OMU males were principally unrelated suggesting that male co-operation is best understood in terms of the mutual direct benefits individuals obtain through collective action. Our findings lend support to the bachelor threat hypothesis in which the cooperative behavior of several individuals is more effective than the lone action of a single individual in providing mate defense. Our research has implications for understanding male bonding, higher-level collective action, and the evolution of social co-operation in human societies. © 2013 Wiley Periodicals, Inc.

Male dominance rank and reproductive success in chimpanzees, Pan troglodytes schweinfurthii.

PubMed

Wroblewski, Emily E; Murray, Carson M; Keele, Brandon F; Schumacher-Stankey, Joann C; Hahn, Beatrice H; Pusey, Anne E

2009-01-01

Competition for fertile females determines male reproductive success in many species. The priority of access model predicts that male dominance rank determines access to females, but this model has been difficult to test in wild populations, particularly in promiscuous mating systems. Tests of the model have produced variable results, probably because of the differing socioecological circumstances of individual species and populations. We tested the predictions of the priority of access model in the chimpanzees of Gombe National Park, Tanzania. Chimpanzees are an interesting species in which to test the model because of their fission-fusion grouping patterns, promiscuous mating system and alternative male mating strategies. We determined paternity for 34 offspring over a 22-year period and found that the priority of access model was generally predictive of male reproductive success. However, we found that younger males had higher success per male than older males, and low-ranking males sired more offspring than predicted. Low-ranking males sired offspring with younger, less desirable females and by engaging in consortships more often than high-ranking fathers. Although alpha males never sired offspring with related females, inbreeding avoidance of high-ranking male relatives did not completely explain the success of low-ranking males. While our work confirms that male rank typically predicts male chimpanzee reproductive success, other factors are also important; mate choice and alternative male strategies can give low-ranking males access to females more often than would be predicted by the model. Furthermore, the success of younger males suggests that they are more successful in sperm competition.

Costs of female odour in males of the parasitic wasp Lariophagus distinguendus (Hymenoptera: Pteromalidae)

NASA Astrophysics Data System (ADS)

Ruther, Joachim; Steiner, Sven

2008-06-01

The display of female traits by males is widespread in the animal kingdom. In several species, this phenomenon has been shown to function adaptively as a male mating strategy to deceive sexual rivals (female mimicry). Freshly emerged males of the parasitic wasp Lariophagus distinguendus (Hymenoptera: Pteromalidae) are perceived by other males as if they were females because of a very similar composition of cuticular hydrocarbons which function as a sex pheromone in this species inducing courtship behaviour in males. Within 32 h, however, males deactivate the pheromone and are no longer courted by other males. In this paper, behavioural experiments were performed to test hypotheses on potential costs and benefits associated with the female odour in young males. We did not find any benefits, but demonstrated that young males were significantly more often outrivaled in male-male contests when competing with two older males for a female. Also, young males were significantly more often mounted in homosexual courtship events during these contests. Thus, display of female traits by males is not necessarily beneficial, and in fact, can be disadvantageous. We suggest that these costs have favoured the evolution of the pheromone deactivation mechanism in L. distinguendus males. The function of cuticular hydrocarbons as a female courtship pheromone in L. distinguendus might have evolved secondarily from a primary function relevant for both genders, and the deactivation of the signal in males might have caused a shift of specificity of the chemical signal from the species level to the sex level.

Body Size Correlates with Fertilization Success but not Gonad Size in Grass Goby Territorial Males

PubMed Central

Pujolar, Jose Martin; Locatello, Lisa; Zane, Lorenzo; Mazzoldi, Carlotta

2012-01-01

In fish species with alternative male mating tactics, sperm competition typically occurs when small males that are unsuccessful in direct contests steal fertilization opportunities from large dominant males. In the grass goby Zosterisessor ophiocephalus, large territorial males defend and court females from nest sites, while small sneaker males obtain matings by sneaking into nests. Parentage assignment of 688 eggs from 8 different nests sampled in the 2003–2004 breeding season revealed a high level of sperm competition. Fertilization success of territorial males was very high but in all nests sneakers also contributed to the progeny. In territorial males, fertilization success correlated positively with male body size. Gonadal investment was explored in a sample of 126 grass gobies collected during the period 1995–1996 in the same area (61 territorial males and 65 sneakers). Correlation between body weight and testis weight was positive and significant for sneaker males, while correlation was virtually equal to zero in territorial males. That body size in territorial males is correlated with fertilization success but not gonad size suggests that males allocate much more energy into growth and relatively little into sperm production once the needed size to become territorial is attained. The increased paternity of larger territorial males might be due to a more effective defense of the nest in comparison with smaller territorial males. PMID:23056415

Body size correlates with fertilization success but not gonad size in grass goby territorial males.

PubMed

Pujolar, Jose Martin; Locatello, Lisa; Zane, Lorenzo; Mazzoldi, Carlotta

2012-01-01

In fish species with alternative male mating tactics, sperm competition typically occurs when small males that are unsuccessful in direct contests steal fertilization opportunities from large dominant males. In the grass goby Zosterisessor ophiocephalus, large territorial males defend and court females from nest sites, while small sneaker males obtain matings by sneaking into nests. Parentage assignment of 688 eggs from 8 different nests sampled in the 2003-2004 breeding season revealed a high level of sperm competition. Fertilization success of territorial males was very high but in all nests sneakers also contributed to the progeny. In territorial males, fertilization success correlated positively with male body size. Gonadal investment was explored in a sample of 126 grass gobies collected during the period 1995-1996 in the same area (61 territorial males and 65 sneakers). Correlation between body weight and testis weight was positive and significant for sneaker males, while correlation was virtually equal to zero in territorial males. That body size in territorial males is correlated with fertilization success but not gonad size suggests that males allocate much more energy into growth and relatively little into sperm production once the needed size to become territorial is attained. The increased paternity of larger territorial males might be due to a more effective defense of the nest in comparison with smaller territorial males.

The evolution of males: support for predictions from sex allocation theory using mating arrays of sagittaria latifolia (alismataceae).

PubMed

Perry, Laura E; Dorken, Marcel E

2011-10-01

Investment in male function should often yield diminishing fitness returns, subjecting the evolution of male phenotypes to substantial constraints. In plants, the subdivision of male function via the gradual presentation of pollen might minimize these constraints by preventing the saturation of receptive stigmas. Here, we report on an investigation of (1) patterns of investment in male function by plants in hermaphroditic (monoecious) and dioecious populations of Sagittaria latifolia, and (2) patterns of siring success by males versus hermaphrodites in experimental mating arrays. We show that in natural populations, males from dioecious populations had greater investment in male function than hermaphrodites in monoecious populations. However, as a proportion of total flower production, males presented substantially fewer flowers at once than hermaphrodites. In comparison with hermaphrodites, therefore, males prolonged the period over which they presented pollen. In mating arrays comprised of females, males, and hermaphrodites, siring success by males increased linearly with flower production. This finding is consistent with the existence of a linear gain curve for male function in S. latifolia and supports the idea that the gradual deployment of male function enables plants to avoid diminishing returns on the investment in male function. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Paternity and kin structure among neighbouring groups in wild bonobos at Wamba.

PubMed

Ishizuka, Shintaro; Kawamoto, Yoshi; Sakamaki, Tetsuya; Tokuyama, Nahoko; Toda, Kazuya; Okamura, Hiroki; Furuichi, Takeshi

2018-01-01

Although both bonobos and chimpanzees are male-philopatric species, outcomes of male-male reproductive competition seem to be more closely associated with mating success in chimpanzees. This suggests that the extent of male reproductive skew is lower in bonobos. In addition, between-group male-male reproductive competition is more lethal in chimpanzees. This suggests that between-group differentiation in male kinship is lower in bonobos. We analysed the paternity of 17 offspring in two bonobo groups and estimated the relatedness of individuals among three neighbouring groups by using DNA extracted from non-invasive samples at Wamba, in the Democratic Republic of the Congo. The alpha males sired at least nine of 17 offspring. This supports a previous finding that the male reproductive skew is higher in bonobos than that in chimpanzees. Average relatedness among males within groups was significantly higher than that among males across groups, whereas there was no significant difference among females between within and across groups. These results are consistent with male philopatry, highly skewed reproductive success of males and female dispersal. Higher average relatedness among males within groups suggest that the differences in hostility towards males of different groups between bonobos and chimpanzees may be explained by factors other than kinship.

Age-dependent male mating tactics in a spider mite-A life-history perspective.

PubMed

Sato, Yukie; Rühr, Peter T; Schmitz, Helmut; Egas, Martijn; Blanke, Alexander

2016-10-01

Males often fight with rival males for access to females. However, some males display nonfighting tactics such as sneaking, satellite behavior, or female mimicking. When these mating tactics comprise a conditional strategy, they are often thought to be explained by resource holding potential (RHP), that is, nonfighting tactics are displayed by less competitive males who are more likely to lose a fight. The alternative mating tactics, however, can also be explained by life-history theory, which predicts that young males avoid fighting, regardless of their RHP, if it pays off to wait for future reproduction. Here, we test whether the sneaking tactic displayed by young males of the two-spotted spider mite can be explained by life-history theory. We tested whether young sneaker males survive longer than young fighter males after a bout of mild or strong competition with old fighter males. We also investigated whether old males have a more protective outer skin-a possible proxy for RHP-by measuring cuticle hardness and elasticity using nanoindentation. We found that young sneaker males survived longer than young fighter males after mild male competition. This difference was not found after strong male competition, which suggests that induction of sneaking tactic is affected by male density. Hardness and elasticity of the skin did not vary with male age. Given that earlier work could also not detect morphometric differences between fighter and sneaker males, we conclude that there is no apparent increase in RHP with age in the mite and age-dependent male mating tactics in the mite can be explained only by life-history theory. Because it is likely that fighting incurs a survival cost, age-dependent alternative mating tactics may be explained by life-history theory in many species when reproduction of old males is a significant factor in fitness.

Reduction of dopamine level enhances the attractiveness of male Drosophila to other males.

PubMed

Liu, Tong; Dartevelle, Laurence; Yuan, Chunyan; Wei, Hongping; Wang, Ying; Ferveur, Jean-François; Guo, Aike

2009-01-01

Dopamine is an important neuromodulator in animals and its roles in mammalian sexual behavior are extensively studied. Drosophila as a useful model system is widely used in many fields of biological studies. It has been reported that dopamine reduction can affect female receptivity in Drosophila and leave male-female courtship behavior unaffected. Here, we used genetic and pharmacological approaches to decrease the dopamine level in dopaminergic cells in Drosophila, and investigated the consequence of this manipulation on male homosexual courtship behavior. We find that reduction of dopamine level can induce Drosophila male-male courtship behavior, and that this behavior is mainly due to the increased male attractiveness or decreased aversiveness towards other males, but not to their enhanced propensity to court other males. Chemical signal input probably plays a crucial role in the male-male courtship induced by the courtees with reduction of dopamine. Our finding provides insight into the relationship between the dopamine reduction and male-male courtship behavior, and hints dopamine level is important for controlling Drosophila courtship behavior.

Reduction of Dopamine Level Enhances the Attractiveness of Male Drosophila to Other Males

PubMed Central

Liu, Tong; Dartevelle, Laurence; Yuan, Chunyan; Wei, Hongping; Wang, Ying; Ferveur, Jean-François; Guo, Aike

2009-01-01

Dopamine is an important neuromodulator in animals and its roles in mammalian sexual behavior are extensively studied. Drosophila as a useful model system is widely used in many fields of biological studies. It has been reported that dopamine reduction can affect female receptivity in Drosophila and leave male-female courtship behavior unaffected. Here, we used genetic and pharmacological approaches to decrease the dopamine level in dopaminergic cells in Drosophila, and investigated the consequence of this manipulation on male homosexual courtship behavior. We find that reduction of dopamine level can induce Drosophila male-male courtship behavior, and that this behavior is mainly due to the increased male attractiveness or decreased aversiveness towards other males, but not to their enhanced propensity to court other males. Chemical signal input probably plays a crucial role in the male-male courtship induced by the courtees with reduction of dopamine. Our finding provides insight into the relationship between the dopamine reduction and male-male courtship behavior, and hints dopamine level is important for controlling Drosophila courtship behavior. PMID:19238209

BODY SIZE AND HAREM SIZE IN MALE RED-WINGED BLACKBIRDS: MANIPULATING SELECTION WITH SEX-SPECIFIC FEEDERS.

PubMed

Rohwer, Sievert; Langston, Nancy; Gori, Dave

1996-10-01

We experimentally manipulated the strength of selection in the field on red-winged blackbirds (Agelaius phoeniceus) to test hypotheses about contrasting selective forces that favor either large or small males in sexually size dimorphic birds. Selander (1972) argued that sexual selection favors larger males, while survival selection eventually stabilizes male size because larger males do not survive as well as smaller males during harsh winters. Searcy (1979a) proposed instead that sexual selection may be self limiting: male size might be stabilized not by overwinter mortality, but by breeding-season sexual selection that favors smaller males. Under conditions of energetic stress, smaller males should be able to display more and thus achieve higher reproductive success. Using feeders that provisioned males or females but not both, we produced conditions that mimicked the extremes of natural conditions. We found experimental support for the hypothesis that when food is abundant, sexual selection favors larger males. But even under conditions of severe energetic stress, smaller males did not gain larger harems, as the self-limiting hypothesis predicted. Larger males were more energetically stressed than smaller males, but in ways that affected their future reproductive output rather than their current reproductive performance. Stressed males that returned had smaller wings and tails than those that did not return; among returning stressed males, relative harem sizes were inversely related to wing and tail length. Thus, male body size may be stabilized not by survival costs during the non-breeding season, nor by energetic costs during the breeding season, but by costs of future reproduction that larger males pay for their increased breeding-season effort. © 1996 The Society for the Study of Evolution.

Alternative male reproductive tactics and the immunocompetence handicap in the Azorean rock-pool blenny, Parablennius parvicornis

PubMed Central

Ros, Albert F.H; Bouton, Niels; Santos, Ricardo S; Oliveira, Rui F

2006-01-01

In the Azorean rock-pool blenny (Parablennius parvicornis) reproductively active males display alternative morphotypes, which differ in the expression of secondary sexual characters (SSC). Males expressing SSC, the M+ morphotype, have high androgen levels and compete for crevices that will be visited by females to spawn. M+ males holding nests court females and care for the eggs. Males with low expression of SSC, the M− morphotype, have low levels of androgens and reproduce by stealing fertilizations from the M+ males. Based on the hypothesis that androgens are immunosuppressive, we expected these morphotypes to differ in immunocompetence. To test this hypothesis, we conducted a field study in which we collected repeated blood samples to monitor leukocyte populations (blood smears), and to measure the primary antibody response of males that were experimentally challenged with a foreign non-pathogenic antigen (sheep red blood cells). Circulating levels of 11-ketotestosterone and testosterone were higher in M+ males than in M− males. Neither granulocyte nor thrombocyte counts did covariate with androgens or male tactic. In contrast, lymphocyte counts and humoral antibody response were negatively correlated with body size, and as expected, both were lower in M+ than in M− males. Interestingly, in M+ males androgen levels decreased after immunization, and this was less in nest-holder males than in M+ males that were floating around in the pools. Within each morphotype we found no relationship between androgens and immunocompetence. The latter result is not supportive for androgen regulated immunosuppression in M+ males. A possible alternative is enhancement of immunity in M− males. These males had relatively high levels of injuries in comparison with M+ males. High immunity might be a consequence of high infection rate because of such injuries. PMID:16627274

Rare male aggression directed toward females in a female-dominated society: Baiting behavior in the spotted hyena

USGS Publications Warehouse

Szykman, Micaela; Engh, Anne L.; Van Horn, Russell C.; Boydston, Erin E.; Scribner, Kim T.; Holekamp, Kay E.

2003-01-01

Spotted hyenas (Crocuta crocuta) are gregarious carnivores. The females are socially dominant to males, and adult males rarely direct aggression toward adult females. This study analyzed all cases in which adult immigrant males behaved aggressively toward adult females in a large population of free-living hyenas in Kenya, observed for 11 years. Our goals were to describe the conditions under which male attacks on females occur, and address possible adaptive functions. Most aggression directed by adult immigrant males against females occurred when coalitions of two or more males attacked a single adult female, who typically responded by defending herself and fighting back. Male aggression against females frequently occurred at sites of ungulate kills, but males never behaved aggressively toward females over food, and all male attacks on females were unprovoked. Although no mounting or other copulatory behaviors ever occurred during or immediately after an attack, the number of male attacks on females peaked around the time of conception. Daily rates at which males attacked females did not vary with female social rank. However, daily attack rates did vary significantly with female reproductive state, and the highest rates of male attack on females were observed during the two stages of the reproductive cycle during which females were most likely to conceive litters. The adaptive significance of male aggression against females in this species remains unknown, but a tight association between male attacks on females and a female's time of conception provides strong evidence of some role for male aggression in hyena sexual behavior. In particular, our data are consistent with hypotheses suggesting that male aggression toward females in this species either serves to inform females about male fitness or represents sexual harassment.

Males adjust their signalling behaviour according to experience of male signals and male-female signal duets.

PubMed

Rebar, D; Rodríguez, R L

2016-04-01

Sexual signals are conspicuous sources of information about neighbouring competitors, and species in which males and females signal during pair formation provide various sources of public information to which individuals can adjust their behaviour. We performed two experiments with a duetting vibrational insect, Enchenopa binotata treehoppers (Hemiptera: Membracidae), to ask whether males adjust their signalling behaviour according to (1a) their own experience of competitors' signals, (1b) how females adjust their mate preferences on the basis of their experience of male signals (described in prior work), and/or (2) their own experience of female response signals to competitors' signals. We presented males with synthetic male signals of different frequencies and combinations thereof for 2 weeks. We recorded males a day after their last signal exposure, finding that (1a) male signal rate increased in response to experience of attractive competitors, but that (1b) male signal frequency did not shift in a manner consistent with how females adjust their mate preferences in those experience treatments. Second, we presented males with different male-female duets for 2 weeks, finding that (2) male signal length increased from experience of female duets with attractive competitors. Males thus make two types of adjustment according to two sources of public information: one provided by experience of male signals and another by experience of female responses to male signals. Signalling plasticity can generate feedback loops between the adjustments that males and females make, and we discuss the potential consequences of such feedback loops for the evolution of communication systems. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Effect of chronic glomerulonephritis on the semen quality and cytokines in the semen of infertile males.

PubMed

Zhang, Huina; Ying, Yingfen; Chen, Yilu; Lu, Xiaosheng; Huang, Yonggang

2017-01-01

The effects of chronic glomerulonephritis (CGN) on semen quality and cytokine levels in the semen of infertile males remain undetermined. Fifty-eight semen samples from normal males and CGN males with and without infertility, respectively, were analyzed. Semen volume, semen pH, sperm density, percentage of forward movement of sperm, sperm activate rate, sperm survival rate, and rate of normal sperm morphology of infertility males with CGN were significantly lower than those of CGN males without infertility and normal males (P<.05). In addition, the blood urea nitrogen and serum creatinine levels and interleukin (IL)-17 and IL-18 levels in infertility males with CGN were significantly higher than those of CGN males without infertility and normal males (P<.05). CGN increased the blood urea nitrogen and serum creatinine levels, which induced abnormal expression of IL-17 and IL-18, and negatively affected male semen quality and might result in male infertility. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cost of reproduction in Callosobruchus maculatus: effects of mating on male longevity and the effect of male mating status on female longevity.

PubMed

Paukku, Satu; Kotiaho, Janne S

2005-11-01

One of the most studied life-history trade-offs is that resulting from the cost of reproduction: a trade-off arises when reproduction diverts limited resources from other life-history traits. We examine the cost of reproduction in male, and the effect of male mating status on female Callosobruchus maculatus seed beetles. Cost of reproduction for male C. maculatus was manifested as reduced longevity. There was also a positive relationship between male body size and male longevity. Females mated to males that had already copulated twice did not live as long as females mated to males that had copulated once or not at all. The third copulation of males also lasted longer than the two previous ones. We conclude that even though the cost of reproduction for males has been studied much less than that in females, there is growing evidence that male reproductive effort is more complex than has traditionally been thought.

Male swordtails court with an audience in mind.

PubMed

Fisher, Heidi S; Rosenthal, Gil G

2007-02-22

Females are usually considered to be the target of male courtship behaviour. In nature, however, social interactions rarely occur without other observers; thus, it is conceivable that some male courtship behaviours are directed not towards females, but rather towards male rivals. The northern swordtail, Xiphophorus birchmanni, is a freshwater fish found in high densities in natural streams. Males court by swimming close to and in parallel with the female, raising their large sail-like dorsal fin, and quivering briefly. Here, we show that females prefer males that display small dorsal fins to those with large ones, and that males are less aggressive to other males with large dorsal fins. Male swordtails also raise their dorsal fins more frequently when courting in the presence of other males. These results suggest that, despite female avoidance of large dorsal fins, males that raise their fin during courtship benefit by intimidating potential competitors; the intended receivers of this signal are thus males, not females. Intrasexual selection can therefore offset the forces of intersexual selection, even in a courtship display.

Is male rhesus macaque red color ornamentation attractive to females?

PubMed Central

Dubuc, Constance; Allen, William L.; Maestripieri, Dario; Higham, James P.

2014-01-01

Male sexually-selected traits can evolve through different mechanisms: conspicuous and colorful ornaments usually evolve through inter-sexual selection, while weapons usually evolve through intra-sexual selection. Male ornaments are rare among mammals in comparison to birds, leading to the notion that female mate choice generally plays little role in trait evolution in this taxon. Supporting this view, when ornaments are present in mammals they typically indicate social status and are products of male-male competition. This general mammalian pattern, however, may not apply to rhesus macaques (Macaca mulatta). Males of this species display conspicuous skin coloration, but this expression is not correlated to dominance rank, and is therefore unlikely to have evolved due to male-male competition. Here, we investigate whether male color expression influences female proceptivity towards males in the Cayo Santiago free-ranging rhesus macaque population. We collected face images of 24 adult males varying in dominance rank and age at the peak of the mating season, and modeled these to rhesus macaque visual perception. We also recorded female socio-sexual behaviors towards these males. Results show that dark red males received more sexual solicitations, by more females, than pale pink ones. Together with previous results, our study suggests that male color ornaments are more likely to be a product of inter- rather than intra-sexual selection. This may especially be the case in rhesus macaques due to the particular characteristics of male-male competition in this species. PMID:25246728

Mating and male pheromone kill Caenorhabditis males through distinct mechanisms.

PubMed

Shi, Cheng; Runnels, Alexi M; Murphy, Coleen T

2017-03-14

Differences in longevity between sexes is a mysterious yet general phenomenon across great evolutionary distances. To test the roles of responses to environmental cues and sexual behaviors in longevity regulation, we examined Caenorhabditis male lifespan under solitary, grouped, and mated conditions. We find that neurons and the germline are required for male pheromone-dependent male death. Hermaphrodites with a masculinized nervous system secrete male pheromone and are susceptible to male pheromone killing. Male pheromone-mediated killing is unique to androdioecious Caenorhabditis , and may reduce the number of males in hermaphroditic populations; neither males nor females of gonochoristic species are susceptible to male pheromone killing. By contrast, mating-induced death, which is characterized by germline-dependent shrinking, glycogen loss, and ectopic vitellogenin expression, utilizes distinct molecular pathways and is shared between the sexes and across species. The study of sex- and species-specific regulation of aging reveals deeply conserved mechanisms of longevity and population structure regulation.

Sexual segregation in Roosevelt Elk: Cropping rates and aggression in mixed sex groups

USGS Publications Warehouse

Weckerly, Floyd F.; Ricca, Mark A.; Meyer, Katherin P.

2001-01-01

Few studies of sexual segregation in ruminants have tested widely invoked mechanisms of segregation in mixed-sex groups. In a sexually segregated population of Roosevelt elk (Cervus elaphus roosevelti), we examined if adult males had reduced intake of forage when in mixed-sex groups and if intersexual differences in aggression caused females to avoid males. Based on a mechanistic model of forage intake, animals with lower instantaneous feed intake should have higher cropping rates. Focal animal sampling indicated that adult males and females in summer and winter had similar cropping rates in mixed-sex groups, whereas males in male-only groups had lower rates of cropping than males in mixed-sex groups. Outside the mating season, males in male groups spent proportionally less time ≤1 body length of congenders than females in female groups, and the rate of aggression ≤1 body length was higher for males. Female–female aggression was higher in mixed-sex groups that contained more males than the median proportion of males in mixed-sex groups. Female and mixed-sex groups walked away when groups of males numbering >6 were ≤50 m but did not walk away when male groups ≤50 m had ≤5 individuals. Sexual segregation was associated with behaviors of sexes in mixed-sex groups: reduced intake of forage by males and increased female–female aggression with more males.

Experimental increase of testosterone increases boldness and decreases anxiety in male African striped mouse helpers.

PubMed

Raynaud, Julien; Schradin, Carsten

2014-04-22

Males of many species can adjust their behaviors to environmental conditions by changing reproductive tactics. Testosterone surges in adult breeding males typically inhibit the expression of paternal care while facilitating the expression of aggression during environmental changes. Similarly, in non-breeding philopatric males of cooperatively breeding species, up-regulation of testosterone may inhibit alloparental care while facilitating dispersal, i.e. males might become bolder and more explorative. We tested this hypothesis in philopatric male African striped mice, Rhabdomys pumilio. Striped mouse males can either remain in their natal groups providing alloparental care or they can disperse seeking mating opportunities. Compared to philopatric males, dispersed males typically show higher testosterone levels and lower corticosterone levels, and more aggression toward pups and same sex conspecifics. We experimentally increased the testosterone levels of the philopatric males kept in their family groups when pups were present. Testosterone-treated males did not differ significantly from control males in alloparental care and in aggression toward same-sex conspecifics. Compared to the control males, testosterone treated males were bolder, more active, and less anxious; they also showed lower corticosterone levels. The philopatric males were sensitive to our testosterone treatment for dispersal- and anxiety-like behavior but insensitive for social behaviors. Our results suggest a role of testosterone in dispersal. Copyright © 2014. Published by Elsevier Inc.

Microanatomy and Development of the Dwarf Male of Symbion pandora (Phylum Cycliophora): New Insights from Ultrastructural Investigation Based on Serial Section Electron Microscopy

PubMed Central

Neves, Ricardo Cardoso; Reichert, Heinrich

2015-01-01

Cycliophorans have a complex life cycle that involves several sexual and asexual stages. One of the sexual stages is the 40 μm-long dwarf male, which is among the smallest free-living metazoans. Although the dwarf male has a highly complex body plan, this minute organism is composed of a very low number of somatic cells (~50). The developmental processes that give rise to this unique phenotype are largely unknown. Here we use high resolution serial block face—scanning electron microscopy to analyze the anatomy and morphogenesis of three cycliophoran dwarf males at different developmental stages ranging from internal bud to mature male. The anatomical and morphological features of the mature dwarf male stage reported here largely correspond to those reported in earlier studies. Interestingly, the organs that typically characterize the anatomy of the mature dwarf male, e.g., muscles, brain, testis and glands, are already formed in the young male. However, there are striking differences between the mature male and young male stages at the level of cellular architecture. Thus, while the young male stage, like the internal bud stage, possesses approximately 200 nucleated cells, the mature male stage comprises only around 50 nucleated cells; muscle and epidermal cells of the mature male lack nuclei. Moreover, the total body volume of the mature male is only 63% of the body of the young male implying that the maturation of the young male into a mature male involves a marked reduction of internal body volume, mainly by massive nuclei loss. Our comparative analysis of these dwarf male specimens reveals unprecedented insight into the striking morphological and developmental differences that characterize these highly miniaturized male stages both at the level of body organization and at the level of cellular ultrastructure. PMID:25875482

Augmenting effects of gestational arsenite exposure of C3H mice on the hepatic tumors of the F₂ male offspring via the F₁ male offspring.

PubMed

Nohara, Keiko; Okamura, Kazuyuki; Suzuki, Takehiro; Murai, Hikari; Ito, Takaaki; Shinjo, Keiko; Takumi, Shota; Michikawa, Takehiro; Kondo, Yutaka; Hata, Kenichiro

2016-01-01

Gestational exposure can affect the F2 generation through exposure of F1 germline cells. Previous studies reported that arsenite exposure of only F0 females during their pregnancy increases hepatic tumors in the F1 males in C3H mice, whose males are predisposed spontaneously to develop hepatic tumors later in life. The present study addressed the effects of gestational arsenite exposure on tumorigenesis of the F2 males in C3H mice. Expression analysis of several genes in the normal livers at 53 and 80 weeks of age clearly showed significant changes in the F2 males obtained by crossing gestational arsenite-exposed F1 (arsenite-F1) males and females compared to the control F2 males. Some of the changes were shown to occur in a late-onset manner. Then the tumor incidence was assessed at 75-82 weeks of age in the F2 males obtained by reciprocal crossing between the control and arsenite-F1 males and females. The results demonstrated that the F2 males born to arsenite-F1 males developed tumors at a significantly higher rate than the F2 males born to the control F1 males, irrespective of exposure of F1 females. Gene expressions of hepatocellular carcinoma markers β-catenin (CTNNB1) and interleukin-1 receptor antagonist in the tumors were significantly upregulated in the F2 males born to arsenite-F1 males compared to those born to the control F1 males. These results show that arsenite exposure of only F0 pregnant mice causes late-onset changes and augments tumors in the livers of the F2 males by affecting the F1 male offspring. Copyright © 2015 John Wiley & Sons, Ltd.

Quantitative genetic models of sexual selection by male choice.

PubMed

Nakahashi, Wataru

2008-09-01

There are many examples of male mate choice for female traits that tend to be associated with high fertility. I develop quantitative genetic models of a female trait and a male preference to show when such a male preference can evolve. I find that a disagreement between the fertility maximum and the viability maximum of the female trait is necessary for directional male preference (preference for extreme female trait values) to evolve. Moreover, when there is a shortage of available male partners or variance in male nongenetic quality, strong male preference can evolve. Furthermore, I also show that males evolve to exhibit a stronger preference for females that are more feminine (less resemblance to males) than the average female when there is a sexual dimorphism caused by fertility selection which acts only on females.

The contrasting role of male relatedness in different mechanisms of sexual selection in red junglefowl

PubMed Central

Tan, Cedric Kai Wei; Doyle, Philippa; Bagshaw, Emma; Richardson, David S.; Wigby, Stuart; Pizzari, Tommaso

2017-01-01

In structured populations, competition for reproductive opportunities should be relaxed among related males. The few tests of this prediction often neglect the fact that sexual selection acts through multiple mechanisms, both before and after mating. We performed experiments to study the role of within‐group male relatedness across pre‐ and postcopulatory mechanisms of sexual selection in social groups of red junglefowl, Gallus gallus, in which two related males and one unrelated male competed over females unrelated to all the males. We confirm theoretical expectations that, after controlling for male social status, competition over mating was reduced among related males. However, this effect was contrasted by other sexual selection mechanisms. First, females biased male mating in favor of the unrelated male, and might also favor his inseminations after mating. Second, males invested more—rather than fewer—sperm in postcopulatory competition with relatives. A number of factors may contribute to explain this counterintuitive pattern of sperm allocation, including trade‐offs between male investment in pre‐ versus postcopulatory competition, differences in the relative relatedness of pre‐ versus postcopulatory competitors, and female bias in sperm utilization in response to male relatedness. Collectively, these results reveal that within‐group male relatedness may have contrasting effects in different mechanisms of sexual selection. PMID:27925168

Male sexual ornament size is positively associated with reproductive morphology and enhanced fertility in the stalk-eyed fly Teleopsis dalmanni

PubMed Central

2008-01-01

Background Exaggerated male ornaments and displays often evolve in species where males only provide females with ejaculates during reproduction. Although "good genes" arguments are typically invoked to explain this phenomenon, a simpler alternative is possible if variation in male reproductive quality (e.g. sperm number, ejaculate content, mating rate) is an important determinant of female reproductive success. The "phenotype-linked fertility hypothesis" states that female preference for male ornaments or displays has been selected to ensure higher levels of fertility and has driven the evolution of exaggerated male traits. Females of the stalk-eyed fly Teleopsis dalmanni must mate frequently to maintain high levels of fertility and prefer to mate with males exhibiting large eyespan, a condition-dependent sexual ornament. If eyespan indicates male reproductive quality, females could directly increase their reproductive success by mating with males with large eyespan. Here we investigate whether male eyespan indicates accessory gland and testis length, and then ask whether mating with large eyespan males affects female fertility. Results Male eyespan was a better predictor of two key male reproductive traits – accessory gland and testis length – than was body size alone. This positive relationship held true over three levels of increasing environmental stress during the maturation of the adult accessory glands and testes. Furthermore, females housed with a large eyespan male exhibited higher levels of fertility than those with small eyespan males. Conclusion Male eyespan in stalk-eyed flies is subject to strong directional mate preference and is a reliable indicator of male reproductive quality – both because males with larger eyespan have bigger accessory glands and testes, and also as they confer higher fertility on females. Fertility enhancement may have arisen because males with larger eyespan mated more often and/or because they transferred more sperm or other substances per ejaculate. The need to ensure high levels of fertility could thus have been an important selective force in the coevolution of female preference and male eyespan in stalk-eyed flies. Our results support the phenotype-linked fertility hypothesis and suggest that it might be of general importance in explaining the evolution of exaggerated male ornaments and displays in species where males only provide females with ejaculates during reproduction. PMID:18710553

Male sexual ornament size is positively associated with reproductive morphology and enhanced fertility in the stalk-eyed fly Teleopsis dalmanni.

PubMed

Rogers, David W; Denniff, Matthew; Chapman, Tracey; Fowler, Kevin; Pomiankowski, Andrew

2008-08-18

Exaggerated male ornaments and displays often evolve in species where males only provide females with ejaculates during reproduction. Although "good genes" arguments are typically invoked to explain this phenomenon, a simpler alternative is possible if variation in male reproductive quality (e.g. sperm number, ejaculate content, mating rate) is an important determinant of female reproductive success. The "phenotype-linked fertility hypothesis" states that female preference for male ornaments or displays has been selected to ensure higher levels of fertility and has driven the evolution of exaggerated male traits. Females of the stalk-eyed fly Teleopsis dalmanni must mate frequently to maintain high levels of fertility and prefer to mate with males exhibiting large eyespan, a condition-dependent sexual ornament. If eyespan indicates male reproductive quality, females could directly increase their reproductive success by mating with males with large eyespan. Here we investigate whether male eyespan indicates accessory gland and testis length, and then ask whether mating with large eyespan males affects female fertility. Male eyespan was a better predictor of two key male reproductive traits--accessory gland and testis length--than was body size alone. This positive relationship held true over three levels of increasing environmental stress during the maturation of the adult accessory glands and testes. Furthermore, females housed with a large eyespan male exhibited higher levels of fertility than those with small eyespan males. Male eyespan in stalk-eyed flies is subject to strong directional mate preference and is a reliable indicator of male reproductive quality--both because males with larger eyespan have bigger accessory glands and testes, and also as they confer higher fertility on females. Fertility enhancement may have arisen because males with larger eyespan mated more often and/or because they transferred more sperm or other substances per ejaculate. The need to ensure high levels of fertility could thus have been an important selective force in the coevolution of female preference and male eyespan in stalk-eyed flies. Our results support the phenotype-linked fertility hypothesis and suggest that it might be of general importance in explaining the evolution of exaggerated male ornaments and displays in species where males only provide females with ejaculates during reproduction.

Male traits, mating tactics and reproductive success in the buff-breasted sandpiper, Tryngites subruficollis

USGS Publications Warehouse

Lanctot, Richard B.; Weatherhead, Patrick J.; Kempenaers, Bart; Scribner, Kim T.

1998-01-01

Buff-breasted sandpipers use a variety of mating tactics to acquire mates, including remaining at a single lek for most of the breeding season, attending multiple leks during the season, displaying solitarily or displaying both on leks and solitarily. We found that differences in body size, body condition, fluctuating asymmetry scores, wing coloration, territory location and behaviour (attraction, solicitation and agonistic) did not explain the observed variation in mating tactics used by males. Which males abandoned versus returned to leks was also not related to morphology or behaviour, and there was no tendency for males to join leks that were larger or smaller than the lek they abandoned. These results suggest that male desertion of leks was not dependent on a male's characteristics nor on the size of the lek he was presently attending. Males did join leks with larger males than their previous lek, perhaps to mate with females attracted to these larger 'hotshot' males. Males at both leks and solitary sites successfully mated. Lek tenure did not affect mating success, although lekking males appeared to mate more frequently than solitary males. Courtship disruption and to a lesser extent, female mimicry, were effective at preventing females from mating at leks, and may offer a partial explanation for female mating off leks. Our analysis that combined all males together within a year (regardless of mating tactic) indicated that males that attended leks for longer periods of time and that had fewer wing spots were significantly more likely to mate. Given some evidence that wing spotting declines with age, and that females inspect male underwings during courtship, the latter result suggests that female choice may play some role in determining male success. We suggest that male buff-breasted sandpipers may use alternative mating tactics more readily than males in other 'classic' lek-breeding species because: (1) unpredictable breeding conditions in this species' high arctic breeding range leads to low lek stability, which in turn hinders mate selection mechanisms mediated by male dominance and female choice; and (2) males are not constrained by morphological markings that indicate status or sex. Both characteristics may reduce the reproductive benefits associated with males adopting one mating tactic and result in a sort of scramble competition in which males switch between tactics as local conditions change.

Fitness of Mass-Reared Males of Anastrepha obliqua (Diptera: Tephritidae) Resulting From Mating Competition Tests in Field Cages.

PubMed

Hernández, Emilio; Liedo, Pablo; Toledo, Jorge; Montoya, Pablo; Perales, Hugo; Ruiz-Montoya, Lorena

2017-12-05

The sterile insect technique uses males that have been mass-reared in a controlled environment. The insects, once released in the field, must compete to mate. However, the mass-rearing condition supposes a loss of fitness that will be noticeable by wild females. To compare the fitness of wild males and mass-reared males, three competition settings were established. In setting 1, wild males, mass-reared males and wild females were released in field cages. In setting 2, wild females and wild males were released without competition, and in setting 3, mass-reared males and mass-reared females were also released without competition. Male fitness was based on their mating success, fecundity, weight and longevity. The fitness of the females was measured based on weight and several demographic parameters. The highest percentage of mating was between wild males and wild females between 0800 and 0900 h in the competition condition, while the mass-reared males started one hour later. The successful wild males weighed more and showed longer mating times, greater longevity and a higher number of matings than the mass-reared males. Although the mass-reared males showed the lowest percentage of matings, their fecundity when mating with wild females indicated a high fitness. Since the survival and fecundity of wild females that mated with mass-reared males decreased to become similar to those of mass-reared females that mated with mass-reared males, females seem to be influenced by the type of male (wild or mass-reared). © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Ovipositional response elicited by normal, irradiated, F$sub 1$ male progeny, or castrated male Trichoplusia ni (Lepidoptera: Noctuidae)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karpenko, C.P.; North, D.T.

1973-11-01

The ovipositional response of untreated Trichoplusia ni (Hubner) females that had mated to unirradiated, irradiated, F/sub 1/ male progeny from irradiated males, or castrated males was studied. Females that mated with irradiated males or F/sub 1/ sons of irradiated males oviposited fewer eggs than females that mated with control males, when all females had received a normal quantity of eupyrene and apyrene sperm. Irradiated males and F/sub 1/ sons of irradiated males that transferred an apparently normal sperm complement elicited significantly better oviposition from untreated females than did treated males that transferred mostly apyrene sperm, apyrene sperm only, or nomore » sperm. Males in the latter categories elicited a better ovipositional response from the untreated females than was observed in virgin females. Normal eupyrene sperm and possibly at least 1 accessory fiuid are required to initiate a completely normal ovipositional response in cabbage looper females. The accessory secretion triggers a significant increase in oviposition, but the greatest increase occurs when males contribute normal amounts of eupyrene sperm. The initiation of oviposition and female receptivity may be closely related in this species. (auth)« less

Gene expression changes in male accessory glands during ageing are accompanied by reproductive decline in Drosophila melanogaster.

PubMed

Koppik, Mareike; Fricke, Claudia

2017-12-01

Senescence is accompanied by loss of reproductive functions. Here, we studied reproductive ageing in Drosophila melanogaster males and asked whether the expected decline in male reproductive success is due to diminished functionality of the male accessory gland (AG). The male AG produces the majority of seminal fluid proteins (SFPs) transferred to the female at mating. SFPs induce female postmating changes and are key to male reproductive success. We measured age-dependent gene expression changes for five representative SFP genes in males from four different age groups ranging from 1 to 6 weeks after eclosion. Simultaneously, we also measured male reproductive success in postmating traits mediated by transfer of these five SFPs. We found a decreased in male SFP gene expression with advancing age and an accompanying decline in male postmating success. Hence, male reproductive senescence is associated with a decline in functionality of the male AG. While overall individual SFP genes decreased in expression, our results point towards the idea that the composition of an ejaculate might change with male age as the rate of change was variable for those five genes. © 2017 John Wiley & Sons Ltd.

Comparison of reproductive traits of regular and irradiated male desert locust Schistocerca gregaria (Orthoptera: Acrididae): Evidence of last-male sperm precedence

PubMed Central

Dushimirimana, Severin; Hance, Thierry; Damiens, David

2012-01-01

Summary The sterile insect technique (SIT) is increasingly used to control pest insect populations. The success of SIT control programs depends on the ability to release sterile males and on the capacity of sterile males to compete with wild males to inseminate wild females. In this study, we evaluated the mating performance of Schistocerca gregaria (Försk.) males irradiated with 4 Gray. We compared reproductive traits, such as duration of precopulation time, mating duration, quantity of sperm stored by females after copulation, number of females mated successively and postmating competition of irradiated males with non-irradiated males. Irradiated males were able to mate but the resulting number of offspring was dramatically reduced compared to the average number of offspring observed during a regular mating. During a single copulation, irradiated males transferred fewer sperm than regular males but, theoretically, this quantity is enough to fertilize all the eggs produced by a female during its reproductive life. Irradiated males also had the ability to remove sperm from a previous mating with unirraditated males. This new information on the mating strategies helps explain the post-copulation guarding behaviour of S. gregaria. PMID:23213413

Sex identification and mating in the blue-ringed octopus, Hapalochlaena lunulata.

PubMed

Cheng; Caldwell

2000-07-01

We studied the reproductive behaviour of the blue-ringed octopus, Hapalochlaena lunulata, in the laboratory by examining 15 male-male and nine male-female interactions. The initiation of physical contact was independent of sex, size or residency status, and there were no noticeable changes in behaviour such as sexual displays associated with courtship or aggression prior to contact. Males did not distinguish between females or other males and copulated (defined as the insertion of the hectocotylus into the mantle cavity of another octopus) readily with both. Spermatophores were released in all copulations with females but not with males. The duration of copulation was significantly longer in male-female interactions (median 160.5 min) than in male-male interactions (median 30 s). Although male-male copulations ended passively with the withdrawal of the hectocotylus by the initiating animal, male-female copulations were always terminated by the females following an intense struggle. These studies suggest the inability of male H. lunulata to determine the sexual identity of potential mates prior to the insertion of the hectocotylus and demonstrate the active role of the female during copulation. Copyright 2000 The Association for the Study of Animal Behaviour.

Sneaker "jack" males outcompete dominant "hooknose" males under sperm competition in Chinook salmon (Oncorhynchus tshawytscha).

PubMed

Young, Brent; Conti, David V; Dean, Matthew D

2013-12-01

In a variety of taxa, males deploy alternative reproductive tactics to secure fertilizations. In many species, small "sneaker" males attempt to steal fertilizations while avoiding encounters with larger, more aggressive, dominant males. Sneaker males usually face a number of disadvantages, including reduced access to females and the higher likelihood that upon ejaculation, their sperm face competition from other males. Nevertheless, sneaker males represent an evolutionarily stable strategy under a wide range of conditions. Game theory suggests that sneaker males compensate for these disadvantages by investing disproportionately in spermatogenesis, by producing more sperm per unit body mass (the "fair raffle") and/or by producing higher quality sperm (the "loaded raffle"). Here, we test these models by competing sperm from sneaker "jack" males against sperm from dominant "hooknose" males in Chinook salmon. Using two complementary approaches, we reject the fair raffle in favor of the loaded raffle and estimate that jack males were ∼1.35 times as likely as hooknose males to fertilize eggs under controlled competitive conditions. Interestingly, the direction and magnitude of this skew in paternity shifted according to individual female egg donors, suggesting cryptic female choice could moderate the outcomes of sperm competition in this externally fertilizing species.

Effect of Mating Status and Age on the Male Mate Choice and Mating Competency in the Common Bed Bug, Cimex lectularius (Hemiptera: Cimicidae).

PubMed

Wang, Desen; Wang, Changlu; Singh, Narinderpal; Cooper, Richard; Zha, Chen; Eiden, Amanda L

2016-04-28

We investigated male mate choice and mating competency in the common bed bug, Cimex lectularius L., using video tracking for 10 min per experiment. In the male mate choice experiment, when a male was placed with two females of different mating status, males preferred to initiate copulation with the virgin female more quickly than with the mated female, and the mean total copulation duration with virgin females (38.0 ± 3.0 s) was significantly longer than with mated females (14.6 ± 3.0 s). When a male was placed with two females of different age, males initiated copulation more quickly with the old virgin female (29-34 d adult emergence) than with the young virgin one (<7 d adult emergence), and the mean total copulation duration with old virgin females (38.4 ± 4.0 s) was significantly longer than with young virgin females (24.0 ± 3.0 s). In the male mating competency experiment where a female was placed with two males of different mating status or age, the virgin males were more eager to mate than the mated males, and the old virgin males (29-34 d adult emergence) were more eager than the young virgin males (<7 d adult emergence), with eagerness measured by the percentage of first mate selected (first copulation occurred) and the total copulation duration by each group of males. Male mating competency is related to postmating duration (PMD); males mated 1 d earlier were significantly less likely to mate than virgin males. However, males mated 7 d earlier showed no significant difference in mating competency compared to virgin males. In conclusion, mate choice in C. lectularius is associated with both male and female mating status, age, and PMD. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Variable assessment of wing colouration in aerial contests of the red-winged damselfly Mnesarete pudica (Zygoptera, Calopterygidae)

NASA Astrophysics Data System (ADS)

Guillermo-Ferreira, Rhainer; Gorb, Stanislav N.; Appel, Esther; Kovalev, Alexander; Bispo, Pitágoras C.

2015-04-01

Wing pigmentation is a trait that predicts the outcome of male contests in some damselflies. Thus, it is reasonable to suppose that males would have the ability to assess wing pigmentation and adjust investment in a fight according to the costs that the rival may potentially impose. Males of the damselfly Mnesarete pudica exhibit red-coloured wings and complex courtship behaviour and engage in striking male-male fights. In this study, we investigated male assessment behaviour during aerial contests. Theory suggests that the relationship between male resource-holding potential (RHP) and contest duration describes the kind of assessment adopted by males: self-assessment, opponent-only assessment or mutual assessment. A recent theory also suggests that weak and strong males exhibit variations in the assessment strategies adopted. We estimated male RHP through male body size and wing colouration (i.e. pigmentation, wing reflectance spectra and transmission spectra) and studied the relationship between male RHP and contest duration from video-documented behavioural observations of naturally occurring individual contests in the field. The results showed that males with more opaque wings and larger red spots were more likely to win contests. The relationships between RHP and contest durations partly supported the self-assessment and the mutual assessment models. We then experimentally augmented the pigmented area of the wings, in order to evaluate whether strong and weak males assess rivals' RHP through wing pigmentation. Our experimental manipulation, however, clearly demonstrated that strong males assess rivals' wing pigmentation. We finally suggest that there is a variation in the assessment strategy adopted by males.

Variable assessment of wing colouration in aerial contests of the red-winged damselfly Mnesarete pudica (Zygoptera, Calopterygidae).

PubMed

Guillermo-Ferreira, Rhainer; Gorb, Stanislav N; Appel, Esther; Kovalev, Alexander; Bispo, Pitágoras C

2015-04-01

Wing pigmentation is a trait that predicts the outcome of male contests in some damselflies. Thus, it is reasonable to suppose that males would have the ability to assess wing pigmentation and adjust investment in a fight according to the costs that the rival may potentially impose. Males of the damselfly Mnesarete pudica exhibit red-coloured wings and complex courtship behaviour and engage in striking male-male fights. In this study, we investigated male assessment behaviour during aerial contests. Theory suggests that the relationship between male resource-holding potential (RHP) and contest duration describes the kind of assessment adopted by males: self-assessment, opponent-only assessment or mutual assessment. A recent theory also suggests that weak and strong males exhibit variations in the assessment strategies adopted. We estimated male RHP through male body size and wing colouration (i.e. pigmentation, wing reflectance spectra and transmission spectra) and studied the relationship between male RHP and contest duration from video-documented behavioural observations of naturally occurring individual contests in the field. The results showed that males with more opaque wings and larger red spots were more likely to win contests. The relationships between RHP and contest durations partly supported the self-assessment and the mutual assessment models. We then experimentally augmented the pigmented area of the wings, in order to evaluate whether strong and weak males assess rivals' RHP through wing pigmentation. Our experimental manipulation, however, clearly demonstrated that strong males assess rivals' wing pigmentation. We finally suggest that there is a variation in the assessment strategy adopted by males.

Visual perceptions of male obesity: a cross-cultural study examining male and female lay perceptions of obesity in Caucasian males.

PubMed

Robinson, Eric; Hogenkamp, Pleunie S

2015-05-16

Obesity is now common and this may have altered visual perceptions of what constitutes a 'normal' and therefore healthy weight. The present study examined cross-cultural differences in male and female participants' ability to visually identify the weight status of photographed Caucasian males. Five hundred and fifty three male and female young adults from the US (high obesity prevalence), UK and Sweden (lower obesity prevalence) participated in an online study. Participants judged the weight status of a series of photographed healthy weight, overweight and obese (class I) Caucasian males and rated the extent to which they believed each male should consider losing weight. There was a strong tendency for both male and female participants to underestimate the weight status of the photographed overweight and obese males. Photographed males were frequently perceived as being of healthier weight than they actually were. Some modest cross-cultural differences were also observed; US participants were worse at recognising obesity than UK participants (p < 0.05) and were also significantly more likely to believe that the photographed obese males did not need to consider losing weight, in comparison to both the UK and Swedish participants (ps < 0.05). No cross-cultural differences were observed for perceptions or attitudes towards the photographed healthy weight or overweight males. The weight status of overweight and obese (class I) Caucasian males is underestimated when judged by males and females using visual information alone. This study provides initial evidence of modest cross-cultural differences in attitudes toward, and the ability to recognise, obesity in Caucasian males.

Suicide Mortality among Kentucky Farmers, 1979-1985.

ERIC Educational Resources Information Center

Stallones, Lorann

1990-01-01

Compared age-specific suicide rates for Kentucky White farmers, Kentucky White males, and United States White males. Found suicide rates highest for farmers, followed by Kentucky males, and the United States males. All males were most likely to use firearms to commit suicide, but farmers and other Kentucky males used firearms significantly more…

Effect of vomeronasal organ removal from male mice on their preference for and neural Fos responses to female urinary odors.

PubMed

Pankevich, Diana E; Cherry, James A; Baum, Michael J

2006-08-01

Four experiments were conducted to determine whether vomeronasal organ (VNO) inputs in male mice mediate the rewarding properties of estrous female urinary odors. Sexually naive male mice with either an intact (VNOi) or lesioned (VNOx) VNO preferred to investigate female urine over water in Y-maze tests. Subsequently, VNOi males ran significantly more quickly and remained in nasal contact longer with estrous female urine than with male urine, whereas VNOx males investigated these odors equally. In home-cage habituation-dishabituation tests, VNOi males also investigated female urine significantly longer than did VNOx males, although both groups investigated female urine longer than other non-body odors. Finally, female urinary odors induced Fos in the nucleus accumbens core of VNOi males but not of VNOx males. Our results suggest that female urinary odors retain some incentive value in VNOx males. However, once direct nasal contact is made with female urine, VNO inputs further activate forebrain mechanisms that amplify the reward salience of this stimulus for the male mouse.

Polygyny, mate-guarding, and posthumous fertilization as alternative male mating strategies.

PubMed

Zamudio, K R; Sinervo, B

2000-12-19

Alternative male mating strategies within populations are thought to be evolutionarily stable because different behaviors allow each male type to successfully gain access to females. Although alternative male strategies are widespread among animals, quantitative evidence for the success of discrete male strategies is available for only a few systems. We use nuclear microsatellites to estimate the paternity rates of three male lizard strategies previously modeled as a rock-paper-scissors game. Each strategy has strengths that allow it to outcompete one morph, and weaknesses that leave it vulnerable to the strategy of another. Blue-throated males mate-guard their females and avoid cuckoldry by yellow-throated "sneaker" males, but mate-guarding is ineffective against aggressive orange-throated neighbors. The ultradominant orange-throated males are highly polygynous and maintain large territories; they overpower blue-throated neighbors and cosire offspring with their females, but are often cuckolded by yellow-throated males. Finally, yellow-throated sneaker males sire offspring via secretive copulations and often share paternity of offspring within a female's clutch. Sneaker males sire more offspring posthumously, indicating that sperm competition may be an important component of their strategy.

Effect of normative masculinity on males' dysfunctional sexual beliefs, sexual attitudes, and perceptions of sexual functioning.

PubMed

Clarke, Michael J; Marks, Anthony D G; Lykins, Amy D

2015-01-01

Male sexual dysfunction is a prevalent and distressing condition, which may be exacerbated by the sufferer's perceptions of masculinity and normative sexual behavior. This study sought to investigate the effect of social context on males' beliefs regarding sexual behavior. The research examined the effect of male role modeling and masculine cues on males' dysfunctional sexual beliefs, sexual attitudes, and self-perceptions of sexual functioning. A sample of 140 male participants, with a mean age of 29 years, was exposed to pictorial and verbal cues that presented different versions of male behavior across three conditions. Results indicated that males exposed to models and cues of traditional masculinity showed significantly increased levels of dysfunctional sexual beliefs and traditional sexual attitudes relative to males exposed to models of modern masculinity. Results also indicated that males exposed to traditional masculine stimuli reported lower levels of sexual inhibition due to fear of performance failure than males exposed to models of modern masculinity. The potential role of social context is discussed in the development and maintenance of male sexual dysfunction and its implications for treatment.

Supplementary feeding affects the breeding behaviour of male European treefrogs (Hyla arborea)

PubMed Central

Meuche, Ivonne; Grafe, T Ulmar

2009-01-01

Background We investigated the effects of energetic constraints on the breeding behaviour of male European treefrogs Hyla arborea and how calling males allocated additional energy supplied by feeding experiments. Results Presence in the chorus was energetically costly indicated by both fed and unfed males losing weight. Males that were supplied with additional energy did not show longer chorus tenure. Instead, fed males returned sooner to the chorus. Additionally, fed males called more often than control males, a novel response for anurans. A significantly higher calling rate was noted from males even 31 nights after supplementary feeding. Conclusion This strategy of allocating additional energy reserves to increasing calling rate is beneficial given the preference of female hylids for males calling at high rates and a female's ability to detect small incremental increases in calling rate. PMID:19128468

Determinants of anger and physical aggression based on sexual orientation: an experimental examination of hypermasculinity and exposure to male gender role violations.

PubMed

Parrott, Dominic J; Zeichner, Amos

2008-12-01

The present study examined the effects of hypermasculinity and exposure to male gender role violations on antigay anger and aggression. Participants were 148 heterosexual men who were randomly assigned to view either a male-male or a male-female erotic video. Participants completed a measure of hypermasculinity and anger was assessed before and after viewing the erotic video. A laboratory paradigm was then used to measure physical aggression toward a gay or heterosexual man. Hypermasculinity predicted greater increases in anger among men who viewed male-male erotica relative to men who viewed male-female erotica. Hypermasculinity also predicted higher levels of physical aggression toward a gay, relative to a heterosexual, man, but only after viewing male-male erotica. Findings were discussed within the context of the General Aggression Model.

Calling behavior of mass-reared and wild Anastrepha serpentina (Diptera: Tephritidae).

PubMed

Castrejón-Gómez, Victor R; Lascares, Shaila; Malo, Edi A; Toledo, Jorge; Rojas, Julio C

2007-08-01

The calling behavior of mass-reared and wild males of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) was studied both in the laboratory and in field cage tests. In the laboratory, density (1, 5, and 10 males per container), age, and hour of day significantly affected calling behavior. Mass-reared males called independently of density, whereas wild males only called at densities of 5 and 10 individuals. Males of both strains started calling when they were 5-7 d old. The daily pattern of male calling was similar in both strains, starting at 0730 hours, and reaching a peak at 1330-1630 hours. Field cage tests showed that mass-reared males started calling when they were 5d old; the period of peak calling was when males were 8-9 d old. In contrast, wild males began calling when they were 10 d old, reaching peaks when males were 13, 15, and 18 d old. Wild males tended to form leks to call during each day of the experiment, whereas mass-reared males only formed leks during 2 d, both strains displaying very low levels. During field cage tests, males, independently of strain, displayed two calling peaks, one peak in the morning and one peak in the afternoon, whereas males observed in the laboratory only showed a single calling peak. The results are discussed in view of the effects of mass rearing A. serpentina males in relation to potential use of the sterile insect technique.

Social recognition is context dependent in single male prairie voles

PubMed Central

Zheng, Da-Jiang; Foley, Lauren; Rehman, Asad; Ophir, Alexander G.

2013-01-01

Single males might benefit from knowing the identity of neighbouring males when establishing and defending boundaries. Similarly, males should discriminate between individual females if this leads to more reproductive opportunities. Contextual social cues may alter the value of learning identity. Knowing the identity of competitors that intrude into an animal’s territory may be more salient than knowing the identity of individuals on whose territory an animal is trespassing. Hence, social and environmental context could affect social recognition in many ways. Here we test social recognition of socially monogamous single male prairie voles, Microtus ochrogaster. In experiment 1 we tested recognition of male or female conspecifics and found that males discriminated between different males but not between different females. In experiment 2 we asked whether recognition of males is influenced when males are tested in their own cage (familiar), in a clean cage (neutral) or in the home cage of another male (unfamiliar). Although focal males discriminated between male conspecifics in all three contexts, individual variation in recognition was lower when males were tested in their home cage (in the presence of familiar social cues) compared to when the context lacked social cues (neutral). Experiment 1 indicates that selective pressures may have operated to enhance male territorial behaviour and indiscriminate mate selection. Experiment 2 suggests that the presence of a conspecific cue heightens social recognition and that home-field advantages might extend to social cognition. Taken together, our results indicate social recognition depends on the social and possibly territorial context. PMID:24273328

Social recognition is context dependent in single male prairie voles.

PubMed

Zheng, Da-Jiang; Foley, Lauren; Rehman, Asad; Ophir, Alexander G

2013-11-01

Single males might benefit from knowing the identity of neighbouring males when establishing and defending boundaries. Similarly, males should discriminate between individual females if this leads to more reproductive opportunities. Contextual social cues may alter the value of learning identity. Knowing the identity of competitors that intrude into an animal's territory may be more salient than knowing the identity of individuals on whose territory an animal is trespassing. Hence, social and environmental context could affect social recognition in many ways. Here we test social recognition of socially monogamous single male prairie voles, Microtus ochrogaster . In experiment 1 we tested recognition of male or female conspecifics and found that males discriminated between different males but not between different females. In experiment 2 we asked whether recognition of males is influenced when males are tested in their own cage (familiar), in a clean cage (neutral) or in the home cage of another male (unfamiliar). Although focal males discriminated between male conspecifics in all three contexts, individual variation in recognition was lower when males were tested in their home cage (in the presence of familiar social cues) compared to when the context lacked social cues (neutral). Experiment 1 indicates that selective pressures may have operated to enhance male territorial behaviour and indiscriminate mate selection. Experiment 2 suggests that the presence of a conspecific cue heightens social recognition and that home-field advantages might extend to social cognition. Taken together, our results indicate social recognition depends on the social and possibly territorial context.

The promoter of an A9 homolog from the conifer Cryptomeria japonica imparts male strobilus-dominant expression in transgenic trees.

PubMed

Kurita, Manabu; Konagaya, Ken-ichi; Watanabe, Atsushi; Kondo, Teiji; Ishii, Katsuaki; Taniguchi, Toru

2013-02-01

KEY MESSAGE : GUS analysis in Cryptomeria japonica revealed that the CjMALE1 promoter is activated in the male strobilus of C. japonica. Toward the development of male sterile technology for Cryptomeria japonica, a male strobilus-dominant promoter of C. japonica was isolated. The CjMALE1 gene was isolated from a male strobilus-specific suppression subtractive hybridization (SSH) library, and the promoter was isolated by the TAIL-PCR method. To characterize the CjMALE1 promoter, β-glucuronidase (GUS)-fused genes were constructed and introduced into C. japonica using Agrobacterium tumefaciens. GUS expression from CjMALE1-2.5 K (2,718 bp fragment)::GUS C. japonica and CjMALE1-1 K (1,029 bp fragment)::GUS C. japonica was detected in the tapetum and microspore mother cells. These promoter fragments were comparably active in the pre-meiotic stage of the male strobilus of C. japonica. Our analysis showed that the 1,029 bp promoter had all the cis-elements necessary for male strobilus-dominant expression of CjMALE1. When CjMALE1-1 K::GUS was introduced into Arabidopsis, GUS expression was detected in the same spatiotemporal pattern as in C. japonica. These results suggest that the CjMALE1 promoter is subject to transcriptional regulatory systems consisting of cis- and trans-elements that have been highly conserved during evolution.

Free-Ranging Male Koalas Use Size-Related Variation in Formant Frequencies to Assess Rival Males

PubMed Central

Charlton, Benjamin D.; Whisson, Desley A.; Reby, David

2013-01-01

Although the use of formant frequencies in nonhuman animal vocal communication systems has received considerable recent interest, only a few studies have examined the importance of these acoustic cues to body size during intra-sexual competition between males. Here we used playback experiments to present free-ranging male koalas with re-synthesised bellow vocalisations in which the formants were shifted to simulate either a large or a small adult male. We found that male looking responses did not differ according to the size variant condition played back. In contrast, male koalas produced longer bellows and spent more time bellowing when they were presented with playbacks simulating larger rivals. In addition, males were significantly slower to respond to this class of playback stimuli than they were to bellows simulating small males. Our results indicate that male koalas invest more effort into their vocal responses when they are presented with bellows that have lower formants indicative of larger rivals, but also show that males are slower to engage in vocal exchanges with larger males that represent more dangerous rivals. By demonstrating that male koalas use formants to assess rivals during the breeding season we have provided evidence that male-male competition constitutes an important selection pressure for broadcasting and attending to size-related formant information in this species. Further empirical studies should investigate the extent to which the use of formants during intra-sexual competition is widespread throughout mammals. PMID:23922967

Slow stamen movement in a perennial herb decreases male-male and male-female interference.

PubMed

Wang, Lingyan; Bao, Yu; Wang, Hanxi; He, Chunguang; Wang, Ping; Sheng, Lianxi; Tang, Zhanhui

2017-07-01

Approximately 80 % of angiosperm species produce hermaphroditic flowers, which face the problem of male - male sexual interference (one or more anthers gets in the way of disseminating pollen from other anthers) or male - female sexual interference (the pistil interferes with disseminating pollen from the anthers by preventing the anther from touching a pollinator, or the anther prevents pollinator from depositing outcross pollen on the stigma). Slow stamen movement in hermaphrodite flowers has been interpreted as an adaptation for reducing male - male sexual interference. Using slow stamen movement in Lychnis cognata (Caryophyllaceae), this study presents new evidence that this phenomenon can reduce both male - male and male - female sexual interference. Ten stamens in L. cognata flowers vertically elongated their filaments in two batches and displayed similar patterns in pollen dispensing. More importantly, 10 stamens bend out of the floral centre by curving the filament also in 2 batches and pollen grains located at the flower centre displayed the highest viability. Thus, three stages of stamen movement can be identified, comprising two male stages (M1 and M2) and one female stage (F). We found that the main pollinator for L. cognata, Bhutanitis yulongensis (Papilionodae) generally preferred M1 flowers. Manipulation experiments show that vertical stamen movement enabled the anthers to dehisce at different times to prolong the presentation of pollen grains. Horizontal movement of the stamen decreased both male - male and male - female interference. However, vertical stamen movement had a minor role in increasing amount of pollen received by the stigma. This study provides the first direct experimental evidence of concurrent male - male and male - female interference in a flower. We suggest that the selection pressure to reduce such interference might be a strong force in floral evolution. We also propose that other selective pressure, including pollen dispensing mechanisms, pollen longevity, pollinator behaviour and weather, might contribute to floral evolution.

Infant Mortality Risk and Paternity Certainty Are Associated with Postnatal Maternal Behavior toward Adult Male Mountain Gorillas (Gorilla beringei beringei)

PubMed Central

Rosenbaum, Stacy; Hirwa, Jean Paul; Silk, Joan B.; Vigilant, Linda; Stoinski, Tara S.

2016-01-01

Sexually selected infanticide is an important source of infant mortality in many mammalian species. In species with long-term male-female associations, females may benefit from male protection against infanticidal outsiders. We tested whether mountain gorilla (Gorilla beringei beringei) mothers in single and multi-male groups monitored by the Dian Fossey Gorilla Fund’s Karisoke Research Center actively facilitated interactions between their infants and a potentially protective male. We also evaluated the criteria mothers in multi-male groups used to choose a preferred male social partner. In single male groups, where infanticide risk and paternity certainty are high, females with infants <1 year old spent more time near and affiliated more with males than females without young infants. In multi-male groups, where infanticide rates and paternity certainty are lower, mothers with new infants exhibited few behavioral changes toward males. The sole notable change was that females with young infants proportionally increased their time near males they previously spent little time near when compared to males they had previously preferred, perhaps to encourage paternity uncertainty and deter aggression. Rank was a much better predictor of females’ social partner choice than paternity. Older infants (2–3 years) in multi-male groups mirrored their mothers’ preferences for individual male social partners; 89% spent the most time in close proximity to the male their mother had spent the most time near when they were <1 year old. Observed discrepancies between female behavior in single and multi-male groups likely reflect different levels of postpartum intersexual conflict; in groups where paternity certainty and infanticide risk are both high, male-female interests align and females behave accordingly. This highlights the importance of considering individual and group-level variation when evaluating intersexual conflict across the reproductive cycle. PMID:26863300

Turn it off! the effects of exposure to male-male erotic imagery on heterosexuals' attitudes toward gay men.

PubMed

Golom, Frank D; Mohr, Jonathan J

2011-01-01

Despite the recent proliferation of lesbian, gay, and bisexual (LGB) thematic content in U.S. media, there have been relatively few empirical investigations examining its impact on heterosexuals' attitudes toward LGB individuals. This study examined the effect of one type of content, male-male homoerotic imagery, on male and female heterosexuals' attitudes toward, stereotypes about, and affective reactions to gay men. One hundred ninety-eight undergraduate students were assigned to either a male-male or male-female erotica condition, and their corresponding attitudes toward gay men were assessed. Results revealed that the effect of erotic imagery (male-male vs. male-female) on participants' stereotype and affect scores differed for men and women at varying levels of sexual anxiety. The implications of these findings are discussed in light of the literature on exposure to erotic imagery and attitudes toward gay men. In particular, the study highlights the need for additional research that acknowledges within-gender heterogeneity with respect to antigay attitude valence, extremity, and function.

Mating and male pheromone kill Caenorhabditis males through distinct mechanisms

PubMed Central

Shi, Cheng; Runnels, Alexi M; Murphy, Coleen T

2017-01-01

Differences in longevity between sexes is a mysterious yet general phenomenon across great evolutionary distances. To test the roles of responses to environmental cues and sexual behaviors in longevity regulation, we examined Caenorhabditis male lifespan under solitary, grouped, and mated conditions. We find that neurons and the germline are required for male pheromone-dependent male death. Hermaphrodites with a masculinized nervous system secrete male pheromone and are susceptible to male pheromone killing. Male pheromone-mediated killing is unique to androdioecious Caenorhabditis, and may reduce the number of males in hermaphroditic populations; neither males nor females of gonochoristic species are susceptible to male pheromone killing. By contrast, mating-induced death, which is characterized by germline-dependent shrinking, glycogen loss, and ectopic vitellogenin expression, utilizes distinct molecular pathways and is shared between the sexes and across species. The study of sex- and species-specific regulation of aging reveals deeply conserved mechanisms of longevity and population structure regulation. DOI: http://dx.doi.org/10.7554/eLife.23493.001 PMID:28290982

Mating success of males with and without wing patch in Drosophila biarmipes.

PubMed

Hegde, S N; Chethan, B K; Krishna, M S

2005-10-01

Some males of D. biarmipes--synonym of D. rajasekari and D. raychaudhuri have a black patch on the wing. The patch extends from the apical margin of wing to the third longitudinal vein. Field and laboratory studies have been carried out in D. biarmipes to study role of male's wing patch in mating success. The field study shows that nature favors D. biarmipes males with patch. Although males without patch mated, males with patch have higher mating success suggesting the role of wing patch during courtship. Further, among mating males, males with patch had longer wings than males without patch. During courtship, males with patch oriented and mated faster; performed courtship acts such as tapping, scissoring, vibration, licking and twist dance more times than males without patch in both competitive and non-competitive situations. The results indicate that there is a casual relationship between the presence of wing patch, mating speed and success. Also there is a correlation between presence of wing patch, size of the flies and mating success.

Testosterone, Plumage Colouration and Extra-Pair Paternity in Male North-American Barn Swallows

PubMed Central

Eikenaar, Cas; Whitham, Megan; Komdeur, Jan; van der Velde, Marco; Moore, Ignacio T.

2011-01-01

In most monogamous bird species, circulating testosterone concentration in males is elevated around the social female's fertile period. Variation in elevated testosterone concentrations among males may have a considerable impact on fitness. For example, testosterone implants enhance behaviours important for social and extra-pair mate choice. However, little is known about the relationship between natural male testosterone concentration and sexual selection. To investigate this relationship we measured testosterone concentration and sexual signals (ventral plumage colour and tail length), and determined within and extra-pair fertilization success in male North American barn swallows (Hirundo rustica erythrogaster). Dark rusty coloured males had higher testosterone concentrations than drab males. Extra-pair paternity was common (42% and 31% of young in 2009 and 2010, respectively), but neither within- nor extra-pair fertilization success was related to male testosterone concentration. Dark rusty males were less often cuckolded, but did not have higher extra-pair or total fertilization success than drab males. Tail length did not affect within- or extra-pair fertilization success. Our findings suggest that, in North American barn swallows, male testosterone concentration does not play a significant direct role in female mate choice and sexual selection. Possibly plumage colour co-varies with a male behavioural trait, such as aggressiveness, that reduces the chance of cuckoldry. This could also explain why dark males have higher testosterone concentrations than drab males. PMID:21853105

An integral projection model with YY-males and application to evaluating grass carp control

USGS Publications Warehouse

Erickson, Richard A.; Eager, Eric A.; Brey, Marybeth; Hansen, Michael J.; Kocovsky, Patrick

2017-01-01

Invasive fish species disrupt ecosystems and cause economic damage. Several methods have been discussed to control populations of invasive fish including the release of YY-males. YY-males are fish that have 2 male chromosomes compared to a XY-male. When YY-males mate, they only produce male (XY) offspring. This decreases the female proportion of the population and can, in theory, eradicate local populations by biasing the sex-ratio. YY-males have been used as a population control tool for brook trout in montane streams and lakes in Idaho, USA. The YY-male control method has been discussed for grass carp in Lake Erie, North America. We developed and presented an integral projection model for grass carp to model the use of YY-males as a control method for populations in this lake. Using only the YY-male control method, we found that high levels of YY-males would need to be release annually to control the species. Specifically, these levels were the same order of magnitude as the baseline adult population (e.g., 1000 YY-males needed to be released annual for 20 years to control a baseline adult population of 2500 grass carp). These levels may not be reasonable or obtainable for fisheries managers given the impacts of YY-males on aquatic vegetation and other constraints of natural resource management.

The contrasting role of male relatedness in different mechanisms of sexual selection in red junglefowl.

PubMed

Tan, Cedric Kai Wei; Doyle, Philippa; Bagshaw, Emma; Richardson, David S; Wigby, Stuart; Pizzari, Tommaso

2017-02-01

In structured populations, competition for reproductive opportunities should be relaxed among related males. The few tests of this prediction often neglect the fact that sexual selection acts through multiple mechanisms, both before and after mating. We performed experiments to study the role of within-group male relatedness across pre- and postcopulatory mechanisms of sexual selection in social groups of red junglefowl, Gallus gallus, in which two related males and one unrelated male competed over females unrelated to all the males. We confirm theoretical expectations that, after controlling for male social status, competition over mating was reduced among related males. However, this effect was contrasted by other sexual selection mechanisms. First, females biased male mating in favor of the unrelated male, and might also favor his inseminations after mating. Second, males invested more-rather than fewer-sperm in postcopulatory competition with relatives. A number of factors may contribute to explain this counterintuitive pattern of sperm allocation, including trade-offs between male investment in pre- versus postcopulatory competition, differences in the relative relatedness of pre- versus postcopulatory competitors, and female bias in sperm utilization in response to male relatedness. Collectively, these results reveal that within-group male relatedness may have contrasting effects in different mechanisms of sexual selection. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Scent marking in a territorial African antelope: I. The maintenance of borders between male oribi.

PubMed

Brashares; Arcese

1999-01-01

Scent marking is ubiquitous among the dwarf antelope and gazelles of Africa, but its function has been the subject of debate. This study examined preorbital gland scent marking in the oribi, Ourebia ourebi, a territorial African antelope. Several hypotheses for the function of scent marking by territorial antelope were tested with observational data. Of these, the hypotheses that scent marking is driven by intrasexual competition between neighbouring males, and that marks serve as an honest advertisement of a male's ability to defend his territory from rivals, were supported best. Thirty-three territorial male oribi on 23 territories marked most at borders shared with other territorial males, and territorial males marked more often at borders shared with multimale groups than at borders shared with a single male. This suggests that males perceived neighbouring male groups as a greater threat to territory ownership than neighbouring males that defended their territories without the aid of adult subordinates. Marking rate was unrelated to territory size or the number of females on adjacent territories, but males with many male neighbours marked at higher rates than those with fewer male neighbours. These results suggest that the presence of male neighbours has a greater effect on the scent marking behaviour of territorial antelope than has been considered previously. Copyright 1999 The Association for the Study of Animal Behaviour.

Suicide mortality of young, middle-aged and elderly males and females in Japan for the years 1953-96: time series analysis for the effects of unemployment, female labour force, young and aged population, primary industry and population density.

PubMed

Yamasaki, Akiko; Araki, Shunichi; Sakai, Ryoji; Yokoyama, Kazuhito; Voorhees, A Scott

2008-12-01

Effects of nine social life indicators on age-adjusted and age-specific annual suicide mortality of male and female Japanese population in the years 1953-96 were investigated by multiple regression analysis on time series data. Unemployment rate was significantly related to the age-adjusted mortality in both males and females. Also, female labour force participation was positively related to the male mortality; persons and 65 and above was inversely related to the male mortality. Results on the age-specific mortality indicated that: during the 44 yr, (1) unemployment significantly related with the mortality of young, middle-aged and elderly males and young females; (2) female labour force participation significantly related with the mortality of young and elderly males and young females; aged population significantly related with the mortality of middle-aged and elderly males; (4) young population significantly related with the mortality of young and middle-aged males and females; (5) divorce significantly related with the mortality of middle-aged and elderly males and young males and females; (6) persons employed in primary industries significantly related with the mortality in middle-aged males and young males and females; and (7) population density significantly related with the mortality of middle-aged males and young females.

Rival male chemical cues evoke changes in male pre- and post-copulatory investment in a flour beetle

PubMed Central

Lane, Sarah M.; Solino, Joanna H.; Mitchell, Christopher; Blount, Jonathan D.; Okada, Kensuke; Hunt, John

2015-01-01

Males can gather information on the risk and intensity of sperm competition from their social environment. Recent studies have implicated chemosensory cues, for instance cuticular hydrocarbons (CHCs) in insects, as a key source of this information. Here, using the broad-horned flour beetle (Gnatocerus cornutus), we investigated the importance of contact-derived rival male CHCs in informing male perception of sperm competition risk and intensity. We experimentally perfumed virgin females with male CHCs via direct intersexual contact and measured male pre- and post-copulatory investment in response to this manipulation. Using chemical analysis, we verified that this treatment engendered changes to perfumed female CHC profiles, but did not make perfumed females “smell” mated. Despite this, males responded to these chemical changes. Males increased courtship effort under low levels of perceived competition (from 1–3 rivals), but significantly decreased courtship effort as perceived competition rose (from 3–5 rivals). Furthermore, our measurement of ejaculate investment showed that males allocated significantly more sperm to perfumed females than to control females. Together, these results suggest that changes in female chemical profile elicited by contact with rival males do not provide males with information on female mating status, but rather inform males of the presence of rivals within the population and thus provide a means for males to indirectly assess the risk of sperm competition. PMID:26167098

Sperm competition generates evolution of increased paternal investment in a sex role-reversed seed beetle.

PubMed

Booksmythe, I; Fritzsche, K; Arnqvist, G

2014-12-01

When males provide females with resources at mating, they can become the limiting sex in reproduction, in extreme cases leading to the reversal of typical courtship roles. The evolution of male provisioning is thought to be driven by male reproductive competition and selection for female fecundity enhancement. We used experimental evolution under male- or female-biased sex ratios and limited or unlimited food regimes to investigate the relative roles of these routes to male provisioning in a sex role-reversed beetle, Megabruchidius tonkineus, where males provide females with nutritious ejaculates. Males evolving under male-biased sex ratios transferred larger ejaculates than did males from female-biased populations, demonstrating a sizeable role for reproductive competition in the evolution of male provisioning. Although larger ejaculates elevated female lifetime offspring production, we found little evidence of selection for larger ejaculates via fecundity enhancement: males evolving under resource-limited and unlimited conditions did not differ in mean ejaculate size. Resource limitation did, however, affect the evolution of conditional ejaculate allocation. Our results suggest that the resource provisioning that underpins sex role reversal in this system is the result of male-male reproductive competition rather than of direct selection for males to enhance female fecundity. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Corticosteroid receptor expression in a teleost fish that displays alternative male reproductive tactics.

PubMed

Arterbery, Adam S; Deitcher, David L; Bass, Andrew H

2010-01-01

Corticosteroid signaling mechanisms mediate a wide range of adaptive physiological responses, including those essential to reproduction. Here, we investigated the presence and relative abundance of corticosteroid receptors during the breeding season in the plainfin midshipman fish (Porichthys notatus), a species that has two male reproductive morphs. Only type I "singing" males acoustically court females and aggressively defend a nest site, whereas type II "sneaker" males steal fertilizations from nesting type I males. Cloning and sequencing first identified glucocorticoid (GR) and mineralocorticoid (MR) receptors in midshipman that exhibited high sequence identity with other vertebrate GRs and MRs. Absolute-quantitative real-time PCR then revealed higher levels of GR in the central nervous system (CNS) of type II males than type I males and females, while GR levels in the sound-producing, vocal muscle and the liver were higher in type I males than type II males and females. MR expression was also greater in the CNS of type II males than type I males or females, but the differences were more modest in magnitude. Lastly, plasma levels of cortisol, the main glucocorticoid in teleosts, were 2- to 3-fold greater in type II males compared to type I males. Together, the results suggest a link between corticosteroid regulation and physiological and behavioral variation in a teleost fish that displays male alternative reproductive tactics.

Tactic changes in dusky frillgoby Bathygobius fuscus sneaker males: effects of body size and nest availability.

PubMed

Takegaki, T; Kaneko, T; Matsumoto, Y

2013-02-01

Field and laboratory studies were conducted to examine the effects of nest availability and body size on changes in male mating tactics from sneaking to nest-holding in the dusky frillgoby Bathygobius fuscus. In the field, the body size of nest-holding males decreased from early to mid-breeding season, suggesting the possibility of a change in the tactics of sneaker males to nest-holding. Many sneaker males did not use vacant spawning nests even when size-matched nests were available, but they continued to reproduce as sneakers. Similarly, in aquarium experiments with available vacant nests, some sneaker males became nest-holders irrespective of their body size, but some did not. These results showed that nest availability is not a limiting factor for changes in tactics by sneaker males in this species. Because tactic-unchanged sneaker males were co-housed with larger nest-holding males in the tanks, the body size of nearby nest-holding males may have affected the decision to change tactics for sneaker males. Moreover, smaller individuals among tactic-changed males tended to spend more time until spawning, probably because they had relatively larger costs and smaller benefits of reproduction as nest-holding males compared to larger males. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Age-Related Changes in Children's Hedonic Response to Male Body Odor.

ERIC Educational Resources Information Center

Stevenson, Richard J.; Repacholi, Betty M.

2003-01-01

Examined children's and adolescents' ability to identify male sweat and other odors and their rating of odors for liking. Found that only female adolescents could identify and disliked male sweat. When cued about odor identity, both male and female adolescents disliked male sweat more than children. Concluded that dislike for male sweat odor may…

Is courtship intensity a signal of male parental care in Red-winged Blackbirds (Agelaius phoeniceus)?

USGS Publications Warehouse

Yasukawa, Ken; Knight, Richard L.; Skagen, Susan Knight

1987-01-01

We studied Red-winged Blackbird (Agelaius phoeniceus) behavior in marsh and prairie habitats to determine whether courting males provide cues of their nest defense, whether females prefer males that defend nests vigorously, and whether male nest defense affects nest success. We found no evidence that courtship behavior provides cues of male nest defense, or that females prefer males that court intensely. We found evidence that females nesting in marshes prefer males that defend nests intensely, but no evidence that intensely defending males in the prairie habitat achieve high nest success. We found differences, however, between marsh and prairie habitats that suggest a coarse-grained relationship between male parental quality and female choice of mate in this species.

When the ball is in the female's court: How the scramble-competition mating system of the North American red squirrel has shaped male physiology and testosterone dynamics.

PubMed

Boonstra, Rudy; Dušek, Adam; Lane, Jeffrey E; Boutin, Stan

2017-10-01

Male reproductive success in most mammals is determined by their success in direct inter-male competition through aggression and conflict, resulting in female-defense mating systems being predominant. This is linked to male testosterone levels and its dynamics. However, in certain environments, a scramble-competition mating system has evolved, where female reproductive behavior takes precedence and male testosterone dynamics are unlikely to be related to inter-male competition. We studied the North American red squirrel (Tamiasciurus hudsonicus), a species with a well-established scramble-competition system. Using an ACTH hormonal challenge protocol as a proxy for competitive interactions, we compared the testosterone dynamics in breeding males in late winter with that in nonbreeding males in late spring in the Yukon. To gain an integrated picture of their physiological state, we also assessed changes in their stress response, body mass, energy mobilization, and indices of immune function. Testosterone levels at the base bleed were high in breeding males (2.72ng/mL) and virtually absent in non-breeding males (0.04ng/mL). Breeding males were in better condition (heavier body mass, higher hematocrit, and higher erythrocytes), had higher indices of immune function (neutrophil:lymphocyte ratio), but a similar ability to mobilize energy (glucose) compared with non-breeding males. Though total cortisol was higher in non-breeding males, free cortisol was twice as high in breeding males as their corticosteroid binding globulin levels were half as high. In response to the ACTH challenge, testosterone levels in breeding males declined 49% over the first hour and increased 36% over the next hour; in non-breeding males levels showed no change. Free cortisol increased only modestly (26% in breeding males; 23% in non-breeding males). Glucose levels changed similarly in breeding and nonbreeding males, declining for the first 30min and then increasing for the next 60min. Thus, testosterone and components of the stress axis function in a profoundly different manner in male red squirrels than in males of mammals with female-defense mating systems. There are four probable interrelated reasons for these adaptations in male red squirrels: the marginal benefits of each mating, the constraints of mate searching away from their own resource-based territories, energy mobilization in a harsh environment, and a long life span. Copyright © 2017 Elsevier Inc. All rights reserved.

Could Circumcision of HIV-Positive Males Benefit Voluntary Medical Male Circumcision Programs in Africa? Mathematical Modeling Analysis

PubMed Central

Awad, Susanne F.; Sgaier, Sema K.; Lau, Fiona K.; Mohamoud, Yousra A.; Tambatamba, Bushimbwa C.; Kripke, Katharine E.; Thomas, Anne G.; Bock, Naomi; Reed, Jason B.; Njeuhmeli, Emmanuel; Abu-Raddad, Laith J.

2017-01-01

Background The epidemiological and programmatic implications of inclusivity of HIV-positive males in voluntary medical male circumcision (VMMC) programs are uncertain. We modeled these implications using Zambia as an illustrative example. Methods and Findings We used the Age-Structured Mathematical (ASM) model to evaluate, over an intermediate horizon (2010–2025), the effectiveness (number of VMMCs needed to avert one HIV infection) of VMMC scale-up scenarios with varying proportions of HIV-positive males. The model was calibrated by fitting to HIV prevalence time trend data from 1990 to 2014. We assumed that inclusivity of HIV positive males may benefit VMMC programs by increasing VMMC uptake among higher risk males, or by circumcision reducing HIV male-to-female transmission risk. All analyses were generated assuming no further antiretroviral therapy (ART) scale-up. The number of VMMCs needed to avert one HIV infection was projected to increase from 12.2 VMMCs per HIV infection averted, in a program that circumcises only HIV-negative males, to 14.0, in a program that includes HIV-positive males. The proportion of HIV-positive males was based on their representation in the population (e.g. 12.6% of those circumcised in 2010 would be HIV-positive based on HIV prevalence among males of 12.6% in 2010). However, if a program that only reaches out to HIV-negative males is associated with 20% lower uptake among higher-risk males, the effectiveness would be 13.2 VMMCs per infection averted. If improved inclusivity of HIV-positive males is associated with 20% higher uptake among higher-risk males, the effectiveness would be 12.4. As the assumed VMMC efficacy against male-to-female HIV transmission was increased from 0% to 20% and 46%, the effectiveness of circumcising regardless of HIV status improved from 14.0 to 11.5 and 9.1, respectively. The reduction in the HIV incidence rate among females increased accordingly, from 24.7% to 34.8% and 50.4%, respectively. Conclusion Improving inclusivity of males in VMMC programs regardless of HIV status increases VMMC effectiveness, if there is moderate increase in VMMC uptake among higher-risk males and/or if there is moderate efficacy for VMMC against male-to-female transmission. In these circumstances, VMMC programs can reduce the HIV incidence rate in males by nearly as much as expected by some ART programs, and additionally, females can benefit from the intervention nearly as much as males. PMID:28118387

Could Circumcision of HIV-Positive Males Benefit Voluntary Medical Male Circumcision Programs in Africa? Mathematical Modeling Analysis.

PubMed

Awad, Susanne F; Sgaier, Sema K; Lau, Fiona K; Mohamoud, Yousra A; Tambatamba, Bushimbwa C; Kripke, Katharine E; Thomas, Anne G; Bock, Naomi; Reed, Jason B; Njeuhmeli, Emmanuel; Abu-Raddad, Laith J

2017-01-01

The epidemiological and programmatic implications of inclusivity of HIV-positive males in voluntary medical male circumcision (VMMC) programs are uncertain. We modeled these implications using Zambia as an illustrative example. We used the Age-Structured Mathematical (ASM) model to evaluate, over an intermediate horizon (2010-2025), the effectiveness (number of VMMCs needed to avert one HIV infection) of VMMC scale-up scenarios with varying proportions of HIV-positive males. The model was calibrated by fitting to HIV prevalence time trend data from 1990 to 2014. We assumed that inclusivity of HIV positive males may benefit VMMC programs by increasing VMMC uptake among higher risk males, or by circumcision reducing HIV male-to-female transmission risk. All analyses were generated assuming no further antiretroviral therapy (ART) scale-up. The number of VMMCs needed to avert one HIV infection was projected to increase from 12.2 VMMCs per HIV infection averted, in a program that circumcises only HIV-negative males, to 14.0, in a program that includes HIV-positive males. The proportion of HIV-positive males was based on their representation in the population (e.g. 12.6% of those circumcised in 2010 would be HIV-positive based on HIV prevalence among males of 12.6% in 2010). However, if a program that only reaches out to HIV-negative males is associated with 20% lower uptake among higher-risk males, the effectiveness would be 13.2 VMMCs per infection averted. If improved inclusivity of HIV-positive males is associated with 20% higher uptake among higher-risk males, the effectiveness would be 12.4. As the assumed VMMC efficacy against male-to-female HIV transmission was increased from 0% to 20% and 46%, the effectiveness of circumcising regardless of HIV status improved from 14.0 to 11.5 and 9.1, respectively. The reduction in the HIV incidence rate among females increased accordingly, from 24.7% to 34.8% and 50.4%, respectively. Improving inclusivity of males in VMMC programs regardless of HIV status increases VMMC effectiveness, if there is moderate increase in VMMC uptake among higher-risk males and/or if there is moderate efficacy for VMMC against male-to-female transmission. In these circumstances, VMMC programs can reduce the HIV incidence rate in males by nearly as much as expected by some ART programs, and additionally, females can benefit from the intervention nearly as much as males.

Evolution of mate-harm, longevity and behaviour in male fruit flies subjected to different levels of interlocus conflict.

PubMed

Nandy, Bodhisatta; Gupta, Vanika; Sen, Sharmi; Udaykumar, Niveda; Samant, Manas Arun; Ali, Syed Zeeshan; Prasad, Nagaraj Guru

2013-09-28

Interlocus conflict predicts (a) evolution of traits, beneficial to males but detrimental to females and (b) evolution of aging and life-span under the influence of the cost of bearing these traits. However, there are very few empirical investigations shedding light on these predictions. Those that do address these issues, mostly reported response of male reproductive traits or the lack of it and do not address the life-history consequence of such evolution. Here, we test both the above mentioned predictions using experimental evolution on replicate populations of Drosophila melanogaster. We present responses observed after >45 generations of altered levels of interlocus conflict (generated by varying the operational sex ratio). Males from the male biased (high conflict, M-regime) regime evolved higher spontaneous locomotor activity and courtship frequency. Females exposed to these males were found to have higher mortality rate. Males from the female biased regime (low conflict, F-regime) did not evolve altered courtship frequency and activity. However, progeny production of females continuously exposed to F-males was significantly higher than the progeny production of females exposed to M-males indicating that the F-males are relatively benign towards their mates. We found that males from male biased regime lived shorter compared to males from the female biased regime. F-males (evolving under lower levels of sexual conflict) evolved decreased mate harming ability indicating the cost of maintenance of the suit of traits that cause mate-harm. The M-males (evolving under higher levels sexual conflict) caused higher female mortality indicating that they had evolved increased mate harming ability, possibly as a by product of increased reproduction related activity. There was a correlated evolution of life-history of the M and F-males. M-regime males lived shorter compared to the males from F-regime, possibly due to the cost of investing more in reproductive traits. In combination, these results suggest that male reproductive traits and life-history traits can evolve in response to the altered levels of interlocus sexual conflict.

Comparison of male conflict behavior in chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), with specific regard to coalition and post-conflict behavior.

PubMed

Surbeck, Martin; Boesch, Christophe; Girard-Buttoz, Cédric; Crockford, Catherine; Hohmann, Gottfried; Wittig, Roman M

2017-06-01

Coalitions among males during within group conflicts have a strong influence on the competitive and social environment within social groups. To evaluate possible variation in the occurrence of such coalitions in our closest relatives, chimpanzees and bonobos, we compared male aggression and coalitionary behavior in two natural communities, one of each species, with a similar size and composition. Furthermore we compared affiliative behavior that might be related to coalition formation among males. We found higher frequencies of aggression and a greater likelihood to form coalitions during within-group conflicts among wild male chimpanzees at Taï compared to wild male bonobos at LuiKotale. The species differed in the predominant sex of the male coalition partners, with male bonobos forming coalitions more often with females, while male chimpanzees formed coalitions more often with other males. Compared to male bonobos, male chimpanzees showed higher rates of grooming and tended to reconcile more conflicts with other males. Overall our results showed lower frequencies of reconciliation among bonobos than those described in captivity and at artificial feeding sites. These findings add to the evidence that male cooperation and conflict resolution are potentially very different in bonobos and chimpanzees, despite the fact that these two species are closely related, live in multi-male, multi-female communities with a high degree of fission-fusion dynamics and have female-biased migration patterns. Given the correlation between aggressive, cooperative and some affiliative patterns within the species in our study, we hypothesize that the fitness benefits of male relationships are greater in chimpanzees compared to bonobos. © 2017 Wiley Periodicals, Inc.

Preference for Male Traits Differ in Two Female Morphs of the Tree Lizard, Urosaurus ornatus

PubMed Central

Lattanzio, Matthew S.; Metro, Kevin J.; Miles, Donald B.

2014-01-01

Non-random female mating preferences may contribute to the maintenance of phenotypic variation in color polymorphic species. However, the effect of female preference depends on the types of male traits used as signals by receptive females. If preference signals derive from discrete male traits (i.e., morph-specific), female preferences may rapidly fix to a morph. However, female preference signals may also include condition-dependent male traits. In this scenario, female preference may differ depending on the social context (i.e., male morph availability). Male tree lizards (Urosaurus ornatus) exhibit a dewlap color polymorphism that covaries with mating behavior. Blue morph males are aggressive and defend territories, yellow males are less aggressive and defend smaller territories, and orange males are typically nomadic. Female U. ornatus are also polymorphic in dewlap color, but the covariation between dewlap color and female behavior is unknown. We performed an experiment to determine how female mate choice depends on the visual and chemical signals produced by males. We also tested whether female morphs differ in their preferences for these signals. Female preferences involved both male dewlap color and size of the ventral color patch. However, the female morphs responded to these signals differently and depended on the choice between the types of male morphs. Our experiment revealed that females may be capable of distinguishing among the male morphs using chemical signals alone. Yellow females exhibit preferences based on both chemical and visual signals, which may be a strategy to avoid ultra-dominant males. In contrast, orange females may prefer dominant males. We conclude that female U. ornatus morphs differ in mating behavior. Our findings also provide evidence for a chemical polymorphism among male lizards in femoral pore secretions. PMID:25033282

Female Choice or Male Sex Drive? The Advantages of Male Body Size during Mating in Drosophila Melanogaster.

PubMed

Jagadeeshan, Santosh; Shah, Ushma; Chakrabarti, Debarti; Singh, Rama S

2015-01-01

The mating success of larger male Drosophila melanogaster in the laboratory and the wild has been traditionally been explained by female choice, even though the reasons are generally hard to reconcile. Female choice can explain this success by virtue of females taking less time to mate with preferred males, but so can the more aggressive or persistent courtships efforts of large males. Since mating is a negotiation between the two sexes, the behaviors of both are likely to interact and influence mating outcomes. Using a series of assays, we explored these negotiations by testing for the relative influence of male behaviors and its effect on influencing female courtship arousal threshold, which is the time taken for females to accept copulation. Our results show that large males indeed have higher copulation success compared to smaller males. Competition between two males or an increasing number of males had no influence on female sexual arousal threshold;-females therefore may have a relatively fixed 'arousal threshold' that must be reached before they are ready to mate, and larger males appear to be able to manipulate this threshold sooner. On the other hand, the females' physiological and behavioral state drastically influences mating; once females have crossed the courtship arousal threshold they take less time to mate and mate indiscriminately with large and small males. Mating quicker with larger males may be misconstrued to be due to female choice; our results suggest that the mating advantage of larger males may be more a result of heightened male activity and relatively less of female choice. Body size per se may not be a trait under selection by female choice, but size likely amplifies male activity and signal outputs in courtship, allowing them to influence female arousal threshold faster.

Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination.

PubMed

Pavlova, Viola; Nabe-Nielsen, Jacob; Dietz, Rune; Sonne, Christian; Grimm, Volker

2016-11-30

Polar bears (Ursus maritimus) from East Greenland and Svalbard exhibited very high concentrations of polychlorinated biphenyls (PCBs) in the 1980s and 1990s. In Svalbard, slow population growth during that period was suspected to be linked to PCB contamination. In this case study, we explored how PCBs could have impacted polar bear population growth and/or male reproductive success in Svalbard during the mid-1990s by reducing the fertility of contaminated males. A dose-response relationship linking the effects of PCBs to male polar bear fertility was extrapolated from studies of the effects of PCBs on sperm quality in rodents. Based on this relationship, an individual-based model of bear interactions during the breeding season predicted fertilization success under alternative assumptions regarding male-male competition for females. Contamination reduced pregnancy rates by decreasing the availability of fertile males, thus triggering a mate-finding Allee effect, particularly when male-male competition for females was limited or when infertile males were able to compete with fertile males for females. Comparisons of our model predictions on age-dependent reproductive success of males with published empirical observations revealed that the low representation of 10-14-year-old males among breeding males documented in Svalbard in mid-1990s could have resulted from PCB contamination. We conclude that contamination-related male infertility may lead to a reduction in population growth via an Allee effect. The magnitude of the effect is largely dependent on the population-specific mating system. In eco-toxicological risk assessments, appropriate consideration should therefore be given to negative effects of contaminants on male fertility and male mating behaviour. © 2016 The Author(s).

Survival ability of Mexican fruit fly males from different strains in presence of the predatory orb-weaving spider Argiope argentata (Araneae: Araneidae).

PubMed

Dor, A; Liedo, P

2018-04-18

The sterile insect technique (SIT) is a key element for the integrated management of pest populations of the Mexican fruit fly, Anastrepha ludens, in Mexico. Its success depends on the survival of mass-reared sterile males and their ability to mate with wild females. However, colonization and mass-rearing conditions can adversely affect their ability to avoid predators. To test if colony management strategies could contribute to improve field survival abilities of mass-reared flies, we compared the survival of males exposed to the orb-weaver spider Argiope argentata. Males compared originated from three strains with different colonization strategies: (a) a colony started from field-collected wild flies (replacement), (b) a colony started by hybridizing wild males with mass-reared adapted females (hybrid) and (c) a colony started with mass-reared males selected on the basis of their survival ability and mating competitiveness in field cages (selected). Mass-reared males and wild males were used as controls. Males were exposed to spiders under laboratory cage conditions. Overall, wild males showed better survival ability than mass-reared males. Regarding the colonization approach, wild males survived better than a hybrid, replaced and selected males. We conclude that mass-rearing conditions have a strong negative effect on the ability of males to escape spiders. The colonization systems evaluated did not counter this effect. The lower survival of males from the selected colony suggests that the selection over one generation did not contribute to improve males' predator avoidance and escape abilities and probably needs to be modified. Possible explanations for this and implications on colonization and colony management for SIT purpose are discussed.

Interdependent effects of male and female body size plasticity on mating behaviour of predatory mites

PubMed Central

Walzer, Andreas; Schausberger, Peter

2015-01-01

The adaptive canalization hypothesis predicts that traits with low phenotypic plasticity are more fitness relevant, because they have been canalized via strong past selection, than traits with high phenotypic plasticity. Based on differing male body size plasticities of the predatory mites Phytoseiulus persimilis (low plasticity) and Neoseiulus californicus (high plasticity), we accordingly hypothesized that small male body size entails higher costs in female choice and male–male competition in P. persimilis than N. californicus. Males of both species are highly polygynous but females differ in the level of polyandry (low level in P. persimilis; medium level in N. californicus). We videotaped the mating interactions in triplets of either P. persimilis or N. californicus, consisting of a virgin female (small or standard-sized) and a small and a standard-sized male. Mating by both small and standard-sized P. persimilis females was biased towards standard-sized males, resulting from the interplay between female preference for standard-sized males and the inferiority of small males in male–male competition. In contrast, mating by N. californicus females was equally balanced between small and standard-sized males. Small N. californicus males were more aggressive (‘Napoleon complex’) in male–male competition, reducing the likelihood of encounter between the standard-sized male and the female, and thus counterbalancing female preference for standard-sized males. Our results support the hypothesis that male body size is more important to fitness in the low-level polyandrous P. persimilis than in the medium-level polyandrous N. californicus and provide a key example of the implications of sexually selected body size plasticity on mating behaviour. PMID:25673881

Condition-dependent female preference for male genitalia length is based on male reproductive tactics.

PubMed

Hernandez-Jimenez, Armando; Rios-Cardenas, Oscar

2017-12-06

There is extensive morphological variation of male genitalia across animals with internal fertilization, even among closely related species. Most studies attempting to explain this extraordinary diversity have focused on processes that occur post-copula (e.g. sperm competition, cryptic female choice). Only a few studies have focused on the pre-copula process of female preference. In addition, the extent to which this variation could be associated with the use of different reproductive tactics has yet to be explored. Here, we show that female preference for male genitalia length in two livebearing fishes depends on the type of reproductive tactic of the males being evaluated as well as the body condition of the female. In a species where all males coax females to acquire matings (courters), females preferred males with short genitalia. In a species with genetically influenced alternative reproductive tactics (courter males that only court and produce courter sons, sneaker males that use the coercive tactic of sneak chase and produce sneaker sons), female preference depended on an interaction between male tactic and female condition: females in good condition preferred courter males with short genitalia, and sneaker males with long genitalia. Our results suggest that female preference for male traits favourable to their sons may be an important factor contributing to the diversification of male genitalia. Despite the contrasting selection for genitalia length that our female preference tests suggest, we found no significant differences in genitalia length between coaxing (courters) and coercive (sneakers) males. Our study represents a starting point to more clearly understand the role of alternative reproductive tactics and variation in female mate preference in the evolution of male genitalia. © 2017 The Author(s).

Male Responses to Conspecific Advertisement Signals in the Field Cricket Gryllus rubens (Orthoptera: Gryllidae)

PubMed Central

Jang, Yikweon

2011-01-01

In many species males aggregate and produce long-range advertisement signals to attract conspecific females. The majority of the receivers of these signals are probably other males most of the time, and male responses to competitors' signals can structure the spatial and temporal organization of the breeding aggregation and affect male mating tactics. I quantified male responses to a conspecific advertisement stimulus repeatedly over three age classes in Gryllus rubens (Orthoptera: Gryllidae) in order to estimate the type and frequency of male responses to the broadcast stimulus and to determine the factors affecting them. Factors tested included body size, wing dimorphism, age, and intensity of the broadcast stimulus. Overall, males employed acoustic response more often than positive phonotactic response. As males aged, the frequency of positive phonotactic response decreased but that of the acoustic response increased. That is, males may use positive phonotaxis in the early stages of their adult lives, possibly to find suitable calling sites or parasitize calling males, and then later in life switch to acoustic responses in response to conspecific advertisement signals. Males with smaller body size more frequently exhibited acoustic responses. This study suggests that individual variation, more than any factors measured, is critical for age-dependent male responses to conspecific advertisement signals. PMID:21283758

Male responses to conspecific advertisement signals in the field cricket Gryllus rubens (Orthoptera: Gryllidae).

PubMed

Jang, Yikweon

2011-01-20

In many species males aggregate and produce long-range advertisement signals to attract conspecific females. The majority of the receivers of these signals are probably other males most of the time, and male responses to competitors' signals can structure the spatial and temporal organization of the breeding aggregation and affect male mating tactics. I quantified male responses to a conspecific advertisement stimulus repeatedly over three age classes in Gryllus rubens (Orthoptera: Gryllidae) in order to estimate the type and frequency of male responses to the broadcast stimulus and to determine the factors affecting them. Factors tested included body size, wing dimorphism, age, and intensity of the broadcast stimulus. Overall, males employed acoustic response more often than positive phonotactic response. As males aged, the frequency of positive phonotactic response decreased but that of the acoustic response increased. That is, males may use positive phonotaxis in the early stages of their adult lives, possibly to find suitable calling sites or parasitize calling males, and then later in life switch to acoustic responses in response to conspecific advertisement signals. Males with smaller body size more frequently exhibited acoustic responses. This study suggests that individual variation, more than any factors measured, is critical for age-dependent male responses to conspecific advertisement signals.

Worthless donations: male deception and female counter play in a nuptial gift-giving spider

PubMed Central

2011-01-01

Background In nuptial gift-giving species, benefits of acquiring a mate may select for male deception by donation of worthless gifts. We investigated the effect of worthless gifts on mating success in the spider Pisaura mirabilis. Males usually offer an insect prey wrapped in silk; however, worthless gifts containing inedible items are reported. We tested male mating success in the following experimental groups: protein enriched fly gift (PG), regular fly gift (FG), worthless gift (WG), or no gift (NG). Results Males that offered worthless gifts acquired similar mating success as males offering nutritional gifts, while males with no gift experienced reduced mating success. The results suggest that strong selection on the nuptial gift-giving trait facilitates male deception by donation of worthless gifts. Females terminated matings faster when males offered worthless donations; this demonstrate a cost of deception for the males as shorter matings lead to reduced sperm transfer and thus give the deceiving males a disadvantage in sperm competition. Conclusion We propose that the gift wrapping trait allows males to exploit female foraging preference by disguising the gift content thus deceiving females into mating without acquiring direct benefits. Female preference for a genuine prey gift combined with control over mating duration, however, counteracts the male deception. PMID:22082300

Worthless donations: male deception and female counter play in a nuptial gift-giving spider.

PubMed

Albo, Maria J; Winther, Gudrun; Tuni, Cristina; Toft, Søren; Bilde, Trine

2011-11-14

In nuptial gift-giving species, benefits of acquiring a mate may select for male deception by donation of worthless gifts. We investigated the effect of worthless gifts on mating success in the spider Pisaura mirabilis. Males usually offer an insect prey wrapped in silk; however, worthless gifts containing inedible items are reported. We tested male mating success in the following experimental groups: protein enriched fly gift (PG), regular fly gift (FG), worthless gift (WG), or no gift (NG). Males that offered worthless gifts acquired similar mating success as males offering nutritional gifts, while males with no gift experienced reduced mating success. The results suggest that strong selection on the nuptial gift-giving trait facilitates male deception by donation of worthless gifts. Females terminated matings faster when males offered worthless donations; this demonstrate a cost of deception for the males as shorter matings lead to reduced sperm transfer and thus give the deceiving males a disadvantage in sperm competition. We propose that the gift wrapping trait allows males to exploit female foraging preference by disguising the gift content thus deceiving females into mating without acquiring direct benefits. Female preference for a genuine prey gift combined with control over mating duration, however, counteracts the male deception.

Endocrinological correlates of male bimaturism in wild Bornean orangutans.

PubMed

Marty, Pascal R; van Noordwijk, Maria A; Heistermann, Michael; Willems, Erik P; Dunkel, Lynda P; Cadilek, Manuela; Agil, Muhammad; Weingrill, Tony

2015-11-01

Among primates, orangutans are unique in having pronounced male bimaturism leading to two fully adult morphs that differ in both physical appearance and behavior. While unflanged males have a female-like appearance, flanged males have the full suite of secondary sexual characteristics, including cheek flanges and a large throat sac. So far, hormonal correlates of arrested development in unflanged males and the expression of secondary sexual characteristics in flanged males have only been studied in zoo-housed individuals. In this study, we investigated fecal androgen and glucocorticoid metabolites as hormonal correlates of male bimaturism in 17 wild adult Bornean orangutans (Pongo pygmaeus) in Central Kalimantan, Indonesia. We predicted and found higher androgen levels in flanged males compared to unflanged males, probably due to ongoing strong competition among flanged males who meet too infrequently to establish a clear linear dominance hierarchy. Furthermore, we found no difference in fecal glucocorticoid metabolite concentrations between flanged and unflanged males, indicating that social stress is unlikely to explain arrested development in unflanged wild orangutans. The only actively developing male in our study showed significantly higher androgen levels during the period of development than later as a fully flanged male. This supports earlier findings from zoo studies that elevated androgen levels are associated with the development of secondary sexual characteristics. © 2015 Wiley Periodicals, Inc.

Sneaker “jack” males outcompete dominant “hooknose” males under sperm competition in Chinook salmon (Oncorhynchus tshawytscha)

PubMed Central

Young, Brent; Conti, David V; Dean, Matthew D

2013-01-01

In a variety of taxa, males deploy alternative reproductive tactics to secure fertilizations. In many species, small “sneaker” males attempt to steal fertilizations while avoiding encounters with larger, more aggressive, dominant males. Sneaker males usually face a number of disadvantages, including reduced access to females and the higher likelihood that upon ejaculation, their sperm face competition from other males. Nevertheless, sneaker males represent an evolutionarily stable strategy under a wide range of conditions. Game theory suggests that sneaker males compensate for these disadvantages by investing disproportionately in spermatogenesis, by producing more sperm per unit body mass (the “fair raffle”) and/or by producing higher quality sperm (the “loaded raffle”). Here, we test these models by competing sperm from sneaker “jack” males against sperm from dominant “hooknose” males in Chinook salmon. Using two complementary approaches, we reject the fair raffle in favor of the loaded raffle and estimate that jack males were ∼1.35 times as likely as hooknose males to fertilize eggs under controlled competitive conditions. Interestingly, the direction and magnitude of this skew in paternity shifted according to individual female egg donors, suggesting cryptic female choice could moderate the outcomes of sperm competition in this externally fertilizing species. PMID:24455130

A cancer-causing gene is positively correlated with male aggression in Xiphophorus cortezi

PubMed Central

Fernandez, André A.

2010-01-01

The persistence of seemingly maladaptive genes in organisms challenges evolutionary biological thought. In Xiphophorus fishes, certain melanin patterns form malignant melanomas due to a cancer-causing gene (Xiphophorus melanoma receptor kinase; Xmrk), which arose several millions years ago from unequal meiotic recombination. Xiphophorus melanomas are male biased and induced by androgens however male behavior and Xmrk genotype has not been investigated. This study found that male X. cortezi with the spotted caudal (Sc) pattern, from which melanomas originate, displayed increased aggression in mirror image trials. Furthermore, Xmrk males (regardless of Sc phenotype) bit and performed more agonistic displays than Xmrk deficient males. Male aggressive response decreased when males viewed their Sc image as compared to their non-Sc image. Collectively, these results indicate that Xmrk males experience a competitive advantage over wild-type males and that intrasexual selection could be an important component in the evolutionary maintenance of this oncogene within Xiphophorus. PMID:20021547

Male sex steroids and hormonal control of male courtship behavior in the yellow-bellied slider turtle, Trachemys scripta

USGS Publications Warehouse

Garstka, W.R.; Cooper, W.E.; Wasmund, K.W.; Lovich, J.E.

1991-01-01

Survey of androgens and estrogens in serum, liver and testes of male yellow-bellied slider turtles, Trachemys (= Pseudemys) scripta, a species exhibiting dissociated gametogenesis age-dependent melanism, revealed the presence of numerous androgen precursors, androgens, androgen metabolites, and estrogens in quantities varying with season, tissue, and male coloration.The most commonly found and abundant androgens in all males were dehydroepiandrosterone (DHEA) and androstenedione, which were present at significantly higher levels in testes than in serum or liver.Epitestosterone was found in the serum and liver of only melanistic males; testosterone was only rarely recovered.Behavioral testing of castrated male turtles implanted with various androgens, as well as intact and sham-operated controls, revealed that melanistic males courted more frequently than nonmelanistic males, and that exogenous testosterone was most effective in inducing courtship behavior in castrated males.

Heterosexual men's anger in response to male homosexuality: effects of erotic and non-erotic depictions of male-male intimacy and sexual prejudice.

PubMed

Hudepohl, Adam D; Parrott, Dominic J; Zeichner, Amos

2010-01-01

The present study compared effects of erotic and non-erotic depictions of male-male intimacy on the experience of anger in heterosexual men. Data came from three independent laboratory studies designed to elicit anger in response to erotic or non-erotic depictions of male-male and male-female intimacy. All participants completed a measure of sexual prejudice and anger was assessed before and after viewing the erotic or non-erotic video. Among high-prejudiced men, viewing erotic and non-erotic intimate behavior between two men elicited significant increases in anger relative to viewing comparable behavior between a male-female dyad. In contrast, among low-prejudiced men, viewing erotic, but not non-erotic, intimate behavior between two men elicited significant increases in anger relative to viewing comparable behavior between a male-female dyad. Implications for understanding heterosexual men's anger, and aggression, toward gay men were discussed.

Sneaker Males Affect Fighter Male Body Size and Sexual Size Dimorphism in Salmon.

PubMed

Weir, Laura K; Kindsvater, Holly K; Young, Kyle A; Reynolds, John D

2016-08-01

Large male body size is typically favored by directional sexual selection through competition for mates. However, alternative male life-history phenotypes, such as "sneakers," should decrease the strength of sexual selection acting on body size of large "fighter" males. We tested this prediction with salmon species; in southern populations, where sneakers are common, fighter males should be smaller than in northern populations, where sneakers are rare, leading to geographical clines in sexual size dimorphism (SSD). Consistent with our prediction, fighter male body size and SSD (fighter male∶female size) increase with latitude in species with sneaker males (Atlantic salmon Salmo salar and masu salmon Oncorhynchus masou) but not in species without sneakers (chum salmon Oncorhynchus keta and pink salmon Oncorhynchus gorbuscha). This is the first evidence that sneaker males affect SSD across populations and species, and it suggests that alternative male mating strategies may shape the evolution of body size.

Lethal fighting in nematodes is dependent on developmental pathway: male-male fighting in the entomopathogenic nematode Steinernema longicaudum.

PubMed

Zenner, Annemie N R L; O'Callaghan, Kathryn M; Griffin, Christine T

2014-01-01

Aggressive encounters occur between competitors (particularly males) throughout the animal kingdom, and in some species can result in severe injury and death. Here we describe for the first time lethal interactions between male nematodes and provide evidence that the expression of this behaviour is developmentally controlled. Males of the entomopathogenic nematode Steinernema longicaudum coil around each other, resulting in injuries, paralysis and frequently death. The probability of death occurring between pairs of males was affected by the developmental pathway followed, being much greater among males that had passed through the infective juvenile (IJ, or dauer) stage than among males that had not. Post-IJ males are found only in newly colonised hosts, typically with few competing males present. Killing those few competitors may secure valuable resources (both females and a host cadaver for nourishment of offspring). Non-IJ males develop in subsequent generations within a host cadaver, where the presence of many closely related male competitors increases the risk:benefit ratio of fighting. Thus, passage through the IJ stage primes males for enhanced aggression in circumstances where this is more likely to result in increased reproductive success. Fighting occurred between males developing in mixed-sex social groups, indicating that it is an evolved trait and not an abnormal response to absence of females. This is supported by finding high mortality of males, but not of females, across a range of population densities in insect cadavers. We propose that these nematodes, with their relatively simple organization, may be a useful model for studies of aggression.

Male tolerance and male-male bonds in a multilevel primate society.

PubMed

Patzelt, Annika; Kopp, Gisela H; Ndao, Ibrahima; Kalbitzer, Urs; Zinner, Dietmar; Fischer, Julia

2014-10-14

Male relationships in most species of mammals generally are characterized by intense intrasexual competition, with little bonding among unrelated individuals. In contrast, human societies are characterized by high levels of cooperation and strong bonds among both related and unrelated males. The emergence of cooperative male-male relationships has been linked to the multilevel structure of traditional human societies. Based on an analysis of the patterns of spatial and social interaction in combination with genetic relatedness data of wild Guinea baboons (Papio papio), we show that this species exhibits a multilevel social organization in which males maintain strong bonds and are highly tolerant of each other. Several "units" of males with their associated females form "parties," which team up as "gangs." Several gangs of the same "community" use the same home range. Males formed strong bonds predominantly within parties; however, these bonds were not correlated with genetic relatedness. Agonistic interactions were relatively rare and were restricted to a few dyads. Although the social organization of Guinea baboons resembles that of hamadryas baboons, we found stronger male-male affiliation and more elaborate greeting rituals among male Guinea baboons and less aggression toward females. Thus, the social relationships of male Guinea baboons differ markedly from those of other members of the genus, adding valuable comparative data to test hypotheses regarding social evolution. We suggest that this species constitutes an intriguing model to study the predictors and fitness benefits of male bonds, thus contributing to a better understanding of the evolution of this important facet of human social behavior.

Male Choice in the Stream-Anadromous Stickleback Complex

PubMed Central

McKinnon, Jeffrey S.; Hamele, Nick; Frey, Nicole; Chou, Jennifer; McAleavey, Leia; Greene, Jess; Paulson, Windi

2012-01-01

Studies of mating preferences and pre-mating reproductive isolation have often focused on females, but the potential importance of male preferences is increasingly appreciated. We investigated male behavior in the context of reproductive isolation between divergent anadromous and stream-resident populations of threespine stickleback, Gasterosteus aculeatus, using size-manipulated females of both ecotypes. Specifically, we asked if male courtship preferences are present, and if they are based on relative body size, non-size aspects of ecotype, or other traits. Because male behaviors were correlated with each other, we conducted a principal components analysis on the correlations and ran subsequent analyses on the principal components. The two male ecotypes differed in overall behavioral frequencies, with stream-resident males exhibiting consistently more vigorous and positive courtship than anadromous males, and an otherwise aggressive behavior playing a more positive role in anadromous than stream-resident courtship. We observed more vigorous courtship toward smaller females by (relatively small) stream-resident males and the reverse pattern for (relatively large) anadromous males. Thus size-assortative male courtship preferences may contribute to reproductive isolation in this system, although preferences are far from absolute. We found little indication of males responding preferentially to females of their own ecotype independent of body size. PMID:22701589

Dominance relationships among siamang males living in multimale groups.

PubMed

Morino, Luca

2016-03-01

Intense intolerance among males is considered to be an important mechanism maintaining the uni-male organization traditionally attributed to socially monogamous gibbons. Long-term field work, however, has revealed the existence of stable, socially polyandrous groups in at least two populations, raising questions about the mechanism that allows two adult males to co-reside in the same group. I collected 21 months of behavioral data on 7 two-male groups of wild siamangs (Symphalangus syndactylus) in southern Sumatra (Indonesia) to test the hypothesis that dominance relationships regulate the interactions of adult male siamangs and ultimately facilitate multi-male social groups. A dominant male could clearly be identified in each dyad, based on a consistent direction of agonistic interactions, displacements and the maintenance of an advantageous position in the canopy. Males identified as dominant enjoyed greater social access to the resident female and monopolized copulations. These results suggest that gibbons possess the psycho-social flexibility to regulate intra-sexual aggression and live in multi-male social units under certain social conditions. I discuss the effects that relatedness between males and female choice have in determining this grouping pattern, and the role of male intolerance in the maintenance of primate mating systems. © 2015 Wiley Periodicals, Inc.

Mothers matter! Maternal support, dominance status and mating success in male bonobos (Pan paniscus).

PubMed

Surbeck, Martin; Mundry, Roger; Hohmann, Gottfried

2011-02-22

Variation in male mating success is often related to rank differences. Males who are unable to monopolize oestrous females alone may engage in coalitions, thus enhancing their mating success. While studies on chimpanzees and dolphins suggest that coalitions are independent of kinship, information from female philopatric species shows the importance of kin support, especially from mothers, on the reproductive success of females. Therefore, one might expect a similar effect on sons in male philopatric species. We evaluate mating success determinants in male bonobos using data from nine male individuals from a wild population. Results reveal a steep, linear male dominance hierarchy and a positive correlation between dominance status and mating success. In addition to rank, the presence of mothers enhances the mating success of sons and reduces the proportion of matings by the highest ranking male. Mothers and sons have high association rates and mothers provide agonistic aid to sons in conflicts with other males. As bonobos are male-philopatric and adult females occupy high dominance status, maternal support extends into adulthood and females have the leverage to intervene in male conflicts. The absence of female support to unrelated males suggests that mothers gain indirect fitness benefits by supporting their sons.

Lack of differences between males with or without perceived same sex attraction.

PubMed

Lee, Peter A; Houk, Christopher P

2006-02-01

Adolescent males are often concerned that they may be homosexual because of a sense of sexual attraction to other males. This not uncommon concern is often expressed to pediatric endocrinologists who come into contact with these boys because of concerns with abnormal pubertal development. To explore the character and prevalence of these types of homosexual concerns we assessed the perceptions of a group of healthy adolescent males using a structured questionnaire. The aim of this study was to determine whether males concerned about homosexual tendencies manifest a unique self-perception profile or interact differently with others. A multi-item questionnaire regarding demographic, behavioral, psychological and sexual characteristics was administered to 52 18-24 year-old males. Overall, there were few differences between males admitting to an adolescent homosexual attraction to males and males without this attraction. Differences between these two groups included more exposure to some kinds of pornography (including male to male imagery), noticeable psychosexual responses to male pornography, internal questioning over homosexual tendencies, comparisons of genitalia and perceptions of body build. There were no differences in demographics, family structure, religious beliefs, socio-economic status, knowledge of puberty, inter-personal relationships or sources of information about sexuality.

Information content and acoustic structure of male African elephant social rumbles

PubMed Central

Stoeger, Angela S.; Baotic, Anton

2016-01-01

Until recently, the prevailing theory about male African elephants (Loxodonta africana) was that, once adult and sexually mature, males are solitary and targeted only at finding estrous females. While this is true during the state of ‘musth’ (a condition characterized by aggressive behavior and elevated androgen levels), ‘non-musth’ males exhibit a social system seemingly based on companionship, dominance and established hierarchies. Research on elephant vocal communication has so far focused on females, and very little is known about the acoustic structure and the information content of male vocalizations. Using the source and filter theory approach, we analyzed social rumbles of 10 male African elephants. Our results reveal that male rumbles encode information about individuality and maturity (age and size), with formant frequencies and absolute fundamental frequency values having the most informative power. This first comprehensive study on male elephant vocalizations gives important indications on their potential functional relevance for male-male and male-female communication. Our results suggest that, similar to the highly social females, future research on male elephant vocal behavior will reveal a complex communication system in which social knowledge, companionship, hierarchy, reproductive competition and the need to communicate over long distances play key roles. PMID:27273586

Polygyny, mate-guarding, and posthumous fertilization as alternative male mating strategies

PubMed Central

Zamudio, Kelly R.; Sinervo, Barry

2000-01-01

Alternative male mating strategies within populations are thought to be evolutionarily stable because different behaviors allow each male type to successfully gain access to females. Although alternative male strategies are widespread among animals, quantitative evidence for the success of discrete male strategies is available for only a few systems. We use nuclear microsatellites to estimate the paternity rates of three male lizard strategies previously modeled as a rock-paper-scissors game. Each strategy has strengths that allow it to outcompete one morph, and weaknesses that leave it vulnerable to the strategy of another. Blue-throated males mate-guard their females and avoid cuckoldry by yellow-throated “sneaker” males, but mate-guarding is ineffective against aggressive orange-throated neighbors. The ultradominant orange-throated males are highly polygynous and maintain large territories; they overpower blue-throated neighbors and cosire offspring with their females, but are often cuckolded by yellow-throated males. Finally, yellow-throated sneaker males sire offspring via secretive copulations and often share paternity of offspring within a female's clutch. Sneaker males sire more offspring posthumously, indicating that sperm competition may be an important component of their strategy. PMID:11106369

Brain and gonadal aromatase activity and steroid hormone levels in female and polymorphic males of the peacock blenny Salaria pavo.

PubMed

Gonçalves, David; Teles, Magda; Alpedrinha, João; Oliveira, Rui F

2008-11-01

In the peacock blenny Salaria pavo large males with well-developed secondary sexual characters establish nests and attract females while small "sneaker" males mimic female sexual displays in order to approach the nests of larger males and parasitically fertilize eggs. These alternative reproductive tactics are sequential, as sneakers irreversibly switch into nesting males. This transition involves major morphologic and behavioral changes and is likely to be mediated by hormones. This study focuses on the role of aromatase, an enzyme that catalyses the conversion of androgens into estrogens, in the regulation of male sexual polymorphism in S. pavo. For this, sex steroid plasma levels and aromatase activity (AA) in gonads, whole brain and brain macroareas were determined in sneakers, transitional males (i.e. sneakers undergoing the transition into nesting males), nesting males and females collected in the field. AA was much higher in ovarian tissue than in testicular tissue and accordingly circulating estradiol levels were highest in females. This supports the view that elevated AA and estradiol levels are associated with the development of a functional ovary. Transitional males are in a non-reproductive phase and had underdeveloped testes when compared with sneakers and nesting males. Testicular AA was approximately 10 times higher in transitional males when compared with sneakers and nesting males, suggesting high AA has a suppressive effect on testicular development. Nesting males had significantly higher plasma levels of both testosterone (T) and 11-ketotestosterone when compared with the other male morphs and previous studies demonstrated that these androgens suppress female-like displays in sneakers. In the brain, AA was highest in macroareas presumably containing hypothalamic nuclei traditionally associated with the regulation of reproductive behaviors. Overall, females presented the highest levels of brain AA. In male morphs AA increased from sneakers, to transitional males, to nesting males in all brain macroareas. These results suggest that the transition into the nesting male tactic is accompanied both by an increase in testicular androgen production and by a higher conversion of androgens into estrogens in the brain. The increase in androgen production is likely to mediate the development of male secondary sexual characters while the increase in brain AA may be related to the behavioral changes associated with tactic transition.

Mating behavior of adolescent male chimpanzees (Pan troglodytes) at Ngogo, Kibale National Park, Uganda.

PubMed

Watts, David P

2015-04-01

Male mating tactics vary extensively in many primates. Some variation occurs because adolescent males often are sexually active but cannot invest heavily in mating effort because of their limited ability to compete directly with adults and because they are still investing in growth; consequently, most of their mating attempts may be surreptitious and/or with females whose fecundity is low. Chimpanzees (Pan troglodytes) have a complex mating system: most copulations occur between estrous females with full sexual swelling and multiple males in group settings where the potential for sperm competition is high, but males sometimes mate-guard females, and sometimes male-female pairs mate exclusively with each other while avoiding other males during "consortships." Among other factors, dominance ranks, coalition formation, and variation in male-female association influence male mating and reproductive success. Mating effort increases from adolescence into prime adulthood. At Gombe and Mahale, adolescent males copulated more with nulliparous than with parous females, and mostly when females were unlikely to be ovulating, partly because of low adult male interest in nulliparous females and partly because of aggression from or avoidance of adult males. Adolescents thus had low probabilities of siring infants. However, adolescents are known to have gained some paternity at Gombe and in other populations, and their mating behavior deserves more study. I present data on mating by adolescent males in an unusually large chimpanzee community at Ngogo, Kibale National Park, Uganda. Adolescents at Ngogo also copulated more with nulliparous than parous females and mostly copulated outside of periovulatory periods. Also, they directed less aggression at estrous females than did adult males. However, they gained lower shares of copulations than reported for Gombe and Mahale, regardless of female parity, and received more aggression from adult males. These differences might partly reflect the influence of variation in the number of males per community on male mating tactics.

Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens).

PubMed

Utne-Palm, A C; Eduard, K; Jensen, K H; Mayer, I; Jakobsen, P J

2015-01-01

Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG) of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG) mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate availability and male--male competition.

Social constructions of the male contraception pill: When are we going to break the vicious circle?

PubMed

Dismore, Lorelle; Van Wersch, Anna; Swainston, Katherine

2016-05-01

Social constructions of men towards the availability of a male hormonal contraceptive, the 'male pill', were explored. A qualitative approach applying semi-structured interviews and scenarios with 22 men (mean age 35 years) from the North East of England revealed two core constructs and six sub-constructs using a Thematic-Construct Analysis in line with the method of Toerien and Wilkinson and Clarke and Kitzinger. Verbal accounts were inductively used to balance the deductively created two core constructs 'Constructing the male pill norm: dominant system of sensemaking' and 'Living by the male pill norm' to represent a normative framework within a changing ideology of shared responsibility in contraceptive choice. Constructing the male pill norm was divided into two sub-constructs: 'Male pill: we are going to join the women and become responsible - too!' and 'Male pill: you look so girly - what are they going to think of me?' The 'Living by the male pill norm' was further divided into four sub-constructs 'Male pill - thank you for giving me promises not to have to become a dad as yet!'; 'Male pill: thank you for the idea of fun - sorry about my morals!'; 'Male pill: in stable relations - yes, I would have you now - sorry, I am too late!' and 'Male pill, we love you - but we are too anxious - we are not ready as yet!' From this male discourse, it is clear that discussions over the male pill follow the line of a vicious circle. In order to establish long-term side effects, Phase IV studies are necessary, and these cannot commence without the male hormonal contraception being a marketable product. So, unless this circle gets broken by some brave men, the male pill will remain a virtual rotating idea for a long time. © The Author(s) 2014.

An Essential Role of the Arginine Vasotocin System in Mate-Guarding Behaviors in Triadic Relationships of Medaka Fish (Oryzias latipes)

PubMed Central

Yokoi, Saori; Okuyama, Teruhiro; Kamei, Yasuhiro; Naruse, Kiyoshi; Taniguchi, Yoshihito; Ansai, Satoshi; Kinoshita, Masato; Young, Larry J.; Takemori, Nobuaki; Kubo, Takeo; Takeuchi, Hideaki

2015-01-01

To increase individual male fitness, males of various species remain near a (potential) mating partner and repel their rivals (mate-guarding). Mate-guarding is assumed to be mediated by two different types of motivation: sexual motivation toward the opposite sex and competitive motivation toward the same sex. The genetic/molecular mechanisms underlying how mate presence affects male competitive motivation in a triadic relationship has remained largely unknown. Here we showed that male medaka fish prominently exhibit mate-guarding behavior. The presence of a female robustly triggers male-male competition for the female in a triadic relationship (2 males and 1 female). The male-male competition resulted in one male occupying a dominant position near the female while interfering with the other male's approach of the female. Paternity testing revealed that the dominant male had a significantly higher mating success rate than the other male in a triadic relationship. We next generated medaka mutants of arginine-vasotocin (avt) and its receptors (V1a1, V1a2) and revealed that two genes, avt and V1a2, are required for normal mate-guarding behavior. In addition, behavioral analysis of courtship behaviors in a dyadic relationship and aggressive behaviors within a male group revealed that avt mutant males displayed decreased sexual motivation but showed normal aggression. In contrast, heterozygote V1a2 mutant males displayed decreased aggression, but normal mate-guarding and courtship behavior. Thus, impaired mate-guarding in avt and V1a2 homozygote mutants may be due to the loss of sexual motivation toward the opposite sex, and not to the loss of competitive motivation toward rival males. The different behavioral phenotypes between avt, V1a2 heterozygote, and V1a2 homozygote mutants suggest that there are redundant systems to activate V1a2 and that endogenous ligands activating the receptor may differ according to the social context. PMID:25719383

Homophobia, perceived fathering, and male intimate relationships.

PubMed

Devlin, P K; Cowan, G A

1985-10-01

This study examined the relationships among homophobia, perceived fathering, and male intimacy with significant male and female best friends. A questionnaire, administered to 130 adult heterosexual males, included McDonald and Game's homophobia measure (ATHMS), eight intimacy scales, and four scales measuring subjects' recollections of their fathers' parenting styles. Correlations of ATHMS and individual intimacy scales revealed a significant relationship between homophobia and intimacy in male-male relationships. Homophobia was related to male-female intimacy on those measures which reflected subjects' perception of their female partner's sensitivity to them. Although homophobia was related to perception of the father as enforcing sex roles, none of the perceived fathering variables were directly related to intimacy with males. The findings provide evidence for a direct relationship between male homophobia and lack of intimacy in friendships between men.

Vitamin D is necessary for reproductive functions of the male rat.

PubMed

Kwiecinski, G G; Petrie, G I; DeLuca, H F

1989-05-01

The effect of vitamin D deficiency on the fertility and reproductive capacity of male rats was investigated. Male weanling rats were fed vitamin D-deficient or vitamin D-replete diets until maturity, and mated to age-matched, vitamin D-replete females. Vitamin D-deficient males were capable of reproduction. However, successful matings, i.e., presence of sperm in the vaginal tract of the female, by vitamin D-deficient males were reduced by 45% when compared to matings by vitamin D-replete males. Fertility (successful pregnancies in sperm-positive females) was reduced by 73% in litters from vitamin D-deficient male inseminations when compared to litters from females inseminated by vitamin D-replete males. These results demonstrate that vitamin D and its metabolites are necessary for normal reproductive functions in the male rat.

Sex-specific rejection in mate-guarding pair formation in the intertidal copepod, Tigriopus californicus

PubMed Central

Burton, Ronald S.

2017-01-01

Securing a potential mate is one of the most important processes in sexual reproduction of animals. Intertidal copepods of the genus Tigriopus show mate-guarding behavior where a male captures a female and continues to clasp her for up to two weeks prior to copulation. Although these copepods form a mate-guarding pair between a male and a female with high accuracy, interactions between the sexes in pair formation have not been well described and the mechanism allowing successful male-female pair formation is not yet understood. In this study, we performed experiments with Tigriopus californicus to analyze the behavior of both a capturer (male) and a captured individual (female or male) in formation of a guarding pair. While capturer males were attracted by both females and males, capture of virgin males was terminated in a significantly shorter time than that of virgin females. However, when presented freshly killed females or males, regardless of the sex of the body, capturer males continued to clasp the body for a comparable time as in an attempt on a living female. Our results suggest that a sex-specific rejection signal actively sent by captured males prevents male-male pair formation. Experiments also suggest that mated females reject an attempt of pair formation. To our knowledge, this is the first study to suggest involvement of active rejection by a captured individual in facilitation of reproductively successful male-female guarding pair formation in the genus Tigriopus. PMID:28832683

Imperfect chemical female mimicry in males of the ant Cardiocondyla obscurior

NASA Astrophysics Data System (ADS)

Cremer, Sylvia; D'Ettorre, Patrizia; Drijfhout, Falko P.; Sledge, Matthew F.; Turillazzi, Stefano; Heinze, Jürgen

2008-11-01

Winged and wingless males coexist in the ant Cardiocondyla obscurior. Wingless (“ergatoid”) males never leave their maternal colony and fight remorselessly among each other for the access to emerging females. The peaceful winged males disperse after about 10 days, but beforehand also mate in the nest. In the first 5 days of their life, winged males perform a chemical female mimicry that protects them against attack and even makes them sexually attractive to ergatoid males. When older, the chemical profile of winged males no longer matches that of virgin females; nevertheless, they are still tolerated, which so far has been puzzling. Contrasting this general pattern, we have identified a single aberrant colony in which all winged males were attacked and killed by the ergatoid males. A comparative analysis of the morphology and chemical profile of these untypical attacked winged males and the tolerated males from several normal colonies revealed that normal old males are still performing some chemical mimicry to the virgin queens, though less perfect than in their young ages. The anomalous attacked winged males, on the other hand, had a very different odour to the females. Our study thus exemplifies that the analysis of rare malfunctioning can add valuable insight on functioning under normal conditions and allows the conclusion that older winged males from normal colonies of the ant C. obscurior are guarded through an imperfect chemical female mimicry, still close enough to protect against attacks by the wingless fighters yet dissimilar enough not to elicit their sexual interest.

Alternative male morphs solve sperm performance/longevity trade-off in opposite directions.

PubMed

Taborsky, Michael; Schütz, Dolores; Goffinet, Olivier; van Doorn, G Sander

2018-05-01

Males pursuing alternative reproductive tactics have been predicted to face a trade-off between maximizing either swimming performance or endurance of their sperm. However, empirical evidence for this trade-off is equivocal, which may be due to simplistic assumptions. In the shell-brooding cichlid fish Lamprologus callipterus , two Mendelian male morphs compete for fertilization by divergent means: Bourgeois nest males ejaculate sperm, on average, about six times farther from the unfertilized ova than do parasitic dwarf males. This asymmetry is opposite to the usual situation, in which bourgeois males typically benefit from superior fertilization opportunities, suggesting that nest males' sperm should persist longer than dwarf male sperm. The assumed trade-off between sperm swimming performance and longevity predicts that, in turn, sperm of dwarf males should outperform that of nest males in swimming efficiency. Measurement of sperm performance and endurance reveals that dwarf male spermatozoa swim straighter initially than those of nest males, but their motility declines earlier and their velocity slows down more abruptly. Nest male sperm survives longer, which relates to a larger sperm head plus midpiece, implying more mitochondria. Thus, the trade-off between sperm performance and endurance is optimized in opposite directions by alternative male morphs. We argue that the relative success of alternative sperm performance strategies can be influenced strongly by environmental factors such as the time window between gamete release and fertilization, and the position of gamete release. This is an important yet little understood aspect of gametic adaptations to sperm competition.

Characterizing Male–Female Interactions Using Natural Genetic Variation in Drosophila melanogaster

PubMed Central

Reinhart, Michael; Carney, Tara; Clark, Andrew G.

2015-01-01

Drosophila melanogaster females commonly mate with multiple males establishing the opportunity for pre- and postcopulatory sexual selection. Traits impacting sexual selection can be affected by a complex interplay of the genotypes of the competing males, the genotype of the female, and compatibilities between the males and females. We scored males from 96 2nd and 94 3rd chromosome substitution lines for traits affecting reproductive success when mated with females from 3 different genetic backgrounds. The traits included male-induced female refractoriness, male remating ability, the proportion of offspring sired under competitive conditions and male-induced female fecundity. We observed significant effects of male line, female genetic background, and strong male by female interactions. Some males appeared to be “generalists” and performed consistently across the different females; other males appeared to be “specialists” and performed very well with a particular female and poorly with others. “Specialist” males did not, however, prefer to court those females with whom they had the highest reproductive fitness. Using 143 polymorphisms in male reproductive genes, we mapped several genes that had consistent effects across the different females including a derived, high fitness allele in Acp26Aa that may be the target of adaptive evolution. We also identified a polymorphism upstream of PebII that may interact with the female genetic background to affect male-induced refractoriness to remating. These results suggest that natural variation in PebII might contribute to the observed male–female interactions. PMID:25425680

Intraspecific variation in estrogen receptor alpha and the expression of male sociosexual behavior in two populations of prairie voles.

PubMed

Cushing, Bruce S; Razzoli, Maria; Murphy, Anne Z; Epperson, Pamela M; Le, Wei-Wei; Hoffman, Gloria E

2004-08-06

Estrogen (E) regulates a variety of male sociosexual behaviors. We hypothesize that there is a relationship between the distribution of estrogen receptor alpha (ERalpha) and the degree of male social behavior. To test this hypothesis, ERalpha immunoreactivity (IR) was compared in prairie voles (Microtus ochrogaster) from Illinois (IL), which are highly social, and Kansas (KN), which are less social. The expression of androgen receptors (AR) in males also was compared between populations. The expression of ERalpha and AR were compared in brains from KN and IL males and females using immunocytochemistry (ICC). There were significant intrapopulational differences, with males expressing less ERalpha-IR than females in the medial preoptic area, ventromedial nucleus, ventrolateral portion of the hypothalamus, and bed nucleus of the stria terminalis (BST). IL males also displayed less ERalpha-IR in the medial amygdala (MeA) than IL females. While IL males expressed significantly less ERalpha-IR in the BST and MeA than KN males, there was no difference in AR-IR. Differences in the pattern of ERalpha-IR between KN and IL males were behaviorally relevant, as low levels of testosterone (T) were more effective in restoring sexual activity in castrated KN males than IL males. The lack of difference in AR combined with lower expression of ERalpha-IR in IL males suggests that behavioral differences in response to T are associated with aromatization of T to E and that reduced sensitivity to E may facilitate prosocial behavior in males.

Breast cancer in men

MedlinePlus

... in situ - male; Intraductal carcinoma - male; Inflammatory breast cancer - male; Paget disease of the nipple - male; Breast cancer - male ... The cause of breast cancer in men is not clear. But there are risk factors that make breast cancer more likely in men: Exposure to ...

The effect of female wings on male courtship behavior in the cricket Gryllus bimaculatus

NASA Astrophysics Data System (ADS)

Itoh, Masanori; Murakami, Shio

2002-03-01

Sexual dimorphism exists in the shape and the structure of the forewings of the cricket (Gryllus bimaculatus). However, the functional significance of the wings in the G. bimaculatus female has been unclear. In common blue butterflies (Polyommatus icarus), wings in females have been suggested as being important for attracting males. To test whether female crickets need wings for conspecific males to recognize them and initiate mating behavior, we removed all wings from females and observed the behavior of males towards them. Most males (87.5%) showed mating behavior towards the wingless females: they produced courtship song and transferred spermatophores to the wingless females. Similarly, 88.5% of the males showed mating behavior towards intact females. When males were placed with both a wingless female and an intact female, no significant difference was detected in male mate choice. The findings demonstrate that the wing of the G. bimaculatus female is not necessary for female recognition by conspecific males and the initiation of male mating behavior, and that it is not important in male mate choice.

Living on the wedge: female control of paternity in a cooperatively polyandrous cichlid

PubMed Central

Kohda, Masanori; Heg, Dik; Makino, Yoshimi; Takeyama, Tomohiro; Shibata, Jun-ya; Watanabe, Katsutoshi; Munehara, Hiroyuki; Hori, Michio; Awata, Satoshi

2009-01-01

Theories suggest that, in cooperatively breeding species, female control over paternity and reproductive output may affect male reproductive skew and group stability. Female paternity control may come about through cryptic female choice or female reproductive behaviour, but experimental studies are scarce. Here, we show a new form of female paternity control in a cooperatively polyandrous cichlid fish (Julidochromis transcriptus), in which females prefer wedge-shaped nesting sites. Wedge-shaped sites allowed females to manipulate the siring success of the group member males by spawning the clutch at the spot where the large males were just able to enter and fertilize the outer part of the clutch. Small males fertilized the inner part of the clutch, protected from the large aggressive males, leading to low male reproductive skew. Small males provided more brood care than large males. Multiple paternity induced both males to provide brood care and reduced female brood care accordingly. This is, to our knowledge, the first documented case in a species with external fertilization showing female mating behaviour leading to multiple male paternity and increased male brood care as a result. PMID:19726479

Eavesdropping and signal matching in visual courtship displays of spiders.

PubMed

Clark, David L; Roberts, J Andrew; Uetz, George W

2012-06-23

Eavesdropping on communication is widespread among animals, e.g. bystanders observing male-male contests, female mate choice copying and predator detection of prey cues. Some animals also exhibit signal matching, e.g. overlapping of competitors' acoustic signals in aggressive interactions. Fewer studies have examined male eavesdropping on conspecific courtship, although males could increase mating success by attending to others' behaviour and displaying whenever courtship is detected. In this study, we show that field-experienced male Schizocosa ocreata wolf spiders exhibit eavesdropping and signal matching when exposed to video playback of courting male conspecifics. Male spiders had longer bouts of interaction with a courting male stimulus, and more bouts of courtship signalling during and after the presence of a male on the video screen. Rates of courtship (leg tapping) displayed by individual focal males were correlated with the rates of the video exemplar to which they were exposed. These findings suggest male wolf spiders might gain information by eavesdropping on conspecific courtship and adjust performance to match that of rivals. This represents a novel finding, as these behaviours have previously been seen primarily among vertebrates.

Alternative Mating Tactics in Male Chameleons (Chamaeleo chamaeleon) Are Evident in Both Long-Term Body Color and Short-Term Courtship Pattern

PubMed Central

Keren-Rotem, Tammy; Levy, Noga; Wolf, Lior; Bouskila, Amos; Geffen, Eli

2016-01-01

Alternative mating tactics in males of various taxa are associated with body color, body size, and social status. Chameleons are known for their ability to change body color following immediate environmental or social stimuli. In this study, we examined whether the differential appearance of male common chameleon during the breeding season is indeed an expression of alternative mating tactics. We documented body color of males and used computer vision techniques to classify images of individuals into discrete color patterns associated with seasons, individual characteristics, and social contexts. Our findings revealed no differences in body color and color patterns among males during the non-breeding season. However, during the breeding season males appeared in several color displays, which reflected body size, social status, and behavioral patterns. Furthermore, smaller and younger males resembled the appearance of small females. Consequently, we suggest that long-term color change in males during the breeding season reflects male alternative mating tactics. Upon encounter with a receptive female, males rapidly alter their appearance to that of a specific brief courtship display, which reflects their social status. The females, however, copulated indiscriminately in respect to male color patterns. Thus, we suggest that the differential color patterns displayed by males during the breeding season are largely aimed at inter-male signaling. PMID:27409771

Attitudes towards the male contraceptive pill in men and women in casual and stable sexual relationships.

PubMed

Eberhardt, Judith; van Wersch, Anna; Meikle, Neil

2009-07-01

Men's and women's attitudes towards the male contraceptive pill and their trust in the effective use of the male pill were investigated, as well as the associated variables of reported health behaviours, perceived self-efficacy and type of sexual relationship, using a questionnaire survey. Although both sexes had a favourable attitude towards the male pill, females had a more positive attitude than men. Conversely, women had less trust that men would use the male pill effectively. Males in stable sexual relationships were more positive about the male pill than those in casual sexual relationships. Gender, relationship type and trust in the effective use of the male pill reliably predicted attitude towards the male pill. High perceived self-efficacy was related to engaging in more health behaviours, and in men a positive association between health behaviours and attitude towards the male pill has been found. A positive attitude towards the male pill does not automatically imply that the individual is confident about its effective use. Once the male pill is widely available, promotional campaigns could target not only men but also their female partners, as the latter tend to come into contact with health services more frequently. In order to increase confidence in effective implementation, a variety of presentations of the male pill should be made available in line with individual needs and lifestyles.

Generation of male differentiated germ cells from various types of stem cells.

PubMed

Hou, Jingmei; Yang, Shi; Yang, Hao; Liu, Yang; Liu, Yun; Hai, Yanan; Chen, Zheng; Guo, Ying; Gong, Yuehua; Gao, Wei-Qiang; Li, Zheng; He, Zuping

2014-06-01

Infertility is a major and largely incurable disease caused by disruption and loss of germ cells. It affects 10-15% of couples, and male factor accounts for half of the cases. To obtain human male germ cells 'especially functional spermatids' is essential for treating male infertility. Currently, much progress has been made on generating male germ cells, including spermatogonia, spermatocytes, and spermatids, from various types of stem cells. These germ cells can also be used in investigation of the pathology of male infertility. In this review, we focused on advances on obtaining male differentiated germ cells from different kinds of stem cells, with an emphasis on the embryonic stem (ES) cells, the induced pluripotent stem (iPS) cells, and spermatogonial stem cells (SSCs). We illustrated the generation of male differentiated germ cells from ES cells, iPS cells and SSCs, and we summarized the phenotype for these stem cells, spermatocytes and spermatids. Moreover, we address the differentiation potentials of ES cells, iPS cells and SSCs. We also highlight the advantages, disadvantages and concerns on derivation of the differentiated male germ cells from several types of stem cells. The ability of generating mature and functional male gametes from stem cells could enable us to understand the precise etiology of male infertility and offer an invaluable source of autologous male gametes for treating male infertility of azoospermia patients. © 2014 Society for Reproduction and Fertility.

Male ruff colour as a rank signal in a monomorphic-horned mammal: behavioural correlates

NASA Astrophysics Data System (ADS)

Lovari, S.; Fattorini, N.; Boesi, R.; Bocci, A.

2015-08-01

Coexistence of individuals within a social group is possible through the establishment of a hierarchy. Social dominance is achieved through aggressive interactions, and, in wild sheep and goats, it is related mainly to age, body size and weapon size as rank signals. Adult male Himalayan tahr are much larger than females and subadult males. They have a prominent neck ruff, ranging in colour from yellow (5.5-9.5 years old, i.e. young adults, golden males) to brown (7.5-14.5 years old, i.e. older individuals, pale and dark brown males), with golden males being the most dominant. We investigated the social behaviour of male tahr and analysed the relationships between ruff colour, courtship and agonistic behaviour patterns during the rut. Colour classes varied in their use of several behaviour patterns (male dominance: approach, stare, horning vegetation; courtship: low stretch, naso- genital contact, rush). Golden-ruffed males used more threats than darker ones. Pale brown and dark brown males addressed threats significantly more often to males of lower or their own colour classes, respectively, whereas golden ones addressed threats to all colour classes, including their own. The courtship of dominant males was characterised by the assertive rush, whereas that of subordinates did not. Ruff colour of male Himalayan tahr may have evolved as a rank signal, homologous to horn size in wild sheep and goats.

Older males signal more reliably.

PubMed Central

Proulx, Stephen R; Day, Troy; Rowe, Locke

2002-01-01

The hypothesis that females prefer older males because they have higher mean fitness than younger males has been the centre of recent controversy. These discussions have focused on the success of a female who prefers males of a particular age class when age cues, but not quality cues, are available. Thus, if the distribution of male quality changes with age, such that older males have on average genotypes with higher fitness than younger males, then a female who mates with older males has fitter offspring, which allows the female preference to spread through a genetic correlation. We develop a general model for male display in a species with multiple reproductive bouts that allows us to identify the conditions that promote reliable signalling within an age class. Because males have opportunities for future reproduction, they will reduce their levels of advertising compared with a semelparous species. In addition, because higher-quality males have more future reproduction, they will reduce their advertising more than low-quality males. Thus, the conditions for reliable signalling in a semelparous organism are generally not sufficient to produce reliable signalling in species with multiple reproductive bouts. This result is due to the possibility of future reproduction so that, as individuals age and the opportunities for future reproduction fade, signalling becomes more reliable. This provides a novel rationale for female preference for older mates; older males reveal more information in their sexual displays. PMID:12495495

Parker's sneak-guard model revisited: why do reproductively parasitic males heavily invest in testes?

NASA Astrophysics Data System (ADS)

Ota, Kazutaka; Kohda, Masanori; Hori, Michio; Sato, Tetsu

2011-10-01

Alternative reproductive tactics are widespread in males and may cause intraspecific differences in testes investment. Parker's sneak-guard model predicts that sneaker males, who mate under sperm competition risk, invest in testes relatively more than bourgeois conspecifics that have lower risk. Given that sneakers are much smaller than bourgeois males, sneakers may increase testes investment to overcome their limited sperm productivity because of their small body sizes. In this study, we examined the mechanism that mediates differential testes investment across tactics in the Lake Tanganyika cichlid fish Lamprologus callipterus. In the Rumonge population of Burundi, bourgeois males are small compared with those in other populations and have a body size close to sneaky dwarf males. Therefore, if differences in relative testis investment depend on sperm competition, the rank order of relative testis investment should be dwarf males > bourgeois males in Rumonge = bourgeois males in the other populations. If differences in relative testis investment depend on body size, the rank order of relative testes investment should be dwarf males > bourgeois males in Rumonge > bourgeois males in the other populations. Comparisons of relative testis investment among the three male groups supported the role of sperm competition, as predicted by the sneak-guard model. Nevertheless, the effects of absolute body size on testes investment should be considered to understand the mechanisms underlying intraspecific variation in testes investment caused by alternative reproductive tactics.

77 FR 58379 - Change in Bank Control Notices; Acquisitions of Shares of a Bank or Bank Holding Company

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-20

... Memorial Drive, Kansas City, Missouri 64198-0001: 1. The Males Family Trust and Males 2010 Trust, Mikael Lowell Males, trustee; Mikael Lowell Males, individually, and all as members of the Males Family Group...

One-male units and clans in a colony of hamadryas baboons (Papio hamadryas hamadryas): effect of male number and clan cohesion on feeding success.

PubMed

Colmenares, Fernando; Esteban, Marta M; Zaragoza, Félix

2006-01-01

In the multilevel societies of hamadryas baboons, adult males can be attached to single one-male units (OMUs) or to clans containing several such OMUs. This paper examines the effect of male number and rivalry between males within a clan on their ability to compete for access to a clumped food resource. The data come from a study of a multilevel colony of hamadryas baboons (Papio hamadryas hamadryas) housed at the Madrid Zoo. The colony consisted of 12 harem-holding males and 40 sexually mature females, and was organized into five single OMUs and two clans (containing three and four OMUs, respectively). The top-ranking male of one of the clans was removed and later reintroduced, so the study involved an analysis of the composition of clans and OMUs and of the males' use of the feeding area across three study periods: preseparation, separation, and reintroduction. The findings reported indicate that both males and females derived clear advantages in the context of contest competition for access to clumped food if they were members of clans, because the males and females from large clans had a feeding advantage over those from smaller clans and single OMUs. Furthermore, rivalry among males within the clan reduced their ability to compete for food against males outside their clan. This paper provides empirical evidence for one of the potential advantages that hamadryas males may enjoy if they are attached to clans, and also provides empirical support for the general hypothesis that a large number of males in a group may provide fitness-related benefits to the group members, provided they are able to cooperate with each other. 2006 Wiley-Liss, Inc.

Sexual selection in Drosophila silvestris of Hawaii.

PubMed

Spiess, E B; Carson, H L

1981-05-01

Previous discovery that Drosophila melanogaster females tend to discriminate in mating against phenotypes of earliest courting males prompted a study of the Hawaiian species D. silvestris. Tibial bristle variation in males from opposite coasts of the island of Hawaii functions in courtship, and the possibility that females can distinguish males differing in the tibial trait is explored. Mating tests, designed to give each female and male an alternative choice between two individuals of opposite sex every 30 min, consisted of intrapopulation tests with a strain derived from an eastern (Kilauea) population and interpopulation tests between that strain and one derived from a western (Kahuku) population. Males were given initial combat tests, with "winners" then used in mating (except one test with "loser" males). Matings (52-55%) were classified into categories according to the readiness of the female to mate and sequence of courtship. Low-threshold females (accepting the first male after less than four courtship bouts) occurred at 30-35%. Among intrapopulational tests, females (with higher threshold) accepted first- and second-courting males about equally (25:36, respectively), but for male success in mating, the winning of initial intermale combats and the uniformity of courtship effort tended to be important criteria. Among interpopulation tests, homogamic matings were nearly equal (25% each), but heterogamic matings contrasted in that Kilauea females were reluctant to mate with Kahuku males (14%), while reciprocal matings occurred most frequently (34%). Females favored males second to court, particularly when a Kilauea male (with extra tibial bristles) was the second male. Thus a morphological feature likely to be influential in mating is demonstrated to be so; and sexual selection is operating via male-male combat plus discrimination in favor of particular opposite-sex individuals in this species.

Heat stress affects male reproduction in a parasitoid wasp.

PubMed

Nguyen, Thanh Manh; Bressac, Christophe; Chevrier, Claude

2013-03-01

In insects, reproductive success and survival are affected by temperature. Reproduction is more sensitive than other physiological traits. While the effects of heat stress on females are well known, the effects on males are less clear. Hymenopteran parasitoids are valuable for studying the consequences of heat stress on male reproduction. In these species, through arrhenotoquous parthenogenesis, the sex ratio of the offspring is directly dependent on the sperm stock acquired by females during copulation. In the lab, heat temperature treatments (32-44°C) were applied for 3 days in the pupal stage of Anisopteromalus calandrae males, and development was completed at 30°C. Three different effects were observed depending on the temperature: mortality above 42°C, sterility of emerging males at 40°C, and sub-fertility at 38°C. This sub-fertility is characterized by a dramatic decrease in male sperm supplies, of up to 7% compared to control males. In the course of ageing, the sperm stock of sub-fertile males increases but never reaches the level of control males. Survival was significantly higher in control (30°C) males than those treated at 38°C. Male mating ability was similar whatever the treatment (control and 38°C), but females mated with 38°C-treated males stored 100 times less sperm on average than those mated with control males. The offspring sex ratio of females mated with 38°C-treated males was strongly male biased. The physiological mechanisms are as yet unknown. The relationship between temperature, sperm stock and sex ratio should be taken into account in the management of parasitoids for integrated pest management. Copyright © 2012 Elsevier Ltd. All rights reserved.

Female choice in the red mason bee, Osmia rufa (L.) (Megachilidae).

PubMed

Conrad, Taina; Paxton, Robert J; Barth, Friedrich G; Francke, Wittko; Ayasse, Manfred

2010-12-01

Females are often thought to use several cues and more than one modality in selection of a mate, possibly because they offer complementary information on a mate's suitability. In the red mason bee, Osmia rufa, we investigated the criteria a female uses to choose a mating partner. We hypothesized that the female uses male thorax vibrations and size as signs of male viability and male odor for kin discrimination and assessment of genetic relatedness. We therefore compared males that had been accepted by a female for copulation with those rejected, in terms of their size, their immediate precopulatory vibrations (using laser vibrometry), the genetic relatedness of unmated and mated pairs (using microsatellite markers) and emitted volatiles (using chemical analyses). Females showed a preference for intermediate-sized males that were slightly larger than the modal male size. Furthermore, male precopulatory vibration burst duration was significantly longer in males accepted for copulation compared with rejected males. Vibrations may indicate vigor and assure that males selected by females are metabolically active and healthy. Females preferentially copulated with males that were genetically more closely related, possibly to avoid outbreeding depression. Volatiles of the cuticular surface differed significantly between accepted and rejected males in the relative amounts of certain hydrocarbons, although the relationship between male odor and female preference was complex. Females may therefore also use differences in odor bouquet to select among males. Our investigations show that O. rufa females appear to use multiple cues in selecting a male. Future investigations are needed to demonstrate whether odor plays a role in kin recognition and how the multiple cues are integrated in mate choice by females.

Heightened aggression and winning contests increase corticosterone but decrease testosterone in male Australian water dragons.

PubMed

Baird, Troy A; Lovern, Matthew B; Shine, Richard

2014-07-01

Water dragons (Intellegama [Physignathus] lesueurii) are large (to >1m) agamid lizards from eastern Australia. Males are fiercely combative; holding a territory requires incessant displays and aggression against other males. If a dominant male is absent, injured or fatigued, another male soon takes over his territory. Our sampling of blood from free-ranging adult males showed that baseline levels of both testosterone and corticosterone were not related to a male's social tactic (territorial versus non-territorial), or his frequency of advertisement display, aggression, or courtship behavior. Even when we elicited intense aggression by non-territorial males (by temporarily removing territory owners), testosterone did not increase with the higher levels of aggression that ensued. Indeed, testosterone levels decreased in males that won contests. In contrast, male corticosterone levels increased with the heightened aggression during unsettled conditions, and were higher in males that won contests. High chronic male-male competition in this dense population may favor high testosterone levels in all adult males to facilitate advertisement and patrol activities required for territory maintenance (by dominant animals), and to maintain readiness for territory take-overs (in non-territorial animals). Corticosterone levels increased in response to intense aggression during socially unstable conditions, and were higher in contest winners than losers. A positive correlation between the two hormones during socially unstable conditions suggests that the high stress of contests decreased androgen production. The persistent intense competition in this population appears to exact a high physiological cost, which together with our observation that males sometimes lose their territories to challengers may indicate cycling between these two tactics to manage long-term energetic costs. Copyright © 2014 Elsevier Inc. All rights reserved.

The impact of Wolbachia, male age and mating history on cytoplasmic incompatibility and sperm transfer in Drosophila simulans.

PubMed

Awrahman, Z A; Champion de Crespigny, F; Wedell, N

2014-01-01

Most insects harbour a variety of maternally inherited endosymbionts, the most widespread being Wolbachia pipientis that commonly induce cytoplasmic incompatibility (CI) and reduced hatching success in crosses between infected males and uninfected females. High temperature and increasing male age are known to reduce the level of CI in a variety of insects. In Drosophila simulans, infected males have been shown to mate at a higher rate than uninfected males. By examining the impact of mating rate independent of age, this study investigates whether a high mating rate confers an advantage to infected males through restoring their compatibility with uninfected females over and above the effect of age. The impact of Wolbachia infection, male mating rate and age on the number of sperm transferred to females during copulation and how it relates to CI expression was also assessed. As predicted, we found that reproductive compatibility was restored faster in males that mate at higher rate than that of low mating and virgin males, and that the effect of mating history was over and above the effect of male age. Nonvirgin infected males transferred fewer sperm than uninfected males during copulation, and mating at a high rate resulted in the transfer of fewer sperm per mating irrespective of infection status. These results indicate that the advantage to infected males of mating at a high rate is through restoration of reproductive compatibility with uninfected females, whereas uninfected males appear to trade off the number of sperm transferred per mating with female encounter rate and success in sperm competition. This study highlights the importance Wolbachia may play in sexual selection by affecting male reproductive strategies. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

The human operational sex ratio: effects of marriage, concealed ovulation, and menopause on mate competition.

PubMed

Marlowe, Frank W; Berbesque, J Colette

2012-12-01

Among mammals, male-male competition for sexual access to females frequently involves fighting. Larger body size gives males an advantage in fighting, which explains why males tend to be larger than females in many species, including anthropoid primates. Mitani et al. derived a formula to measure the operational sex ratio (OSR) to reflect the degree of male-male competition using the number of reproductively available males to females who are cycling and capable of conceiving. The OSR should predict the degree of sexual dimorphism in body mass-at least if male-male competition involves much fighting or threatening. Here, we use hunter-gatherer demographic data and the Mitani et al. formula to calculate the human OSR. We show that humans have a much lower degree of body mass sexual dimorphism than is predicted by our OSR. We suggest this is because human competition rarely involves fighting. In human hunter-gatherer societies, differences in the ages of marriage have an impact on competition in that the age of males at first marriage is younger when there is a lower percentage of married men with two or more wives, and older when there is a higher percentage of married men with two or more wives. We discuss the implications of this for females, along with the effects of two key life history traits that influence the OSR, concealed ovulation and menopause. While menopause decreases the number of reproductively available females to males and thus increases male-male competition, concealed ovulation decreases male-male competition. Finally, we discuss the importance of mostly monogamous mate bonds in human evolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Effect of Virus-Blocking Wolbachia on Male Competitiveness of the Dengue Vector Mosquito, Aedes aegypti

PubMed Central

Segoli, Michal; Hoffmann, Ary A.; Lloyd, Jane; Omodei, Gavin J.; Ritchie, Scott A.

2014-01-01

Background The bacterial endosymbiont Wolbachia blocks the transmission of dengue virus by its vector mosquito Aedes aegypti, and is currently being evaluated for control of dengue outbreaks. Wolbachia induces cytoplasmic incompatibility (CI) that results in the developmental failure of offspring in the cross between Wolbachia-infected males and uninfected females. This increases the relative success of infected females in the population, thereby enhancing the spread of the beneficial bacterium. However, Wolbachia spread via CI will only be feasible if infected males are sufficiently competitive in obtaining a mate under field conditions. We tested the effect of Wolbachia on the competitiveness of A. aegypti males under semi-field conditions. Methodology/Principal Findings In a series of experiments we exposed uninfected females to Wolbachia-infected and uninfected males simultaneously. We scored the competitiveness of infected males according to the proportion of females producing non-viable eggs due to incompatibility. We found that infected males were equally successful to uninfected males in securing a mate within experimental tents and semi-field cages. This was true for males infected by the benign wMel Wolbachia strain, but also for males infected by the virulent wMelPop (popcorn) strain. By manipulating male size we found that larger males had a higher success than smaller underfed males in the semi-field cages, regardless of their infection status. Conclusions/Significance The results indicate that Wolbachia infection does not reduce the competitiveness of A. aegypti males. Moreover, the body size effect suggests a potential advantage for lab-reared Wolbachia-males during a field release episode, due to their better nutrition and larger size. This may promote Wolbachia spread via CI in wild mosquito populations and underscores its potential use for disease control. PMID:25502564

The effect of virus-blocking Wolbachia on male competitiveness of the dengue vector mosquito, Aedes aegypti.

PubMed

Segoli, Michal; Hoffmann, Ary A; Lloyd, Jane; Omodei, Gavin J; Ritchie, Scott A

2014-12-01

The bacterial endosymbiont Wolbachia blocks the transmission of dengue virus by its vector mosquito Aedes aegypti, and is currently being evaluated for control of dengue outbreaks. Wolbachia induces cytoplasmic incompatibility (CI) that results in the developmental failure of offspring in the cross between Wolbachia-infected males and uninfected females. This increases the relative success of infected females in the population, thereby enhancing the spread of the beneficial bacterium. However, Wolbachia spread via CI will only be feasible if infected males are sufficiently competitive in obtaining a mate under field conditions. We tested the effect of Wolbachia on the competitiveness of A. aegypti males under semi-field conditions. In a series of experiments we exposed uninfected females to Wolbachia-infected and uninfected males simultaneously. We scored the competitiveness of infected males according to the proportion of females producing non-viable eggs due to incompatibility. We found that infected males were equally successful to uninfected males in securing a mate within experimental tents and semi-field cages. This was true for males infected by the benign wMel Wolbachia strain, but also for males infected by the virulent wMelPop (popcorn) strain. By manipulating male size we found that larger males had a higher success than smaller underfed males in the semi-field cages, regardless of their infection status. The results indicate that Wolbachia infection does not reduce the competitiveness of A. aegypti males. Moreover, the body size effect suggests a potential advantage for lab-reared Wolbachia-males during a field release episode, due to their better nutrition and larger size. This may promote Wolbachia spread via CI in wild mosquito populations and underscores its potential use for disease control.

Male Sling and Artificial Urethral Sphincter for Male Stress Urinary Incontinence Among Certifying American Urologists.

PubMed

Liu, Joceline S; Hofer, Matthias D; Milose, Jaclyn; Oberlin, Daniel T; Flury, Sarah C; Morey, Allen F; Gonzalez, Chris M

2016-01-01

To examine case volume characteristics among certifying urologists performing male sling and artificial urinary sphincter (AUS) procedures to evaluate practice patterns in male stress urinary incontinence (SUI). Six-month case log data of certifying urologists (2003-2013) were obtained from the American Board of Urology. Cases specifying Current Procedural Terminology code for male sling, AUS, and removal or revision of either procedure in males ≥18 years were analyzed. Among 1615 urologists (568 certifying and 1047 recertifying) logging at least 1 male incontinence procedure, 2109 (48% of all procedures) male sling and 2284 (52%) AUS cases were identified. The mean age of patients undergoing AUS was 74.9 years and the mean age of patients undergoing sling procedures was 67.3 years (P <.001). An increase in male incontinence procedures from 2003 to 2013 was demonstrated. The rate of male sling procedure increased from 32.7% of incontinence surgeries in 2004 to 45.5% in 2013 (P <.001). Academically affiliated urologists are 1.5 times more likely to perform AUS than male sling for SUI (P <.001). Median number of slings performed was 2 (range 1-40), with 32.7% placing slings exclusively. A small group of certifying urologists (3.4%) accounted for 22% of all male slings placed. This same cohort logged 10.2% of all AUS performed. Surgical management of male SUI varies widely across states (P <.001), with slings performed between 21% and 70% of the time. Overall the number of male incontinence procedures has increased over time, with a growing proportion of male slings. Most slings and AUS cases are performed by a small number of high-volume surgeons. Copyright © 2015 Elsevier Inc. All rights reserved.

Female Mimicry by Sneaker Males Has a Transcriptomic Signature in Both the Brain and the Gonad in a Sex-Changing Fish.

PubMed

Todd, Erica V; Liu, Hui; Lamm, Melissa S; Thomas, Jodi T; Rutherford, Kim; Thompson, Kelly C; Godwin, John R; Gemmell, Neil J

2018-01-01

Phenotypic plasticity represents an elegant adaptive response of individuals to a change in their environment. Bluehead wrasses (Thalassoma bifasciatum) exhibit astonishing sexual plasticity, including female-to-male sex change and discrete male morphs that differ strikingly in behavior, morphology, and gonadal investment. Using RNA-seq transcriptome profiling, we examined the genes and physiological pathways underlying flexible behavioral and gonadal differences among female, dominant (bourgeois) male, and female-mimic (sneaker) male blueheads. For the first time in any organism, we find that female mimicry by sneaker males has a transcriptional signature in both the brain and the gonad. Sneaker males shared striking similarity in neural gene expression with females, supporting the idea that males with alternative reproductive phenotypes have "female-like brains." Sneaker males also overexpressed neuroplasticity genes, suggesting that their opportunistic reproductive strategy requires a heightened capacity for neuroplasticity. Bourgeois males overexpressed genes associated with socio-sexual behaviors (e.g., isotocin), but also neuroprotective genes and biomarkers of oxidative stress and aging, indicating a hitherto unexplored cost to these males of attaining the reproductively privileged position at the top of the social hierarchy. Our novel comparison of testicular transcriptomes in a fish with male sexual polymorphism associates greater gonadal investment by sneaker males with overexpression of genes involved in cell proliferation and sperm quality control. We propose that morphological female-mimicry by sneaker male teleosts entails pervasive downregulation of androgenesis genes, consistent with low androgen production in males lacking well-developed secondary sexual characters. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A new public health context to understand male sex work.

PubMed

Minichiello, Victor; Scott, John; Callander, Denton

2015-03-24

Researching male sex work offers insight into the sexual lives of men and women while developing a more realistic appreciation for the changing issues associated with male sex work. This type of research is important because it not only reflects a growing and diversifying consumer demand for male sex work, but also because it enables the construction of knowledge that is up-to-date with changing ideas around sex and sexualities. This paper discusses a range of issues emerging in the male sex industry. Notably, globalisation and technology have contributed to the normalisation of male sex work and reshaped the landscape in which the male sex industry operates. As part of this discussion, we review STI and HIV rates among male sex workers at a global level, which are widely disparate and geographically contextual, with rates of HIV among male sex workers ranging from 0% in some areas to 50% in others. The Internet has reshaped the way that male sex workers and clients connect and has been identified as a useful space for safer sex messages and research that seeks out hidden or commonly excluded populations. We argue for a public health context that recognises the emerging and changing nature of male sex work, which means programs and policies that are appropriate for this population group. Online communities relating to male sex work are important avenues for safer sexual messages and unique opportunities to reach often excluded sub-populations of both clients and male sex workers. The changing structure and organisation of male sex work alongside rapidly changing cultural, academic and medical discourses provide new insight but also new challenges to how we conceive the sexualities of men and male sex workers. Public health initiatives must reflect upon and incorporate this knowledge.

A change in competitive context reverses sexual selection on male size.

PubMed

Kasumovic, M M; Andrade, M C B

2009-02-01

In studies of sexual selection, larger size is often argued to increase male fitness, and relatively smaller males are explained by genetic and/or environmental variation. We demonstrate that a size-development life-history trade-off could underlie the maintenance of a broad, unimodal distribution of size in male redback spiders (Latrodectus hasselti). Larger males are superior in direct competition, but redback males mature rapidly at small size in the presence of females. In field enclosures, we simulated two competitive contexts favouring development of divergent male sizes. Relatively smaller males lost when competing directly, but had 10 times higher fitness than relatively larger males when given the temporal advantage of rapid development. Linear selection gradients confirmed the reversal of selection on size, showing that it is critical to consider life-history decisions underlying the development of traits related to fitness.

Discovery and identification of a male-killing agent in the Japanese ladybird Propylea japonica (Coleoptera: Coccinellidae)

PubMed Central

2010-01-01

Background Endosymbionts that manipulate the reproduction of their hosts have been reported widely in invertebrates. One such group of endosymbionts is the male-killers. To date all male-killers reported are bacterial in nature, but comprise a diverse group. Ladybirds have been described as a model system for the study of male-killing, which has been reported in multiple species from widespread geographic locations. Whilst criteria of low egg hatch-rate and female-biased progenic sex ratio have been used to identify female hosts of male-killers, variation in vertical transmission efficiency and host genetic factors may result in variation in these phenotypic indicators of male-killer presence. Molecular identification of bacteria and screening for bacterial presence provide us with a more accurate method than breeding data alone to link the presence of the bacteria to the male-killing phenotype. In addition, by identifying the bacteria responsible we may find evidence for horizontal transfer between endosymbiont hosts and can gain insight into the evolutionary origins of male-killing. Phylogenetic placement of male-killing bacteria will allow us to address the question of whether male-killing is a potential strategy for only some, or all, maternally inherited bacteria. Together, phenotypic and molecular characterisation of male-killers will allow a deeper insight into the interactions between host and endosymbiont, which ultimately may lead to an understanding of how male-killers identify and kill male-hosts. Results A male-killer was detected in the Japanese coccinellid, Propylea japonica (Thunberg) a species not previously known to harbour male-killers. Families produced by female P. japonica showed significantly female-biased sex ratios. One female produced only daughters. This male-killer trait was maternally inherited and antibiotic treatment produced a full, heritable cure. Molecular analysis identified Rickettsia to be associated with the trait in this species of ladybird. Conclusion We conclude that P. japonica is host to a bacterial male-killer that is vertically inherited with variable transmission efficiency. Rickettsia presence correlates with the male-killing trait, but there is some variation in the phenotypic expression of the trait due to interaction with host factors. Phylogenetic analysis using the 16S rRNA and 17 kDa antigen genes suggests there may have been horizontal transfer of Rickettsial male-killers between different ladybird hosts. PMID:20149223

Do knowledge and cultural perceptions of modern female contraceptives predict male involvement in Ayete, Nigeria?

PubMed

Sanusi, A; Akinyemi, Oluwaseun O; Onoviran, Oghemetega O

2014-12-01

Male involvement is crucial to female contraceptive use. This study examined how male knowledge and cultural perceptions of modern female contraceptives influence involvement in contraceptive use. A cross-sectional survey of 389 men from Ayete, Nigeria was used to regress a continuous male involvement score on demographic variables, knowledge of at least one method of modern female contraception and a scored male perception variable using Ordinary Least Squares regression. Controlling for perception, the knowledge of at least one method of modern female contraception was not significantly associated with a change in male involvement (p=0.264). Increasing positive perception was associated with higher male involvement scores (p=0.001). Higher educated males, those with a current desire to have children and males whose partners were currently using a method had greater male involvement scores (p<0.05). Policy and intervention efforts should be focused on changing cultural perceptions, in addition to providing in-depth knowledge of contraceptive methods.

Asymmetries in Infants’ Attention Toward and Categorization of Male Faces: The Potential Role of Experience

PubMed Central

Rennels, Jennifer L.; Kayl, Andrea J.; Langlois, Judith H.; Davis, Rachel E.; Orlewicz, Mateusz

2015-01-01

Infants typically have a preponderance of experience with females, resulting in visual preferences for female faces, particularly high attractive females, and in better categorization of female relative to male faces. We examined whether these abilities generalized to infants’ visual preferences for and categorization of perceptually similar male faces (i.e., low masculine males). Twelve-month-olds visually preferred high attractive relative to low attractive male faces within low masculine pairs only (Exp. 1), but did not visually prefer low masculine relative to high masculine male faces (Exp. 2). Lack of visual preferences was not due to infants’ inability to discriminate between the male faces (Exps. 3 & 4). Twelve-month-olds categorized low masculine, but not high masculine, male faces (Exp. 5). Infants could individuate male faces within each of the categories (Exp. 6). Twelve-month-olds’ attention toward and categorization of male faces may reflect a generalization of their female facial expertise. PMID:26547249

Sexual selection of male parental care in giant water bugs

PubMed Central

Ohba, Shin-ya; Okuda, Noboru; Kudo, Shin-ichi

2016-01-01

Paternal care can be maintained under sexual selection, if it helps in attracting more mates. We tested the hypothesis in two giant water bug species, Appasus major and Appasus japonicus, that male parental care is sexually selected through female preference for caring males. Females were given an opportunity to choose between two males. In the first test of female mate choice, one male carried eggs on its back, while the other did not. The egg status was switched between these two males in the second test. The experiment revealed that females of both species preferred caring males (i.e. egg-bearing) to non-caring males. Nonetheless, the female mate preference for egg-bearing males was stronger in A. major than in A. japonicus. Our results suggest that sexual selection plays an important role in maintaining elaborate paternal care in giant water bugs, but the importance of egg-bearing by males in female mate choice varies among species. PMID:27293778

Male adaptations to minimize sexual cannibalism during reproduction in the funnel-web spider Hololena curta.

PubMed

Xiao, Yong-Hong; Zunic-Kosi, Alenka; Zhang, Long-Wa; Prentice, Thomas R; McElfresh, J Steven; Chinta, Satya P; Zou, Yun-Fan; Millar, Jocelyn G

2015-12-01

Males of many spider species risk being attacked and cannibalized while searching for, courting, and mating with conspecific females. However, there are exceptions. We show that the funnel-web spider, Hololena curta, has 3 adaptations that minimize risk to males during courtship and mating, and enhance reproductive success. First, males detected chemical or tactile signals associated with webs of virgin females, and differentiated them from webs of mated females, enabling males to increase encounter rates with virgin females and avoid aggressive mated females. Second, males produced stereotyped vibrational signals during courting which induced female quiescence and suppressed female aggression. Third, when touched by males, sexually receptive females entered a cataleptic state, allowing males to safely approach and copulate. Because males can mate multiple times and the sex ratio in natural populations of H. curta is female biased, overall reproductive output is likely increased by males of this species avoiding sexual cannibalism. © 2015 Institute of Zoology, Chinese Academy of Sciences.

High power connection system

DOEpatents

Schaefer, Christopher E.; Beer, Robert C.; McCall, Mark D.

2000-01-01

A high power connection system adapted for automotive environments which provides environmental and EMI shielding includes a female connector, a male connector, and a panel mount. The female connector includes a female connector base and a snap fitted female connector cover. The male connector includes a male connector base and a snap fitted male connector cover. The female connector base has at least one female power terminal cavity for seatably receiving a respective female power terminal. The male connector base has at least one male power terminal cavity for seatably receiving a respective male power terminal. The female connector is covered by a cover seal and a conductive shroud. A pair of lock arms protrude outward from the front end of the male connector base, pass through the panel mount and interface with a lever of a lever rotatably connected to the shroud to thereby mechanically assist mating of the male and female connectors. Safety terminals in the male and female connectors provide a last-to-connect-first-to-break connection with an HVIL circuit.

Heterosexual Men's Anger in Response to Male Homosexuality: Effects of Erotic and Non-Erotic Depictions of Male-Male Intimacy and Sexual Prejudice

PubMed Central

Hudepohl, Adam D.; Parrott, Dominic J.; Zeichner, Amos

2010-01-01

The present study compared effects of erotic and non-erotic depictions of male-male intimacy on the experience of anger in heterosexual men. Data came from three independent laboratory studies designed to elicit anger in response to erotic or non-erotic depictions of male-male and male-female intimacy. All participants completed a measure of sexual prejudice and anger was assessed before and after viewing the erotic or non-erotic video. Among high-prejudiced men, viewing erotic and non-erotic intimate behavior between two men elicited significant increases in anger relative to viewing comparable behavior between a male-female dyad. In contrast, among low-prejudiced men, viewing erotic, but not non-erotic, intimate behavior between two men elicited significant increases in anger relative to viewing comparable behavior between a male-female dyad. Implications for understanding heterosexual men's anger, and aggression, toward gay men were discussed. PMID:20818528

Home ranges and satellite tactics of male green swordtails (Xiphophorus helleri) in nature.

PubMed

Franck, D; Klamroth, B; Taebel-Hellwig, A; Schartl, M

1998-05-01

Dominance relationships were studied between marked or otherwise individually recognizable male green swordtails in a creek at Lake Catemaco and in a tributary of the Rio Atoyac (Veracruz, Mexico). The Atoyac population is unique because of a high degree of polymorphism, including both macromelanophore spotting and a micromelanophore tailspot pattern. During the dry season males living in the same area maintained a linear social hierarchy for periods of many days. The subordinate males settled down either in the same home ranges or in home ranges largely overlapping with that of dominant males. Although dominant males untiringly chased the subordinate males away, they returned persistently and achieved the status of non-tolerated satellites. Females were less stationary and presumably passed through many male home ranges during their feeding activities. The data clearly demonstrate that green swordtails live in complex social systems in which male-male competition and probably also female mate choice are likely to be essential factors for individual reproductive success.

Boar taint, meat quality and fail rate in entire male pigs and male pigs immunized against gonadotrophin releasing factor as related to body weight and feeding regime.

PubMed

Moore, K L; Mullan, B P; Dunshea, F R

2017-03-01

The objective of this experiment was to compare the pork quality of entire male pigs and pigs immunized against GnRF (IC males) at both light (64.8kg) and heavy (106kg) liveweights and two feeding regimes (restricted at 2.5 times maintenance and ad libitum). There was no difference in objective measurements (P>0.05) or eating pork quality (P>0.1) between entire male and IC males. Fail rates were reduced by 9.1% and 12% for pork from IC males for quality grade (P=0.007) and re-purchase intention (P=0.001), respectively, compared to pork from entire males. Skatole (P=0.001) and androstenone (P<0.001) levels in belly fat were higher in entire male than IC male pigs. In addition, 37.5% of the light entire male pigs fed ad libitum showed skatole levels that exceeded the sensory threshold of 0.2μg/g. This work confirms that immunization against GnRF is effective in eliminating boar taint and reducing pork quality fail rates by approximately 10% compared to pork from entire males. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Role of Bioacoustic Signals in Koala Sexual Selection: Insights from Seasonal Patterns of Associations Revealed with GPS-Proximity Units.

PubMed

Ellis, William; FitzGibbon, Sean; Pye, Geoff; Whipple, Bill; Barth, Ben; Johnston, Stephen; Seddon, Jenny; Melzer, Alistair; Higgins, Damien; Bercovitch, Fred

2015-01-01

Despite being a charismatic and well-known species, the social system of the koala (Phascolarctos cinereus--the only extant member of the family Phascolarctidae) is poorly known and much of the koala's sociality and mating behaviors remain un-quantified. We evaluated these using proximity logging-GPS enabled tracking collars on wild koalas and discuss their implications for the mating system of this species. The frequency and duration of male-female encounters increased during the breeding season, with male-male encounters quite uncommon, suggesting little direct mating competition. By comparison, female-female interactions were very common across both seasons. Body mass of males was not correlated with their interactions with females during the breeding season, although male size is associated with a variety of acoustic parameters indicating individuality. We hypothesise that vocal advertising reduces the likelihood of male-male encounters in the breeding season while increasing the rate of male-female encounters. We suggest that male mating-season bellows function to reduce physical confrontations with other males allowing them to space themselves apart, while, at the same time, attracting females. We conclude that indirect male-male competition, female mate choice, and possibly female competition, mediate sexual selection in koalas.

Social organization of sea otters in Prince William Sound, Alaska

USGS Publications Warehouse

Garshelis, David L.; Johnson, Ancel M.; Garshelis, Judith A.

1984-01-01

Sea otters in Prince William Sound. Alaska, were spatially segregated into predominantly (97%) male areas at the front of the expanding population and breeding areas with fewer (up to 33%) males. From 1975 to 1984 we captured and marked 267 otters with tags and (or) radio transmitters and investigated their reproductive strategies, social relationships, and patterns of sexual segregation. Mating occurred year-round, but peaked in September and October. Females first bred at 4 years of age and were capable of pupping annually; they generally separated from their pup before mating. Males established breeding territories that enabled prolonged precopulatory interactions that may have prompted female–pup separation and post-copulatory interactions that precluded females from mating with other males. Male mating success was related to age, weight, territory quality, and the length of time they maintained their territory. After the breeding season, territorial males returned to male areas where food was more abundant. Young, dispersing males also entered male areas and remained there until attaining breeding age. In male areas, otters commonly rested in groups of >50 individuals. Gregariousness promoted social interactions and likely enhanced food finding and (historically) predator protection. As food diminished, males moved into adjacent, unoccupied regions; females then occupied former male areas.

Mothers matter! Maternal support, dominance status and mating success in male bonobos (Pan paniscus)

PubMed Central

Surbeck, Martin; Mundry, Roger; Hohmann, Gottfried

2011-01-01

Variation in male mating success is often related to rank differences. Males who are unable to monopolize oestrous females alone may engage in coalitions, thus enhancing their mating success. While studies on chimpanzees and dolphins suggest that coalitions are independent of kinship, information from female philopatric species shows the importance of kin support, especially from mothers, on the reproductive success of females. Therefore, one might expect a similar effect on sons in male philopatric species. We evaluate mating success determinants in male bonobos using data from nine male individuals from a wild population. Results reveal a steep, linear male dominance hierarchy and a positive correlation between dominance status and mating success. In addition to rank, the presence of mothers enhances the mating success of sons and reduces the proportion of matings by the highest ranking male. Mothers and sons have high association rates and mothers provide agonistic aid to sons in conflicts with other males. As bonobos are male-philopatric and adult females occupy high dominance status, maternal support extends into adulthood and females have the leverage to intervene in male conflicts. The absence of female support to unrelated males suggests that mothers gain indirect fitness benefits by supporting their sons. PMID:20810444

Paternity and Dominance Loss in Male Breeders: The Cost of Helpers in a Cooperatively Breeding Mammal

PubMed Central

Lardy, Sophie; Cohas, Aurélie; Desouhant, Emmanuel; Tafani, Marion; Allainé, Dominique

2012-01-01

Paternity insurance and dominance tenure length are two important components of male reproductive success, particularly in species where reproduction is highly skewed towards a few individuals. Identifying the factors affecting these two components is crucial to better understand the pattern of variation in reproductive success among males. In social species, the social context (i.e. group size and composition) is likely to influence the ability of males to secure dominance and to monopolize reproduction. Most studies have analyzed the factors affecting paternity insurance and dominance tenure separately. We use a long term data set on Alpine marmots to investigate the effect of the number of subordinate males on both paternity insurance and tenure of dominant males. We show that individuals which are unable to monopolize reproduction in their family groups in the presence of many subordinate males are likely to lose dominance the following year. We also report that dominant males lose body mass in the year they lose both paternity and dominance. Our results suggest that controlling many subordinate males is energetically costly for dominant males, and those unable to support this cost lose the control over both reproduction and dominance. A large number of subordinate males in social groups is therefore costly for dominant males in terms of fitness. PMID:22272236

Male-Biased Sexual Size Dimorphism, Resource Defense Polygyny, and Multiple Paternity in the Emei Moustache Toad (Leptobrachium boringii)

PubMed Central

Hudson, Cameron M.; Fu, Jinzhong

2013-01-01

We tested the hypotheses that the Emei moustache toad (Leptobrachium boringii) exhibits resource defense polygyny and that combat led to the evolution of male-biased sexual size dimorphism. Between February and March of 2011 and 2012, 26 female and 55 male L. boringii from Mount Emei UNESCO World Heritage Site, Sichuan, China, were observed throughout the breeding season. Prior to the breeding season, males grow 10–16 keratinized maxillary nuptial spines, which fall off once the season has ended. Throughout this time, males construct and defend aquatic nests where they produce advertisement calls to attract females. In a natural setting, we documented 14 cases involving a total of 22 males where males used their moustaches for aggressive interaction, and nest takeover was observed on seven occasions. Males were also observed to possess injuries resulting from combat. Genetic analysis using microsatellite DNA markers revealed several cases of multiple paternity, both within nest and within clutch. This observation indicated that some alternative male reproductive strategy, such as satellite behaviour, is occurring, which may have led to the multiple paternity. Larger males were observed to mate more frequently, and in multiple nests, suggesting that females are selecting for larger males, or that larger males are more capable of defending high quality territories. PMID:23840725

The effects of food limitation on life history tradeoffs in pregnant male gulf pipefish.

PubMed

Paczolt, Kimberly A; Jones, Adam G

2015-01-01

Syngnathid fishes (pipefishes, seahorses and seadragons) are characterized by a unique mode of paternal care in which embryos develop on or in the male's body, often within a structure known as a brood pouch. Evidence suggests that this pouch plays a role in mediating postcopulatory sexual selection and that males have some control over the events occurring within the pouch during the pregnancy. These observations lead to the prediction that males should invest differently in broods depending on the availability of food. Here, we use the Gulf pipefish to test this prediction by monitoring growth rate and offspring survivorship during the pregnancies of males under low- or high-food conditions. Our results show that pregnant males grow less rapidly on average than non-pregnant males, and pregnant males under low-food conditions grow less than pregnant males under high-food conditions. Offspring survivorship, on the other hand, does not differ between food treatments, suggesting that male Gulf pipefish sacrifice investment in somatic growth, and thus indirectly sacrifice future reproduction, in favor of current reproduction. However, a positive relationship between number of failed eggs and male growth rate in our low-food treatments suggests that undeveloped eggs reduce the pregnancy's overall cost to the male compared to broods containing only viable offspring.

Sperm traits differ between winged and wingless males of the ant Cardiocondyla obscurior.

PubMed

Schrempf, Alexandra; Moser, Astrid; Delabie, Jacques; Heinze, Jürgen

2016-11-01

Size and shape of sperm cells vary tremendously throughout the animal kingdom. The adaptive significance of this variation is not fully understood. In addition to sperm-female interactions and the environmental conditions, the risk of sperm competition might affect number, morphology and other "quality" traits of sperm. In the male-diphenic ant Cardiocondyla obscurior, winged sneaker males have limited sperm number, because their testes degenerate shortly after adult emergence, as is typical for males of social Hymenoptera. In contrast, wingless fighter males continuously replenish their sperm supply due to their exceptional lifelong spermatogenesis. While winged males usually have to compete with several other winged males for virgin queens, wingless males are able to monopolize queens by killing all other rivals. Hence, this presents a unique system to investigate how alternative reproductive tactics and associated physiology affect sperm morphology and viability. We found that sperm-limited males invest into sperm number instead of sperm size. Variance in sperm length is smaller in winged males, probably reflecting that they have to compete with several other males. Finally, sperm viability is equally high in both male phenotypes. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Sex differences in autism: a resting-state fMRI investigation of functional brain connectivity in males and females

PubMed Central

Swinnen, Stephan P.; Wenderoth, Nicole

2016-01-01

Autism spectrum disorders (ASD) are far more prevalent in males than in females. Little is known however about the differential neural expression of ASD in males and females. We used a resting-state fMRI-dataset comprising 42 males/42 females with ASD and 75 male/75 female typical-controls to examine whether autism-related alterations in intrinsic functional connectivity are similar or different in males and females, and particularly whether alterations reflect ‘neural masculinization’, as predicted by the Extreme Male Brain theory. Males and females showed a differential neural expression of ASD, characterized by highly consistent patterns of hypo-connectivity in males with ASD (compared to typical males), and hyper-connectivity in females with ASD (compared to typical females). Interestingly, patterns of hyper-connectivity in females with ASD reflected a shift towards the (high) connectivity levels seen in typical males (neural masculinization), whereas patterns of hypo-connectivity observed in males with ASD reflected a shift towards the (low) typical feminine connectivity patterns (neural feminization). Our data support the notion that ASD is a disorder of sexual differentiation rather than a disorder characterized by masculinization in both genders. Future work is needed to identify underlying factors such as sex hormonal alterations that drive these sex-specific neural expressions of ASD. PMID:26989195

Sex Allocation and Reproductive Success in the Andromonoecious Perennial Solanum carolinense (Solanaceae). II. Paternity and Functional Gender.

PubMed

Elle, Elizabeth; Meagher, Thomas R

2000-12-01

According to Bateman's principle, male fitness in entomophilous plant species should be limited by mating opportunity, which is influenced by the size or number of flowers. We determined male-specific fitness consequences of floral phenotype in andromonoecious Solanum carolinense, examined the relationship between male and female reproductive success within plants, and evaluated the distribution of functional gender among plants. A maximum likelihood-based paternity analysis, based on multilocus allozyme phenotypes of parents and offspring from four experimental plots, was used to determine male reproductive success and its relationship to floral phenotype. Male success was enhanced by an increase in the proportion of male flowers produced but not by an increase in total flower number, even though all flowers contain male parts. Larger flower size increased male success in only one plot. Male and female reproductive success were negatively correlated, and plants varied in functional gender from completely female to completely male. This gender specialization may occur because hermaphroditic and male flowers differ in their ability to contribute to male and female success. Although sex allocation theory predicts a positive relationship between the size or number of plant parts and reproductive success, this study indicates that aspects of floral morphology that affect gender specialization should also be considered.

Triadic awareness predicts partner choice in male-infant-male interactions in Barbary macaques.

PubMed

Kubenova, Barbora; Konecna, Martina; Majolo, Bonaventura; Smilauer, Petr; Ostner, Julia; Schülke, Oliver

2017-03-01

Social knowledge beyond one's direct relationships is a key in successfully manoeuvring the social world. Individuals gather information on the quality of social relationships between their group companions, which has been termed triadic awareness. Evidence of the use of triadic awareness in natural contexts is limited mainly to conflict management. Here we investigated triadic awareness in wild Barbary macaques (Macaca sylvanus) in the context of bridging interactions defined as male-infant-male interactions whereby a male (initiator, holder) presents an infant to another male (receiver, non-holder) in order to initiate an affiliative interaction with that male. Analyses based on 1263 h of focal observations on ten infants of one wild social group in Morocco supported the hypothesis that males use their knowledge of the relationship between infants and other adult males when choosing a male as a partner for bridging interactions. Specifically, (i) the number of bridging interactions among holder-infant-receiver triads was positively affected by the strength of the infant-receiver relationship and (ii) when two males were available as bridging partners, a male was more likely to be chosen as the receiver the stronger his social relationship with the infant relative to the other available male. This demonstrates that non-human primates establish triadic awareness of temporary infant-male relationships and use it in a naturally occurring affiliative context. Our results contribute to the discussion about the mechanism underlying the acquisition of triadic awareness and the benefits of its usage, and lend support to hypotheses linking social complexity to the evolution of complex cognition.

Modification of Male Courtship Motivation by Olfactory Habituation via the GABAA Receptor in Drosophila melanogaster

PubMed Central

Tachibana, Shin-Ichiro; Touhara, Kazushige; Ejima, Aki

2015-01-01

A male-specific component, 11-cis-vaccenyl acetate (cVA) works as an anti-aphrodisiac pheromone in Drosophila melanogaster. The presence of cVA on a male suppresses the courtship motivation of other males and contributes to suppression of male-male homosexual courtship, while the absence of cVA on a female stimulates the sexual motivation of nearby males and enhances the male-female interaction. However, little is known how a male distinguishes the presence or absence of cVA on a target fly from either self-produced cVA or secondhand cVA from other males in the vicinity. In this study, we demonstrate that male flies have keen sensitivity to cVA; therefore, the presence of another male in the area reduces courtship toward a female. This reduced level of sexual motivation, however, could be overcome by pretest odor exposure via olfactory habituation to cVA. Real-time imaging of cVA-responsive sensory neurons using the neural activity sensor revealed that prolonged exposure to cVA decreased the levels of cVA responses in the primary olfactory center. Pharmacological and genetic screening revealed that signal transduction via GABAA receptors contributed to this olfactory habituation. We also found that the habituation experience increased the copulation success of wild-type males in a group. In contrast, transgenic males, in which GABA input in a small subset of local neurons was blocked by RNAi, failed to acquire the sexual advantage conferred by habituation. Thus, we illustrate a novel phenomenon in which olfactory habituation positively affects sexual capability in a competitive environment. PMID:26252206

Seminal fluid enhances competitiveness of territorial males' sperm in a fish with alternative male reproductive tactics.

PubMed

Poli, Federica; Locatello, Lisa; Rasotto, Maria B

2018-05-29

The most common adaptation to sperm competition in males is represented by an increase in the sperm number and/or quality released at mating, to raise their probability of egg fertilization. However, rapidly mounting evidence highlights that seminal fluid may directly influence the competitive fertilization success of a male by affecting either own and/or rival sperm performances. In the black goby, Gobius niger , an external fertilizer with guard-sneaker mating tactics and high sperm competition level, sneaker males' ejaculates contain less seminal fluid and more sperm, that are also of better quality, than those of territorial males. However, territorial males, gain a higher paternity success inside natural nests. Here, we ask whether the seminal fluid can contribute to territorial males' reproductive success by enhancing their sperm performances and/or by decreasing those of sneaker males. Using sperm and seminal fluid manipulation and in vitro fertilization tests, we found that own seminal fluid influences the velocity and fertilization ability of sperm only in territorial males, making them as faster as those of sneakers and with similar fertilization rate. Moreover, both sneaker and territorial males' sperm remain unaffected by the seminal fluid of rival males. Thus, black goby males respond to the different level of sperm competition faced by differently allocating in sperm and non-sperm components of the ejaculate, with sneakers primarily investing in sperm of intrinsic high quality and territorial males relying on the effect of seminal fluid to increase the lower intrinsic quality of their sperm. © 2018. Published by The Company of Biologists Ltd.

Multiple roles of a male-specific compound in the sexual behavior of the dried bean beetle, Acanthoscelides obtectus.

PubMed

Vuts, József; Powers, Stephen J; Caulfield, John C; Pickett, John A; Birkett, Michael A

2015-03-01

Males of Acanthoscelides obtectus (Coleoptera: Chrysomelidae, Bruchinae) emit methyl (E,R)-2,4,5-tetradecatrienoate that attracts females for mating. This study identified further roles for this compound in the sexual behavior of A. obtectus. Earlier observations revealed that males touched females with their antennae while tandem-running with them and initiated mounting and copulation, whereas they showed no such behavior toward other males. A series of subsequent laboratory choice tests were set up to establish if certain cuticular compounds aid contact sex recognition in A. obtectus. Males chose virgin females over other males. The activity toward females could be eliminated by rinsing with hexane, but was regained by application of female extract onto previously rinsed females. Gas chromatographic (GC) comparison of hexane extracts revealed the presence of two male-specific compounds, methyl (E,R)-2,4,5-tetradecatrienoate and octadecanal, which were absent from the behaviorally active female samples. Of the two compounds, methyl (E,R)-2,4,5-tetradecatrienoate was found to be responsible for the inhibition of male sexual behavior, similar to that observed with crude male extracts applied to virgin females. Furthermore, males preferred virgin over mated females. GC analyses revealed the presence of methyl (E,R)-2,4,5-tetradecatrienoate in mated females in amounts sufficient to curtail mating attempts. It appears that methyl (E,R)-2,4,5-tetradecatrienoate, besides being a male-produced sex pheromone, acts as a male-recognition signal in A. obtectus. Males also transfer it onto females during mating, resulting in mated females being avoided by courting males.

Investment in testes, sperm-duct glands and lipid reserves differs between male morphs but not between early and late breeding season in Pomatoschistus minutus.

PubMed

Kvarnemo, C; Svensson, O; Manson, W

2010-05-01

This study of the sand goby Pomatoschistus minutus, a nest-holding fish with paternal care, focused on gonadal investment among males of different sizes collected early and late in the breeding season. All males caught at the nest had breeding colour, whereas trawl-caught fish consisted of males both with and without colour. The absence or presence of breeding colour was a good predictor of testes investment. Compared to males with breeding colour, males without colour were smaller in body size but had extraordinarily large testes. In absolute terms, testes mass of males without breeding colour was on average 3.4 times greater than those of males with breeding colour. Since small colourless males are known to reproduce as sneaker males, this heavy investment in testes probably reflects that they are forced to spawn under sperm competition. Contrary to testes size, sperm-duct glands were largest among males with breeding colour. These glands produce mucins used for making sperm-containing mucous trails that males place in the nest before and during spawning. Since both sneakers and nest-holders potentially could benefit from having large glands, this result is intriguing. Yet, high mucus production may be more important for nest-holders, because it also protects developing embryos from infections. There was no significant effect of season on body size, testes or sperm-duct glands size, but colourless males tended to be less common late in the season. Possibly this may indicate that individual small colourless males develop into their more colourful counterparts within the breeding season.

Reproductive traits in captive and free-ranging males of the critically endangered Iberian lynx (Lynx pardinus).

PubMed

Gañán, Natalia; Sestelo, Adrián; Garde, J Julián; Martínez, Fernando; Vargas, Astrid; Sánchez, Iñigo; Pérez-Aspa, María José; López-Bao, José Vicente; Palomares, Francisco; Gomendio, Montserrat; Roldan, Eduardo R S

2010-01-01

The Iberian lynx (Lynx pardinus) is the most endangered felid in the world. Adequate genetic management of in situ and ex situ populations, and linkage between both, require knowledge on male reproductive biology and factors influencing it. We examined the influence of age, free-ranging versus captive conditions and seasonality on phenotypic, endocrine and semen traits, and links between reproductive traits and male fertility. Males had relatively small testes, produced low sperm numbers, a low proportion of normal sperm, and a high proportion of motile sperm. Young (2-year-old) males had lower testosterone levels, fewer sperm, and a lower proportion of motile and normal sperm than > or =4-year-old males. No major differences were found in semen traits before and after the mating season or between free-ranging and captive males, although the latter had better sperm motility. Males with larger relative testes weight and more sperm copulated more frequently, whereas males that produced more sperm with higher motility produced more cubs per female. In conclusion, small relative testes size and low sperm quality could indicate either low levels of sperm competition or high levels of inbreeding. Young males are probably subfertile; there is a slight trend for males in the captive breeding programme to have better semen quality than wild males, and males with higher sperm production are sexually more active and more fertile. These findings have major implications for decisions regarding which males should breed, provide samples for the genetic resource bank, or participate in programmes involving the use of assisted reproductive techniques.

Male urine signals social rank in the Mozambique tilapia (Oreochromis mossambicus)

PubMed Central

Barata, Eduardo N; Hubbard, Peter C; Almeida, Olinda G; Miranda, António; Canário, Adelino VM

2007-01-01

Background The urine of freshwater fish species investigated so far acts as a vehicle for reproductive pheromones affecting the behaviour and physiology of the opposite sex. However, the role of urinary pheromones in intra-sexual competition has received less attention. This is particularly relevant in lek-breeding species, such as the Mozambique tilapia (Oreochromis mossambicus), where males establish dominance hierarchies and there is the possibility for chemical communication in the modulation of aggression among males. To investigate whether males use urine during aggressive interactions, we measured urination frequency of dye-injected males during paired interactions between size-matched males. Furthermore, we assessed urinary volume stored in the bladder of males in a stable social hierarchy and the olfactory potency of their urine by recording of the electro-olfactogram. Results Males released urine in pulses of short duration (about one second) and markedly increased urination frequency during aggressive behaviour, but did not release urine whilst submissive. In the stable hierarchy, subordinate males stored less urine than males of higher social rank; the olfactory potency of the urine was positively correlated with the rank of the male donor. Conclusion Dominant males store urine and use it as a vehicle for odorants actively released during aggressive disputes. The olfactory potency of the urine is positively correlated with the social status of the male. We suggest that males actively advertise their dominant status through urinary odorants which may act as a 'dominance' pheromone to modulate aggression in rivals, thereby contributing to social stability within the lek. PMID:18076759

Conflict between background matching and social signalling in a colour-changing freshwater fish.

PubMed

Kelley, Jennifer L; Rodgers, Gwendolen M; Morrell, Lesley J

2016-06-01

The ability to change coloration allows animals to modify their patterning to suit a specific function. Many freshwater fishes, for example, can appear cryptic by altering the dispersion of melanin pigment in the skin to match the visual background. However, melanin-based pigments are also used to signal dominance among competing males; thus colour change for background matching may conflict with colour change for social status signalling. We used a colour-changing freshwater fish to investigate whether colour change for background matching influenced aggressive interactions between rival males. Subordinate males that had recently darkened their skin for background matching received heightened aggression from dominant males, relative to males whose coloration had not changed. We then determined whether the social status of a rival male, the focal male's previous social status, and his previous skin coloration, affected a male's ability to change colour for background matching. Social status influenced skin darkening in the first social encounter, with dominant males darkening more than subordinate males, but there was no effect of social status on colour change in the second social encounter. We also found that the extent of skin colour change (by both dominant and subordinate males) was dependent on previous skin coloration, with dark males displaying a smaller change in coloration than pale males. Our findings suggest that skin darkening for background matching imposes a significant social cost on subordinate males in terms of increased aggression. We also suggest that the use of melanin-based signals during social encounters can impede subsequent changes in skin coloration for other functions, such as skin darkening for background matching.

Differences in nutrient intakes and physical activity levels of Japanese and Australian Caucasian males living in Australia and Japanese males living in Japan.

PubMed

Kagawa, Masaharu; Saito, Yoko; Kerr, Deborah; Uchida, Hayato; Binns, Colin W

2006-01-01

The aim of the study was to determine the nutritional status and nutrient intakes of young Japanese males living in Australia and compared with Japanese males living in Japan and Australian Caucasian males. Four-day dietary records were obtained from 65 Japanese living in Australia (JA), 81 Japanese living in Japan (JJ), and 70 Australian Caucasian males (AA) aged 18-30 years old, together with body composition and physical activity level assessments using anthropometry and the questionnaire. Australian males were significantly taller and heavier than the Japanese counterparts and also showed a greater percent body fat (%BF) and height-corrected sum of skinfolds compared with Japanese males living in Japan (%BF: JJ = 16.6 +/- 5.2, AA = 18.7 +/- 5.6; height corrected sum of skinfolds: JJ = 78.8 +/- 37.3, AA = 96.0 +/- 39.5) (P<0.05). A greater proportion of Australian Caucasian males (98.6%) were involved in vigorous physical exercise than Japanese males (JA = 72.3%; JJ = 85.2%). The JA group consumed a greater amount of energy from protein and fat sources as well as greater calcium, iron, dietary fibre and niacin equivalents intakes than the JJ group (P<0.05). The results suggest that Japanese males living in Australia consumed more energy-dense westernised diet than Japanese males living in Japan. Because of lower physical activity level than Australian males, consumption of energy-dense diet may increase the risk of weight gain among Japanese males who stay in Australia for a long-term.

Sex steroid levels in XY males and sex-reversed XX males, of rainbow trout (Oncorhynchus mykiss), during the reproductive cycle.

PubMed

Espinosa, E; Josa, A; Gil, L; González, N

2011-02-01

In this study, the annual cycle of the gonadal steroids testosterone (T), 11-ketotestosterone (11-KT), 17β-oestradiol (E2) and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) was determined using radioimmunoassay and then compared, for XY males (n=35) and sex-reversed XX males (n=27) rainbow trout, to establish possible endocrinology differences. Both in XY males and sex-reversed XX males, significant correlation was shown between body weight and T (r=0.5046 and 0.34078, respectively; p<0.0001) or KT (r=0.52494 and 0.43545, respectively; p<0.0001) concentrations. Plasma androgen levels in XY and sex-reversed XX males were similar and showed an intense seasonal variation. The highest levels for T and 11-KT were detected from December to April with a peak in January (51.67 ± 5.11 and 61.95 ± 4.25 ng/ml, for XY males and 57.1 ± 5.82 and 59.27 ± 4.84 ng/ml, respectively, for XX males). In addition, there was a positive correlation (p<0.0001) between T and 11-KT levels for XY males (r=0.7533) and sex-reversed XX males (r=0.6019). Concentrations of DHP in XY males also showed seasonal variation with a peak in February (25.18 ± 12.99 ng/ml). However, DHP levels in sex-reversed XX males were undetectable (<0.1 ng/ml) over the year. Levels of E2 were undetectable through the year in both groups of trout. In conclusion, the androgenic and oestrogenic profiles of sex-reversed XX males were similar to those observed in XY males. The only difference in the annual gonadal steroid cycle between XY and sex-reversed XX males was in the DHP profile. © 2009 Blackwell Verlag GmbH.

Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens)

PubMed Central

Jensen, K. H.; Mayer, I.; Jakobsen, P. J.

2015-01-01

Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG) of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG) mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate availability and male—male competition. PMID:26642324

"Nice guys finish last": influence of mate choice on reproductive success in Long-Evans rats.

PubMed

Winland, C; Bolton, J L; Ford, B; Jampana, S; Tinker, J; Frohardt, R J; Guarraci, F A; Zewail-Foote, M

2012-02-01

The present study was designed to determine if male physiology and male reproductive behavior predict reproductive success in Long-Evans rats. Mating behavior was observed in sexually naïve, naturally cycling female rats during behavioral estrous that were given the opportunity to mate with two males simultaneously. DNA analysis of offspring born following these mating encounters was used to identify the paternity of each pup. In order to assess the effect of mate choice during these mating encounters on reproductive success, one male rat in each pair was categorized as the preferred mate if the female spent more time (>50%) with him during the mating test of the present study. Furthermore, each male in the pairs was categorized as "attractive" or "non-attractive" by computing the number of females that preferred each male across many mating tests. Similar to results reported in Lovell et al. (2007), during 76% of these mating tests the same male rat in each pair was preferred by different female rats. Overall attractiveness of individual male rats predicted reproductive success in the present study. Interestingly, "attractive" males sired significantly FEWER pups than "non-attractive" males. Neither behavioral (e.g., latency to first sexual stimulation, number of sexual stimulations) nor physiological measures (e.g., body weight, urinary testosterone levels) of male rats predicted their reproductive success. In conclusion, the present results indicate that certain features of some males are more attractive to females, but attractive males are at a reproductive disadvantage (as measured by the number of pups sired). Although basal urinary testosterone levels did not differ between males that sired the majority of pups in a litter and males that sired few or none of the pups in a litter, aggression and/or other physiological measures of fertility (e.g., penile reflexes) may differ between males that are attractive to females and those that have a reproductive advantage. Copyright © 2011 Elsevier Inc. All rights reserved.

Proteomic Analysis of Male-Fertility Restoration in CMS Onion

USDA-ARS?s Scientific Manuscript database

The production of hybrid-onion seed is dependent on cytoplasmic-genic male sterility (CMS) systems. For the most commonly used CMS, male-sterile (S) cytoplasm interacts with a dominant allele at one nuclear male-fertility restoration locus (Ms) to condition male fertility. We are using proteomics ...

Sexual behavior attenuates the effects of chronic stress in body weight, testes, sexual accessory glands, and plasma testosterone in male rats.

PubMed

Retana-Márquez, S; Vigueras-Villaseñor, R M; Juárez-Rojas, L; Aragón-Martínez, A; Torres, G Reyes

2014-11-01

The aim of this study was to evaluate whether continuous sexual behavior could attenuate the effects of chronic stress on spermatogenesis, sexual glands, plasma testosterone and corticosterone in sexually experienced male rats. Rats were exposed to stress by immersion in cold water (ICW) daily for 20 or 50 consecutive days. Plasma testosterone and corticosterone, masculine sexual behavior, as well as the number of offspring, the epithelial area of seminiferous, prostatic and seminal glands were assessed. In stressed males, body and testicular weights decreased, male sexual behavior was disrupted, and adrenal weights increased. In males stressed for 50 days, prostate and seminal glands had lower weights compared with controls. Prostate and seminal epithelial areas also decreased in these males. Seminiferous tubules in testes from rats stressed for 20 or 50 days showed several degenerative signs, such as vacuoles in the basal epithelium, with picnotic indicia; moderate to severe exfoliation of degenerative germinal cells in the tubule lumen was also observed. In males stressed for 50 days a significant decrease in seminiferous epithelial area was observed from stages I-VIII, regardless of copulation. The litters from females that copulated with males stressed for 50 days decreased significantly. Chronic stress caused increase in plasma levels of corticosterone, which were higher in males stressed for 20 days than in males stressed for 50 days. Testosterone decreased in stressed males and it was lower in males stressed for 50 days. In stressed males allowed to copulate, body and testicular weights were similar to controls. Adrenal, seminal glands, and prostate weights, as well as epithelial areas of males stressed for 50 days allowed to copulate were also similar to controls. Corticosterone was lower than in males stressed for 50 days, but still higher than in controls. Testosterone in males stressed for 50 days and allowed to copulate was higher than in stressed males not allowed to copulate and control males without copulation, but still lower than in control copulating males. These results show that chronic stress causes germ cell loss in testes and a decrease in prostate and seminal epithelium, possibly as a result of testosterone decrease, affecting fertility. Continuous copulation can attenuate the effects of stress on testosterone levels and on the epithelial area in male sexual glands, but not on the seminiferous epithelium after 50 days of stress. Copyright © 2014 Elsevier Inc. All rights reserved.

The Dominant Ms Allele in Onion Shows Reduced Penetrance

USDA-ARS?s Scientific Manuscript database

The most commonly used source of cytoplasmic male sterility in onion is controlled by the interaction of the cytoplasm [male-sterile (S) or normal (N) male-fertile] and one nuclear male-fertility-restoration locus (Ms). Scoring of genotypes at Ms is generally done by testcrossing male-fertile to mal...

Graduating Black Males

ERIC Educational Resources Information Center

Bell, Edward Earl

2010-01-01

Background: The graduation numbers for Black males are dismal, chilling, and undeniably pathetic. The nation graduates only 47% of Black males who enter the 9th grade. The infusion of federal dollars and philanthropic support will not stop the trajectory of Black males who drop out of school. Black males face an upheaval educational battle;…

Occupational Status and Suicide.

ERIC Educational Resources Information Center

Lampert, Dominique I.; And Others

1984-01-01

Examined relationship between occupational status and suicide in California males since 1925. Findings show an inverse relationship between occupational status and suicide for all age groups. Over time, male suicide rates have increased, particularly for employed males over 65, employed males aged 14 to 24, and males in low-status occupations.…

Vaginal secretions increase the likelihood of intermale aggression in Syrian hamsters.

PubMed

Fischer, R B; Brown, P S

1993-08-01

Although sexually receptive female hamsters prefer dominant males as mating partners, it is not clear what role the female might play facilitating aggressive interactions among males that would lead to the establishment of a status relationship. The ability of vaginal odors to stimulate male aggression was examined by paring randomly chosen males in a neutral arena with vaginal odors either present or absent. Males exhibited significantly more aggression when tested in the scented arena. Vaginal odors are efficient broadcast signals serving to space females, attract males, and to stimulate aggressive interactions among the males while inhibiting aggression towards the female.

Female preferences drive the evolution of mimetic accuracy in male sexual displays.

PubMed

Coleman, Seth William; Patricelli, Gail Lisa; Coyle, Brian; Siani, Jennifer; Borgia, Gerald

2007-10-22

Males in many bird species mimic the vocalizations of other species during sexual displays, but the evolutionary and functional significance of interspecific vocal mimicry is unclear. Here we use spectrographic cross-correlation to compare mimetic calls produced by male satin bowerbirds (Ptilonorhynchus violaceus) in courtship with calls from several model species. We show that the accuracy of vocal mimicry and the number of model species mimicked are both independently related to male mating success. Multivariate analyses revealed that these mimetic traits were better predictors of male mating success than other male display traits previously shown to be important for male mating success. We suggest that preference-driven mimetic accuracy may be a widespread occurrence, and that mimetic accuracy may provide females with important information about male quality. Our findings support an alternative hypothesis to help explain a common element of male sexual displays.

Is There a Delay in Diagnosis of Duchenne Muscular Dystrophy Among Preterm-Born Males?

PubMed

Soim, Aida; Smith, Michael G; Kwon, Jennifer M; Mann, Joshua R; Thomas, Shiny; Ciafaloni, Emma

2018-07-01

The objective of this study was to investigate whether males who were born preterm took longer to receive a Duchenne muscular dystrophy diagnosis than term males. Data for males with Duchenne muscular dystrophy identified through a population-based surveillance system were analyzed using a Kaplan-Meier estimator. The first signs and symptoms were noted at a median age of 2 years in both groups. Median age when first signs and symptoms prompted medical evaluation was 2.59 years among preterm and 4.01 years among term males. Median age at definitive diagnosis was 4.25 years and 4.92 years for preterm and term males, respectively. Neither difference was statistically significant. Preterm males tended to be seen for their initial medical evaluation earlier than term males, though they were not diagnosed significantly earlier. It may take clinicians longer after the initial evaluation of preterm males to arrive at a Duchenne muscular dystrophy diagnosis.

Visual perception of male body attractiveness.

PubMed

Fan, J; Dai, W; Liu, F; Wu, J

2005-02-07

Based on 69 scanned Chinese male subjects and 25 Caucasian male subjects, the present study showed that the volume height index (VHI) is the most important visual cue to male body attractiveness of young Chinese viewers among the many body parameters examined in the study. VHI alone can explain ca. 73% of the variance of male body attractiveness ratings. The effect of VHI can be fitted with two half bell-shaped exponential curves with an optimal VHI at 17.6 l m(-2) and 18.0 l m(-2) for female raters and male raters, respectively. In addition to VHI, other body parameters or ratios can have small, but significant effects on male body attractiveness. Body proportions associated with fitness will enhance male body attractiveness. It was also found that there is an optimal waist-to-hip ratio (WHR) at 0.8 and deviations from this optimal WHR reduce male body attractiveness.

Hybrid male sterility and genome-wide misexpression of male reproductive proteases.

PubMed

Gomes, Suzanne; Civetta, Alberto

2015-07-06

Hybrid male sterility is a common barrier to gene flow between species. Previous studies have posited a link between misregulation of spermatogenesis genes in interspecies hybrids and sterility. However, in the absence of fully fertile control hybrids, it is impossible to differentiate between misregulation associated with sterility vs. fast male gene regulatory evolution. Here, we differentiate between these two possibilities using a D. pseudoobscura species pair that experiences unidirectional hybrid sterility. We identify genes uniquely misexpressed in sterile hybrid male reproductive tracts via RNA-seq. The sterile male hybrids had more misregulated and more over or under expressed genes relative to parental species than the fertile male hybrids. Proteases were the only gene ontology class overrepresented among uniquely misexpressed genes, with four located within a previously identified hybrid male sterility locus. This result highlights the potential role of a previously unexplored class of genes in interspecific hybrid male sterility and speciation.

Hybrid male sterility and genome-wide misexpression of male reproductive proteases

PubMed Central

Gomes, Suzanne; Civetta, Alberto

2015-01-01

Hybrid male sterility is a common barrier to gene flow between species. Previous studies have posited a link between misregulation of spermatogenesis genes in interspecies hybrids and sterility. However, in the absence of fully fertile control hybrids, it is impossible to differentiate between misregulation associated with sterility vs. fast male gene regulatory evolution. Here, we differentiate between these two possibilities using a D. pseudoobscura species pair that experiences unidirectional hybrid sterility. We identify genes uniquely misexpressed in sterile hybrid male reproductive tracts via RNA-seq. The sterile male hybrids had more misregulated and more over or under expressed genes relative to parental species than the fertile male hybrids. Proteases were the only gene ontology class overrepresented among uniquely misexpressed genes, with four located within a previously identified hybrid male sterility locus. This result highlights the potential role of a previously unexplored class of genes in interspecific hybrid male sterility and speciation. PMID:26146165

Alternative reproductive tactics and the propensity of hybridization.

PubMed

Tynkkynen, K; Raatikainen, K J; Häkkilä, M; Haukilehto, E; Kotiaho, J S

2009-12-01

One explanation for hybridization between species is the fitness benefits it occasionally confers to the hybridizing individuals. This explanation is possible in species that have evolved alternative male reproductive tactics: individuals with inferior tactics might be more prone to hybridization provided it increases their reproductive success and fitness. Here we experimentally tested whether the propensity of hybridization in the wild depends on male reproductive tactic in Calopteryx splendens damselflies. Counter to our expectation, it was males adopting the superior reproductive tactic (territoriality) that had greatest propensity to hybridize than males adopting the inferior tactics (sneakers and floaters). Moreover, among the territorial males, the most ornamented males had greatest propensity to hybridize whereas the pattern was reversed in the sneaker males. Our results suggest that there is fluctuating selection on male mate discrimination against heterospecific females depending on both ornament size and the male's reproductive tactic.

Wing Morphometry and Acoustic Signals in Sterile and Wild Males: Implications for Mating Success in Ceratitis capitata

PubMed Central

de Souza, João Maria Gomes Alencar; Molina, Wagner Franco; de Almeida, Lúcia Maria; de Gouveia, Milson Bezerra; de Macêdo, Francisco Pepino; Laumann, Raul Alberto; Paranhos, Beatriz Aguiar Jordão

2015-01-01

The sterile insect technique (SIT) is widely utilized in the biological control of fruit flies of the family Tephritidae, particularly against the Mediterranean fruit fly. This study investigated the interaction between mating success and morphometric variation in the wings and the production of acoustic signals among three male groups of Ceratitis capitata (Wiedemann): (1) wild males, (2) irradiated with Co-60 (steriles), and (3) irradiated (steriles) and treated with ginger oil. The canonical variate analysis discriminated two groups (males irradiated and males wild), based on the morphological shape of the wings. Among males that emit buzz signals, wild males obtained copulation more frequently than males in Groups 2 and 3. The individuals of Group 3 achieved more matings than those in Group 2. Wild males displayed lower pulse duration, higher intervals between pulses, and higher dominant frequency. Regarding the reproductive success, the morphological differences in the wings' shape between accepted and nonaccepted males are higher in wild males than in the irradiated ones. The present results can be useful in programs using the sterile insect technique for biological control of C. capitata. PMID:26075293

Effect of hepatitis B virus infection on sperm quality and oxidative stress state of the semen of infertile males.

PubMed

Qian, Li; Li, Qiong; Li, Haibo

2016-09-01

The effects of hepatitis B virus (HBV) infection on sperm quality and oxidative stress state of the semen of infertile males remain undetermined. Normal males and 60 semen samples from infertile males (with or without HBV infection) were subjected to semen analysis. Semen volume, semen pH, sperm density, percentage of forward, movement of sperm, sperm activation rate, sperm survival rate, rate of normal sperm morphology of infertile males with HBV infection were significantly lower than those of infertile males without genital infection and of normal males (P<.05), while interleukin (IL)-17, IL-18, and malondialdehyde (MDA) levels in subjects with HBV infection were significantly higher than those of infertile males without genital infection and of normal males (P<.05). In patients with HBV infection, MDA level was found to be negatively correlated with semen quality, but positively correlated with semen IL-17 and IL-18 concentrations. HBV infection increased MDA level, induced abnormal expression of IL-17 and IL-18, and negatively affected male reproductive capacity, resulting in male infertility. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Asymmetric reproductive character displacement in male aggregation behaviour

PubMed Central

Pfennig, Karin S.; Stewart, Alyssa B.

2011-01-01

Reproductive character displacement—the evolution of traits that minimize reproductive interactions between species—can promote striking divergence in male signals or female mate preferences between populations that do and do not occur with heterospecifics. However, reproductive character displacement can affect other aspects of mating behaviour. Indeed, avoidance of heterospecific interactions might contribute to spatial (or temporal) aggregation of conspecifics. We examined this possibility in two species of hybridizing spadefoot toad (genus Spea). We found that in Spea bombifrons sympatric males were more likely than allopatric males to associate with calling males. Moreover, contrary to allopatric males, sympatric S. bombifrons males preferentially associated with conspecific male calls. By contrast, Spea multiplicata showed no differences between sympatry and allopatry in likelihood to associate with calling males. Further, sympatric and allopatric males did not differ in preference for conspecifics. However, allopatric S. multiplicata were more variable than sympatric males in their responses. Thus, in S. multiplicata, character displacement may have refined pre-existing aggregation behaviour. Our results suggest that heterospecific interactions can foster aggregative behaviour that might ultimately contribute to clustering of conspecifics. Such clustering can generate spatial or temporal segregation of reproductive activities among species and ultimately promote reproductive isolation. PMID:21177683

XY pair associates with the synaptonemal complex of autosomal male-sterile translocations in pachytene spermatocytes of the mouse (Mus musculus).

PubMed

Forejt, J; Gregorová, S; Goetz, P

1981-01-01

Analysis of the chromosome behaviour at pachytene has been performed by means of the silver staining technique visualizing the synaptonemal complexes (SCs) in male mice heterozygous for the male-sterile translocations T(5;12)31Hm T(16;17)43H and T(7;19)145H, respectively. the T(9;17)138Ca male heterozygotes and T43H/T43H homozygous males were used as fertile controls. The sterile mice displayed a high frequency (about 60%) of pachytene spermatocytes with autosomal translocation configuration located in close vicinity of the XY pair. The dense round body (XAB), normally located near the X-chromosome axis in fertile males, exhibited abnormal affinity to translocation configuration in the sterile translocation heterozygotes. The incomplete synapsis of autosomes involved in translocation configuration was observed in more than 70% of the pachytene spermatocytes with the male-sterile translocations but less than 20% of the cells from T138Ca fertile male.s. A hypothesis relating the spermatogenic arrest of carriers of male-sterile rearrangements to the presumed interference with X chromosome inactivation in male meiosis is discussed.

Sperm competition games: optimal sperm allocation in response to the size of competing ejaculates.

PubMed

Engqvist, Leif; Reinhold, Klaus

2007-01-22

Sperm competition theory predicts that when males are certain of sperm competition, they should decrease sperm investment in matings with an increasing number of competing ejaculates. How males should allocate sperm when competing with differently sized ejaculates, however, has not yet been examined. Here, we report the outcomes of two models assuming variation in males' sperm reserves and males being faced with different amounts of competing sperm. In the first 'spawning model', two males compete instantaneously and both are able to assess the sperm competitive ability of each other. In the second 'sperm storage model', males are sequentially confronted with situations involving different levels of sperm competition, for instance different amounts of sperm already stored by the female mating partner. In both of the models, we found that optimal sperm allocation will strongly depend on the size of the male's sperm reserve. Males should always invest maximally in competition with other males that are equally strong competitors. That is, for males with small sperm reserves, our model predicts a negative correlation between sperm allocation and sperm competition intensity, whereas for males with large sperm reserves, this correlation is predicted to be positive.

Coevolution of female ovulatory signals and male-male competition in primates.

PubMed

Nakahashi, Wataru

2016-03-07

Visual signals of ovulation vary among primate species. Although slight ovulatory signals are considered primate ancestral traits of which some species still exhibit, some show prominent swelling of their perineal skin (exaggerated sexual swellings) and others do not exhibit any signals of ovulation (concealed ovulation). These signals strongly affect male mating behaviors. I develop an evolutionary model of female ovulatory signals and male-male competition. I assume that each male allocates his effort between attraction of females and male-male competition for dominance. Each female gains a benefit if she is fertile and free from the alpha male who always guards one of the most fertile females in the group, but suffers a cost if she expresses a different ovulatory signal from an ancestral trait. I show that various types of ovulatory signals may evolve and can be multistable. Male-male competition becomes intense when the signal honestly indicates ovulation. Ovulatory signals may evolve to be less exaggerated in unimale groups than in multimale groups and monogamy is more likely to evolve when ovulation is concealed. These results may partly explain why various types of primate ovulatory signals evolved and how they have affected primate societies. Copyright © 2015 Elsevier Ltd. All rights reserved.

The agricultural contaminant 17β-trenbolone disrupts male-male competition in the guppy (Poecilia reticulata).

PubMed

Tomkins, Patrick; Saaristo, Minna; Bertram, Michael G; Tomkins, Raymond B; Allinson, Mayumi; Wong, Bob B M

2017-11-01

Despite a growing literature highlighting the potential impact of human-induced environmental change on mechanisms of sexual selection, relatively little is known about the effects of chemical pollutants on male-male competition. One class of environmental pollutant likely to impact male competitive interactions is the endocrine-disrupting chemicals (EDCs), a large and heterogeneous group of chemical contaminants with the potential to influence morphology, physiology and behaviour at minute concentrations. One EDC of increasing concern is the synthetic, androgenic steroid 17β-trenbolone, which is used globally to promote growth in beef cattle. Although 17β-trenbolone has been found to cause severe morphological and behavioural abnormalities in fish, its potential impact on male-male competition has yet to be investigated. To address this, we exposed wild male guppies (Poecilia reticulata) to an environmentally realistic concentration of 17β-trenbolone (average measured concentration: 8 ng/L) for 21 days using a flow-through system. We found that, in the presence of a competitor, 17β-trenbolone-exposed males carried out more frequent aggressive behaviours towards rival males than did unexposed males, as well as performing less courting behaviour and more sneak (i.e., coercive) mating attempts towards females. Considering that, by influencing mating outcomes, male-male competition has important consequences for population dynamics and broader evolutionary processes, this study highlights the need for greater understanding of the potential impact of EDCs on the mechanisms of sexual selection. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Male Weaponry in a Fighting Cricket

PubMed Central

Judge, Kevin A.; Bonanno, Vanessa L.

2008-01-01

Sexually selected male weaponry is widespread in nature. Despite being model systems for the study of male aggression in Western science and for cricket fights in Chinese culture, field crickets (Orthoptera, Gryllidae, Gryllinae) are not known to possess sexually dimorphic weaponry. In a wild population of the fall field cricket, Gryllus pennsylvanicus, we report sexual dimorphism in head size as well as the size of mouthparts, both of which are used when aggressive contests between males escalate to physical combat. Male G. pennsylvanicus have larger heads, maxillae and mandibles than females when controlling for pronotum length. We conducted two experiments to test the hypothesis that relatively larger weaponry conveys an advantage to males in aggressive contests. Pairs of males were selected for differences in head size and consequently were different in the size of maxillae and mandibles. In the first experiment, males were closely matched for body size (pronotum length), and in the second, they were matched for body mass. Males with proportionately larger weaponry won more fights and increasing differences in weaponry size between males increased the fighting success of the male with the larger weaponry. This was particularly true when contests escalated to grappling, the most intense level of aggression. However, neither contest duration nor intensity was related to weaponry size as predicted by models of contest settlement. These results are the first evidence that the size of the head capsule and mouthparts are under positive selection via male-male competition in field crickets, and validate 800-year-old Chinese traditional knowledge. PMID:19107188

Sexually stimulated testosterone release in male mice (Mus musculus): roles of genotype and sexual arousal.

PubMed

James, Peter J; Nyby, John G; Saviolakis, George A

2006-09-01

In virtually every mammalian species examined, some males exhibit reflexive testosterone release upon encountering a novel female (or female-related stimulus). At the same time, not every individual male (or every published study) provides evidence for reflexive testosterone release. Four experiments using house mice (Mus musculus) examined the hypothesis that both the male's genotype and his degree of sexual arousal (as indexed by ultrasonic mating calls) are related to such variability. In Experiment 1, CF-1 males exhibited reflexive testosterone elevations 30 min after encountering female urine. CK males, on the other hand, did not exhibit testosterone elevations 20, 30, 50, 60, or 80 min after encountering female urine (Experiments 1 and 2) suggesting this strain incapable of reflexive release. In Experiment 3, we measured both mating calls and reflexive testosterone release in response to female urine in CF-1 and CK males. Most males of both strains called vigorously to female urine but not to water. But, only CF-1 males exhibited significant testosterone elevations to female urine. In Experiment 4, DBA/2J males called vigorously to females followed by testosterone elevations 30 min later. The first 3 experiments support the hypothesis that male genotype is an important variable underlying mammalian reflexive testosterone release. Statistically significant correlations between mating calls in the first minute after stimulus exposure and testosterone elevations 30 min later (Experiments 3 and 4) support the hypothesis that, in capable males, reflexive testosterone release is related to the male's initial sexual arousal.

Low Mate Encounter Rate Increases Male Risk Taking in a Sexually Cannibalistic Praying Mantis

PubMed Central

Brown, William D.; Muntz, Gregory A.; Ladowski, Alexander J.

2012-01-01

Male praying mantises are forced into the ultimate trade-off of mating versus complete loss of future reproduction if they fall prey to a female. The balance of this trade-off will depend both on (1) the level of predatory risk imposed by females and (2) the frequency of mating opportunities for males. We report the results of a set of experiments that examine the effects of these two variables on male risk-taking behavior and the frequency of sexual cannibalism in the praying mantis Tenodera sinensis. We experimentally altered the rate at which males encountered females and measured male approach and courtship behavior under conditions of high and low risk of being attacked by females. We show that male risk taking depends on prior access to females. Males with restricted access to females showed greater risk-taking behavior. When males were given daily female encounters, they responded to greater female-imposed risk by slowing their rate of approach and remained a greater distance from a potential mate. In contrast, males without recent access to mates were greater risk-takers; they approached females more rapidly and to closer proximity, regardless of risk. In a second experiment, we altered male encounter rate with females and measured rates of sexual cannibalism when paired with hungry or well-fed females. Greater risk-taking behavior by males with low mate encounter rates resulted in high rates of sexual cannibalism when these males were paired with hungry females. PMID:22558146

Heritable determinants of male fertilization success in the nematode Caenorhabditis elegans

PubMed Central

2011-01-01

Background Sperm competition is a driving force in the evolution of male sperm characteristics in many species. In the nematode Caenorhabditis elegans, larger male sperm evolve under experimentally increased sperm competition and larger male sperm outcompete smaller hermaphrodite sperm for fertilization within the hermaphrodite reproductive tract. To further elucidate the relative importance of sperm-related traits that contribute to differential reproductive success among males, we quantified within- and among-strain variation in sperm traits (size, rate of production, number transferred, competitive ability) for seven male genetic backgrounds known previously to differ with respect to some sperm traits. We also quantified male mating ability in assays for rates of courtship and successful copulation, and then assessed the roles of these pre- and post-mating traits in first- and second-male fertilization success. Results We document significant variation in courtship ability, mating ability, sperm size and sperm production rate. Sperm size and production rate were strong indicators of early fertilization success for males that mated second, but male genetic backgrounds conferring faster sperm production make smaller sperm, despite virgin males of all genetic backgrounds transferring indistinguishable numbers of sperm to mating partners. Conclusions We have demonstrated that sperm size and the rate of sperm production represent dominant factors in determining male fertilization success and that C. elegans harbors substantial heritable variation for traits contributing to male reproductive success. C. elegans provides a powerful, tractable system for studying sexual selection and for dissecting the genetic basis and evolution of reproduction-related traits. PMID:21492473

Heritable determinants of male fertilization success in the nematode Caenorhabditis elegans.

PubMed

Murray, Rosalind L; Kozlowska, Joanna L; Cutter, Asher D

2011-04-14

Sperm competition is a driving force in the evolution of male sperm characteristics in many species. In the nematode Caenorhabditis elegans, larger male sperm evolve under experimentally increased sperm competition and larger male sperm outcompete smaller hermaphrodite sperm for fertilization within the hermaphrodite reproductive tract. To further elucidate the relative importance of sperm-related traits that contribute to differential reproductive success among males, we quantified within- and among-strain variation in sperm traits (size, rate of production, number transferred, competitive ability) for seven male genetic backgrounds known previously to differ with respect to some sperm traits. We also quantified male mating ability in assays for rates of courtship and successful copulation, and then assessed the roles of these pre- and post-mating traits in first- and second-male fertilization success. We document significant variation in courtship ability, mating ability, sperm size and sperm production rate. Sperm size and production rate were strong indicators of early fertilization success for males that mated second, but male genetic backgrounds conferring faster sperm production make smaller sperm, despite virgin males of all genetic backgrounds transferring indistinguishable numbers of sperm to mating partners. We have demonstrated that sperm size and the rate of sperm production represent dominant factors in determining male fertilization success and that C. elegans harbors substantial heritable variation for traits contributing to male reproductive success. C. elegans provides a powerful, tractable system for studying sexual selection and for dissecting the genetic basis and evolution of reproduction-related traits.

Bone-eating Osedax females and their 'harems' of dwarf males are recruited from a common larval pool.

PubMed

Vrijenhoek, R C; Johnson, S B; Rouse, G W

2008-10-01

Extreme male dwarfism occurs in Osedax (Annelida: Siboglinidae), marine worms with sessile females that bore into submerged bones. Osedax are hypothesized to use environmental sex determination, in which undifferentiated larvae that settle on bones develop as females, and subsequent larvae that settle on females transform into dwarf males. This study addresses several hypotheses regarding possible recruitment sources for the males: (i) common larval pool--males and females are sampled from a common pool of larvae; (ii) neighbourhood--males are supplied by a limited number of neighbouring females; and (iii) arrhenotoky--males are primarily the sons of host females. Osedax rubiplumus were sampled from submerged whalebones located at 1820-m and 2893-m depths in Monterey Bay, California. Immature females typically did not host males, but mature females maintained male 'harems' that grew exponentially in the number of males as female size increased. Allozyme analysis of the females revealed binomial proportions of nuclear genotypes, an indication of random sexual mating. Analysis of mitochondrial DNA sequences from the male harems and their host females allowed us to reject the arrhenotoky and neighbourhood hypotheses for male recruitment. No significant partitioning of mitochondrial diversity existed between the male and female sexes, or between subsamples of worms collected at different depths or during different years (2002-2007). Mitochondrial sequence diversity was very high in these worms, suggesting that as many as 10(6) females contributed to a common larval pool from which the two sexes were randomly drawn.

Males do not see only red: UV wavelengths and male territorial aggression in the three-spined stickleback ( Gasterosteus aculeatus)

NASA Astrophysics Data System (ADS)

Rick, Ingolf P.; Bakker, Theo C. M.

2008-07-01

Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks ( Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback.

Behaviour of Arctic charr Salvelinus alpinus during an induced mating season in captivity: how male relative size influences male behavioural investment and female preference over time.

PubMed

Bolgan, M; O'Brien, J; Picciulin, M; Manning, L; Gammell, M

2017-04-01

The behaviour of sexually mature Arctic charr Salvelinus alpinus specimens (fifth farm generation) was observed in captivity for four consecutive days. Only agonistic interactions between males of different size were facilitated on the first 2 days, while both agonistic and courtship interactions were possible from the third day up to the end of the experiment. The reliability of behavioural analysis was assessed in order to reduce the possibility of observer errors within the generated datasets. The behavioural investment of big males, small males and females was analysed using general linear models (two-way repeated measures ANOVAs with time and male size as factors). A peak in the agonistic interactions between males occurred during the first day of interactions, where the agonistic investment of big males was significantly higher than that of small males. This resulted in an increased investment in submissive behaviour by the small males, who consistently performed submissive behaviours from the second day of interactions up to the end of the trial. Big males were found to invest significantly more than small males in courtship behaviours for the duration of the trial. Even though females performed inter-sexual behaviours towards both big and small males for the entire observation period, female interaction rate towards big males was higher than towards small males. This study suggests that both male investment in mating behaviour and female preference might be related to male characteristics such as body length and that S. alpinus behavioural patterns and mate choice cues might be strongly context-related and characterized by high levels of behavioural plasticity (i.e. presence-absence of certain behavioural units or potential reversal of a mate choice cue) within the same species. Finally, in light of this, some conservation measures are discussed. In particular, effective management plans should take into account the high level of behavioural plasticity likely to be occurring in this species. © 2016 The Fisheries Society of the British Isles.

Do male breeding displays function to attract mates or defend territories? The explanatory role of mate and site fidelity

USGS Publications Warehouse

Lanctot, Richard B.; Sandercock, B.K.; Kempenaers, Bart

2000-01-01

Many shorebirds show elaborate breeding displays that include aerial flights and ground displays accompanied by song. The mate attraction hypothesis suggests that breeding displays function to attract mates and maintain pair bonds, whereas the territory defense hypothesis suggests breeding displays function in defining and defending nesting and feeding territories. We tested these hypotheses in the Western Sandpiper (Calidris mauri) by contrasting the duration and level of male breeding displays among pairs that differed in their mate and site fidelity. As predicted by the mate attraction hypothesis, males performed the highest number of song sequences during pair formation, and males paired with their mate of a prior year sang less than males paired to new mates. Further, sitefaithful males mated to a new but experienced mate displayed significantly more than remated males or males new to the area. This suggests a male's prior familiarity with an area and his neighbors does not lessen his display rate as was predicted under the territory defense hypothesis. Limited support for the territory defense hypothesis came from observations of males performing breeding displays with neighboring males along nest territory boundaries. This behavior was short-lived, however, as males abandoned nesting areas after pair-formation and used adjacent or disjointed feeding areas during egg-laying and incubation. Male aggression (i.e., aerial and ground chases), as opposed to breeding displays, appeared to be the principal means of maintaining territory boundaries. Indeed, the rate at which males chased other males remained fairly constant and high throughout the breeding season. Male chasing behavior may also serve as a paternity guard to protect against extra-pair copulations. Our study also found that a female's prior breeding experience in an area correlated with a reduced display rate by her mate, particularly if that mate was new to the area. This indicates female characteristics may not only drive nest initiation, as has been shown in other studies, but are important in determining the duration and extent of male display.

Mating competitiveness of sterile male Anopheles coluzzii in large cages.

PubMed

Maïga, Hamidou; Damiens, David; Niang, Abdoulaye; Sawadogo, Simon P; Fatherhaman, Omnia; Lees, Rosemary S; Roux, Olivier; Dabiré, Roch K; Ouédraogo, Georges A; Tripet, Fréderic; Diabaté, Abdoulaye; Gilles, Jeremie R L

2014-11-26

Understanding the factors that account for male mating competitiveness is critical to the development of the sterile insect technique (SIT). Here, the effects of partial sterilization with 90 Gy of radiation on sexual competitiveness of Anopheles coluzzii allowed to mate in different ratios of sterile to untreated males have been assessed. Moreover, competitiveness was compared between males allowed one versus two days of contact with females. Sterile and untreated males four to six days of age were released in large cages (~1.75 sq m) with females of similar age at the following ratios of sterile males: untreated males: untreated virgin females: 100:100:100, 300:100:100, 500:100:100 (three replicates of each) and left for two days. Competitiveness was determined by assessing the egg hatch rate and the insemination rate, determined by dissecting recaptured females. An additional experiment was conducted with a ratio of 500:100:100 and a mating period of either one or two days. Two controls of 0:100:100 (untreated control) and 100:0:100 (sterile control) were used in each experiment. When males and females consort for two days with different ratios, a significant difference in insemination rate was observed between ratio treatments. The competitiveness index (C) of sterile males compared to controls was 0.53. The number of days of exposure to mates significantly increased the insemination rate, as did the increased number of males present in the untreated: sterile male ratio treatments, but the number of days of exposure did not have any effect on the hatch rate. The comparability of the hatch rates between experiments suggest that An. coluzzii mating competitiveness experiments in large cages could be run for one instead of two days, shortening the required length of the experiment. Sterilized males were half as competitive as untreated males, but an effective release ratio of at least five sterile for one untreated male has the potential to impact the fertility of a wild female population. However, further trials in field conditions with wild males and females should be undertaken to estimate the ratio of sterile males to wild males required to produce an effect on wild populations.

The effects of genetic manipulation, dieldrin treatment and irradiation on the mating competitiveness of male Anopheles arabiensis in field cages.

PubMed

Yamada, Hanano; Vreysen, Marc J B; Gilles, Jeremie R L; Munhenga, Givemore; Damiens, David D

2014-08-13

To enable the release of only sterile male Anopheles arabiensis mosquitoes for the sterile insect technique, the genetic background of a wild-type strain was modified to create a genetic sexing strain ANO IPCL1 that was based on a dieldrin resistance mutation. Secondly, the eggs of ANO IPCL1 require treatment with dieldrin to allow complete elimination of female L1 larvae from the production line. Finally, male mosquito pupae need to be treated with an irradiation dose of 75 Gy for sterilization. The effects of these treatments on the competitiveness of male An. arabiensis were studied. The competitiveness of ANO IPCL1 males that were treated either with irradiation or both dieldrin and irradiation, was compared with that of the wild-type strain (An. arabiensis Dongola) at a 1:1 ratio in 5.36 m3 semi-field cages located in a climate-controlled greenhouse. In addition, three irradiated: untreated male ratios were tested in semi-field cages (1:1, 5:1 and 10:1) and their competition for virgin wild-type females was assessed. The ANO IPCL1 males were equally competitive as the wild-type males in this semi-field setting. The ANO IPCL1 males irradiated at 75 Gy were approximately half as competitive as the unirradiated wild-type males. ANO IPCL1 males that had been treated with dieldrin as eggs, and irradiated with 75 Gy as pupae were slightly more competitive than males that were only irradiated. Ratios of 1:1, 5:1 and 10:1 irradiated ANO IPCL1 males: untreated wild-type males resulted in 31, 66 and 81% induced sterility in the female cage population, respectively. An irradiation dose of 75 Gy reduced the competitiveness of male ANO IPCL1 significantly and will need to be compensated by releasing higher numbers of sterile males in the field. However, the dieldrin treatment used to eliminate females appears to have an unexpected radioprotectant effect, however the mechanism is not understood. A sterile to wild-type ratio of 10:1 effectively reduced the population's fertility under the experimental field cage conditions, but further studies in the field will be needed to confirm the efficiency of sterile ANO IPCL1 males when competing against wild males for wild females.

Inheritance of steroid-independent male sexual behavior in male offspring of B6D2F1 mice.

PubMed

McInnis, Christine M; Bonthuis, Paul J; Rissman, Emilie F; Park, Jin Ho

2016-04-01

The importance of gonadal steroids in modulating male sexual behavior is well established. Individual differences in male sexual behavior, independent of gonadal steroids, are prevalent across a wide range of species, including man. However, the genetic mechanisms underlying steroid-independent male sexual behavior are poorly understood. A high proportion of B6D2F1 hybrid male mice demonstrates steroid-independent male sexual behavior (identified as "maters"), providing a mouse model that opens up avenues of investigation into the mechanisms regulating male sexual behavior in the absence of gonadal hormones. Recent studies have revealed several proteins that play a significant factor in regulating steroid-independent male sexual behavior in B6D2F1 male mice, including amyloid precursor protein (APP), tau, and synaptophysin. The specific goals of our study were to determine whether steroid-independent male sexual behavior was a heritable trait by determining if it was dependent upon the behavioral phenotype of the B6D2F1 sire, and whether the differential expression of APP, tau, and synaptophysin in the medial preoptic area found in the B6D2F1 sires that did and did not mate after gonadectomy was similar to those found in their male offspring. After adult B6D2F1 male mice were bred with C57BL/6J female mice, they and their male offspring (BXB1) were orchidectomized and identified as either maters or "non-maters". A significant proportion of the BXB1 maters was sired only from B6D2F1 maters, indicating that the steroid-independent male sexual behavior behavioral phenotype of the B6D2F1 hybrid males, when crossed with C57BL/6J female mice, is inherited by their male offspring. Additionally, APP, tau, and synaptophysin were elevated in in the medial preoptic area in both the B6D2F1 and BXB1 maters relative to the B6D2F1 and BXB1 non-maters, respectively, suggesting a potential genetic mechanism for the inheritance of steroid-independent male sexual behavior. Copyright © 2016 Elsevier Inc. All rights reserved.

Inheritance of steroid-independent male sexual behavior in male offspring of B6D2F1 mice

PubMed Central

McInnis, Christine M.; Bonthuis, Paul J.; Rissman, Emilie F.; Park, Jin Ho

2016-01-01

The importance of gonadal steroids in modulating male sexual behavior is well established. Individual differences in male sexual behavior, independent of gonadal steroids, are prevalent across a wide range of species, including man. However, the genetic mechanisms underlying steroid-independent male sexual behavior are poorly understood. A high proportion of B6D2F1 hybrid male mice demonstrate steroid-independent male sexual behavior (identified as “maters”), providing a mouse model that opens up avenues of investigation into the mechanisms regulating male sexual behavior in the absence of gonadal hormones. Recent studies have revealed several proteins that play a significant factor in regulating steroid-independent male sexual behavior in B6D2F1 male mice, including amyloid precursor protein (APP), tau, and synaptophysin. The specific goals of our study were to determine whether steroid-independent male sexual behavior was a heritable trait by determining if it was dependent upon the behavioral phenotype of the B6D2F1 sire, and whether the differential expression of APP, tau, and synaptophysin in the medial preoptic area found in the B6D2F1 sires that did and did not mate after gonadectomy was similar to those found in their male offspring. After adult B6D2F1 male mice were bred with C57BL/6J female mice, they and their male offspring (BXB1) were orchidectomized and identified as either maters or “non-maters.” A significant proportion of the BXB1 maters were sired only from B6D2F1 maters, indicating that the steroid-independent male sexual behavior behavioral phenotype of the B6D2F1 hybrid males, when crossed with C57BL/6J female mice, is inherited by their male offspring. Additionally, APP, tau, and synaptophysin were elevated in in the medial preoptic area in both the B6D2F1 and BXB1 maters relative to the B6D2F1 and BXB1 non-maters, respectively, suggesting a potential genetic mechanism for the inheritance of steroid-independent male sexual behavior. PMID:26940434

Familial patterning and prevalence of male androphilia among Istmo Zapotec men and muxes.

PubMed

Gómez, Francisco R; Semenyna, Scott W; Court, Lucas; Vasey, Paul L

2018-01-01

Male androphilia (i.e., male sexual attraction to other adult males) is known to cluster within families. Some studies demonstrate that male androphilia clusters in both the paternal and maternal familial lines, whereas other studies demonstrated that it clusters only in the latter. Most of these studies were conducted in Euro-American populations where fertility is low and the sexual orientation of male relatives can sometimes be difficult to ascertain. These two factors can potentially confound the results of such studies. To address these limitations, we examined the familial patterning of male androphilia among the Istmo Zapotec of Oaxaca, Mexico--a high fertility, non-Euro-American population where androphilic males are known locally as muxes, a third gender category. The Istmo Zapotec recognize two types of muxes--muxe gunaa and muxe nguiiu--who typify the transgender and cisgender forms of male androphilia, respectively. We compared the familial patterning of male androphilia between muxe gunaa and muxe nguiiu, as well as between gynephilic men and muxes (both cisgender and transgender forms combined). Istmo Zapotec muxe gunaa and muxe nguiiu exhibit similar familial patterning of male androphilia. Overall, muxes were characterized by significantly more muxe relatives than gynephilic men. This familial patterning was equivalent in both the paternal and maternal lines of muxes. The population prevalence rate of male androphilia was estimated to fall between 3.37-6.02% in the Istmo Zapotec. This is the first study that has compared cisgender and transgender androphilic males from the same high fertility population and demonstrated that the two do not differ with respect to the familial patterning of male androphilia.

Familial patterning and prevalence of male androphilia among Istmo Zapotec men and muxes

PubMed Central

Semenyna, Scott W.; Court, Lucas; Vasey, Paul L.

2018-01-01

Male androphilia (i.e., male sexual attraction to other adult males) is known to cluster within families. Some studies demonstrate that male androphilia clusters in both the paternal and maternal familial lines, whereas other studies demonstrated that it clusters only in the latter. Most of these studies were conducted in Euro-American populations where fertility is low and the sexual orientation of male relatives can sometimes be difficult to ascertain. These two factors can potentially confound the results of such studies. To address these limitations, we examined the familial patterning of male androphilia among the Istmo Zapotec of Oaxaca, Mexico––a high fertility, non-Euro-American population where androphilic males are known locally as muxes, a third gender category. The Istmo Zapotec recognize two types of muxes––muxe gunaa and muxe nguiiu––who typify the transgender and cisgender forms of male androphilia, respectively. We compared the familial patterning of male androphilia between muxe gunaa and muxe nguiiu, as well as between gynephilic men and muxes (both cisgender and transgender forms combined). Istmo Zapotec muxe gunaa and muxe nguiiu exhibit similar familial patterning of male androphilia. Overall, muxes were characterized by significantly more muxe relatives than gynephilic men. This familial patterning was equivalent in both the paternal and maternal lines of muxes. The population prevalence rate of male androphilia was estimated to fall between 3.37–6.02% in the Istmo Zapotec. This is the first study that has compared cisgender and transgender androphilic males from the same high fertility population and demonstrated that the two do not differ with respect to the familial patterning of male androphilia. PMID:29466410

Severe XIST hypomethylation clearly distinguishes (SRY+) 46,XX-maleness from Klinefelter syndrome.

PubMed

Poplinski, Andreas; Wieacker, Peter; Kliesch, Sabine; Gromoll, Jörg

2010-01-01

46,XX-maleness affects 1 in 20 000 live male newborns resulting in infertility and hypergonadotrophic hypogonadism. Although the phenotypes of XX-males have been well described, the molecular nature of the X chromosomes remains elusive. We assessed the X inactivation status by DNA methylation analysis of four informative loci and compared those to Klinefelter syndrome (KS) and Turner syndrome. Patient cohort consisted of ten sex-determining region of the Y (SRY+) XX-males, two (SRY-) XX-males, ten 47,XXY Klinefelter men, six 45,X Turner females and ten male and female control individuals each. Methylation analysis was carried out by bisulphite sequencing of DNA from peripheral blood lymphocytes analysing X-inactive-specific transcript (XIST), phosphoglycerate kinase 1 (PGK1), ferritin, heavy peptide-like 17 (FTHL17) and short stature homeobox (SHOX). XIST methylation was 18% in (SRY+) XX-males, and thus they were severely hypomethylated compared to (SRY-) XX-males (48%; P<0.01), Klinefelter men (44%; P<0.01) and female controls (47%; P<0.01). Turner females and male controls displayed a high degree of XIST methylation of 98 and 94% respectively. Methylation of PGK1, undergoing X inactivation, was not significantly reduced in (SRY+) XX-males compared to female controls in spite of severe XIST hypomethylation (51 vs 69%; P>0.05). FTHL17, escaping X inactivation, but undergoing cell-type-specific inactivation was similarly methylated in XX-males (89%), KS patients (87%) and female controls (90%). SHOX, an X inactivation escapee located in the pseudoautosomal region, displays similarly low degrees of methylation for XX-males (7%), KS patients (7%) and female controls (9%). XIST hypomethylation clearly distinguishes (SRY+) XX-males from Klinefelter men. It does not, however, impair appropriate epigenetic regulation of representative X-linked loci.

Female choice impacts residential male takeover in golden snub-nosed monkeys (Rhinopithecus roxellana).

PubMed

Fang, Gu; Chen, Jing; Pan, Ru-Liang; Qi, Xiao-Guang; Li, Bao-Guo

2018-07-18

In primate species with social systems consisting of one-male breeding units (OMUs), resident male takeover represents a major challenge to individual reproductive success and mating strategies. The golden snub-nosed monkey (Rhinopithecus roxellana) is characterized by large multilevel societies (MLS) comprised of several OMUs and all-male units (AMUs); however, the factors and mechanisms associated with resident male takeover, which offer important insight into primate reproduction and social strategies, are still poorly understood. Based on 5-year monitoring data from a free-ranging herd of golden monkeys from the Qinling Mountains in China, we categorized three phases of an OMU, that is, a rising phase, developing phase, and declining phase. The rising and declining phases were unstable periods in which male takeover in an OMU might occur. Factors causing takeover, such as leader male rank, fighting ability, reproduction rate, and affiliation (proximity, allogrooming), were analyzed for males and females and for different OMUs. Results indicated that the new resident male's fighting ability was lower than that of the former resident male in 23 cases. After replacement, the rank order of the new resident male significantly declined. Females involved in a takeover increased their distance from the resident male and decreased mating frequency during the three months prior to takeover. Females with infants under one-year-old had a marked effect on the specific time of takeover occurrence. These results suggested that female choice was the main factor deciding whether a takeover attempt was successful. Furthermore, rather than male conflict, females more often initiated and affected takeover and outcome, implying that the social status and competitive ability of the males played lesser roles during takeover.

Costs of mate-guarding in wild male long-tailed macaques (Macaca fascicularis): physiological stress and aggression.

PubMed

Girard-Buttoz, Cédric; Heistermann, Michael; Rahmi, Erdiansyah; Agil, Muhammad; Fauzan, Panji Ahmad; Engelhardt, Antje

2014-09-01

Mate-guarding is an important determinant of male reproductive success in a number of species. However, it is known to potentially incur costs. The aim of the present study was to assess the effect of mate-guarding on male physiological stress and aggression in long-tailed macaques, a species in which males mate-guard females to a lesser extent than predicted by the Priority of Access model (PoA). The study was carried out during two mating periods on three groups of wild long-tailed macaques in Indonesia by combining behavioral observations with non-invasive measurements of fecal glucocorticoid (fGC) levels. Mate-guarding was associated with a general rise in male stress hormone levels but, from a certain threshold of mate-guarding onwards, increased vigilance time was associated with a decrease in stress hormone output. Mate-guarding also increased male-male aggression rate and male vigilance time. Overall, alpha males were more physiologically stressed than other males independently of mating competition. Increased glucocorticoid levels during mate-guarding are most likely adaptive since it may help males to mobilize extra-energy required for mate-guarding and ultimately maintain a balanced energetic status. However, repeated exposure to high levels of stress over an extended period is potentially deleterious to the immune system and thus may carry costs. This potential physiological cost together with the cost of increased aggression mate-guarding male face may limit the male's ability to mate-guard females, explaining the deviance from the PoA model observed in long-tailed macaques. Comparing our results to previous findings we discuss how ecological factors, reproductive seasonality and rank achievement may modulate the extent to which costs of mate-guarding limit male monopolization abilities. Copyright © 2014. Published by Elsevier Inc.

Conflict between background matching and social signalling in a colour-changing freshwater fish

PubMed Central

Rodgers, Gwendolen M.; Morrell, Lesley J.

2016-01-01

The ability to change coloration allows animals to modify their patterning to suit a specific function. Many freshwater fishes, for example, can appear cryptic by altering the dispersion of melanin pigment in the skin to match the visual background. However, melanin-based pigments are also used to signal dominance among competing males; thus colour change for background matching may conflict with colour change for social status signalling. We used a colour-changing freshwater fish to investigate whether colour change for background matching influenced aggressive interactions between rival males. Subordinate males that had recently darkened their skin for background matching received heightened aggression from dominant males, relative to males whose coloration had not changed. We then determined whether the social status of a rival male, the focal male's previous social status, and his previous skin coloration, affected a male's ability to change colour for background matching. Social status influenced skin darkening in the first social encounter, with dominant males darkening more than subordinate males, but there was no effect of social status on colour change in the second social encounter. We also found that the extent of skin colour change (by both dominant and subordinate males) was dependent on previous skin coloration, with dark males displaying a smaller change in coloration than pale males. Our findings suggest that skin darkening for background matching imposes a significant social cost on subordinate males in terms of increased aggression. We also suggest that the use of melanin-based signals during social encounters can impede subsequent changes in skin coloration for other functions, such as skin darkening for background matching. PMID:27429764

Chemical and visual communication during mate searching in rock shrimp.

PubMed

Díaz, Eliecer R; Thiel, Martin

2004-06-01

Mate searching in crustaceans depends on different communicational cues, of which chemical and visual cues are most important. Herein we examined the role of chemical and visual communication during mate searching and assessment in the rock shrimp Rhynchocinetes typus. Adult male rock shrimp experience major ontogenetic changes. The terminal molt stages (named "robustus") are dominant and capable of monopolizing females during the mating process. Previous studies had shown that most females preferably mate with robustus males, but how these dominant males and receptive females find each other is uncertain, and is the question we examined herein. In a Y-maze designed to test for the importance of waterborne chemical cues, we observed that females approached the robustus male significantly more often than the typus male. Robustus males, however, were unable to locate receptive females via chemical signals. Using an experimental set-up that allowed testing for the importance of visual cues, we demonstrated that receptive females do not use visual cues to select robustus males, but robustus males use visual cues to find receptive females. Visual cues used by the robustus males were the tumults created by agitated aggregations of subordinate typus males around the receptive females. These results indicate a strong link between sexual communication and the mating system of rock shrimp in which dominant males monopolize receptive females. We found that females and males use different (sex-specific) communicational cues during mate searching and assessment, and that the sexual communication of rock shrimp is similar to that of the American lobster, where females are first attracted to the dominant males by chemical cues emitted by these males. A brief comparison between these two species shows that female behaviors during sexual communication contribute strongly to the outcome of mate searching and assessment.

Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination

PubMed Central

Nabe-Nielsen, Jacob; Dietz, Rune; Sonne, Christian; Grimm, Volker

2016-01-01

Polar bears (Ursus maritimus) from East Greenland and Svalbard exhibited very high concentrations of polychlorinated biphenyls (PCBs) in the 1980s and 1990s. In Svalbard, slow population growth during that period was suspected to be linked to PCB contamination. In this case study, we explored how PCBs could have impacted polar bear population growth and/or male reproductive success in Svalbard during the mid-1990s by reducing the fertility of contaminated males. A dose–response relationship linking the effects of PCBs to male polar bear fertility was extrapolated from studies of the effects of PCBs on sperm quality in rodents. Based on this relationship, an individual-based model of bear interactions during the breeding season predicted fertilization success under alternative assumptions regarding male–male competition for females. Contamination reduced pregnancy rates by decreasing the availability of fertile males, thus triggering a mate-finding Allee effect, particularly when male–male competition for females was limited or when infertile males were able to compete with fertile males for females. Comparisons of our model predictions on age-dependent reproductive success of males with published empirical observations revealed that the low representation of 10–14-year-old males among breeding males documented in Svalbard in mid-1990s could have resulted from PCB contamination. We conclude that contamination-related male infertility may lead to a reduction in population growth via an Allee effect. The magnitude of the effect is largely dependent on the population-specific mating system. In eco-toxicological risk assessments, appropriate consideration should therefore be given to negative effects of contaminants on male fertility and male mating behaviour. PMID:27903868

Mate choice when males are in patches: optimal strategies and good rules of thumb.

PubMed

Hutchinson, John M C; Halupka, Konrad

2004-11-07

In standard mate-choice models, females encounter males sequentially and decide whether to inspect the quality of another male or to accept a male already inspected. What changes when males are clumped in patches and there is a significant cost to travel between patches? We use stochastic dynamic programming to derive optimum strategies under various assumptions. With zero costs to returning to a male in the current patch, the optimal strategy accepts males above a quality threshold which is constant whenever one or more males in the patch remain uninspected; this threshold drops when inspecting the last male in the patch, so returns may occur only then and are never to a male in a previously inspected patch. With non-zero within-patch return costs, such a two-threshold rule still performs extremely well, but a more gradual decline in acceptance threshold is optimal. Inability to return at all need not decrease performance by much. The acceptance threshold should also decline if it gets harder to discover the last males in a patch. Optimal strategies become more complex when mean male quality varies systematically between patches or years, and females estimate this in a Bayesian manner through inspecting male qualities. It can then be optimal to switch patch before inspecting all males on a patch, or, exceptionally, to return to an earlier patch. We compare performance of various rules of thumb in these environments and in ones without a patch structure. A two-threshold rule performs excellently, as do various simplifications of it. The best-of-N rule outperforms threshold rules only in non-patchy environments with between-year quality variation. The cutoff rule performs poorly.

Dynamic endocrine responses to stress: evidence for energetic constraints and status dependence in breeding male green turtles.

PubMed

Jessop, Tim S; Knapp, Rosemary; Whittier, Joan M; Limpus, Col J

2002-03-01

During reproduction, male vertebrates may exhibit a continuum of interactions between sex and adrenal steroids during stressful events, the outcome of which may be important in either reducing or promoting male reproductive success. We studied adult male green turtles (Chelonia mydas) to examine if they altered plasma corticosterone (CORT) and androgen levels in response to a standardized capture/restraint stressor as potential mechanisms to maintain reproductive activity during stressful events. At the population level, we found that migrant breeding males had a significantly smaller CORT response to the capture/restraint stressor compared to nonbreeding males and that this decreased response coincided with the generally poorer body condition of migrant breeders. In contrast, plasma androgen levels decreased significantly in response to the capture/restraint stressor in migrant breeding males, but not in nonbreeding and pre-migrant breeding males. For individual migrant breeding males, the magnitude of their CORT and androgen responses to the capture/restraint stressor was highly correlated with their body condition and body length, respectively. Our results demonstrate that male green turtles exhibit complex interactions in their endocrine responses to a capture/restraint stressor and that variation in these interactions is associated with differences in males' reproductive, energetic, and physical state. We hypothesize that interplay between physical status and plasma hormone responses to stressors could have important consequences for male green turtle reproduction.

Sex differences in autism: a resting-state fMRI investigation of functional brain connectivity in males and females.

PubMed

Alaerts, Kaat; Swinnen, Stephan P; Wenderoth, Nicole

2016-06-01

Autism spectrum disorders (ASD) are far more prevalent in males than in females. Little is known however about the differential neural expression of ASD in males and females. We used a resting-state fMRI-dataset comprising 42 males/42 females with ASD and 75 male/75 female typical-controls to examine whether autism-related alterations in intrinsic functional connectivity are similar or different in males and females, and particularly whether alterations reflect 'neural masculinization', as predicted by the Extreme Male Brain theory. Males and females showed a differential neural expression of ASD, characterized by highly consistent patterns of hypo-connectivity in males with ASD (compared to typical males), and hyper-connectivity in females with ASD (compared to typical females). Interestingly, patterns of hyper-connectivity in females with ASD reflected a shift towards the (high) connectivity levels seen in typical males (neural masculinization), whereas patterns of hypo-connectivity observed in males with ASD reflected a shift towards the (low) typical feminine connectivity patterns (neural feminization). Our data support the notion that ASD is a disorder of sexual differentiation rather than a disorder characterized by masculinization in both genders. Future work is needed to identify underlying factors such as sex hormonal alterations that drive these sex-specific neural expressions of ASD. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Is Male Androphilia a Context-Dependent Cross-Cultural Universal?

PubMed

Hames, Raymond; Garfield, Zachary; Garfield, Melissa

2017-01-01

The cross-cultural ethnographic literature has traditionally used the label male "homosexuality" to describe sexual relationships between biological males without considering whether or not the concept encompasses primary sexual attraction to adult males. Although male androphilia seems to be found in all national populations, its universal existence in tribal populations has been questioned. Our goal is to review previous cross-cultural classifications and surveys of male same sex behavior to present a system that does justice to its varied expressions, especially as it is informed by contemporary sexuality research. Previous comparative research does not effectively distinguish male same sex behavior from male androphilia. Using the standard cross-cultural sample (SCCS) as a sampling frame and the ethnographic sources in the human relations area files and elsewhere, we present distributional data on various forms of male same sex behavior. The SCCS is useful because it is designed to be representative of all historically known social formations and the sample is designed to reduce similarities as a consequence of common descent or historical origin as well as reduce the probability of diffusion of sociocultural practices from one culture to another. Our results show that male same sex behavior as well as male androphilia is much more common than previously estimated in the SCCS. With our findings, we make an argument that male androphilia is a context-dependent cross-cultural universal.

Hematologic Profile and Semen Quality of Male Timor Deer (Rusa timorensis) at Various Hierarchies

NASA Astrophysics Data System (ADS)

Samsudewa, D.; Capitan, S. S.; Sevilla, C. C.; Vega, R. S. A.; Ocampo, P. P.

2018-02-01

The aim of this research was to observe hematologic profile i.e. erythrocyte count, hemoglobin and hematocrit and semen quality, i.e. semen volume, sperm motility and sperm abnormality of α-male, β-male and subordinate male Timor deer raised under captivity. Twelve males (51 ± 6 months old; 68.29 ± 8.41kg body weight) at similar antler stages were use in this study. Before and after 43 days of establishment of dominance hierarchy blood were sampled after sedation for erythrocyte count, hemoglobin (mg/dL), and hematocrit (%). Likewise, semen was collected using electroejaculator and were analyzed for semen volume (ml), sperm motility (%) and sperm abnormality (%) to compare male deer at various heirarchies. Wilcoxon signed ranks test and Kruskal-Wallis H test of non-parametric analysis was done. Significant difference was tested with Mann-Whitney U test. The results showed that highest count of erythrocyte shown on α and β-male (1.60 million per µL). The highest increase in hematocrit was observed in β-male (5%) and then followed by S2-male (4%). S2-male had the highest increase in hemoglobin (0.13 g/dL). The highest increase in semen volume was observed in α -male (0.75 ml). Social stress affected negatively the sperm motility and abnormality (P<0.05). The highest decrease was observed in S2-male.

Factors Affecting Pheromone Production by the Pepper Weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) and Collection Efficiency

PubMed Central

Eller, Fred J.; Palmquist, Debra E.

2014-01-01

Several factors affecting pheromone production by male pepper weevils, Anthonomus eugenii Cano (Coleoptera: Curculionidae) as well as collection efficiency were investigated. Factors studied included: porous polymer adsorbents (Tenax versus Super Q), male age, time of day, male density, and male diet. Super Q was found to be a superior adsorbent for the male-produced alcohols and geranic acid as well as the plant-produced E-β-ocimene. Pheromone production increased with male age up to about age 15 days old and then tapered off. Male pepper weevils produced the highest amount of pheromone between noon and 2 pm (i.e., 4 to 6 h after “lights on”) and were producing ca. 800 ng/h during this period. Thereafter, pheromone production decreased and was extremely low during the scotophase (i.e., ca. 12 ng/h). Male pepper weevil density had a significant effect on both release rate and pheromone composition. Pheromone production on a per male basis was highest for individual males and the percentage of geranic acid in the blend was lowest for individual males. Male pepper weevils produced only extremely low amounts of pheromone when feeding on artificial diet; however, they produced very high amounts when on fresh peppers. Together, this information will be useful in designing better attractant lures for pepper weevils. PMID:26462948

Identifying individual male reproductive consistency in Drosophila melanogaster: The importance of controlling female behaviour.

PubMed

Balaban-Feld, Jesse; Valone, Thomas J

2017-09-01

Work on the repeatability of reproductive behaviour has mainly focused on the consistency of female preferences. We characterised the consistency of individual male Drosophila melanogaster reproductive behaviour in two experiments. In the first experiment, we allowed males to interact with a pair of live females that differed in body size. We then controlled female behaviour in a second experiment by examining the courtship behaviour of individual males interacting with a pair of decapitated females that varied in body size. In both experiments, we examined the consistency of individual male reproductive behaviour across two repeated trials on the same day. Males did not exhibit a courtship preference for the larger female in either experiment, but, in experiment 1, males did exhibit post-copulatory choice by copulating for longer durations with the large female, and males that mated with the same type of female in both trials exhibited repeatable behaviour. In general, we found weak evidence of consistent male courtship behaviour in the presence of behaving females. However, when female behaviour was controlled in experiment 2, we found that male courtship behaviour was highly repeatable. These results indicate that individual male D. melanogaster exhibit consistent reproductive behaviour and demonstrate the importance of controlling female behaviour when attempting to characterise the repeatability of male reproductive behaviour. Copyright © 2017 Elsevier B.V. All rights reserved.

Failed sperm development as a reproductive isolating barrier between species.

PubMed

Wünsch, Lisa K; Pfennig, Karin S

2013-01-01

Hybrid male sterility is a common reproductive isolating barrier between species. Yet, little is known about the actual developmental causes of this phenomenon, especially in naturally hybridizing species. We sought to evaluate the developmental causes of hybrid male sterility, using spadefoot toads as our study system. Plains spadefoot toads (Spea bombifrons) and Mexican spadefoot toads (S. multiplicata) hybridize where they co-occur in the southwestern USA. Hybrids are viable, but hybrid males suffer reduced fertility. We compared testes size and developmental stages of sperm cell maturation between hybrid males and males of each species. We found that testes of hybrid males did not differ in mean size from pure-species males. However, hybrids showed a greater range of within-individual variation in testes size than pure-species males. Moreover, although hybrids produced similar numbers of early stage sperm cells, hybrids produced significantly fewer mature spermatozoids than pure-species males. Interestingly, an introgressed individual produced numbers of live sperm comparable to pure-species males, but the majority of these sperm cells were abnormally shaped and non-motile. These results indicate that hybrid incompatibilities in late sperm development serve as a reproductive isolating barrier between species. The nature of this breakdown highlights the possibilities that hybrid males may vary in fertility and that fertility could possibly be recovered in introgressed males. © 2013 Wiley Periodicals, Inc.

Low Testosterone Correlates with Delayed Development in Male Orangutans

PubMed Central

Emery Thompson, Melissa; Zhou, Amy; Knott, Cheryl D.

2012-01-01

Male orangutans (Pongo spp.) display an unusual characteristic for mammals in that some adult males advance quickly to full secondary sexual development while others can remain in an adolescent-like form for a decade or more past the age of sexual maturity. Remarkably little is understood about how and why differences in developmental timing occur. While fully-developed males are known to produce higher androgen levels than arrested males, the longer-term role of steroid hormones in male life history variation has not been examined. We examined variation in testosterone and cortisol production among 18 fully-developed (“flanged”) male orangutans in U.S. captive facilities. Our study revealed that while testosterone levels did not vary significantly according to current age, housing condition, and species origin, males that had undergone precocious development had higher testosterone levels than males that had experienced developmental arrest. While androgen variation had previously been viewed as a state-dependent characteristic of male developmental status, our study reveals that differences in the physiology of early and late developing males are detectable long past the developmental transition and may instead be trait-level characteristics associated with a male’s life history strategy. Further studies are needed to determine how early in life differences in testosterone levels emerge and what consequences this variation may have for male behavioral strategies. PMID:23077585

Certainty of paternity and paternal investment in eastern bluebirds and tree swallows

USGS Publications Warehouse

Kempenaers, Bart; Lanctot, Richard B.; Robertson, Raleigh J.

1998-01-01

Extra-pair paternity is common in many socially monogamous passerine birds with biparental care. Thus, males often invest in offspring to which they are not related. Models of optimal parental investment predict that, under certain assumptions, males should lower their investment in response to reduced certainty of paternity. We attempted to reduce certainty of paternity experimentally in two species, the eastern bluebird, Sialia sialis, and the tree swallow, Tachycineta bicolor, by temporarily removing fertile females on two mornings during egg laying. In both species, experimental males usually attempted to copulate with the female immediately after her reappearance, suggesting that they experienced the absence of their mate as a threat to their paternity. Experimental males copulated at a significantly higher rate than control males. However, contrary to the prediction of the model, experimental males did not invest less than control males in their offspring. There was no difference between experimental and control nests in the proportion of male feeds, male and female feeding rates, nestling growth and nestling condition and size at age 14 days. We argue that females might have restored the males’ confidence in paternity after the experiment by soliciting or accepting copulations. Alternatively, males may not reduce their effort, because the fitness costs to their own offspring may outweigh the benefits for the males, at least in populations where females cannot fully compensate for reduced male investment.

21 CFR 876.5160 - Urological clamp for males.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Urological clamp for males. 876.5160 Section 876...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5160 Urological clamp for males. (a) Identification. A urological clamp for males is a device used to close the urethra of a male to...

Student Evaluations of College Professors: Are Female and Male Professors Rated Differently?

ERIC Educational Resources Information Center

Basow, Susan A.; Silberg, Nancy T.

1987-01-01

Over 1,000 undergraduates evaluated 16 male and female professors in terms of teaching effectiveness and sex-typed characteristics. Male students gave female professors significantly poorer ratings than male professors on the six teaching evaluation measures. Female students evaluated female professors less favorably than male professors on three…

The Inexpressive Male: Functional-Conflict and Role Theory as Contrasting Explanations.

ERIC Educational Resources Information Center

Balswick, Jack

1979-01-01

Compares functional-conflict and role theory perspectives in their ability to explain male inexpressiveness. The role theory approach incorporates the individual and the social structure in explaining male inexpressiveness. Change in male expressiveness can be expected if males are encouraged to devote more time and energy to emotionally laden…

Community Violence, Social Support Networks, Ethnic Group Differences, and Male Perpetration of Intimate Partner Violence

ERIC Educational Resources Information Center

Raghavan, Chitra; Rajah, Valli; Gentile, Katie; Collado, Lillian; Kavanagh, Ann Marie

2009-01-01

The authors examined how witnessing community violence influenced social support networks and how these networks were associated with male-to-female intimate partner violence (IPV) in ethnically diverse male college students. The authors assessed whether male social support members themselves had perpetrated IPV (male network violence) and whether…

Graduating Black Males: A Generic Qualitative Study

ERIC Educational Resources Information Center

Bell, Edward E.

2014-01-01

Black males face a difficult educational battle. Across America, graduation statistics for Black males are sobering. The purpose of this study was to explore why Black males drop out of school and to examine the current employment status of the study participants. The research took place in rural North Carolina. Fifteen Black American male high…

Perceptions of Credibility of Male and Female Syndicated Political Columnists.

ERIC Educational Resources Information Center

Andsager, Julie L.

1990-01-01

Examines perceptions of the credibility of male and female syndicated political columnists. Finds that college students exhibited little prejudice against female versus male bylines in political interpretive columns. Finds a small tendency for male readers to evaluate male bylines higher in stereotypical ways, but female readers do not do this.…

Sexy faces in a male paper wasp.

PubMed

de Souza, André Rodrigues; Alberto Mourão Júnior, Carlos; do Nascimento, Fabio Santos; Lino-Neto, José

2014-01-01

Sexually selected signals are common in many animals, though little reported in social insects. We investigated the occurrence of male visual signals mediating the dominance relationships among males and female choice of sexual partner in the paper wasp Polistes simillimus. Males have three conspicuous, variable and sexually dimorphic traits: black pigmentation on the head, a pair of yellow abdominal spots and body size differences. By conducting behavioral assays, we found that none of the three visual traits are associated with male-male dominance relationship. However, males with higher proportion of black facial pigmentation and bigger yellow abdominal spots are more likely chosen as sexual partners. Also, after experimentally manipulating the proportion of black pigment on males' face, we found that females may evaluate male facial coloration during the choice of a sexual partner. Thus, the black pigmentation on P. simillimus male's head appears to play a role as a sexually selected visual signal. We suggest that sexual selection is a common force in Polistes and we highlight the importance of this group as a model for the study of visual communication in insects.

Sexual cannibalism increases male material investment in offspring: quantifying terminal reproductive effort in a praying mantis

PubMed Central

Brown, William D.; Barry, Katherine L.

2016-01-01

Models of the evolution of sexual cannibalism argue that males may offset the cost of cannibalism if components of the male body are directly allocated to the eggs that they fertilize. We tested this idea in the praying mantid Tenodera sinensis. Males and females were fed differently radiolabelled crickets and allowed to mate. Half of the pairs progressed to sexual cannibalism and we prevented cannibalism in the other half. We assess the relative allocation of both male-derived somatic materials and ejaculate materials into the eggs and soma of the female. Our results show that male somatic investment contributes to production of offspring. The eggs and reproductive tissues of cannibalistic females contained significantly more male-derived amino acids than those of non-cannibalistic females, and there was an increase in the number of eggs produced subsequent to sexual cannibalism. Sexual cannibalism thus increases male material investment in offspring. We also show that males provide substantial investment via the ejaculate, with males passing about 25% of their radiolabelled amino acids to females via the ejaculate even in the absence of cannibalism. PMID:27358366

Female Preference for Sympatric vs. Allopatric Male Throat Color Morphs in the Mesquite Lizard (Sceloporus grammicus) Species Complex

PubMed Central

Bastiaans, Elizabeth; Bastiaans, Mary Jane; Morinaga, Gen; Castañeda Gaytán, José Gamaliel; Marshall, Jonathon C.; Bane, Brendan; de la Cruz, Fausto Méndez; Sinervo, Barry

2014-01-01

Color polymorphic sexual signals are often associated with alternative reproductive behaviors within populations, and the number, frequency, or type of morphs present often vary among populations. When these differences lead to assortative mating by population, the study of such polymorphic taxa may shed light on speciation mechanisms. We studied two populations of a lizard with polymorphic throat color, an important sexual signal. Males in one population exhibit orange, yellow, or blue throats; whereas males in the other exhibit orange, yellow, or white throats. We assessed female behavior when choosing between allopatric and sympatric males. We asked whether females discriminated more when the allopatric male was of an unfamiliar morph than when the allopatric male was similar in coloration to the sympatric male. We found that female rejection of allopatric males relative to sympatric males was more pronounced when males in a pair were more different in throat color. Our findings may help illuminate how behavioral responses to color morph differences between populations with polymorphic sexual signals contribute to reproductive isolation. PMID:24718297

Male but not female olfaction is crucial for intermolt mating in European lobsters (Homarus gammarus L.).

PubMed

Skog, Malin

2009-02-01

Chemical signals are common in most crustacean social interactions and are often perceived via chemosensory (olfactory) organs on the first antenna. Intermolt courtship behaviors and mating were investigated in size-matched pairs of intermolt European lobsters (Homarus gammarus) where the olfactory receptors of either the male or the female were lesioned with distilled water (olfactory ablation) or seawater (control). Matings or advanced male courtship behaviors (mounting and turning) were common in seawater controls and olfactory-ablated females. In contrast, when male olfaction was ablated with distilled water, there was not a single mating, and the only male courtship behaviors seen were a few very brief and unsuccessful mounting attempts. Individual females mated up to 5 times with different males, showing that previously inseminated females were still attractive to males. Thus, male but not female olfaction is crucial for intermolt mating in H. gammarus, indicating the presence of a female sex pheromone during the entire female molt cycle, not only at the time of molting. Female sex discrimination may be based on other cues from the male in combination with typical male behaviors.

Social context-dependent modification of courtship behaviour in Drosophila prolongata

PubMed Central

Setoguchi, Shiori; Kudo, Ayumi; Takanashi, Takuma; Ishikawa, Yukio; Matsuo, Takashi

2015-01-01

Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform ‘leg vibration’, in which a male vibrates the female's body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to ‘rubbing’, which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration. PMID:26538591

Social context-dependent modification of courtship behaviour in Drosophila prolongata.

PubMed

Setoguchi, Shiori; Kudo, Ayumi; Takanashi, Takuma; Ishikawa, Yukio; Matsuo, Takashi

2015-11-07

Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform 'leg vibration', in which a male vibrates the female's body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to 'rubbing', which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration. © 2015 The Author(s).

Eavesdropping and signal matching in visual courtship displays of spiders

PubMed Central

Clark, David L.; Roberts, J. Andrew; Uetz, George W.

2012-01-01

Eavesdropping on communication is widespread among animals, e.g. bystanders observing male–male contests, female mate choice copying and predator detection of prey cues. Some animals also exhibit signal matching, e.g. overlapping of competitors' acoustic signals in aggressive interactions. Fewer studies have examined male eavesdropping on conspecific courtship, although males could increase mating success by attending to others' behaviour and displaying whenever courtship is detected. In this study, we show that field-experienced male Schizocosa ocreata wolf spiders exhibit eavesdropping and signal matching when exposed to video playback of courting male conspecifics. Male spiders had longer bouts of interaction with a courting male stimulus, and more bouts of courtship signalling during and after the presence of a male on the video screen. Rates of courtship (leg tapping) displayed by individual focal males were correlated with the rates of the video exemplar to which they were exposed. These findings suggest male wolf spiders might gain information by eavesdropping on conspecific courtship and adjust performance to match that of rivals. This represents a novel finding, as these behaviours have previously been seen primarily among vertebrates. PMID:22219390

Sexy Faces in a Male Paper Wasp

PubMed Central

de Souza, André Rodrigues; Alberto Mourão Júnior, Carlos; Santos do Nascimento, Fabio; Lino-Neto, José

2014-01-01

Sexually selected signals are common in many animals, though little reported in social insects. We investigated the occurrence of male visual signals mediating the dominance relationships among males and female choice of sexual partner in the paper wasp Polistes simillimus. Males have three conspicuous, variable and sexually dimorphic traits: black pigmentation on the head, a pair of yellow abdominal spots and body size differences. By conducting behavioral assays, we found that none of the three visual traits are associated with male-male dominance relationship. However, males with higher proportion of black facial pigmentation and bigger yellow abdominal spots are more likely chosen as sexual partners. Also, after experimentally manipulating the proportion of black pigment on males' face, we found that females may evaluate male facial coloration during the choice of a sexual partner. Thus, the black pigmentation on P. simillimus male's head appears to play a role as a sexually selected visual signal. We suggest that sexual selection is a common force in Polistes and we highlight the importance of this group as a model for the study of visual communication in insects. PMID:24849073

Male antenna morphology and its effect on scramble competition in false garden mantids

NASA Astrophysics Data System (ADS)

Jayaweera, Anuradhi; Barry, Katherine L.

2017-10-01

Well-developed antennae are crucial for many insects, but especially for scramble competitors, who race to find their mates using female sex cues. In these systems, the ability of males to locate females quickly is thought to be under strong selection. A rarely tested assumption is that males with more sensory structures are able to locate females faster. In the present study, we used the false garden mantid Pseudomantis albofimbriata to investigate male antennal morphology and its effect on male efficiency in finding a mate. We used scanning electron microscopy to describe the major sensilla types and their arrangement along the length of male antennae. We also conducted field enclosure trials relating male antennal morphology to scramble competition in this system. We identified six different types of antennal sensilla (cheatic, trichoid, basiconic, grooved peg, ceolocapitular and campaniform) on male P. albofimbriata antennae. As expected, males who had more trichoid sensilla located females quicker than did males with fewer sensilla. Results of the current study suggest that antenna morphology plays a significant role in mate location and hence scramble competition in the P. albofimbriata mating system.

Review of bulimia nervosa in males.

PubMed

Carlat, D J; Camargo, C A

1991-07-01

The authors describe the distribution of bulimia nervosa among males and identify characteristics that distinguish male bulimics from their female counterparts. Potential references were identified through an English-language literature search using MEDLINE (1966 to April 1990) and through extensive manual searching of textbooks and reviews. All published works with original data or hypotheses concerning bulimia in males were included. Bulimia affects approximately 0.2% of adolescent boys and young adult men, and males account for 10%-15% of all bulimic subjects identified in community-based studies. Compared to their female counterparts, male bulimics appear to have a later age of onset; higher prevalences of premorbid obesity, homosexuality, and asexuality; and less concern with strict weight control. These findings are discussed from biological, psychological, and cultural perspectives to develop a fuller understanding of the pathogenesis of bulimia in males. Bulimia in males has received relatively little attention in the literature. Future research should focus on more rigorous analytic studies that include matched comparison groups of female bulimic and male nonbulimic subjects. Such studies would not only benefit male bulimics but might provide insight into the nature of bulimia in both sexes.

Highly Competitive Reindeer Males Control Female Behavior during the Rut

PubMed Central

Body, Guillaume; Weladji, Robert B.; Holand, Øystein; Nieminen, Mauri

2014-01-01

During the rut, female ungulates move among harems or territories, either to sample mates or to avoid harassment. Females may be herded by a male, may stay with a preferred male, or aggregate near a dominant male to avoid harassment from other males. In fission-fusion group dynamics, female movement is best described by the group’s fission probability, instead of inter-harem movement. In this study, we tested whether male herding ability, female mate choice or harassment avoidance influence fission probability. We recorded group dynamics in a herd of reindeer Rangifer tarandus equipped with GPS collars with activity sensors. We found no evidence that the harassment level in the group affected fission probability, or that females sought high rank (i.e. highly competitive and hence successful) males. However, the behavior of high ranked males decreased fission probability. Male herding activity was synchronous with the decrease of fission probability observed during the rut. We concluded that male herding behavior stabilized groups, thereby increasing average group size and consequently the opportunity for sexual selection. PMID:24759701

Male antenna morphology and its effect on scramble competition in false garden mantids.

PubMed

Jayaweera, Anuradhi; Barry, Katherine L

2017-08-23

Well-developed antennae are crucial for many insects, but especially for scramble competitors, who race to find their mates using female sex cues. In these systems, the ability of males to locate females quickly is thought to be under strong selection. A rarely tested assumption is that males with more sensory structures are able to locate females faster. In the present study, we used the false garden mantid Pseudomantis albofimbriata to investigate male antennal morphology and its effect on male efficiency in finding a mate. We used scanning electron microscopy to describe the major sensilla types and their arrangement along the length of male antennae. We also conducted field enclosure trials relating male antennal morphology to scramble competition in this system. We identified six different types of antennal sensilla (cheatic, trichoid, basiconic, grooved peg, ceolocapitular and campaniform) on male P. albofimbriata antennae. As expected, males who had more trichoid sensilla located females quicker than did males with fewer sensilla. Results of the current study suggest that antenna morphology plays a significant role in mate location and hence scramble competition in the P. albofimbriata mating system.

Low level of polyandry constrains phenotypic plasticity of male body size in mites.

PubMed

Schausberger, Peter; Walzer, Andreas; Murata, Yasumasa; Osakabe, Masahiro

2017-01-01

Polyandry, i.e. females mating with multiple males, is more common than previously anticipated and potentially provides both direct and indirect fitness benefits to females. The level of polyandry (defined by the lifetime number of male mates of a female) is an important determinant of the occurrence and intensity of sexual selection acting on male phenotypes. While the forces of sexual selection acting on phenotypic male traits such as body size are relatively well understood, sexual selection acting on phenotypic plasticity of these traits is unexplored. We tackled this issue by scrutinizing the link between polyandry and phenotypic plasticity of male body size in two sympatric plant-inhabiting predatory mite species, Phytoseiulus persimilis and Neoseiulus californicus. These two species are similar in life history, ecological niche requirements, mating behavior, polygyny and female body size plasticity but strikingly differ in the level of both polyandry and phenotypic plasticity of male body size (both lower in P. persimilis). We hypothesized that deviations from standard body size, i.e. the size achieved under favorable conditions, incur higher costs for males in the less polyandrous P. persimilis. To test our hypotheses, we conducted two experiments on (i) the effects of male body size on spermatophore transfer in singly mating females and (ii) the effects of mate sequence (switching the order of standard-sized and small males) on mating behavior and paternity success in doubly mating females. In P. persimilis but not N. californicus, small males transferred fewer but larger spermatophores to the females; in both species, females re-mated more likely with standard-sized following small than small following standard-sized males; in P. persimilis, first standard-sized males sired a higher proportion of offspring produced after re-mating by the female than first small males, whereas in N. californicus the paternity success of small and standard-sized males was independent of the mating sequence. Based on our results and pertinent previous studies, which showed that females of P. persimilis, but not N. californicus, prefer mating with standard-sized over small males and allow them fertilizing more eggs, the lack of interspecific difference in female body size plasticity, and the absence of any clue pointing at a role of natural selection, we suggest that the interspecific difference in male body size plasticity is sexually selected. Our study provides an indication of sexual selection constraining plasticity of male phenotypes, suggesting that the level of polyandry may be an important co-determinant of the level of phenotypic plasticity of male body size.

Low level of polyandry constrains phenotypic plasticity of male body size in mites

PubMed Central

Walzer, Andreas; Murata, Yasumasa; Osakabe, Masahiro

2017-01-01

Polyandry, i.e. females mating with multiple males, is more common than previously anticipated and potentially provides both direct and indirect fitness benefits to females. The level of polyandry (defined by the lifetime number of male mates of a female) is an important determinant of the occurrence and intensity of sexual selection acting on male phenotypes. While the forces of sexual selection acting on phenotypic male traits such as body size are relatively well understood, sexual selection acting on phenotypic plasticity of these traits is unexplored. We tackled this issue by scrutinizing the link between polyandry and phenotypic plasticity of male body size in two sympatric plant-inhabiting predatory mite species, Phytoseiulus persimilis and Neoseiulus californicus. These two species are similar in life history, ecological niche requirements, mating behavior, polygyny and female body size plasticity but strikingly differ in the level of both polyandry and phenotypic plasticity of male body size (both lower in P. persimilis). We hypothesized that deviations from standard body size, i.e. the size achieved under favorable conditions, incur higher costs for males in the less polyandrous P. persimilis. To test our hypotheses, we conducted two experiments on (i) the effects of male body size on spermatophore transfer in singly mating females and (ii) the effects of mate sequence (switching the order of standard-sized and small males) on mating behavior and paternity success in doubly mating females. In P. persimilis but not N. californicus, small males transferred fewer but larger spermatophores to the females; in both species, females re-mated more likely with standard-sized following small than small following standard-sized males; in P. persimilis, first standard-sized males sired a higher proportion of offspring produced after re-mating by the female than first small males, whereas in N. californicus the paternity success of small and standard-sized males was independent of the mating sequence. Based on our results and pertinent previous studies, which showed that females of P. persimilis, but not N. californicus, prefer mating with standard-sized over small males and allow them fertilizing more eggs, the lack of interspecific difference in female body size plasticity, and the absence of any clue pointing at a role of natural selection, we suggest that the interspecific difference in male body size plasticity is sexually selected. Our study provides an indication of sexual selection constraining plasticity of male phenotypes, suggesting that the level of polyandry may be an important co-determinant of the level of phenotypic plasticity of male body size. PMID:29190832

The occurrence of female-to-male partner violence among male intimate partner violence offenders mandated to treatment: a brief research report.

PubMed

Crane, Cory A; Hawes, Samuel W; Mandel, Dolores L; Easton, Caroline J

2014-01-01

Little is known about the perceived perpetration of female-to-male intimate partner violence by victims of male offenders mandated to treatment. Sixty-eight male perpetrators of partner violence completed measures of dyadic violent and aggressive responding at intake and at a 12-week follow-up. Approximately 20% of male offenders reported partner violence perpetration and 30% reported victimization with bidirectional violence as the most common configuration of couple violence. Maladaptive responses to conflict were prevalent across partners. Significant and highly correlated reductions in aversive behaviors were detected across the assessment period for both males and their female partners. Results are interpreted within the context of motivational models of female-to-male partner violence and current treatment approaches.

Intruder colour and light environment jointly determine how nesting male stickleback respond to simulated territorial intrusions.

PubMed

Bolnick, Daniel I; Hendrix, Kimberly; Jordan, Lyndon Alexander; Veen, Thor; Brock, Chad D

2016-08-01

Variation in male nuptial colour signals might be maintained by negative frequency-dependent selection. This can occur if males are more aggressive towards rivals with locally common colour phenotypes. To test this hypothesis, we introduced red or melanic three-dimensional printed-model males into the territories of nesting male stickleback from two optically distinct lakes with different coloured residents. Red-throated models were attacked more in the population with red males, while melanic models were attacked more in the melanic male lake. Aggression against red versus melanic models also varied across a depth gradient within each lake, implying that the local light environment also modulated the strength of negative frequency dependence acting on male nuptial colour. © 2016 The Author(s).

The Occurrence of Female-to-Male Partner Violence Among Male Intimate Partner Violence Offenders Mandated to Treatment: A Brief Research Report

PubMed Central

Crane, Cory A.; Hawes, Samuel W.; Mandel, Dolores; Easton, Caroline J.

2014-01-01

Little is known about the perceived perpetration of female-to-male intimate partner violence by victims of male offenders mandated to treatment. Sixty-eight male perpetrators of partner violence completed measures of dyadic violent and aggressive responding at intake and at a 12 week follow-up. Approximately 20% of male offenders reported partner violence perpetration and 30% reported victimization with bi-directional violence as the most common configuration of couple violence. Maladaptive responses to conflict were prevalent across partners. Significant and highly correlated reductions in aversive behaviors were detected across the assessment period for both males and their female partners. Results are interpreted within the context of motivational models of female-to-male partner violence and current treatment approaches. PMID:25750479

Fishery Induces Sperm Depletion and Reduction in Male Reproductive Potential for Crab Species under Male-Biased Harvest Strategy

PubMed Central

Pardo, Luis Miguel; Rosas, Yenifer; Fuentes, Juan Pablo; Riveros, Marcela Paz; Chaparro, Oscar Roberto

2015-01-01

Sperm depletion in males can occur when polygynous species are intensively exploited under a male-biased management strategy. In fisheries involving crabs species, the effects of this type of management on the reproductive potential is far from being understood. This study tests whether male-biased management of the principal Chilean crab fishery is able to affect the potential capacity of Metacarcinus edwardsii males to transfer sperm to females. Five localities in southern Chile, recording contrasting crab fishery landing, were selected to assess the potential of sperm depletion triggered by fishery. Seasonally, male crabs from each locality were obtained. Dry weight and histological condition of vasa deferentia and the Vaso-Somatic Index (VSI) were determined in order to use them as proxies for sperm depletion and male reproductive condition. A manipulative experiment was performed in the laboratory to estimate vasa deferentia weight and VSI from just-mated males in order to obtain a reference point for the potential effects of the fishery on sperm reserves. Sperm storage capacity is significantly affected by fisheries; during the mating season vasa deferentia from localities with low fishery intensity were heavier than those from high intensity fisheries, and these differences were even more evident in large males. Histological section showed that this disparity in vasa deferentia weight was explained principally by differences in the quantity of spermatophores rather than other seminal material. VSI was always higher in males from localities with low fishery intensity. Males from localities with high fishery intensity showed little capacity to recover sperm reserves and the VSI of these males remained below the values of the just-mated males. Detriment in the capacity of males to transfer sperm is the first step to sperm limitation in an exploited population, thus detection of sperm depletion can be an alert to introduce changes in the current management of crabs. PMID:25768728

The Function of Anal Fin Egg-Spots in the Cichlid Fish Astatotilapia burtoni

PubMed Central

Theis, Anya; Salzburger, Walter; Egger, Bernd

2012-01-01

Color and pigmentation patterns of animals are often targets of sexual selection because of their role in communication. Although conspicuous male traits are typically implicated with intersexual selection, there are examples where sex-specific displays play a role in an intrasexual context, e.g. when they serve as signals for aggression level and/or status. Here, we focus on the function of a conspicuous male ornament in the most species-rich tribe of cichlid fishes, the haplochromines. A characteristic feature of these ca. 1500 species are so-called egg-spots in form of ovoid markings on the anal fins of males, which are made up of carotenoid based pigment cells. It has long been assumed that these yellow, orange or reddish egg-spots play an important role in the courtship and spawning behavior of these maternal mouth-brooding fishes by mimicking the eggs of a conspecific female. The exact function of egg-spots remains unknown, however, and there are several hypotheses about their mode of action. To uncover the function of this cichlid-specific male ornament, we used female mate choice experiments and a male aggression test in the haplochromine species Astatotilapia burtoni. We manipulated the number and arrangement of egg-spots on the anal fins of males, or removed them entirely, and tested (1) female preference with visual contact only using egg-traps, (2) female preference with free contact using paternity testing with microsatellites and (3) male aggression. We found that females did not prefer males with many egg-spots over males with fewer egg-spots and that females tended to prefer males without egg-spots over males with egg-spots. Importantly, males without egg-spots sired clutches with the same fertilization rate as males with egg-spots. In male aggression trials, however, males with fewer egg-spots received significantly more attacks, suggesting that egg-spots are an important signal in intrasexual communication. PMID:22242184

Adolescent male chimpanzees do not form a dominance hierarchy with their peers.

PubMed

Sandel, Aaron A; Reddy, Rachna B; Mitani, John C

2017-01-01

Dominance hierarchies are a prominent feature of the lives of many primate species. These hierarchies have important fitness consequences, as high rank is often positively correlated with reproduction. Although adult male chimpanzees strive for status to gain fitness benefits, the development of dominance relationships is not well understood. While two prior studies found that adolescent males do not display dominance relationships with peers, additional research at Ngogo in Kibale National Park, Uganda, indicates that adolescents there form a linear dominance hierarchy. These conflicting findings could reflect different patterns of rank acquisition across sites. An alternate possibility arises from a recent re-evaluation of age estimates at Ngogo and suggests that the report describing decided dominance relationships between adolescent males may have been due to the accidental inclusion of young adult males in the sample. To investigate these issues, we conducted a study of 23 adolescent male chimpanzees of known age during 12 months at Ngogo. Adolescent male chimpanzees exchanged pant grunts, a formal signal of submission, only 21 times. Recipients of pant grunts were late adolescent males, ranging between 14 and 16 years old. In contrast, younger adolescent males never received pant grunts from other males. Aggression between adolescent males was also rare. Analysis of pant grunts and aggressive interactions did not produce a linear dominance hierarchy among adolescent males. These data indicate that adolescent male chimpanzees do not form decided dominance relationships with their peers and are consistent with the hypothesis that the hierarchy described previously at Ngogo resulted from inaccurate age estimates of male chimpanzees. Because dominance relationships develop before adulthood in other primates, our finding that adolescent male chimpanzees do not do so is surprising. We offer possible explanations for why this is the case and suggest future studies that may help clarify the matter.

How to Be a Male at Different Elevations: Ecology of Intra-Sexual Segregation in the Trawling Bat Myotis daubentonii

PubMed Central

Nardone, Valentina; Cistrone, Luca; Di Salvo, Ivy; Ariano, Alessandro; Migliozzi, Antonello; Allegrini, Claudia; Ancillotto, Leonardo; Fulco, Antonio; Russo, Danilo

2015-01-01

Intra-sexual segregation is a form of social segregation widespread among vertebrates. In the bat Myotis daubentonii, males are disproportionately abundant at higher elevations, while females are restricted to lower altitude. Intra-male segregation is also known to occur yet its ecological and behavioural determinants are unclear. We studied male segregation along a river in Central Italy where we tested the following predictions: 1. Upstream ( > 1000 m a.s.l.) males will rely on scarcer prey; 2. To deal with this limitation and exploit a cooler roosting environment, they will employ more prolonged and deeper torpor than downstream (< 900 m a.s.l.) males; 3. Body condition will be better in downstream males as they forage in more productive areas; 4. To cope with less predictable foraging opportunities, upstream males will use more habitat types. Consistent with our predictions, we found that prey were less common at higher altitudes, where bats exhibited prolonged and deeper torpor. Body condition was better in downstream males than in upstream males but not in all summer months. This result reflected a decrease in downstream males’ body condition over the season, perhaps due to the energy costs of reduced opportunities to use torpor and/or intraspecific competition. Downstream males mainly foraged over selected riparian vegetation whereas upstream males used a greater variety of habitats. One controversial issue is whether upstream males are excluded from lower elevations by resident bats. We tested this by translocating 10 upstream males to a downstream roost: eight returned to the high elevation site in 1-2 nights, two persisted at low altitude but did not roost with resident bats. These results are consistent with the idea of segregation due to competition. Living at high altitude allows for more effective heterothermy and may thus be not detrimental for survival, but by staying at lower altitude males increase proximity to females and potentially benefit from summer mating opportunities. PMID:26230548

Influences of Mating Group Composition on the Behavioral Time-Budget of Male and Female Alpine Ibex (Capra ibex) during the Rut

PubMed Central

Tettamanti, Federico; Viblanc, Vincent A.

2014-01-01

During the rut, polygynous ungulates gather in mixed groups of individuals of different sex and age. Group social composition, which may vary on a daily basis, is likely to have strong influences on individual’s time-budget, with emerging properties at the group-level. To date, few studies have considered the influence of group composition on male and female behavioral time budget in mating groups. Focusing on a wild population of Alpine ibex, we investigated the influence of group composition (adult sex ratio, the proportion of dominant to subordinate males, and group size) on three behavioral axes obtained by Principal Components Analysis, describing male and female group time-budget. For both sexes, the first behavioral axis discerned a trade-off between grazing and standing/vigilance behavior. In females, group vigilance behavior increased with increasingly male-biased sex ratio, whereas in males, the effect of adult sex ratio on standing/vigilance behavior depended on the relative proportion of dominant males in the mating group. The second axis characterized courtship and male-male agonistic behavior in males, and moving and male-directed agonistic behavior in females. Mating group composition did not substantially influence this axis in males. However, moving and male-directed agonistic behavior increased at highly biased sex ratios (quadratic effect) in females. Finally, the third axis highlighted a trade-off between moving and lying behavior in males, and distinguished moving and female-female agonistic behavior from lying behavior in females. For males, those behaviors were influenced by a complex interaction between group size and adult sex ratio, whereas in females, moving and female-female agonistic behaviors increased in a quadratic fashion at highly biased sex ratios, and also increased with increasing group size. Our results reveal complex behavioral trade-offs depending on group composition in the Alpine ibex, and emphasize the importance of social factors in influencing behavioral time-budgets of wild ungulates during the rut. PMID:24416453

Complementary transcriptome and proteome profiling in cabbage buds of a recessive male sterile mutant provides new insights into male reproductive development.

PubMed

Ji, Jialei; Yang, Limei; Fang, Zhiyuan; Zhuang, Mu; Zhang, Yangyong; Lv, Honghao; Liu, Yumei; Li, Zhansheng

2018-05-15

Plant male reproductive development is a very complex biological process that involves multiple metabolic pathways. To reveal novel insights into male reproductive development, we conducted an integrated profiling of gene activity in the developing buds of a cabbage recessive genetic male sterile mutant. Using RNA-Seq and label-free quantitative proteomics, 2881 transcripts and 1245 protein species were identified with significant differential abundance between the male sterile line 83121A and its isogenic maintainer line 83121B. Analyses of function annotations and correlations between transcriptome and proteome and protein interaction networks were also conducted, which suggested that the male sterility involves a complex regulatory pattern. Moreover, several key biological processes, such as fatty acid metabolism, tapetosome biosynthesis, amino acid metabolism and protein synthesis and degradation were identified as being of relevance to male reproductive development. A large number of protein species involved in sporopollenin synthesis, amino acid synthesis, ribosome assembly, protein processing in endoplasmic reticulum and lipid transfer were observed to be significantly down-accumulated in 83121A buds, indicating their potential roles in the regulation of cabbage microspore abortion. In summary, the conjoint analysis of the transcriptome and proteome provided a global picture regarding the molecular dynamics in male sterile buds of 83121A. Male sterile mutants are excellent materials for the study of plant male reproductive development. This study revealed the molecular dynamics of recessive male sterility in cabbage at the transcriptome and proteome levels, which deepens our understanding of the metabolic pathways involved in male development. Moreover, the male sterility-related genes identified in this study could provide a reference for the artificial regulation of cabbage fertility by using genetic engineering technology, which may result in potential applications in agriculture such as production of hybrid seeds using male sterility. Copyright © 2018 Elsevier B.V. All rights reserved.

Colour Cues That Are Not Directly Attached to the Body of Males Do Not Influence the Mate Choice of Zebra Finches.

PubMed

Krause, E Tobias

2016-01-01

Mate choice decisions of female zebra finches are generally thought to rely on the assessment of male quality, which includes the specific ornamentation of males. A commonly used paradigm to experimentally manipulate a male's attractiveness is to add a coloured leg ring to the bird. Some studies have shown that female zebra finches prefer or alter their investment in males that have an additional red leg ring compared with males with green leg rings. Whether the coloured artificial ornaments need to be attached to the male's body or whether environmental colouration could have a similar effect on male attractiveness remains unclear. Here, I investigated this novel context to determine whether female choice between males is affected by environmental colour cues that are not directly attached to the male's body in four experiments involving 220 zebra finches (Taeniopygia guttata). A first experiment revealed that females chose males with red colour cues in the environmental background over males with green cues in the background. Based on this finding, I conducted follow-up experiments to obtain a deeper understanding of how environmental colour cues affect mate choice. Therefore, I examined whether female choice behaviour or male behaviour was altered in two additional experiments. Both experiments failed to show any effects of environmental colour cues on female choice or on male behaviour. Therefore, I replicated the initial experiment in a fourth experiment. Again replication failed; thus, the initial results indicating that environmental colouration affects mate choice behaviour of female zebra finches were not supported by the three subsequent experiments; thus, the outcome of the first experiment seems to be a false positive. Taking my results together, I found no robust support for the idea that environmental colour cues that are not directly attached to the body of male zebra finches affect female mate choice decisions.

Sugar administration to newly emerged Aedes albopictus males increases their survival probability and mating performance.

PubMed

Bellini, Romeo; Puggioli, Arianna; Balestrino, Fabrizio; Brunelli, Paolo; Medici, Anna; Urbanelli, Sandra; Carrieri, Marco

2014-04-01

Aedes albopictus male survival in laboratory cages is no more than 4-5 days when kept without any access to sugar indicating their need to feed on a sugar source soon after emergence. We therefore developed a device to administer energetic substances to newly emerged males when released as pupae as part of a sterile insect technique (SIT) programme, made with a polyurethane sponge 4 cm thick and perforated with holes 2 cm in diameter. The sponge was imbibed with the required sugar solution and due to its high retention capacity the sugar solution was available for males to feed for at least 48 h. When evaluated in lab cages, comparing adults emerged from the device with sugar solution vs the device with water only (as negative control), about half of the males tested positive for fructose using the Van Handel anthrone test, compared to none of males in the control cage. We then tested the tool in semi-field and in field conditions with different sugar concentrations (10%, 15%, and 20%) and compared results to the controls fed with water only. Males were recaptured by a battery operated manual aspirator at 24 and 48 h after pupae release. Rather high share 10-25% of captured males tested positive for fructose in recollections in the vicinity of the control stations, while in the vicinity of the sugar stations around 40-55% of males were positive, though variability between replicates was large. The sugar positive males in the control test may have been released males that had access to natural sugar sources found close to the release station and/or wild males present in the environment. Only a slight increase in the proportion of positive males was obtained by increasing the sugar concentration in the feeding device from 10% to 20%. Surprisingly, modification of the device to add a black plastic inverted funnel above the container reduced rather than increased the proportion of fructose positive males collected around the station. No evidence of difference in the capacity of sterile (irradiated with 30 Gy) males to take a sugar meal relative to fertile males was observed in field comparison. A clear effect of temperature and relative humidity (RH) on the rate of sugar positive males was observed, with an increase of temperature and a decrease in RH strongly increasing the % of sugar positive males. In large enclosures we tested the effect of our sugar supplying tool on the mating competitiveness of sterile vs fertile males, which produced an evident favorable effect both on sterile and fertile males. Copyright © 2013 International Atomic Energy Agency 2013. Published by Elsevier B.V. All rights reserved.

Behavioural and physiological consequences of male reproductive trade-offs in edible dormice ( Glis glis)

NASA Astrophysics Data System (ADS)

Fietz, Joanna; Klose, Stefan M.; Kalko, Elisabeth K. V.

2010-10-01

Testosterone mediates male reproductive trade-offs in vertebrates including mammals. In male edible dormice ( Glis glis), reproductivity linked to high levels of testosterone reduces their ability to express torpor, which may be expected to dramatically increase thermoregulatory costs. Aims of this study were therefore to analyse behavioural and physiological consequences of reproductive activity in male edible dormice under ecologically and evolutionary relevant conditions in the field. As we frequently encountered sleeping groups in the field, we hypothesized that social thermoregulation should be an important measure to reduce energy expenditure especially in sexually active male edible dormice. Our results revealed that the occurrence of sleeping groups was negatively influenced by male body mass but not by reproductive status or ambient temperature. In reproductive as in non-reproductive males, the number of individuals huddling together was negatively influenced by their body mass. Thus in general males with a high body mass were sitting in smaller groups than males with a low body mass. However, in reproductive males group size was further negatively affected by ambient temperature and positively by testes size. Thus breeders formed larger sleeping groups at lower ambient temperatures and males with larger testes were found in larger groups than males with smaller testes. Measurements of oxygen consumption demonstrated that grouping behaviour represents an efficient strategy to reduce energy expenditure in edible dormice as it reduced energy requirements by almost 40%. In summary, results of this field study showcase how sexually active male edible dormice may, through behavioural adjustment, counterbalance high thermoregulatory costs associated with reproductive activity.

Incidence of Male-Killing Rickettsia spp. (α-Proteobacteria) in the Ten-Spot Ladybird Beetle Adalia decempunctata L. (Coleoptera: Coccinellidae)

PubMed Central

von der Schulenburg, J. Hinrich Graf; Habig, Michael; Sloggett, John J.; Webberley, K. Mary; Bertrand, Dominique; Hurst, Gregory D. D.; Majerus, Michael E. N.

2001-01-01

The diversity of endosymbiotic bacteria that kill male host offspring during embryogenesis and their frequencies in certain groups of host taxa suggest that the evolution of male killing and the subsequent spread of male-killing symbionts are primarily determined by host life history characteristics. We studied the 10-spot ladybird beetle, Adalia decempunctata L. (Coleoptera: Coccinellidae), in which male killing has not been recorded previously, to test this hypothesis, and we also assessed the evolution of the male killer identified by DNA sequence analysis. Our results show that A. decempunctata harbors male-killing Rickettsia (α-proteobacteria). Male-killing bacteria belonging to the genus Rickettsia have previously been reported only for the congeneric two-spot ladybird beetle, Adalia bipunctata L. Phylogenetic analysis of Rickettsia DNA sequences isolated from different populations of the two host species revealed a single origin of male killing in the genus Rickettsia. The data also indicated possible horizontal transfer of symbionts between host species. In addition, A. bipunctata is known to bear at least four different male-killing symbionts in its geographic range two of which coexist in the two locations from which A. decempunctata specimens were obtained for the present study. Since only a single male-killing taxon was found in A. decempunctata, we assume that the two closely related ladybird beetle species must differ in the number and/or geographic distribution of male killers. We discuss the importance of these findings to our understanding of the evolution and dynamics of symbiotic associations between male-killing bacteria and their insect hosts. PMID:11133455

Are mechanics different between male and female runners with patellofemoral pain?

PubMed Central

Willy, Richard W.; Manal, Kurt T.; Witvrouw, Erik E.; Davis, Irene S.

2012-01-01

Introduction Patellofemoral pain (PFP) has often been attributed to abnormal hip and knee mechanics in females. To date, there have been few investigations of the hip and knee mechanics of males with PFP. The purpose of this study was to compare the lower extremity mechanics and alignment of male runners with PFP with healthy male runners and female runners with PFP. We hypothesized that males with PFP would move with greater varus knee mechanics compared with male controls and compared with females with PFP. Further, it was hypothesized that males with PFP would demonstrate greater varus alignment. Methods A gait and single leg squat analysis was conducted on each group (18 runners per group). Measurement of each runner’s tibial mechanical axis was also recorded. Motion data were processed using Visual 3D (CMotion, Bethesda, Md., USA). Analyses of Variance were used to analyze the data. Results Males with PFP ran and squatted in greater peak knee adduction and demonstrated greater peak knee external adduction moment compared with healthy male controls. In addition, males with PFP ran and squatted with less peak hip adduction and greater peak knee adduction compared with females with PFP. The static measure of mechanical axis of the tibial was not different between groups. However, a post-hoc analysis revealed that males with PFP ran with greater peak tibial segmental adduction. Conclusion Males with PFP demonstrated different mechanics during running and during a single leg squat compared with females with PFP and with healthy males. Based upon the results of this study, therapies for PFP may need to be sex-specific. PMID:22843103

Selection on male size, leg length and condition during mate search in a sexually highly dimorphic orb-weaving spider.

PubMed

Foellmer, Matthias W; Fairbairn, Daphne J

2005-02-01

Mate search plays a central role in hypotheses for the adaptive significance of extreme female-biased sexual size dimorphism (SSD) in animals. Spiders (Araneae) are the only free-living terrestrial taxon where extreme SSD is common. The "gravity hypothesis" states that small body size in males is favoured during mate search in species where males have to climb to reach females, because body length is inversely proportional to achievable speed on vertical structures. However, locomotive performance of males may also depend on relative leg length. Here we examine selection on male body size and leg length during mate search in the highly dimorphic orb-weaving spider Argiope aurantia, using a multivariate approach to distinguish selection targeted at different components of size. Further, we investigate the scaling relationships between male size and energy reserves, and the differential loss of reserves. Adult males do not feed while roving, and a size-dependent differential energy storage capacity may thus affect male performance during mate search. Contrary to predictions, large body size was favoured in one of two populations, and this was due to selection for longer legs. Male size was not under selection in the second population, but we detected direct selection for longer third legs. Males lost energy reserves during mate search, but this was independent of male size and storage capacity scaled isometrically with size. Thus, mate search is unlikely to lead to selection for small male size, but the hypothesis that relatively longer legs in male spiders reflect a search-adapted morphology is supported.

Effects of RNAi-Mediated Knockdown of Histone Methyltransferases on the Sex-Specific mRNA Expression of Imp in the Silkworm Bombyx mori

PubMed Central

Suzuki, Masataka G.; Ito, Haruka; Aoki, Fugaku

2014-01-01

Sexual differentiation in Bombyx mori is controlled by sex-specific splicing of Bmdsx, which results in the omission of exons 3 and 4 in a male-specific manner. In B. mori, insulin-like growth factor II mRNA-binding protein (Imp) is a male-specific factor involved in male-specific splicing of Bmdsx. Male-specific Imp mRNA results from the male-specific inclusion of exon 8. To verify the link between histone methylation and alternative RNA processing in Imp, we examined the effects of RNAi-mediated knockdown of several histone methyltransferases on the sex-specific mRNA expression of Imp. As a result, male-specific expression of Imp mRNA was completely abolished when expression of the H3K79 methyltransferase DOT1L was repressed to <10% of that in control males. Chromatin immunoprecipitation-quantitative PCR analysis revealed a higher distribution of H3K79me2 in normal males than in normal females across Imp. RNA polymerase II (RNAP II) processivity assays indicated that RNAi knockdown of DOT1L in males caused a twofold decrease in RNAP II processivity compared to that in control males, with almost equivalent levels to those observed in normal females. Inhibition of RNAP II-mediated elongation in male cells repressed the male-specific splicing of Imp. Our data suggest the possibility that H3K79me2 accumulation along Imp is associated with the male-specific alternative processing of Imp mRNA that results from increased RNAP II processivity. PMID:24758924

Experience modulates the influence of gonadal hormones on sexual orientation of male rats.

PubMed

Matuszczyk, J V; Larsson, K

1994-03-01

The aim of this study was to investigate whether heterosexual experience influences the male's partner preference and the role of gonadal hormones, including several androgens and estradiol, on female-oriented behavior. In the first experiment, the animals were exposed to a four-stimuli test situation including a sexually active male, a castrated male, an estrous female, and an ovariectomized (ovx) female. Castrated naive and experienced male rats were implanted with either testosterone (T), estradiol (E2), or an empty tubing (blank) and compared to intact naive and experienced male rats. None of the naive animals, whether castrated or intact, showed a consistent preference for any of the four stimuli. Whereas when sexually experienced, only intact and T-treated males showed a female-oriented preference. In the second experiment, the animals were allowed to choose between an active male and an estrous female. Castrated naive male rats were implanted with either T, E2, or DHT, or injected daily SC with the synthetic nonaromatizable androgen, methyltrienelone (R 1881). Two groups of intact males, one consisting of experienced and the other of naive animals, were also included in this experiment. The experienced intact males showed a significant preference for the estrous female, while the intact naive males showed no preference for either of the two stimuli. After the animals had gained heterosexual experience, intact and androgen-treated males showed a significant preference for the female. Neither the administration of R 1881 nor E2 promoted a female-oriented behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of a knee brace intervention on perceived pain and patellofemoral loading in recreational athletes.

PubMed

Sinclair, Jonathan K; Selfe, James; Taylor, Paul J; Shore, Hannah F; Richards, Jim D

2016-08-01

The current investigation aimed to investigate the effects of an intervention using knee bracing on pain symptoms and patellofemoral loading in male and female recreational athletes. Twenty participants (11 males & 9 females) with patellofemoral pain were provided with a knee brace which they wore for a period of 2weeks. Lower extremity kinematics and patellofemoral loading were obtained during three sport specific tasks, jog, cut and single leg hop. In addition their self-reported knee pain scores were examined using the Knee injury and Osteoarthritis Outcome Score. Data were collected before and after wearing the knee brace for 2weeks. Significant reductions were found in the run and cut movements for peak patellofemoral force/pressure and in all movements for the peak knee abduction moment when wearing the brace. Significant improvements were also shown for Knee injury and Osteoarthritis Outcome Score subscale symptoms (pre: male=70.27, female=73.22 & post: male=85.64, female=82.44), pain (pre: male=72.36, female=78.89 & post: male=85.73, female=84.20), sport (pre: male=60.18, female=59.33 & post: male=80.91, female=79.11), function and daily living (pre: male=82.18, female=86.00 & post: male=88.91, female=90.00) and quality of life (pre: male=51.27, female=54.89 & post: male=69.36, female=66.89). Male and female recreational athletes who suffer from patellofemoral pain can be advised to utilise knee bracing as a conservative method to reduce pain symptoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Colour bands, mate choice and paternity in the bluethroat.

PubMed

Johnsen; Fiske; Amundsen; Lifjeld; Rohde

2000-01-01

Studies of several bird species have shown that coloured leg bands may affect a male's success in mate attraction and/or mating competition. From a colour band experiment in the field, we have previously reported that male bluethroats, Luscinia s. svecica, with blue and orange bands (BO males) guarded their mates less intensely at the peak of female fertility, and spent more time advertising for additional mates, than males banded with non-BO colours. These responses indicated that BO males experienced less threat to their paternity than did non-BO males, possibly mediated through an increased attractiveness. Here we present paternity analyses of the broods from the field study and test whether there were differences between the two male groups in within-pair or extrapair paternity. There were no significant differences between the two groups of males in paternity, suggesting effective male protection of paternity. However, extrapair paternity was infrequent in the 2 years of the field experiment; hence, the power in detecting effects on paternity does not allow a definitive conclusion on this issue. We also conducted an aviary experiment in which females were given the choice between a BO male and a non-BO male, to test whether females had preferences for particular colour bands. Females did not associate more with BO males, as would have been expected if these males were more attractive in social mate choice. Our results suggest that the effects of colour bands on social mate choice and paternity are, at best, weak. Copyright 2000 The Association for the Study of Animal Behaviour.

Heterosis Increases Fertility, Fecundity, and Survival of Laboratory-Produced F1 Hybrid Males of the Malaria Mosquito Anopheles coluzzii

PubMed Central

Ekechukwu, Nkiru E.; Baeshen, Rowida; Traorè, Sékou F.; Coulibaly, Mamadou; Diabate, Abdoulaye; Catteruccia, Flaminia; Tripet, Frédéric

2015-01-01

The success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically-modified male mosquitoes critically depends on mating between laboratory-reared males and wild females. Unfortunately, mosquito colonization, laboratory rearing, and genetic manipulations can all negatively affect male competitiveness. Heterosis is commonly used to produce domestic animals with enhanced vigor and homogenous genetic background and could therefore potentially improve the mating performance of mass-reared male mosquitoes. Here, we produced enhanced hybrid males of the malaria mosquito Anopheles coluzzii by crossing two strains colonized >35 and 8 years ago. We compared the amount of sperm and mating plug proteins they transferred to females, as well as their insemination rate, reproductive success and longevity under various experimental conditions. Across experiments, widespread adaptations to laboratory mating were detected in the older strain. In large-group mating experiments, no overall hybrid advantage in insemination rates and the amount of sperm and accessory gland proteins transferred to females was detected. Despite higher sperm activity, hybrid males did not appear more fecund. However, individual-male mating and laboratory-swarm experiments revealed that hybrid males, while inseminating fewer females than older inbred males, were significantly more fertile, producing larger mating plugs and drastically increasing female fecundity. Heterotic males also showed increased longevity. These results validate the use of heterosis for creating hybrid males with improved fitness from long-established inbred laboratory strains. Therefore, this simple approach could facilitate disease control strategies based on male mosquito releases with important ultimate benefits to human health. PMID:26497140

Male discrimination of receptive and unreceptive female calls by temporal features

PubMed Central

Elliott, Taffeta M.; Kelley, Darcy B.

2012-01-01

Summary In murky, crowded ponds in South Africa, female clawed frogs, Xenopus laevis (Daudin), vocalize to signal reproductive state. Female calls consist of acoustically similar clicks delivered in trains with characteristic rates. The rapping call of a sexually receptive female has a more rapid click rate [81 ms mean interclick interval (ICI)] than the ticking call of an unreceptive female (219 ms ICI). Rapping stimulates male advertisement calling, whereas ticking suppresses an already calling male. We examined how males label and discriminate female click rates. A labeling boundary experiment revealed that males perceive click rates between the means of rapping and ticking as lying on a continuum. They respond to 98 and 160 ms ICI as though to rapping and ticking, respectively. However, calling evoked by a click rate equally common to both calls (120 ms ICI) did not differ from the response to either rapping or ticking. A second experiment evaluated whether males discriminate click rates both labeled as ticking (180 and 219 ms ICI). Ticking suppresses advertising males, and suppressed males habituate (resume calling) to prolonged ticking. Both ticking stimuli suppressed males with equal effectiveness, and males habituated in equivalent amounts of time. When the stimulus was switched during habituation, no dishabituation occurred. We conclude that male labeling of click trains as rapping or ticking reflects an ambiguity resulting from the overlap in ICIs naturally occurring in the calls. Males do not respond differentially to click rates within the ticking category. Males thus combine discriminating and non-discriminating strategies in responding to the salient feature of female calls. PMID:17690231

Sexual selection in a lekking bird: the relative opportunity for selection by female choice and male competition.

PubMed

DuVal, Emily H; Kempenaers, Bart

2008-09-07

Leks are classic models for studies of sexual selection due to extreme variance in male reproductive success, but the relative influence of intrasexual competition and female mate choice in creating this skew is debatable. In the lekking lance-tailed manakin (Chiroxiphia lanceolata), these selective episodes are temporally separated into intrasexual competition for alpha status and female mate choice among alpha males that rarely interact. Variance in reproductive success between status classes of adult males (alpha versus non-alpha) can therefore be attributed to male-male competition whereas that within status largely reflects female mate choice. This provides an excellent opportunity for quantifying the relative contribution of each of these mechanisms of sexual selection to the overall opportunity for sexual selection on males (I males). To calculate variance in actual reproductive success, we assigned genetic paternity to 92.3% of 447 chicks sampled in seven years. Reproduction by non-alphas was rare and apparently reflected status misclassifications or opportunistic copulations en route to attaining alpha status rather than alternative mating strategies. On average 31% (range 7-44%, n=6 years) of the total I males was due to variance in reproductive success between alphas and non-alphas. Similarly, in a cohort of same-aged males followed for six years, 44-58% of the total I males was attributed to variance between males of different status. Thus, both intrasexual competition for status and female mate choice among lekking alpha males contribute substantially to the potential for sexual selection in this species.

Mating competitiveness of male Anopheles arabiensis mosquitoes irradiated with a partially or fully sterilizing dose in small and large laboratory cages.

PubMed

Helinski, M E H; Knols, B G J

2008-07-01

Male mating competitiveness is a crucial parameter in many genetic control programs including the sterile insect technique (SIT). We evaluated competitiveness of male Anopheles arabiensis Patton as a function of three experimental variables: (1) small or large cages for mating, (2) the effects of either a partially sterilizing (70 Gy) or fully sterilizing (120 Gy) dose, and (3) pupal or adult irradiation. Irradiated males competed for females with an equal number of unirradiated males. Competitiveness was determined by measuring hatch rates of individually laid egg batches. In small cages, pupal irradiation with the high dose resulted in the lowest competitiveness, whereas adult irradiation with the low dose gave the highest, with the latter males being equal in competitiveness to unirradiated males. In the large cage, reduced competitiveness of males irradiated in the pupal stage was more pronounced compared with the small cage; the males irradiated as adults at both doses performed similarly to unirradiated males. Unexpectedly, males irradiated with the high dose performed better in a large cage than in a small one. A high proportion of intermediate hatch rates was observed for eggs collected in the large cage experiments with males irradiated at the pupal stage. It is concluded that irradiation of adult An. arabiensis with the partially sterilizing dose results in the highest competitiveness for both cage designs. Cage size affected competitiveness for some treatments; therefore, competitiveness determined in laboratory experiments must be confirmed by releases into simulated field conditions. The protocols described are readily transferable to evaluate male competitiveness for other genetic control techniques.

Sperm competition games between sneaks and guards: a comparative analysis using dimorphic male beetles.

PubMed

Simmons, Leigh W; Emlen, Douglas J; Tomkins, Joseph L

2007-11-01

Sperm competition is widely recognized as a pervasive force of sexual selection. Theory predicts that across species increased risk of sperm competition should favor an increased expenditure on the ejaculate, a prediction for which there is much evidence. Sperm competition games have also been developed specifically for systems in which males adopt the alternative male mating tactics of sneaking copulations or guarding females. These models have not yet been tested in a comparative context, but predict that: across species male expenditure on the ejaculate should increase with increasing probability of a sneak mating; within species, sneaks should have the greater expenditure on the ejaculate; and the disparity in expenditure between sneaks and guards should be greatest in species with moderate risk of a sneak mating, and decline toward parity in species with low or high risk. Beetles in the genus Onthophagus are often characterized by dimorphic male morphologies that reflect the alternative mating tactics of sneak (minor males) and guard (major males). We conducted a comparative analysis across 16 species of male dimorphic onthophagines, finding that testes size increased across species with increasing frequency of the minor male phenotype. Minor males generally had the greater testes size, but across species the disparity between morphs was independent of the frequency of minor males. We present data on testes allometry from two populations of O. taurus that have undergone genetic divergence in the frequency of minor males. Consistent with the comparative analysis, these data support the notion that the relative frequency of sneaks in the population influences male expenditure on the ejaculate.

Inbreeding avoidance and female mate choice shape reproductive skew in capuchin monkeys (Cebus capucinus imitator).

PubMed

Wikberg, Eva C; Jack, Katharine M; Fedigan, Linda M; Campos, Fernando A; Yashima, Akiko S; Bergstrom, Mackenzie L; Hiwatashi, Tomohide; Kawamura, Shoji

2017-01-01

Reproductive skew in multimale groups may be determined by the need for alpha males to offer reproductive opportunities as staying incentives to subordinate males (concessions), by the relative fighting ability of the alpha male (tug-of-war) or by how easily females can be monopolized (priority-of-access). These models have rarely been investigated in species with exceptionally long male tenures, such as white-faced capuchins, where female mate choice for novel unrelated males may be important in shaping reproductive skew. We investigated reproductive skew in white-faced capuchins at Sector Santa Rosa, Costa Rica, using 20 years of demographic, behavioural and genetic data. Infant survival and alpha male reproductive success were highest in small multimale groups, which suggests that the presence of subordinate males can be beneficial to the alpha male, in line with the concession model's assumptions. None of the skew models predicted the observed degree of reproductive sharing, and the probability of an alpha male producing offspring was not affected by his relatedness to subordinate males, whether he resided with older subordinate males, whether he was prime aged, the number of males or females in the group or the number of infants conceived within the same month. Instead, the alpha male's probability of producing offspring decreased when he was the sire of the mother, was weak and lacked a well-established position and had a longer tenure. Because our data best supported the inbreeding avoidance hypothesis and female choice for strong novel mates, these hypotheses should be taken into account in future skew models. © 2016 John Wiley & Sons Ltd.

The influence of gender on the communication skills assessment of medical students.

PubMed

Huang, Chin-Chou; Huang, Chia-Chang; Yang, Ying-Ying; Lin, Shing-Jong; Chen, Jaw-Wen

2015-11-01

Opinions on the interaction between the genders of standardized patients and examinees are controversial. Our study sought to determine the influence of gender on communication skills assessment in Eastern country. We recruited year 5 medical students from a medical college in Taiwan. They were assigned to obtain informed consent from either male or female age-matched standardized patients. Their performance was rated by standardized checklist rating scores and global rating scores. Either male or female examiners rated their performance. A total of 253 medical students (166 male students and 87 female students) were recruited. The checklist rating scores for students interacting with male standardized patients were significantly lower than the scores for interactions with female standardized patients (male examiners, P=0.006; female examiners, P=0.001). For male students, the checklist rating scores were significantly lower for male standardized patients than for female standardized patients (male examiners, P=0.006; female examiners, P=0.008). For male standardized patients, male students had significantly lower checklist rating scores than female students when rated by male examiners (P=0.044). The global rating scores were similar except when female students interacted with male and female SPs and when rated by female examiners (P=0.004). The gender of standardized patients influences communication skills assessment. In terms of checklist rating scores, female standardized patients seem preferable to minimize potential gender effects. In the best interest of students, global rating score may be preferable to checklist rating score, especially for male examinees. Copyright © 2015 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Effects of playing a violent video game as male versus female avatar on subsequent aggression in male and female players.

PubMed

Yang, Grace S; Huesmann, L Rowell; Bushman, Brad J

2014-01-01

Previous research has shown that violent video games can increase aggression in players immediately after they play. The present research examines the effects of one subtle cue within violent video games that might moderate these effects-whether the avatar is male or female. One common stereotype is that males are more aggressive than females. Thus, playing a violent video game as a male avatar, compared to a female avatar, should be more likely to prime aggressive thoughts and inclinations in players and lead to more aggressive behavior afterwards. Male and female university students (N = 242) were randomly assigned to play a violent video game as a male or female avatar. After gameplay, participants gave an ostensible partner who hated spicy food hot sauce to eat. The amount of hot sauce given was used to measure aggression. Consistent with priming theory, results showed that both male and female participants who played a violent game as a male avatar behaved more aggressively afterwards than those who played as female avatar. The priming effects of the male avatar were somewhat stronger for male participants than for female participants, suggesting that male participants identified more with the male avatar than did the female participants. These results are particularly noteworthy because they are consistent with another recent experiment showing that playing a violent game as an avatar with a different stereotypically aggressive attribute (black skin color) stimulates more aggression than playing as an avatar without the stereotypically aggressive attribute (Yang et al., 2014, Social Psychological and Personality Science). © 2014 Wiley Periodicals, Inc.

Androgen responses to reproductive competition of males pursuing either fixed or plastic alternative reproductive tactics.

PubMed

von Kuerthy, Corinna; Ros, Albert F H; Taborsky, Michael

2016-11-15

Alternative reproductive tactics (ARTs), which can be plastic or fixed for life, may be characterized by distinct hormonal profiles. The relative plasticity hypothesis predicts flexible androgen regulation for adult males pursuing plastic tactics, but a less flexible regulation for males using a fixed tactic throughout life. Furthermore, androgen profiles may respond to changes in the social environment, as predicted by the social reciprocity models of hormone/behaviour interactions. The cichlid fish Lamprologus callipterus provides a rare opportunity to study the roles of androgens for male ARTs within a single species, because fixed and plastic ARTs coexist. We experimentally exposed males to competitors pursuing either the same or different tactics to test predictions of the relative plasticity and the social reciprocity models. Androgen profiles of different male types partly comply with predictions derived from the relative plasticity hypothesis: males of the plastic bourgeois/sneaker male trajectory showed different 11-ketotestosterone (11-KT) levels when pursuing either bourgeois or parasitic sneaker male behaviours. Surprisingly, males pursuing the fixed dwarf male tactic showed the highest free and conjugated 11-KT and testosterone (T) levels. Our experimental social challenges significantly affected the free 11-KT levels of bourgeois males, but the androgen responses did not differ between challenges involving different types of competitors. Furthermore, the free T-responses of the bourgeois males correlated with their aggressive behaviour exhibited against competitors. Our results provide new insights into the endocrine responsiveness of fixed and plastic ARTs, confirming and refuting some predictions of both the relative plasticity and the social reciprocity models. © 2016. Published by The Company of Biologists Ltd.

Six new species of the spider family Ochyroceratidae Fage 1912 (Arachnida: Araneae) from Southeast Asia.

PubMed

Li, Fengyuan; Li, Shuqiang; Jäger, Peter

2014-02-25

Five new Althepus species and one new Psiloderces species of the family Ochyroceratidae are described from Southeast Asia: Althepus erectus spec. nov. (male) and A. nophaseudi spec. nov. (male, female) from Laos, A. flabellaris spec. nov. (male, female) from Thailand, A. reduncus spec. nov. (male) from Myanmar, A. spiralis spec. nov. (male) from Malaysia, and Psiloderces dicellocerus spec. nov. (male) from Indonesia. Primary types are deposited in the Senckenberg Research Institute in Frankfurt, Germany (SMF).

Design, Tuning and Performance Evaluation of an Automated Pulmonary Nodule Detection System.

DTIC Science & Technology

1983-02-01

comprised of younger males. Lung cancer has been shown to be about four (lines more prevalent in males (21% of all males cancers ) than in females (5% of...all female cancers ) IAMN. 1973]. The prevalence of the solitary pulmonary nodule (SPN) has been reported betweem I pet 100 (films studied) (Holin...younger males. Lung cance: has been shown to bc about four times noll prevalent in males (21% of all males cancers ) than in females (5% of all female

Insurance coverage for male infertility care in the United States.

PubMed

Dupree, James M

2016-01-01

Infertility is a common condition experienced by many men and women, and treatments are expensive. The World Health Organization and American Society of Reproductive Medicine define infertility as a disease, yet private companies infrequently offer insurance coverage for infertility treatments. This is despite the clear role that healthcare insurance plays in ensuring access to care and minimizing the financial burden of expensive services. In this review, we assess the current knowledge of how male infertility care is covered by insurance in the United States. We begin with an appraisal of the costs of male infertility care, then examine the state insurance laws relevant to male infertility, and close with a discussion of why insurance coverage for male infertility is important to both men and women. Importantly, we found that despite infertility being classified as a disease and males contributing to almost half of all infertility cases, coverage for male infertility is often excluded from health insurance laws. Excluding coverage for male infertility places an undue burden on their female partners. In addition, excluding care for male infertility risks missing opportunities to diagnose important health conditions and identify reversible or irreversible causes of male infertility. Policymakers should consider providing equal coverage for male and female infertility care in future health insurance laws.

Male and female contributions to behavioral isolation in darters as a function of genetic distance and color distance

PubMed Central

Moran, Rachel L.; Zhou, Muchu; Catchen, Julian M.; Fuller, Rebecca C.

2017-01-01

Abstract Determining which reproductive isolating barriers arise first between geographically isolated lineages is critical to understanding allopatric speciation. We examined behavioral isolation among four recently diverged allopatric species in the orangethroat darter clade (Etheostoma: Ceasia). We also examined behavioral isolation between each Ceasia species and the sympatric rainbow darter Etheostoma caeruleum. We asked (1) is behavioral isolation present between allopatric Ceasia species, and how does this compare to behavioral isolation with E. caeruleum, (2) does male color distance and/or genetic distance predict behavioral isolation between species, and (3) what are the relative contributions of female choice, male choice, and male competition to behavioral isolation? We found that behavioral isolation, genetic differentiation, and male color pattern differentiation were present between allopatric Ceasia species. Males, but not females, discerned between conspecific and heterospecific mates. Males also directed more aggression toward conspecific rival males. The high levels of behavioral isolation among Ceasia species showed no obvious pattern with genetic distance or male color distance. However, when the E. caeruleum was included in the analysis, an association between male aggression and male color distance was apparent. We discuss the possibility that reinforcement between Ceasia and E. caeruleum is driving behavioral isolation among allopatric Ceasia species. PMID:28776645

Reversed sex change by widowed males in polygynous and protogynous fishes: female removal experiments in the field.

PubMed

Kuwamura, Tetsuo; Suzuki, Shohei; Kadota, Tatsuru

2011-12-01

Sex change, either protogyny (female to male) or protandry (male to female), is well known among fishes, but evidence of bidirectional sex change or reversed sex change in natural populations is still very limited. This is the first report on female removal experiments for polygnous and protogynous fish species to induce reversed sex change in the widowed males in the field. We removed all of the females and juveniles from the territories of dominant males in the cleaner wrasse Labroides dimidiatus (Labridae) and the rusty angelfish Centropyge ferrugata (Pomacanthidae) on the coral reefs of Okinawa. In both species, if new females or juveniles did not immigrate into the territories of the widowed males, some of them emigrated to form male-male pairs. When a male-male pair formed, the smaller, subordinate partner began to perform female sexual behaviours (n = 4 in L. dimidiatus; n = 2 in C. ferrugata) and, finally, released eggs (n = 1, respectively). Thus, the reversed sex change occurred in the widowed males according to the change of their social status. These results suggest that such female removal experiments will contribute to the discovery of reversed sex change in the field also in other polygnous and protogynous species.

Parental care compromises feeding in the pumpkinseed ( Lepomis gibbosus)

NASA Astrophysics Data System (ADS)

Zięba, G.; Dukowska, M.; Przybylski, M.; Fox, M. G.; Smith, C.

2018-04-01

Providing parental care is potentially costly. Costs can arise through elevated energy expenditure or from an increased risk of mortality. A cost of parental care can also occur because a parent is compromised in their ability to forage. We used pumpkinseed Lepomis gibbosus, a fish with an alternative male mating strategy, to test whether parental males differed in their feeding in comparison with females and cuckolder males. To address this question, we examined the stomach contents of female, cuckolder male, and parental male pumpkinseed during the breeding season over an entire diel cycle. We showed that parental males had a lower total weight of food in their stomachs in comparison with females, while cuckolder males did not. Parental males also had a lower weight and number of chironomids in their stomachs. The temporal pattern of feeding of parental males diverged from that of females, and they had a lower probability of pupal chironomids in their stomachs, which implies spatial segregation in foraging. Parental males had a greater probability of conspecific eggs in their stomachs than females, while the probability of egg cannibalism did not differ between cuckolder males and females. Overall, these finding meet predictions in accordance with an assumption that parental care and territoriality can compromise feeding.

Male-Male Mounting Behaviour in Free-Ranging Golden Snub-Nosed Monkeys (Rhinopithecus roxellana).

PubMed

Fang, Gu; Dixson, Alan F; Qi, Xiao-Guang; Li, Bao-Guo

2018-01-01

An all-male band of golden snub-nosed monkeys (Rhinopithecus roxellana) was observed for 3 months in the Qinling Mountains of China, in order to collect data on the frequencies and contextual significance of male-male mounting behaviour. Mounts occurred in a variety of affiliative, dominance-related and sexual contexts, which differed depending upon the ages of the males involved. Mounting behaviour in this group was mainly initiated by adults. Juveniles mounted each other in affiliative contexts (during play and prior to grooming). Adult males mounted subadult and juvenile partners in a greater variety of sociosexual contexts (dominance/rank-related interactions; reconciliation following agonistic encounters, and sometimes as a prelude to receiving grooming). However, subadults and juveniles were never observed to mount adults. In one dyad, involving an adult male and a subadult partner, mounting was more frequent and prolonged, and included bouts of deep pelvic thrusting. Two mounts resulted in anal intromissions and, in 1 case, the subadult partner exhibited seminal emission. Given that the study took place during the annual mating peak period of R. roxellana, it is possible that this unusual male-male sexual activity was related to the absence of mating opportunities for those adults that were excluded from 1-male units. © 2018 S. Karger AG, Basel.

Females roam while males patrol: divergence in breeding season movements of pack-ice polar bears (Ursus maritimus).

PubMed

Laidre, Kristin L; Born, Erik W; Gurarie, Eliezer; Wiig, Øystein; Dietz, Rune; Stern, Harry

2013-02-07

Intraspecific differences in movement behaviour reflect different tactics used by individuals or sexes to favour strategies that maximize fitness. We report movement data collected from n = 23 adult male polar bears with novel ear-attached transmitters in two separate pack ice subpopulations over five breeding seasons. We compared movements with n = 26 concurrently tagged adult females, and analysed velocities, movement tortuosity, range sizes and habitat selection with respect to sex, reproductive status and body mass. There were no differences in 4-day displacements or sea ice habitat selection for sex or population. By contrast, adult females in all years and both populations had significantly more linear movements and significantly larger breeding range sizes than males. We hypothesized that differences were related to encounter rates, and used observed movement metrics to parametrize a simulation model of male-male and male-female encounter. The simulation showed that the more tortuous movement of males leads to significantly longer times to male-male encounter, while having little impact on male-female encounter. By contrast, linear movements of females are consistent with a prioritized search for sparsely distributed prey. These results suggest a possible mechanism for explaining the smaller breeding range sizes of some solitary male carnivores compared to females.

Mate competition and evolutionary outcomes in genetically modified zebrafish (Danio rerio).

PubMed

Howard, Richard D; Rohrer, Karl; Liu, Yiyang; Muir, William M

2015-05-01

Demonstrating relationships between sexual selection mechanisms and trait evolution is central to testing evolutionary theory. Using zebrafish, we found that wild-type males possessed a significant advantage in mate competition over transgenic RFP Glofish® males. In mating trials, wild-type males were aggressively superior to transgenic males in male-male chases and male-female chases; as a result, wild-type males sired 2.5× as many young as did transgenic males. In contrast, an earlier study demonstrated that female zebrafish preferred transgenic males as mates when mate competition was excluded experimentally. We tested the evolutionary consequence of this conflict between sexual selection mechanisms in a long-term study. The predicted loss of the transgenic phenotype was confirmed. More than 18,500 adults collected from 18 populations across 15 generations revealed that the frequency of the transgenic phenotype declined rapidly and was eliminated entirely in all but one population. Fitness component data for both sexes indicated that only male mating success differed between wild-type and transgenic individuals. Our predictive demographic model based on fitness components closely matched the rate of transgenic phenotype loss observed in the long-term study, thereby supporting its utility for studies assessing evolutionary outcomes of escaped or released genetically modified animals. © 2015 The Author(s).

Transcript levels of ten caste-related genes in adult diploid males of Melipona quadrifasciata (Hymenoptera, Apidae) - A comparison with haploid males, queens and workers.

PubMed

Borges, Andreia A; Humann, Fernanda C; Oliveira Campos, Lucio A; Tavares, Mara G; Hartfelder, Klaus

2011-10-01

In Hymenoptera, homozygosity at the sex locus results in the production of diploid males. In social species, these pose a double burden by having low fitness and drawing resources normally spent for increasing the work force of a colony. Yet, diploid males are of academic interest as they can elucidate effects of ploidy (normal males are haploid, whereas the female castes, the queens and workers, are diploid) on morphology and life history. Herein we investigated expression levels of ten caste-related genes in the stingless bee Melipona quadrifasciata, comparing newly emerged and 5-day-old diploid males with haploid males, queens and workers. In diploid males, transcript levels for dunce and paramyosin were increased during the first five days of adult life, while those for diacylglycerol kinase and the transcriptional co-repressor groucho diminished. Two general trends were apparent, (i) gene expression patterns in diploid males were overall more similar to haploid ones and workers than to queens, and (ii) in queens and workers, more genes were up-regulated after emergence until day five, whereas in diploid and especially so in haploid males more genes were down-regulated. This difference between the sexes may be related to longevity, which is much longer in females than in males.

No pain, no gain: Male plasticity in burrow digging according to female rejection in a sand-dwelling wolf spider.

PubMed

Carballo, Matilde; Baldenegro, Fabiana; Bollatti, Fedra; Peretti, Alfredo V; Aisenberg, Anita

2017-07-01

Behavioral plasticity allows individuals to reversibly respond to short-term variations in their ecological and social environment in order to maximize their fitness. Allocosa senex is a burrow-digging spider that inhabits the sandy coasts of South America. This species shows a reversal in typical sex roles expected in spiders: females are wanderers that visit males at their burrows and initiate courtship. They prefer males with long burrows for mating, and males prefer virgin over mated females. We tested whether female sexual rejection induced males to enlarge their burrows and if female reproductive status affected males' responses. We exposed males who had constructed burrows to: a) virgin females or b) mated females, (n=16 for each category). If female rejection occurred, we repeated the trial 48h later with the same female. As control, we maintained a group of males without female exposure (unexposed group, n=32). Rejected males enlarged their burrows more frequently and burrows were longer compared to unexposed males. However, frequency and length of enlargement did not differ according to female reproductive status. Males of A. senex showed plasticity in digging behavior in response to the availability of females, as a way to maximize the possibilities of future mating. Copyright © 2017 Elsevier B.V. All rights reserved.

Reversed sex change by widowed males in polygynous and protogynous fishes: female removal experiments in the field

NASA Astrophysics Data System (ADS)

Kuwamura, Tetsuo; Suzuki, Shohei; Kadota, Tatsuru

2011-12-01

Sex change, either protogyny (female to male) or protandry (male to female), is well known among fishes, but evidence of bidirectional sex change or reversed sex change in natural populations is still very limited. This is the first report on female removal experiments for polygnous and protogynous fish species to induce reversed sex change in the widowed males in the field. We removed all of the females and juveniles from the territories of dominant males in the cleaner wrasse Labroides dimidiatus (Labridae) and the rusty angelfish Centropyge ferrugata (Pomacanthidae) on the coral reefs of Okinawa. In both species, if new females or juveniles did not immigrate into the territories of the widowed males, some of them emigrated to form male-male pairs. When a male-male pair formed, the smaller, subordinate partner began to perform female sexual behaviours ( n = 4 in L. dimidiatus; n = 2 in C. ferrugata) and, finally, released eggs ( n = 1, respectively). Thus, the reversed sex change occurred in the widowed males according to the change of their social status. These results suggest that such female removal experiments will contribute to the discovery of reversed sex change in the field also in other polygnous and protogynous species.

Intra-population variation in behavior modification by the acanthocephalan Acanthocephalus dirus: are differences mediated by host condition?

PubMed

Caddigan, Sara C; Barkauskas, Rima T; Sparkes, Timothy C

2014-11-01

The acanthocephalan parasite Acanthocephalus dirus infects the freshwater isopod Caecidotea intermedius as an intermediate host before completing its life cycle in a fish. Male C. intermedius infected by A. dirus parasites are less likely to engage in mating behavior than uninfected males but there is a significant intra-population variation in the occurrence of this behavioral change. Previous studies on uninfected isopods have shown that glycogen content is a predictor of male mating behavior and we examined whether the intra-population variation in the mating behavior of infected male C. intermedius could be explained by this relationship. A field-based behavioral experiment was used to quantify intra-population variation in male mating behavior, which showed that 50% of infected males were responsive to females and 50% were not responsive. Biochemical analysis of responsive and non-responsive males revealed that glycogen content was a predictor of the mating behavior for uninfected males but was not a predictor of mating behavior for infected males. For infected males, parasite intensity was a predictor of mating behavior. Males that contained more A. dirus parasites were less likely to undergo modification of mating behavior. We propose that the intra-population variation in the mating behavior of infected C. intermedius identified in nature was not mediated by host condition.

The Effects of Food Limitation on Life History Tradeoffs in Pregnant Male Gulf Pipefish

PubMed Central

Paczolt, Kimberly A.; Jones, Adam G.

2015-01-01

Syngnathid fishes (pipefishes, seahorses and seadragons) are characterized by a unique mode of paternal care in which embryos develop on or in the male’s body, often within a structure known as a brood pouch. Evidence suggests that this pouch plays a role in mediating postcopulatory sexual selection and that males have some control over the events occurring within the pouch during the pregnancy. These observations lead to the prediction that males should invest differently in broods depending on the availability of food. Here, we use the Gulf pipefish to test this prediction by monitoring growth rate and offspring survivorship during the pregnancies of males under low- or high-food conditions. Our results show that pregnant males grow less rapidly on average than non-pregnant males, and pregnant males under low-food conditions grow less than pregnant males under high-food conditions. Offspring survivorship, on the other hand, does not differ between food treatments, suggesting that male Gulf pipefish sacrifice investment in somatic growth, and thus indirectly sacrifice future reproduction, in favor of current reproduction. However, a positive relationship between number of failed eggs and male growth rate in our low-food treatments suggests that undeveloped eggs reduce the pregnancy’s overall cost to the male compared to broods containing only viable offspring. PMID:25970284

Brain Transcriptional Profiles of Male Alternative Reproductive Tactics and Females in Bluegill Sunfish

PubMed Central

Partridge, Charlyn G.; MacManes, Matthew D.; Knapp, Rosemary; Neff, Bryan D.

2016-01-01

Bluegill sunfish (Lepomis macrochirus) are one of the classic systems for studying male alternative reproductive tactics (ARTs) in teleost fishes. In this species, there are two distinct life histories: parental and cuckolder, encompassing three reproductive tactics, parental, satellite, and sneaker. The parental life history is fixed, whereas individuals who enter the cuckolder life history transition from sneaker to satellite tactic as they grow. For this study, we used RNAseq to characterize the brain transcriptome of the three male tactics and females during spawning to identify gene ontology (GO) categories and potential candidate genes associated with each tactic. We found that sneaker males had higher levels of gene expression differentiation compared to the other two male tactics. Sneaker males also had higher expression in ionotropic glutamate receptor genes, specifically AMPA receptors, compared to other males, which may be important for increased spatial working memory while attempting to cuckold parental males at their nests. Larger differences in gene expression also occurred among male tactics than between males and females. We found significant expression differences in several candidate genes that were previously identified in other species with ARTs and suggest a previously undescribed role for cAMP-responsive element modulator (crem) in influencing parental male behaviors during spawning. PMID:27907106

Death feigning in the face of sexual cannibalism

PubMed Central

Bilde, Trine; Tuni, Cristina; Elsayed, Rehab; Pekár, Stano; Toft, Søren

2005-01-01

Pre-copulatory sexual cannibalism by females affects male and female reproductive success in profoundly different ways, with the females benefiting from a meal and the male facing the risk of not reproducing at all. This sexual conflict predicts evolution of traits to avoid cannibalism and ensure male reproductive success. We show that males of the nuptial gift-giving spider Pisaura mirabilis display a remarkable death feigning behaviour—thanatosis—as part of the courtship prior to mating with potentially cannibalistic females. Thanatosis is a widespread anti-predator strategy; however, it is exceptional in the context of sexual selection. When the female approached a gift-displaying male, she usually showed interest in the gift but would sometimes attack the male, and at this potentially dangerous moment the male could ‘drop dead’. When entering thanatosis, the male would collapse and remain completely motionless while retaining hold of the gift so it was held simultaneously by both mates. When the female initiated consumption of the gift, the male cautiously ‘came to life’ and initiated copulation. Death feigning males were more successful in gaining copulations, but did not have prolonged copulations. We propose that death feigning evolved as an adaptive male mating strategy in conjunction with nuptial gift giving under the risk of being victimized by females. PMID:17148316

Insurance coverage for male infertility care in the United States

PubMed Central

Dupree, James M

2016-01-01

Infertility is a common condition experienced by many men and women, and treatments are expensive. The World Health Organization and American Society of Reproductive Medicine define infertility as a disease, yet private companies infrequently offer insurance coverage for infertility treatments. This is despite the clear role that healthcare insurance plays in ensuring access to care and minimizing the financial burden of expensive services. In this review, we assess the current knowledge of how male infertility care is covered by insurance in the United States. We begin with an appraisal of the costs of male infertility care, then examine the state insurance laws relevant to male infertility, and close with a discussion of why insurance coverage for male infertility is important to both men and women. Importantly, we found that despite infertility being classified as a disease and males contributing to almost half of all infertility cases, coverage for male infertility is often excluded from health insurance laws. Excluding coverage for male infertility places an undue burden on their female partners. In addition, excluding care for male infertility risks missing opportunities to diagnose important health conditions and identify reversible or irreversible causes of male infertility. Policymakers should consider providing equal coverage for male and female infertility care in future health insurance laws. PMID:27030084

Female sticklebacks use male coloration in mate choice and hence avoid parasitized males

NASA Astrophysics Data System (ADS)

Milinski, Manfred; Bakker, Theo C. M.

1990-03-01

AN important problem in evolutionary biology since the time of Darwin has been to understand why females preferentially mate with males handicapped by secondary sexual ornaments1-3. One hypothesis of sexual selection theory is that these ornaments reliably reveal the male's condition4-6, which can be affected for example by parasites4,7-13. Here we show that in the three-spined stickleback (Gasterosteus aculeatus) the intensity of male red breeding coloration positively correlates with physical condition. Gravid females base their active mate choice on the intensity of the male's red coloration. Choice experiments under green light prevent the use of red colour cues by females, and males that were previously preferred are now chosen no more than randomly, although the courtship behaviour of the males remains unchanged. Parasitieation causes a deterioration in the males' condition and a decrease in the intensity of their red coloration. Tests under both lighting conditions reveal that the females recognize the formerly parasitized males by the lower intensity of their breeding coloration. Female sticklebacks possibly select a male with a good capacity for paternal care14 but if there is additive genetic variation for parasite resistance, then they might also select for resistance genes, as proposed by Hamilton and Zuk4.

Brain Transcriptional Profiles of Male Alternative Reproductive Tactics and Females in Bluegill Sunfish.

PubMed

Partridge, Charlyn G; MacManes, Matthew D; Knapp, Rosemary; Neff, Bryan D

2016-01-01

Bluegill sunfish (Lepomis macrochirus) are one of the classic systems for studying male alternative reproductive tactics (ARTs) in teleost fishes. In this species, there are two distinct life histories: parental and cuckolder, encompassing three reproductive tactics, parental, satellite, and sneaker. The parental life history is fixed, whereas individuals who enter the cuckolder life history transition from sneaker to satellite tactic as they grow. For this study, we used RNAseq to characterize the brain transcriptome of the three male tactics and females during spawning to identify gene ontology (GO) categories and potential candidate genes associated with each tactic. We found that sneaker males had higher levels of gene expression differentiation compared to the other two male tactics. Sneaker males also had higher expression in ionotropic glutamate receptor genes, specifically AMPA receptors, compared to other males, which may be important for increased spatial working memory while attempting to cuckold parental males at their nests. Larger differences in gene expression also occurred among male tactics than between males and females. We found significant expression differences in several candidate genes that were previously identified in other species with ARTs and suggest a previously undescribed role for cAMP-responsive element modulator (crem) in influencing parental male behaviors during spawning.

Sexual Fate Reprogramming in the Steroid-Induced Bi-Directional Sex Change in the Protogynous Orange-Spotted Grouper, Epinephelus coioides.

PubMed

Wu, Guan-Chung; Tey, Wei-Guan; Li, Hau-Wen; Chang, Ching-Fong

2015-01-01

Androgen administration has been widely used for masculinization in fish. The mechanism of the sex change in sexual fate regulation is not clear. Oral administration or pellet implantation was applied. We orally applied an aromatase inhibitor (AI, to decrease estrogen levels) and 17α-methyltestosterone (MT, to increase androgen levels) to induce masculinization to clarify the mechanism of the sex change in the protogynous orange-spotted grouper. After 3 mo of AI/MT administration, male characteristics were observed in the female-to-male sex change fish. These male characteristics included increased plasma 11-ketotestosterone (11-KT), decreased estradiol (E2) levels, increased male-related gene (dmrt1, sox9, and cyp11b2) expression, and decreased female-related gene (figla, foxl2, and cyp19a1a) expression. However, the reduced male characteristics and male-to-female sex change occurred after AI/MT-termination in the AI- and MT-induced maleness. Furthermore, the MT-induced oocyte-depleted follicle cells (from MT-implantation) had increased proliferating activity, and the sexual fate in a portion of female gonadal soma cells was altered to male function during the female-to-male sex change. In contrast, the gonadal soma cells were not proliferative during the early process of the male-to-female sex change. Additionally, the male gonadal soma cells did not alter to female function during the male-to-female sex change in the AI/MT-terminated fish. After MT termination in the male-to-female sex-changed fish, the differentiated male germ cells showed increased proliferating activities together with dormancy and did not show characteristics of both sexes in the early germ cells. In conclusion, these findings indicate for the first time in a single species that the mechanism involved in the replacement of soma cells is different between the female-to-male and male-to-female sex change processes in grouper. These results also demonstrate that sexual fate determination (secondary sex determination) is regulated by endogenous sex steroid levels.

Sexual Fate Reprogramming in the Steroid-Induced Bi-Directional Sex Change in the Protogynous Orange-Spotted Grouper, Epinephelus coioides

PubMed Central

Wu, Guan-Chung; Tey, Wei-Guan; Li, Hau-Wen; Chang, Ching-Fong

2015-01-01

Androgen administration has been widely used for masculinization in fish. The mechanism of the sex change in sexual fate regulation is not clear. Oral administration or pellet implantation was applied. We orally applied an aromatase inhibitor (AI, to decrease estrogen levels) and 17α-methyltestosterone (MT, to increase androgen levels) to induce masculinization to clarify the mechanism of the sex change in the protogynous orange-spotted grouper. After 3 mo of AI/MT administration, male characteristics were observed in the female-to-male sex change fish. These male characteristics included increased plasma 11-ketotestosterone (11-KT), decreased estradiol (E2) levels, increased male-related gene (dmrt1, sox9, and cyp11b2) expression, and decreased female-related gene (figla, foxl2, and cyp19a1a) expression. However, the reduced male characteristics and male-to-female sex change occurred after AI/MT-termination in the AI- and MT-induced maleness. Furthermore, the MT-induced oocyte-depleted follicle cells (from MT-implantation) had increased proliferating activity, and the sexual fate in a portion of female gonadal soma cells was altered to male function during the female-to-male sex change. In contrast, the gonadal soma cells were not proliferative during the early process of the male-to-female sex change. Additionally, the male gonadal soma cells did not alter to female function during the male-to-female sex change in the AI/MT-terminated fish. After MT termination in the male-to-female sex-changed fish, the differentiated male germ cells showed increased proliferating activities together with dormancy and did not show characteristics of both sexes in the early germ cells. In conclusion, these findings indicate for the first time in a single species that the mechanism involved in the replacement of soma cells is different between the female-to-male and male-to-female sex change processes in grouper. These results also demonstrate that sexual fate determination (secondary sex determination) is regulated by endogenous sex steroid levels. PMID:26714271

"Brothers Gonna Work It Out:" Understanding the Pedagogic Performance of African American Male Teachers Working with African American Male Students

ERIC Educational Resources Information Center

Brown, Anthony L.

2009-01-01

Drawing from ethnographic data, this paper explores how African American male teachers working with African American male students performed their pedagogy. This paper highlights how teachers' understanding of African American males social and educational needs shaped their pedagogical performance. Interestingly however, teachers' performance was…

The Success of Vocationally Trained Women in Traditionally Male Occupations.

ERIC Educational Resources Information Center

Pucel, David J.

A study was conducted to examine the ability of women who enroll in traditionally male occupations to receive equal training and equal employment benefits to those of males enrolled in the same programs. (A traditionally male occupation was defined as an occupation which employed 80% or more males.) The eight programs included in the study were…

Mortal Kombat: The Effects of Violent Video Technology on Males' Hostility and Cardiovascular Responding.

ERIC Educational Resources Information Center

Ballard, Mary E.; Wiest, J. Rose

A study examined differences in cardiovascular (CV) reactions and hostility following non-violent play and violent video game play. Subjects were 30 male college undergraduate students. Only male subjects were used because most video games are male oriented, males frequent videogame arcades more often than females, and the gender gap in video game…

Comparing Female and Male Perpetrators' Modus Operandi: Victims' Reports of Sexual Abuse.

ERIC Educational Resources Information Center

Kaufman, Keith L.; And Others

1995-01-01

Investigated similarities and differences in modus operandi of female and male child sexual abusers by comparing victims of female and male perpetrators. Females were more often involved with males in co-offender situations and were more likely to exploit victims. Males were more sexually invasive and more likely to use bribes to obtain victim…

Physiologic Responses of Able-Bodied and Paraplegic Males to Maximal Arm Ergometry.

ERIC Educational Resources Information Center

Israel, Richard G.; And Others

A study compared physiologic responses of healthy paraplegic males to those of healthy, able-bodied males during maximal arm ergometry. Fifteen able-bodied, healthy adult males and 13 healthy adult male paraplegics followed an exercise program involving heart rate, increased exercise loads, and oxygen uptake. Results from an analysis of the data…

Coming of Age: African American Male Rites-of-Passage.

ERIC Educational Resources Information Center

Hill, Paul, Jr.

An overview is provided of issues confronting the African American male, along with a strategy to nurture a new generation of African American males. Chapters 1 and 2 focus on the social status and new demographics of the African American male and the external threats that are devastating to the African American male and the African American…

Gifted Male Readers: Current Understandings and Suggestions for Future Research

ERIC Educational Resources Information Center

Pagnani, Alexander R.

2013-01-01

Research literature concerning gifted male readers relies primarily on more extensive bodies of work regarding gifted males and male readers. Studied as a whole, the two halves portray a worrisome state of affairs for gifted male readers, who lag behind their female counterparts in the same patterns found across the ability spectrum. This literacy…

Help-Seeking among Male Victims of Partner Abuse: Men's Hard Times

ERIC Educational Resources Information Center

Tsui, Venus; Cheung, Monit; Leung, Patrick

2010-01-01

Sixty-eight agency representatives in the United States completed a survey to identify issues of male victims in partner abuse: half referenced responses from male clients and the other half responses from male victims who were their family members, friends, colleagues, or themselves. Almost 25% revealed that male victims did not utilize social…

Subacute Sclerosing Panencephalitis

MedlinePlus

... There is a higher incidence among males than females (male/female: 3/1). Most youngsters with SSPE have a ... There is a higher incidence among males than females (male/female: 3/1). Most youngsters with SSPE ...

Genetic biases for showy males: Are some genetic systems especially conducive to sexual selection?

PubMed Central

Reeve, Hudson Kern; Pfennig, David W.

2003-01-01

Male secondary sexual characters (conspicuous ornaments, signals, colors) are among nature's most striking features. Yet, it is unclear why certain groups of organisms are more likely than others to evolve these traits. One explanation for such taxonomic biases is that some genetic systems may be especially conducive to sexual selection. Here, we present theory and simulation results demonstrating that rare alleles encoding either male ornaments or female preferences for those ornaments are better protected against random loss in species with ZZ/ZW or ZZ/ZO sex chromosome systems (male homogamety) than in species with XX/XY or XX/XO systems (male heterogamety). Moreover, this protection is much stronger in diploid than haplodiploid species. We also present empirical data showing that male secondary sexual characters are better developed in diploid than haplodiploid species and in diploid species with male homogamety than in those with male heterogamety. Thus, taxonomic biases for showy males may stem from differences in sex chromosome systems. PMID:12540829

EGFR ligands exert diverging effects on male reproductive organs.

PubMed

Schneider, Marlon R; Gratao, Ana A; Dahlhoff, Maik; Boersma, Auke; Hrabé de Angelis, Martin; Hoang-Vu, Cuong; Wolf, Eckhard; Klonisch, Thomas

2010-02-01

While the EGFR and most of its ligands are expressed in the male reproductive tract, their functions in male reproduction are poorly understood. Interestingly, male transgenic mice overexpressing EGF are sterile, and transgenic mice overexpressing TGFA, another EGFR ligand, show an enlarged coagulation gland (anterior prostate) due to severe hyperplasia with focal dysplasia. We studied the male reproductive tract of transgenic mice overexpressing betacellulin (BTC-tg) under the control of a promoter conferring widespread transgene expression. Despite strong overexpression of BTC in different parts of the male reproductive tract, the gross appearance and histology of the reproductive organs of BTC-tg males were normal and the same were true for sperm parameters and the in vitro fertilization rate. Collectively, our findings demonstrate that excess of BTC exerts no deleterious effects on the structure or function of the male reproductive tract in mice and indicates unique, non-overlapping functions of specific EGFR ligands in male reproduction. Copyright 2009 Elsevier Inc. All rights reserved.

Male scent-marking pheromone of Bombus ardens ardens (Hymenoptera; Apidae) attracts both conspecific queens and males

NASA Astrophysics Data System (ADS)

Kubo, Ryohei; Harano, Ken-ichi; Ono, Masato

2017-10-01

To explore the role of the volatiles emitted from male labial gland (LG) of the bumblebee Bombus ardens ardens, we investigated the responses of virgin queens and males to volatiles using a gas chromatography-electroantennographic detector (GC-EAD) system and Y-tube olfactometer. GC-EAD analysis revealed that citronellol, the main compound detected in the male LG, caused clear electrophysiological responses in the antennae of B. a. ardens virgin queens and males although two minor compounds elicited antennal responses when applied in a high concentration. Behavioral tests using a Y-tube olfactometer showed that queens and males were significantly attracted to both LG extracts and citronellol more than to the solvent alone. This is the first study to demonstrate that citronellol as a major compound of male scent-marking pheromone in B. a. ardens functions as a sex attractant for queens. The results also suggest that this compound has another function as a trail marker used by males.

Seasonal resource value and male size influence male aggressive interactions in the leaf footed cactus bug, Narnia femorata.

PubMed

Nolen, Zachary J; Allen, Pablo E; Miller, Christine W

2017-05-01

In animal contests, resource value (the quality of a given resource) and resource holding potential (a male's absolute fighting ability) are two important factors determining the level of engagement and outcome of contests. Few studies have tested these factors simultaneously. Here, we investigated whether natural, seasonal differences in cactus phenology (fruit quality) influence interactions between males in the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae). We also considered whether males were more likely to interact when they were similar in size, as predicted by theory. Finally, we examined if male size relative to the size of an opponent predicted competitive success. We found that males have more interactions on cactus with high value ripe fruit, as we predicted. Further, we found that males that were closer in size were more likely to interact, and larger males were more likely to become dominant. Copyright © 2017 Elsevier B.V. All rights reserved.

From ornament to armament or loss of function? Breeding plumage acquisition in a genetically monogamous bird.

PubMed

Fan, Marie; Teunissen, Niki; Hall, Michelle L; Hidalgo Aranzamendi, Nataly; Kingma, Sjouke A; Roast, Michael; Delhey, Kaspar; Peters, Anne

2018-06-25

The evolution of conspicuous male traits is thought to be driven by female mate choice or male-male competition. These two mechanisms are often viewed as distinct processes, with most studies focusing on female choice. However, both mechanisms of sexual selection can act simultaneously on the same trait (i.e., dual function) and/or interact in a synergistic or conflicting way. Dual-function traits are commonly assumed to originate through male-male competition before being used in female choice; yet, most studies focusing on such traits could not determine the direction of change, lacking phylogenetic information. We investigated the role of conspicuous male seasonal plumage in male-male competitive interactions in the purple-crowned fairy-wren Malurus coronatus, a cooperatively breeding bird. Male breeding plumage in most Malurus species is selected by female choice through extra-pair mate choice, but unlike its congeners, M. coronatus is genetically monogamous, and females do not seem to choose males based on breeding plumage acquisition. Our study shows that, within groups, subordinate males that were older, and therefore higher-ranked in the queue for breeder position inheritance, produced a more complete breeding plumage. In line with this, subordinate males that were older and/or displayed a more complete breeding plumage were more successful in competitively acquiring a breeder position. A role as a signal of competitive ability was experimentally confirmed by presenting models of males: in breeding colours, these received more aggression from resident breeder males than in nonbreeding colours, but elicited limited response from females, consistent with competitors in breeding plumage being perceived as a bigger threat to the breeder male. The role of the conspicuous breeding plumage in mediating male-male interactions might account for its presence in this genetically monogamous species. As phylogenetic reconstructions suggest a past female choice function in M. coronatus, this could represent a sexual trait that shifted functions, or a dual-function trait that lost one function. These evolutionary scenarios imply that intra- and intersexual functions of ornaments may be gained or lost independently and offer new perspectives in understanding the complex dynamics of sexual selection. © 2018 The Authors. Journal of Animal Ecology © 2018 British Ecological Society.

Plasticity of signaling and mate choice in a trilling species of the Mecopoda complex (Orthoptera: Tettigoniidae).

PubMed

Krobath, I; Römer, H; Hartbauer, M

2017-01-01

Males of a trilling species in the Mecopoda complex produce conspicuous calling songs that consist of two motifs: an amplitude-modulated motif with alternating loud and soft segments (AM-motif) and a continuous, high-intensity trill. The function of these song motifs for female attraction and competition between males was investigated. We tested the hypothesis that males modify their signaling behavior depending on the social environment (presence/absence of females or rival males) when they compete for mates. Therefore, we analyzed acoustic signaling of males in three different situations: (1) solo singing, (2) acoustic interaction with another male, and (3) singing in the presence of a female. In addition, the preference of females for these song motifs and further song parameters was studied in two-choice experiments. As expected, females showed a preference for conspicuous and loud song elements, but nevertheless, males increased the proportion of the AM-motif in the presence of a female. In acoustic interactions, males reduced bout duration significantly compared to both other situations. However, song bouts in this situation still overlapped more than expected by chance, which indicates intentionally simultaneous singing. A multivariate statistical analysis revealed that the proportion of the AM-motif and the duration of loud segments within the AM-motif allow a reliable prediction of whether males sing in isolation, compete with another male, or sing in the presence of a female. These results indicate that the AM-motif plays a dominant role especially in close-range courtship and that males are challenged in finding a balance between attracting females and saving energy during repeated acoustic interactions. Males of acoustic insects often produce conspicuous calling songs that have a dual function in male-male competition and mate attraction. High signal amplitudes and signal rates are associated with high energetic costs for signal production. We would therefore predict that males adjust their signaling behavior according to their perception of the social context. Here we studied signal production and mate choice in a katydid, where males switch between loud and soft song segments in a dynamic way. Additionally, we examined the attractiveness of different song elements in female choice tests. Our results show how males of this katydid deal with the conflict of remaining attractive for females and competing with a costly signal with rivals.

Are attractive male crickets better able to pay the costs of an immune challenge?

PubMed Central

Telemeco, Melissa S.C.; Bartholomay, Lyric C.

2015-01-01

Reproduction and immunity are fitness-related traits that trade-off with each other. Parasite-mediated theories of sexual selection suggest, however, that higher-quality males should suffer smaller costs to reproduction-related traits and behaviours (e.g., sexual display) from an immune challenge because these males possess more resources with which to deal with the challenge. We used Gryllus texensis field crickets to test the prediction that attractive males should better maintain the performance of fitness-related traits (e.g., calling effort) in the face of an immune challenge compared with unattractive males. We found no support for our original predictions. However, that immune activation causes attractive males to significantly increase their calling effort compared with unattractive males suggests that these males might terminally invest in order to compensate for decreased future reproduction. PMID:26713249

Sex-role reversed nuptial feeding reduces male kleptoparasitism of females in Zeus bugs (Heteroptera; Veliidae)

PubMed Central

Arnqvist, Göran; Jones, Therésa M; Elgar, Mark A

2006-01-01

Males of a variety of taxa occasionally steal food secured by their mates. In some spiders and insects, males rely entirely on this form of intraspecific kleptoparasitism for their subsistence. However, this male strategy may be costly for females and a variety of different female counteradaptations have been proposed. In Zeus bugs (Phoreticovelia spp.), males ride on the back of their mates for extended periods and females produce a gland secretion that males feed on. By experimentally occluding the dorsal glands in females and varying food availability, we show that nuptial feeding by females reduces the extent to which the males kleptoparasitize their mates. We suggest that females have, at least in part, evolved this unique form of nuptial feeding as a counteradaptation to reduce the rate of kleptoparasitism by males. PMID:17148270

Stability and value of male care for offspring: is it worth only half the trouble?

PubMed

Fromhage, Lutz; McNamara, John M; Houston, Alasdair I

2007-06-22

Models of parental investment often assume a trade-off for males between providing care and seeking additional mating opportunities. It is not obvious, however, how such additional matings should be accounted for in a consistent population model, because deserting males might increase their fertilization success at the cost of either caring males, other deserting males or both. Here, we present a game theory model that addresses all of these possibilities in a general way. In contrast to earlier work, we find that the source of deserting males' additional matings is irrelevant to the evolutionary stability of male care. We reject the claim that fitness gains through male care are intrinsically less valuable than those through desertion, and that the former must therefore be down-weighted by 1/2 when compared with the latter.

Attraction to mammals of male mosquitoes with special reference to Aedes diantaeus in Sweden.

PubMed

Jaenson, T G

1985-06-01

During investigations in central Sweden on the ecology of mosquito vectors of Ockelbo disease, large numbers of Aedes diantaeus males and lesser numbers of Ae. communis, Ae. excrucians and Ae. intrudens males were captured in animal-baited (rabbit, guinea pig, hen, dove, unbaited control) suction- and net-traps. In the five suction-traps, 57% of the diantaeus captured (N = 1,896) were males. Although the guinea pig-baited suction-trap captured the highest mean number of diantaeus males, data showed that these males, like the females, were mainly attracted to the largest mammal, i.e., the rabbit. These males assembled in the vicinity of the rabbit presumably to intercept females coming to feed. The net-trap data showed that orientation by the males to the rabbit presumably involved olfactory cues emanating from the mammal.

Why Do Cuckolded Males Provide Paternal Care?

PubMed Central

Griffin, Ashleigh S.; Alonzo, Suzanne H.; Cornwallis, Charlie K.

2013-01-01

In most species, males do not abandon offspring or reduce paternal care when they are cuckolded by other males. This apparent lack of adjustment of paternal investment with the likelihood of paternity presents a potential challenge to our understanding of what drives selection for paternal care. In a comparative analysis across birds, fish, mammals, and insects we identify key factors that explain why cuckolded males in many species do not reduce paternal care. Specifically, we show that cuckolded males only reduce paternal investment if both the costs of caring are relatively high and there is a high risk of cuckoldry. Under these circumstances, selection is expected to favour males that reduce paternal effort in response to cuckoldry. In many species, however, these conditions are not satisfied and tolerant males have outcompeted males that abandon young. PMID:23555193

Factors affecting the reproductive success of dominant male meerkats.

PubMed

Spong, Göran F; Hodge, Sarah J; Young, Andrew J; Clutton-Brock, Tim H

2008-05-01

Identifying traits that affect the reproductive success of individuals is fundamental for our understanding of evolutionary processes. In cooperative breeders, a dominant male typically restricts mating access to the dominant female for extended periods, resulting in pronounced variation in reproductive success among males. This may result in strong selection for traits that increase the likelihood of dominance acquisition, dominance retention and reproductive rates while dominant. However, despite considerable research on reproductive skew, few studies have explored the factors that influence these three processes among males in cooperative species. Here we use genetic, behavioural and demographic data to investigate the factors affecting reproductive success in dominant male meerkats (Suricata suricatta). Our data show that dominant males sire the majority of all offspring surviving to 1 year. A male's likelihood of becoming dominant is strongly influenced by age, but not by weight. Tenure length and reproductive rate, both important components of dominant male reproductive success, are largely affected by group size and composition, rather than individual traits. Dominant males in large groups have longer tenures, but after this effect is controlled, male tenure length also correlates negatively to the number of adult females in the group. Male reproductive rate also declines as the number of intra- and extra-group competitors increases. As the time spent in the dominant position and reproductive rate while dominant explain > 80% of the total variance in reproductive success, group composition thus has major implications for male reproductive success.

The white gene of Drosophila melanogaster encodes a protein with a role in courtship behavior.

PubMed

Anaka, Matthew; MacDonald, C Danielle; Barkova, Eva; Simon, Karl; Rostom, Reem; Godoy, Ruth A; Haigh, Andrew J; Meinertzhagen, Ian A; Lloyd, Vett

2008-01-01

The white gene of Drosophila melanogaster has been extensively studied, yet it is still not understood how its ectopic overexpression induces male-male courtship. To investigate the cellular basis of this behavior, we examined the sexual behavior of several classes of mutants. We find that male-male courtship is seen not only in flies overexpressing the white gene, but also in mutants expected to have mislocalized White protein. This finding confirms that mislocalizing White transporter in the cells in which it is normally expressed will produce male-male courtship behaviors; the courtship behavior is not an indirect consequence of aberrant physiological changes elsewhere in the body. Male-male courtship is also seen in some mutants with altered monoamine metabolism and deficits in learning and memory, but can be distinguished from that produced by White mislocalization by its reduced intensity and locomotor activity. Double mutants overexpressing white and with mutations in genes for serotonergic neurons suggest that male-male courtship produced by mislocalizing White may not be mediated exclusively by serotonergic neurons. We also find decreased olfactory learning in white mutants and in individuals with mutations in the genes for White's binding partners, brown and scarlet. Finally, in cultured Drosophila and mammalian cells, the White transporter is found in the endosomal compartment. The additional genes identified here as being involved in male-male courtship increase the repertoire of mutations available to study sexual behavior in Drosophila.

Celluloid devils: a research study of male nurses in feature films.

PubMed

Stanley, David

2012-11-01

To report a study of how male nurses are portrayed in feature films. It was hypothesized that male nurses are frequently portrayed negatively or stereotypically in the film media, potentially having a negative impact on male nurse recruitment and the public's perception of male nurses. An interpretive, qualitative methodology guided by insights into hegemonic masculinity and structured around a set of collective case studies (films) was used to examine the portrayal of male nurses in feature films made in the Western world from 1900 to 2007. Over 36,000 feature film synopses were reviewed (via CINAHL, ProQuest and relevant movie-specific literature) for the keyword 'nurse' and 'nursing' with an additional search for films from 1900 to 2010 for the word 'male nurse'. Identified films were labelled as 'cases' and analysed collectively to determine key attributes related to men in nursing and explore them for the emergence of concepts and themes related to the image of male nurses in films. A total of 13 relevant cases (feature films) were identified with 12 being made in the USA. Most films portrayed male nurses negatively and in ways opposed to hegemonic masculinity, as effeminate, homosexual, homicidal, corrupt or incompetent. Few film images of male nurses show them in traditional masculine roles or as clinically competent or self-confident professionals.   Feature films predominantly portray male nurses negatively. Given the popularity of feature films, there may be negative effects on recruitment and on the public's perception of male nurses. © 2012 Blackwell Publishing Ltd.

The influence of male takeovers on female dispersal in Colobus vellerosus.

PubMed

Sicotte, Pascale; Teichroeb, Julie A; Vayro, Josie V; Fox, Stephanie A; Bădescu, Iulia; Wikberg, Eva C

2017-07-01

Male takeovers affect male tenure, female mate choice and ultimately, individual reproductive success in group-living primates. In social systems with female philopatry and high male reproductive skew, male takeovers largely determine female mate choice, whereas in species with female dispersal, females have the option of deserting a new male. We focused on a species with facultative female dispersal to investigate which factors promote female desertion of males after takeover, using 15 cases (12 for which we have complete data on the takeover process and the female dispersal outcome). These cases took place in nine groups of Colobus vellerosus between 2001 and 2013 at the Boabeng-Fiema Monkey Sanctuary, Ghana. Quick takeovers were usually achieved by single adult males and were never followed by female dispersal. Slow takeovers involved several males, and these takeovers were regularly accompanied by female emigration. Infant attacks and infanticide by males occurred during both kinds of takeovers, but females with dependent offspring never dispersed, regardless of whether their infant was attacked or killed by the new male(s). Subadult females, who were not constrained by the presence of infants, dispersed more often after slow takeovers than after quick takeovers. Whether female dispersal post-takeover is an expression of female mate choice, or occurs to avoid the social upheaval surrounding slow takeovers, remains to be investigated. Am. J. Primatol. 79:e22436, 2017. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Strategic growth decisions in helper cichlids.

PubMed Central

Heg, Dik; Bender, Nicole; Hamilton, Ian

2004-01-01

Recently, it has been shown that group-living subordinate clownfish Amphiprion percula increase their growth rate after acquiring the dominant breeder male position in the group. Evidence was found for strategic growth adjustments of subordinate fishes depending on the threat of eviction, i.e. subordinates adjust their growth rates so they remain smaller than the dominant fish and thereby limit the threat of being expelled from the territory. However, it is impossible to exclude several alternative factors that potentially could have influenced the observed changes in growth, owing to the nature of that experiment (removing the second-ranking fish--the breeder male--caused the third-ranking fish to change sex to become breeder male and change rank). We studied strategic growth decisions in the group-living Lake Tanganyika cichlid Neolamprologus pulcher under controlled laboratory conditions with ad libitum food availability. First, we show that male breeders grow faster than subordinate male helpers of the same initial size and confirm that N. pulcher shows status-dependent growth. Second, we improved on the experimental design by not removing the dominant breeder male in the group; instead we replaced the breeder male with a new breeder male in a full factorial design and measured growth of the subordinate male helpers is a function of the size difference with the old and the new breeder male. As predicted, male helpers showed strategic growth adjustments, i.e. growing faster when the size difference with the breeder male is large. Strategic growth adjustments were less pronounced than status-dependent growth adjustments. PMID:15801617

Strategic growth decisions in helper cichlids.

PubMed

Heg, Dik; Bender, Nicole; Hamilton, Ian

2004-12-07

Recently, it has been shown that group-living subordinate clownfish Amphiprion percula increase their growth rate after acquiring the dominant breeder male position in the group. Evidence was found for strategic growth adjustments of subordinate fishes depending on the threat of eviction, i.e. subordinates adjust their growth rates so they remain smaller than the dominant fish and thereby limit the threat of being expelled from the territory. However, it is impossible to exclude several alternative factors that potentially could have influenced the observed changes in growth, owing to the nature of that experiment (removing the second-ranking fish--the breeder male--caused the third-ranking fish to change sex to become breeder male and change rank). We studied strategic growth decisions in the group-living Lake Tanganyika cichlid Neolamprologus pulcher under controlled laboratory conditions with ad libitum food availability. First, we show that male breeders grow faster than subordinate male helpers of the same initial size and confirm that N. pulcher shows status-dependent growth. Second, we improved on the experimental design by not removing the dominant breeder male in the group; instead we replaced the breeder male with a new breeder male in a full factorial design and measured growth of the subordinate male helpers is a function of the size difference with the old and the new breeder male. As predicted, male helpers showed strategic growth adjustments, i.e. growing faster when the size difference with the breeder male is large. Strategic growth adjustments were less pronounced than status-dependent growth adjustments.

Effect of mating activity and dominance rank on male masturbation among free-ranging male rhesus macaques

PubMed Central

Dubuc, Constance; Coyne, Sean P.; Maestripieri, Dario

2013-01-01

The adaptive function of male masturbation is still poorly understood, despite its high prevalence in humans and other animals. In non-human primates, male masturbation is most frequent among anthropoid monkeys and apes living in multimale-multifemale groups with a promiscuous mating system. In these species, male masturbation may be a non-functional by-product of high sexual arousal or be adaptive by providing advantages in terms of sperm competition or by decreasing the risk of sexually transmitted infections. We investigated the possible functional significance of male masturbation using behavioral data collected on 21 free-ranging male rhesus macaques (Macaca mulatta) at the peak of the mating season. We found some evidence that masturbation is linked to low mating opportunities: regardless of rank, males were most likely to be observed masturbating on days in which they were not observed mating, and lower-ranking males mated less and tended to masturbate more frequently than higher-ranking males. These results echo the findings obtained for two other species of macaques, but contrast those obtained in red colobus monkeys (Procolobus badius) and Cape ground squirrels (Xerus inauris). Interestingly, however, male masturbation events ended with ejaculation in only 15% of the observed masturbation time, suggesting that new hypotheses are needed to explain masturbation in this species. More studies are needed to establish whether male masturbation is adaptive and whether it serves similar or different functions in different sexually promiscuous species. PMID:24187414

Effect of mating activity and dominance rank on male masturbation among free-ranging male rhesus macaques.

PubMed

Dubuc, Constance; Coyne, Sean P; Maestripieri, Dario

2013-11-01

The adaptive function of male masturbation is still poorly understood, despite its high prevalence in humans and other animals. In non-human primates, male masturbation is most frequent among anthropoid monkeys and apes living in multimale-multifemale groups with a promiscuous mating system. In these species, male masturbation may be a non-functional by-product of high sexual arousal or be adaptive by providing advantages in terms of sperm competition or by decreasing the risk of sexually transmitted infections. We investigated the possible functional significance of male masturbation using behavioral data collected on 21 free-ranging male rhesus macaques ( Macaca mulatta ) at the peak of the mating season. We found some evidence that masturbation is linked to low mating opportunities: regardless of rank, males were most likely to be observed masturbating on days in which they were not observed mating, and lower-ranking males mated less and tended to masturbate more frequently than higher-ranking males. These results echo the findings obtained for two other species of macaques, but contrast those obtained in red colobus monkeys ( Procolobus badius ) and Cape ground squirrels ( Xerus inauris ). Interestingly, however, male masturbation events ended with ejaculation in only 15% of the observed masturbation time, suggesting that new hypotheses are needed to explain masturbation in this species. More studies are needed to establish whether male masturbation is adaptive and whether it serves similar or different functions in different sexually promiscuous species.

Hybrid male sterility between Drosophila willistoni species is caused by male failure to transfer sperm during copulation.

PubMed

Civetta, Alberto; Gaudreau, Chelsea

2015-05-01

The biological concept of species stresses the importance of understanding what mechanisms maintain species reproductively isolated from each other. Often such mechanisms are divided into premating and postmating, with the latest being the result of either prezygotic or postzygotic isolation barriers. Drosophila willistoni quechua and Drosophila willistoni willistoni are two subspecies that experience reproductive isolation. When a D. w. quechua female is crossed with a D. w. willistoni male, the hybrid males (F1QW) are unable to father progeny; however, the reciprocal cross produces fertile hybrids. Thus, the mechanism of isolation is unidirectional hybrid male sterility. However, the sterile F1QW males contain large amounts of motile sperm. Here we explore whether pre-copulatory or post-copulatory pre-zygotic mechanisms serve as major deterrents in the ability of F1QW males to father progeny. Comparisons of parental and hybrid males copulation durations showed no significant reduction in copulation duration of F1QW males. Interrupted copulations of the parental species confirmed that sperm transfer occurs before the minimum copulation duration registered for F1QW males. However, we found that when females mate with F1QW males, sperm is not present inside the female storage organs and that the lack of sperm in storage is due to failure to transfer sperm rather than spillage or active sperm dumping by females. Sterility of F1QW hybrid males is primarily driven by their inability to transfer sperm during copulation.

A molecular genetic examination of the mating system of pumpkinseed sunfish reveals high pay-offs for specialized sneakers.

PubMed

Rios-Cardenas, Oscar; Webster, Michael S

2008-05-01

Intrasexual variation in reproductive behaviour and morphology are common in nature. Often, such variation appears to result from conditional strategies in which some individuals (e.g. younger males or those in poor condition) adopt a low pay-off phenotype as a 'best of a bad job'. Alternatively, reproductive polymorphisms can be maintained by balancing selection, with male phenotypes having equal fitnesses at equilibrium, but examples from nature are rare. Many species of sunfish (genus Lepomis) are thought to have alternative male reproductive behaviours, but most empirical work has focused on the bluegill sunfish and the mating systems of other sunfish remain poorly understood. We studied a population of pumpkinseed sunfish (Lepomis gibbosus) in upstate New York. Field observations confirm the existence of two male reproductive strategies: 'parentals' were relatively old and large males that maintained nests, and 'sneakers' were relatively young and small males that fertilize eggs by darting into nests of parentals during spawning. The sneaker and parental male strategies appear to be distinct life-history trajectories. Sneaker males represented 39% of the males observed spawning, and sneakers intruded on 43% of all mating attempts. Microsatellite analyses revealed that sneaker males fertilized an average of 15% of the eggs within a nest. This level of paternity by sneaker males appears to be higher than seen in most other fishes, and preliminary analyses suggest that the two male reproductive strategies are maintained as a balanced polymorphism.

Conspicuous female ornamentation and tests of male mate preference in threespine sticklebacks (Gasterosteus aculeatus).

PubMed

Wright, Daniel Shane; Pierotti, Michele E R; Rundle, Howard D; McKinnon, Jeffrey S

2015-01-01

Sexual selection drives the evolution of exaggerated male ornaments in many animal species. Female ornamentation is now acknowledged also to be common but is generally less well understood. One example is the recently documented red female throat coloration in some threespine stickleback (Gasterosteus aculeatus) populations. Although female sticklebacks often exhibit a preference for red male throat coloration, the possibility of sexual selection on female coloration has been little studied. Using sequential and simultaneous mate choice trials, we examined male mate preferences for female throat color, as well as pelvic spine color and standard length, using wild-captured threespine sticklebacks from the Little Campbell River, British Columbia. In a multivariate analysis, we found no evidence for a population-level mate preference in males, suggesting the absence of directional sexual selection on these traits arising from male mate choice. Significant variation was detected among males in their preference functions, but this appeared to arise from differences in their mean responsiveness across mating trials and not from variation in the strength (i.e., slope) of their preference, suggesting the absence of individual-level preferences as well. When presented with conspecific intruder males, male response decreased as intruder red throat coloration increased, suggesting that males can discriminate color and other aspects of phenotype in our experiment and that males may use these traits in intrasexual interactions. The results presented here are the first to explicitly address male preference for female throat color in threespine sticklebacks.

Conspicuous Female Ornamentation and Tests of Male Mate Preference in Threespine Sticklebacks (Gasterosteus aculeatus)

PubMed Central

Wright, Daniel Shane; Pierotti, Michele E. R.; Rundle, Howard D.; McKinnon, Jeffrey S.

2015-01-01

Sexual selection drives the evolution of exaggerated male ornaments in many animal species. Female ornamentation is now acknowledged also to be common but is generally less well understood. One example is the recently documented red female throat coloration in some threespine stickleback (Gasterosteus aculeatus) populations. Although female sticklebacks often exhibit a preference for red male throat coloration, the possibility of sexual selection on female coloration has been little studied. Using sequential and simultaneous mate choice trials, we examined male mate preferences for female throat color, as well as pelvic spine color and standard length, using wild-captured threespine sticklebacks from the Little Campbell River, British Columbia. In a multivariate analysis, we found no evidence for a population-level mate preference in males, suggesting the absence of directional sexual selection on these traits arising from male mate choice. Significant variation was detected among males in their preference functions, but this appeared to arise from differences in their mean responsiveness across mating trials and not from variation in the strength (i.e., slope) of their preference, suggesting the absence of individual-level preferences as well. When presented with conspecific intruder males, male response decreased as intruder red throat coloration increased, suggesting that males can discriminate color and other aspects of phenotype in our experiment and that males may use these traits in intrasexual interactions. The results presented here are the first to explicitly address male preference for female throat color in threespine sticklebacks. PMID:25806520

High HIV Prevalence and Risk Among Male Clients of Female Sex Workers in Hanoi and Ho Chi Minh City, Vietnam.

PubMed

Nadol, Patrick; Hoang, Tran Vu; Le, Linh-Vi; Nguyen, Tuan Anh; Kaldor, John; Law, Matthew

2017-08-01

In Vietnam's concentrated HIV epidemic, female sex workers (FSWs) are at increased risk for acquiring and transmitting HIV, largely through their male clients. A high proportion of males in Vietnam report being clients of FSWs. Studying HIV-related risk factors and prevalence among male clients is important, particularly given the potential for male clients to be a 'bridge' of HIV transmission to the more general population or to sex workers. Time-location sampling was used to identify FSW in Hanoi and Ho Chi Minh City, Vietnam's largest cities, in 2013-2014. Recruited FSWs were asked to refer one male client to the study. Demographic and risk behavior data were collected from FSWs and male clients by administered questionnaires. Biologic specimens collected from male clients were tested for HIV and opiates. Sampling weights, calculated based on the FSWs probability of being selected for enrolment, were applied to prevalence estimates for both FSWs and male clients. Logistic regression models were developed to obtain odds ratios for HIV infection among male clients. A total of 804 male clients were enrolled. Overall, HIV prevalence among male clients was 10.2%; HIV prevalence was 20.7% (95% confidence interval (CI) 15.0-27.9%) among those reporting a history of illegal drug use and 32.4% (95% CI 20.2-47.7%) among those with opioids detected in urine. HIV prevalence among male clients did not differ across 'bridging' categories defined by condom use with FSWs and regular partners over the previous 6 months. HIV among male clients was associated with a reported history of illegal drug use (OR 3.76; 95% CI 1.87-7.56), current opioid use (OR 2.55; 95% CI 1.02-6.36), and being referred by an FSW who self-reported as HIV-positive (OR 5.37; 95% CI 1.46-19.75). Self-reported HIV prevalence among enrolled FSWs was 2.8%. Based on HIV test results of male clients and self-reported status from FSWs, an estimated 12.1% of male client-FSW pairs were sero-discordant. These results indicate high HIV prevalence among male clients of FSWs, particularly among those with a history of drug use. Programs to expand HIV testing, drug-use harm reduction, and HIV treatment for HIV-infected male clients of FSWs should be considered as key interventions for controlling the HIV epidemic in Vietnam.

Do higher dispositions for empathy predispose males toward careers in nursing? A descriptive correlational design.

PubMed

Penprase, Barbara; Oakley, Barbara; Ternes, Reuben; Driscoll, Dana

2015-01-01

The purpose of this research was to understand male nursing students' empathy traits compared with other university students using the systematizing quotient and empathizing quotient questionnaires. Female students have higher empathizing traits than male students. However, when male nursing students were compared with the general population of other male students, they revealed higher empathy traits 3.0 (p < .01) than other males. Empathy plays a significant role in attracting men to a nursing career. Male nurses are not only caring individuals but also have high problem-solving skills in complex environments, demonstrating their strong systemizing characteristics to organize, plan, and implement care. © 2014 Wiley Periodicals, Inc.

The Perils of Being a Male Primary/Junior Teacher: Vulnerability and Accusations of Inappropriate Contact with Students

ERIC Educational Resources Information Center

Parr, Michael; Gosse, Douglas

2011-01-01

There is a perceived shortage of male teachers in education, particularly at the primary/junior (P/J) level where male teachers in Canada account for a dwindling minority. Included among the many factors inhibiting males from becoming P/J teachers are perceptions that males might be unduly vulnerable to false accusations of inappropriate conduct…

A Comparative Perspective of Black College Males on the Achievement Gap: Implications for School Counselors

ERIC Educational Resources Information Center

Bethell, Detra

2013-01-01

The dominant discourse regarding Black males in America is that they are less academically successful than European American males and Black females. Similarly, Black males in the Bahamas are described as less successful than Black Bahamian females. School Counselors are in a unique position to alter the trajectory of success for Black males if…

Need for Physician Education on the Benefits and Risks of Male Circumcision in the United States

ERIC Educational Resources Information Center

Carbery, Baevin; Zhu, Julia; Gust, Deborah A.; Chen, Robert T.; Kretsinger, Katrina; Kilmarx, Peter H.

2012-01-01

Physicians may be called upon to counsel male patients or parents of newborn males regarding their decision to circumcise their newborn sons. The purpose of the present study was to describe physicians who do not understand the benefits and risks associated with male circumcision well enough to counsel parents of newborn male infants and adult…

Consequences of Nosema apis infection for male honey bees and their fertility

PubMed Central

Peng, Yan; Baer-Imhoof, Barbara; Harvey Millar, A.; Baer, Boris

2015-01-01

The queens of eusocial bees, ants and wasps mate only during a very short period early in life and males therefore produce ejaculates consisting of large numbers of high quality sperm. Such extreme selection for high fecundity resulted in males investing minimally into their somatic survival, including their immune system. However, if susceptible males are unable to protect their reproductive tissue from infections, they compromise queen fitness if they transfer pathogens during mating. We used the honey bee Apis mellifera and investigated the course of infection of the sexually transmitted pathogen Nosema apis. We predicted that honey bee males are susceptible but protect their reproductive tissues from infections. We investigated the effects of N. apis infections on the midgut, the accessory glands and the accessory testes and quantified the consequences of infection on male survival and fecundity. We found that N. apis is able to infect males, and as infections progressed, it significantly impacted fertility and survival in older males. Even though we confirm males to be able to minimize N. apis infections of their reproductive tissues, the parasite is present in ejaculates of older males. Consequently N. apis evolved alternative routes to successfully infect ejaculates and get sexually transmitted. PMID:26123530

Consequences of Nosema apis infection for male honey bees and their fertility.

PubMed

Peng, Yan; Baer-Imhoof, Barbara; Millar, A Harvey; Baer, Boris

2015-06-30

The queens of eusocial bees, ants and wasps mate only during a very short period early in life and males therefore produce ejaculates consisting of large numbers of high quality sperm. Such extreme selection for high fecundity resulted in males investing minimally into their somatic survival, including their immune system. However, if susceptible males are unable to protect their reproductive tissue from infections, they compromise queen fitness if they transfer pathogens during mating. We used the honey bee Apis mellifera and investigated the course of infection of the sexually transmitted pathogen Nosema apis. We predicted that honey bee males are susceptible but protect their reproductive tissues from infections. We investigated the effects of N. apis infections on the midgut, the accessory glands and the accessory testes and quantified the consequences of infection on male survival and fecundity. We found that N. apis is able to infect males, and as infections progressed, it significantly impacted fertility and survival in older males. Even though we confirm males to be able to minimize N. apis infections of their reproductive tissues, the parasite is present in ejaculates of older males. Consequently N. apis evolved alternative routes to successfully infect ejaculates and get sexually transmitted.