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Sample records for male group size

  1. Influence of social mixing and group size on skin lesions and mounting in organic entire male pigs.

    PubMed

    Thomsen, R; Edwards, S A; Rousing, T; Labouriau, R; Sørensen, J T

    2016-07-01

    Alternatives to surgical castration are needed, due to stress and pain caused by castration of male pigs. One alternative is production of entire male pigs. However, changed behaviour of entire males compared with castrated males might adversely affect the welfare of entire males and changes in management procedures and production system might be needed. Elements from the organic pig production system might be beneficial in this aspect. The aim of this article is to investigate the effect of grouping strategy including social mixing and group size on levels of mounting behaviour and skin lesions, hypothesising that procedures that disrupt the social stability (e.g. regrouping) will have a larger negative effect in small groups compared with large groups. Approximately 1600 organic entire male pigs of the breed (Landrace×Yorkshire)×Duroc were reared in parallel in five organic herds, distributed across four batches in a 2×2 factorial design in order to test the influence of social mixing (presence or absence of social mixing at relocation) and group size (15 and 30 animals). Animals were able to socialise with piglets from other litters during the lactation period, and were all mixed across litters at weaning. A second mixing occurred at insertion to fattening pens for pigs being regrouped. Counting of skin lesions (1348 or 1124 pigs) and registration of mounting behaviour (1434 or 1258 pigs) were done on two occasions during the experimental period. No interactive effects were found between social mixing and group size on either skin lesions or mounting frequency. Herd differences were found for both mounting frequency and number of skin lesions. No association between skin lesions and mounting were revealed. Social mixing and group size were shown as interacting effects with herds on mounting frequency (P<0.0001), but with no consistent pattern across all herds. In addition, no effect of social mixing was found on mean number of skin lesions, but more lesions

  2. 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. PMID:27420790

  3. Experimentally increased badge size increases male competition and reduces male parental care in the collared flycatcher

    PubMed Central

    Qvarnstroöm, A.

    1997-01-01

    Experimental enlargement of sexually selected traits that are energetically cheap to produce is expected to reveal costs resulting from increased risk of predation or social competition. Given a trade-off between sexually selected traits and life history traits such costs may be expected to affect not only the males themselves but also their offspring. In this study I manipulated the size of the forehead patch, a sexually selected trait that functions as a badge of status in male collared flycatchersFicedula albicollis). First, I found that a male's likelihood to establish a breeding territory with respect to his original badge size was affected by the treatment such that old males (older than or equal to two years) with relatively small original badges enjoyed an increased likelihood of establishing a breeding territory while young males (yearlings) suffered a reduced likelihood of establishment when their badges were enlarged as compared to unchanged. Second, young males with enlarged badges that were able to establish a territory fed their nestlings less in relation to their females compared to the control males. However, the females adjusted their parental effort to such an extent that no significant differences were observed in total feeding rate nor in reproductive success between the two groups of males. These results suggest that experimentally enlarged badge size in the collared flycatcher may result in increased male competition and that males have to trade their effort spent in male contest against their parental effort.

  4. Male Reference Group Identity Dependence: A Theory of Male Identity.

    ERIC Educational Resources Information Center

    Wade, Jay C.

    1998-01-01

    Presents a theory of male identity developed to address the question of why men vary in their masculinity ideology and in their conformity to standards of masculinity. An overview of relevant masculinity research, theoretical foundations for the construct of reference group identity dependence, theoretical postulates, associated behavioral, and…

  5. 36 CFR 13.905 - Group size.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Group size. 13.905 Section 13... § 13.905 Group size. (a) The following are prohibited: (1) Group sizes exceeding 12 individuals on the east side of the park outside the Frontcountry Developed Area as defined by this subpart. (2)...

  6. 36 CFR 13.905 - Group size.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Group size. 13.905 Section 13... § 13.905 Group size. (a) The following are prohibited: (1) Group sizes exceeding 12 individuals on the east side of the park outside the Frontcountry Developed Area as defined by this subpart. (2)...

  7. Scaling in animal group-size distributions

    PubMed Central

    Bonabeau, Eric; Dagorn, Laurent; Fréon, Pierre

    1999-01-01

    An elementary model of animal aggregation is presented. The group-size distributions resulting from this model are truncated power laws. The predictions of the model are found to be consistent with data that describe the group-size distributions of tuna fish, sardinellas, and African buffaloes. PMID:10200286

  8. Fitness consequences of artificial selection on relative male genital size.

    PubMed

    Booksmythe, Isobel; Head, Megan L; Keogh, J Scott; Jennions, Michael D

    2016-01-01

    Male genitalia often show remarkable differences among related species in size, shape and complexity. Across poeciliid fishes, the elongated fin (gonopodium) that males use to inseminate females ranges from 18 to 53% of body length. Relative genital size therefore varies greatly among species. In contrast, there is often tight within-species allometric scaling, which suggests strong selection against genital-body size combinations that deviate from a species' natural line of allometry. We tested this constraint by artificially selecting on the allometric intercept, creating lines of males with relatively longer or shorter gonopodia than occur naturally for a given body size in mosquitofish, Gambusia holbrooki. We show that relative genital length is heritable and diverged 7.6-8.9% between our up-selected and down-selected lines, with correlated changes in body shape. However, deviation from the natural line of allometry does not affect male success in assays of attractiveness, swimming performance and, crucially, reproductive success (paternity). PMID:27188478

  9. Roosevelt elk density and social segregation: Foraging behavior and females avoiding larger groups of males

    USGS Publications Warehouse

    Weckerly, F.; McFarland, K.; Ricca, M.; Meyer, K.

    2004-01-01

    Intersexual social segregation at small spatial scales is prevalent in ruminants that are sexually dimorphic in body size. Explaining social segregation, however, from hypotheses of how intersexual size differences affects the foraging process of males and females has had mixed results. We studied whether body size influences on forage behavior, intersexual social incompatibility or both might influence social segregation in a population of Roosevelt elk (Cervus elaphus roosevelt) that declined 40% over 5 y. Most males and females in the population occurred in the same forage patches, meadows, but occupied different parts of meadows and most groups were overwhelming comprised of one sex. The extent of segregation varied slightly with changing elk density. Cropping rate, our surrogate of forage ingestion, of males in mixed-sex groups differed from males in male-only groups at high, but not low, elk density. In a prior study of intersexual social interactions it was shown that females avoided groups containing ???6 males. Therefore, we predicted that females should avoid parts of meadows where groups of males ???6 were prevalent. Across the 5 y of study this prediction held because ???5% of all females were found in parts of meadows where median aggregation sizes of males were ???6. Social segregation was coupled to body size influences on forage ingestion at high density and social incompatibility was coupled to social segregation regardless of elk density.

  10. Demographic correlates of sexual size dimorphism and male genital size in the lice Philopterus coarctatus.

    PubMed

    Tryjanowski, Piotr; Adamski, Zbigniew; Dylewska, Magdalena; Bulkai, Lajos; Rózsa, Lajos

    2009-10-01

    Sexual selection is an influential agent of evolution, often shaping the sex ratio, sexual size dimorphism (SSD), and genital size in animals. To explore its effects in ectoparasites, we quantified SSD and male genital size in relation to intensity and sex ratio across subpopulations of Philopterus coarctatus, a philopterid louse of the great grey shrike. SSD was calculated separately for the width and length of the head and abdomen. Presuming that sexual selection affects the evolution of avian lice, we would expect that infestation intensities should covary with sex ratio, relative male size, and relative male genital size, either positively or negatively depending upon presumptions. Contrary to former studies, there was a weak negative relationship between infestation intensity and sex ratio. The relative width of male abdomens exhibited a highly significant negative interaction with the intensity of infestations. In contrast, sex ratio did not predict any of the dimorphism measures. Similarly, male genital size did not covary with the intensity of infestations or sex ratios. These findings may indicate that intensity covaries positively with levels of inbreeding in this species, suggesting that more-inbred subpopulations, wasting less energy for sexual rivalry, can multiply more intensively. Thus, small subpopulations have more frequent males which also possess larger abdomens. Alternatively, however, the same pattern may also arise due to male-biased starvation in overcrowded habitats; thus, males are rarer and have smaller abdomens in larger infrapopulations. PMID:19320542

  11. 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. PMID:25598523

  12. Fitness consequences of artificial selection on relative male genital size

    PubMed Central

    Booksmythe, Isobel; Head, Megan L.; Keogh, J. Scott; Jennions, Michael D.

    2016-01-01

    Male genitalia often show remarkable differences among related species in size, shape and complexity. Across poeciliid fishes, the elongated fin (gonopodium) that males use to inseminate females ranges from 18 to 53% of body length. Relative genital size therefore varies greatly among species. In contrast, there is often tight within-species allometric scaling, which suggests strong selection against genital–body size combinations that deviate from a species' natural line of allometry. We tested this constraint by artificially selecting on the allometric intercept, creating lines of males with relatively longer or shorter gonopodia than occur naturally for a given body size in mosquitofish, Gambusia holbrooki. We show that relative genital length is heritable and diverged 7.6–8.9% between our up-selected and down-selected lines, with correlated changes in body shape. However, deviation from the natural line of allometry does not affect male success in assays of attractiveness, swimming performance and, crucially, reproductive success (paternity). PMID:27188478

  13. The macroevolution of size and complexity in insect male genitalia

    PubMed Central

    Rudoy, Andrey

    2016-01-01

    The evolution of insect male genitalia has received much attention, but there is still a lack of data on the macroevolutionary origin of its extraordinary variation. We used a calibrated molecular phylogeny of 71 of the 150 known species of the beetle genus Limnebius to study the evolution of the size and complexity of the male genitalia in its two subgenera, Bilimneus, with small species with simple genitalia, and Limnebius s.str., with a much larger variation in size and complexity. We reconstructed ancestral values of complexity (perimeter and fractal dimension of the aedeagus) and genital and body size with Bayesian methods. Complexity evolved more in agreement with a Brownian model, although with evidence of weak directional selection to a decrease or increase in complexity in the two subgenera respectively, as measured with an excess of branches with negative or positive change. On the contrary, aedeagus size, the variable with the highest rates of evolution, had a lower phylogenetic signal, without significant differences between the two subgenera in the average change of the individual branches of the tree. Aedeagus size also had a lower correlation with time and no evidence of directional selection. Rather than to directional selection, it thus seems that the higher diversity of the male genitalia in Limnebius s.str. is mostly due to the larger variance of the phenotypic change in the individual branches of the tree for all measured variables. PMID:27114865

  14. The macroevolution of size and complexity in insect male genitalia.

    PubMed

    Rudoy, Andrey; Ribera, Ignacio

    2016-01-01

    The evolution of insect male genitalia has received much attention, but there is still a lack of data on the macroevolutionary origin of its extraordinary variation. We used a calibrated molecular phylogeny of 71 of the 150 known species of the beetle genus Limnebius to study the evolution of the size and complexity of the male genitalia in its two subgenera, Bilimneus, with small species with simple genitalia, and Limnebius s.str., with a much larger variation in size and complexity. We reconstructed ancestral values of complexity (perimeter and fractal dimension of the aedeagus) and genital and body size with Bayesian methods. Complexity evolved more in agreement with a Brownian model, although with evidence of weak directional selection to a decrease or increase in complexity in the two subgenera respectively, as measured with an excess of branches with negative or positive change. On the contrary, aedeagus size, the variable with the highest rates of evolution, had a lower phylogenetic signal, without significant differences between the two subgenera in the average change of the individual branches of the tree. Aedeagus size also had a lower correlation with time and no evidence of directional selection. Rather than to directional selection, it thus seems that the higher diversity of the male genitalia in Limnebius s.str. is mostly due to the larger variance of the phenotypic change in the individual branches of the tree for all measured variables. PMID:27114865

  15. Male reproductive success increases with alliance size in Indo-Pacific bottlenose dolphins (Tursiops aduncus).

    PubMed

    Wiszniewski, Joanna; Corrigan, Shannon; Beheregaray, Luciano B; Möller, Luciana M

    2012-03-01

    1. Determining the extent of variation in male mating strategies and reproductive success is necessary to understand the fitness benefits of social and cooperative behaviour. 2. This study assesses the reproductive success of male Indo-Pacific bottlenose dolphins in a small embayment population where different behavioural strategies of males have previously been identified. Parentage for 44 sampled calves was examined using 23 microsatellite loci and one mitochondrial DNA marker. Our candidate parent pool of 70 males and 64 females contained individuals sampled from both the embayment and adjacent coastal populations. 3. A moderate level of polygyny was detected in our sample. We assigned paternity of 23 calves to 12 males at the strict 95% confidence level and an additional nine calves to two males at the 80% confidence level. The majority (92%) of successful males were identified as residents to the embayment, and 46% of offspring were located within the same social group or community as their father. 4. Our results suggest that the size of alliances was the best predictor of reproductive success for males in this population, while the strength of association among allied males, alliance stability and male ranging patterns had little influence. In line with predictions for male alliances formed between unrelated individuals, we found that reproductive skew within alliances was not large. 5. Together, our genetic and behavioural analyses demonstrate that alliance formation between male dolphins is a successful strategy to enhance reproductive output. PMID:21981240

  16. The effects of meal size and body size on individuals' impressions of males and females.

    PubMed

    Martins, Yolanda; Pliner, Patricia; Lee, Corrie

    2004-05-01

    Male and female participants provided impression ratings for either a normal-weight or overweight male or female target, who was portrayed as eating either small or large meals. Males rated normal-weight targets as more physically attractive than overweight targets, whereas ratings of physical attractiveness were unaffected by the body size manipulation among female participants. In addition, among male targets, the overweight large eater was rated the least socially attractive. For female targets, males rated the normal-weight large eater as the most socially attractive, whereas females rated the normal-weight small eater as the most socially attractive. Results are discussed in terms of how body and meal sizes interact to affect impressions of others. PMID:15093782

  17. Density-dependent effects on group size are sex-specific in a gregarious ungulate.

    PubMed

    Vander Wal, Eric; van Beest, Floris M; Brook, Ryan K

    2013-01-01

    Density dependence can have marked effects on social behaviors such as group size. We tested whether changes in population density of a large herbivore (elk, Cervus canadensis) affected sex-specific group size and whether the response was density- or frequency-dependent. We quantified the probability and strength of changes in group sizes and dispersion as population density changed for each sex. We used group size data from a population of elk in Manitoba, Canada, that was experimentally reduced from 1.20 to 0.67 elk/km(2) between 2002 and 2009. Our results indicated that functional responses of group size to population density are sex-specific. Females showed a positive density-dependent response in group size at population densities ≥0.70 elk/km(2) and we found evidence for a minimum group size at population density ≤0.70 elk/km(2). Changes in male group size were also density-dependent; however, the strength of the relationship was lower than for females. Density dependence in male group size was predominantly a result of fusion of solitary males into larger groups, rather than fusion among existing groups. Our study revealed that density affects group size of a large herbivore differently between males and females, which has important implications for the benefits e.g., alleviating predation risk, and costs of social behaviors e.g., competition for resources and mates, and intra-specific pathogen transmission. PMID:23326502

  18. Density-Dependent Effects on Group Size Are Sex-Specific in a Gregarious Ungulate

    PubMed Central

    Vander Wal, Eric; van Beest, Floris M.; Brook, Ryan K.

    2013-01-01

    Density dependence can have marked effects on social behaviors such as group size. We tested whether changes in population density of a large herbivore (elk, Cervus canadensis) affected sex-specific group size and whether the response was density- or frequency-dependent. We quantified the probability and strength of changes in group sizes and dispersion as population density changed for each sex. We used group size data from a population of elk in Manitoba, Canada, that was experimentally reduced from 1.20 to 0.67 elk/km2 between 2002 and 2009. Our results indicated that functional responses of group size to population density are sex-specific. Females showed a positive density-dependent response in group size at population densities ≥0.70 elk/km2 and we found evidence for a minimum group size at population density ≤0.70 elk/km2. Changes in male group size were also density-dependent; however, the strength of the relationship was lower than for females. Density dependence in male group size was predominantly a result of fusion of solitary males into larger groups, rather than fusion among existing groups. Our study revealed that density affects group size of a large herbivore differently between males and females, which has important implications for the benefits e.g., alleviating predation risk, and costs of social behaviors e.g., competition for resources and mates, and intra-specific pathogen transmission. PMID:23326502

  19. Portion size and intended consumption. Evidence for a pre-consumption portion size effect in males?

    PubMed

    Robinson, Eric; te Raa, Wesselien; Hardman, Charlotte A

    2015-08-01

    Larger portions increase energy intake (the 'portion size effect'); however, the mechanisms behind this effect are unclear. Although pre-meal intentions are thought to be an important determinant of energy intake, little research has examined how much of a meal individuals intend to eat when served standard versus larger portion sizes. Three studies examined the effect of manipulating portion size on intended food consumption. In Studies 1 (spaghetti bolognese) and 2 (curry and rice) male participants were shown an image of either a standard or a larger meal and indicated how much of the meal they intended to consume. In Study 3 male and female participants were served either a standard or a larger portion of ice cream for dessert, they indicated how much they intended to consume and then ate as much of the ice cream as they desired. Regardless of being shown standard or large portion sizes, in Studies 1 and 2 participants reported that they intended to eat the majority of the meal, equating to a large difference in intended energy consumption between portion size conditions (a 'pre-consumption portion size effect'). This finding was replicated in male participants in Study 3, although females intended to eat a smaller proportion of the larger portion of ice cream, compared to the standard portion. Both male and female participants tended to eat in accordance with their pre-meal intentions and a portion size effect on actual consumption was subsequently observed in males, but not in females. The portion size effect may be observed when measuring pre-meal intended consumption in males. PMID:25865660

  20. Size perception is less context-sensitive in males.

    PubMed

    Phillips, William A; Chapman, Katie L S; Berry, P Daniel

    2004-01-01

    Context sensitivity of size perception has previously been used to study individual differences related to the distinction between local, analytic, or field-independent and global, holistic, or field-dependent perceptual styles. For example, it has been used in several recent studies of autistic spectrum disorders, which may involve an excessive bias toward local processing. Autism is much more common in males, and there is evidence that this may be in part because males in general tend to be less context-sensitive than females, and thus are more affected by conditions that further reduce context sensitivity. There is also evidence that a bias to local processing is more common in professions that require attention to detail. Context sensitivity of size perception was therefore studied as a function of sex and academic discipline in sixty-four university staff and students by a simple, sensitive, and specific psychophysical measure based on the Ebbinghaus illusion. The results show that in this task males are on average less context-sensitive than females, that the overlap is large, and that subjects with very high or very low context sensitivity tend to have the sex and profession predicted by the above hypotheses. PMID:15035330

  1. Genetic aspects of communication during male-male competition in the Madagascar hissing cockroach: honest signalling of size.

    PubMed

    Clark, D C; Moore, A J

    1995-08-01

    Male Madagascar hissing cockroaches, Gromphadorhina portentosa, engage in agonistic contests with other males and produce audible sounds or 'hisses' during these interactions. Hisses are used to maintain, rather than to establish, social relationships among males. The agonistic hisses of males are variable and could be used as signals to communicate size or competitive ability of an individual. In this study we examined how size influences male-male competition, as well as the genetic variation and covariation of male body size and components of the agonistic hiss. We found that male size affected the outcome of agonistic interactions between pairs of males: a male that dominated in a pair was significantly larger than the male that was subordinate. However, we found no differences in the hisses produced by dominant and subordinate males after controlling for male weight. We estimated heritabilities, evolvability and genetic correlations for male size and characteristics of the hiss from a full-sib analysis of brothers. The patterns of heritabilities and evolvabilities were very similar. The heritabilities of both male weight and duration of the hiss were significantly greater than zero. There was a significant positive genetic correlation between duration of the agonistic hiss and male weight, and a significant negative genetic correlation between hiss duration and the beginning dominant frequency. There was also a positive phenotypic correlation and a negative environmental correlation between male weight and hiss duration. Thus, hiss duration can signal the present influence of the environment on male size, whereas information from hiss duration and beginning dominant frequency can signal the male's ability to transmit genetic influence for size.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7558888

  2. Sexual selection on male size drives the evolution of male-biased sexual size dimorphism via the prolongation of male development.

    PubMed

    Rohner, Patrick T; Blanckenhorn, Wolf U; Puniamoorthy, Nalini

    2016-06-01

    Sexual size dimorphism (SSD) arises when the net effects of natural and sexual selection on body size differ between the sexes. Quantitative SSD variation between taxa is common, but directional intraspecific SSD reversals are rare. We combined micro- and macroevolutionary approaches to study geographic SSD variation in closely related black scavenger flies. Common garden experiments revealed stark intra- and interspecific variation: Sepsis biflexuosa is monomorphic across the Holarctic, while S. cynipsea (only in Europe) consistently exhibits female-biased SSD. Interestingly, S. neocynipsea displays contrasting SSD in Europe (females larger) and North America (males larger), a pattern opposite to the geographic reversal in SSD of S. punctum documented in a previous study. In accordance with the differential equilibrium model for the evolution of SSD, the intensity of sexual selection on male size varied between continents (weaker in Europe), whereas fecundity selection on female body size did not. Subsequent comparative analyses of 49 taxa documented at least six independent origins of male-biased SSD in Sepsidae, which is likely caused by sexual selection on male size and mediated by bimaturism. Therefore, reversals in SSD and the associated changes in larval development might be much more common and rapid and less constrained than currently assumed. PMID:27168489

  3. Group Work Practice with Transgendered Male to Female Sex Workers.

    ERIC Educational Resources Information Center

    Klein, Rebecca

    1999-01-01

    Examines group work with transgendered male-to-female adolescents who engage in sex work. Provides an overview of the role that sex work plays in the lives of some transgendered youth, using case examples, and offers guidance for those utilizing group work approaches with transgendered adolescents. Discusses homelessness and institutionalization,…

  4. Group structure predicts variation in proximity relationships between male-female and male-infant pairs of mountain gorillas (Gorilla beringei beringei).

    PubMed

    Rosenbaum, S; Maldonado-Chaparro, A A; Stoinski, T S

    2016-01-01

    Relationships between conspecifics are influenced by both ecological factors and the social organization they live in. Systematic variation of both--consistent with predictions derived from socioecology models--is well documented, but there is considerable variation within species and populations that is poorly understood. The mountain gorilla (Gorilla beringei) is unusual because, despite possessing morphology associated with male contest competition (e.g., extreme sexual dimorphism), they are regularly observed in both single-male and multimale groups. Both male-female and male-infant bonds are strong because males provide protection against infanticide and/or predation. Risk of these threats varies with social structure, which may influence the strength of social relationships among group members (including females and offspring, if females with lower infant mortality risk are less protective of infants). Here, we investigate the relationship between group structure and the strength of proximity relationships between males and females, males and infants, and females and offspring. Data come from 10 social groups containing 1-7 adult males, monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center in Volcanoes National Park, Rwanda. After controlling for group size and infant age, association strength was similar for male-female pairs across group types with both dominant and nondominant males, but male-infant relationships were strongest in single-male groups where paternity certainty was high and animals had fewer social partners to choose from. The male:female and male:infant ratios better predicted both male-female and male-infant associations than the absolute number of males, females, or infants did. The fewer the number of males per female or infant, the more both pair types associated. Dominant males in groups containing fewer males had higher eigenvector centrality (a measure of importance in a social network) than dominant males in groups

  5. Male-immature relationships in multi-male groups of mountain gorillas (Gorilla beringei beringei).

    PubMed

    Rosenbaum, S; Silk, J B; Stoinski, T S

    2011-04-01

    We examined the pattern and possible functions of social interactions between adult males and immatures in three free-ranging, multi-male groups of mountain gorillas (Gorilla beringei beringei). Previous studies conducted during the 1970s when groups contained one to three adult males concluded that male-immature relationships were likely to be a form of low-cost paternal investment [Stewart, Mountain gorillas: three decades of research at Karisoke. Cambridge, UK: Cambridge University Press, 2001]. We evaluated whether this hypothesis still held in groups containing six to nine adult males, or if male-immature relationships might serve other functions (e.g. mating effort, kin selection, or alliance building). Overall, we found that immatures spent the most time near, and interacted most with, the alpha silverback. These behaviors peaked during the period when infants were still quite vulnerable but increasing their independence from their mothers. Such findings suggest that parenting effort remains the primary function of male-immature relationships; however, there is some evidence for the mating effort hypothesis as well. PMID:21328594

  6. A model for group-size-dependent behaviour decisions in insects using an oscillator network.

    PubMed

    Funato, Tetsuro; Nara, Masahito; Kurabayashi, Daisuke; Ashikaga, Masatoshi; Aonuma, Hitoshi

    2011-07-15

    Aggressive behaviour within pairs of male crickets leads to the establishment of a dominance hierarchy. Defeated males avoid their victorious adversaries for several hours before regaining aggressiveness. However, the defeated male does not regain aggressiveness if repeated fighting occurs. Loss of individual aggressiveness is limited by group size, which constrains the number of crickets fighting at any given time. Thus, group aggressive behaviour is modulated by an environmental factor, group size, which is ultimately determined by individual actions, i.e. fighting between two individuals. We developed a robot model to elucidate the mechanism of group-size-dependent behaviour alternation in crickets. The behaviour of individual robots was evaluated experimentally with mobile robots and the group behaviour of the robots was evaluated by computer simulation. We demonstrated that the group-size-dependent strategy in crickets could be generated by local interactions between robots, where the behaviour was governed by an oscillator and memory of the outcome of previous fights. PMID:21697435

  7. Prediction and measurement of frame size in young adult males.

    PubMed

    Peters, D M; Eston, R

    1993-02-01

    The assessment of frame size is a problematic and ambiguous area. The purpose of this study was to assess the level of agreement between various techniques of assessing frame size in a group of 27 healthy and active men aged 18-24 years, and also to assess which anthropometric variables were best associated with a measure of actual frame size (AFS) which is proposed in this study. Actual frame size was measured by the summation of a series of bone breadths, lengths and depths on a sub-sample of 17 men. The results of the study revealed substantial discordance between methods of assessing frame size. The variables which correlated most highly with AFS (P < 0.01) were body mass, ankle breadth, hand length and chest breadth, respectively. These variables were also positively correlated (P < 0.01) with fat-free mass (FFM), with no significant correlation with fat mass in either case. Of the various documented methods used to assess frame size, the 'HAT' technique, which incorporates biacromial and bitrochanteric breadths, was more highly correlated with AFS than both elbow breadth (currently used in height-weight insurance tables) and the height/wrist circumference index. The latter measure was not highly correlated with AFS, body mass and FFM in this study. It was concluded that ankle breadth and hand length may be better predictors of frame size in young men than other bone dimensions. In addition, the results of this preliminary investigation have substantiated the potential viability of an AFS model. Future research using this technique is recommended to determine true indicators of frame size in a larger and more heterogeneous population. PMID:8450591

  8. 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

  9. 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

  10. Limited indirect fitness benefits of male group membership in a lekking species.

    PubMed

    Lebigre, Christophe; Alatalo, Rauno V; Soulsbury, Carl D; Höglund, Jacob; Siitari, Heli

    2014-11-01

    In group living species, individuals may gain the indirect fitness benefits characterizing kin selection when groups contain close relatives. However, tests of kin selection have primarily focused on cooperatively breeding and eusocial species, whereas its importance in other forms of group living remains to be fully understood. Lekking is a form of grouping where males display on small aggregated territories, which females then visit to mate. As females prefer larger aggregations, territorial males might gain indirect fitness benefits if their presence increases the fitness of close relatives. Previous studies have tested specific predictions of kin selection models using measures such as group-level relatedness. However, a full understanding of the contribution of kin selection in the evolution of group living requires estimating individuals' indirect fitness benefits across multiple sites and years. Using behavioural and genetic data from the black grouse (Tetrao tetrix), we show that the indirect fitness benefits of group membership were very small because newcomers joined leks containing few close relatives who had limited mating success. Males' indirect fitness benefits were higher in yearlings during increasing population density but marginally changed the variation in male mating success. Kin selection acting through increasing group size is therefore unlikely to contribute substantially to the evolution and maintenance of lekking in this black grouse population. PMID:25263625

  11. Optimal group size in a highly social mammal.

    PubMed

    Markham, A Catherine; Gesquiere, Laurence R; Alberts, Susan C; Altmann, Jeanne

    2015-12-01

    Group size is an important trait of social animals, affecting how individuals allocate time and use space, and influencing both an individual's fitness and the collective, cooperative behaviors of the group as a whole. Here we tested predictions motivated by the ecological constraints model of group size, examining the effects of group size on ranging patterns and adult female glucocorticoid (stress hormone) concentrations in five social groups of wild baboons (Papio cynocephalus) over an 11-y period. Strikingly, we found evidence that intermediate-sized groups have energetically optimal space-use strategies; both large and small groups experience ranging disadvantages, in contrast to the commonly reported positive linear relationship between group size and home range area and daily travel distance, which depict a disadvantage only in large groups. Specifically, we observed a U-shaped relationship between group size and home range area, average daily distance traveled, evenness of space use within the home range, and glucocorticoid concentrations. We propose that a likely explanation for these U-shaped patterns is that large, socially dominant groups are constrained by within-group competition, whereas small, socially subordinate groups are constrained by between-group competition and predation pressures. Overall, our results provide testable hypotheses for evaluating group-size constraints in other group-living species, in which the costs of intra- and intergroup competition vary as a function of group size. PMID:26504236

  12. Optimal group size in a highly social mammal

    PubMed Central

    Markham, A. Catherine; Gesquiere, Laurence R.; Alberts, Susan C.; Altmann, Jeanne

    2015-01-01

    Group size is an important trait of social animals, affecting how individuals allocate time and use space, and influencing both an individual’s fitness and the collective, cooperative behaviors of the group as a whole. Here we tested predictions motivated by the ecological constraints model of group size, examining the effects of group size on ranging patterns and adult female glucocorticoid (stress hormone) concentrations in five social groups of wild baboons (Papio cynocephalus) over an 11-y period. Strikingly, we found evidence that intermediate-sized groups have energetically optimal space-use strategies; both large and small groups experience ranging disadvantages, in contrast to the commonly reported positive linear relationship between group size and home range area and daily travel distance, which depict a disadvantage only in large groups. Specifically, we observed a U-shaped relationship between group size and home range area, average daily distance traveled, evenness of space use within the home range, and glucocorticoid concentrations. We propose that a likely explanation for these U-shaped patterns is that large, socially dominant groups are constrained by within-group competition, whereas small, socially subordinate groups are constrained by between-group competition and predation pressures. Overall, our results provide testable hypotheses for evaluating group-size constraints in other group-living species, in which the costs of intra- and intergroup competition vary as a function of group size. PMID:26504236

  13. Male lifetime mating success in relation to body size in Diabrotica barberi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Body size is often an important component of male lifetime mating success in insects, especially when males are capable of mating several times over their lifespan. We paired either a large or small male northern corn rootworm with a female of random size and noted copulation success. We observed co...

  14. Brain size affects female but not male survival under predation threat

    PubMed Central

    Kotrschal, Alexander; Buechel, Séverine D; Zala, Sarah M; Corral-Lopez, Alberto; Penn, Dustin J; Kolm, Niclas; Sorci, Gabriele

    2015-01-01

    There is remarkable diversity in brain size among vertebrates, but surprisingly little is known about how ecological species interactions impact the evolution of brain size. Using guppies, artificially selected for large and small brains, we determined how brain size affects survival under predation threat in a naturalistic environment. We cohoused mixed groups of small- and large-brained individuals in six semi-natural streams with their natural predator, the pike cichlid, and monitored survival in weekly censuses over 5 months. We found that large-brained females had 13.5% higher survival compared to small-brained females, whereas the brain size had no discernible effect on male survival. We suggest that large-brained females have a cognitive advantage that allows them to better evade predation, whereas large-brained males are more colourful, which may counteract any potential benefits of brain size. Our study provides the first experimental evidence that trophic interactions can affect the evolution of brain size. PMID:25960088

  15. Brain size affects female but not male survival under predation threat.

    PubMed

    Kotrschal, Alexander; Buechel, Séverine D; Zala, Sarah M; Corral-Lopez, Alberto; Penn, Dustin J; Kolm, Niclas

    2015-07-01

    There is remarkable diversity in brain size among vertebrates, but surprisingly little is known about how ecological species interactions impact the evolution of brain size. Using guppies, artificially selected for large and small brains, we determined how brain size affects survival under predation threat in a naturalistic environment. We cohoused mixed groups of small- and large-brained individuals in six semi-natural streams with their natural predator, the pike cichlid, and monitored survival in weekly censuses over 5 months. We found that large-brained females had 13.5% higher survival compared to small-brained females, whereas the brain size had no discernible effect on male survival. We suggest that large-brained females have a cognitive advantage that allows them to better evade predation, whereas large-brained males are more colourful, which may counteract any potential benefits of brain size. Our study provides the first experimental evidence that trophic interactions can affect the evolution of brain size. PMID:25960088

  16. Size-dependent response to conspecific mating calls by male crickets.

    PubMed Central

    Kiflawi, M; Gray, D A

    2000-01-01

    Male sexual displays provide females with information that is crucial to their reproductive decisions. That same information is available to eavesdroppers, with potential consequences for both signaller and receiver. We present empirical evidence for size-dependent responses to intersexual communication by conspecific rivals. Acoustic features of a male house cricket's (Acheta domesticus) mating call are positively associated with its size, with females preferring the calls of larger males. In order to investigate whether conspecific males make use of the information content of mating calls, we examined their phonotactic responses to call recordings that differ in attractiveness to females. Males of all sizes exhibited positive phonotaxis, with smaller males showing a clear preference for female-preferred calls. Smaller males were also less likely to seek contact with the speaker playing their chosen call. We discuss possible explanations for this size-dependent male behaviour. PMID:11413627

  17. Size-dependent selective mechanisms on males and females and the evolution of sexual size dimorphism in frogs.

    PubMed

    Nali, Renato C; Zamudio, Kelly R; Haddad, Célio F B; Prado, Cynthia P A

    2014-12-01

    Sexual size dimorphism (SSD) varies in animals from male biased to female biased. The evolution of SSD is potentially influenced by a number of factors, such as territoriality, fecundity, and temporal breeding patterns (explosive vs. prolonged). In general, frogs show female-biased SSD with broad variance among species. Using comparative methods, we examine how different selective forces affect male and female sizes, and we test hypotheses about size-dependent mechanisms shaping SSD in frogs. Male size was weakly associated with SSD in all size classes, and we found no significant association among SSD, male size, temporal breeding pattern, and male territoriality. In contrast, female size best explained SSD variation across all size classes but especially for small-bodied species. We found a stronger evolutionary association between female body size and fecundity, and this fecundity advantage was highest in explosively breeding species. Our data indicate that the fecundity advantage associated with female body size may not be linear, such that intermediate and large females benefit less with body size increases. Therefore, size-dependent selection in females associated with fecundity and breeding patterns is an important mechanism driving SSD evolution in frogs. Our study underscores the fact that lineage-specific ecology and behavior should be incorporated in comparative analyses of animal SSD. PMID:25438173

  18. 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. PMID:26658421

  19. Variability in group size and the evolution of collective action.

    PubMed

    Peña, Jorge; Nöldeke, Georg

    2016-01-21

    Models of the evolution of collective action typically assume that interactions occur in groups of identical size. In contrast, social interactions between animals occur in groups of widely dispersed size. This paper models collective action problems as two-strategy multiplayer games and studies the effect of variability in group size on the evolution of cooperative behavior under the replicator dynamics. The analysis identifies elementary conditions on the payoff structure of the game implying that the evolution of cooperative behavior is promoted or inhibited when the group size experienced by a focal player is more or less variable. Similar but more stringent conditions are applicable when the confounding effect of size-biased sampling, which causes the group-size distribution experienced by a focal player to differ from the statistical distribution of group sizes, is taken into account. PMID:26551151

  20. [Efficacy of group psychotherapy for homosexual aging males].

    PubMed

    Gagliesi, Pablo

    2002-12-01

    The aim of this research is try to expose and to debate the groupal psychotherapy experience of homosexual males older than 65 years, in Buenos Aires. The starting point for this work is based on that homogeneous groups are effective in some contexts, what is demonstrated by the results at the beginning and at the end of the samples of the BSI and SAS, although this data are not, like it was supposed, commonly linked with the selected biographical antecedents (abuse of power, bereavements during the last military dictatorships, bereavements as result of the AIDS epidemic and the difficulties in the economic survival). PMID:12478313

  1. Bigger Is Not Always Better: Females Prefer Males of Mean Body Size in Philautus odontotarsus.

    PubMed

    Zhu, Bicheng; Wang, Jichao; Zhao, Longhui; Sun, Zhixin; Brauth, Steven E; Tang, Yezhong; Cui, Jianguo

    2016-01-01

    Most species are believed to evolve larger body sizes over evolutionary time. Previous studies have suggested that sexual selection, through male-male competition and female choice, favors larger males. However, there is little evidence of selection against large size. The female serrate-legged small treefrogs (Philautus odontotarsus) must carry passive males from leks to breeding grounds over relatively long distances after amplexus to find a suitable place to lay eggs. The costs of large male size may therefore decrease mating success due to reduced agility and/or higher energy requirements. Thus, we hypothesized that selection would not favor larger males in P. odontotarsus. Females can assess male body size on the basis of the dominant frequency of male calls in frogs. To assess female P. odontotarsus preferences for a potential mate's body size, male calls of high, average and low dominant frequency were played back to the females in phonotaxis experiments. Results showed that most females prefer the advertisement call with average dominant frequency. In addition, we compared the body mass distribution of amplectant males with that of single males in nature. The body masses of amplectant males are more narrowly distributed in the intermediate range than that of single males. The phonotaxis results and the data of actual female preferences in the field show that females strongly prefer potential mates of mean body sizes, consistent with the view that, in this species at least, larger males are not always perceived as better by females. In the present study, P. odontotarsus provides an example of an amphibian species in which large size does not have an advantage in mating success for males. Instead, our results provide evidences that stabilizing selection favors the optimal intermediate size of males. PMID:26901766

  2. Bigger Is Not Always Better: Females Prefer Males of Mean Body Size in Philautus odontotarsus

    PubMed Central

    Zhu, Bicheng; Wang, Jichao; Zhao, Longhui; Sun, Zhixin; Brauth, Steven E.; Tang, Yezhong; Cui, Jianguo

    2016-01-01

    Most species are believed to evolve larger body sizes over evolutionary time. Previous studies have suggested that sexual selection, through male-male competition and female choice, favors larger males. However, there is little evidence of selection against large size. The female serrate-legged small treefrogs (Philautus odontotarsus) must carry passive males from leks to breeding grounds over relatively long distances after amplexus to find a suitable place to lay eggs. The costs of large male size may therefore decrease mating success due to reduced agility and/or higher energy requirements. Thus, we hypothesized that selection would not favor larger males in P. odontotarsus. Females can assess male body size on the basis of the dominant frequency of male calls in frogs. To assess female P. odontotarsus preferences for a potential mate’s body size, male calls of high, average and low dominant frequency were played back to the females in phonotaxis experiments. Results showed that most females prefer the advertisement call with average dominant frequency. In addition, we compared the body mass distribution of amplectant males with that of single males in nature. The body masses of amplectant males are more narrowly distributed in the intermediate range than that of single males. The phonotaxis results and the data of actual female preferences in the field show that females strongly prefer potential mates of mean body sizes, consistent with the view that, in this species at least, larger males are not always perceived as better by females. In the present study, P. odontotarsus provides an example of an amphibian species in which large size does not have an advantage in mating success for males. Instead, our results provide evidences that stabilizing selection favors the optimal intermediate size of males. PMID:26901766

  3. Boundaries around Group Interaction: A Meta-Analytic Integration of the Effects of Group Size.

    ERIC Educational Resources Information Center

    Mullen, Brian; And Others

    1991-01-01

    Summarizes research comparing boundaries around larger and smaller groups. Finds that the perception of group boundary permatbility varies with group size. Reports a greater perceived distinction between the group and the individual passerby as group size increases. Describes the effects of varying group member proximity. Discusses implications…

  4. A model for group counseling with male pedophiles.

    PubMed

    van Zessen, G

    1990-01-01

    Group treatment programs for pedophiles are often designed for populations of convicted men in closed institutions with limited application to other populations. Treatment is usually focused on reducing the "deviant" sexual arousal and/or acquiring heterosocial skills and eventually establishing the ability to engage in adult heterosexual relationships. A six-week, highly structured program is presented to five men in a non-residential setting. In addition to individual psychotherapy, group counseling is offered. Male pedophiles are trained to talk effectively about common problems surrounding man-boy relationships. Counseling is based on the notion that the emotional, erotic and sexual attraction to boys per se does not need to be legitimized or modified. The attraction, however, can be a source of psychological and social problems that can be handled by using a social support system. Social support for pedophile problems can be obtained from and in interaction with other pedophiles. PMID:2086631

  5. Group D Salmonella Urinary Tract Infection in an Immunocompetent Male

    PubMed Central

    Jehangir, Asad; Poudel, Dilli; Fareedy, Shoaib Bilal; Salman, Ahmed; Qureshi, Anam; Jehangir, Qasim

    2015-01-01

    A 62-year-old male with past medical history of benign prostatic hyperplasia presented to the emergency department with complaints of decreased urinary flow, inability to fully empty his bladder, and gross hematuria. Physical examination was unremarkable. Urinalysis revealed large amount of blood and more than 700 white blood cells suggesting a urinary tract infection. Urine culture grew group D Salmonella greater than 100,000 colony-forming units per mL. He was prescribed 6 weeks of trimethoprim/sulfamethoxazole and had resolution of symptoms. Retrospectively, he reported a 3-day history of watery diarrhea about a week prior to onset of urinary symptoms that was presumed to be the hematogenous source in this case. Urinary tract infection from nontyphoidal Salmonella (NTS) is rare and is usually associated with immunosuppression, chronic diseases, such as diabetes or structural abnormalities of the genitourinary tract. Genitourinary tract abnormalities previously reported in the literature that predispose to nontyphoidal Salmonella urinary tract infection include nephrolithiasis, chronic pyelonephritis, retrovesicular fistula, urethrorectal fistula, hydrocele, and post-TURP. We present an exceedingly uncommon case of 62-year-old male with group D Salmonella urinary tract infection predisposed by his history of benign prostatic hyperplasia. PMID:25984372

  6. Body Size, Rather Than Male Eye Allometry, Explains Chrysomya megacephala (Diptera: Calliphoridae) Activity in Low Light

    PubMed Central

    Smith, J. L.; Palermo, N. A.; Theobald, J. C.; Wells, J. D.

    2015-01-01

    Male Chrysomya megacephala (F.) blow fly compound eyes contain an unusual area of enlarged dorsal facets believed to allow for increased light capture. This region is absent in females and has been hypothesized to aid in mate tracking in low light conditions or at greater distances. Many traits used in the attraction and capture of mates are allometric, growing at different rates relative to body size. Previous reports concerning C. megacephala eye properties did not include measurements of body size, making the relationship between the specialized eye region and body size unclear. We examined different morphological features of the eye among individuals of varying sizes. We found total eye size scaled proportionately to body size, but the number of enlarged dorsal facets increased as body size increased. This demonstrated that larger males have an eye that is morphologically different than smaller males. On the basis of external morphology, we hypothesized that since larger males have larger and a greater number of dorsally enlarged facets, and these facets are believed to allow for increased light capture, larger males would be active in lower light levels than smaller males and females of equal size. In a laboratory setting, larger males were observed to become active earlier in the morning than smaller males, although they did not remain active later in the evening. However, females followed the same pattern at similar light levels suggesting that overall body size rather than specialized male eye morphology is responsible for increased activity under low light conditions. PMID:26411786

  7. Male mate preference and size-assortative mating in convict cichlids: A role for female aggression?

    PubMed

    Bloch, A N; Estela, V J; Leese, J M; Itzkowitz, M

    2016-09-01

    Many monogamous species demonstrate size-assortative mating patterns within natural populations. To better understand the role of intersexual selection in this process, we examined the effect of male preference for female body size in the convict cichlid (Amatitlania siquia). We provided males with a choice between females that differed in size, relative to each other and in relation to the focal male. Based on previous work, we expected males to prefer the largest available female mates across all treatments. Surprisingly, males spent more time near the smaller of two available females, but only when the other female was larger than the male. Additionally, males spent little time with either of two potential female mates when both females were larger than the male. We hypothesized that while males might prefer the largest of available females, female behavior might limit males from acting on this preference. To test this, males were force paired with a smaller or larger female. Pair formation only occurred when the female was smaller than the male, and females that were larger than their male counterparts showed significantly more aggression when compared to smaller females. Together, these data suggest that in the absence of intrasexual competition, male mate preference for large females in convict cichlids might be limited by female aggression. PMID:27444247

  8. Group Therapy Goals: A Comparison of Group Therapy Providers and Male Inmates

    ERIC Educational Resources Information Center

    Morgan, Robert D.; Garland, J. Travis; Rozycki, Alicia T.; Reich, Darcy A.; Wilson, Scott

    2005-01-01

    This study was designed to identify important process and content goals from the perspective of inmates and compare these goals to the goals identified by group therapists in a previous study conducted by Winterowd, Morgan, and Ferrell (2001). Utilizing survey data from 156 incarcerated adult males, an initial confirmatory factor analysis…

  9. Canalization of body size matters for lifetime reproductive success of male predatory mites (Acari: Phytoseiidae)

    PubMed Central

    Walzer, Andreas; Schausberger, Peter

    2014-01-01

    The adaptive canalization hypothesis predicts that highly fitness-relevant traits are canalized via past selection, resulting in low phenotypic plasticity and high robustness to environmental stress. Accordingly, we hypothesized that the level of phenotypic plasticity of male body size of the predatory mites Phytoseiulus persimilis (low plasticity) and Neoseiulus californicus (high plasticity) reflects the effects of body size variation on fitness, especially male lifetime reproductive success (LRS). We first generated small and standard-sized males of P. persimilis and N. californicus by rearing them to adulthood under limited and ample prey supply, respectively. Then, adult small and standard-sized males were provided with surplus virgin females throughout life to assess their mating and reproductive traits. Small male body size did not affect male longevity or the number of fertilized females but reduced male LRS of P. persimilis but not N. californicus. Proximately, the lower LRS of small than standard-sized P. persimilis males correlated with shorter mating durations, probably decreasing the amount of transferred sperm. Ultimately, we suggest that male body size is more strongly canalized in P. persimilis than N. californicus because deviation from standard body size has larger detrimental fitness effects in P. persimilis than N. californicus. © 2014 The Authors. Biological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 889–899. PMID:25132689

  10. Effects of Group Size on Students Mathematics Achievement in Small Group Settings

    ERIC Educational Resources Information Center

    Enu, Justice; Danso, Paul Amoah; Awortwe, Peter K.

    2015-01-01

    An ideal group size is hard to obtain in small group settings; hence there are groups with more members than others. The purpose of the study was to find out whether group size has any effects on students' mathematics achievement in small group settings. Two third year classes of the 2011/2012 academic year were selected from two schools in the…

  11. The Sample Size Needed for the Trimmed "t" Test when One Group Size Is Fixed

    ERIC Educational Resources Information Center

    Luh, Wei-Ming; Guo, Jiin-Huarng

    2009-01-01

    The sample size determination is an important issue for planning research. However, limitations in size have seldom been discussed in the literature. Thus, how to allocate participants into different treatment groups to achieve the desired power is a practical issue that still needs to be addressed when one group size is fixed. The authors focused…

  12. Fluctuating survival selection explains variation in avian group size.

    PubMed

    Brown, Charles R; Brown, Mary Bomberger; Roche, Erin A; O'Brien, Valerie A; Page, Catherine E

    2016-05-01

    Most animal groups vary extensively in size. Because individuals in certain sizes of groups often have higher apparent fitness than those in other groups, why wide group size variation persists in most populations remains unexplained. We used a 30-y mark-recapture study of colonially breeding cliff swallows (Petrochelidon pyrrhonota) to show that the survival advantages of different colony sizes fluctuated among years. Colony size was under both stabilizing and directional selection in different years, and reversals in the sign of directional selection regularly occurred. Directional selection was predicted in part by drought conditions: birds in larger colonies tended to be favored in cooler and wetter years, and birds in smaller colonies in hotter and drier years. Oscillating selection on colony size likely reflected annual differences in food availability and the consequent importance of information transfer, and/or the level of ectoparasitism, with the net benefit of sociality varying under these different conditions. Averaged across years, there was no net directional change in selection on colony size. The wide range in cliff swallow group size is probably maintained by fluctuating survival selection and represents the first case, to our knowledge, in which fitness advantages of different group sizes regularly oscillate over time in a natural vertebrate population. PMID:27091998

  13. Fluctuating survival selection explains variation in avian group size

    USGS Publications Warehouse

    Brown, Charles B.; Brown, Mary Bomberger; Roche, Erin A.; O'brien, Valerie A; Page, Catherine E.

    2016-01-01

    Most animal groups vary extensively in size. Because individuals in certain sizes of groups often have higher apparent fitness than those in other groups, why wide group size variation persists in most populations remains unexplained. We used a 30-y mark–recapture study of colonially breeding cliff swallows (Petrochelidon pyrrhonota) to show that the survival advantages of different colony sizes fluctuated among years. Colony size was under both stabilizing and directional selection in different years, and reversals in the sign of directional selection regularly occurred. Directional selection was predicted in part by drought conditions: birds in larger colonies tended to be favored in cooler and wetter years, and birds in smaller colonies in hotter and drier years. Oscillating selection on colony size likely reflected annual differences in food availability and the consequent importance of information transfer, and/or the level of ectoparasitism, with the net benefit of sociality varying under these different conditions. Averaged across years, there was no net directional change in selection on colony size. The wide range in cliff swallow group size is probably maintained by fluctuating survival selection and represents the first case, to our knowledge, in which fitness advantages of different group sizes regularly oscillate over time in a natural vertebrate population.

  14. 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

  15. Boundaries around Group Interaction: The Effect of Size and Status.

    ERIC Educational Resources Information Center

    Knowles, Eric S.

    The stimulus value of group boundaries was investigated in a field experiment. It was hypothesized that the size of a group and the status of its members would reduce the permeability of a boundary around an interacting group. Two or 4 interacting people of high or low status interrupted the traffic flow in a university hallway. Results indicate…

  16. Epidemiological effects of group size variation in social species

    PubMed Central

    Caillaud, Damien; Craft, Meggan E.; Meyers, Lauren Ancel

    2013-01-01

    Contact patterns in group-structured populations determine the course of infectious disease outbreaks. Network-based models have revealed important connections between group-level contact patterns and the dynamics of epidemics, but these models typically ignore heterogeneities in within-group composition. Here, we analyse a flexible mathematical model of disease transmission in a hierarchically structured wildlife population, and find that increased variation in group size reduces the epidemic threshold, making social animal populations susceptible to a broader range of pathogens. Variation in group size also increases the likelihood of an epidemic for mildly transmissible diseases, but can reduce the likelihood and expected size of an epidemic for highly transmissible diseases. Further, we introduce the concept of epidemiological effective group size, which we define to be the group size of a hypothetical population containing groups of identical size that has the same epidemic threshold as an observed population. Using data from the Serengeti Lion Project, we find that pride-living Serengeti lions are epidemiologically comparable to a homogeneous population with up to 20 per cent larger prides. PMID:23576784

  17. The implicit identity effect: identity primes, group size, and helping.

    PubMed

    Levine, Mark; Cassidy, Clare; Jentzsch, Ines

    2010-12-01

    Three studies consider the implicit bystander effect in the light of recent advances in social identity approaches to helping. Drawing on the social identity model of deindividuation effects we argue that the implicit bystander effect is shaped not by the number of others imagined, but by who those others are imagined to be. Studies 1 and 2 demonstrate that, when group membership is primed, increasing group size can facilitate helping in line with the norms and values of the group. Study 3 explores mediation processes in group level helping. As group size increases, female participants react faster to words associated with communalism when others are imagined as women rather than strangers. The paper demonstrates that group size and helping behaviour is qualified by an implicit identity effect. PMID:20122306

  18. Costs and Benefits to Pregnant Male Pipefish Caring for Broods of Different Sizes

    PubMed Central

    Sagebakken, Gry; Ahnesjö, Ingrid; Kvarnemo, Charlotta

    2016-01-01

    Trade-offs between brood size and offspring size, offspring survival, parental condition or parental survival are classic assumptions in life history biology. A reduction in brood size may lessen these costs of care, but offspring mortality can also result in an energetic gain, if parents are able to utilize the nutrients from the demised young. Males of the broad-nosed pipefish (Syngnathus typhle) care for the offspring by brooding embryos in a brood pouch. Brooding males can absorb nutrients that emanate from embryos, and there is often a reduction in offspring number over the brooding period. In this study, using two experimentally determined brood sizes (partially and fully filled brood pouches), we found that full broods resulted in larger number of developing offspring, despite significantly higher absolute and relative embryo mortality, compared to partial broods. Male survival was also affected by brood size, with males caring for full broods having poorer survival, an effect that together with the reduced embryo survival was found to negate the benefit of large broods. We found that embryo mortality was lower when the brooding males were in good initial condition, that embryos in broods with low embryo mortality weighed more, and surprisingly, that males in higher initial condition had embryos of lower weight. Brood size, however, did not affect embryo weight. Male final condition, but not initial condition, correlated with higher male survival. Taken together, our results show costs and benefits of caring for large brood sizes, where the numerical benefits come with costs in terms of both embryo survival and survival of the brooding father, effects that are often mediated via male condition. PMID:27243937

  19. Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths

    PubMed Central

    Symonds, Matthew RE; Johnson, Tamara L; Elgar, Mark A

    2012-01-01

    The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae. PMID:22408739

  20. Toward Designing Optimal Problem-Solving Procedures: Comparisons of Male and Female Interacting Groups.

    ERIC Educational Resources Information Center

    Mathews, Robert C.; And Others

    1982-01-01

    Compared performances for male and female groups using three different group problem-solving procedures: unstructured, structured-open, and structured-forced. Results indicated that female groups performed better with the structured-forced procedure than with the structured-open procedure. Male groups performed better with the structured-open…

  1. Switching photo-stimulated males between groups of goats does not improve the reproductive response during the male effect.

    PubMed

    Loya-Carrera, J; Bedos, M; Ponce-Covarrubias, J L; Hernández, H; Chemineau, P; Keller, M; Delgadillo, J A

    2014-04-01

    We aimed to determine whether the daily exchange of photo-stimulated males among subgroups of females improved the reproductive response of anestrous goats exposed to males. Bucks were rendered sexually active during the rest season by exposure to 2.5 months of long days from November 1st. In April, males (n=3) were put in contact with three subgroups of anestrous goats (one male per 12 females) where they remained throughout the study, constituting the fixed-group. Other males (n=3) were put in contact with three subgroups of females (one male per 11-12 females) and were rotated daily among them, constituting the rotated-group. The sexual behavior of all males was registered from 08:00 to 09:00 on days 0, 1, 2, and 8 after exchanging the males from the subgroups of females. Ovulation and pregnancy rates were determined by transrectal ultrasonography. The occurrences of ano-genital sniffing, nudging (days 1, 2, and 8), and mounting attempts (days 2 and 8) were greater in the rotated than in the fixed-group (P<0.01). The proportions of females that ovulated did not differ among goats from the fixed (92%) and rotated-group (94%; P>0.05). The proportion of pregnant females and the fertility at kidding did not differ between those from the rotated (79% and 59%) and fixed-group (83% and 61%; P>0.05). We conclude that the daily exchange of photo-stimulated males among subgroups induced an increase of their sexual behavior, but does not improve the pregnancy rates in seasonal anestrous goats. PMID:24602505

  2. Infants use relative numerical group size to infer social dominance.

    PubMed

    Pun, Anthea; Birch, Susan A J; Baron, Andrew Scott

    2016-03-01

    Detecting dominance relationships, within and across species, provides a clear fitness advantage because this ability helps individuals assess their potential risk of injury before engaging in a competition. Previous research has demonstrated that 10- to 13-mo-old infants can represent the dominance relationship between two agents in terms of their physical size (larger agent = more dominant), whereas younger infants fail to do so. It is unclear whether infants younger than 10 mo fail to represent dominance relationships in general, or whether they lack sensitivity to physical size as a cue to dominance. Two studies explored whether infants, like many species across the animal kingdom, use numerical group size to assess dominance relationships and whether this capacity emerges before their sensitivity to physical size. A third study ruled out an alternative explanation for our findings. Across these studies, we report that infants 6-12 mo of age use numerical group size to infer dominance relationships. Specifically, preverbal infants expect an agent from a numerically larger group to win in a right-of-way competition against an agent from a numerically smaller group. In addition, this is, to our knowledge, the first study to demonstrate that infants 6-9 mo of age are capable of understanding social dominance relations. These results demonstrate that infants' understanding of social dominance relations may be based on evolutionarily relevant cues and reveal infants' early sensitivity to an important adaptive function of social groups. PMID:26884199

  3. Infants use relative numerical group size to infer social dominance

    PubMed Central

    Pun, Anthea; Birch, Susan A. J.; Baron, Andrew Scott

    2016-01-01

    Detecting dominance relationships, within and across species, provides a clear fitness advantage because this ability helps individuals assess their potential risk of injury before engaging in a competition. Previous research has demonstrated that 10- to 13-mo-old infants can represent the dominance relationship between two agents in terms of their physical size (larger agent = more dominant), whereas younger infants fail to do so. It is unclear whether infants younger than 10 mo fail to represent dominance relationships in general, or whether they lack sensitivity to physical size as a cue to dominance. Two studies explored whether infants, like many species across the animal kingdom, use numerical group size to assess dominance relationships and whether this capacity emerges before their sensitivity to physical size. A third study ruled out an alternative explanation for our findings. Across these studies, we report that infants 6–12 mo of age use numerical group size to infer dominance relationships. Specifically, preverbal infants expect an agent from a numerically larger group to win in a right-of-way competition against an agent from a numerically smaller group. In addition, this is, to our knowledge, the first study to demonstrate that infants 6–9 mo of age are capable of understanding social dominance relations. These results demonstrate that infants’ understanding of social dominance relations may be based on evolutionarily relevant cues and reveal infants’ early sensitivity to an important adaptive function of social groups. PMID:26884199

  4. Craniodental features in male Mandrillus may signal size and fitness: an allometric approach.

    PubMed

    Klopp, Emily B

    2012-04-01

    According to a hypothesis in the broader mammalian literature, secondary sexual characteristics that have evolved to signal fitness and size to other conspecifics should exhibit positive allometry across adult males within a species. Here this hypothesis is tested in the genus Mandrillus. The overbuilding of bony features in larger individuals necessitates a functional explanation as bone is metabolically expensive to produce and maintain. Canine size and size of the maxillary ridge are scaled against a body size surrogate in intraspecific samples of male Mandrillus sphinx (mandrills) and Mandrillus leucophaeus (drills). Areal dimensions are weighted more heavily as they represent the size of a feature as it is viewed by individuals. Measures of the maxillary ridge and canine tooth are significantly correlated with the size surrogate and scale with positive allometry in both samples supporting the hypothesis that these features function to advertise a male's body size and fitness to other males competing for mates and potential discerning females. This is the first study in primates to test for intraspecific positive allometric scaling of bony facial features in adult males based on a theory of fitness signaling and sexual selection. PMID:22328467

  5. Consultation for Small-Sized Penis in the Egyptian Males: A Case Control Study.

    PubMed

    Salama, Nader

    2016-05-01

    This study aimed to report penile dimensions in adult Egyptian males consulting for small-sized penis (SSP) and describe their demographics and andrological profile. A case control study was designed through retrospective data analysis of patients (n = 239) seeking advice for SSP and a control group (n = 59). This included sociodemographics, other andrological complaints, and penile dimensions (pendulous length [PL], penopubic or total length [TL], and circumference [CF]) at flaccid and erect states and the size of the prepubic fatty pad. The results reported that most patients were single, students, and smokers and had not completed a university education. Several patients reported falsely premature ejaculation (PE), penile curvature (PC), and small-sized testes. Most penile dimensions of the patients (mean, cm) were significantly lower than those of the controls, whether in flaccid (PL: 7.4 vs. 8.05, p = .008; CF: 8.7 vs. 8.98, p = .026) or erect state (PL: 11.8 vs. 13, p = .000; TL: 14.2 vs. 15, p = .000; CF: 11.3 vs. 11.8, p = .003). However, no patient presented with a pendulous penile length <4 cm in flaccid or <7 cm in erect state. In conclusion, Egyptian men consulting for SSP did not have true small organs, but their penile dimensions were slightly smaller than those of men without such complaint. The proper sexual education program is highly advisable in these situations to avoid the myths and misconceptions about sexuality. PMID:25563384

  6. 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

  7. Learning Together While Designing: Does Group Size Make a Difference?

    NASA Astrophysics Data System (ADS)

    Apedoe, Xornam S.; Ellefson, Michelle R.; Schunn, Christian D.

    2012-02-01

    As the use of project-based learning becomes more frequent in the K-12 science classroom, and in chemistry classrooms in particular, teachers have begun to identify practical questions about implementation that should be addressed empirically. One such question concerns whether there is an ideal group size that fosters individual student achievement. The current project was designed to assess how group size might impact student chemistry content learning in a project-based learning environment, and how well students are prepared to transfer this new knowledge to other relevant areas. The results indicated that particular conditions (e.g. advanced classrooms) interact with group size (a seemingly superficial feature) to differentially influence the depth and level of student learning related to the unit and student's ability to transfer his/her knowledge outside of the context of a project-based learning unit.

  8. Female mate preferences for male body size and shape promote sexual isolation in threespine sticklebacks

    PubMed Central

    Head, Megan L; Kozak, Genevieve M; Boughman, Janette W

    2013-01-01

    Female mate preferences for ecologically relevant traits may enhance natural selection, leading to rapid divergence. They may also forge a link between mate choice within species and sexual isolation between species. Here, we examine female mate preference for two ecologically important traits: body size and body shape. We measured female preferences within and between species of benthic, limnetic, and anadromous threespine sticklebacks (Gasterosteus aculeatus species complex). We found that mate preferences differed between species and between contexts (i.e., within vs. between species). Within species, anadromous females preferred males that were deep bodied for their size, benthic females preferred larger males (as measured by centroid size), and limnetic females preferred males that were more limnetic shaped. In heterospecific mating trials between benthics and limnetics, limnetic females continued to prefer males that were more limnetic like in shape when presented with benthic males. Benthic females showed no preferences for size when presented with limnetic males. These results show that females use ecologically relevant traits to select mates in all three species and that female preference has diverged between species. These results suggest that sexual selection may act in concert with natural selection on stickleback size and shape. Further, our results suggest that female preferences may track adaptation to local environments and contribute to sexual isolation between benthic and limnetic sticklebacks. PMID:23919161

  9. The relation between visualization size, grouping, and user performance.

    PubMed

    Gramazio, Connor C; Schloss, Karen B; Laidlaw, David H

    2014-12-01

    In this paper we make the following contributions: (1) we describe how the grouping, quantity, and size of visual marks affects search time based on the results from two experiments; (2) we report how search performance relates to self-reported difficulty in finding the target for different display types; and (3) we present design guidelines based on our findings to facilitate the design of effective visualizations. Both Experiment 1 and 2 asked participants to search for a unique target in colored visualizations to test how the grouping, quantity, and size of marks affects user performance. In Experiment 1, the target square was embedded in a grid of squares and in Experiment 2 the target was a point in a scatterplot. Search performance was faster when colors were spatially grouped than when they were randomly arranged. The quantity of marks had little effect on search time for grouped displays ("pop-out"), but increasing the quantity of marks slowed reaction time for random displays. Regardless of color layout (grouped vs. random), response times were slowest for the smallest mark size and decreased as mark size increased to a point, after which response times plateaued. In addition to these two experiments we also include potential application areas, as well as results from a small case study where we report preliminary findings that size may affect how users infer how visualizations should be used. We conclude with a list of design guidelines that focus on how to best create visualizations based on grouping, quantity, and size of visual marks. PMID:26356909

  10. Relationship between pubertal timing and body size in underfed male rats.

    PubMed

    Glass, A R; Anderson, J; Herbert, D; Vigersky, R A

    1984-07-01

    A direct connection has been proposed between body size and sexual maturation by the critical body weight and critical body fat hypotheses. To test these theories in male rats, we compared the degree of sexual maturation in animals with reduced growth rate due to undernutrition with that in weight-matched but normally fed rats. Underfed rats had significantly larger prostate, seminal vesicle, and testis weights than the weight-matched normally fed controls at the three time points studied: the early pubertal period (approximate time of onset of rising serum testosterone), late pubertal period (approximate time of appearance of mature spermatids), and young adult period. At the first time point, testes of underfed rats, but not those of normally fed, weight-matched controls, showed mature step 19 spermatids, and serum testosterone was significantly higher in the underfed animals. At all time points, serum LH levels were similar in both groups, while serum FSH levels were significantly lower in the underfed rats at all points. The Lee index, an index of fatness, was significantly lower in the underfed rats. The current study indicates that underfed rats are more sexually mature than normally fed controls of the same weight despite having a lower percentage of body fat. These findings do not support the critical body weight or critical body fat hypotheses of puberty in male rats. PMID:6428861

  11. Plasma steroid concentrations and male phallus size in juvenile alligators from seven Florida lakes

    USGS Publications Warehouse

    Guillette, L.J., Jr.; Woodward, A.R.; Crain, D.A.; Pickford, D.B.; Rooney, A.A.; Percival, H.F.

    1999-01-01

    Neonatal and juvenile alligators from contaminated Lake Apopka in central Florida exhibit abnormal plasma sex steroid concentrations as well as morphological abnormalities of the gonad and phallus. This study addresses whether similar abnormalities occur in juvenile alligators inhabiting six other lakes in Florida. For analysis, animals were partitioned into two subsets, animals 40-79 cm total length (1-3 years old) and juveniles 80-130 cm total length (3-7 years old). Plasma testosterone (T) concentrations were lower in small males from lakes Apopka, Griffin, and Jessup than from Lake Woodruff National Wildlife Refuge (NWR). Similar differences were observed in the larger juveniles, with males from lakes Jessup, Apopka, and Okeechobee having lower plasma T concentrations than Lake Woodruff males. Plasma estradiol-17?? (E2) concentrations were significantly elevated in larger juvenile males from Lake Apopka compared to Lake Woodruff NWR. When compared to small juvenile females from Lake Woodruff NWR, females from lakes Griffin, Apopka, Orange, and Okeechobee had elevated plasma E2 concentrations. Phallus size was significantly smaller in males from lakes Griffin and Apopka when compared to males from Lake Woodruff NWR. An association existed between body size and phallus size on all lakes except Lake Apopka and between phallus size and plasma T concentration on all lakes except lakes Apopka and Orange. Multiple regression analysis, with body size and plasma T concentration as independent covariables, explained the majority of the variation in phallus size on all lakes. These data suggest that the differences in sex steroids and phallus size observed in alligators from Lake Apopka are not limited to that lake, nor to one with a history of a major pesticide spill. Further work examining the relationship of sex steroids and phallus size with specific biotic and abiotic factors, such as antiandrogenic or estrogenic contaminants, is needed.

  12. Learning Together while Designing: Does Group Size Make a Difference?

    ERIC Educational Resources Information Center

    Apedoe, Xornam S.; Ellefson, Michelle R.; Schunn, Christian D.

    2012-01-01

    As the use of project-based learning becomes more frequent in the K-12 science classroom, and in chemistry classrooms in particular, teachers have begun to identify practical questions about implementation that should be addressed empirically. One such question concerns whether there is an ideal group size that fosters individual student…

  13. 48 CFR 1602.170-13 - Similarly sized subscriber groups.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 6 2012-10-01 2012-10-01 false Similarly sized subscriber groups. 1602.170-13 Section 1602.170-13 Federal Acquisition Regulations System OFFICE OF PERSONNEL MANAGEMENT FEDERAL EMPLOYEES HEALTH BENEFITS ACQUISITION REGULATION GENERAL DEFINITIONS OF WORDS AND TERMS Definitions of FEHBP Terms...

  14. 48 CFR 1602.170-13 - Similarly sized subscriber groups.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 6 2013-10-01 2013-10-01 false Similarly sized subscriber groups. 1602.170-13 Section 1602.170-13 Federal Acquisition Regulations System OFFICE OF PERSONNEL MANAGEMENT FEDERAL EMPLOYEES HEALTH BENEFITS ACQUISITION REGULATION GENERAL DEFINITIONS OF WORDS AND TERMS Definitions of FEHBP Terms...

  15. The effects of familiarity and group size on mating preferences in the guppy, Poecilia reticulata.

    PubMed

    Mariette, M M; Zajitschek, S R K; Garcia, C M; Brooks, R C

    2010-08-01

    In recent years, it has become evident that frequency dependence in the attractiveness of a particular phenotype to mates can contribute to the maintenance of polymorphism. However, these preferences for rare and unfamiliar male phenotypes have only been demonstrated in small, controlled experiments. Here, we tested the preference for unfamiliar mates in groups of six to 96 individuals over 13 days, in the guppy (Poecilia reticulata). We observed individual behaviour in situ to test whether fish discriminate two unfamiliar individuals among many familiar ones. We found that unfamiliar males and females were preferred over the familiar fishes in all groups and that this effect decayed over time. Increasing group sizes and levels of sexual activity did not hamper the preference for unfamiliar mates, providing further support for the role of frequency dependent mate choice in the maintenance of trait polymorphism in natural populations. PMID:20626544

  16. Neither male gonadal androgens nor female reproductive costs drive development of sexual size dimorphism in lizards.

    PubMed

    Starostová, Zuzana; Kubička, Lukáš; Golinski, Alison; Kratochvíl, Lukáš

    2013-05-15

    Sexual size dimorphism (SSD) is an extensively studied phenomenon in animals, including reptiles, but the proximate mechanism of its development is poorly understood. The most pervasive candidates are: (1) androgen-mediated control of growth, i.e. a positive effect of gonadal androgens (testosterone) on male growth in male-larger species, and a negative effect in female-larger species; and (2) sex-specific differences in energy allocation to growth, e.g. sex with larger reproductive costs should result in smaller body size. We tested these hypotheses in adults of the male-larger lizard Paroedura picta by conducting castrations with and without testosterone implants in males and manipulating reproductive status in females. Castration or testosterone replacement had no significant effect on final body length in males. High investment to reproduction had no significant effect on final body length in intact females. Interestingly, ovariectomized females and females with testosterone implants grew to larger body size than intact females. We did not find support for either of the above hypotheses and suggest that previously reported effects of gonadal androgens on growth in male lizards could be a consequence of altered behaviour or social status in manipulated individuals. Exogenous testosterone in females led to decreased size of ovaries; its effect on body size may be caused by interference with normal ovarian function. We suggest that ovarian factors, perhaps estrogens, not reproductive costs, can modify growth in female lizards and may thus contribute to the development of SSD. This hypothesis is largely supported by published results on the effect of testosterone treatment or ovariectomy on body size in female squamates. PMID:23393279

  17. Asymmetric forceps increase fighting success among males of similar size in the maritime earwig

    PubMed Central

    Munoz, Nicole E.; Zink, Andrew G.

    2012-01-01

    Extreme asymmetric morphologies are hypothesized to serve an adaptive function that counteracts sexual selection for symmetry. However direct tests of function for asymmetries are lacking, particularly in the context of animal weapons. The weapon of the maritime earwig, Anisolabis maritima, exhibits sizeable variation in the extent of directional asymmetry within and across body sizes, making it an ideal candidate for investigating the function of asymmetry. In this study, we characterized the extent of weapon asymmetry, characterized the manner in which asymmetric weapons are used in contests, staged dyadic contests between males of different size classes and analyzed the correlates of fighting success. In contests between large males, larger individuals won more fights and emerged as the dominant male. In contests between small males, however, weapon asymmetry was more influential in predicting overall fighting success than body size. This result reveals an advantage of asymmetric weaponry among males that are below the mean size in the population. A forceps manipulation experiment suggests that asymmetry may be an indirect, correlate of a morphologically independent factor that affects fighting ability. PMID:22984320

  18. The Effects of Sexual Composition and Group Size on Individual Effort.

    ERIC Educational Resources Information Center

    Jackson, Jeffrey M.; And Others

    This experiment was designed to test the motivation to perform a task for males and females in mixed and same-sex groups. Individuals in homogeneous groups (four males or four females) or heterogeneous groups (two males and two females) clapped their hands alone, in pairs and in foursomes. People exerted more effort alone than in groups,…

  19. Establishment of a captive all-male group of proboscis monkey (Nasalis larvatus) at the Singapore Zoo.

    PubMed

    Sha, John Chih Mun; Alagappasamy, Sam; Chandran, Subash; Cho, Khin Maung; Guha, Biswajit

    2013-01-01

    Surplus male proboscis monkeys at the Singapore Zoo pose a considerable problem for maintenance and maximizing of exhibition potential. In 2008, a new exhibit was constructed to house and display a group of six proboscis monkey males born in Singapore Zoo. To document and monitor the all-male group establishment in the new exhibit, we conducted observations on intragroup interactions between the monkeys, spatial use of their new exhibit, and visitor effects on their behavior. We found contact aggressive interactions between the monkeys to be consistently lower than noncontact aggressive interactions and by week six of introduction to the new exhibit, contact aggression was almost nonevident. Affiliative interactions also developed between individuals in the group, with an interface of aggressive and socioreconcilatory behavior influenced by food competition and a dominance hierarchy. This was evident from significantly higher overall aggression and affiliation during feeding times compared to nonfeeding times, and this was reduced when food competition was mitigated by modifying the feeding regime. We measured the groups' spatial use of the exhibit and the relation to behavior, crowd size, and density. Our results showed that the proboscis monkeys utilized the available exhibit space, were largely unaffected by visitor crowd size and density, and were able to exhibit a variety of natural behaviors, including swimming. Our accomplishment in maintaining and displaying an all-male group of proboscis monkeys in captivity provides viable options for more comprehensive captive management and breeding programs for this endangered species. PMID:22549979

  20. Mountain gorilla ranging patterns: influence of group size and group dynamics.

    PubMed

    Caillaud, Damien; Ndagijimana, Felix; Giarrusso, Anthony J; Vecellio, Veronica; Stoinski, Tara S

    2014-08-01

    Since the 1980s, the Virunga mountain gorilla population has almost doubled, now reaching 480 individuals living in a 430-km(2) protected area. Analysis of the gorillas' ranging patterns can provide critical information on the extent and possible effects of competition for food and space. We analyzed 12 years of daily ranging data and inter-group encounter data collected on 11 gorilla groups monitored by the Karisoke Research Center in Rwanda. During that period, the study population increased in size by almost 50% and the number of groups tripled. Groups had small yearly home ranges compared to other known gorilla populations, with an average 90% kernel density estimate of 8.07 km2 and large between-group variations (3.17-23.59 km2). Most groups had consistent home range location over the course of the study but for some, we observed gradual range shifts of up to 4 km. Neighboring groups displayed high home range overlap, which increased dramatically after the formation of new groups. On average, each group used only 28.6% of its 90% kernel home range exclusively, and in some areas up to six different groups had overlapping home ranges with little or no exclusive areas. We found a significant intra-group positive relationship between the number of weaned individuals in a group and the home range size, but the fitted models only explained 17.5% and 13.7% of the variance in 50% and 90% kernel home range size estimates, respectively. This suggests that despite the increase in size, the study population is not yet experiencing marked effects of feeding competition. However, the increase in home range overlap resulting from the formation of new groups led to a sixfold increase in the frequency of inter-group encounters, which exposes the population to elevated risks of fight-related injuries and infanticide. PMID:24573634

  1. The Sex Determination Gene transformer Regulates Male-Female Differences in Drosophila Body Size

    PubMed Central

    Rideout, Elizabeth J.; Narsaiya, Marcus S.; Grewal, Savraj S.

    2015-01-01

    Almost all animals show sex differences in body size. For example, in Drosophila, females are larger than males. Although Drosophila is widely used as a model to study growth, the mechanisms underlying this male-female difference in size remain unclear. Here, we describe a novel role for the sex determination gene transformer (tra) in promoting female body growth. Normally, Tra is expressed only in females. We find that loss of Tra in female larvae decreases body size, while ectopic Tra expression in males increases body size. Although we find that Tra exerts autonomous effects on cell size, we also discovered that Tra expression in the fat body augments female body size in a non cell-autonomous manner. These effects of Tra do not require its only known targets doublesex and fruitless. Instead, Tra expression in the female fat body promotes growth by stimulating the secretion of insulin-like peptides from insulin producing cells in the brain. Our data suggest a model of sex-specific growth in which body size is regulated by a previously unrecognized branch of the sex determination pathway, and identify Tra as a novel link between sex and the conserved insulin signaling pathway. PMID:26710087

  2. The Sex Determination Gene transformer Regulates Male-Female Differences in Drosophila Body Size.

    PubMed

    Rideout, Elizabeth J; Narsaiya, Marcus S; Grewal, Savraj S

    2015-12-01

    Almost all animals show sex differences in body size. For example, in Drosophila, females are larger than males. Although Drosophila is widely used as a model to study growth, the mechanisms underlying this male-female difference in size remain unclear. Here, we describe a novel role for the sex determination gene transformer (tra) in promoting female body growth. Normally, Tra is expressed only in females. We find that loss of Tra in female larvae decreases body size, while ectopic Tra expression in males increases body size. Although we find that Tra exerts autonomous effects on cell size, we also discovered that Tra expression in the fat body augments female body size in a non cell-autonomous manner. These effects of Tra do not require its only known targets doublesex and fruitless. Instead, Tra expression in the female fat body promotes growth by stimulating the secretion of insulin-like peptides from insulin producing cells in the brain. Our data suggest a model of sex-specific growth in which body size is regulated by a previously unrecognized branch of the sex determination pathway, and identify Tra as a novel link between sex and the conserved insulin signaling pathway. PMID:26710087

  3. Metastable structures and size effects in small group dynamics

    PubMed Central

    Lauro Grotto, Rosapia; Guazzini, Andrea; Bagnoli, Franco

    2014-01-01

    In his seminal works on group dynamics Bion defined a specific therapeutic setting allowing psychoanalytic observations on group phenomena. In describing the setting he proposed that the group was where his voice arrived. This physical limit was later made operative by assuming that the natural dimension of a therapeutic group is around 12 people. Bion introduced a theory of the group aspects of the mind in which proto-mental individual states spontaneously evolve into shared psychological states that are characterized by a series of features: (1) they emerge as a consequence of the natural tendency of (both conscious and unconscious) emotions to combine into structured group patterns; (2) they have a certain degree of stability in time; (3) they tend to alternate so that the dissolution of one is rapidly followed by the emergence of another; (4) they can be described in qualitative terms according to the nature of the emotional mix that dominates the state, in structural terms by a kind of typical “leadership” pattern, and in “cognitive” terms by a set of implicit expectations that are helpful in explaining the group behavior (i.e., the group behaves “as if” it was assuming that). Here we adopt a formal approach derived from Socio-physics in order to explore some of the structural and dynamic properties of this small group dynamics. We will described data from an analytic DS model simulating small group interactions of agents endowed with a very simplified emotional and cognitive dynamic in order to assess the following main points: (1) are metastable collective states allowed to emerge in the model and if so, under which conditions in the parameter space? (2) can these states be differentiated in structural terms? (3) to what extent are the emergent dynamic features of the systems dependent of the system size? We will finally discuss possible future applications of the quantitative descriptions of the interaction structure in the small group clinical

  4. Parietal cortex mediates perceptual Gestalt grouping independent of stimulus size.

    PubMed

    Grassi, Pablo R; Zaretskaya, Natalia; Bartels, Andreas

    2016-06-01

    The integration of local moving elements into a unified gestalt percept has previously been linked to the posterior parietal cortex. There are two possible interpretations for the lack of involvement of other occipital regions. The first is that parietal cortex is indeed uniquely functionally specialized to perform grouping. Another possibility is that other visual regions can perform grouping as well, but that the large spatial separation of the local elements used previously exceeded their neurons' receptive field (RF) sizes, preventing their involvement. In this study we distinguished between these two alternatives. We measured whole-brain activity using fMRI in response to a bistable motion illusion that induced mutually exclusive percepts of either an illusory global Gestalt or of local elements. The stimulus was presented in two sizes, a large version known to activate IPS only, and a version sufficiently small to fit into the RFs of mid-level dorsal regions such as V5/MT. We found that none of the separately localized motion regions apart from parietal cortex showed a preference for global Gestalt perception, even for the smaller version of the stimulus. This outcome suggests that grouping-by-motion is mediated by a specialized size-invariant mechanism with parietal cortex as its anatomical substrate. PMID:26975554

  5. Group size adjustment to ecological demand in a cooperative breeder

    PubMed Central

    Zöttl, Markus; Frommen, Joachim G.; Taborsky, Michael

    2013-01-01

    Environmental factors can determine which group size will maximize the fitness of group members. This is particularly important in cooperative breeders, where group members often serve different purposes. Experimental studies are yet lacking to check whether ecologically mediated need for help will change the propensity of dominant group members to accept immigrants. Here, we manipulated the perceived risk of predation for dominant breeders of the cooperatively breeding cichlid fish Neolamprologus pulcher to test their response to unrelated and previously unknown immigrants. Potential immigrants were more readily accepted if groups were exposed to fish predators or egg predators than to herbivorous fish or control situations lacking predation risk. Our data are consistent with both risk dilution and helping effects. Egg predators were presented before spawning, which might suggest that the fish adjust acceptance rates also to a potential future threat. Dominant group members of N. pulcher apparently consider both present and future need of help based on ecological demand. This suggests that acceptance of immigrants and, more generally, tolerance of group members on demand could be a widespread response to ecological conditions in cooperatively breeding animals. PMID:23390105

  6. Group Therapy Intervention for Male Batterers: A Microethnographic Study.

    ERIC Educational Resources Information Center

    Pandya, Varsha; Gingerich, Wallace J.

    2002-01-01

    The study discussed in this article describes change processes in abusers and examines the dynamics of unsuccessful processes. In doing so, this study provides a useful evaluation of group therapy as it is offered to batterers. Implications for microethnographic methods are discussed for social work students learning to evaluate their practice.…

  7. The Ontogeny of Sexual Size Dimorphism of a Moth: When Do Males and Females Grow Apart?

    PubMed Central

    Stillwell, R. Craig; Daws, Andrew; Davidowitz, Goggy

    2014-01-01

    Sexual dimorphism in body size (sexual size dimorphism) is common in many species. The sources of selection that generate the independent evolution of adult male and female size have been investigated extensively by evolutionary biologists, but how and when females and males grow apart during ontogeny is poorly understood. Here we use the hawkmoth, Manduca sexta, to examine when sexual size dimorphism arises by measuring body mass every day during development. We further investigated whether environmental variables influence the ontogeny of sexual size dimorphism by raising moths on three different diet qualities (poor, medium and high). We found that size dimorphism arose during early larval development on the highest quality food treatment but it arose late in larval development when raised on the medium quality food. This female-biased dimorphism (females larger) increased substantially from the pupal-to-adult stage in both treatments, a pattern that appears to be common in Lepidopterans. Although dimorphism appeared in a few stages when individuals were raised on the poorest quality diet, it did not persist such that male and female adults were the same size. This demonstrates that the environmental conditions that insects are raised in can affect the growth trajectories of males and females differently and thus when dimorphism arises or disappears during development. We conclude that the development of sexual size dimorphism in M. sexta occurs during larval development and continues to accumulate during the pupal/adult stages, and that environmental variables such as diet quality can influence patterns of dimorphism in adults. PMID:25184664

  8. Dominance, body size and internal relatedness influence male reproductive success in eastern grey kangaroos (Macropus giganteus).

    PubMed

    Miller, Emily J; Eldridge, Mark D B; Cooper, Desmond W; Herbert, Catherine A

    2010-01-01

    Knowledge of the determinants of reproductive success is essential for understanding the adaptive significance of particular traits. The present study examined whether particular behavioural, morphological, physiological or genetic traits were correlated with male dominance and reproductive success using three semi-free-ranging captive populations (n = 98) of the eastern grey kangaroo (Macropus giganteus). The morphological traits measured included bodyweight, head, forearm, tail, pes and leg length, forearm and bicep circumference, and testis size. Blood samples were collected to determine serum testosterone concentrations. All individuals were typed for 10 microsatellite loci and paternity determined for each pouch young. To determine the influence of relatedness and genetic diversity on male reproductive success, internal relatedness, standardised heterozygosity and mean d(2) were calculated. Dominant males sired a significantly higher proportion of offspring than smaller, lower-ranked males and had higher testosterone concentrations. Males that sired offspring were significantly heavier and had larger body size. Sires were significantly more heterozygous and genetically dissimilar to breeding females than non-sires. Despite the wealth of knowledge on the social organisation of kangaroos, this is the first study to assign parentage and male reproductive success using molecular evidence. PMID:20188027

  9. Early life overnutrition induced by litter size manipulation decreases social play behavior in adolescent male rats.

    PubMed

    Carvalho, Ana Laura O; Ferri, Bárbara G; de Sousa, Francielly A Lopes; Vilela, Fabiana C; Giusti-Paiva, Alexandre

    2016-10-01

    Several studies have investigated the effects of artificial litter size adjustment on offspring development. Social play behavior is important for neurobehavioral development and is impaired in several developmental psychiatric disorders. This study therefore investigated the effect of litter size on play behavior in adolescent rats. On postnatal day (PND) 2, litters were adjusted to a small litter (SL) size of 3 pups per dam or normal litter (NL) size of 12 pups per dam. Maternal behaviors scored daily during the first week of lactation (PND2-8) revealed that arched nursing and pup licking behaviors were increased in dams with SLs versus those with NLs. SL offspring exhibited accelerated weight gain and advanced development of physical landmarks and reflexes, possibly due to overnutrition. Social isolation lasting 3.5h prior to social play behavioral testing produced a higher frequency and duration of pouncing, pinning, sniffing, and grooming in both male and female offspring. However, male SL offspring exhibited a lower frequency of pouncing and pinning when compared with male NL offspring, while no litter size-dependent differences were observed in social behaviors unrelated to play (sniffing and grooming). These findings identify a possible sexually dimorphic influence of litter size in the development of social behavior. Given that social behaviors such as play behavior are vital for normal cognitive and social development, these findings have important implications for developmental and neuropsychiatric research. PMID:27469432

  10. Estimation of Tooth Size Discrepancies among Different Malocclusion Groups

    PubMed Central

    Bala, Madhu; Goyal, Virender

    2014-01-01

    ABSTRACT Regards and Tribute: Late Dr Narender Hasija was a mentor and visionary in the light of knowledge and experience. We pay our regards with deepest gratitude to the departed soul to rest in peace. Bolton’s ratios help in estimating overbite, overjet relationships, the effects of contemplated extractions on posterior occlusion, incisor relationships and identification of occlusal misfit produced by tooth size discrepancies. Aim: To determine any difference in tooth size discrepancy in anterior as well as overall ratio in different malocclusions and comparison with Bolton’s study. Materials and methods: After measuring the teeth on all 100 patients, Bolton’s analysis was performed. Results were compared with Bolton’s means and standard deviations. The results were also subjected to statistical analysis. Results show that the mean and standard deviations of ideal occlusion cases are comparable with those Bolton but, when the mean and standard deviation of malocclusion groups are compared with those of Bolton, the values of standard deviation are higher, though the mean is comparable. How to cite this article: Hasija N, Bala M, Goyal V. Estimation of Tooth Size Discrepancies among Different Malocclusion Groups. Int J Clin Pediatr Dent 2014;7(2):82-85. PMID:25356005

  11. Effective population size in eusocial Hymenoptera with worker-produced males

    PubMed Central

    Nomura, T; Takahashi, J

    2012-01-01

    In many eusocial Hymenoptera, a proportion of males are produced by workers. To assess the effect of male production by workers on the effective population size Ne, a general expression of Ne in Hymenoptera with worker-produced males is derived on the basis of the genetic drift in the frequency of a neutral allele. Stochastic simulation verifies that the obtained expression gives a good prediction of Ne under a wide range of conditions. Numerical computation with the expression indicates that worker reproduction generally reduces Ne. The reduction can be serious in populations with a unity or female-biased breeding sex ratio. Worker reproduction may increase Ne in populations with a male-biased breeding sex ratio, only if each laying worker produce a small number of males and the difference of male progeny number among workers is not large. Worker reproduction could be an important cause of the generally lower genetic variation found in Hymenoptera, through its effect on Ne. PMID:22948186

  12. Male songbird indicates body size with low-pitched advertising songs.

    PubMed

    Hall, Michelle L; Kingma, Sjouke A; Peters, Anne

    2013-01-01

    Body size is a key sexually selected trait in many animal species. If size imposes a physical limit on the production of loud low-frequency sounds, then low-pitched vocalisations could act as reliable signals of body size. However, the central prediction of this hypothesis--that the pitch of vocalisations decreases with size among competing individuals--has limited support in songbirds. One reason could be that only the lowest-frequency components of vocalisations are constrained, and this may go unnoticed when vocal ranges are large. Additionally, the constraint may only be apparent in contexts when individuals are indeed advertising their size. Here we explicitly consider signal diversity and performance limits to demonstrate that body size limits song frequency in an advertising context in a songbird. We show that in purple-crowned fairy-wrens, Malurus coronatus coronatus, larger males sing lower-pitched low-frequency advertising songs. The lower frequency bound of all advertising song types also has a significant negative relationship with body size. However, the average frequency of all their advertising songs is unrelated to body size. This comparison of different approaches to the analysis demonstrates how a negative relationship between body size and song frequency can be obscured by failing to consider signal design and the concept of performance limits. Since these considerations will be important in any complex communication system, our results imply that body size constraints on low-frequency vocalisations could be more widespread than is currently recognised. PMID:23437221

  13. The Play Factor: Effect of Social Skills Group Play Therapy on Adolescent African-American Males

    ERIC Educational Resources Information Center

    Earls, Melissa K.

    2009-01-01

    The purpose of this study was to examine the effectiveness of Social Skills Group Play Therapy on remedying the social skills deficits of adolescent African-American males. Additionally, the study investigated whether age and grade level impacted the outcome of the intervention. The participants were adolescent African-American males ages 10 to…

  14. Wade's and Gelso's Contribution to the New Psychology of Men: Male Reference Group Dependence Theory.

    ERIC Educational Resources Information Center

    O'Neil, James M.

    1998-01-01

    Relates Wade's and Gelso's Male Reference Group Dependence Theory to past and present literature in the new psychology of men. Points out the strengths of the ideas and data; reflects on where the theory needs more clarification and extension. (MKA)

  15. Prediction of Self-Actualization in Male Participants in a Group Conducted by Female Leaders

    ERIC Educational Resources Information Center

    Follingstad, Diane R.; And Others

    1976-01-01

    Attempts to predict which male Ss (high or low authoritarian personality) would reflect higher self-actualization scores when exposed to a 16-hour marathon group conducted by female leaders. (Author/RK)

  16. Within-group social bonds in white-faced saki monkeys (Pithecia pithecia) display male-female pair preference.

    PubMed

    Thompson, Cynthia L; Norconk, Marilyn A

    2011-10-01

    White-faced saki monkeys (Pithecia pithecia) lack most of the behavioral and physical traits typical of primate monogamy [Fuentes, 1999]. In order to determine if social bonds in this species reflect patterns displayed by pair-bonded groups or larger multimale-multifemale groups, we draw on 17 months of data collected on wild white-faced sakis at Brownsberg Nature Park, Suriname. We analyzed within-group social bonds for three habituated groups (one two-adult and two multiadult groups) by measuring grooming, proximity, and approach/leave patterns between adult and subadult group members. We found that both two-adult and multiadult groups showed significantly stronger social bonds between a single male-female dyad within each group (deemed "primary dyads"). In all three groups, primary dyads were composed of the oldest adult male and a breeding female. These pairs had significantly higher levels of grooming than other within-group dyads and were also in close proximity (<1 m) more often than nonprimary dyads. Grooming in primary dyads was nonreciprocal, and consistently biased toward female investment. Grooming patterns in nonprimary dyads varied, but were often more reciprocal. Grooming and proximity of the primary dyad also changed in relation to infant development. Our results suggest that while white-faced sakis do not show behavioral and physical traits typical of monogamy or pair-bonding, social bonds are strongest between a single male-female pair. Pitheciine social systems range from small group monogamy in Callicebus to large multimale-multifemale groups in Chiropotes and Cacajao. As the middle taxon in this platyrrhine radiation, behavioral strategies of white-faced sakis provide a model for how social bonds and affiliation could be influenced by and affect the evolution of larger group size in primates. PMID:21695710

  17. Incidence of Tooth Size Discrepancy in Different Groups of Malocclusion and its Relation to Extraction

    PubMed Central

    Gaddam, Rajkumar; Arya, Siddarth; Shetty, K Sadashiva

    2015-01-01

    Background: For proper intercuspation, the teeth must be proportional in size. If teeth are mismatched, with unusually large teeth in one arch compared to the other, then an ideal occlusion cannot be attained. This study has been done to determine the prevalence of tooth size discrepancies among orthodontic patients in general and also between different malocclusion groups, sex, and to analyze the change in the degree of severity in Bolton discrepancy before and after the hypothetical premolar extraction. Methods: The study was carried out on randomly collected 100 pre-treatment dental casts. Tooth size analyses were performed on these pre-treatment models and Mesio distal tooth size ratios were measured as described by Bolton before and after various patterns of hypothetical extraction. Result: The results were statistically evaluated using ANOVA and paired samples t-test. 5 out of 100 patients are seen with severe Bolton discrepancy with Bolton values (BV) ranging above and below 2 standard deviation. Statistically insignificant difference is seen between males and females and also between various groups of malocclusion. The difference between the pre-treatment and post extraction BV was found statistically significant for the first premolar extraction and insignificant for others. Conclusion: The results of this study indicate a new point of view to the question of which teeth to extract when evaluated for tooth size aspect only. PMID:26225105

  18. Habitat patch size and mating system as determinants of social group size in coral-dwelling fishes

    NASA Astrophysics Data System (ADS)

    Thompson, V. J.; Munday, P. L.; Jones, G. P.

    2007-03-01

    It is thought that the size and dispersion of habitat patches can determine the size and composition of animal social groups, however, this has rarely been tested. The relationship between group size, the mating system, and habitat patch size in six species of coral-dwelling gobies was examined. For all species, there was a positive correlation between coral colony size and social group size, however the strength of this relationship varied among species. Paragobiodon xanthosomus exhibited the strongest relationship and a manipulative field experiment confirmed that coral colony size limited group size in this species. For other species including Paragobiodon melanosomus and Eviota bifasciata, either a highly conservative mating system ( P. melanosomus), or increased mobility ( E. bifasciata) appeared to disrupt the relationship between habitat patch size and group size. There was no consistent relationship between the mating system exhibited and group size among the species investigated. These results demonstrate that habitat patch size, mobility, and mating systems can interact in complex ways to structure group size even among closely related species.

  19. Reducing Alcohol Risk in Adjudicated Male College Students: Further Validation of a Group Motivational Enhancement Intervention

    ERIC Educational Resources Information Center

    LaBrie, Joseph W.; Cail, Jessica; Pedersen, Eric R.; Migliuri, Savannah

    2011-01-01

    This study examined the effectiveness of a single-session group motivational enhancement alcohol intervention on adjudicated male college students. Over two sequential academic years, 230 students sanctioned by the university for alcohol-related infractions attended a 60- to 75-minute group intervention. The intervention consisted of a timeline…

  20. Scale-Dependent Habitat Selection and Size-Based Dominance in Adult Male American Alligators.

    PubMed

    Strickland, Bradley A; Vilella, Francisco J; Belant, Jerrold L

    2016-01-01

    Habitat selection is an active behavioral process that may vary across spatial and temporal scales. Animals choose an area of primary utilization (i.e., home range) then make decisions focused on resource needs within patches. Dominance may affect the spatial distribution of conspecifics and concomitant habitat selection. Size-dependent social dominance hierarchies have been documented in captive alligators, but evidence is lacking from wild populations. We studied habitat selection for adult male American alligators (Alligator mississippiensis; n = 17) on the Pearl River in central Mississippi, USA, to test whether habitat selection was scale-dependent and individual resource selectivity was a function of conspecific body size. We used K-select analysis to quantify selection at the home range scale and patches within the home range to determine selection congruency and important habitat variables. In addition, we used linear models to determine if body size was related to selection patterns and strengths. Our results indicated habitat selection of adult male alligators was a scale-dependent process. Alligators demonstrated greater overall selection for habitat variables at the patch level and less at the home range level, suggesting resources may not be limited when selecting a home range for animals in our study area. Further, diurnal habitat selection patterns may depend on thermoregulatory needs. There was no relationship between resource selection or home range size and body size, suggesting size-dependent dominance hierarchies may not have influenced alligator resource selection or space use in our sample. Though apparent habitat suitability and low alligator density did not manifest in an observed dominance hierarchy, we hypothesize that a change in either could increase intraspecific interactions, facilitating a dominance hierarchy. Due to the broad and diverse ecological roles of alligators, understanding the factors that influence their social dominance

  1. Group size, individual role differentiation and effectiveness of cooperation in a homogeneous group of hunters

    PubMed Central

    Escobedo, R.; Muro, C.; Spector, L.; Coppinger, R. P.

    2014-01-01

    The emergence of cooperation in wolf-pack hunting is studied using a simple, homogeneous, particle-based computational model. Wolves and prey are modelled as particles that interact through attractive and repulsive forces. Realistic patterns of wolf aggregation readily emerge in numerical simulations, even though the model includes no explicit wolf–wolf attractive forces, showing that the form of cooperation needed for wolf-pack hunting can take place even among strangers. Simulations are used to obtain the stationary states and equilibria of the wolves and prey system and to characterize their stability. Different geometric configurations for different pack sizes arise. In small packs, the stable configuration is a regular polygon centred on the prey, while in large packs, individual behavioural differentiation occurs and induces the emergence of complex behavioural patterns between privileged positions. Stable configurations of large wolf-packs include travelling and rotating formations, periodic oscillatory behaviours and chaotic group behaviours. These findings suggest a possible mechanism by which larger pack sizes can trigger collective behaviours that lead to the reduction and loss of group hunting effectiveness, thus explaining the observed tendency of hunting success to peak at small pack sizes. They also explain how seemingly complex collective behaviours can emerge from simple rules, among agents that need not have significant cognitive skills or social organization. PMID:24694897

  2. Group size, individual role differentiation and effectiveness of cooperation in a homogeneous group of hunters.

    PubMed

    Escobedo, R; Muro, C; Spector, L; Coppinger, R P

    2014-06-01

    The emergence of cooperation in wolf-pack hunting is studied using a simple, homogeneous, particle-based computational model. Wolves and prey are modelled as particles that interact through attractive and repulsive forces. Realistic patterns of wolf aggregation readily emerge in numerical simulations, even though the model includes no explicit wolf-wolf attractive forces, showing that the form of cooperation needed for wolf-pack hunting can take place even among strangers. Simulations are used to obtain the stationary states and equilibria of the wolves and prey system and to characterize their stability. Different geometric configurations for different pack sizes arise. In small packs, the stable configuration is a regular polygon centred on the prey, while in large packs, individual behavioural differentiation occurs and induces the emergence of complex behavioural patterns between privileged positions. Stable configurations of large wolf-packs include travelling and rotating formations, periodic oscillatory behaviours and chaotic group behaviours. These findings suggest a possible mechanism by which larger pack sizes can trigger collective behaviours that lead to the reduction and loss of group hunting effectiveness, thus explaining the observed tendency of hunting success to peak at small pack sizes. They also explain how seemingly complex collective behaviours can emerge from simple rules, among agents that need not have significant cognitive skills or social organization. PMID:24694897

  3. Intraspecific variation in space use, group size, and mating systems of caviomorph rodents

    PubMed Central

    Maher, Christine R.; Burger, Joseph Robert

    2012-01-01

    Intraspecific variation in social systems is widely recognized across many taxa, and specific models, including polygamy potential, resource defense, and resource dispersion, have been developed to explain the relationship between ecological variation and social organization. Although mammals from temperate North America and Eurasia have provided many insights into this relationship, rodents from the Neotropics and temperate South America have largely been ignored. In this review we focus on reports documenting intraspecific variation in spacing systems, group size, and mating systems of caviomorphs. This large group of New World hystricognath rodents occupies a diverse array of habitats; thus, members of the same species potentially exhibit different social systems in response to different ecological conditions. Spatial patterns vary in response to a diverse array of factors, including predation, food availability, population density, and soil characteristics. Changes in group size typically correlate with changes in resource availability, particularly food. Mating systems generally reflect the ability of males to control access to females, which may depend on population density or food distribution. In general, social organization in caviomorphs fits predictions of resource-based models; however, most studies have been purely observational, involving small numbers of animals over short time periods and reporting qualitative rather than quantitative levels of ecological correlates. In future studies the use of molecular techniques and controlled, experimental manipulations can increase our understanding of intraspecific variation in caviomorph social systems. This understudied group of rodents offers excellent opportunities to provide insights into the influence of ecological conditions on behavior such as social systems. PMID:22328790

  4. Endogenous control of sexual size dimorphism: Gonadal androgens have neither direct nor indirect effect on male growth in a Madagascar ground gecko (Paroedura picta).

    PubMed

    Kubička, Lukáš; Starostová, Zuzana; Kratochvíl, Lukáš

    2015-12-01

    Changes in the effect of gonadal androgens on male growth are considered as a possible mechanism allowing shifts in magnitude and even direction of sexual size dimorphism in vertebrates, particularly squamate reptiles. Positive effects of gonadal androgens on male growth were found in several male-larger species of lizards. Contrastingly, we document that in the male-larger Madagascar ground gecko (Paroedura picta) gonadal androgens do not affect male growth under constant thermal conditions. However, the absence of a thermal gradient might prevent the potential indirect effect of gonadal androgens on growth via the influence of circulating hormones on an individual's thermoregulation and hence metabolic rate. In order to study this, we monitored the growth and body temperature of socially isolated sham-operated and castrated males of the same species in a thermal gradient. We also compared the oxygen consumption and activity between the treatment groups in the open field to test the effect of gonadal hormones on these traits potentially affecting growth. Even under a thermal gradient we found no effect of gonadal androgens on growth rate or final body dimensions. Castration also did not significantly affect oxygen consumption or activity in the open field test. Together with our previous findings, we can exclude both the direct effect of male gonadal androgens on the ontogeny of sexual size dimorphism via the influence on the growth axis, and the indirect influence of gonadal androgens acting on the ontogeny of SSD through the effect on thermoregulation, metabolic rate and activity. PMID:26431613

  5. Females allocate differentially to offspring size and number in response to male effects on female and offspring fitness.

    PubMed

    Kindsvater, Holly K; Alonzo, Suzanne H

    2014-03-22

    Female investment in offspring size and number has been observed to vary with the phenotype of their mate across diverse taxa. Recent theory motivated by these intriguing empirical patterns predicted both positive (differential allocation) and negative (reproductive compensation) effects of mating with a preferred male on female investment. These predictions, however, focused on total reproductive effort and did not distinguish between a response in offspring size and clutch size. Here, we model how specific paternal effects on fitness affect maternal allocation to offspring size and number. The specific mechanism by which males affect the fitness of females or their offspring determines whether and how females allocated differentially. Offspring size is predicted to increase when males benefit offspring survival, but decrease when males increase offspring growth rate. Clutch size is predicted to increase when males contribute to female resources (e.g. with a nuptial gift) and when males increase offspring growth rate. The predicted direction and magnitude of female responses vary with female age, but only when per-offspring paternal benefits decline with clutch size. We conclude that considering specific paternal effects on fitness in the context of maternal life-history trade-offs can help explain mixed empirical patterns of differential allocation and reproductive compensation. PMID:24478292

  6. Male secondary sexual structures and the systematics of the Thereus oppia species group (Lepidoptera, Lycaenidae, Eumaeini)

    PubMed Central

    Robbins, Robert K.; Heredia, María Dolores; Busby, Robert C.

    2015-01-01

    Abstract The Thereus oppia species group includes species with and without a scent pad, which is a histologically and morphologically characterized male secondary sexual structure on the dorsal surface of the forewing. To assess the hypothesis that these structures are lost evolutionarily, but not regained (Dollo’s Law), the taxonomy of this species group is revised. Thereus lomalarga sp. n., and Thereus brocki sp. n., are described. Diagnostic traits, especially male secondary structures, within the Thereus oppia species group are illustrated. Distributional and biological information is summarized for each species. Three species have been reared, and the caterpillars eat Loranthaceae. An inferred phylogeny is consistent with the hypothesis that scent pads in the Thereus oppia species group have been lost evolutionarily twice (in allopatry), and not re-gained. PMID:26448715

  7. Perceptions of Male and Female Dominant Behavior in Small Group Interactions.

    ERIC Educational Resources Information Center

    Bendelow, Mary Margaret

    A study was conducted to determine how males and females were perceived when using identical dominant behaviors. The subjects, 360 college students, viewed one of six stimulus drawings of groups of four seated people and indicated their attributions of dominant behavior on 22 bipolar perceptual scales. Analyses were conducted to create and compare…

  8. Employing a Group Medical Intervention for Hypertensive Male Veterans: An Exploratory Analysis

    ERIC Educational Resources Information Center

    Westheimer, Joshua M.; Capello, Jeremy; McCarthy, Christopher; Denny, Nathan

    2009-01-01

    Doctor Interactive Group Medical Appointments (DIGMAs) were conducted over a period of 7 months; 73 hypertensive male veterans were enrolled in the study and 58 completed it. Findings indicated that both systolic and diastolic blood pressure readings were significantly reduced from pretest to posttest. Participant self-report of health promoting…

  9. Reducing Depression, Anxiety, and Trauma of Male Inmates: An HIV/AIDS Psychoeducational Group Intervention.

    ERIC Educational Resources Information Center

    Pomeroy, Elizabeth C.; Kiam, Risa; Green, Diane L.

    2000-01-01

    Reports on a quasi-experimental research study that found that a 10-session psychoeducational group intervention was effective in increasing knowledge of AIDS and decreasing depression, anxiety, and trauma symptoms among male inmates. The intervention consisted of both AIDS education topics and psychological support. Results indicate significant…

  10. Early Childhood Teachers' Affectionate Behavior: Differential Expression to Female Children, Male Children, and Groups of Children.

    ERIC Educational Resources Information Center

    Botkin, Darla; Twardosz, Sandra

    Examined were differences in the amount of affectionate behavior early childhood teachers expressed to (1) individual children and groups of children, and (2) female and male children. Data were collected through naturalistic observations of 47 female teachers in six day care centers. Teachers' affectionate behaviors and the types of recipients…

  11. Metabolic Effects of Chronic Heavy Physical Training on Male Age Group Swimmers.

    ERIC Educational Resources Information Center

    Caffrey, Garret P.; And Others

    This study attempts to appraise the effectiveness of chronic heavy exercise on 13 male swimmers from 10 to 17 years of age. The experimental group trained six days a week, often with more than one workout per day. During this period, the principles of interval training were employed in conjunction with high-intensity swimming. At the completion of…

  12. No Effect of Social Group Composition or Size on Hippocampal Formation Morphology and Neurogenesis in Mountain Chickadees (Poecile gambeli)

    PubMed Central

    Fox, Rebecca A.; Roth, Timothy C.; LaDage, Lara D.; Pravosudov, Vladimir V.

    2010-01-01

    Brain plasticity and adult neurogenesis may play a role in many ecologically-important processes including mate recognition, song learning and production, and spatial memory processing. In a number of species, both physical and social environments appear to influence attributes (e.g., volume, neuron number, and neurogenesis) of particular brain regions. The hippocampus in particular is well known to be especially sensitive to such changes. Although social grouping in many taxa includes the formation of male and female pairs, most studies of the relationship between social environment and the hippocampus have typically considered only solitary animals and those living in same-sex groups. Thus, the aim of the present study was to compare the volume of the hippocampal formation, the total number of hippocampal neurons, and the number of immature neurons in the hippocampus (as determined by doublecortin expression) in mountain chickadees (Poecile gambeli) housed in groups of males and females, male-female pairs, same-sex pairs of either males or females, and as solitary individuals. The different groups were visually and physically, but not acoustically, isolated from each other. We found no significant differences between any of our groups in hippocampal volume, the total number of hippocampal neurons, or the number of immature neurons. Our results thus provided no support to the hypothesis that social group composition and/or size have an effect on hippocampal morphology and neurogenesis. PMID:20336697

  13. Urinary C-peptide levels in male bonobos (Pan paniscus) are related to party size and rank but not to mate competition.

    PubMed

    Surbeck, Martin; Deschner, Tobias; Behringer, Verena; Hohmann, Gottfried

    2015-05-01

    Within- and between-species variation in male mating strategies has been attributed to a multitude of factors including male competitive ability and the distribution of fertile females across space and time. Differences in energy balance across and within males allow for the identification of some of the trade-offs associated with certain social and mating strategies. Bonobos live in groups with a high degree of fission-fusion dynamics, there is co-dominance between the sexes and a linear dominance hierarchy among males. Males compete over access to females, breeding is aseasonal, and females exhibit sexual swellings over extended time periods. In this study we use urinary C-peptide (UCP) levels in male bonobos (Pan paniscus) obtained from 260 urine samples from a wild bonobo community, to quantify male energy balance during mate competition and levels of gregariousness in the species. Although high ranking males are more aggressive, spend more time in proximity to maximally tumescent females, and have higher mating frequencies, we found no indication that mate guarding or mate competition affected male energy balance. Our results showed a positive correlation between monthly mean UCP levels and mean party size. When traveling in large parties, high ranking males had higher UCP levels than those of the low ranking males. These results support the hypothesis that patterns of fission-fusion dynamics in bonobos are either linked to energy availability in the environment or to the energetic costs of foraging. The finding of a rank-bias in UCP levels in larger parties could also reflect an increase in contest competition among males over access to food. PMID:25870021

  14. Subordinate male meerkats prospect for extra-group paternity: alternative reproductive tactics in a cooperative mammal.

    PubMed

    Young, Andrew J; Spong, Goran; Clutton-Brock, Tim

    2007-07-01

    In cooperatively breeding species, subordinates typically suffer strong constraints on within-group reproduction. While numerous studies have highlighted the additional fitness benefits that subordinates might accrue through helping, few have considered the possibility that subordinates may also seek extra-group matings to improve their chances of actually breeding. Here, we show that subordinate males in cooperative meerkat, Suricata suricatta, societies conduct frequent extraterritorial forays, during periods of peak female fertility, which give rise to matings with females in other groups. Genetic analyses reveal that extra-group paternity (EGP) accrued while prospecting contributes substantially to the reproductive success of subordinates: yielding the majority of their offspring (approx. 70%); significantly reducing their age at first reproduction and allowing them to breed without dispersing. We estimate that prospecting subordinates sire 20-25% of all young in the population. While recent studies on cooperative birds indicate that dominant males accrue the majority of EGP, our findings reveal that EGP can also arise from alternative reproductive tactics employed exclusively by subordinates. It is important, therefore, that future attempts to estimate the fitness of subordinate males in animal societies quantify the distribution of extra-group as well as within-group paternity, because a substantial proportion of the reproductive success of subordinates may otherwise go undetected. PMID:17456454

  15. Mating system and size advantage of male mating in the protogynous swamp eel Monopterus albus with paternal care.

    PubMed

    Matsumoto, Seiji; Takeyama, Tomohiro; Ohnishi, Nobuhiro; Kohda, Masanori

    2011-05-01

    In fish with paternal care, protogynous sex change (female to male) is rare and has only been reported from species with haremic polygyny. The swamp eel, Monopterus albus, is a protogynous fish with paternal care, but little is known about its mating system. To understand protogyny in this species, we examined the mating system and male size advantage in mating in M. albus under semi-natural condition. Females swam over wide ranges and visited multiple male nests. Males defended a narrow territory around nests against other males that approached nests; at these nests, males courted and accepted visiting females. After spawning inside nests, caring males continued to perform courtship activities, and multiple breeding was observed. These observations suggest that the M. albus mating system is male-territory-visiting (MTV)-polygamy. Larger males had nests, and mated more frequently compared with small males. Because small initial males of this species are not found in nature, and because M. albus does not engage in sneaking tactics, larger nesting males do not suffer from reproductive parasitism. Thus, protogyny in this fish is likely consistent with the predictions of the size-advantage model. Biting attacks by territorial males of this predatory fish seriously wounded intruding males, occasionally resulting in the death of the intruder. We discuss the possibility that sexual differences in mortality rates in small fish may facilitate the evolution of protogyny in this species. Protogyny of the swamp eel is, to our knowledge, the first example of an MTV-polygamous mating system in a fish with paternal care. PMID:21557660

  16. Ozone inhalation effects in females varying widely in lung size: Comparison with males

    SciTech Connect

    Messineo, T.D.; Adams, W.C. )

    1990-07-01

    It has been suggested that lung size accounts for observed gender differences in responsiveness to the same total inhaled dose of O3. To test the hypothesis that lung size is a determinant of magnitude of response within a gender, two groups of 14 healthy young adult females differing significantly in forced vital capacity (FVC; i.e., small-lung group mean = 3.74 liters (range 3.2-4.0) and large-lung group mean = 5.11 liters (range 4.5-6.2)) were exposed for 1 h to filtered air (FA) and to 0.18 and 0.30 ppm O3. On each occasion, subjects exercised continuously on a cycle ergometer at a work rate that elicited a mean minute ventilation of approximately 47 l/min. For the small-lung group (mean total lung capacity (TLC) = 4.52 liters) exercise O2 uptake was 67% of maximal O2 uptake (VO2max), and that for the large-lung group (TLC 6.37 liters) was 61% of VO2max. Statistical analysis revealed significant decrements for both groups in FVC, forced expiratory volume in 1 s (FEV1.0), and forced expiratory flow rate in the middle half of FVC on exposure to 0.18 and 0.30 ppm O3. Exercise respiratory frequency increased, and tidal volume decreased significantly in both groups in response to 0.18 and 0.30 ppm O3 exposure. On exposure to 0.30 ppm O3, the number of individual subjective symptoms reported and their severity were significantly greater for both groups than those reported for the FA and 0.18 ppm O3 exposures. Both groups evidenced similar percent changes in pulmonary function and exercise ventilation response, and in subjective symptom response.

  17. Core groups and the transmission of HIV: learning from male sex workers.

    PubMed

    Parker, Melissa

    2006-01-01

    A growing and substantial body of research suggests that female sex workers play a disproportionately large role in the transmission of HIV in many parts of the world, and they are often referred to as core groups by epidemiologists, mathematical modellers, clinicians and policymakers. Male sex workers, by contrast, have received little attention and it is not known whether it is helpful to conceptualize them as a core group. This paper draws upon ethnographic research documenting social and sexual networks in London and looks at the position of five male sex workers within a network comprising 193 men and seven women (as well as 1378 anonymous sexual contacts and 780 commercial contacts). In so doing, it suggests that there is no evidence to show that male sex workers are more or less likely to acquire or transmit HIV in the course of commercial sex compared with other types of sexual relationships. In addition, men engaging in non-commercial sex all reported having unprotected sex in a variety of contexts and relationships and there is no evidence to suggest that men who are not sex workers play less of a role in the transmission of HIV. In short, these data suggest that it would be inappropriate to conceptualize male sex workers as a core group. This is not to suggest that public policy should continue to overlook male sex workers. New and inventive approaches are required to reach out to a vulnerable but diverse group of men, selling sex for a variety of reasons; even if these men are no more vulnerable to acquiring and/or transmitting HIV than other men and women that form part of their network. PMID:16321168

  18. Investigating Male Tobacco Use and Expenditure Patterns across Socio-Economic Groups in Nigeria

    PubMed Central

    Uguru, Nkoli P.; Mbachu, Chinyere; Ibe, Ogochukwu P.; Uguru, Chibuzo C.; Odukoya, Oluwakemi; Okwuosa, Chinenye; Onwujekwe, Obinna

    2015-01-01

    The magnitude of variation in economic costs of tobacco consumption among socio-economic status (SES) groups in Nigeria is unclear. Understanding the factors that influence tobacco use and expenditure among different socio-economic groups would inform decisions on interventions for tobacco control in Nigeria. Secondary data was obtained from the 2008 National demographic and health survey. Information on tobacco use and expenditure in households and individual males were extracted from the database. A total of 34,070 households and 15,846 individual males were sampled. Analysis was done using descriptive statistics and binary logistic regression analysis. Information on wealth index obtained were categorized into socio-economic quintile groups (Q1 to Q5), representing poorest to richest socio-economic groups. To estimate expenditure on cigarettes, the average cost of a stick of cigarette was obtained and multiplied with the number of sticks smoked per day. The proportion of households that use tobacco in Nigeria is 5.25% with a greater percentage (89.6%) residing in the rural areas. Prevalence of cigarette smoking in individual males is 8.59%, and the poorer SES group smoked more cigarettes (20.9%) and spent more (0.60–1.19USD) than the richest SES group. Low education level, traditional beliefs, literacy levels, SES and employment status all influence cigarette smoking in adult males. Although poor people smoked more and spent more of their income on cigarettes, other factors like educational level and traditional beliefs were found to influence practice of cigarette smoking in men. This implies that tobacco control legislation through increased taxes alone may not effectively reduce the use of tobacco and its products in Nigeria. A consolidated approach that includes behavioral change procedures, enforcing bans on tobacco advertisement and the use of strong graphic anti-tobacco messages targeted at both the poor and rich as well as the educated and uneducated

  19. 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

  20. Antagonistic pre- and post-copulatory sexual selection on male body size in a water strider (Gerris lacustris).

    PubMed Central

    Danielsson, I

    2001-01-01

    A crucial question in sexual selection theory is whether post-copulatory sexual selection reinforces or counteracts conventional pre-copulatory sexual selection. Male body size is one of the traits most generally favoured by pre-copulatory sexual selection; and recent studies of sperm competition often suggest that large male size is also favoured by post-copulatory sexual selection. In contrast to this general pattern, this study shows that pre- and post-copulatory sexual selection act antagonistically on male body size in Gerris lacustris. One large and one small male were kept together with two females in this experiment. Large males had a significant mating advantage, but small males copulated longer and gained higher fertilization success from each mating. Large and small males, however, gained similar reproductive success, and there was no overall correlation between mating success and reproductive success. These results suggest that estimates of male fitness based solely on mating success should be viewed with caution, because of potentially counteracting post-copulatory selection. PMID:12123301

  1. Evaluation of Mid-Size Male Hybrid III Models for use in Spaceflight Occupant Protection Analysis

    NASA Technical Reports Server (NTRS)

    Putnam, Jacob B.; Sommers, Jeffrey T.; Wells, Jessica A.; Newby, Nathaniel J.; Currie-Gregg, Nancy J.; Lawrence, Chuck

    2016-01-01

    In an effort to improve occupant safety during dynamic phases of spaceflight, the National Aeronautics and Space Administration (NASA) has worked to develop occupant protection standards for future crewed spacecraft. One key aspect of these standards is the identification of injury mechanisms through anthropometric test devices (ATDs). Within this analysis, both physical and computational ATD evaluations are required to reasonably encompass the vast range of loading conditions any spaceflight crew may encounter. In this study the accuracy of publically available mid-size male HIII ATD finite element (FE) models are evaluated within applicable loading conditions against extensive sled testing performed on their physical counterparts. Methods: A series of sled tests were performed at the Wright Patterson Air force Base (WPAFB) employing variations of magnitude, duration, and impact direction to encompass the dynamic loading range for expected spaceflight. FE simulations were developed to the specifications of the test setup and driven using measured acceleration profiles. Both fast and detailed FE models of the mid-size male HIII were ran to quantify differences in their accuracy and thus assess the applicability of each within this field. Results: Preliminary results identify the dependence of model accuracy on loading direction, magnitude, and rate. Additionally the accuracy of individual response metrics are shown to vary across each model within evaluated test conditions. Causes for model inaccuracy are identified based on the observed relationships. Discussion: Computational modeling provides an essential component to ATD injury metric evaluation used to ensure the safety of future spaceflight occupants. The assessment of current ATD models lays the groundwork for how these models can be used appropriately in the future. Identification of limitations and possible paths for improvement aid in the development of these effective analysis tools.

  2. Dietary intakes and food use of groups of elite Australian male athletes.

    PubMed

    Burke, L M; Gollan, R A; Read, R S

    1991-12-01

    The present study conducted dietary surveys of four groups of Australian male athletes: triathletes, marathon runners, Australian Rules football players, and Olympic weightlifters. Their training diets were assessed via a 7-day food record from which mean daily intakes of energy, macronutrients, and key micronutrients were estimated. The data were compared between groups as well as to recommendations in the literature for athlete nutrition. Results showed major differences between groups. The contribution of carbohydrate to total energy intake was greater for triathletes and marathon runners than for the other two groups. There was no difference between all four groups in the total amount of fat consumed, yet its contribution to total energy intake was significantly lower for triathletes and marathon runners. The football players and weightlifters consumed a similar fat:energy ratio as the typical Australian diet. Furthermore, the micronutrient density of the football players' diets was significantly lower than that of the other groups. PMID:1844570

  3. Salmon calcitonin reduces food intake through changes in meal sizes in male rhesus monkeys

    PubMed Central

    Bello, Nicholas T.; Kemm, Matthew H.; Moran, Timothy H.

    2008-01-01

    Amylinergic mechanisms are believed to be involved in the control of appetite. This study examined the effects of the amylin agonist, salmon calcitonin, on food intake and meal patterns in adult male rhesus monkeys. Fifteen minutes before the onset of their 6-h daily feeding period, monkeys received intramuscular injections of various doses of salmon calcitonin (0.032, 0.056, 0.1, 0.32, and 1 μg/kg) or saline. Salmon calcitonin dose dependently reduced total daily and hourly food intake, with significant decreases at the 0.1, 0.32, and 1 μg/kg doses. Daily food intake was reduced by ∼35%, 62%, and 96%, at these doses, respectively. An analysis of meal patterns revealed that size of the first meal was significantly reduced across the dose range of 0.056 to 1 μg/kg, while average meal size was reduced with the 0.32 and 1 μg/kg doses. Meal number was only affected at the 1 μg/kg dose. Repeated 5-day administration of the 0.1 μg/kg dose resulted in a reduction in daily food intake only on injection day 2, while significant reductions in food intake were observed on all five injection days with a 0.32 μg/kg dose. Daily food intake was also reduced for 1 day after the termination of the 5-day injections of the 0.32 μg/kg salmon calcitonin dose. These sustained reductions in intake were expressed through decreases in meal size. These data demonstrate that salmon calcitonin acutely and consistently decreases food intake mainly through reductions in meal sizes in nonhuman primates. PMID:18480241

  4. Salmon calcitonin reduces food intake through changes in meal sizes in male rhesus monkeys.

    PubMed

    Bello, Nicholas T; Kemm, Matthew H; Moran, Timothy H

    2008-07-01

    Amylinergic mechanisms are believed to be involved in the control of appetite. This study examined the effects of the amylin agonist, salmon calcitonin, on food intake and meal patterns in adult male rhesus monkeys. Fifteen minutes before the onset of their 6-h daily feeding period, monkeys received intramuscular injections of various doses of salmon calcitonin (0.032, 0.056, 0.1, 0.32, and 1 microg/kg) or saline. Salmon calcitonin dose dependently reduced total daily and hourly food intake, with significant decreases at the 0.1, 0.32, and 1 microg/kg doses. Daily food intake was reduced by approximately 35%, 62%, and 96%, at these doses, respectively. An analysis of meal patterns revealed that size of the first meal was significantly reduced across the dose range of 0.056 to 1 microg/kg, while average meal size was reduced with the 0.32 and 1 microg/kg doses. Meal number was only affected at the 1 microg/kg dose. Repeated 5-day administration of the 0.1 microg/kg dose resulted in a reduction in daily food intake only on injection day 2, while significant reductions in food intake were observed on all five injection days with a 0.32 microg/kg dose. Daily food intake was also reduced for 1 day after the termination of the 5-day injections of the 0.32 microg/kg salmon calcitonin dose. These sustained reductions in intake were expressed through decreases in meal size. These data demonstrate that salmon calcitonin acutely and consistently decreases food intake mainly through reductions in meal sizes in nonhuman primates. PMID:18480241

  5. Do male secondary sexual characters correlate with testis size and sperm length in the small hairy maggot blowfly?

    PubMed

    Jones, Stephanie D; Wallman, James F; Byrne, Phillip G

    2015-12-01

    The phenotype-linked fertility hypothesis proposes that secondary sexual characters (SSCs) advertise a male's fertility to prospective mates. However, findings from empirical studies attempting to test this hypothesis are often ambivalent or even contradictory, and few studies have simultaneously evaluated how both morphological and behavioural SSCs relate to ejaculate characteristics. Males of the small hairy maggot blowfly, Chrysomya varipes, possess conspicuous foreleg ornaments and display highly stereotyped courtship behaviour. These traits are favoured by females during pre-copulatory mate choice, but it remains unknown whether they correlate with post-copulatory traits expected to influence male fertility. The aim of this study was to investigate whether male courtship and ornamentation correlate with testis size and sperm length in C. varipes. We found that males investing more in courtship had bigger testes, and males with more extensive foreleg ornamentation released sperm with longer tails. Based on the assumption that larger testes enable males to produce more sperm, and that sperm with longer tails have greater propulsive force, our findings suggest that more vigorous and more ornamented males may be more fertile. These findings lend support to the phenotype-linked fertility hypothesis. However, a complete test of this hypothesis will require evaluating whether testis size and sperm length influence male fertilisation ability, as well as female fecundity and/or fertility. PMID:26297128

  6. Welfare of entire male pigs is improved by socialising piglets and keeping intact groups until slaughter.

    PubMed

    Rydhmer, L; Hansson, M; Lundström, K; Brunius, C; Andersson, K

    2013-09-01

    In today's production systems, pigs raised for slaughter are mixed many times, resulting in stress and fighting. The negative consequences of mixing are probably more severe with entire males than with castrates, as they fight more. In this project, we studied a system without castration where entire male pigs met unfamiliar pigs only once. Piglets from two litters were allowed to visit each other from circa 2 weeks of age through an opening between the farrowing pens. Entire males from these litters were kept in intact groups from weaning and onwards, and they were slaughtered pen-wise in intact groups. Control pigs were raised and weaned in their litters and mixed with unknown pigs when moved to the growing-finishing unit. They were slaughtered by split marketing based on individual weight. In total, 96 entire males from 24 litters were studied. Activity and social interactions of pigs were studied by direct observations on three observation occasions per pen for pigs kept in intact groups and four occasions for control pigs. All pigs were inspected for skin lesions during raising and at slaughter. Results showed that fewer pigs in intact groups were resting (17.1% v. 28.5%; P = 0.044) and they showed less aggressive behaviour (16.1 v. 27.7 number of interactions per hour; P = 0.001) than control pigs when moved to the growing-finishing unit. They also got fewer skin lesions compared with control pigs (15 v. 35; P < 0.001). Consequently, control pigs tended to grow slower during the 1st week after mixing; however, growth rate during the whole growing-finishing phase did not differ between treatments (P = 0.205). Control pigs directed more aggressive behaviour towards non-litter mates than towards litter mates during the whole growing-finishing phase, whereas pigs from the other treatment made no difference between litter mates and other familiar pigs. At 67 kg, there was more sexual behaviour (mounting) among control pigs (7.6 v. 3.4; P = 0.033), but after

  7. Personality and subjective well-being in captive male western lowland gorillas living in bachelor groups.

    PubMed

    Schaefer, Sarah A; Steklis, H Dieter

    2014-09-01

    The purpose of this study was to determine the personality structure of eight male gorillas (five silverbacks and three blackbacks) housed at the Sedgwick County Zoo in Wichita, Kansas and to determine if personality predicts behavior and subjective well-being in male gorillas living in bachelor groups. We used the Hominoid Personality Questionnaire which contains 54 descriptive adjectives with representative items from the human five-factor model. Rates of 12 behaviors that are broadly defined as agonistic or affiliative were independently recorded and calculated. Principal components analysis yielded three reliable personality factors: Dominance, Extraversion/Agreeableness, and Conscientiousness. These results are the first potential quantitative evidence for a Conscientiousness factor in a hominoid other than chimpanzees and humans. This suggests that Conscientiousness originated with the common ancestor of male gorillas and humans around 10 million years ago. These results indicate that humans can reliably assess the personality and subjective well-being of captive male gorillas living in bachelor groups with robust levels of inter-rater reliability and validity. Furthermore, personality can accurately predict behavior (r = 0.79; n = 13) and subjective well-being (r = 0.83; n = 5) in gorillas and provide convergent and discriminant validity for the personality factors. The results advocate for the use of personality questionnaires in the captive management of bachelor gorillas over long-term multi-institutional behavioral studies. PMID:24677279

  8. Finisher and performance trends in female and male mountain ultramarathoners by age group

    PubMed Central

    Rüst, Christoph Alexander; Knechtle, Beat; Eichenberger, Evelyn; Rosemann, Thomas; Lepers, Romuald

    2013-01-01

    Background This study examined changes according to age group in the number of finishers and running times for athletes in female and male mountain ultramarathoners competing in the 78 km Swiss Alpine Marathon, the largest mountain ultramarathon in Europe and held in high alpine terrain. Methods The association between age and performance was investigated using analysis of variance and both single and multilevel regression analyses. Results Between 1998 and 2011, a total of 1,781 women and 12,198 men finished the Swiss Alpine Marathon. The number of female finishers increased (r2 = 0.64, P = 0.001), whereas the number of male finishers (r2 = 0.18, P = 0.15) showed no change. The annual top ten men became older and slower, whereas the annual top ten women became older but not slower. Regarding the number of finishers in the age groups, the number of female finishers decreased in the age group 18–24 years, whereas the number of finishers increased in the age groups 30–34, 40–44, 45–49, 50–54, 55–59, 60–64, and 70–74 years. In the age groups 25–29 and 35–39 years, the number of finishers showed no changes across the years. In the age group 70–74 years, the increase in number of finishers was linear. For all other age groups, the increase was exponential. For men, the number of finishers decreased in the age groups 18–24, 25–29, 30–34, and 35–39 years. In the age groups 40–44, 45–49, 50–54, 55–59, 60–64, 70–74, and 75–79 years, the number of finishers increased. In the age group 40–44 years, the increase was linear. For all other age groups, the increase was exponential. Female finishers in the age group 40–44 years became faster over time. For men, finishers in the age groups 18–24, 25–29, 30–34, 40–44, and 45–49 years became slower. Conclusion The number of women older than 30 years and men older than 40 years increased in the Swiss Alpine Marathon. Performance improved in women aged 40–44 years but

  9. Perception of Groups, Size of Opposition, and Social Influence

    ERIC Educational Resources Information Center

    Wilder, David A.

    1977-01-01

    Two experiments investigated the relationship between social influence and the number of persons attempting influence. Findings suggest that the manner in which persons are initially organized into groups and aggregates of individuals affects their persuasive impact on observers. (Editor/RK)

  10. Development of an online database of typical food portion sizes in Irish population groups.

    PubMed

    Lyons, Jacqueline; Walton, Janette; Flynn, Albert

    2013-01-01

    The Irish Food Portion Sizes Database (available at www.iuna.net) describes typical portion weights for an extensive range of foods and beverages for Irish children, adolescents and adults. The present paper describes the methodologies used to develop the database and some key characteristics of the portion weight data contained therein. The data are derived from three large, cross-sectional food consumption surveys carried out in Ireland over the last decade: the National Children's Food Survey (2003-2004), National Teens' Food Survey (2005-2006) and National Adult Nutrition Survey (2008-2010). Median, 25th and 75th percentile portion weights are described for a total of 545 items across the three survey groups, split by age group or sex as appropriate. The typical (median) portion weights reported for adolescents and adults are similar for many foods, while those reported for children are notably smaller. Adolescent and adult males generally consume larger portions than their female counterparts, though similar portion weights may be consumed where foods are packaged in unit amounts (for example, pots of yoghurt). The inclusion of energy under-reporters makes little difference to the estimation of typical portion weights in adults. The data have wide-ranging applications in dietary assessment and food labelling, and will serve as a useful reference against which to compare future portion size data from the Irish population. The present paper provides a useful context for researchers and others wishing to use the Irish Food Portion Sizes Database, and may guide researchers in other countries in establishing similar databases of their own. PMID:25191574

  11. Focus Groups Reveal Differences in Career Experiences Between Male and Female Geoscientists

    NASA Astrophysics Data System (ADS)

    Oconnell, S.; Frey, C. D.; Holmes, M.

    2003-12-01

    We conducted twelve telephone focus groups of geoscientists to discover what motivates geoscientists to enter our field and stay in our field. There were separate male and female groups from six different professional categories: administrators, full and associate professors, non-tenure track personnel, assistant professors, post-docs and PhD candidates, Bachelor's and Master's candidates. A total of 96 geoscientists participated. Specifically, respondents were asked what initially brought them into the geosciences. Three dominant themes emerged: the subject matter itself, undergraduate experiences, and relationships. A total of 51 responses to this question related to the subject matter itself. Approximately 61 percent (31) of those responses were given by male focus group participants. Across all focus groups, participants brought up issues such as a general appreciation of the outdoors, weather, rocks, and dinosaurs. Following closely behind the general subject matter is undergraduate events. Fifty-one responses mentioned something about undergraduate experiences such as an introductory class, a laboratory experience, or field experiences. While both female and male participants discussed the role of interpersonal relationships in their decision to become a geoscientist, females were slightly more likely to bring up relevant relationships (26 times for females compared to 21 for males). These relationships varied in both groups from a parent or grandparents influence to camping trips with professors. When respondents were asked whether they had ever considered leaving the geosciences and under what circumstances, there was a striking difference between males and females: males were far less likely to have ever considered leaving. Younger males were more likely to consider leaving than older geoscientists. They feel challenged by the financial constraints of graduate school and the time constraints of academic vs. family life. Many females considered leaving at

  12. Expression of group III metabotropic glutamate receptors in the reproductive system of male mice.

    PubMed

    Marciniak, Marcin; Chruścicka, Barbara; Lech, Tomasz; Burnat, Grzegorz; Pilc, Andrzej

    2016-03-01

    Although the presence of metabotropic glutamate (mGlu) receptors in the central nervous system is well documented, they have recently been found in peripheral and non-neuronal tissues. In the present study we investigated the expression of group III mGlu receptors in the reproductive system of male mice. Reverse transcription-polymerase chain reaction analysis revealed the presence of mGlu6, mGlu7 and mGlu8 (but not mGlu4) receptor transcripts in testes and epididymides from adult mice. In addition, expression of mGlu6 (Grm6) and mGlu8 receptor (Grm8) mRNA was detected in spermatozoa isolated from the vas deferens. The vas deferens was found to contain only mGlu7 receptor (Grm7) mRNA, which was particularly intense in 21-day-old male mice. In penile homogenates, only the mGlu7 receptor signal was detected. Genetic ablation of the mGlu7 receptor in males led to fertility disorders manifested by decreased insemination capability as well as deterioration of sperm parameters, particularly sperm motility, vitality, sperm membrane integrity and morphology, with a simultaneous increase in sperm concentration. These results indicate that constitutively expressed mGlu receptors in the male reproductive system may play an important role in ejaculation and/or erection processes, as well as in the formation and maturation of spermatozoa. PMID:25066043

  13. Male wing color properties predict the size of nuptial gifts given during mating in the Pipevine Swallowtail butterfly ( Battus philenor)

    NASA Astrophysics Data System (ADS)

    Rajyaguru, Parth K.; Pegram, Kimberly V.; Kingston, Alexandra C. N.; Rutowski, Ronald L.

    2013-06-01

    In many animals, males bear bright ornamental color patches that may signal both the direct and indirect benefits that a female might accrue from mating with him. Here we test whether male coloration in the Pipevine Swallowtail butterfly, Battus philenor, predicts two potential direct benefits for females: brief copulation duration and the quantity of materials the male passes to the female during mating. In this species, males have a bright iridescent blue field on the dorsal hindwing surface, while females have little or no dorsal iridescence. Females preferentially mate with males who display a bright and highly chromatic blue field on their dorsal hindwing. In this study, we show that the chroma of the blue field on the male dorsal hindwing and male body size (forewing length) significantly predict the mass of material or spermatophore that a male forms within the female's copulatory sac during mating. We also found that spermatophore mass correlated negatively with copulation duration, but that color variables did not significantly predict this potential direct benefit. These results suggest that females may enhance the material benefits they receive during mating by mating with males based on the coloration of their dorsal hindwing.

  14. A Sex-Linked Gene Controlling the Onset of Sexual Maturity in Female and Male Platyfish (XIPHOPHORUS MACULATUS), Fecundity in Females and Adult Size in Males

    PubMed Central

    Kallman, Klaus D.; Borkoski, Valerie

    1978-01-01

    A sex-linked gene, P, controls the onset of sexual maturity in the platyfish, Xiphophorus maculatus. The activity of this gene is correlated with the age and size at which the gonadotropic zone of the adenohypophysis differentiates and becomes physiologically active. Immature fish of all genotypes grow at the same rate; however, as adults, males with "early" genotypes are significantly smaller than males of "late" genotypes, since growth rate declines strongly under the influence of androgenic hormone. Five alleles, P1... P5, have been identified from natural populations that under controlled conditions cause gonad maturation between eight and 73 weeks. P1P1 males become mature at eight weeks and 21 mm, P2P2 and P3P3 males between eleven and 13.5 weeks and 25 to 29 mm, and P4P4 males at 25 weeks and 37 mm. Since P5 is X-linked, no males homozygous for P5 could be produced. The difference between P2 and P3 is largely based upon their interaction with P5. P3P5 males mature at 17.5 weeks and 33.5 mm and P2P5 males at 28 weeks and 38 mm. The rate of transformation of the unmodified anal fin into a gonopodium, which is under androgenic control, is directly related to the age at initiation of sexual maturity, ranging from 3.2 weeks in P1P1 males to seven weeks in P2P 5 males. These differences may reflect different levels of circulating gonadotropic and androgenic hormones.—In two genotypes of females, initiation of vitellogenesis was closely correlated with size and this critical size was independent of age (e.g., 21 mm for P1P1 ). In a third genotype (P1P5) the minimum size for vitellogenesis decreased with increasing age, so that females would mature as early as eleven weeks, provided they had attained at least 29 mm, but at 25 weeks even females as small as 23 mm possessed ripe gonads. For P5P5 females, which become mature between 34 and 73 weeks of age, there is no correlation between size and initiation of vitellogenesis. In all four genotypes of females examined

  15. Effect of group size and maize silage dietary levels on behaviour, health, carcass and meat quality of Mediterranean buffaloes.

    PubMed

    Masucci, F; De Rosa, G; Barone, C M A; Napolitano, F; Grasso, F; Uzun, P; Di Francia, A

    2016-03-01

    The effects of different dietary levels of maize silage (10% v. 36% DM) and group size (7 v. 14 animals) were assessed on growth performance and in vivo digestibility of 28 male fattening buffaloes. In addition, the effects of diet on meat quality and group size on behaviour and immune response were separately evaluated. Animals were weighed and assigned to three groups. The high silage - low size group (HL) was fed a total mixed ration (TMR) containing 36% DM of maize silage and consisted of seven animals (age 12.7±2.6 months; BW 382.2±67.7 kg at the start of the study). The low silage - low size group (LL) was fed a TMR containing 10% DM of maize silage and consisted of seven animals (age 13.0±2.7 months; BW 389.4±72.3 kg). The high silage - high size group (HH) was fed the 36% maize silage DM diet and consisted of 14 animals (age 13.9±3.25 months; BW 416.5±73.9 kg). Total space allowance (3.2 indoor+3.2 outdoor m2/animal) was kept constant in the three groups, as well as the ratio of animals to drinkers (seven animals per water bowl) and the manger space (70 cm per animal). Growth performance, carcass characteristics and digestibility were influenced neither by dietary treatment nor by group size, even if the group fed 36% maize silage diet showed a higher fibre digestibility. No effect of diet was found on meat quality. Group size did not affect the behavioural activities with the exception of drinking (1.04±0.35% v. 2.60±0.35%; P<0.01 for groups HL and HH, respectively) and vigilance (2.58±0.46% v. 1.20±0.46%; P<0.05 for groups HL and HH, respectively). Immune responses were not affected by group size. PMID:26549768

  16. Testosterone replacement alters the cell size in visceral fat but not in subcutaneous fat in hypogonadal aged male rats as a late-onset hypogonadism animal model

    PubMed Central

    Abdelhamed, Amr; Hisasue, Shin-ichi; Shirai, Masato; Matsushita, Kazuhito; Wakumoto, Yoshiaki; Tsujimura, Akira; Tsukamoto, Taiji; Horie, Shigeo

    2015-01-01

    Background Patients with late-onset hypogonadism (LOH) benefit from testosterone replacement by improvement in the parameters of the metabolic syndrome, but fat cell morphology in these patients is still unclear. This study aims to determine the effect of testosterone replacement on the morphology of fat cells in subcutaneous and visceral adipose tissue and on erectile function in hypogonadal aged male rats as a model of LOH. Methods Ten male Sprague-Dawley rats aged 20–22 months were randomly allocated to two groups, ie, aged male controls (control group, n=5) and aged males treated with testosterone replacement therapy (TRT group, n=5). Testosterone enanthate 25 mg was injected subcutaneously every 2 weeks for 6 weeks. At 6 weeks, the intracavernous pressure (ICP) and mean arterial blood pressure (MAP) ratio was assessed. Visceral and subcutaneous adipose tissue specimens were collected and analyzed using Image-J software. Results Body weight at 2, 4, and 6 weeks after TRT was 800.0±35.4 g, 767.5±46.3 g, and 780±40.4 g, respectively (not statistically significant). The ICP/MAP ratio was 0.341±0.015 in the TRT group and 0.274±0.049 in the control group (not statistically significant). The median subcutaneous fat cell size was 4.85×103 (range 0.85–12.53×103) μm2 in the control group and 4.93×103 (range 6.42–19.7×103) μm2 in the TRT group (not statistically significant). In contrast, median visceral fat cell size was significantly smaller in the TRT group (4.93×103 μm2 [range 0.51–14.88×103]) than in the control group (6.08×103 μm2 [0.77–19.97×103]; P<0.001, Mann-Whitney U test). Conclusion This is the first study clearly indicating that TRT can decrease visceral fat cell size, which is a key modulator in the metabolic syndrome. However, a short course of TRT could not improve the ICP response in hypogonadal aged male rats. Further investigation is necessary to clarify the exact rationale of TRT on the visceral fat cell. PMID:25767790

  17. Behavioral variation and reproductive success of male baboons (Papio anubis x Papio hamadryas) in a hybrid social group.

    PubMed

    Bergman, Thore J; Phillips-Conroy, Jane E; Jolly, Clifford J

    2008-02-01

    We take advantage of an array of hybrid baboons (Papio anubis x Papio hamadryas) living in the same social group to explore the causes and consequences of different male mating strategies. Male hamadryas hold one-male units and exhibit a sustained, intense interest in adult females, regardless of the latter's reproductive state. Anubis baboons, by contrast, live in multi-male, multi-female groups where males compete for females only when the latter are estrous. These two taxa interbreed to form a hybrid zone in the Awash National Park, Ethiopia, where previous work has suggested that hybrid males have intermediate and ineffective behavior. Here, we first examine male mating strategies with respect to morphological and genetic measures of ancestry. We found significant relationships between behavioral measures and morphology; males with more hamadryas-like morphology had more hamadryas-like behavior. However, genetic ancestry was not related to behavior, and in both cases intermediates displayed a previously unreported level of behavioral variation. Furthermore, male behavior was unrelated to natal group. Second, we evaluated reproductive success by microsatellite-based paternity testing. The highest reproductive success was found for individuals exhibiting intermediate behaviors. Moreover, over nine years, some genetically and morphologically intermediate males had high reproductive success. We conclude that the behavior of hybrid males is therefore unlikely to be an absolute barrier to admixture in the region. PMID:17724672

  18. Kinship-based politics and the optimal size of kin groups

    PubMed Central

    Hammel, E. A.

    2005-01-01

    Kin form important political groups, which change in size and relative inequality with demographic shifts. Increases in the rate of population growth increase the size of kin groups but decrease their inequality and vice versa. The optimal size of kin groups may be evaluated from the marginal political product (MPP) of their members. Culture and institutions affect levels and shapes of MPP. Different optimal group sizes, from different perspectives, can be suggested for any MPP schedule. The relative dominance of competing groups is determined by their MPP schedules. Groups driven to extremes of sustainability may react in Malthusian fashion, including fission and fusion, or in Boserupian fashion, altering social technology to accommodate changes in size. The spectrum of alternatives for actors and groups, shaped by existing institutions and natural and cultural selection, is very broad. Nevertheless, selection may result in survival of particular kinds of political structures. PMID:16091466

  19. Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors.

    PubMed

    Sonerud, Geir A; Steen, Ronny; Løw, Line M; Røed, Line T; Skar, Kristin; Selås, Vidar; Slagsvold, Tore

    2013-05-01

    In birds with bi-parental care, the provisioning link between prey capture and delivery to dependent offspring is regarded as often symmetric between the mates. However, in raptors, the larger female usually broods and feeds the nestlings, while the smaller male provides food for the family, assisted by the female in the latter part of the nestling period, if at all. Prey items are relatively large and often impossible for nestlings to handle without extended maternal assistance. We video-recorded prey delivery and handling in nests of a raptor with a wide diet, the Eurasian kestrel Falco tinnunculus, and simultaneously observed prey transfer from male to female outside the nest. The male selectively allocated larger items, in particular birds and larger mammals, to the female for further processing and feeding of nestlings, and smaller items, in particular lizards and smaller mammals, directly to the nestlings for unassisted feeding. Hence, from the video, the female appeared to have captured larger prey than the male, while in reality no difference existed. The female's size-biased interception of the male's prey provisioning line would maximize the male's foraging time, and maximize the female's control of the allocation of food between her own need and that of the offspring. The male would maximize his control of food allocation by capturing smaller prey. This conflict would select for larger dominant females and smaller energy-efficient males, and induce stronger selection the longer the female depends on the male for self-feeding, as a proportion of the offspring dependence period. PMID:23073637

  20. Variable ecological conditions promote male helping by changing banded mongoose group composition

    PubMed Central

    Sanderson, Jennifer L.; Mwanghuya, Francis; Businge, Robert; Kyabulima, Solomon; Hares, Michelle C.; Inzani, Emma; Kalema-Zikusoka, Gladys; Mwesige, Kenneth; Thompson, Faye J.; Vitikainen, Emma I. K.; Cant, Michael A.

    2016-01-01

    Ecological conditions are expected to have an important influence on individuals’ investment in cooperative care. However, the nature of their effects is unclear: both favorable and unfavorable conditions have been found to promote helping behavior. Recent studies provide a possible explanation for these conflicting results by suggesting that increased ecological variability, rather than changes in mean conditions, promote cooperative care. However, no study has tested whether increased ecological variability promotes individual-level helping behavior or the mechanisms involved. We test this hypothesis in a long-term study population of the cooperatively breeding banded mongoose, Mungos mungo, using 14 years of behavioral and meteorological data to explore how the mean and variability of ecological conditions influence individual behavior, body condition, and survival. Female body condition was more sensitive to changes in rainfall leading to poorer female survival and pronounced male-biased group compositions after periods of high rainfall variability. After such periods, older males invested more in helping behavior, potentially because they had fewer mating opportunities. These results provide the first empirical evidence for increased individual helping effort in more variable ecological conditions and suggest this arises because of individual differences in the effect of ecological conditions on body condition and survival, and the knock-on effect on social group composition. Individual differences in sensitivity to environmental variability, and the impacts this has on the internal structure and composition of animal groups, can exert a strong influence on the evolution and maintenance of social behaviors, such as cooperative care. PMID:27418750

  1. Interactions among social monitoring, anti-predator vigilance and group size in eastern grey kangaroos

    PubMed Central

    Favreau, François-René; Goldizen, Anne W.; Pays, Olivier

    2010-01-01

    Group size is known to affect both the amount of time that prey animals spend in vigilance and the degree to which the vigilance of group members is synchronized. However, the variation in group-size effects reported in the literature is not yet understood. Prey animals exhibit vigilance both to protect themselves against predators and to monitor other group members, and both forms of vigilance presumably influence group-size effects on vigilance. However, our understanding of the patterns of individual investment underlying the time sharing between anti-predator and social vigilance is still limited. We studied patterns of variation in individual vigilance and the synchronization of vigilance with group size in a wild population of eastern grey kangaroos (Macropus giganteus) subject to predation, in particular focusing on peripheral females because we expected that they would exhibit both social and anti-predator vigilance. There was no global effect of group size on individual vigilance. The lack of group-size effect was the result of two compensating effects. The proportion of time individuals spent looking at other group members increased, whereas the proportion of time they spent scanning the environment decreased with group size; as a result, overall vigilance levels did not change with group size. Moreover, a degree of synchrony of vigilance occurred within groups and that degree increased with the proportion of vigilance time peripheral females spent in anti-predator vigilance. Our results highlight the crucial roles of both social and anti-predator components of vigilance in the understanding of the relationship between group size and vigilance, as well as in the synchronization of vigilance among group members. PMID:20219737

  2. Estimation of Aedes aegypti (Diptera: Culicidae) population size and adult male survival in an urban area in Panama

    PubMed Central

    Neira, Marco; Lacroix, Renaud; Cáceres, Lorenzo; Kaiser, Paul E; Young, Josue; Pineda, Lleysa; Black, Isaac; Sosa, Nestor; Nimmo, Derric; Alphey, Luke; McKemey, Andrew

    2014-01-01

    Traditional mosquito control strategies rely heavily on the use of chemical insecticides. However, concerns about the efficiency of traditional control methods, environmental impact and emerging pesticide resistance have highlighted the necessity for developing innovative tools for mosquito control. Some novel strategies, including release of insects carrying a dominant lethal gene (RIDL®), rely on the sustained release of modified male mosquitoes and therefore benefit from a thorough understanding of the biology of the male of the species. In this report we present the results of a mark-release-recapture study aimed at: (i) establishing the survival in the field of laboratory-reared, wild-type male Aedes aegypti and (b) estimating the size of the local adult Ae. aegypti population. The study took place in Panama, a country where recent increases in the incidence and severity of dengue cases have prompted health authorities to evaluate alternative strategies for vector control. Results suggest a life expectancy of 2.3 days for released male mosquitoes (confidence interval: 1.78-2.86). Overall, the male mosquito population was estimated at 58 males/ha (range 12-81 males/ha), which can be extrapolated to an average of 0.64 pupae/person for the study area. The practical implications of these results are discussed. PMID:25410991

  3. Estimation of Aedes aegypti (Diptera: Culicidae) population size and adult male survival in an urban area in Panama.

    PubMed

    Neira, Marco; Lacroix, Renaud; Cáceres, Lorenzo; Kaiser, Paul E; Young, Josue; Pineda, Lleysa; Black, Isaac; Sosa, Nestor; Nimmo, Derric; Alphey, Luke; McKemey, Andrew

    2014-11-01

    Traditional mosquito control strategies rely heavily on the use of chemical insecticides. However, concerns about the efficiency of traditional control methods, environmental impact and emerging pesticide resistance have highlighted the necessity for developing innovative tools for mosquito control. Some novel strategies, including release of insects carrying a dominant lethal gene (RIDL®), rely on the sustained release of modified male mosquitoes and therefore benefit from a thorough understanding of the biology of the male of the species. In this report we present the results of a mark-release-recapture study aimed at: (i) establishing the survival in the field of laboratory-reared, wild-type male Aedes aegypti and (b) estimating the size of the local adult Ae. aegypti population. The study took place in Panama, a country where recent increases in the incidence and severity of dengue cases have prompted health authorities to evaluate alternative strategies for vector control. Results suggest a life expectancy of 2.3 days for released male mosquitoes (confidence interval: 1.78-2.86). Overall, the male mosquito population was estimated at 58 males/ha (range 12-81 males/ha), which can be extrapolated to an average of 0.64 pupae/person for the study area. The practical implications of these results are discussed. PMID:25410991

  4. Estimation of Aedes aegypti (Diptera: Culicidae) population size and adult male survival in an urban area in Panama.

    PubMed

    Neira, Marco; Lacroix, Renaud; Cáceres, Lorenzo; Kaiser, Paul E; Young, Josue; Pineda, Lleysa; Black, Isaac; Sosa, Nestor; Nimmo, Derric; Alphey, Luke; McKemey, Andrew

    2014-08-22

    Traditional mosquito control strategies rely heavily on the use of chemical insecticides. However, concerns about the efficiency of traditional control methods, environmental impact and emerging pesticide resistance have highlighted the necessity for developing innovative tools for mosquito control. Some novel strategies, including release of insects carrying a dominant lethal gene (RIDL®), rely on the sustained release of modified male mosquitoes and therefore benefit from a thorough understanding of the biology of the male of the species. In this report we present the results of a mark-release-recapture study aimed at: (i) establishing the survival in the field of laboratory-reared, wild-type male Aedes aegypti and (b) estimating the size of the local adult Ae. aegypti population. The study took place in Panama, a country where recent increases in the incidence and severity of dengue cases have prompted health authorities to evaluate alternative strategies for vector control. Results suggest a life expectancy of 2.3 days for released male mosquitoes (confidence interval: 1.78-2.86). Overall, the male mosquito population was estimated at 58 males/ha (range 12-81 males/ha), which can be extrapolated to an average of 0.64 pupae/person for the study area. The practical implications of these results are discussed. PMID:25165979

  5. Effect of group size on behavior, health, production and welfare of veal calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of the present study was to determine the effect of group size on behavior, health, growth, and welfare of veal calves. Holstein-Friesian bull calves (n = 168), 44 ± 3 days of age, were used to investigate the effect of group size. Calves were randomly assigned into 1 of 3 treatments o...

  6. Male Kirtland's Warblers' patch-level response to landscape structure during periods of varying population size and habitat amounts

    USGS Publications Warehouse

    Donner, D.M.; Ribic, C.A.; Probst, J.R.

    2009-01-01

    Forest planners must evaluate how spatiotemporal changes in habitat amount and configuration across the landscape as a result of timber management will affect species' persistence. However, there are few long-term programs available for evaluation. We investigated the response of male Kirtland's Warbler (Dendroica kirtlandii) to 26 years of changing patch and landscape structure during a large, 26-year forestry-habitat restoration program within the warbler's primary breeding range. We found that the average density of male Kirtland's Warblers was related to a different combination of patch and landscape attributes depending on the species' regional population level and habitat amounts on the landscape (early succession jack pine (Pinus banksiana) forests; 15-42% habitat cover). Specifically, patch age and habitat regeneration type were important at low male population and total habitat amounts, while patch age and distance to an occupied patch were important at relatively high population and habitat amounts. Patch age and size were more important at increasing population levels and an intermediate amount of habitat. The importance of patch age to average male density during all periods reflects the temporal buildup and decline of male numbers as habitat suitability within the patch changed with succession. Habitat selection (i.e., preference for wildfire-regenerated habitat) and availability may explain the importance of habitat type and patch size during lower population and habitat levels. The relationship between male density and distance when there was the most habitat on the landscape and the male population was large and still increasing may be explained by the widening spatial dispersion of the increasing male population at the regional scale. Because creating or preserving habitat is not a random process, management efforts would benefit from more investigations of managed population responses to changes in spatial structure that occur through habitat gain

  7. Male eyespan size is associated with meiotic drive in wild stalk-eyed flies (Teleopsis dalmanni).

    PubMed

    Cotton, A J; Földvári, M; Cotton, S; Pomiankowski, A

    2014-04-01

    This study provides the first direct evidence from wild populations of stalk-eyed flies to support the hypothesis that male eyespan is a signal of meiotic drive. Several stalk-eyed fly species are known to exhibit X-linked meiotic drive. A recent quantitative trait locus analysis in Teleopsis dalmanni found a potential link between variation in male eyespan, a sexually selected ornamental trait, and the presence of meiotic drive. This was based on laboratory populations subject to artificial selection for male eyespan. In this study, we examined the association between microsatellite markers and levels of sex ratio bias (meiotic drive) in 12 wild T. dalmanni populations. We collected two data sets: (a) brood sex ratios of wild-caught males mated to standard laboratory females and (b) variation in a range of phenotypic traits associated with reproductive success of wild-caught males and females. In each case, we typed individuals for eight X-linked microsatellite markers, including several that previously were shown to be associated with male eyespan and meiotic drive. We found that one microsatellite marker was very strongly associated with meiotic drive, whereas a second showed a weaker association. We also found that, using both independent data sets, meiotic drive was strongly associated with male eyespan, with smaller eyespan males being associated with more female-biased broods. These results suggest that mate preference for exaggerated male eyespan allows females to avoid mating with males carrying the meiotic drive gene and is thus a potential mechanism for the maintenance and evolution of female mate preference. PMID:24398884

  8. Ranging behavior, group size and behavioral flexibility in Ethiopian hamadryas baboons (Papio hamadryas hamadryas).

    PubMed

    Swedell, Larissa

    2002-01-01

    This study reports group size, home range size, daily path lengths, seasonal effects on ranging behavior and qualitative information on diet for a population of hamadryas baboons inhabiting the lowlands of the northern Rift Valley in central Ethiopia. The minimum home range size and daily path length for this population are similar to those reported for other populations of hamadryas baboons in Ethiopia and Saudi Arabia. Group sizes, however, are much larger than those in most other hamadryas populations for which published data are available. The large group sizes in this area may be related to the abundance of one food resource in particular, doum palm nuts. Overall, this study suggests that hamadryas baboons may be more flexible in some aspects of their behavioral ecology (e.g. group size) than in others (e.g. ranging behavior). PMID:12207056

  9. 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…

  10. Nonlinear effects of group size on the success of wolves hunting elk

    USGS Publications Warehouse

    MacNulty, D.R.; Smith, D.W.; Mech, L.D.; Vucetich, J.A.; Packer, C.

    2012-01-01

    Despite the popular view that social predators live in groups because group hunting facilitates prey capture, the apparent tendency for hunting success to peak at small group sizes suggests that the formation of large groups is unrelated to prey capture. Few empirical studies, however, have tested for nonlinear relationships between hunting success and group size, and none have demonstrated why success trails off after peaking. Here, we use a unique dataset of observations of individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park to show that the relationship between success and group size is indeed nonlinear and that individuals withholding effort (free riding) is why success does not increase across large group sizes. Beyond 4 wolves, hunting success leveled off, and individual performance (a measure of effort) decreased for reasons unrelated to interference from inept hunters, individual age, or size. But performance did drop faster among wolves with an incentive to hold back, i.e., nonbreeders with no dependent offspring, those performing dangerous predatory tasks, i.e., grabbing and restraining prey, and those in groups of proficient hunters. These results suggest that decreasing performance was free riding and that was why success leveled off in groups with >4 wolves that had superficially appeared to be cooperating. This is the first direct evidence that nonlinear trends in group hunting success reflect a switch from cooperation to free riding. It also highlights how hunting success per se is unlikely to promote formation and maintenance of large groups. ?? 2011 The Author.

  11. Nonlinear effects of group size on the success of wolves hunting elk

    USGS Publications Warehouse

    MacNulty, Daniel R.; Smith, Douglas W.; Mech, L. David; Vucetich, John A.; Packer, Craig

    2012-01-01

    Despite the popular view that social predators live in groups because group hunting facilitates prey capture, the apparent tendency for hunting success to peak at small group sizes suggests that the formation of large groups is unrelated to prey capture. Few empirical studies, however, have tested for nonlinear relationships between hunting success and group size, and none have demonstrated why success trails off after peaking. Here, we use a unique dataset of observations of individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park to show that the relationship between success and group size is indeed nonlinear and that individuals withholding effort (free riding) is why success does not increase across large group sizes. Beyond 4 wolves, hunting success leveled off, and individual performance (a measure of effort) decreased for reasons unrelated to interference from inept hunters, individual age, or size. But performance did drop faster among wolves with an incentive to hold back, i.e., nonbreeders with no dependent offspring, those performing dangerous predatory tasks, i.e., grabbing and restraining prey, and those in groups of proficient hunters. These results suggest that decreasing performance was free riding and that was why success leveled off in groups with >4 wolves that had superficially appeared to be cooperating. This is the first direct evidence that nonlinear trends in group hunting success reflect a switch from cooperation to free riding. It also highlights how hunting success per se is unlikely to promote formation and maintenance of large groups.

  12. Group size alters postures, and maintenance, oral, locomotor and social behaviors of veal calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate the effect of group size on behavior of veal calves. Holstein-Friesian bull calves (n = 168; 44 ± 3 d of age), were randomly assigned to 1 of 3 treatments of group housing with 2, 4, or 8 calves per pen (1.82 m2 per calf for all groups). Behavior was obser...

  13. Online focus groups as an HIV prevention program for gay, bisexual, and queer adolescent males.

    PubMed

    Ybarra, Michele L; DuBois, L Zachary; Parsons, Jeffrey T; Prescott, Tonya L; Mustanski, Brian

    2014-12-01

    Seventy-five 14-18-year-old gay, bisexual, and queer (GBQ) males provided feedback about how their participation in national, online focus groups (FG) about GBQ sexual health related topics resulted in behavioral and attitudinal changes. Most sexually experienced youth agreed that their participation positively changed their views and behavioral intentions. Some said that being in the FG made them more comfortable talking about sex, their sexuality, and making safer choices such as negotiating condoms. Others indicated intentions to become more involved in the LGBT community. Sexually inexperienced FG participants similarly said that the FG discussion positively affected them-most commonly by reducing their sense of isolation as young GBQ men who were waiting to have sex. Many also thought that they would become more vocal advocates of abstinence and/or safe sex. Online FGs and facilitated discussion boards should be further explored as a low-cost HIV prevention program for GBQ youth. PMID:25490735

  14. Online focus groups as an HIV prevention program for gay, bisexual, and queer adolescent males

    PubMed Central

    Ybarra, Michele L.; DuBois, L. Zachary; Parsons, Jeffrey T.; Prescott, Tonya L.; Mustanski, Brian

    2015-01-01

    Seventy-five 14–18-year-old gay, bisexual, and queer (GBQ) males provided feedback about how their participation in national, online focus groups (FG) about GBQ sexual health related topics resulted in behavioral and attitudinal changes. Most sexually experienced youth agreed that their participation positively changed their views and behavioral intentions. Some said that being in the FG made them more comfortable talking about sex, their sexuality, and making safer choices such as negotiating condoms. Others indicated intentions to become more involved in the LGBT community. Sexually inexperienced FG participants similarly said that the FG discussion positively affected them - most commonly by reducing their sense of isolation as young GBQ men who were waiting to have sex. Many also thought that they would become more vocal advocates of abstinence and/or safe sex. Online FGs and facilitated discussion boards should be further explored as a low-cost HIV prevention program for GBQ youth. PMID:25490735

  15. Consequences of intraspecific variation in female body size in Stagmomantis limbata (Mantodea: Mantidae): feeding ecology, male attraction, and egg production.

    PubMed

    Maxwell, Michael R; Frinchaboy, Caylin

    2014-02-01

    Body size is an important feature of organisms, influencing many components of life history and fitness, such as feeding success and reproductive output. Body size is considered especially salient for solitary predators, whose food intake hinges on individual predation success, which in turn is often driven by the relative sizes of predator and prey. The current study examined intraspecific variation in adult female length and its fitness consequences in a solitary predator, the praying mantid Stagmomantis limbata Hahn. Through a 5-yr integration of observational and experimental work in the field and captivity, we investigated the relationship between female pronotum length and prey size, diet breadth, male attraction, and measures of egg production (fecundity and ootheca mass). We found that longer females ate longer prey in the field and showed greater breadth of prey size than shorter females. Longer females did not necessarily feed at higher rates in the field, as measured by the rate of abdominal expansion. Female length failed to show significant effects on male attraction or on the incidence of cannibalism. Longer females had higher fecundity (mature eggs in body at death) and laid heavier oothecae than shorter females. In nature, longer females consistently emerged as adults earlier in the season than shorter females. Shorter female adults emerged when feeding rates were higher in the field, suggesting an incidental ecological benefit of shorter adult size. PMID:24341955

  16. The Effects of Group Size, Memory Instruction, and Session Length on the Creative Performance in Electronic Brainstorming Groups

    ERIC Educational Resources Information Center

    Coskun, Hamit

    2011-01-01

    In the literature, there has been a focus on the effectiveness of larger sized electronic brainstorming groups; however, mechanisms for its effectiveness still remain open to question and some methodological concerns (e.g., the evaluation of ideas and the typing speed, and the use of different formats) continue to be important problems. To…

  17. The role of micro size computing clusters for small physics groups

    NASA Astrophysics Data System (ADS)

    Shevel, A. Y.

    2014-06-01

    A small physics group (3-15 persons) might use a number of computing facilities for the analysis/simulation, developing/testing, teaching. It is discussed different types of computing facilities: collaboration computing facilities, group local computing cluster (including colocation), cloud computing. The author discuss the growing variety of different computing options for small groups and does emphasize the role of the group owned computing cluster of micro size.

  18. Prenatal exposure to phthalates is associated with decreased anogenital distance and penile size in male newborns

    PubMed Central

    Bustamante-Montes, L P; Hernández-Valero, M A; Flores-Pimentel, D; García-Fábila, M; Amaya-Chávez, A; Barr, D B; Borja-Aburto, V H

    2013-01-01

    Reproductive effects from phthalate exposure have been documented mostly in animal studies. This study explored the association between prenatal exposure to phthalate metabolites, anogenital distance and penile measurements in male newborns in Toluca, State of Mexico. A total of 174 pregnant women provided urine samples for phthalate analysis during their last prenatal visit, and the 73 who gave birth to male infants were included in the study. The 73 male newborns were weighed and measured using standardized methods after delivery. After adjusting for creatinine and supine length at birth, significant inverse associations were observed between an index of prenatal exposure to total phthalate exposure and the distance from the anus to anterior base of the penis (β = −0.191 mm per 1 µg/l, P = 0.037), penile width (β = −0.0414, P = 0.050) and stretched length (β = −0.2137, P = 0.034); prenatal exposure to mono-2-ethylhexyl phthalate exposure was associated with a reduction in the stretched length of the penis (β = −0.2604, P = 0.050). Human exposure to phthalates is a public health concern, and the system most vulnerable to its potential effects seems to be the immature male reproductive tract. PMID:24349678

  19. Prenatal exposure to phthalates is associated with decreased anogenital distance and penile size in male newborns.

    PubMed

    Bustamante-Montes, L P; Hernández-Valero, M A; Flores-Pimentel, D; García-Fábila, M; Amaya-Chávez, A; Barr, D B; Borja-Aburto, V H

    2013-08-01

    Reproductive effects from phthalate exposure have been documented mostly in animal studies. This study explored the association between prenatal exposure to phthalate metabolites, anogenital distance and penile measurements in male newborns in Toluca, State of Mexico. A total of 174 pregnant women provided urine samples for phthalate analysis during their last prenatal visit, and the 73 who gave birth to male infants were included in the study. The 73 male newborns were weighed and measured using standardized methods after delivery. After adjusting for creatinine and supine length at birth, significant inverse associations were observed between an index of prenatal exposure to total phthalate exposure and the distance from the anus to anterior base of the penis (β = -0.191 mm per 1 μg/l, P = 0.037), penile width (β = -0.0414, P = 0.050) and stretched length (β = -0.2137, P = 0.034); prenatal exposure to mono-2-ethylhexyl phthalate exposure was associated with a reduction in the stretched length of the penis (β = -0.2604, P = 0.050). Human exposure to phthalates is a public health concern, and the system most vulnerable to its potential effects seems to be the immature male reproductive tract. PMID:24349678

  20. Photoperiod and melatonin treatments for controlling sperm parameters, testicular and accessory sex glands size in male Iberian ibex: A model for captive mountain ruminants.

    PubMed

    Santiago-Moreno, J; Toledano-Díaz, A; Castaño, C; Coloma, M A; Esteso, M C; Prieto, M T; Delgadillo, J A; López-Sebastián, A

    2013-06-01

    This study examines whether photoperiod and/or melatonin treatments can improve sperm variables outside the breeding season in the Iberian ibex-a model species for wild mountain ruminants-thus helping in the collection of high quality sperm beyond the normal breeding season for depositing in genetic resource banks. Adult Iberian ibex males (n=17) were divided into four treatment groups: (1) controls under the natural photoperiod (control group; n=4), (2) treatment with melatonin implants on December 22nd, February 22nd and April 22nd (group WS-M; n=5), (3) treatment with short photoperiod cycles, i.e., 2 months of long days followed by melatonin implants (to emulate 2 months of short days) throughout the year (group PHPld+M; n=4), and (4) treatment with melatonin implants on June 22nd and August 22nd (group SS-M; n=4). The interaction treatment x season had a strong influence on testis size (P<0.05), the size of the seminal vesicles (P<0.001), the percentage of abnormal sperms (P<0.05), and percentage non-progressive (P<0.05) and progressive (P<0.001) sperm motility. In groups WS-M and PHPld+M, the normal springtime physiological reductions in testis size, non-progressive sperm motility and acrosome integrity were prevented. The values for the studied sperm variables were, however, reduced in the natural breeding season at the end of the experimental period in group PHPld+M, although not in group WS-M. The pattern of melatonin administration in group SS-M conferred no advantages on reproductive functionality. These results suggest that lengthening the short day period after the winter solstice (the WS-M treatment) extends reproductive activity in this species, allowing good quality sperm to be recovered for conservation purposes during the non-breeding season. PMID:23664101

  1. Rearing-group size determines social competence and brain structure in a cooperatively breeding cichlid.

    PubMed

    Fischer, Stefan; Bessert-Nettelbeck, Mathilde; Kotrschal, Alexander; Taborsky, Barbara

    2015-07-01

    Social animals can greatly benefit from well-developed social skills. Because the frequency and diversity of social interactions often increase with the size of social groups, the benefits of advanced social skills can be expected to increase with group size. Variation in social skills often arises during ontogeny, depending on early social experience. Whether variation of social-group sizes affects development of social skills and related changes in brain structures remains unexplored. We investigated whether, in a cooperatively breeding cichlid, early group size (1) shapes social behavior and social skills and (2) induces lasting plastic changes in gross brain structures and (3) whether the development of social skills is confined to a sensitive ontogenetic period. Rearing-group size and the time juveniles spent in these groups interactively influenced the development of social skills and the relative sizes of four main brain regions. We did not detect a sensitive developmental period for the shaping of social behavior within the 2-month experience phase. Instead, our results suggest continuous plastic behavioral changes over time. We discuss how developmental effects on social behavior and brain architecture may adaptively tune phenotypes to their current or future environments. PMID:26098344

  2. Increased reproductive effort results in male-biased offspring sex ratio: an experimental study in a species with reversed sexual size dimorphism.

    PubMed Central

    Kalmbach, E.; Nager, R. G.; Griffiths, R.; Furness, R. W.

    2001-01-01

    Adaptive sex-ratio theory predicts that parents should overproduce the more beneficial offspring sex. Based on a recent experimental study of lesser black-backed gulls, we tested this hypothesis with the great skua, Catharacta skua, a bird species closely related to gulls but where females are the larger sex. When in poor body condition, the gulls overproduced daughters, the smaller and more viable sex under those circumstances. To discriminate between a mandatory physiological overproduction of female (i.e. non-male) eggs versus the overproduction of the smaller and presumably more viable sex, we conducted an egg-removal experiment with the great skua. Since the males are smaller, larger size and being male are separated. Through egg removal we induced females to increase egg production effort. Eggs were sexed using a DNA-based technique. Manipulated pairs produced a significant male bias at the end of the extended laying sequence, while the sex ratio in the control group did not differ from unity. Our results present an example of facultative sex-ratio manipulation and support the hypothesis that in sexually dimorphic birds parents overproduce the smaller sex under adverse conditions. PMID:11600083

  3. Infectious disease and group size: more than just a numbers game

    PubMed Central

    Nunn, Charles L.; Jordán, Ferenc; McCabe, Collin M.; Verdolin, Jennifer L.; Fewell, Jennifer H.

    2015-01-01

    Increased risk of infectious disease is assumed to be a major cost of group living, yet empirical evidence for this effect is mixed. We studied whether larger social groups are more subdivided structurally. If so, the social subdivisions that form in larger groups may act as barriers to the spread of infection, weakening the association between group size and infectious disease. To investigate this ‘social bottleneck’ hypothesis, we examined the association between group size and four network structure metrics in 43 vertebrate and invertebrate species. We focused on metrics involving modularity, clustering, distance and centralization. In a meta-analysis of intraspecific variation in social networks, modularity showed positive associations with network size, with a weaker but still positive effect in cross-species analyses. Network distance also showed a positive association with group size when using intraspecific variation. We then used a theoretical model to explore the effects of subgrouping relative to other effects that influence disease spread in socially structured populations. Outbreaks reached higher prevalence when groups were larger, but subgrouping reduced prevalence. Subgrouping also acted as a ‘brake’ on disease spread between groups. We suggest research directions to understand the conditions under which larger groups become more subdivided, and to devise new metrics that account for subgrouping when investigating the links between sociality and infectious disease risk. PMID:25870397

  4. Humidity and seasonality drives body size patterns in males of the bush cricket Isophya rizeensis Sevgili, 2003 (Orthoptera: Tettigoniidae: Phaneropterinae).

    PubMed

    Cağlar, Selim S; Karacaoğlu, Cağaşan; Kuyucu, A Cem; Sağlam, Ismail K

    2014-04-01

    Two primary patterns of body size variation have been recorded in ectotherms in relation to latitudinal/altitudinal shifts. In some, body size increases with increasing latitude/altitude whereas, in others, body size decreases with increasing latitude/altitude. This clinal variation is generally assumed to be caused by local adaptation to environmental conditions however the selective variable(s) (temperature, humidity, diet quality, etc.) is still heavily debated. Here we investigate geographic variation in body size of dark and pale color morphs of males of the bush-cricket Isophya rizeensis collected from 15 locations along an elevation gradient ranging from 350 to 2 500 m. Using an information theoretical approach we evaluate the relative support of four different hypotheses (the temperature size rule, the moisture gradient hypothesis, the seasonal constraint hypothesis, and the primary productivity hypothesis) explaining body size variation along the altitudinal gradient. Body size variation in pale color morphs showed a curvilinear relationship with altitude while dark color morphs showed no variation in body size. Body size variation in pale color morphs was highly correlated with precipitation and temperature seasonality values thus giving strong support for the moisture gradient and seasonal constraint hypothesis. Our results reinforce the importance of gradients in humidity and seasonality over temperature in the creation of altitudinal body size clines and the role of selection for resistance to stress factors in the establishment of these clines. Whether a body size cline is observed or not might also depend on the phenotypic properties of the individuals, like coloration. PMID:23956203

  5. A Life-Cycle Model of Human Social Groups Produces a U-Shaped Distribution in Group Size

    PubMed Central

    Salali, Gul Deniz; Whitehouse, Harvey; Hochberg, Michael E.

    2015-01-01

    One of the central puzzles in the study of sociocultural evolution is how and why transitions from small-scale human groups to large-scale, hierarchically more complex ones occurred. Here we develop a spatially explicit agent-based model as a first step towards understanding the ecological dynamics of small and large-scale human groups. By analogy with the interactions between single-celled and multicellular organisms, we build a theory of group lifecycles as an emergent property of single cell demographic and expansion behaviours. We find that once the transition from small-scale to large-scale groups occurs, a few large-scale groups continue expanding while small-scale groups gradually become scarcer, and large-scale groups become larger in size and fewer in number over time. Demographic and expansion behaviours of groups are largely influenced by the distribution and availability of resources. Our results conform to a pattern of human political change in which religions and nation states come to be represented by a few large units and many smaller ones. Future enhancements of the model should include decision-making rules and probabilities of fragmentation for large-scale societies. We suggest that the synthesis of population ecology and social evolution will generate increasingly plausible models of human group dynamics. PMID:26381745

  6. Accounting for One-Group Clustering in Effect-Size Estimation

    ERIC Educational Resources Information Center

    Citkowicz, Martyna; Hedges, Larry V.

    2013-01-01

    In some instances, intentionally or not, study designs are such that there is clustering in one group but not in the other. This paper describes methods for computing effect size estimates and their variances when there is clustering in only one group and the analysis has not taken that clustering into account. The authors provide the effect size…

  7. Lack of association between mutation size and cognitive/behavior deficits in fragile X males: A brief report

    SciTech Connect

    Fisch, G.S.; Simensen, R.

    1996-08-09

    Previously, researchers reported molecular-neurobehavioral or molecular-cognitive associations in individuals with fra(X) (fragile X) mutation. However, not all investigators have noted molecular-behavioral relationships. Consequently, we examined prospectively 30 fra(X) males age 3-15 years from four testing sites to determine whether there was a relationship between mutation size and degree of either cognitive or adaptive behavior deficit. To measure cognitive abilities, all individuals were administered the Stanford-Binet (4th edition) IQ test. To evaluate adaptive behavior (DQ) skills, all individuals were assessed using the Vineland Adaptive Behavior Scale. To determine fra(X) status, genomic DNA from all individuals was extracted and digested with EcoRI and EagI restriction enzymes. Southern blots were prepared and hybridized with the pE5.1 probe. The Pearson correlation coefficient between full mutation size and composite IQ score revealed a non-significant, near-zero association (r = 0.06; P > .76). The Pearson coefficient between mutation size and DQ also showed a non-significant, near-zero association (r = 0.06; P >.73). We conclude that while fra(X) mutation produces cognitive and behavior deficits in males who inherit the defective gene, there is no relationship between mutation size and degree of deficit. 14 refs., 2 figs.

  8. Lack of association between mutation size and cognitive/behavior deficits in fragile X males: a brief report.

    PubMed

    Fisch, G S; Carpenter, N; Howard-Peebles, P N; Maddalena, A; Simensen, R; Tarleton, J; Julien-Inalsingh, C; Chalifoux, M; Holden, J J

    1996-08-01

    Previously, researchers reported molecular-neurobehavioral or molecular-cognitive associations in individuals with fra(X) (fragile X) mutation. However, not all investigators have noted molecular-behavioral relationships. Consequently, we examined prospectively 30 fra(X) males age 3-15 years from four testing sites to determine whether there was a relationship between mutation size and degree of either cognitive or adaptive behavior deficit. To measure cognitive abilities, all individuals were administered the Stanford-Binet (4th edition) IQ test. To evaluate adaptive behavior (DQ) skills, all individuals were assessed using the Vineland Adaptive Behavior Scale. To determine fra(X) status, genomic DNA from all individuals was extracted and digested with EcoRI and EagI restriction enzymes. Southern blots were prepared and hybridized with the pE5.1 probe. The Pearson correlation coefficient between full mutation size and composite IQ score revealed a nonsignificant, near-zero association (r = 0.06; P > .76). The Pearson coefficient between mutation size and DQ also showed a nonsignificant, near-zero association (r = 0.06; P > .73). We conclude that while fra(X) mutation produces cognitive and behavior deficits in males who inherit the defective gene, there is no relationship between mutation size and degree of deficit. PMID:8844081

  9. Ecological Correlates of Group-Size Variation in a Resource-Defense Ungulate, the Sedentary Guanaco

    PubMed Central

    Marino, Andrea; Baldi, Ricardo

    2014-01-01

    For large herbivores, predation-risk, habitat structure and population density are often reported as major determinants of group size variation within and between species. However, whether the underlying causes of these relationships imply an ecological adaptation or are the result of a purely mechanistic process in which fusion and fragmentation events only depend on the rate of group meeting, is still under debate. The aim of this study was to model guanaco family and bachelor group sizes in contrasting ecological settings in order to test hypotheses regarding the adaptive significance of group-size variation. We surveyed guanaco group sizes within three wildlife reserves located in eastern Patagonia where guanacos occupy a mosaic of grasslands and shrublands. Two of these reserves have been free from predators for decades while in the third, pumas often prey on guanacos. All locations have experienced important changes in guanaco abundance throughout the study offering the opportunity to test for density effects. We found that bachelor group size increased with increasing density, as expected by the mechanistic approach, but was independent of habitat structure or predation risk. In contrast, the smaller and territorial family groups were larger in the predator-exposed than in the predator-free locations, and were larger in open grasslands than in shrublands. However, the influence of population density on these social units was very weak. Therefore, family group data supported the adaptive significance of group-size variation but did not support the mechanistic idea. Yet, the magnitude of the effects was small and between-population variation in family group size after controlling for habitat and predation was negligible, suggesting that plasticity of these social units is considerably low. Our results showed that different social units might respond differentially to local ecological conditions, supporting two contrasting hypotheses in a single species, and

  10. Ecological correlates of group-size variation in a resource-defense ungulate, the sedentary guanaco.

    PubMed

    Marino, Andrea; Baldi, Ricardo

    2014-01-01

    For large herbivores, predation-risk, habitat structure and population density are often reported as major determinants of group size variation within and between species. However, whether the underlying causes of these relationships imply an ecological adaptation or are the result of a purely mechanistic process in which fusion and fragmentation events only depend on the rate of group meeting, is still under debate. The aim of this study was to model guanaco family and bachelor group sizes in contrasting ecological settings in order to test hypotheses regarding the adaptive significance of group-size variation. We surveyed guanaco group sizes within three wildlife reserves located in eastern Patagonia where guanacos occupy a mosaic of grasslands and shrublands. Two of these reserves have been free from predators for decades while in the third, pumas often prey on guanacos. All locations have experienced important changes in guanaco abundance throughout the study offering the opportunity to test for density effects. We found that bachelor group size increased with increasing density, as expected by the mechanistic approach, but was independent of habitat structure or predation risk. In contrast, the smaller and territorial family groups were larger in the predator-exposed than in the predator-free locations, and were larger in open grasslands than in shrublands. However, the influence of population density on these social units was very weak. Therefore, family group data supported the adaptive significance of group-size variation but did not support the mechanistic idea. Yet, the magnitude of the effects was small and between-population variation in family group size after controlling for habitat and predation was negligible, suggesting that plasticity of these social units is considerably low. Our results showed that different social units might respond differentially to local ecological conditions, supporting two contrasting hypotheses in a single species, and

  11. Does group size have an impact on welfare indicators in fattening pigs?

    PubMed

    Meyer-Hamme, S E K; Lambertz, C; Gauly, M

    2016-01-01

    Production systems for fattening pigs have been characterized over the last 2 decades by rising farm sizes coupled with increasing group sizes. These developments resulted in a serious public discussion regarding animal welfare and health in these intensive production systems. Even though large farm and group sizes came under severe criticism, it is still unknown whether these factors indeed negatively affect animal welfare. Therefore, the aim of this study was to assess the effect of group size (30 pigs/pen) on various animal-based measures of the Welfare Quality(®) protocol for growing pigs under conventional fattening conditions. A total of 60 conventional pig fattening farms with different group sizes in Germany were included. Moderate bursitis (35%) was found as the most prevalent indicator of welfare-related problems, while its prevalence increased with age during the fattening period. However, differences between group sizes were not detected (P>0.05). The prevalence of moderately soiled bodies increased from 9.7% at the start to 14.2% at the end of the fattening period, whereas large pens showed a higher prevalence (15.8%) than small pens (10.4%; P<0.05). With increasing group size, the incidence of moderate wounds with 8.5% and 11.3% in small- and medium-sized pens, respectively, was lower (P<0.05) than in large-sized ones (16.3%). Contrary to bursitis and dirtiness, its prevalence decreased during the fattening period. Moderate manure was less often found in pigs fed by a dry feeder than in those fed by a liquid feeding system (P<0.05). The human-animal relationship was improved in large in comparison to small groups. On the contrary, negative social behaviour was found more often in large groups. Exploration of enrichment material decreased with increasing live weight. Given that all animals were tail-docked, tail biting was observed at a very low rate of 1.9%. In conclusion, the results indicate that BW and feeding system are determining factors for

  12. Effect of pen size, group size, and stocking density on activity in freestall-housed dairy cows.

    PubMed

    Telezhenko, E; von Keyserlingk, M A G; Talebi, A; Weary, D M

    2012-06-01

    The purpose was to determine the effects of the physical dimensions of the pen and group size and stocking density on cow activity. Cows (randomly assigned to 4 groups of 6 animals each) were tested in pens with 24 or 12 lying places and in groups with 12 or 6 cows. All groups were tested in each of the 4 treatments with treatment order allocated using a 4 × 4 Latin square. The distance moved and the number of movements were calculated using 5-min scan sampling of video recordings over a 48-h period. Time spent lying down, number of lying bouts, and the duration of each lying bout were recorded using activity sensors. Displacements at the feed bunk were assessed by continuous analysis of video for 3h after the delivery of the fresh feed in the afternoon. Cows moved greater distances when kept in a large versus small pens (330.2 vs. 270.1 ± 11.6 m/d; mean ± SE), irrespective of group size. Cows moved more often when kept in the larger pen (21.3 vs. 19.2 ± 0.63% of scans). The time spent lying down decreased when density increased (59.1 vs. 55.8 ± 2.3% of scans at 25% and 100% stocking, respectively). Treatment had no effect on the number of displacements at the feed bunk. Physical dimensions of the pen play an important role in how much cows move, and stocking density affects lying time. PMID:22612942

  13. Joint-linkage mapping and GWAS reveal extensive genetic loci that regulate male inflorescence size in maize.

    PubMed

    Wu, Xun; Li, Yongxiang; Shi, Yunsu; Song, Yanchun; Zhang, Dengfeng; Li, Chunhui; Buckler, Edward S; Li, Yu; Zhang, Zhiwu; Wang, Tianyu

    2016-07-01

    Both insufficient and excessive male inflorescence size leads to a reduction in maize yield. Knowledge of the genetic architecture of male inflorescence is essential to achieve the optimum inflorescence size for maize breeding. In this study, we used approximately eight thousand inbreds, including both linkage populations and association populations, to dissect the genetic architecture of male inflorescence. The linkage populations include 25 families developed in the U.S. and 11 families developed in China. Each family contains approximately 200 recombinant inbred lines (RILs). The association populations include approximately 1000 diverse lines from the U.S. and China. All inbreds were genotyped by either sequencing or microarray. Inflorescence size was measured as the tassel primary branch number (TBN) and tassel length (TL). A total of 125 quantitative trait loci (QTLs) were identified (63 for TBN, 62 for TL) through linkage analyses. In addition, 965 quantitative trait nucleotides (QTNs) were identified through genomewide study (GWAS) at a bootstrap posterior probability (BPP) above a 5% threshold. These QTLs/QTNs include 24 known genes that were cloned using mutants, for example Ramosa3 (ra3), Thick tassel dwarf1 (td1), tasselseed2 (ts2), liguleless2 (lg2), ramosa1 (ra1), barren stalk1 (ba1), branch silkless1 (bd1) and tasselseed6 (ts6). The newly identified genes encode a zinc transporter (e.g. GRMZM5G838098 and GRMZM2G047762), the adapt in terminal region protein (e.g. GRMZM5G885628), O-methyl-transferase (e.g. GRMZM2G147491), helix-loop-helix (HLH) DNA-binding proteins (e.g. GRMZM2G414252 and GRMZM2G042895) and an SBP-box protein (e.g. GRMZM2G058588). These results provide extensive genetic information to dissect the genetic architecture of inflorescence size for the improvement of maize yield. PMID:26801971

  14. Male lineages in South American native groups: evidence of M19 traveling south.

    PubMed

    Toscanini, Ulises; Gusmão, Leonor; Berardi, Gabriela; Gomes, Verónica; Amorim, António; Salas, Antonio; Raimondi, Eduardo

    2011-10-01

    With this study, we aimed to determine the different male ancestral components of two Native American communities from Argentina, namely Toba and Colla. The analysis of 27 Y-chromosome SNPs allowed us to identify seven different haplogroups in both samples. Chromosomes carrying the M3 mutation, which typically defines the Native American haplogroup Q1a3a, were seen most frequently in the Toba community (90%). Conversely, Q1a3a was represented in 34% of the Colla Y-chromosomes, whereas haplogroup R1b1, the main representative of western European populations, exhibited the highest frequency in this population (41%). Different M3 sublineages in the Toba community could be identified by observing point mutations at both DYS385 and M19 loci. A microvariant at DYS385, named 16.1, has been characterized, which helps to further subdivide Q1a3a. It is the first time the M19 mutated allele is described in a population from Argentina. This finding supports the old age of the lineages carrying the M19 mutation, but it contradicts the previous hypothesis that the M19 mutated allele is confined to only two Equatorial-Tucano population groups from the north region of South America. The detection of M19 further south than previously thought allows questioning of the hypothesis that this lineage serves as an example of isolation after colonization. This observation also affirms the strong genetic drift to which Native Americans have been subjected. Moreover, our study illustrates a heterogeneous contribution of Europeans to these populations and supports previous studies showing that most Native American groups were subjected to European admixture that primarily involved immigrant men. PMID:21826635

  15. Producers and scroungers: feeding-type composition changes with group size in a socially foraging spider.

    PubMed

    Dumke, Marlis; Herberstein, Marie E; Schneider, Jutta M

    2016-04-13

    In groups of socially foraging animals, feeding behaviour may change with group size in response to varying cost-benefit trade-offs. Numerous studies have described group-size effects on group-average feeding behaviour, particularly emphasizing an increase in scrounging incidence for larger groups, where individuals (scroungers) feed from the food sources others (producers) discovered. However, individual variation in feeding behaviour remains unconsidered in the vast majority of these studies even though theoretical models predict individuals to specialize in feeding tactic and anticipate higher scrounger-type frequencies in larger groups. We combined group-level and individual-level analyses of group-size effects on social foraging in the subsocial spiderAustralomisidia ergandros Lending novel experimental support to model predictions, we found that individuals specialize in feeding tactic and that higher scrounging and lower producing incidence in larger groups were mediated through shifts in the ratio of feeding types. Further, feeding-type specialization was not explained by innate individual differences in hunting ability as all feeding types were equally efficient in prey capture when foraging alone. Context adaptivity of feeding behaviour might allow this subsocial species to succeed under varying socioecological conditions. PMID:27075253

  16. Personality composition is more important than group size in determining collective foraging behaviour in the wild

    PubMed Central

    Keiser, Carl N.; Pruitt, Jonathan N.

    2014-01-01

    Describing the factors that shape collective behaviour is central to our understanding of animal societies. Countless studies have demonstrated an effect of group size in the emergence of collective behaviours, but comparatively few have accounted for the composition/diversity of behavioural phenotypes, which is often conflated with group size. Here, we simultaneously examine the effect of personality composition and group size on nest architecture and collective foraging aggressiveness in the social spider Stegodyphus dumicola. We created colonies of two different sizes (10 or 30 individuals) and four compositions of boldness (all bold, all shy, mixed bold and shy, or average individuals) in the field and then measured their collective behaviour. Larger colonies produced bigger capture webs, while colonies containing a higher proportion of bold individuals responded to and attacked prey more rapidly. The number of attackers during collective foraging was determined jointly by composition and size, although composition had an effect size more than twice that of colony size: our results suggest that colonies of just 10 bold spiders would attack prey with as many attackers as colonies of 110 ‘average’ spiders. Thus, personality composition is a more potent (albeit more cryptic) determinant of collective foraging in these societies. PMID:25320170

  17. Rheotaxis performance increases with group size in a coupled phase model with sensory noise. The effects of noise and group size on rheotaxis

    NASA Astrophysics Data System (ADS)

    Chicoli, A.; Bak-Coleman, J.; Coombs, S.; Paley, D. A.

    2015-12-01

    Many fish exhibit rheotaxis, a behavior in which fish orient themselves relative to flow. Rheotaxis confers many benefits, including energetic cost savings and interception of drifting prey. Despite the fact that most species of fish school during at least some portion of their life, little is known about the importance of rheotactic behavior to schooling fish and, conversely, how the presence of nearby conspecifics affects rheotactic behavior. Understanding how rheotaxis is modified by social factors is thus of ecological importance. Here we present a mathematical model in the form of an all-to-all, coupled-oscillator framework over the non-Euclidean space of fish orientations to model group rheotactic behavior. Individuals in the model measure the orientation of their neighbors and the flow direction relative to their own orientation. These measures are corrupted by sensory noise. We study the effect of sensory noise and group size on internal (i.e., within the school) and external (i.e., with the flow) disagreement in orientation. We find that under noisy environmental conditions, increased group size improves rheotaxis. Results of this study have implications for understanding animal behavior, as well as for potential applications in bio-inspired engineering.

  18. Optimal Group Size for Software Change Tasks: A Social Information Foraging Perspective.

    PubMed

    Bhowmik, Tanmay; Niu, Nan; Wang, Wentao; Cheng, Jing-Ru C; Li, Ling; Cao, Xiongfei

    2016-08-01

    Group size is a key factor in collaborative software development and many other cybernetic applications where task assignments are important. While methods exist to estimate its value for proprietary projects, little is known about how group size affects distributed and decentralized cybernetic applications and in particular open source software (OSS) development. This paper presents a novel approach in which we frame developers' collective resolution of OSS change tasks as a social information foraging problem. This new perspective enables us to predict the optimal group size and quantify group size's effect on individual performance. We test the theory with data mined from two projects: 1) Firefox and 2) Mylyn. This paper not only uncovers the mismatch of optimal and actual group sizes, but also reveals the association of optimality with improved productivity. In addition, the social-level productivity gain is observed as project evolves. We show this paper's impact by extending the frontiers of knowledge in two areas: 1) social coding and 2) recommendation systems. PMID:25910274

  19. The Genetic Relatedness in Groups of Joint-Nesting Taiwan Yuhinas: Low Genetic Relatedness with Preferences for Male Kin

    PubMed Central

    Cheng, Yi-Ru; Li, Shou-Hsien; Fang, Shu; Pu, Chang-En; Yuan, Hsiao-Wei; Shen, Sheng-Feng

    2015-01-01

    The relative importance of direct and indirect fitness and, thus, the role of kinship in the evolution of social behavior is much debated. Studying the genetic relatedness of interacting individuals is crucial to improving our understanding of these issues. Here, we used a seven-year data set to study the genetic structure of the Taiwan yuhina (Yuhina brunneciceps), a joint-nesting passerine. Ten microsatellite loci were used to investigate the pair-wised relatedness among yuhina breeding group members. We found that the average genetic relatedness between same-sex group members was very low (0.069 for male dyads and 0.016 for female dyads). There was also a low ratio of closely-related kin (r>0.25) in the cooperative breeding groups of yuhinas (21.59% and 9.68% for male and female dyads, respectively). However, the relatedness of male dyads within breeding groups was significantly higher than female dyads. Our results suggest that yuhina cooperation is maintained primarily by direct fitness benefits to individuals; however, kin selection might play a role in partner choice for male yuhinas. Our study also highlights an important, but often neglected, question: Why do animals form non-kin groups, if kin are available? We use biological market theory to propose an explanation for group formation of unrelated Taiwan yuhinas. PMID:26086267

  20. Cluster-Derived Groupings of the Behavior Assessment System for Children among Male Juvenile Offenders

    ERIC Educational Resources Information Center

    Scarborough, Zane T.; Glaser, Brian A.; Calhoun, Georgia B.; Stefurak, Tres; Petrocelli, John V.

    2004-01-01

    Examined the cluster-derived typologies of males in a juvenile offender sample. Adolescent males, age 12-17, in a regional youth detention center were given the Behavior Assessment System for Children-Self Report-Adolescent (BASC-SRP-A; C. Reynolds &R. Kamphaus, 1992) and the Millon Adolescent Clinical Inventory (MACI; T. Millon, 1993).…

  1. An Alien in the Group: Eusocial Male Bees Sharing Nonspecific Reproductive Aggregations

    PubMed Central

    dos Santos, C. F.; Ferreira-Caliman, M. J.; Nascimento, F. S.

    2015-01-01

    Sexual selection predicts that individuals competing for access to sexual partners should maximize their chances of mating by looking for sites where the chances of finding partners are more likely to occur. However, males of stingless bees have been observed sharing nonspecific reproductive aggregations. This uncommon behavior appears to confer no obvious increase of individual fitness. It has been suggested that this reproductive strategy is due to the similarity between male odors common to different stingless bee species. Cuticular hydrocarbons (CHCs) are candidate odors of interest because their nonvolatile pheromone nature allows them to play an important role in sexual behavior and species recognition. Here, we review the literature to evaluate whether any phylogenetic patterns exist among male stingless bees that aggregate with closely or distantly related species. We also compared the CHC profiles of males of Neotropical stingless bee species (Plebeia sp. Schwarz, Trigona spinipes (F.), Tetragona clavipes (F.), Nannotrigona testaceicornis (Lepeletier), Scaptotrigona aff. depilis (Moure), Tetragonisca angustula (Latreille), and Melipona subnitida (Ducke) to reveal any chemical similarities among their male odors. We found males of 21 stingless bee species involved in interspecific interactions mainly from Neotropical and Indo-Malayan/Australasian regions. Alien males did not necessarily visit host aggregations of closely related species. Furthermore, the CHC profiles of different studied species were very distinct from each other and do not overlapped at all. It is unclear yet why this apparently nonadaptive behavior carried out by some stingless bee males. PMID:26518220

  2. The Influence of Social Comparison and Peer Group Size on Risky Decision-Making.

    PubMed

    Wang, Dawei; Zhu, Liping; Maguire, Phil; Liu, Yixin; Pang, Kaiyuan; Li, Zhenying; Hu, Yixin

    2016-01-01

    This study explores the influence of different social reference points and different comparison group sizes on risky decision-making. Participants were presented with a scenario describing an exam, and presented with the opportunity of making a risky decision in the context of different information provided about the performance of their peers. We found that behavior was influenced, not only by comparison with peers, but also by the size of the comparison group. Specifically, the larger the reference group, the more polarized the behavior it prompted. In situations describing social loss, participants were led to make riskier decisions after comparing themselves against larger groups, while in situations describing social gain, they become more risk averse. These results indicate that decision making is influenced both by social comparison and the number of people making up the social reference group. PMID:27582723

  3. The Influence of Social Comparison and Peer Group Size on Risky Decision-Making

    PubMed Central

    Wang, Dawei; Zhu, Liping; Maguire, Phil; Liu, Yixin; Pang, Kaiyuan; Li, Zhenying; Hu, Yixin

    2016-01-01

    This study explores the influence of different social reference points and different comparison group sizes on risky decision-making. Participants were presented with a scenario describing an exam, and presented with the opportunity of making a risky decision in the context of different information provided about the performance of their peers. We found that behavior was influenced, not only by comparison with peers, but also by the size of the comparison group. Specifically, the larger the reference group, the more polarized the behavior it prompted. In situations describing social loss, participants were led to make riskier decisions after comparing themselves against larger groups, while in situations describing social gain, they become more risk averse. These results indicate that decision making is influenced both by social comparison and the number of people making up the social reference group. PMID:27582723

  4. Female alternative reproductive behaviors: the effect of female group size on mate assessment and copying.

    PubMed

    Brennan, Bernard J; Flaxman, Samuel M; Alonzo, Suzanne H

    2008-08-01

    Extensive theoretical and empirical research has focused on male alternative reproductive tactics. In comparison, female alternative tactics have attracted little attention, and further theoretical and empirical research are needed. Using a game theoretical model, we examine female choice alternatives (1) by considering assessment errors in a novel and more realistic manner than done previously, and (2) for the first time, by highlighting the formation of groups of females as an important consequence of copying behavior. We consider two alternatives: direct assessment of male quality by females and female copying of the choice of other females. Assessment and copying are predicted to coexist under a wide variety of circumstances and copying is favored when females make assessment errors, when high-quality males are either common or very rare, and when female fitness declines with the number of other females choosing the same male. We also find that the frequency of copying at equilibrium is predicted to decrease when the presence of other females mating with the same male has a positive effect on female fitness (e.g. through increased male parental effort, decreased predation risk or cooperation among females). Female alternative choice tactics also influence the potential for sexual selection. In our model, when the frequency of copying females is low, the potential for sexual selection can be higher than in the absence of female copying. However, contrary to previous theory, we find that as copying females become more common than assessing females, the potential for sexual selection will be low as more females copy the mate choice of other copiers without assessment. PMID:18511084

  5. Stress-induced oxytocin release and oxytocin cell number and size in prepubertal and adult male and female rats.

    PubMed

    Minhas, Sumeet; Liu, Clarissa; Galdamez, Josselyn; So, Veronica M; Romeo, Russell D

    2016-08-01

    Studies indicate that adolescent exposure to stress is a potent environmental factor that contributes to psychological and physiological disorders, though the mechanisms that mediate these dysfunctions are not well understood. Periadolescent animals display greater stress-induced hypothalamic-pituitary-adrenal (HPA) axis responses than adults, which may contribute to these vulnerabilities. In addition to the HPA axis, the hypothalamo-neurohypophyseal tract (HNT) is also activated in response to stress. In adults, stress activates this system resulting in secretion of oxytocin from neurons in the supraoptic (SON) and paraventricular (PVN) nuclei. However, it is currently unknown whether a similar or different response occurs in prepubertal animals. Given the influence of these hormones on a variety of emotional behaviors and physiological systems known to change as an animal transitions into adulthood, we investigated stress-induced HPA and HNT hormonal responses before and after stress, as well as the number and size of oxytocin-containing cells in the SON and PVN of prepubertal (30d) and adult (70d) male and female rats. Though we found the well-established protracted adrenocorticotropic hormone and corticosterone response in prepubertal males and females, only adult males and prepubertal females showed a significant stress-induced increase in plasma oxytocin levels. Moreover, though we found no pubertal changes in the number of oxytocin cells, we did find a pubertal-related increase in oxytocin somal size in both the SON and PVN of males and females. Taken together, these data indicate that neuroendocrine systems can show different patterns of stress reactivity before and after adolescent development and that these responses can be further modified by sex. Given the impact of these hormones on a variety of systems, it will be imperative to further explore these changes in hormonal stress reactivity and their role in adolescent health. PMID:26972154

  6. Genetic composition of social groups influences male aggressive behaviour and fitness in natural genotypes of Drosophila melanogaster

    PubMed Central

    Saltz, Julia B.

    2013-01-01

    Indirect genetic effects (IGEs) describe how an individual's behaviour—which is influenced by his or her genotype—can affect the behaviours of interacting individuals. IGE research has focused on dyads. However, insights from social networks research, and other studies of group behaviour, suggest that dyadic interactions are affected by the behaviour of other individuals in the group. To extend IGE inferences to groups of three or more, IGEs must be considered from a group perspective. Here, I introduce the ‘focal interaction’ approach to study IGEs in groups. I illustrate the utility of this approach by studying aggression among natural genotypes of Drosophila melanogaster. I chose two natural genotypes as ‘focal interactants’: the behavioural interaction between them was the ‘focal interaction’. One male from each focal interactant genotype was present in every group, and I varied the genotype of the third male—the ‘treatment male’. Genetic variation in the treatment male's aggressive behaviour influenced the focal interaction, demonstrating that IGEs in groups are not a straightforward extension of IGEs measured in dyads. Further, the focal interaction influenced male mating success, illustrating the role of IGEs in behavioural evolution. These results represent the first manipulative evidence for IGEs at the group level. PMID:24068359

  7. Sample Size under Inverse Negative Binomial Group Testing for Accuracy in Parameter Estimation

    PubMed Central

    Montesinos-López, Osval Antonio; Montesinos-López, Abelardo; Crossa, José; Eskridge, Kent

    2012-01-01

    Background The group testing method has been proposed for the detection and estimation of genetically modified plants (adventitious presence of unwanted transgenic plants, AP). For binary response variables (presence or absence), group testing is efficient when the prevalence is low, so that estimation, detection, and sample size methods have been developed under the binomial model. However, when the event is rare (low prevalence <0.1), and testing occurs sequentially, inverse (negative) binomial pooled sampling may be preferred. Methodology/Principal Findings This research proposes three sample size procedures (two computational and one analytic) for estimating prevalence using group testing under inverse (negative) binomial sampling. These methods provide the required number of positive pools (), given a pool size (k), for estimating the proportion of AP plants using the Dorfman model and inverse (negative) binomial sampling. We give real and simulated examples to show how to apply these methods and the proposed sample-size formula. The Monte Carlo method was used to study the coverage and level of assurance achieved by the proposed sample sizes. An R program to create other scenarios is given in Appendix S2. Conclusions The three methods ensure precision in the estimated proportion of AP because they guarantee that the width (W) of the confidence interval (CI) will be equal to, or narrower than, the desired width (), with a probability of . With the Monte Carlo study we found that the computational Wald procedure (method 2) produces the more precise sample size (with coverage and assurance levels very close to nominal values) and that the samples size based on the Clopper-Pearson CI (method 1) is conservative (overestimates the sample size); the analytic Wald sample size method we developed (method 3) sometimes underestimated the optimum number of pools. PMID:22457714

  8. Predator biomass, prey density, and species composition effects on group size in recruit coral reef fishes

    USGS Publications Warehouse

    DeMartini, Edward E.; Anderson, Todd W.; Friedlander, Alan M.; Beets, James P.

    2011-01-01

    Group incidence and size are described for recruit parrotfishes, wrasses, and damselfishes on Hawaiian reefs over 3 years (2006–2008) at sites spanning the archipelago (20–28°N, 155–177°W). Coral-poor and coral-rich areas were surveyed at sites with both low (Hawaii Island) and high (Midway Atoll) predator densities, facilitating examination of relations among predator and recruit densities, habitat, and group metrics. Predator and recruit densities varied spatially and temporally, with a sixfold range in total recruit densities among years. Group (≥2 recruits) metrics varied with time and tracked predator and recruit densities and the proportion of schooling species. Groups often included heterospecifics whose proportion increased with group size. A non-saturating relationship between group size and recruit density suggests that the anti-predator benefits of aggregation exceeded competitive costs. Grouping behavior may have overarching importance for recruit survival—even at high recruit densities—and merits further study on Hawaiian reefs and elsewhere.

  9. Relational diversity and neighbourhood cohesion. Unpacking variety, balance and in-group size.

    PubMed

    Koopmans, Ruud; Schaeffer, Merlin

    2015-09-01

    Ethnic diversity is typically measured by the well-known Hirschman-Herfindahl Index. This paper discusses the merits of an alternative approach, which is in our view better suited to tease out why and how ethnic diversity matters. The approach consists of two elements. First, all existing diversity indices are non-relational. From the viewpoint of theoretical accounts that attribute negative diversity effects to in-group favoritism and out-group threat, it should however matter whether, given a certain level of overall diversity, an individual belongs to a minority group or to the dominant majority. We therefore decompose diversity by distinguishing the in-group share from the diversity of ethnic out-groups. Second, we show how generalized entropy measures can be used to test which of diversity's two basic dimensions matters most: the variety of groups, or the unequal distribution (balance) of the population over groups. These measures allow us to test different theoretical explanations against each other, because they imply different expectations regarding the effects of in-group size, out-group variety, and out-group balance. We apply these ideas in an analysis of various social cohesion measures across 55 German localities and show that both in-group size and out-group diversity matter. For the native majority as well as for persons of immigration background, the variety component of diversity seems to be more decisive than has formerly been acknowledged. These findings provide little support for group threat and in-group favoritism as the decisive mechanisms behind negative diversity effects, and are most in line with the predictions of theories that emphasize coordination problems, asymmetric preferences, and network closure. PMID:26188445

  10. Nitrogen limitation as a driver of genome size evolution in a group of karst plants.

    PubMed

    Kang, Ming; Wang, Jing; Huang, Hongwen

    2015-01-01

    Genome size is of fundamental biological importance with significance in predicting structural and functional attributes of organisms. Although abundant evidence has shown that the genome size can be largely explained by differential proliferation and removal of non-coding DNA of the genome, the evolutionary and ecological basis of genome size variation remains poorly understood. Nitrogen (N) and phosphorus (P) are essential elements of DNA and protein building blocks, yet often subject to environmental limitation in natural ecosystems. Using phylogenetic comparative methods, we test this hypothesis by determining whether leaf N and P availability affects genome sizes in 99 species of Primulina (Gesneriaceae), a group of soil specialists adapted to limestone karst environment in south China. We find that genome sizes in Primulina are strongly positively correlated with plant N content, but the correlation with plant P content is not significant when phylogeny history was taken into account. This study shows for the first time that N limitation might have been a plausible driver of genome size variation in a group of plants. We propose that competition for nitrogen nutrient between DNA synthesis and cellular functions is a possible mechanism for genome size evolution in Primulina under N-limitation. PMID:26109237

  11. Nitrogen limitation as a driver of genome size evolution in a group of karst plants

    PubMed Central

    Kang, Ming; Wang, Jing; Huang, Hongwen

    2015-01-01

    Genome size is of fundamental biological importance with significance in predicting structural and functional attributes of organisms. Although abundant evidence has shown that the genome size can be largely explained by differential proliferation and removal of non-coding DNA of the genome, the evolutionary and ecological basis of genome size variation remains poorly understood. Nitrogen (N) and phosphorus (P) are essential elements of DNA and protein building blocks, yet often subject to environmental limitation in natural ecosystems. Using phylogenetic comparative methods, we test this hypothesis by determining whether leaf N and P availability affects genome sizes in 99 species of Primulina (Gesneriaceae), a group of soil specialists adapted to limestone karst environment in south China. We find that genome sizes in Primulina are strongly positively correlated with plant N content, but the correlation with plant P content is not significant when phylogeny history was taken into account. This study shows for the first time that N limitation might have been a plausible driver of genome size variation in a group of plants. We propose that competition for nitrogen nutrient between DNA synthesis and cellular functions is a possible mechanism for genome size evolution in Primulina under N-limitation. PMID:26109237

  12. Nitrogen limitation as a driver of genome size evolution in a group of karst plants

    NASA Astrophysics Data System (ADS)

    Kang, Ming; Wang, Jing; Huang, Hongwen

    2015-06-01

    Genome size is of fundamental biological importance with significance in predicting structural and functional attributes of organisms. Although abundant evidence has shown that the genome size can be largely explained by differential proliferation and removal of non-coding DNA of the genome, the evolutionary and ecological basis of genome size variation remains poorly understood. Nitrogen (N) and phosphorus (P) are essential elements of DNA and protein building blocks, yet often subject to environmental limitation in natural ecosystems. Using phylogenetic comparative methods, we test this hypothesis by determining whether leaf N and P availability affects genome sizes in 99 species of Primulina (Gesneriaceae), a group of soil specialists adapted to limestone karst environment in south China. We find that genome sizes in Primulina are strongly positively correlated with plant N content, but the correlation with plant P content is not significant when phylogeny history was taken into account. This study shows for the first time that N limitation might have been a plausible driver of genome size variation in a group of plants. We propose that competition for nitrogen nutrient between DNA synthesis and cellular functions is a possible mechanism for genome size evolution in Primulina under N-limitation.

  13. Effect of group size on performance of growing-finishing pigs.

    PubMed

    Schmolke, S A; Li, Y Z; Gonyou, H W

    2003-04-01

    Six hundred forty growing-finishing pigs (initial BW = 23.2 +/- 4.8 kg) were used in a 12-wk study (final BW = 95.5 +/- 10.2 kg) to quantify the effects of group size (10, 20, 40, and 80 pigs/pen) on performance, tail biting, and use of widely distributed feed resources. One single-space wet/dry feeder was provided for every 10 pigs, and floor allowance was 0.76 m2/pig in all treatment groups. Weight gain and feed intake were measured every 2 wk. At weighing, a tail-biting injury score was given to each pig. Blood samples were collected and analyzed for neutrophil:lymphocyte ratio before regrouping at the beginning of the experiment, 24 to 48 h after regrouping, and on the last day of each trial. The use of feeders by individual pigs was assessed by behavioral observations. Average daily gain for the entire 12-wk trial did not differ among group sizes (861, 873, 854, and 845 g/d for groups of 10, 20, 40, and 80, respectively; P > 0.10). During the first 2 wk, ADG was lower for pigs in groups of 40 (554 g/d) than pigs in groups of 10 (632 g/d; P < 0.05), but not pigs in groups of 20 or 80 (602 and 605 g/d, respectively). Average daily feed intake, feed efficiency, and variability in final BW within a pen also did not differ among group sizes. Tail-biting injury scores increased throughout the study, but did not differ among group sizes. Similar proportions of pigs were removed from the trial for health reasons, primarily due to tail biting, in all treatments. Individual pigs in each group size ate from most, if not all, of the feeders in the pen. There was no evidence of spatial subgrouping within the larger groups. The results suggest that housing growing-finishing pigs in groups of up to 80 pigs is not detrimental to productivity and health if space allowance is adequate and feed resources are evenly distributed. PMID:12723074

  14. Modeling Group Size and Scalar Stress by Logistic Regression from an Archaeological Perspective

    PubMed Central

    Alberti, Gianmarco

    2014-01-01

    Johnson’s scalar stress theory, describing the mechanics of (and the remedies to) the increase in in-group conflictuality that parallels the increase in groups’ size, provides scholars with a useful theoretical framework for the understanding of different aspects of the material culture of past communities (i.e., social organization, communal food consumption, ceramic style, architecture and settlement layout). Due to its relevance in archaeology and anthropology, the article aims at proposing a predictive model of critical level of scalar stress on the basis of community size. Drawing upon Johnson’s theory and on Dunbar’s findings on the cognitive constrains to human group size, a model is built by means of Logistic Regression on the basis of the data on colony fissioning among the Hutterites of North America. On the grounds of the theoretical framework sketched in the first part of the article, the absence or presence of colony fissioning is considered expression of not critical vs. critical level of scalar stress for the sake of the model building. The model, which is also tested against a sample of archaeological and ethnographic cases: a) confirms the existence of a significant relationship between critical scalar stress and group size, setting the issue on firmer statistical grounds; b) allows calculating the intercept and slope of the logistic regression model, which can be used in any time to estimate the probability that a community experienced a critical level of scalar stress; c) allows locating a critical scalar stress threshold at community size 127 (95% CI: 122–132), while the maximum probability of critical scale stress is predicted at size 158 (95% CI: 147–170). The model ultimately provides grounds to assess, for the sake of any further archaeological/anthropological interpretation, the probability that a group reached a hot spot of size development critical for its internal cohesion. PMID:24626241

  15. Effect of Group-Selection Opening Size on Breeding Bird Habitat Use in a Bottomland Forest

    SciTech Connect

    Moorman, C.E.; D.C. Guynn, Jr.

    2001-12-01

    Research on the effects of creating group-selection openings of various sizes on breeding birds habitat use in a bottomland hardwood forest of the Upper Coastal Plain of South Carolina. Creation of 0.5-ha group selection openings in southern bottomland forests should provide breeding habitat for some field-edge species in gaps and habitat for forest-interior species and canopy-dwelling forest-edge species between gaps provided that enough mature forest is made available.

  16. Social structure mediates environmental effects on group size in an obligate cooperative breeder, Suricata suricatta.

    PubMed

    Bateman, A W; Ozgul, A; Nielsen, J F; Coulson, T; Clutton-Brock, T H

    2013-03-01

    Population dynamics in group-living species can be strongly affected both by features of sociality per se and by resultant population structure. To develop a mechanistic understanding of population dynamics in highly social species we need to investigate how processes within groups, processes linking groups, and external drivers act and interact to produce observed patterns. We model social group dynamics in cooperatively breeding meerkats, Suricata suricatta, paying attention to local demographic as well as dispersal processes. We use generalized additive models to describe the influence of group size, population density, and environmental conditions on demographic rates for each sex and stage, and we combine these models into predictive and individual-based simulation models of group dynamics. Short-term predictions of expected group size and simulated group trajectories over the longer term agree well with observations. Group dynamics are characterized by slow increases during the breeding season and relatively sharp declines during the pre-breeding season, particularly after dry years. We examine the demographic mechanisms responsible for environmental dependence. While individuals appear more prone to emigrate after dry years, seasons of low rainfall also cause reductions in reproductive output that produce adult-biased age distributions in the following dispersal season. Adult subordinates are much more likely to disperse or be evicted than immature individuals, and demographic structure thus contributes to crashes in group size. Our results demonstrate the role of social structure in characterizing a population's response to environmental variation. We discuss the implications of our findings for the population dynamics of cooperative breeders and population dynamics generally. PMID:23687885

  17. Effect of group size on behavior, health, production, and welfare of veal calves.

    PubMed

    Abdelfattah, E M; Schutz, M M; Lay, D C; Marchant-Forde, J N; Eicher, S D

    2013-11-01

    The objective of this study was to investigate the effect of group size on behavior, growth, health, and welfare of veal calves. Holstein-Friesian bull calves (n=168; 44±3 d of age) were assigned randomly to 1 of 3 treatments of group housing with 2, 4, or 8 calves per pen. The pens used for housing were 3 by 1.20 m (2 calves per pen), 3 by 2.40 m (4 calves per pen), and 3 by 4.80 m (8 calves per pen), supplying a total pen space allowance of 1.82 m2/calf, regardless of pen size. Behavior was recorded from video data throughout the day from 0700 to 1900 h during a single day each month for 5 mo using scan sampling every 5 min within 30-min observation sessions. On d 0, 1, 5, 14, 42, and 70 after grouping, continuous focal sampling around feeding time (30-min intervals before, during, and after feeding) focused on oral and aggressive behaviors. Calves housed in large groups (4 or 8 calves per pen) showed more (P≤0.001) conspecific contact, walking, and standing and less (P<0.001) manipulation of objects, self-licking, and lying when compared to calves housed in small groups (2 calves per pen). Group size had no effect on play behavior (P=0.11) throughout the experiment. During feeding times group size had no (P≥0.07) effect on any behavioral patterns except for duration of conspecific contact (P<0.01). Aggression at feeding time was not (P>0.23) affected by treatment. Group size treatments were similar for hip height change (P=0.41) and heart girth change (P=0.18) over the duration of the experiment; however, both hip height and heart girth increased (P=0.001) with calf age. During mo 1, calves in groups of 8 or 4 coughed more than calves in groups of 2 whereas calves in groups of 8 coughed more than calves in groups of 4 or 2 in mo 2 (treatment×month, P=0.03). Furthermore, during mo 4, calves in groups of 8 had less nasal discharge than calves in groups of 2 or 4 (treatment×month, P=0.02). Ocular discharge, ears, and fecal scores did not differ (P≥0

  18. Effect of Habitat Size, Quality, and Isolation on Functional Groups of Beetles in Hollow Oaks

    PubMed Central

    Pilskog, Hanne Eik; Birkemoe, Tone; Framstad, Erik; Sverdrup-Thygeson, Anne

    2016-01-01

    One of the largest threats to biodiversity is land use change and habitat loss. Hollow oaks (Quercus spp. L.) are well-defined patches that are hotspots for biodiversity and red-listed species, but they are often rare and fragmented in the landscape. We investigated the effect of patch size, habitat quality, and isolation on functional groups and red-listed saproxylic beetles in hollow oaks (n = 40) in Norway. The groups were defined by host tree association, trophic grouping, and red-listed status. Habitat quality, represented by tree form was most important in explaining species richness for most groups. Patch size, represented by circumference and amount of dead branches, was most important in explaining abundance. Isolation, that is single oaks compared with oaks in groups, had a negative effect on the abundance of beetles feeding both on wood and fungi (xylomycethopagous), as well as on species associated with broadleaved trees (oak semi-specialists), but did not affect species richness. This indicates that at this scale and in this landscape, isolated oaks are as species rich and valuable for conservation as other oaks, although some functional groups may be more vulnerable to isolation than others. The red-listed species only responded to patch size, indicating that oaks with large circumference and many dead branches are especially important for red-listed species and for conservation. PMID:26945089

  19. Effect of Habitat Size, Quality, and Isolation on Functional Groups of Beetles in Hollow Oaks.

    PubMed

    Pilskog, Hanne Eik; Birkemoe, Tone; Framstad, Erik; Sverdrup-Thygeson, Anne

    2016-01-01

    One of the largest threats to biodiversity is land use change and habitat loss. Hollow oaks (Quercus spp. L.) are well-defined patches that are hotspots for biodiversity and red-listed species, but they are often rare and fragmented in the landscape. We investigated the effect of patch size, habitat quality, and isolation on functional groups and red-listed saproxylic beetles in hollow oaks (n = 40) in Norway. The groups were defined by host tree association, trophic grouping, and red-listed status. Habitat quality, represented by tree form was most important in explaining species richness for most groups. Patch size, represented by circumference and amount of dead branches, was most important in explaining abundance. Isolation, that is single oaks compared with oaks in groups, had a negative effect on the abundance of beetles feeding both on wood and fungi (xylomycethopagous), as well as on species associated with broadleaved trees (oak semi-specialists), but did not affect species richness. This indicates that at this scale and in this landscape, isolated oaks are as species rich and valuable for conservation as other oaks, although some functional groups may be more vulnerable to isolation than others. The red-listed species only responded to patch size, indicating that oaks with large circumference and many dead branches are especially important for red-listed species and for conservation. PMID:26945089

  20. Spatial-size scaling of pedestrian groups under growing density conditions

    NASA Astrophysics Data System (ADS)

    Zanlungo, Francesco; Brščić, Dražen; Kanda, Takayuki

    2015-06-01

    We study the dependence on crowd density of the spatial size, configuration, and velocity of pedestrian social groups. We find that, in the investigated density range, the extension of pedestrian groups in the direction orthogonal to that of motion decreases linearly with the pedestrian density around them, both for two- and three-person groups. Furthermore, we observe that at all densities, three-person groups walk slower than two-person groups, and the latter are slower than individual pedestrians, the differences in velocities being weakly affected by density. Finally, we observe that three-person groups walk in a V-shaped formation regardless of density, with a distance between the pedestrians in the front and back again almost independent of density, although the configuration appears to be less stable at higher densities. These findings may facilitate the development of more realistic crowd dynamics models and simulators.

  1. A Study of the Employment Problems and Prospects of a Selected Group of Male Occupationally Oriented High School Graduates.

    ERIC Educational Resources Information Center

    Plusch, James Oscar

    This study described 302 occupationally oriented 1963 male high school graduates in terms of their group mental ability and scholastic achievement, marital and military service status, vocational aspirations as high school seniors, revised vocational aspirations after at least 2 years of work experience, job turnover and unemployment, occupational…

  2. Proficiency Assessment of Male Volleyball Teams of the 13-15-Year Age Group at Estonian Championships

    ERIC Educational Resources Information Center

    Stamm, Meelis; Stamm, Raini; Koskel, Sade

    2008-01-01

    Study aim: Assessment of feasibility of using own computer software "Game" at competitions. Material and methods: The data were collected during Estonian championships in 2006 for male volleyball teams of the 13-15-years age group (n = 8). In all games, the performance of both teams was recorded in parallel with two computers. A total of 19 games…

  3. "You Have to Hold Your Own": Investigating the Social Networks of a Diverse Group of Disenfranchised Urban Male Youth

    ERIC Educational Resources Information Center

    Esposito, Jennifer; Happel, Alison

    2015-01-01

    This ethnographic case study investigates social networks and forms of social capital accessed by a group of five urban male youth (ages 15-19), from diverse racial backgrounds, who were disenfranchised economically. We refer to the youth as "disenfranchised" because they were disconnected from forms of institutional support, especially…

  4. Tooth Size in Patients with Mild, Moderate and Severe Hypodontia and a Control Group

    PubMed Central

    Khalaf, Khaled

    2016-01-01

    Objectives: To compare tooth size between subjects with mild, moderate and severe hypodontia and a control group. Material and Methods: The study comprised 120 patients with hypodontia divided into three groups of 40 mild (≤2 teeth congenitally missing), 40 moderate (3-5 teeth congenitally missing) and 40 severe (≥6 teeth congenitally missing) hypodontia; and 40 age and sex matched controls. Tooth size was recorded by measuring the mesiodistal and buccolingual dimensions of all fully erupted teeth on study models using digital callipers and compared between all hypodontia and control groups using Two-way ANOVA and Post Hoc Tests of subgroup comparison. Results: Two-way ANOVA revealed patients with hypodontia had significantly smaller mesiodistal and buccolingual tooth dimensions compared with controls (p<0.05). Furthermore patients with more severe hypodontia demonstrated significantly smaller tooth dimensions than those in the mild and moderate hypodontia subgroups (p<0.05). The most affected tooth in terms of tooth size reduction was the maxillary lateral incisor and the least affected tooth was the mandibular first molar. Conclusion: Patients with hypodontia have smaller tooth dimensions than control. Tooth size appears to be affected by the degree of hypodontia, with severe hypodontia having a greater effect on tooth size reduction. The findings of this study may contribute to understanding the aetiology of hypodontia and aid the multidisciplinary management of this complex condition. PMID:27583048

  5. Blood thicker than water: kinship, disease prevalence and group size drive divergent patterns of infection risk in a social mammal

    PubMed Central

    Delahay, Richard J.

    2016-01-01

    The importance of social- and kin-structuring of populations for the transmission of wildlife disease is widely assumed but poorly described. Social structure can help dilute risks of transmission for group members, and is relatively easy to measure, but kin-association represents a further level of population sub-structure that is harder to measure, particularly when association behaviours happen underground. Here, using epidemiological and molecular genetic data from a wild, high-density population of the European badger (Meles meles), we quantify the risks of infection with Mycobacterium bovis (the causative agent of tuberculosis) in cubs. The risk declines with increasing size of its social group, but this net dilution effect conceals divergent patterns of infection risk. Cubs only enjoy reduced risk when social groups have a higher proportion of test-negative individuals. Cubs suffer higher infection risk in social groups containing resident infectious adults, and these risks are exaggerated when cubs and infectious adults are closely related. We further identify key differences in infection risk associated with resident infectious males and females. We link our results to parent–offspring interactions and other kin-biased association, but also consider the possibility that susceptibility to infection is heritable. These patterns of infection risk help to explain the observation of a herd immunity effect in badgers following low-intensity vaccination campaigns. They also reveal kinship and kin-association to be important, and often hidden, drivers of disease transmission in social mammals. PMID:27440666

  6. Group size, cage shelf level, and emotionality in non-obese diabetic mice: impact on onset and incidence of IDDM.

    PubMed

    Ader, D N; Johnson, S B; Huang, S W; Riley, W J

    1991-01-01

    We hypothesized that differential housing, shown to influence emotionality and health in infectious and neoplastic disease, would influence onset/incidence of diabetes in an autoimmune animal model of insulin-dependent diabetes mellitus (IDDM). Non-obese diabetic mice were assigned to same-sex groups of one, five, or eight animals/cage, counterbalanced across shelf level by sex and group. During weekly urine glucose testing, presence of behaviors indicating emotional arousal was recorded. Sex, group, and shelf level affected emotionality: males, animals housed alone, and those on the top of the rack exhibited higher emotionality. Emotionality and shelf level predicted IDDM in females only. Delayed onset of IDDM was associated with high emotionality and with being housed on the top of the rack. Group size had no significant effect on IDDM. Emotionality may be a mediating factor in animals genetically predisposed to develop IDDM. This variable and cage shelf level should be incorporated into the design of studies in which IDDM is the outcome. PMID:1882012

  7. Blood thicker than water: kinship, disease prevalence and group size drive divergent patterns of infection risk in a social mammal.

    PubMed

    Benton, Clare H; Delahay, Richard J; Robertson, Andrew; McDonald, Robbie A; Wilson, Alastair J; Burke, Terry A; Hodgson, Dave

    2016-07-27

    The importance of social- and kin-structuring of populations for the transmission of wildlife disease is widely assumed but poorly described. Social structure can help dilute risks of transmission for group members, and is relatively easy to measure, but kin-association represents a further level of population sub-structure that is harder to measure, particularly when association behaviours happen underground. Here, using epidemiological and molecular genetic data from a wild, high-density population of the European badger (Meles meles), we quantify the risks of infection with Mycobacterium bovis (the causative agent of tuberculosis) in cubs. The risk declines with increasing size of its social group, but this net dilution effect conceals divergent patterns of infection risk. Cubs only enjoy reduced risk when social groups have a higher proportion of test-negative individuals. Cubs suffer higher infection risk in social groups containing resident infectious adults, and these risks are exaggerated when cubs and infectious adults are closely related. We further identify key differences in infection risk associated with resident infectious males and females. We link our results to parent-offspring interactions and other kin-biased association, but also consider the possibility that susceptibility to infection is heritable. These patterns of infection risk help to explain the observation of a herd immunity effect in badgers following low-intensity vaccination campaigns. They also reveal kinship and kin-association to be important, and often hidden, drivers of disease transmission in social mammals. PMID:27440666

  8. INFLUENCE OF SPAWNING GROUP SIZE AND SPACE ON REPRODUCTION BY SHEEPSHEAD MINNOWS, CYPRINODON VARIEGATUS

    EPA Science Inventory

    Cripe, G.M., R.L. Hemmer and L.R. Goodman. In press. Influence of Spawning Group Size and Space on Reproduction Variability of Sheepshead Minnows, Cyprinodon variegatus (Abstract). To be presented at the SETAC Fourth World Congress, 14-18 November 2004, Portland, OR. 1 p. (ERL,GB...

  9. The Relationships among Group Size, Participation, and Performance of Programming Language Learning Supported with Online Forums

    ERIC Educational Resources Information Center

    Shaw, Ruey-Shiang

    2013-01-01

    This study examined the relationships among group size, participation, and learning performance factors when learning a programming language in a computer-supported collaborative learning (CSCL) context. An online forum was used as the CSCL environment for learning the Microsoft ASP.NET programming language. The collaborative-learning experiment…

  10. Group Size and Organisational Conditions for Children's Learning in Preschool: A Teacher Perspective

    ERIC Educational Resources Information Center

    Sheridan, Sonja; Williams, Pia; Pramling Samuelsson, Ingrid

    2014-01-01

    Background: There is a limited amount of research about group size in preschool, and how it impacts on teachers' working conditions and their ability to support children's learning and knowledge development in line with curriculum intentions. Purpose: From a perspective on quality, this article examines the organisational conditions for…

  11. What about N? A methodological study of sample-size reporting in focus group studies

    PubMed Central

    2011-01-01

    Background Focus group studies are increasingly published in health related journals, but we know little about how researchers use this method, particularly how they determine the number of focus groups to conduct. The methodological literature commonly advises researchers to follow principles of data saturation, although practical advise on how to do this is lacking. Our objectives were firstly, to describe the current status of sample size in focus group studies reported in health journals. Secondly, to assess whether and how researchers explain the number of focus groups they carry out. Methods We searched PubMed for studies that had used focus groups and that had been published in open access journals during 2008, and extracted data on the number of focus groups and on any explanation authors gave for this number. We also did a qualitative assessment of the papers with regard to how number of groups was explained and discussed. Results We identified 220 papers published in 117 journals. In these papers insufficient reporting of sample sizes was common. The number of focus groups conducted varied greatly (mean 8.4, median 5, range 1 to 96). Thirty seven (17%) studies attempted to explain the number of groups. Six studies referred to rules of thumb in the literature, three stated that they were unable to organize more groups for practical reasons, while 28 studies stated that they had reached a point of saturation. Among those stating that they had reached a point of saturation, several appeared not to have followed principles from grounded theory where data collection and analysis is an iterative process until saturation is reached. Studies with high numbers of focus groups did not offer explanations for number of groups. Too much data as a study weakness was not an issue discussed in any of the reviewed papers. Conclusions Based on these findings we suggest that journals adopt more stringent requirements for focus group method reporting. The often poor and

  12. Group Size Effect on Cooperation in One-Shot Social Dilemmas II: Curvilinear Effect.

    PubMed

    Capraro, Valerio; Barcelo, Hélène

    2015-01-01

    In a world in which many pressing global issues require large scale cooperation, understanding the group size effect on cooperative behavior is a topic of central importance. Yet, the nature of this effect remains largely unknown, with lab experiments insisting that it is either positive or negative or null, and field experiments suggesting that it is instead curvilinear. Here we shed light on this apparent contradiction by considering a novel class of public goods games inspired to the realistic scenario in which the natural output limits of the public good imply that the benefit of cooperation increases fast for early contributions and then decelerates. We report on a large lab experiment providing evidence that, in this case, group size has a curvilinear effect on cooperation, according to which intermediate-size groups cooperate more than smaller groups and more than larger groups. In doing so, our findings help fill the gap between lab experiments and field experiments and suggest concrete ways to promote large scale cooperation among people. PMID:26182247

  13. Species differences in group size and electrosensory interference in weakly electric fishes: implications for electrosensory processing.

    PubMed

    Stamper, Sarah A; Carrera-G, Erika; Tan, Eric W; Fugère, Vincent; Krahe, Rüdiger; Fortune, Eric S

    2010-03-01

    In animals with active sensory systems, group size can have dramatic effects on the sensory information available to individuals. In "wave-type" weakly electric fishes there is a categorical difference in sensory processing between solitary fish and fish in groups: when conspecifics are within about 1m of each other, the electric fields mix and produce interference patterns that are detected by electroreceptors on each individual. Neural circuits in these animals must therefore process two streams of information-salient signals from prey items and predators and social signals from nearby conspecifics. We investigated the parameters of social signals in two genera of sympatric weakly electric fishes, Apteronotus and Sternopygus, in natural habitats of the Napo River valley in Ecuador and in laboratory settings. Apteronotus were most commonly found in pairs along the Napo River (47% of observations; maximum group size 4) and produced electrosensory interference at rates of 20-300 Hz. In contrast, Sternopygus were alone in 80% of observations (maximum group size 2) in the same region of Ecuador. Similar patterns were observed in laboratory experiments: Apteronotus were in groups and preferentially approached conspecific-like signals in an electrotaxis experiment whereas Sternopygus tended to be solitary and did not approach conspecific-like electrosensory signals. These results demonstrate categorical differences in social electrosensory-related activation of central nervous system circuits that may be related to the evolution of the jamming avoidance response that is used in Apteronotus but not Sternopygus to increase the frequency of electrosensory interference patterns. PMID:19874855

  14. Group-size effects on the evolution of cooperation in the spatial public goods game

    NASA Astrophysics Data System (ADS)

    Szolnoki, Attila; Perc, Matjaž

    2011-10-01

    We study the evolution of cooperation in public goods games on the square lattice, focusing on the effects that are brought about by different sizes of groups where individuals collect their payoffs and search for potential strategy donors. We find that increasing the group size does not necessarily lead to mean-field behavior, as is traditionally observed for games governed by pairwise interactions, but rather that public cooperation may be additionally promoted by means of enhanced spatial reciprocity that sets in for very large groups. Our results highlight that the promotion of cooperation due to spatial interactions is not rooted solely in having restricted connections among players, but also in individuals having the opportunity to collect payoffs separately from their direct opponents. Moreover, in large groups the presence of a small number of defectors is bearable, which makes the mixed-phase region expand with increasing group size. Having a chance of exploiting distant players, however, offers defectors a different way to break the phalanx of cooperators and even to resurrect from small numbers to eventually completely invade the population.

  15. Group Size Effect on Cooperation in One-Shot Social Dilemmas II: Curvilinear Effect

    PubMed Central

    Capraro, Valerio; Barcelo, Hélène

    2015-01-01

    In a world in which many pressing global issues require large scale cooperation, understanding the group size effect on cooperative behavior is a topic of central importance. Yet, the nature of this effect remains largely unknown, with lab experiments insisting that it is either positive or negative or null, and field experiments suggesting that it is instead curvilinear. Here we shed light on this apparent contradiction by considering a novel class of public goods games inspired to the realistic scenario in which the natural output limits of the public good imply that the benefit of cooperation increases fast for early contributions and then decelerates. We report on a large lab experiment providing evidence that, in this case, group size has a curvilinear effect on cooperation, according to which intermediate-size groups cooperate more than smaller groups and more than larger groups. In doing so, our findings help fill the gap between lab experiments and field experiments and suggest concrete ways to promote large scale cooperation among people. PMID:26182247

  16. Male Reproductive Health After Childhood, Adolescent, and Young Adult Cancers: A Report From the Children's Oncology Group

    PubMed Central

    Kenney, Lisa B.; Cohen, Laurie E.; Shnorhavorian, Margarett; Metzger, Monika L.; Lockart, Barbara; Hijiya, Nobuko; Duffey-Lind, Eileen; Constine, Louis; Green, Daniel; Meacham, Lillian

    2012-01-01

    The majority of children, adolescents, and young adults diagnosed with cancer will become long-term survivors. Although cancer therapy is associated with many adverse effects, one of the primary concerns of young male cancer survivors is reproductive health. Future fertility is often the focus of concern; however, it must be recognized that all aspects of male health, including pubertal development, testosterone production, and sexual function, can be impaired by cancer therapy. Although pretreatment strategies to preserve reproductive health have been beneficial to some male patients, many survivors remain at risk for long-term reproductive complications. Understanding risk factors and monitoring the reproductive health of young male survivors are important aspects of follow-up care. The Children's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancer (COG-LTFU Guidelines) were created by the COG to provide recommendations for follow-up care of survivors at risk for long-term complications. The male health task force of the COG-LTFU Guidelines, composed of pediatric oncologists, endocrinologists, nurse practitioners, a urologist, and a radiation oncologist, is responsible for updating the COG-LTFU Guidelines every 2 years based on literature review and expert consensus. This review summarizes current task force recommendations for the assessment and management of male reproductive complications after treatment for childhood, adolescent, and young adult cancers. Issues related to male health that are being investigated, but currently not included in the COG-LTFU Guidelines, are also discussed. Ongoing investigation will inform future COG-LTFU Guideline recommendations for follow-up care to improve health and quality of life for male survivors. PMID:22649147

  17. Exploring Family Factors and Sexual Behaviors in a Group of Black and Hispanic Adolescent Males.

    ERIC Educational Resources Information Center

    Rucibwa, Naphtal Kaberege; Modeste, Naomi; Montgomery, Susan; Fox, Curtis A.

    2003-01-01

    Examined family factors influencing sexual behavior among black and Hispanic adolescent males from San Bernardino County, California's 1996 Youth Survey. Family structure, parent sexual behaviors, and peer sexual norms closely associated with adolescent sexual attitudes and behaviors. Having a sibling who was a teen parent significantly associated…

  18. Influence of group size on the success of wolves hunting bison.

    PubMed

    MacNulty, Daniel R; Tallian, Aimee; Stahler, Daniel R; Smith, Douglas W

    2014-01-01

    An intriguing aspect of social foraging behaviour is that large groups are often no better at capturing prey than are small groups, a pattern that has been attributed to diminished cooperation (i.e., free riding) in large groups. Although this suggests the formation of large groups is unrelated to prey capture, little is known about cooperation in large groups that hunt hard-to-catch prey. Here, we used direct observations of Yellowstone wolves (Canis lupus) hunting their most formidable prey, bison (Bison bison), to test the hypothesis that large groups are more cooperative when hunting difficult prey. We quantified the relationship between capture success and wolf group size, and compared it to previously reported results for Yellowstone wolves hunting elk (Cervus elaphus), a prey that was, on average, 3 times easier to capture than bison. Whereas improvement in elk capture success levelled off at 2-6 wolves, bison capture success levelled off at 9-13 wolves with evidence that it continued to increase beyond 13 wolves. These results are consistent with the hypothesis that hunters in large groups are more cooperative when hunting more formidable prey. Improved ability to capture formidable prey could therefore promote the formation and maintenance of large predator groups, particularly among predators that specialize on such prey. PMID:25389760

  19. Influence of Group Size on the Success of Wolves Hunting Bison

    PubMed Central

    MacNulty, Daniel R.; Tallian, Aimee; Stahler, Daniel R.; Smith, Douglas W.

    2014-01-01

    An intriguing aspect of social foraging behaviour is that large groups are often no better at capturing prey than are small groups, a pattern that has been attributed to diminished cooperation (i.e., free riding) in large groups. Although this suggests the formation of large groups is unrelated to prey capture, little is known about cooperation in large groups that hunt hard-to-catch prey. Here, we used direct observations of Yellowstone wolves (Canis lupus) hunting their most formidable prey, bison (Bison bison), to test the hypothesis that large groups are more cooperative when hunting difficult prey. We quantified the relationship between capture success and wolf group size, and compared it to previously reported results for Yellowstone wolves hunting elk (Cervus elaphus), a prey that was, on average, 3 times easier to capture than bison. Whereas improvement in elk capture success levelled off at 2–6 wolves, bison capture success levelled off at 9–13 wolves with evidence that it continued to increase beyond 13 wolves. These results are consistent with the hypothesis that hunters in large groups are more cooperative when hunting more formidable prey. Improved ability to capture formidable prey could therefore promote the formation and maintenance of large predator groups, particularly among predators that specialize on such prey. PMID:25389760

  20. Effects of paternal phenotype and environmental variability on age and size at maturity in a male dimorphic mite

    NASA Astrophysics Data System (ADS)

    Smallegange, Isabel M.

    2011-04-01

    Investigating how the environment affects age and size at maturity of individuals is crucial to understanding how changes in the environment affect population dynamics through the biology of a species. Paternal phenotype, maternal, and offspring environment may crucially influence these traits, but to my knowledge, their combined effects have not yet been tested. Here, I found that in bulb mites ( Rhizoglyphus robini), maternal nutrition, offspring nutrition, and paternal phenotype (males are fighters, able to kill other mites, or benign scramblers) interactively affected offspring age and size at maturity. The largest effect occurred when both maternal and offspring nutrition was poor: in that case offspring from fighter sires required a significantly longer development time than offspring from scrambler sires. Investigating parental effects on the relationship between age and size at maturity revealed no paternal effects, and only for females was its shape influenced by maternal nutrition. Overall, this reaction norm was nonlinear. These non-genetic intergenerational effects may play a complex, yet unexplored role in influencing population fluctuations—possibly explaining why results from field studies often do not match theoretical predictions on maternal effects on population dynamics.

  1. Adult Male Mice Emit Context-Specific Ultrasonic Vocalizations That Are Modulated by Prior Isolation or Group Rearing Environment

    PubMed Central

    Ey, Elodie; Bellier, Ludovic; Aubin, Thierry; Bourgeron, Thomas; Granon, Sylvie

    2012-01-01

    Social interactions in mice are frequently analysed in genetically modified strains in order to get insight of disorders affecting social interactions such as autism spectrum disorders. Different types of social interactions have been described, mostly between females and pups, and between adult males and females. However, we recently showed that social interactions between adult males could also encompass cognitive and motivational features. During social interactions, rodents emit ultrasonic vocalizations (USVs), but it remains unknown if call types are differently used depending of the context and if they are correlated with motivational state. Here, we recorded the calls of adult C57BL/6J male mice in various behavioral conditions, such as social interaction, novelty exploration and restraint stress. We introduced a modulator for the motivational state by comparing males maintained in isolation and males maintained in groups before the experiments. Male mice uttered USVs in all social and non-social situations, and even in a stressful restraint context. They nevertheless emitted the most important number of calls with the largest diversity of call types in social interactions, particularly when showing a high motivation for social contact. For mice maintained in social isolation, the number of calls recorded was positively correlated with the duration of social contacts, and most calls were uttered during contacts between the two mice. This correlation was not observed in mice maintained in groups. These results open the way for a deeper understanding and characterization of acoustic signals associated with social interactions. They can also help evaluating the role of motivational states in the emission of acoustic signals. PMID:22238608

  2. The relative effects of group size on reading progress of older students with reading difficulties

    PubMed Central

    Wanzek, Jeanne; Wexler, Jade; Barth, Amy; Cirino, Paul T.; Fletcher, Jack; Romain, Melissa; Denton, Carolyn A.; Roberts, Greg; Francis, David

    2010-01-01

    This study reports findings on the relative effects from a yearlong secondary intervention contrasting large-group, small-group, and school-provided interventions emphasizing word study, vocabulary development, fluency, and comprehension with seventh- and eighth-graders with reading difficulties. Findings indicate that few statistically significant results or clinically significant gains were associated with group size or intervention. Findings also indicate that a significant acceleration of reading outcomes for seventh- and eighth-graders from high-poverty schools is unlikely to result from a 50 min daily class. Instead, the findings indicate, achieving this outcome will require more comprehensive models including more extensive intervention (e.g., more time, even smaller groups), interventions that are longer in duration (multiple years), and interventions that vary in emphasis based on specific students’ needs (e.g., increased focus on comprehension or word study). PMID:21072131

  3. Fewer but better: Proportionate size of the group affects evaluation of transgressive leaders.

    PubMed

    Travaglino, Giovanni A; Abrams, Dominic; Randsley de Moura, Georgina; Yetkili, Orkun

    2016-06-01

    A group may be badly affected if its leader transgresses important rules. Nonetheless, an emerging body of evidence suggests that in intergroup contexts, group members apply a double standard when judging ingroup leaders - They respond less punitively to transgressions by their leader than by non-leaders. In this article, two experiments investigated how proportionate ingroup size affects reactions to transgressive ingroup leaders. We demonstrate that ingroup leaders from larger, but not smaller, groups benefit from the double standard. The experiments testing the effects of two different types of transgressions (nepotistic favouritism and corruption, respectively) show that transgressive leaders from larger groups are evaluated more positively than both comparable non-leaders and leaders from smaller groups. In contrast, transgressive leaders from smaller groups are evaluated similarly to comparable transgressive non-leaders. Experiment 2 investigated a potential explanation for this phenomenon. Faced with a transgressive leader, members of a smaller group report greater embarrassment than do members of larger groups in relation to the leaders' actions. Implications of these findings and directions for future research are discussed. PMID:26334165

  4. 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

  5. The Role of Host Traits, Season and Group Size on Parasite Burdens in a Cooperative Mammal

    PubMed Central

    Viljoen, Hermien; Bennett, Nigel C.; Ueckermann, Edward A.; Lutermann, Heike

    2011-01-01

    The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted. PMID:22069481

  6. Acceptability of Medical Male Circumcision and Improved Instrument Sanitation Among a Traditionally Circumcising Group in East Africa

    PubMed Central

    Mbwambo, Jessie K.; DiClemente, Ralph J.

    2012-01-01

    By removing the foreskin, medical male circumcision (MMC) reduces female to male heterosexual HIV transmission by approximately 60 %. Traditional circumcision has higher rates of complications than MMC, and reports indicate unsanitized instruments are sometimes shared across groups of circumcision initiates. A geographically stratified, cluster survey of acceptability of MMC and improved instrument sanitation was conducted among 368 eligible Maasai participants in two Northern Districts of Tanzania. Most respondents had been circumcised in groups, with 56 % circumcised with a shared knife rinsed in water between initiates and 16 % circumcised with a knife not cleaned between initiates. Contrasting practice, 88 % preferred use of medical supplies for their sons’ circumcisions. Willingness to provide MMC to sons was 28 %; however, provided the contingency of traditional leadership support for MMC, this rose to 84 %. Future interventions to address circumcision safety, including traditional circumciser training and expansion of access to MMC, are discussed. PMID:22797931

  7. Acceptability of medical male circumcision and improved instrument sanitation among a traditionally circumcising group in East Africa.

    PubMed

    Siegler, Aaron J; Mbwambo, Jessie K; DiClemente, Ralph J

    2012-10-01

    By removing the foreskin, medical male circumcision (MMC) reduces female to male heterosexual HIV transmission by approximately 60 %. Traditional circumcision has higher rates of complications than MMC, and reports indicate unsanitized instruments are sometimes shared across groups of circumcision initiates. A geographically stratified, cluster survey of acceptability of MMC and improved instrument sanitation was conducted among 368 eligible Maasai participants in two Northern Districts of Tanzania. Most respondents had been circumcised in groups, with 56 % circumcised with a shared knife rinsed in water between initiates and 16 % circumcised with a knife not cleaned between initiates. Contrasting practice, 88 % preferred use of medical supplies for their sons' circumcisions. Willingness to provide MMC to sons was 28 %; however, provided the contingency of traditional leadership support for MMC, this rose to 84 %. Future interventions to address circumcision safety, including traditional circumciser training and expansion of access to MMC, are discussed. PMID:22797931

  8. Heart Rates of Male and Female Sprague–Dawley and Spontaneously Hypertensive Rats Housed Singly or in Groups

    PubMed Central

    Azar, Toni; Sharp, Jody; Lawson, David

    2011-01-01

    This study was conducted to confirm our previous reports that group housing lowered basal heart rate and various evoked heart-rate responses in Sprague–Dawley male and female rats and to extend these observations to spontaneously hypertensive rats. Heart rate data were collected by using radiotelemetry. Initially, group- and single-housed rats were evaluated in the same animal room at the same time. Under these conditions, group-housing did not decrease heart rate in undisturbed male and female rats of either strain compared with single-housed rats. Separate studies then were conducted to examine single-housed rats living in the room with only single-housed rats. When group-housed rats were compared with these single-housed rats, undisturbed heart rates were reduced significantly, confirming our previous reports for Sprague–Dawley rats. However, evoked heart rate responses to acute procedures were not reduced universally in group-housed rats compared with either condition of single housing. Responses to some procedures were reduced, but others were not affected or were significantly enhanced by group housing compared with one or both of the single-housing conditions. This difference may have been due, in part, to different sensory stimuli being evoked by the various procedures. In addition, the variables of sex and strain interacted with housing condition. Additional studies are needed to resolve the mechanisms by which evoked cardiovascular responses are affected by housing, sex, and strain. PMID:21439210

  9. Vigilance behaviour of the year-round territorial vicuña (Vicugna vicugna) outside the breeding season: influence of group size, social factors and distance to a water source.

    PubMed

    Torres, M Eugenia Mosca; Puig, Silvia; Novillo, Agustina; Ovejero, Ramiro

    2015-04-01

    We conducted focal observations of vicuña, a year-around territorial mammal, to compare vigilance behaviour between territorial and bachelor males outside the reproductive season. We hypothesized that the time spent vigilant would depend on male social status, considering the potential effects of several variables: sampling year, group size, distances to the nearest neighbour and to a vega (mountain wetland). We fit GLM models to assess how these variables, and their interactions, affected time allocation of territorial and bachelor males. We found non significant differences between territorial and bachelor males in the time devoted to vigilance behaviour. Vigilance of territorial males was influenced by the sampling year and the distance to the vega. In turn, vigilance in bachelor males was influenced mainly by the sampling year, the group size and the distance to the vega. Our results suggest that sampling year and distance to the vega are more important than social factors in conditioning the behaviour of male vicuñas, during the non-reproductive season. Future studies of behaviour in water-dependant ungulates, should consider the influence of water and forage availabilities, and the interactions between group size and other variables. PMID:25680329

  10. Opposite effects of male and female helpers on social tolerance and proactive prosociality in callitrichid family groups.

    PubMed

    Burkart, Judith M

    2015-01-01

    Across a broad variety of primate species (including lemurs, New World monkeys, Old World monkeys, and apes), proactive prosociality and social tolerance are linked to allomaternal care, reaching the highest levels in the cooperatively breeding callitrichid monkeys and humans. However, considerable variation exists within callitrichids, and the aim of this study was to identify factors that explain this variation. Male and female callitrichids pursue different reproductive strategies, leading males to play a more prominent role in allomothering. We thus hypothesised that prosociality and tolerance may be affected by group composition and sex differences. We analysed social tolerance and proactive prosociality data in 49 common marmosets and found that the number of female helpers in a group was negatively correlated with group-level prosociality and tolerance. At the individual level, rearing experience or age enhanced prosociality in male, but not in female helpers. These findings are consistent with the more ambivalent role of female helpers in infant rearing. Adding data from 5 cotton-top and 5 lion tamarins strengthened this pattern. The same factor which explains variation in prosociality and tolerance across primate species, i.e. allomaternal care, is therefore also linked to variation within common marmosets, and presumably callitrichid monkeys in general. PMID:25881136

  11. Universal size effects for populations in group-outcome decision-making problems

    NASA Astrophysics Data System (ADS)

    Borghesi, Christian; Hernández, Laura; Louf, Rémi; Caparros, Fabrice

    2013-12-01

    Elections constitute a paradigm of decision-making problems that have puzzled experts of different disciplines for decades. We study two decision-making problems, where groups make decisions that impact only themselves as a group. In both studied cases, participation in local elections and the number of democratic representatives at different scales (from local to national), we observe a universal scaling with the constituency size. These results may be interpreted as constituencies having a hierarchical structure, where each group of N agents, at each level of the hierarchy, is divided in about Nδ subgroups with δ≈1/3. Following this interpretation, we propose a phenomenological model of vote participation where abstention is related to the perceived link of an agent to the rest of the constituency and which reproduces quantitatively the observed data.

  12. Size-constraints on intonation groups in speech: Evidence of an independent syllable-count principle

    NASA Astrophysics Data System (ADS)

    Gilbert, Annie C.; Boucher, Victor J.

    2005-04-01

    This poster examines size-limits on intonation (F0) contours in spontaneous speech and presents the results of an experiment on a syllable-count principle, which is seen to constitute, irrespective of syntax, a factor restricting the length of F0 groups. Studies of various languages indicate a general tendency to restrict stress-groups in speech to four syllables or less. In languages were stress is not lexically coded (e.g., French), syntax is not a sufficient predictor of stress. The object was to determine whether these aspects of stress patterning also apply to tonal groups. Statistics are lacking with respect to the extent of F0 contours in speech. Pitch-extracting software was used to analyze the speech of 15 native speakers of French (20 minutes each). Initial results suggest an eight-syllable limit on tonal groups. Based on these statistics an experiment was conducted where 40 Ss read and repeated visually presented sentences containing major syntactic divisions (phrase boundaries) at different locations. There are two central findings: (1) phrase boundaries placed at different points in the sentence did not serve to predict tonal grouping; (2) even when the sentence structure offered the possibility of creating large tonal groups, Ss did not create contours exceeding an eight-syllable limit.

  13. Phosphatidyl alcohols: effect of head group size on domain forming properties and interactions with sterols.

    PubMed

    Jaikishan, Shishir; Björkbom, Anders; Slotte, J Peter

    2010-08-01

    In this study, we have examined the membrane properties and sterol interactions of phosphatidyl alcohols varying in the size of the alcohol head group coupled to the sn-3-linked phosphate. Phosphatidyl alcohols of interest were dipalmitoyl derivatives with methanol (DPPMe), ethanol (DPPEt), propanol (DPPPr), or butanol (DPPBu) head groups. The Phosphatidyl alcohols are biologically relevant, because they can be formed in membranes by the phospholipase D reaction in the presence of alcohol. The melting behavior of pure phosphatidyl alcohols and mixtures with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or cholesterol was assessed using high sensitivity differential scanning calorimetry (DSC). DPPMe had the highest melting temperature ( approximately 49 degrees C), whereas the other phosphatidyl alcohols had similar melting temperatures as DPPC ( approximately 40-41 degrees C). All phosphatidyl alcohols, except DPPMe, also showed good miscibility with DPPC. The effects of cholesterol on the melting behavior and membrane order in multilamellar bilayer vesicles were assessed using steady-state anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and DSC. The ordering effect of cholesterol in the fluid phase was lower for all phosphatidyl alcohols as compared to DPPC and decreased with increasing head group size. The formation of ordered domains containing the phosphatidyl alcohols in complex bilayer membranes was determined using fluorescence quenching of DPH or the sterol analogue cholesta-5,7,(11)-trien-3-beta-ol (CTL). The phosphatidyl alcohols did not appear to form sterol-enriched ordered domains, whereas DPPMe, DPPEt appeared to form ordered domains in the temperature window examined (10-50 degrees C). The partitioning of CTL into bilayer membranes containing phosphatidyl alcohols was to a small extent increased for DPPMe and DPPEt, but in general, sterol interactions were weak or unfavorable for the phosphatidyl alcohols. Our results show that the biophysical

  14. Investment in sensory structures, testis size, and wing coloration in males of a diurnal moth species: trade-offs or correlated growth?

    PubMed

    Shiel, Brett P; Sherman, Craig D H; Elgar, Mark A; Johnson, Tamara L; Symonds, Matthew R E

    2015-04-01

    For dioecious animals, reproductive success typically involves an exchange between the sexes of signals that provide information about mate location and quality. Typically, the elaborate, secondary sexual ornaments of males signal their quality, while females may signal their location and receptivity. In theory, the receptor structures that receive the latter signals may also become elaborate or enlarged in a way that ultimately functions to enhance mating success through improved mate location. The large, elaborate antennae of many male moths are one such sensory structure, and eye size may also be important in diurnal moths. Investment in these traits may be costly, resulting in trade-offs among different traits associated with mate location. For polyandrous species, such trade-offs may also include traits associated with paternity success, such as larger testes. Conversely, we would not expect this to be the case for monandrous species, where sperm competition is unlikely. We investigated these ideas by evaluating the relationship between investment in sensory structures (antennae, eye), testis, and a putative warning signal (orange hindwing patch) in field-caught males of the monandrous diurnal painted apple moth Teia anartoides (Lepidoptera: Lymantriidae) in southeastern Australia. As predicted for a monandrous species, we found no evidence that male moths with larger sensory structures had reduced investment in testis size. However, contrary to expectation, investment in sensory structures was correlated: males with relatively larger antennae also had relatively larger eyes. Intriguingly, also, the size of male orange hindwing patches was positively correlated with testis size. PMID:25937904

  15. Size variation of 0-group plaice: Are earlier influences on growth potential a contributing factor?

    NASA Astrophysics Data System (ADS)

    Fox, Clive J.; Targett, Timothy E.; Ciotti, Benjamin J.; de Kroon, Kasper; Hortsmeyer, Lena; Burrows, Michael T.

    2014-04-01

    Over a decade of sampling has shown that there are consistent differences in the sizes of 0-group plaice by late summer comparing 21 nursery sites on the Scottish west coast. However, when young fish were collected from two sites which produce particularly small and large fish and reared using a common garden design, growth rates between fish from the two sites were indistinguishable. Either there is little selection for fast or slow growth up to a few weeks post-settlement, or such effects do not persist sufficiently strongly to influence later growth. There were also no significant correlations between the time-series of fish size comparing sites, although within some sites there was evidence of inter-annual density-dependent effects. Any influences of offshore regional-scale factors, such as sea temperature or pelagic primary productivity on growth thus appear to be heavily modified by local conditions on the nursery grounds. The field observations combined with the experimental results lead us to conclude that the size 0-group plaice attain in late summer is mainly controlled by post-settlement habitat quality.

  16. The Size Advantage Model of Sex Allocation in the Protandrous Sex-Changer Crepidula fornicata: Role of the Mating System, Sperm Storage, and Male Mobility.

    PubMed

    Broquet, Thomas; Barranger, Audrey; Billard, Emmanuelle; Bestin, Anastasia; Berger, Rémy; Honnaert, Gaelle; Viard, Frédérique

    2015-09-01

    Sequential hermaphroditism is adaptive when the reproductive value of an individual varies with size or age, and this relationship differs between males and females. In this case, theory shows that the lifetime reproductive output of an individual is increased by changing sex (a hypothesis referred to as the size-advantage model). Sex-linked differences in size-fitness curves can stem from differential costs of reproduction, the mating system, and differences in growth and mortality between sexes. Detailed empirical data is required to disentangle the relative roles of each of these factors within the theory. Quantitative data are also needed to explore the role of sperm storage, which has not yet been considered with sequential hermaphrodites. Using experimental rearing and paternity assignment, we report relationships between size and reproductive success of Crepidula fornicata, a protandrous (male-first) gastropod. Male reproductive success increased with size due to the polygamous system and stacking behavior of the species, but females nonetheless had greater reproductive success than males of the same size, in agreement with the size-advantage theory. Sperm storage appeared to be a critical determinant of success for both sexes, and modeling the effect of sperm storage showed that it could potentially accelerate sex change in protandrous species. PMID:26655357

  17. Particle-Size-Grouping Model of Precipitation Kinetics in Microalloyed Steels

    NASA Astrophysics Data System (ADS)

    Xu, Kun; Thomas, Brian G.

    2012-03-01

    The formation, growth, and size distribution of precipitates greatly affects the microstructure and properties of microalloyed steels. Computational particle-size-grouping (PSG) kinetic models based on population balances are developed to simulate precipitate particle growth resulting from collision and diffusion mechanisms. First, the generalized PSG method for collision is explained clearly and verified. Then, a new PSG method is proposed to model diffusion-controlled precipitate nucleation, growth, and coarsening with complete mass conservation and no fitting parameters. Compared with the original population-balance models, this PSG method saves significant computation and preserves enough accuracy to model a realistic range of particle sizes. Finally, the new PSG method is combined with an equilibrium phase fraction model for plain carbon steels and is applied to simulate the precipitated fraction of aluminum nitride and the size distribution of niobium carbide during isothermal aging processes. Good matches are found with experimental measurements, suggesting that the new PSG method offers a promising framework for the future development of realistic models of precipitation.

  18. Group size effect on cooperation in one-shot social dilemmas.

    PubMed

    Barcelo, Hélène; Capraro, Valerio

    2015-01-01

    Social dilemmas are central to human society. Depletion of natural resources, climate protection, security of energy supply, and workplace collaborations are all examples of social dilemmas. Since cooperative behaviour in a social dilemma is individually costly, Nash equilibrium predicts that humans should not cooperate. Yet experimental studies show that people do cooperate even in anonymous one-shot interactions. In spite of the large number of participants in many modern social dilemmas, little is known about the effect of group size on cooperation. Does larger group size favour or prevent cooperation? We address this problem both experimentally and theoretically. Experimentally, we find that there is no general answer: it depends on the strategic situation. Specifically, we find that larger groups are more cooperative in the Public Goods game, but less cooperative in the N-person Prisoner's dilemma. Theoretically, we show that this behaviour is not consistent with either the Fehr &Schmidt model or (a one-parameter version of) the Charness &Rabin model, but it is consistent with the cooperative equilibrium model introduced by the second author. PMID:25605124

  19. Differences in social skills performance between institutionalized juvenile male offenders and a comparable group of boys without offence records.

    PubMed

    Spence, S H

    1981-09-01

    Eighteen institutionalized young male offenders and 18 boys without criminal records, comparable in terms of age, academic performance and social background, were videotaped during a five-minute standardized interview with a previously unknown adult. The videotapes were then subjected to a behavioural analysis of 13 responses which had previously been suggested to be important social skill components. The tapes were also shown to six independent judges who rated each tape in terms of social skills performance, social anxiety, friendliness, and employability. The offender group was found to differ significantly from the non-offender group in terms of the level of eye-contact, head movements, amount spoken, fiddling movements, and gross body movements. The offender group was also rated in significantly less favourably terms on the scales of social skills performance, social anxiety, and employability, compared to the non-offender groups. No significant difference was found in terms of friendliness ratings. Correlation analyses between the specific behavioural measures and the subjective rating scales revealed statistically significant associations between six of the 13 behavioural measures and one or more of the subjective rating scales. The provides some indication of the type of responses important in determining the impression made by adolescent male in an interview situation. PMID:7284650

  20. Genome size in Hieracium subgenus Hieracium (Asteraceae) is strongly correlated with major phylogenetic groups

    PubMed Central

    Chrtek, Jindřich; Zahradníček, Jaroslav; Krak, Karol; Fehrer, Judith

    2009-01-01

    Background and Aims Hieracium subgenus Hieracium is one of the taxonomically most intricate groups of vascular plants, due to polyploidy and a diversity of breeeding systems (sexuality vs. apomixis). The aim of the present study was to analyse nuclear genome size in a phylogenetic framework and to assess relationships between genome size and ploidy, breeding system and selected ecogeographic features. Methods Holoploid and monoploid genome sizes (C- and Cx-values) of 215 cultivated plants from 89 field populations of 42 so-called ‘basic’ Hieracium species were determined using propidium iodide flow cytometry. Chromosome counts were available for all analysed plants, and all plants were tested experimentally for their mode of reproduction (sexuality vs. apomixis). For constructing molecular phylogenetic trees, the external transcribed spacer region of nuclear ribosomal DNA was used. Key Results The mean 2C values differed up to 2·37-fold among different species (from 7·03 pg in diploid to 16·67 in tetraploid accessions). The 1Cx values varied 1·22-fold (between 3·51 and 4·34 pg). Variation in 1Cx values between conspecific (species in a broad sense) accessions ranged from 0·24% to 7·2%. Little variation (not exceeding the approximate measurement inaccurracy threshold of 3·5%) was found in 33 species, whereas variation higher than 3·5% was detected in seven species. Most of the latter may have a polytopic origin. Mean 1Cx values of the three cytotypes (2n, 3n and 4n) differed significantly (average of 3·93 pg in diploids, 3·82 pg in triploids and 3·78 pg in tetraploids) indicating downsizing of genomes in polyploids. The pattern of genome size variation correlated well with two major phylogenetic clades which were composed of species with western or eastern European origin. The monoploid genome size in the ‘western’ species was significantly lower than in the ‘eastern’ ones. Correlation of genome size with latitude, altitude and selected

  1. Relationship between Parenting and Cognitive Schemas in a Group of Male Adult Offenders

    PubMed Central

    Pellerone, Monica; Craparo, Giuseppe; Tornabuoni, Ylenia

    2016-01-01

    This work analyzes the correlation of retrospective ratings on parental binding with cognitive patterns in the inmates for property crimes. The participant group comprehended 248 adults men, including 130 marked out as offenders (the target group), aged between 19 and 70, currently serving sentences in the Cavadonna prison in Siracusa, and 118 marked out as non-offenders (the control group), aged between 20 and 70, living in Siracusa (Sicily). The instruments used were the Parental Bonding Instrument (PBI), and the Young Schema Questionnaire-3 (YSQ). The preliminary analysis showed a high percentage of offenders who experienced an affectionate constraint parenting. Offenders scored significantly higher than the non-offenders on the level of paternal control and the YSQ subscales. The study underlines the influence of maternal care on most of the cognitive schemas, and the role of father's control on the tendency to social isolation and defectiveness in the offenders. PMID:27014121

  2. Relationship between Parenting and Cognitive Schemas in a Group of Male Adult Offenders.

    PubMed

    Pellerone, Monica; Craparo, Giuseppe; Tornabuoni, Ylenia

    2016-01-01

    This work analyzes the correlation of retrospective ratings on parental binding with cognitive patterns in the inmates for property crimes. The participant group comprehended 248 adults men, including 130 marked out as offenders (the target group), aged between 19 and 70, currently serving sentences in the Cavadonna prison in Siracusa, and 118 marked out as non-offenders (the control group), aged between 20 and 70, living in Siracusa (Sicily). The instruments used were the Parental Bonding Instrument (PBI), and the Young Schema Questionnaire-3 (YSQ). The preliminary analysis showed a high percentage of offenders who experienced an affectionate constraint parenting. Offenders scored significantly higher than the non-offenders on the level of paternal control and the YSQ subscales. The study underlines the influence of maternal care on most of the cognitive schemas, and the role of father's control on the tendency to social isolation and defectiveness in the offenders. PMID:27014121

  3. Ambiguous response of lung lamellar bodies to sauna-like heat stress in two age groups of adult male rats.

    PubMed

    Heino, M E

    1980-06-01

    Two groups of adult male rats, aged 2.5 and 5 months, were exposed daily for 12 min to 65 degrees C for five successive periods a week for 6 weeks. Both age groups, and in particular the young one, repeatedly suffered from exhausting heat stress. Lung specimens from cardiac lobes were prepared for light- and electron-microscopy. A significnat increase was noted in the lung lamellar body number in the old test rats, on comparison with old ones employed as controls (p < 0.05). The young group was unresponsive. Consequently, stress induced by increased sympathetic activity is not always a direct stimulus, as had been thought earlier. It seems, at least where heat stress is concerned, that it is the age, weight, and systemic reactions which exercise a great influence upon lamellar body production, and may even overrule the role of sympathetic activity. PMID:7417113

  4. The Effect of Grouping by Formal Reasoning Ability, Formal Reasoning Ability Levels, Group Size, and Gender on Achievement in Laboratory Chemistry.

    ERIC Educational Resources Information Center

    Moody, Judith D.; Gifford, Vernon D.

    This study investigated the grouping effect on student achievement in a chemistry laboratory when homogeneous and heterogeneous formal reasoning ability, high and low levels of formal reasoning ability, group sizes of two and four, and homogeneous and heterogeneous gender were used for grouping factors. The sample consisted of all eight intact…

  5. Positioning a "Mature" Self in Interactive Practices: How Adolescent Males Negotiate "Physical Attraction" in Group Talk

    ERIC Educational Resources Information Center

    Korobov, Neill; Bamberg, Michael

    2004-01-01

    This article presents a discursive psychological approach in examining the ways that adolescent boys (ages 12-15 years) accomplish a sense of "maturity" by bringing off and managing certain features of "heterosexuality" in group interaction. We focus on and analyse moments when the boys negotiate implicit challenges, make evaluations and offer…

  6. The Effects of Instructional Grouping on the Mathematics Achievement of Female and Male Elementary Students.

    ERIC Educational Resources Information Center

    Saltzen, Jo An Alderman

    This research focused on an institutional structural process and its relationship to sex differences in mathematics achievement. Instructional grouping by class and school interacted with curriculum and achievement. The sample consisted of 906 students in grades kindergarten through sixth in two elementary schools. Results showed that primary…

  7. Caries Experience Differs between Females and Males across Age Groups in Northern Appalachia

    PubMed Central

    Shaffer, John R.; Leslie, Elizabeth J.; Feingold, Eleanor; Govil, Manika; McNeil, Daniel W.; Crout, Richard J.; Weyant, Robert J.; Marazita, Mary L.

    2015-01-01

    Sex disparities in dental caries have been observed across many populations, with females typically exhibiting higher prevalence and more affected teeth. In this study we assessed the sex disparities in two Northern Appalachian populations from West Virginia (WV, N = 1997) and Pennsylvania (PA, N = 1080) by comparing caries indices between males and females across four phases of dental development: primary dentition in children aged 1–5 years, mixed dentition in children aged 6–11 years, permanent dentition in adolescents aged 12–17 years, and permanent dentition in adults aged 18–59 years. No significant sex differences were observed for children aged 1–5 years. Contrary to national and international trends, WV girls aged 6–11 years had 1.5 fewer affected teeth than boys (p < 0.001). However, by ages 12–17, caries indices in the WV girls matched those in boys. In both WV and PA adults, women and men had similar total counts of affected teeth (i.e., DMFT), although women had more dental restorations (p < 0.001) and men had more current decay (p < 0.001). These results suggest that in some Appalachian populations, young girls benefit from protection against caries that is lost during adolescence and that adult women utilize dental health care to a greater degree than men. PMID:26106416

  8. Caries Experience Differs between Females and Males across Age Groups in Northern Appalachia.

    PubMed

    Shaffer, John R; Leslie, Elizabeth J; Feingold, Eleanor; Govil, Manika; McNeil, Daniel W; Crout, Richard J; Weyant, Robert J; Marazita, Mary L

    2015-01-01

    Sex disparities in dental caries have been observed across many populations, with females typically exhibiting higher prevalence and more affected teeth. In this study we assessed the sex disparities in two Northern Appalachian populations from West Virginia (WV, N = 1997) and Pennsylvania (PA, N = 1080) by comparing caries indices between males and females across four phases of dental development: primary dentition in children aged 1-5 years, mixed dentition in children aged 6-11 years, permanent dentition in adolescents aged 12-17 years, and permanent dentition in adults aged 18-59 years. No significant sex differences were observed for children aged 1-5 years. Contrary to national and international trends, WV girls aged 6-11 years had 1.5 fewer affected teeth than boys (p < 0.001). However, by ages 12-17, caries indices in the WV girls matched those in boys. In both WV and PA adults, women and men had similar total counts of affected teeth (i.e., DMFT), although women had more dental restorations (p < 0.001) and men had more current decay (p < 0.001). These results suggest that in some Appalachian populations, young girls benefit from protection against caries that is lost during adolescence and that adult women utilize dental health care to a greater degree than men. PMID:26106416

  9. The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder.

    PubMed

    Cram, Dominic L; Blount, Jonathan D; Young, Andrew J

    2015-11-22

    Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali. Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies. PMID:26582023

  10. The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder

    PubMed Central

    Cram, Dominic L.; Blount, Jonathan D.; Young, Andrew J.

    2015-01-01

    Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali. Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies. PMID:26582023

  11. A passive acoustic monitoring method applied to observation and group size estimation of finless porpoises.

    PubMed

    Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari; Li, Songhai; Xiao, Jianqiang

    2005-08-01

    The present study aimed at determining the detection capabilities of an acoustic observation system to recognize porpoises under local riverine conditions and compare the results with sighting observations. Arrays of three to five acoustic data loggers were stationed across the main channel of the Tian-e-zhou Oxbow of China's Yangtze River at intervals of 100-150 m to record sonar signals of free-ranging finless porpoises (Neophocaena phocaenoides). Acoustic observations, concurrent with visual observations, were conducted at two occasions on 20-22 October 2003 and 17-19 October 2004. During a total of 42 h of observation, 316 finless porpoises were sighted and 7041 sonar signals were recorded by loggers. The acoustic data loggers recorded ultrasonic signals of porpoises clearly, and detected the presence of porpoises with a correct detection level of 77.6% and a false alarm level of 5.8% within an effective distance of 150 m. Results indicated that the stationed passive acoustic observation method was effective in detecting the presence of porpoises and showed potential in estimating the group size. A positive linear correlation between the number of recorded signals and the group size of sighted porpoises was indicated, although it is faced with some uncertainty and requires further investigation. PMID:16158672

  12. A passive acoustic monitoring method applied to observation and group size estimation of finless porpoises

    NASA Astrophysics Data System (ADS)

    Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari; Li, Songhai; Xiao, Jianqiang

    2005-08-01

    The present study aimed at determining the detection capabilities of an acoustic observation system to recognize porpoises under local riverine conditions and compare the results with sighting observations. Arrays of three to five acoustic data loggers were stationed across the main channel of the Tian-e-zhou Oxbow of China's Yangtze River at intervals of 100-150 m to record sonar signals of free-ranging finless porpoises (Neophocaena phocaenoides). Acoustic observations, concurrent with visual observations, were conducted at two occasions on 20-22 October 2003 and 17-19 October 2004. During a total of 42 h of observation, 316 finless porpoises were sighted and 7041 sonar signals were recorded by loggers. The acoustic data loggers recorded ultrasonic signals of porpoises clearly, and detected the presence of porpoises with a correct detection level of 77.6% and a false alarm level of 5.8% within an effective distance of 150 m. Results indicated that the stationed passive acoustic observation method was effective in detecting the presence of porpoises and showed potential in estimating the group size. A positive linear correlation between the number of recorded signals and the group size of sighted porpoises was indicated, although it is faced with some uncertainty and requires further investigation.

  13. Fish otoliths: do sizes correlate with taxonomic group, habitat and/or luminescence?

    PubMed

    Paxton, J R

    2000-09-29

    Otoliths are dense structures in the ears of fishes that function in hearing and gravity perception. Otolith (sagitta) diameters, as percentages of standard length (% SL), are calculated for 247 marine fish species in 147 families and compared by taxonomic group (usually order), habitat and presence or absence of luminescence. Otolith sizes range from 0.4-31.4 mm and 0.08-11.2% SL. The eel and spiny eel orders Anguilliformes and Notacanthiformes have small to very small otoliths, as do the triggerfish order Tetraodontiformes, pipefish order Gasterosteiformes, billfish suborder Scombroidei and many of the dragonfish order Stomiiformes. The soldierfish order Beryciformes has moderate to very large otoliths. The perch order Perciformes has a wide range of otolith sizes but most have small to moderate otoliths 2-5% SL. Only 16 out of the 247 species have the relatively largest otoliths, over 7% SL. Seven out of these 16 species are also luminous from a variety of habitats. Luminous species have slightly to much larger otoliths than non-luminous species in the same family Both beryciforms and luminous fishes live in low-light environments, where acute colour vision is probably impossible. Most fishes of the epipelagic surface waters have very small otoliths, perhaps due to background noise and/or excessive movement of heavy otoliths in rough seas. Bathypelagic species usually have small otoliths and regressed or absent swimbladders. Other habitats have species with a range of otolith sizes. While the relationship between hearing ability and otolith length is unknown, at least some groups with modified swim-bladders have larger otoliths, which may be associated with more acute hearing. PMID:11079419

  14. Fish otoliths: do sizes correlate with taxonomic group, habitat and/or luminescence?

    PubMed Central

    Paxton, J R

    2000-01-01

    Otoliths are dense structures in the ears of fishes that function in hearing and gravity perception. Otolith (sagitta) diameters, as percentages of standard length (% SL), are calculated for 247 marine fish species in 147 families and compared by taxonomic group (usually order), habitat and presence or absence of luminescence. Otolith sizes range from 0.4-31.4 mm and 0.08-11.2% SL. The eel and spiny eel orders Anguilliformes and Notacanthiformes have small to very small otoliths, as do the triggerfish order Tetraodontiformes, pipefish order Gasterosteiformes, billfish suborder Scombroidei and many of the dragonfish order Stomiiformes. The soldierfish order Beryciformes has moderate to very large otoliths. The perch order Perciformes has a wide range of otolith sizes but most have small to moderate otoliths 2-5% SL. Only 16 out of the 247 species have the relatively largest otoliths, over 7% SL. Seven out of these 16 species are also luminous from a variety of habitats. Luminous species have slightly to much larger otoliths than non-luminous species in the same family Both beryciforms and luminous fishes live in low-light environments, where acute colour vision is probably impossible. Most fishes of the epipelagic surface waters have very small otoliths, perhaps due to background noise and/or excessive movement of heavy otoliths in rough seas. Bathypelagic species usually have small otoliths and regressed or absent swimbladders. Other habitats have species with a range of otolith sizes. While the relationship between hearing ability and otolith length is unknown, at least some groups with modified swim-bladders have larger otoliths, which may be associated with more acute hearing. PMID:11079419

  15. Enriched cages for groups of laboratory male rats and their effects on behaviour, weight gain and adrenal glands.

    PubMed

    Lidfors, L; Wichman, A; Ewaldsson, B; Lindh, A-S

    2014-01-01

    We investigated if there were any negative effects on the behaviour and physiology of rats housed in groups of five in two types of enriched cages and compared them with paired-housed rats housed in traditional cages. Eighty-four male Wistar and Sprague-Dawley rats were housed in an enriched rat cage (ERC), a rebuilt rabbit cage (RRC) or a Makrolon III cage (MC) system from 5-16 weeks of age with access to different enrichments. Recordings of behaviour and cage use (3 × 24 h video recording), weekly weighing, measuring food consumption four days/week and water consumption two days/week, were carried out. The rats' muscle strength was assessed using the 'inclined plane' at the end of the study, and after euthanasia the adrenal glands were removed and weighed. Being in the shelter was the most common behaviour in the ERC and RRC groups. In the MC group, which lacked a shelter, rats performed the highest percentage of lying, grooming, rearing, play fighting and manipulating paper shreds. Rats in the RRC had the highest percentage of standing and manipulating gnawing sticks. Water consumption was higher in MC than in ERC and RRC rats. Rats from the RRC managed to remain at a steeper angle on the 'inclined plane' than rats from the MC. There were no significant effects of cage type on weight gain, food consumption or relative weights of adrenal glands. In conclusion, male rats kept in groups of five in larger enriched cages benefited from the enrichments, and no negative effects were found in the larger groups. PMID:24080597

  16. No size or density effect on alternative mate-locating tactics in the tropical damselfly Hetaerina rosea males (Odonata: Calopterygidae).

    PubMed

    Peixoto, Paulo Enrique C; De Marco, Paulo

    2009-01-01

    Males of the damselfly Hetaerina rosea may defend mating sites along river margins (resident males) or, alternatively, wander among different areas presumably searching for mates (nonterritorial males). Although the occurrence of territorial and nonterritorial males of H. rosea is very common in Brazil, studies examining which factors may be responsible for the adoption of alternative mate-locating tactics in this species are inexistent. We investigated the relationship between the adoption of these alternative mate-locating tactics by males of H. rosea and two possible causes: body weight and male abundance. We carried the study in three areas: sites 1, 2 and 3. Samples were monthly undertaken in sites 1 and 2 between September/2001 and August/2002 and in site 3 between May/1999 and January/2001. Using the scan method with fixed areas and mark-resighting techniques, we did not find any relationship between the proportion of nonterritorial males and male abundance per month on sites 2 (n=6) and 3 (n=7), indicating that the adoption of alternative mate-locating tactics is not affected by competition for territories. In the same way, nonterritorial and resident males showed similar body and thoracic weight measures (n=30 and n=27 for sites 2 and 3 respectively). Maybe the nonterritorial tactic is adopted by individuals searching for better territories or males that were evicted from their defended sites. The absence of relationship between weight and male territorial status is in accordance with other Hetaerina species. However, other traits not investigated here such as parasitic load, fat content and age may influence the adoption of different mate-acquisition tactics in H. rosea males. PMID:19637713

  17. The ACTN3 R577X Polymorphism across Three Groups of Elite Male European Athletes

    PubMed Central

    Eynon, Nir; Ruiz, Jonatan R.; Femia, Pedro; Pushkarev, Vladimir P.; Cieszczyk, Pawel; Maciejewska-Karlowska, Agnieszka; Sawczuk, Marek; Dyatlov, Dmitry A.; Lekontsev, Evgeny V.; Kulikov, Leonid M.; Birk, Ruth

    2012-01-01

    The ACTN3 R577X polymorphism (rs1815739) is a strong candidate to influence elite athletic performance. Yet, controversy exists in the literature owing to between-studies differences in the ethnic background and sample size of the cohorts, the latter being usually low, which makes comparisons difficult. In this case:control genetic study we determined the association between elite athletic status and the ACTN3 R577X polymorphism within three cohorts of European Caucasian men, i.e. Spanish, Polish and Russian [633 cases (278 elite endurance and 355 power athletes), and 808 non-athletic controls]. The odds ratio (OR) of a power athlete harbouring the XX versus the RR genotype compared with sedentary controls was 0.54 [95% confidence interval (CI): 0.34–0.48; P = 0.006]. We also observed that the OR of an endurance athlete having the XX versus the RR genotype compared with power athletes was 1.88 (95%CI: 1.07–3.31; P = 0.028). In endurance athletes, the OR of a “world-class” competitor having the XX genotype versus the RR+RX genotype was 3.74 (95%CI: 1.08–12.94; P = 0.038) compared with those of a lower (“national”) competition level. No association (P>0.1) was noted between the ACTN3 R577X polymorphism and competition level (world-class versus national-level) in power athletes. Our data provide comprehensive support for the influence of the ACTN3 R577X polymorphism on elite athletic performance. PMID:22916217

  18. Analysis of Occupational Accident Fatalities and Injuries Among Male Group in Iran Between 2008 and 2012

    PubMed Central

    Alizadeh, Seyed Shamseddin; Mortazavi, Seyed Bagher; Sepehri, Mohammad Mehdi

    2015-01-01

    Background: Because of occupational accidents, permanent disabilities and deaths occur and economic and workday losses emerge. Objectives: The purpose of the present study was to investigate the factors responsible for occupational accidents occurred in Iran. Patients and Methods: The current study analyzed 1464 occupational accidents recorded by the Ministry of Labor and Social Affairs’ offices in Iran during 2008 - 2012. At first, general understanding of accidents was obtained using descriptive statistics. Afterwards, the chi-square test and Cramer’s V statistic (Vc) were used to determine the association between factors influencing the type of injury as occupational accident outcomes. Results: There was no significant association between marital status and time of day with the type of injury. However, activity sector, cause of accident, victim’s education, age of victim and victim’s experience were significantly associated with the type of injury. Conclusions: Successful accident prevention relies largely on knowledge about the causes of accidents. In any accident control activity, particularly in occupational accidents, correctly identifying high-risk groups and factors influencing accidents is the key to successful interventions. Results of this study can cause to increase accident awareness and enable workplace’s management to select and prioritize problem areas and safety system weakness in workplaces. PMID:26568848

  19. THE ESTROGENIC AND ANTIANDROGENIC PESTICIDE METHOXYCHLOR ALTERS THE REPRODUCTIVE TRACT AND BEHAVIOR WITHOUT AFFECTING PITUITARY SIZE OR LH AND PROLACTIN SECRETION IN MALE RATS

    EPA Science Inventory

    The estrogenic and antiandrogenic pesticide methoxychlor alters the reproductive tract and behavior without affecting pituitary size or LH and prolactin secretion in male rats.

    Gray LE Jr, Ostby J, Cooper RL, Kelce WR.

    Endocrinology Branch, United States Environment...

  20. Hyphal responses of Neurospora crassa to micron-sized beads with functional chemical surface groups

    NASA Astrophysics Data System (ADS)

    Held, Marie; Edwards, Clive; Nicolau, Dan V.

    2011-02-01

    Filamentous fungi include serious plant and animal pathogens that explore their environment efficiently in order to penetrate the host. This environment is physically and chemically heterogeneous and the fungi rely on specific physical and chemical signals to find the optimal point/s of attack. This study presents a methodology to introduce distinct structures with dimensions similar to the hyphal diameter and specific chemical surface groups into a controllable environment in order to study the fungal response. We introduced 3.3 μm polystyrene beads covered with Epoxy surface groups into microfluidic channels made from PDMS by rapid replica molding. The experimental setup resulted in different areas with low and high densities of beads as well as densely packed patches. The observations of the fungus exploring the areas long-term showed that the growth parameters were altered significantly, compared with the values measured on agar. The fungus responded to both, the physical and chemical parameters of the beads, including temporary directional changes, increased branching angles, decreased branching distances, decreased apical extension velocities and occasional cell wall lysis. The wealth and magnitude of the observed responses indicates that the microfluidic structures provide a powerful platform for the investigation of micron-sized features on filamentous fungi.

  1. A simple ratio-based approach for power and sample size determination for 2-group comparison using Rasch models

    PubMed Central

    2014-01-01

    Background Despite the widespread use of patient-reported Outcomes (PRO) in clinical studies, their design remains a challenge. Justification of study size is hardly provided, especially when a Rasch model is planned for analysing the data in a 2-group comparison study. The classical sample size formula (CLASSIC) for comparing normally distributed endpoints between two groups has shown to be inadequate in this setting (underestimated study sizes). A correction factor (RATIO) has been proposed to reach an adequate sample size from the CLASSIC when a Rasch model is intended to be used for analysis. The objective was to explore the impact of the parameters used for study design on the RATIO and to identify the most relevant to provide a simple method for sample size determination for Rasch modelling. Methods A large combination of parameters used for study design was simulated using a Monte Carlo method: variance of the latent trait, group effect, sample size per group, number of items and items difficulty parameters. A linear regression model explaining the RATIO and including all the former parameters as covariates was fitted. Results The most relevant parameters explaining the ratio’s variations were the number of items and the variance of the latent trait (R2 = 99.4%). Conclusions Using the classical sample size formula adjusted with the proposed RATIO can provide a straightforward and reliable formula for sample size computation for 2-group comparison of PRO data using Rasch models. PMID:24996957

  2. The Size and Nature of Lyman- alpha Forest Clouds Probed by QSO Pairs and Groups

    NASA Astrophysics Data System (ADS)

    Fang, Yihu; Duncan, Robert C.; Crotts, Arlin P. S.; Bechtold, Jill

    1996-05-01

    Closely separated QSO pairs and groups make it possible to probe the size, geometry, and spatial clustering of Lyα forest clouds. Recent spectroscopic observations of Q1343 + 2640A/B give evidence that the transverse sizes of Lyα clouds are very large at redshifts ~2 (as reported by Bechtold et al. in 1994). In this paper, we describe a robust Bayesian statistical method for determining cloud sizes in spherical and in thin disk geometries, apply this method to the available data, and discuss implications of our results for models of Lyα clouds. Under the assumption of a population of uniform-sized and unclustered Lyα clouds, the data from Q1343 + 2640A/B give a 99% confidence lower and upper bounds 61 < R < 533 h^-1^ kpc on the radius of spherical clouds at z ~ 1.8, with a median value of 149 h^-1^ kpc [({OMEGA}_0_, {LAMBDA}_0_) = (1,0), and h = H_0_/100 km s^-1^ Mpc^-1^]. The baryonic mass of such large clouds, if they are roughly homogeneous and quasi-spherical, is comparable to the baryonic mass of dwarf irregular galaxies. Their cosmic overdensity is close to the turnaround density but generally below the virialization density, which suggests a population of gravitationally bound but unvirialized protogalactic objects at z ~ 2. The comoving volume density of these clouds is similar to that of the faint blue galaxies (FBGs) at the limiting magnitude B~26-27, if these FBGs are distributed approximately over the range of redshift from 0.8 to 2. The timescale for dynamical collapse of overdensities like these clouds is also comparable to the cosmic time difference between z ~ 2 and z ~ 1. Both populations of objects show similar weak clustering in space. All this evidence suggests a possible identification of Lyα clouds as the collapsing progenitors of the FBGs at z~1. We also investigate the other closely separated QSO pairs with published high-quality spectra: Q0307- 1931/0307-1932, Q0107-0232/0107- 0235, and the triplet of Q1623 +268. Imposing a uniform W_0

  3. Comparison of cardiovascular risk profile between male employees of two automotives companies in France and Sweden. The Coeur Project Group.

    PubMed

    Simon, A; Dimberg, L; Levenson, J; Lanoiselée, C; Massonneau, M; Eriksson, B; Jern, S; Kumlin, L; Marin, P; Dahlöf, B; Hansson, L; Björntorp, P

    1997-12-01

    To determine whether or not the lower rate of coronary disease in France, in comparison with Sweden, might be explained by different cardiovascular risk profiles, a cross-sectional analysis (first step of a longitudinal study) of comparable samples of automotive workers was carried out in corporate occupational health clinics of Renault and Volvo. Traditional cardiovascular risk factors were evaluated and the Framingham coronary risk was estimated for 1000 randomly selected 45-50 years old Caucasian males from each company. Compared with the Frenchmen, the Swedish men consisted of more white collar workers and were slightly older. After adjustment for age and blue/white collar status, the Swedish men showed lower body mass indexes, waist to hip rations and heart rates, lower frequency of treatment of hypercholesterolemia and diabetes than the Frenchmen. The Swedish males also exhibited higher averages of blood cholesterol, low density lipoprotein (LDL) cholesterol and glucose, but lower frequencies of hypercholestrolemia and diabetes, and a higher frequency of family histories of cardiovascular disease. Blood pressure, hypertension prevalence, triglycerides level, and high density lipoprotein (HDL) did not differ between the groups. The average number of traditional risk factors was 1.1/person for the Frenchmen and 0.8/person for the Swedes. However, the coronary risk as estimated using the Framingham index was not different between the groups. This, together with the more frequent family history of cardiovascular disease in Swedish men, suggests a lower susceptibility to risk factors as a possible explanation for the lower cardiovascular disease prevalence reported in France, and/or the possibility that factors not measured were involved. PMID:9476817

  4. Effects of Group Size and Lack of Sphericity on the Recovery of Clusters in K-Means Cluster Analysis

    ERIC Educational Resources Information Center

    de Craen, Saskia; Commandeur, Jacques J. F.; Frank, Laurence E.; Heiser, Willem J.

    2006-01-01

    K-means cluster analysis is known for its tendency to produce spherical and equally sized clusters. To assess the magnitude of these effects, a simulation study was conducted, in which populations were created with varying departures from sphericity and group sizes. An analysis of the recovery of clusters in the samples taken from these…

  5. Sexually selected lip colour indicates male group-holding status in the mating season in a multi-level primate society

    PubMed Central

    Grueter, Cyril C.; Zhu, Pingfen; Allen, William L.; Higham, James P.; Ren, Baoping; Li, Ming

    2015-01-01

    Sexual selection typically produces ornaments in response to mate choice, and armaments in response to male–male competition. Unusually among mammals, many primates exhibit colour signals that may be related to one or both processes. Here, we document for the first time correlates of facial coloration in one of the more brightly coloured primates, the black-and-white snub-nosed monkey (Rhinopithecus bieti). Snub-nosed monkeys have a one-male unit (OMU) based social organization, but these units aggregate semi-permanently into larger bands. This form of mating system causes many males to become associated with bachelor groups. We quantified redness of the prominent lower lip in 15 males (eight bachelors, seven OMU holders) in a group at Xiangguqing, China. Using mixed models, our results show that lip redness increases with age. More interestingly, there is a significant effect of the interaction of group-holding status and mating season on redness; that is, lip colour of OMU males undergoes reddening in the mating season, whereas the lips of subadult and juvenile bachelor males become paler at that time of year. These results indicate that lip coloration is a badge of (group-holding) status during the mating season, with non-adults undergoing facial differentiation, perhaps to avoid the costs of reproductive competition. Future research should investigate whether lip coloration is a product of male–male competition, and/or female mate choice. PMID:27019735

  6. Renormalization-group theory for finite-size scaling in extreme statistics.

    PubMed

    Györgyi, G; Moloney, N R; Ozogány, K; Rácz, Z; Droz, M

    2010-04-01

    We present a renormalization-group (RG) approach to explain universal features of extreme statistics applied here to independent identically distributed variables. The outlines of the theory have been described in a previous paper, the main result being that finite-size shape corrections to the limit distribution can be obtained from a linearization of the RG transformation near a fixed point, leading to the computation of stable perturbations as eigenfunctions. Here we show details of the RG theory which exhibit remarkable similarities to the RG known in statistical physics. Besides the fixed points explaining universality, and the least stable eigendirections accounting for convergence rates and shape corrections, the similarities include marginally stable perturbations which turn out to be generic for the Fisher-Tippett-Gumbel class. Distribution functions containing unstable perturbations are also considered. We find that, after a transitory divergence, they return to the universal fixed line at the same or at a different point depending on the type of perturbation. PMID:20481705

  7. Male dominance linked to size and age, but not to 'good genes' in brown trout (Salmo trutta)

    PubMed Central

    Jacob, Alain; Nusslé, Sébastien; Britschgi, Adrian; Evanno, Guillaume; Müller, Rudolf; Wedekind, Claus

    2007-01-01

    Background Males that are successful in intra-sexual competition are often assumed to be of superior quality. In the mating system of most salmonid species, intensive dominance fights are common and the winners monopolise most mates and sire most offspring. We drew a random sample of mature male brown trout (Salmo trutta) from two wild populations and determined their dominance hierarchy or traits linked to dominance. The fish were then stripped and their sperm was used for in vitro fertilisations in two full-factorial breeding designs. We recorded embryo viability until hatching in both experiments, and juvenile survival during 20 months after release into a natural streamlet in the second experiment. Since offspring of brown trout get only genes from their fathers, we used offspring survival as a quality measure to test (i) whether males differ in their genetic quality, and if so, (ii) whether dominance or traits linked to dominance reveal 'good genes'. Results We found significant additive genetic variance on embryo survival, i.e. males differed in their genetic quality. Older, heavier and larger males were more successful in intra-sexual selection. However, neither dominance nor dominance indicators like body length, weight or age were significantly linked to genetic quality measured as embryo or juvenile survival. Conclusion We found no evidence that females can improve their offspring's genetic viability by mating with large and dominant males. If there still were advantages of mating with dominant males, they may be linked to non-genetic benefits or to genetic advantages that are context dependent and therefore possibly not revealed under our experimental conditions – even if we found significant additive genetic variation for embryo viability under such conditions. PMID:17974038

  8. One size does not fit all: HIV testing preferences differ among high-risk groups in Northern Tanzania

    PubMed Central

    Ostermann, Jan; Njau, Bernard; Mtuy, Tara; Brown, Derek S.; Mühlbacher, Axel; Thielman, Nathan

    2014-01-01

    In order to maximize the effectiveness of “Seek, Test, and Treat” strategies for curbing the HIV epidemic, new approaches are needed to increase the uptake of HIV testing services, particularly among high-risk groups. Low HIV testing rates among such groups suggests that current testing services may not align well with the testing preferences of these populations. Female bar workers and male mountain porters have been identified as two important high-risk groups in the Kilimanjaro Region of Tanzania. We used conventional survey methods and a Discrete Choice Experiment (DCE), a preference elicitation method increasingly applied by economists and policy makers to inform health policy and services, to analyze trade-offs made by individuals and quantify preferences for HIV testing services. Compared to 486 randomly selected community members, 162 female bar workers and 194 male Kilimanjaro porters reported 2 to 3 times as many lifetime sexual partners (p<0.001), but similar numbers of lifetime HIV tests (median 1–2 across all groups). Bivariate descriptive statistics were used to analyze differences in survey responses across groups. For the DCE, participants’ stated choices across 11,178 hypothetical HIV testing scenarios (322 female and 299 male participants × 9 choice tasks × 2 alternatives) were analyzed using gender-specific mixed logit models. Direct assessments and the DCE data demonstrated that barworkers were less likely to prefer home testing and were more concerned about disclosure issues compared with their community counterparts. Male porters preferred testing in venues where antiretroviral therapy was readily available. Both high-risk groups were less averse to traveling longer distances to test compared to their community counterparts. These results expose systematic differences in HIV testing preferences across high-risk populations compared to their community peers. Tailoring testing options to the preferences of high-risk populations should

  9. Human Activity Dampens the Benefits of Group Size on Vigilance in Khulan (Equus hemionus) in Western China.

    PubMed

    Wang, Mu-Yang; Ruckstuhl, Kathreen E; Xu, Wen-Xuan; Blank, David; Yang, Wei-Kang

    2016-01-01

    Animals receive anti-predator benefits from social behavior. As part of a group, individuals spend less time being vigilant, and vigilance decreases with increasing group size. This phenomenon, called "the many-eyes effect", together with the "encounter dilution effect", is considered among the most important factors determining individual vigilance behavior. However, in addition to group size, other social and environmental factors also influence the degree of vigilance, including disturbance from human activities. In our study, we examined vigilance behavior of Khulans (Equus hemionus) in the Xinjiang Province in western China to test whether and how human disturbance and group size affect vigilance. According to our results, Khulan showed a negative correlation between group size and the percentage time spent vigilant, although this negative correlation depended on the groups' disturbance level. Khulan in the more disturbed area had a dampened benefit from increases in group size, compared to those in the undisturbed core areas. Provision of continuous areas of high-quality habitat for Khulans will allow them to form larger undisturbed aggregations and to gain foraging benefits through reduced individual vigilance, as well as anti-predator benefits through increased probability of predator detection. PMID:26756993

  10. Developing the Noncentrality Parameter for Calculating Group Sample Sizes in Heterogeneous Analysis of Variance

    ERIC Educational Resources Information Center

    Luh, Wei-Ming; Guo, Jiin-Huarng

    2011-01-01

    Sample size determination is an important issue in planning research. In the context of one-way fixed-effect analysis of variance, the conventional sample size formula cannot be applied for the heterogeneous variance cases. This study discusses the sample size requirement for the Welch test in the one-way fixed-effect analysis of variance with…

  11. Brain Size, IQ, and Racial-Group Differences: Evidence from Musculoskeletal Traits.

    ERIC Educational Resources Information Center

    Rushton, J. Philippe; Rushton, Elizabeth W.

    2003-01-01

    Correlated brain size differences with 37 musculoskeletal variables shown in evolutionary textbooks to change with brain size. Findings from a sample of more than 6,000 U.S. military personnel indicate that racial differences in brain size are securely established and are the most likely biological mediators of race differences in intelligence.…

  12. Selection for a dominant oncogene and large male size as a risk factor for melanoma in the Xiphophorus animal model

    PubMed Central

    Fernandez, André A.; Bowser, Paul R.

    2010-01-01

    Summary Adult height is a risk factor in numerous human cancers that involve aberrant receptor tyrosine kinase (RTK) signaling. However, its importance is debated due to conflicting epidemiological studies and the lack of useful in vivo models. In Xiphophorus fishes (Platyfishes/Swordtails), a functional RTK, Xiphophorus melanoma receptor kinase (Xmrk), serves as the dominant oncogene and has been maintained for several million years despite being deleterious and in an extremely unstable genomic region. Here we show that the Xmrk genotype is positively correlated with standard length in male and female wild caught Xiphophorus cortezi sampled throughout their phylogeographic distribution. Histopathology confirms the occurrence of malignant melanomas in both sexes; however, melanoma incidence was extremely male biased. Furthermore, males collected with malignant melanomas in the field were significantly larger than both Xmrk males collected without melanomas and wildtype (Xmrk deficient) males. These results not only provide a novel selective mechanism for the persistence of the germline Xmrk oncogene but also create an innovative avenue of melanoma research within the Xiphophorus fishes. Wildlife cancer in natural systems is a growing concern, therefore, future research investigating life history characteristics associated with certain phenotypes and genotypes that predispose an individual to cancer will be fundamental to increasing our understanding of the evolutionary biology of cancer in nature as well as in humans. PMID:20618898

  13. Human Activity Dampens the Benefits of Group Size on Vigilance in Khulan (Equus hemionus) in Western China

    PubMed Central

    Wang, Mu-Yang; Ruckstuhl, Kathreen E.; Xu, Wen-Xuan; Blank, David; Yang, Wei-Kang

    2016-01-01

    Animals receive anti-predator benefits from social behavior. As part of a group, individuals spend less time being vigilant, and vigilance decreases with increasing group size. This phenomenon, called “the many-eyes effect”, together with the “encounter dilution effect”, is considered among the most important factors determining individual vigilance behavior. However, in addition to group size, other social and environmental factors also influence the degree of vigilance, including disturbance from human activities. In our study, we examined vigilance behavior of Khulans (Equus hemionus) in the Xinjiang Province in western China to test whether and how human disturbance and group size affect vigilance. According to our results, Khulan showed a negative correlation between group size and the percentage time spent vigilant, although this negative correlation depended on the groups’ disturbance level. Khulan in the more disturbed area had a dampened benefit from increases in group size, compared to those in the undisturbed core areas. Provision of continuous areas of high-quality habitat for Khulans will allow them to form larger undisturbed aggregations and to gain foraging benefits through reduced individual vigilance, as well as anti-predator benefits through increased probability of predator detection. PMID:26756993

  14. Relationship between beak morphological variables and body size and mantle length of male and female Argentine shortfin squid ( Illex argentinus)

    NASA Astrophysics Data System (ADS)

    Chen, Xinjun; Lu, Huajie; Liu, Bilin; Fang, Zhou

    2012-12-01

    Beak of cephalopod is an important hard tissue. Understanding the morphology of beak can yield critical information on the role of cephalopods in the ecosystem. The south patagonic stock of the Argentine shortfin squid, Illex argentinus, is not only one of the most important fishing targets, but also one of the most important species in the marine eco-system of the southwest Atlantic. A total of 430 samples of I. argentinus, including 229 females 103-346mm in mantle length (ML) and 201 males 140-298mm in ML, were collected from the area off the Exclusive Economic Zone of Argentinean waters by Chinese squid jigging vessels during February to May 2007. The morphology of their beaks was evaluated. The relationships between beak morphological variables and ML differed significantly among males and females. They could be best described by logarithmic functions for females and linear functions for males except for upper wing length (UWL) and lower rostrum length (LRL), which followed exponential functions in their relationships with ML. The results showed the sexual dimorphism in the relationship between ML and beak morphology for the south patagonic stock of I. argentinus. However, no significant difference was found between males and females in the relationships of beak morphological variables (except for UWL) versus body weight (BW), suggesting that the relationship between beak morphological variables and BW can be used for estimating the biomass consumed by their predators.

  15. How Big Is Your Y? A Genome Sequence-Based Estimate of the Size of the Male-Specific Region in Megaselia scalaris

    PubMed Central

    Hoehn, Kenneth B.; Noor, Mohamed A. F.

    2014-01-01

    The scuttle fly, Megaselia scalaris, is often cited as a model in which to study early sex chromosome evolution because of its homomorphic sex chromosomes, low but measurable molecular differentiation between sex chromosomes, and occasional transposition of the male-determining element to different chromosomes in laboratory cultures. Counterintuitively, natural isolates consistently show sex linkage to the second chromosome. Frequent natural transposition of the male-determining element should lead to the loss of male specificity of any nontransposed material on the previous sex-linked chromosome pair. Using next-generation sequencing data from a newly obtained natural isolate of M. scalaris, we show that even highly conservative estimates for the size of the male-specific genome are likely too large to be contained within a transposable element. This result strongly suggests that transposition of the male-determining region either is extremely rare or has not persisted recently in natural populations, allowing for differentiation of the sex chromosomes of this species. PMID:25380730

  16. GI Joe or Average Joe? The impact of average-size and muscular male fashion models on men's and women's body image and advertisement effectiveness.

    PubMed

    Diedrichs, Phillippa C; Lee, Christina

    2010-06-01

    Increasing body size and shape diversity in media imagery may promote positive body image. While research has largely focused on female models and women's body image, men may also be affected by unrealistic images. We examined the impact of average-size and muscular male fashion models on men's and women's body image and perceived advertisement effectiveness. A sample of 330 men and 289 women viewed one of four advertisement conditions: no models, muscular, average-slim or average-large models. Men and women rated average-size models as equally effective in advertisements as muscular models. For men, exposure to average-size models was associated with more positive body image in comparison to viewing no models, but no difference was found in comparison to muscular models. Similar results were found for women. Internalisation of beauty ideals did not moderate these effects. These findings suggest that average-size male models can promote positive body image and appeal to consumers. PMID:20488770

  17. A Note on Testing for Homogeneity Among Effect Sizes Sharing a Common Control Group

    ERIC Educational Resources Information Center

    Cook, Samantha R.

    2004-01-01

    L. V. Hedges and I. Olkin (1985) presented a statistic to test for homogeneity among correlated effect sizes and L. J. Gleser and I. Olkin (1994) presented a large-sample approximation to the covariance matrix of the correlated effect sizes. This article presents a more exact expression for this covariance matrix, assuming normally distributed…

  18. Effect of relative weight group change on NMR spectroscopy derived lipid particle size and concentrations among adolescents

    PubMed Central

    Jago, Russell; Drews, Kimberley L.; Otvos, James D.; Foster, Gary D.; Marcus, Marsh D.; Buse, John B.; Mietus-Snyder, Michele; Willi, Steven M.

    2014-01-01

    Objective To examine whether longitudinal changes in relative weight category (as indicated by change in BMI classification group) were associated with changes in nuclear magnetic resonance (NMR) derived lipoprotein particles among US youth. Study design Secondary analysis of data from clustered RCT. BMI and fasting blood samples were obtained from 2069 participants at the start of 6th grade and end of 8th grade. BMI was categorized as normal weight, overweight or obese at both time points. Lipoprotein particle profiles were measured using NMR spectroscopy at both time points. Regression models were used to examine changes in relative weight group and change in lipoprotein variables. Results 38% of participants changed relative weight category (BMI group) over the 2.5 year study period. Low density lipoprotein cholesterol and non-high density lipoprotein cholesterol decreased almost universally, but more with improved BMI category. There were adverse effects on LDL size and total LDL particles, high density lipoprotein size and cholesterol for participants who remained obese or whose relative weight group worsened. Changes in relative category had no impact on HDL particles. Conclusion Improvement in relative weight group from 6th to 8th grade was associated with favorable changes in non-HDL-C, VLDL size, LDL size, HDL size and LDL particles, but had no effect on HDL particles. Findings indicate that an improvement in relative weight group between 6th and 8th grade had an effect on NMR derived particles sizes and concentrations among a large group of adolescents, which overrepresented low-income minorities. PMID:24508445

  19. The Role of Context-Specific Norms and Group Size in Alcohol Consumption and Compliance Drinking During Natural Drinking Events

    PubMed Central

    Cullum, Jerry; O’Grady, Megan; Armeli, Stephen; Tennen, Howard

    2016-01-01

    Using experience sampling methods we examined how group size and context-specific drinking norms corresponded to alcohol consumption and compliance with drinking offers during natural social drinking events. For 30 days, 397 college students reported daily on their alcohol consumption during social events, the size of the group they were with, the average alcohol consumption of its’ members, and the number of drinks they accepted that came directly from the group they were with during these social drinking events. Larger groups corresponded with greater alcohol consumption, but only when context-specific norms were high. Furthermore, larger groups increased compliance with drinking offers when context-specific norms were high, but decreased compliance with drinking offers when context-specific norms were low. Thus, subtle features of the social-context may influence not only overall consumption behavior, but also compliance with more overt forms of social influence.

  20. The Effect of Group Size on Individual Achievement in Beginning Piano Classes.

    ERIC Educational Resources Information Center

    Jackson, Anita

    1980-01-01

    A total of 44 preschool, elementary, high school, and college students were taught piano in groups of two, four, six, and eight. The evaluation consisted of 15 basic keyboard skills. Results from tests for combined groups and for age level groups revealed no statistically significant differences in individual achievement. (Author/SJL)

  1. Factors influencing behavior of group-housed male rats in the social interaction test: focus on cohort removal.

    PubMed

    Kask, A; Nguyen, H P; Pabst, R; von Hörsten, S

    2001-10-01

    The rat social interaction (SI) test is used widely to measure anxiety-like behavior, yet the influence of various factors such as testing time, pre-experimental manipulations (transport stress), and testing of animals from the same cage (cohort removal, CR) on SI has not been systematically studied. We measured SI behavior of male triad-housed Wistar rats in a novel dimly lit arena (low light unfamiliar, LU) and found that SI time is higher in the beginning of the activity (dark) phase when compared with SI time in first half of the light phase. Furthermore, SI time is significantly increased by habituation of animals to the testing room during light phase, but this intervention has no effect in early dark phase when SI behavior is already maximal. Sequential removal of rats from the home cage led to the stress-like behavioral and physiological consequences. Rats removed in the last position had shorter SI time and higher body temperature. These data demonstrate that SI is higher during early dark vs. early light phase and confirm that CR has anxiogenic-like effects in rats. We conclude that the usage of sequentially removed group-housed rats in behavioral tests can be a source for considerable variation due to anxiety that develops in animals remaining in the cage. On the other hand, CR may be a useful method to study behavioral/neurochemical mechanisms of psychogenic stress in rats. PMID:11714489

  2. Social support and negative and positive outcomes of experienced traumatic events in a group of male emergency service workers

    PubMed Central

    Ogińska-Bulik, Nina

    2015-01-01

    The paper investigates the relationship between perceived social support in the workplace and both negative (post-traumatic stress disorder (PTSD) symptoms) and positive outcomes (post-traumatic growth) of experienced traumatic events in a group of male emergency service workers. Data of 116 workers representing emergency services (37.1% firefighters, 37.1%, police officers and 30% medical rescue workers) who have experienced a traumatic event in their worksite were analyzed. The range of age of the participants was 21–57 years (M = 35.27; SD = 8.13). Polish versions of the Impact of Event Scale – Revised and the Post-traumatic Growth Inventory were used to assess the negative and positive outcomes of the experienced event. A perceived social support scale was measured by the scale What support you can count on. The data obtained from the study revealed the negative dependence of social support from supervisors with PTSD symptoms and positive – social support from co-workers with post-traumatic growth. Moreover the results of the study indicate the positive relationship between negative and positive outcomes of experienced traumatic events in the workplace. Perceived social support plays a more important role in gaining benefits from trauma than preventing negative outcomes of the experienced traumatic event. Support from co-workers, compared to support from supervisors, has greater importance. PMID:26323770

  3. Effect of Parasitoid: Host Ratio and Group Size on Fitness of Spathius galinae (Hymenoptera: Braconidae): Implications for Mass-Rearing.

    PubMed

    Watt, Timothy J; Duan, Jian J; Tallamy, Douglas W; Hough-Goldstein, Judith

    2015-06-01

    Producing insect natural enemies in laboratories or insectaries for biological pest control is often expensive, and developing cost-effective rearing techniques is a goal of many biological control programs. Spathius galinae Belokobylskij and Strazenac (Hymenoptera: Braconidae), a newly described ectoparasitoid of emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is currently being evaluated for environmental introduction in the United States to provide biological control of this invasive pest. To improve mass-rearing outcomes for S. galinae, we investigated the effects of parasitoid: host ratio and parasitoid and host group size (density) on parasitoid fitness. Our results showed that when 1 emerald ash borer larva was exposed to 1, 2, 4, or 8 female parasitoids, parasitism rate was positively associated with increasing parasitoid: host ratio, while brood size, sex ratio, and fitness estimates of progeny were not affected. When a constant 1:1 parasitoid: host ratio was used, but group size varied from 1 female parasitoid and 1 host, 5 parasitoids and 5 hosts, 10 of each, and 20 of each in same size rearing cages, parasitism rates were highest when at least 5 females were exposed to 5 host larvae. Moreover, the number of progeny produced per female parasitoid was greatest when group size was 10 parasitoids and 10 hosts. These findings demonstrate that S. galinae may be reared most efficiently in moderately high-density groups (10 parasitoids and hosts) and with a 1:1 parasitoid: host ratio. PMID:26470215

  4. Size-selective feeding on phytoplankton by two morpho-groups of the small freshwater fish Amblypharyngodon mola.

    PubMed

    Nandi, S; Saikia, S K

    2015-08-01

    Two morpho-groups (i.e., small, MGS and big, MGL) of the small freshwater fish Amblypharyngodon mola were studied for their feeding behaviour in the natural environment. Both the morpho-groups fed on a variety of phytoplankton including Cyanophyceae, Chlorophyceae, Bacillariophyceae and Euglenophyceae. The fish had more Chlorophyceae and Bacillariophyceae in their gut than other phytoplankton. Costello's selectivity plots revealed that the MGS fed on the smaller phytoplankters (2-6 µm in size), whereas the MGL fed on both the small and large (up to 12 µm in size) phytoplankters. The differences in mouth areas between the two morpho-groups were explained as a possible reason of size-selective feeding and contribute to overcome gape limitation in A. mola. This is further accompanied by the uniform pore size of the gills (2 µm) in all the morpho-groups. This study concluded that A. mola exhibits a size-dependent feeding strategy regulated by gape limitation at the ingestion level. With ontogenetic shifts, flexibility appears to overcome such a limitation in the MGL, having a wider mouth area supported by jaw opening ability. PMID:26084383

  5. Population sizes and group characteristics of Siberian Crane (Leucogeranus leucogeranus) and Hooded Crane (Grus monacha) in Poyang Lake Wetland

    PubMed Central

    SHAO, Ming-Qin; GUO, Hong; JIANG, Jian-Hong

    2014-01-01

    Both the Siberian Crane (Leucogeranus leucogeranus) and Hooded Crane (Grus monacha) have limited population sizes and are considered endangered by domestic Chinese and international agencies. To document the current size of their respective populations and characterize their groups, between October 2012 and April 2013 we undertook fieldwork at four nature reserve areas within the Poyang Lake wetlands. We divided Poyanghu National Nature Reserve (PYH) into the Wucheng (PWC) and Hengfeng areas (PHF), because each are each located in different counties. Our fieldwork showed that the Siberian Crane occurred mainly in PYH (364 in the PHF, 158 in the PWC) and the Nanjishan Wetland National Nature Reserve (NJS, with 200 individuals). The Hooded Crane was mainly distributed in PYH (302 in the PHF and 154 in the PWC). Family groups accounted for more than 50% of the total number of groups among both species, with Hooded Cranes forming more family groups than Siberian Cranes. Typically, these groups were formed of two adults with one offspring (Siberian Crane), and two adults with two offspring (Hooded Crane), with the mean family group size of the Siberian Crane and Hooded Crane being respectively 2.65±0.53 (n=43) and 3.09±0.86 (n=47) individuals per group. The mean collective group size of the Siberian Crane and Hooded Crane included 28.09±24.94 (n=23) and 28.94±27.97 (n=16) individuals per group, respectively, with the proportion of juveniles among Hooded Cranes being more than double that seen among the Siberian Cranes. PMID:25297076

  6. How group size affects vigilance dynamics and time allocation patterns: the key role of imitation and tempo.

    PubMed

    Michelena, Pablo; Deneubourg, Jean-Louis

    2011-01-01

    In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation ('group size effect'). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior. With sheep as a model species, we identified how the behaviors of conspecifics affect the individual decisions to switch activity. We highlight a simple mechanism whereby the group size effect on collective vigilance dynamics is shaped by two key features: the magnitude of social amplification and intrinsic differences between foraging and scanning bout durations. Our results highlight a positive correlation between the duration of scanning and foraging bouts at the level of the group. This finding reveals the existence of groups with high and low rates of transition between activities, suggesting individual variations in the transition rate, or 'tempo'. We present a mathematical model based on behavioral rules derived from experiments. Our theoretical predictions show that the system is robust in respect to variations in the propensity to imitate scanning and foraging, yet flexible in respect to differences in the duration of activity bouts. The model shows how individual decisions contribute to collective behavior patterns and how the group, in turn, facilitates individual-level adaptive responses. PMID:21525987

  7. How Group Size Affects Vigilance Dynamics and Time Allocation Patterns: The Key Role of Imitation and Tempo

    PubMed Central

    Michelena, Pablo; Deneubourg, Jean-Louis

    2011-01-01

    In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation (‘group size effect’). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior. With sheep as a model species, we identified how the behaviors of conspecifics affect the individual decisions to switch activity. We highlight a simple mechanism whereby the group size effect on collective vigilance dynamics is shaped by two key features: the magnitude of social amplification and intrinsic differences between foraging and scanning bout durations. Our results highlight a positive correlation between the duration of scanning and foraging bouts at the level of the group. This finding reveals the existence of groups with high and low rates of transition between activies, suggesting individual variations in the transition rate, or ‘tempo’. We present a mathematical model based on behavioral rules derived from experiments. Our theoretical predictions show that the system is robust in respect to variations in the propensity to imitate scanning and foraging, yet flexible in respect to differences in the duration of activity bouts. The model shows how individual decisions contribute to collective behavior patterns and how the group, in turn, facilitates individual-level adaptive responses. PMID:21525987

  8. Influence of prey dispersion on territory and group size of African lions: a test of the resource dispersion hypothesis.

    PubMed

    Valeix, Marion; Loveridge, Andrew J; MacDonald, David W

    2012-11-01

    Empirical tests of the resource dispersion hypothesis (RDH), a theory to explain group living based on resource heterogeneity, have been complicated by the fact that resource patch dispersion and richness have proved difficult to define and measure in natural systems. Here, we studied the ecology of African lions Panthera leo in Hwange National Park, Zimbabwe, where waterholes are prey hotspots, and where dispersion of water sources and abundance of prey at these water sources are quantifiable. We combined a 10-year data set from GPS-collared lions for which information of group composition was available concurrently with data for herbivore abundance at waterholes. The distance between two neighboring waterholes was a strong determinant of lion home range size, which provides strong support for the RDH prediction that territory size increases as resource patches are more dispersed in the landscape. The mean number of herbivore herds using a waterhole, a good proxy of patch richness, determined the maximum lion group biomass an area can support. This finding suggests that patch richness sets a maximum ceiling on lion group size. This study demonstrates that landscape ecology is a major driver of ranging behavior and suggests that aspects of resource dispersion limit group sizes. PMID:23236920

  9. Cost and Impact of Voluntary Medical Male Circumcision in South Africa: Focusing the Program on Specific Age Groups and Provinces

    PubMed Central

    Kripke, Katharine; Thambinayagam, Ananthy; Pillay, Yogan; Loykissoonlal, Dayanund; Bonnecwe, Collen; Barron, Peter; Kiwango, Eva; Castor, Delivette

    2016-01-01

    Background In 2012, South Africa set a goal of circumcising 4.3 million men ages 15–49 by 2016. By the end of March 2014, 1.9 million men had received voluntary medical male circumcision (VMMC). In an effort to accelerate progress, South Africa undertook a modeling exercise to determine whether circumcising specific client age groups or geographic locations would be particularly impactful or cost-effective. Results will inform South Africa’s efforts to develop a national strategy and operational plan for VMMC. Methods and Findings The study team populated the Decision Makers’ Program Planning Tool, Version 2.0 (DMPPT 2.0) with HIV incidence projections from the Spectrum/AIDS Impact Module (AIM), as well as national and provincial population and HIV prevalence estimates. We derived baseline circumcision rates from the 2012 South African National HIV Prevalence, Incidence and Behaviour Survey. The model showed that circumcising men ages 20–34 offers the most immediate impact on HIV incidence and requires the fewest circumcisions per HIV infection averted. The greatest impact over a 15-year period is achieved by circumcising men ages 15–24. When the model assumes a unit cost increase with client age, men ages 15–29 emerge as the most cost-effective group. When we assume a constant cost for all ages, the most cost-effective age range is 15–34 years. Geographically, the program is cost saving in all provinces; differences in the VMMC program’s cost-effectiveness across provinces were obscured by uncertainty in HIV incidence projections. Conclusion The VMMC program’s impact and cost-effectiveness vary by age-targeting strategy. A strategy focusing on men ages 15–34 will maximize program benefits. However, because clients older than 25 access VMMC services at low rates, South Africa could consider promoting demand among men ages 25–34, without denying services to those in other age groups. Uncertainty in the provincial estimates makes them

  10. Development of medium-size half-mask facepiece for male workers at a shipyard and its fit performance in Korea.

    PubMed

    Han, Don-Hee; Kim, David

    2014-01-01

    Ten years ago, three differently sized half-mask facepiece prototypes were constructed from silicon using computer graphics and statistical analysis to fit them according to Korean facial dimensions. The purpose of this study was to complete the medium-size half-mask respirator based on the prototype, which would provide an adequate fit performance for male workers at a shipyard, Hyundai Samho Heavy Industry Co., in Korea. The complete respirator--the hardness 55--was manufactured with existing accessories such as a filter, exhalation valve, and strap attached. The fit performance test was conducted by performing a quantitative fit-test on 48 male subjects: workers who usually wear half-mask respirators (Dobulife Tech Co., Model DM-911, Gwangju, Gyeonggi-do, Korea). The results showed that the hardness 55 provided male subject workers with much better fit performance than the existing mask constructed by the same company. Because softness of the material of the facepiece, in particular the inner part, influenced faceseal leakage, further research on developing better-fit respirator facepieces should consider carefully the fine control of material softness. PMID:24467771

  11. Associations of food group and nutrient intake, diet quality, and meal sizes between adults and children in the same household: a cross-sectional analysis of U.S. households

    PubMed Central

    2011-01-01

    Background One might assume that individuals living in the same household have similar dietary intakes of food groups and nutrients. However, the manner in which an adult's dietary intake affects children's food consumption, diet quality (defined as meeting intake recommendations), and meal sizes is understudied to date. The objective of this study was to estimate these relationships between minor children and the female or male head of household. Methods Dietary intakes of one randomly selected child of each age group (2-5, 6-11, or 12-18 years old (n = 2,380)) and that of the female/male head of household ((HH), proxy for mother and father) using multiple 24-hour recalls from the Continuing Survey of Food Intake by Individuals (CSFII) 1994-1996 was coded to reflect food group and nutrient density (servings/grams per 1,000 kcal). Linear or logistic regression models were used to determine the association between intakes, whether individuals' diets trended toward meeting her/his intake recommendations, and whether individuals were in the highest quintile for food group densities at four distinct eating occasions (breakfast, brunch/lunch, supper/dinner, or other) in each subject group. Stata's survey commands were used to fit linear or logistic regression models and obtain adjusted regression coefficients or odds ratios. Results Associations between food group/nutrient densities were significant but weak to moderate. Adults with diets that trended toward meeting their intake recommendations doubled the odds for children to have diets that trended toward meeting the recommendations; for many meals, adults consuming in the highest quintile for food group density predicted that children's intakes were also in the highest quintile. Conclusions Female and male adults living in the same household significantly affect children's food group and nutrient intakes, diet quality, and meal sizes. There is an urgent need for in-depth analysis to elucidate the underlying

  12. The Relative Effects of Group Size on Reading Progress of Older Students with Reading Difficulties

    ERIC Educational Resources Information Center

    Vaughn, Sharon; Wanzek, Jeanne; Wexler, Jade; Barth, Amy; Cirino, Paul T.; Fletcher, Jack; Romain, Melissa; Denton, Carolyn A.; Roberts, Greg; Francis, David

    2010-01-01

    This study reports findings on the relative effects from a yearlong secondary intervention contrasting large-group, small-group, and school-provided interventions emphasizing word study, vocabulary development, fluency, and comprehension with seventh- and eighth-graders with reading difficulties. Findings indicate that few statistically…

  13. The effects of group size on aggression when mixing unacquainted sows in outdoor paddocks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aggression is a challenge when pigs are kept in groups. Sows fight at mixing when space is limited but this project sought to determine the amount and type of aggression observed when unacquainted Berkshire sows were mixed in pairs or in two established sub-groups of three in outdoor paddocks. Treat...

  14. Defensive responses by a social caterpillar are tailored to different predators and change with larval instar and group size

    NASA Astrophysics Data System (ADS)

    McClure, Melanie; Despland, Emma

    2011-05-01

    Gregariousness in animals is widely accepted as a behavioral adaptation for protection from predation. However, predation risk and the effectiveness of a prey's defense can be a function of several other factors, including predator species and prey size or age. The objective of this study was to determine if the gregarious habit of Malacosoma disstria caterpillars is advantageous against invertebrate natural enemies, and whether it is through dilution or cooperative defenses. We also examined the effects of larval growth and group size on the rate and success of attacks. Caterpillars of M. disstria responded with predator-specific behaviors, which led to increased survival. Evasive behaviors were used against stinkbugs, while thrashing by fourth instar caterpillars and holding on to the silk mat by second instar caterpillars was most efficient against spider attacks. Collective head flicking and biting by groups of both second and fourth instar caterpillars were observed when attacked by parasitoids. Increased larval size decreased the average number of attacks by spiders but increased the number of attacks by both stinkbugs and parasitoids. However, increased body size decreased the success rate of attacks by all three natural enemies and increased handling time for both predators. Larger group sizes did not influence the number of attacks from predators but increased the number of attacks and the number of successful attacks from parasitoids. In all cases, individual risk was lower in larger groups. Caterpillars showed collective defenses against parasitoids but not against the walking predators. These results show that caterpillars use different tactics against different natural enemies. Overall, these tactics are both more diverse and more effective in fourth instar than in second instar caterpillars, confirming that growth reduces predation risk. We also show that grouping benefits caterpillars through dilution of risk, and, in the case of parasitoids, through

  15. Scent-marking and sexual activity may reflect social hierarchy among group-living male Mongolian gerbils (Meriones unguiculatus).

    PubMed

    Shimozuru, Michito; Kikusui, Takefumi; Takeuchi, Yukari; Mori, Yuji

    2006-12-30

    Social hierarchy plays an important role in the lives of gregarious species. We investigated how social hierarchy between male Mongolian gerbils (Meriones unguiculatus) housed together before sexual maturity affected their scent-marking behavior, endocrine status and physical traits as adults. The social rank between paired males was assessed based on sexual activity in adulthood at 18 and 20 weeks of age. In most cases, the male that showed higher sexual activity at 18 weeks also exhibited greater sexual performance at 20 weeks, suggesting a precedence relationship between paired males regarding reproductive opportunity. Sexually active males scent-marked more often than their cage mate, particularly after a sexual experience. No significant differences in physical traits (e.g., the weight of the ventral gland, testes and adrenal glands) or endocrine status (e.g., fecal testosterone and corticosterone levels) were found between the two males. These findings suggest that social rank between familiar males formed during cohabitation, and rank was closely correlated with scent-marking activity, but not with endocrine status. PMID:16959280

  16. Childhood Adversity Among Institutionalized Male Juvenile Offenders and Other High-Risk Groups Without Offense Records in Portugal.

    PubMed

    Pinto, Ricardo José; Fernandes, Ana Isabel; Mesquita, Cristina; Maia, Ângela Costa

    2015-01-01

    The literature has shown that delinquent adolescents report high rates of childhood adversity and family dysfunction. However, it is important to know both the degree of adversity among delinquent adolescents in comparison with other high-risk samples and the contribution of each single form of adversity to this comparison. The purpose of this study was to evaluate childhood adversity, psychopathology, and risk behaviors among 4 high-risk groups, including incarcerated delinquent youths. The participants were 120 male youths between 13 and 19 years old (M = 16.18, SD = 1.26), including 30 youths who were arrested and held in detention centers as a consequence of violent crimes; 30 youths who were identified by Child Protective Services (CPS) and remained with their families; 30 youths who were identified by CPS, removed from their homes, and placed in child and youth residential care; and 30 youths who were randomly selected from schools. The incarcerated youths reported significantly more adversity, global psychopathology, and global index of risk behaviors. When considering each risk behavior, the incarcerated youths reported higher percentages of alcohol abuse, drug use, early smoking initiation, physical assault, carrying weapons, early initiation of sexual intercourse, sexual intercourse under the influence of drugs, and sexual intercourse without condom use. The logistic regression analyses showed that only emotional neglect was significantly associated with delinquency. This study suggests that delinquent youths are exposed to a great magnitude of adversities in childhood, with emotional neglect as an independent risk factor for delinquency. In addition, these youths have higher rates of psychopathology and risk behaviors compared to other high-risk samples. PMID:26159627

  17. Group size modifies the patterns and muscle carbohydrate effects of aggression in Betta splendens.

    PubMed

    Haller, J

    1992-08-01

    Aggressive encounters of previously isolated individuals were investigated in dyads and groups of five. Fights were longer and more intense when they were performed in dyads compared to fights involving five fishes. During aggressive encounters, an elevation in carbohydrate catabolism was noticed in both dyads and groups. Losing a fight resulted in a reduction in glycogen content and an increase in glycogen synthesis. Similar changes in winners did not appear; thus, the metabolic response in losers was different from that noticed in winners, both in dyads and groups. In dyadic contest winners, a marked increase in the free glucose content and glucose consumption was noticed (without changes in losers). In groups, free glucose content of the winners was not modified, while glucose consumption was enhanced both in winners and losers. Thus, the differences existing between winners and losers were greater in dyads compared to those noticed in groups. The energy cost of aggression seems to be different in dyads compared to groups of five. The rate of glucose oxidation was strongly reduced in dyads (there were no differences between winners and losers in this respect), while in groups, this parameter was not modified. PMID:1523255

  18. Effects of Violations of Data Set Assumptions When Using the Analysis of Variance and Covariance with Unequal Group Sizes.

    ERIC Educational Resources Information Center

    Johnson, Colleen Cook; Rakow, Ernest A.

    This research explored the degree to which group sizes can differ before the robustness of analysis of variance (ANOVA) and analysis of covariance (ANCOVA) are jeopardized. Monte Carlo methodology was used, allowing for the experimental investigation of potential threats to robustness under conditions common to researchers in education. The…

  19. Reciprocal Relations between Student-Teacher Relationship and Children's Behavioral Problems: Moderation by Child-Care Group Size

    ERIC Educational Resources Information Center

    Skalická, Vera; Belsky, Jay; Stenseng, Frode; Wichstrøm, Lars

    2015-01-01

    In this Norwegian study, bidirectional relations between children's behavior problems and child-teacher conflict and closeness were examined, and the possibility of moderation of these associations by child-care group size was tested. Eight hundred and nineteen 4-year-old children were followed up in first grade. Results revealed reciprocal…

  20. Comparisons of Improvement-Over-Chance Effect Sizes for Two Groups under Variance Heterogeneity and Prior Probabilities

    ERIC Educational Resources Information Center

    Henson, Robin K.; Natesan, Prathiba; Axelson, Erika D.

    2014-01-01

    The authors examined the distributional properties of 3 improvement-over-chance, I, effect sizes each derived from linear and quadratic predictive discriminant analysis and from logistic regression analysis for the 2-group univariate classification. These 3 classification methods (3 levels) were studied under varying levels of data conditions,…

  1. The Effect of Computer-Assisted Cooperative Learning Methods and Group Size on the EFL Learners' Achievement in Communication Skills

    ERIC Educational Resources Information Center

    AbuSeileek, Ali Farhan

    2012-01-01

    This study explored the effect of cooperative learning small group size and two different instructional modes (positive interdependence vs. individual accountability) on English as a Foreign Language (EFL) undergraduate learners' communication skills (speaking and writing) achievement in computer-based environments. The study also examined the…

  2. A Note on Confidence Intervals for Two-Group Latent Mean Effect Size Measures

    ERIC Educational Resources Information Center

    Choi, Jaehwa; Fan, Weihua; Hancock, Gregory R.

    2009-01-01

    This note suggests delta method implementations for deriving confidence intervals for a latent mean effect size measure for the case of 2 independent populations. A hypothetical kindergarten reading example using these implementations is provided, as is supporting LISREL syntax. (Contains 1 table.)

  3. Randomized Controlled Trial of the ShangRing for Adult Medical Male Circumcision: Safety, Effectiveness, and Acceptability of Using 7 Versus 14 Device Sizes

    PubMed Central

    Zulu, Robert; Linyama, David; Long, Sarah; Nonde, Thikazi Jere; Lai, Jaim Jou; Kashitala, Joshua; Veena, Valentine; Kasonde, Prisca

    2016-01-01

    Objectives: To assess the safety, effectiveness, and acceptability of providing a reduced number of ShangRing sizes for adult voluntary medical male circumcision (VMMC) within routine service delivery in Lusaka, Zambia. Methods: We conducted a randomized controlled trial and enrolled 500 HIV-negative men aged 18–49 years at 3 clinics. Participants were randomized to 1 of 2 study arms (Standard Sizing arm vs Modified Sizing arm) in a 1:1 ratio. All 14 adult ShangRing sizes (40–26 mm inner diameter, each varying by 1 mm) were available in the Standard Sizing arm; the Modified Sizing arm used every other size (40, 38, 36, 34, 32, 30, 28 mm inner diameter). Each participant was scheduled for 2 follow-up visits: the removal visit (day 7 after placement) and the healing check visit (day 42 after placement), when they were evaluated for adverse events (AEs), pain, and healing. Results: Four hundred and ninety-six men comprised the analysis population, with 255 in the Standard Sizing arm and 241 in the Modified Sizing arm. Three men experienced a moderate or severe AEs (0.6%), including 2 in the Standard Sizing arm (0.8%) and 1 in the Modified Sizing arm (0.4%). 73.2% of participants were completely healed at the scheduled day 42 healing check visit, with similar percentages across study arms. Virtually all (99.6%) men, regardless of study arm, stated that they were very satisfied or satisfied with the appearance of their circumcised penis, and 98.6% stated that they would recommend ShangRing circumcision to family/friends. Conclusions: The moderate/severe AE rate was low and similar in the 2 study arms, suggesting that provision of one-half the number of adult device sizes is sufficient for safe service delivery. Effectiveness, time to healing, and acceptability were similar in the study arms. The simplicity of the ShangRing technique, and its relative speed, could facilitate VMMC program goals. In addition, sufficiency of fewer device sizes would simplify logistics

  4. Ehd4 is required to attain normal pre-pubertal testis size but dispensable for fertility in male mice

    PubMed Central

    George, Manju; Rainey, Mark A.; Naramura, Mayumi; Ying, GuoGuang; Harms, Don W.; Vitaterna, Martha H.; Doglio, Lynn; Crawford, Susan E.; Hess, Rex A.; Band, Vimla; Band, Hamid

    2010-01-01

    The four highly homologous members of the C-terminal EH domain-containing (EHD) protein family (EHD1-4) regulates endocytic recycling. To delineate the role of EHD4 in normal physiology and development, mice with a conditional knockout of the Ehd4 gene were generated. PCR of genomic DNA and Western blotting of organ lysates from Ehd4−/− mice confirmed EHD4 deletion. Ehd4−/− mice were viable and born at expected Mendelian ratios; however, males showed a 50% reduction in testis weight, obvious from postnatal day 31. An early (day 10) increase in germ cell proliferation and apoptosis and a later increase in apoptosis (day 31) were seen in the Ehd4−/− testis. Other defects included a progressive reduction in seminiferous tubule diameter, dysregulation of seminiferous epithelium and head abnormalities in elongated spermatids. As a consequence, lower sperm counts and reduced fertility were observed in Ehd4−/− males. Interestingly, EHD protein expression was seen to be temporally regulated in the testis and levels peaked between days 10 and 15. In the adult testis, EHD4 was highly expressed in primary spermatocytes and EHD4 deletion altered the levels of other EHD proteins in an age-dependent manner. We conclude that high levels of EHD1in the adult Ehd4−/− testis functionally compensate for lack of EHD4 and prevents the development of severe fertility defects. Our results suggest a role for EHD4 in the proper development of post-mitotic and post-meiotic germ cells and implicate EHD protein-mediated endocytic recycling as an important process in germ cell development and testis function. PMID:20213691

  5. Part II: Differences between Sexually Victimized and Nonsexually Victimized Male Adolescent Sexual Abusers and Delinquent Youth--Further Group Comparisons of Developmental Antecedents and Behavioral Challenges

    ERIC Educational Resources Information Center

    Leibowitz, George S.; Burton, David L.; Howard, Alan

    2012-01-01

    In a recent paper published in the "Journal of Child Sexual Abuse," we assessed the differences between sexually victimized and nonsexually victimized male adolescent sexual abusers (Burton, Duty, & Leibowitz, 2011). We found that the sexually victimized group had more severe developmental antecedents (e.g., trauma and early exposure to…

  6. The effect of body coloration and group size on social partner preferences in female fighting fish (Betta splendens).

    PubMed

    Blakeslee, C; McRobert, S P; Brown, A C; Clotfelter, E D

    2009-02-01

    Females of the fighting fish Betta splendens have been shown to associate with other B. splendens females in a manner reminiscent of shoaling behavior. Since body coloration varies dramatically in this species, and since body coloration has been shown to affect shoalmate choice in other species of fish, we examined the influence of body coloration on association preferences in female B. splendens. In dichotomous choice tests, B. splendens females spent more time swimming near groups of females (regardless of coloration) than swimming near an empty chamber, and chose to swim near fish of similar coloration to their own when choosing between two distinctly colored groups of females. When examining the interplay between body coloration and group size, focal fish spent more time swimming near larger groups (N=5) of similarly colored fish than swimming near an individual female of similar coloration. However, focal fish showed no preference when presented with an individual female of similar coloration and a larger group of females of dissimilar coloration. These results suggest that association choices in B. splendens females are strongly affected by both body coloration and by group size. PMID:19059314

  7. Becoming a Scientist: The Effects of Work-Group Size and Organizational Climate

    ERIC Educational Resources Information Center

    Louis, Karen Seashore; Holdsworth, Janet M.; Anderson, Melissa S.; Campbell, Eric G.

    2007-01-01

    The purpose of this article is to explore the effects of organizational and work-group characteristics on the socialization of new scientists. It focuses on the experiences of graduate students and postdoctoral fellows in science. The authors chose to look at outcomes that reflect behaviors (early productivity) and attitudes (willingness to share…

  8. Sample Sizes for Two-Group Second-Order Latent Growth Curve Models

    ERIC Educational Resources Information Center

    Wanstrom, Linda

    2009-01-01

    Second-order latent growth curve models (S. C. Duncan & Duncan, 1996; McArdle, 1988) can be used to study group differences in change in latent constructs. We give exact formulas for the covariance matrix of the parameter estimates and an algebraic expression for the estimation of slope differences. Formulas for calculations of the required sample…

  9. The effects of group size on aggression when mixing unacquainted sows in indoor pens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the US swine industry moves towards group housing sows, it is important to increase our understanding of aggression. Sows fight at mixing and this project sought to determine the amount and type of aggression observed when unacquainted York × Landrace sows were mixed in pairs or in two establishe...

  10. The Long and the Short of It: No Dietary Specialisation between Male and Female Western Sandpipers Despite Strong Bill Size Dimorphism

    PubMed Central

    Franks, Samantha E.; Fernández, Guillermo; Hodkinson, David J.; Kyser, T. Kurt; Lank, David B.

    2013-01-01

    Many bird species show spatial or habitat segregation of the sexes during the non-breeding season. One potential ecological explanation is that differences in bill morphology favour foraging niche specialisation and segregation. Western sandpipers Calidris mauri have pronounced bill size dimorphism, with female bills averaging 15% longer than those of males. The sexes differ in foraging behaviour and exhibit partial latitudinal segregation during the non-breeding season, with males predominant in the north and females in the south. Niche specialisation at a local scale might account for this broad geographic pattern, and we investigated whether longer-billed females and shorter-billed males occupy different foraging niches at 16 sites across the non-breeding range. We used stable-nitrogen (δ15N) isotope analysis of whole blood to test for dietary specialisation according to bill length and sex. Stable-nitrogen isotope ratios increase with trophic level. We predicted that δ15N values would increase with bill length and would be higher for females, which use a greater proportion of foraging behaviour that targets higher-trophic level prey. We used stable-carbon (δ13C) isotope analysis to test for habitat segregation according to bill length and sex. Stable-carbon isotope ratios vary between marine- and freshwater-influenced habitats. We predicted that δ13C values would differ between males and females if the sexes segregate between habitat types. Using a model selection approach, we found little support for a relationship between δ15N and either bill length or sex. There was some indication, however, that more marine δ13C values occur with shorter bill lengths. Our findings provide little evidence that male and female western sandpipers exhibit dietary specialisation as a function of their bill size, but indicate that the sexes may segregate in different habitats according to bill length at some non-breeding sites. Potential ecological factors underlying

  11. Bioaccumulation and depuration pattern of copper in different tissues of mystus vittatus, related to various size groups.

    PubMed

    Subathra, Sriramulu; Karuppasamy, Ramasamy

    2008-02-01

    The bioaccumulation pattern of copper (Cu) in gill, liver, kidney, and muscle of different sizes (fingerlings and adult age) of healthy Mystus vittatus when exposed to their respective sublethal concentrations of Cu-water, containing one-third 96-hr LC(50) level (6.20 and 15.95 mg L(-1)) for short-term (120 hr) and one-eighth 96-hr LC(50) level (2.33 and 5.98 mg L(-1)) for long-term experimentation, respectively, has been analyzed. The Cu shows a maximum deposition (p < 0.01) in the liver (82.12 and 70.65 microg/g) followed by gill (74.35 and 63.69 microg/g) and kidney (61.52 and 54.09 microg/g) both in fingerlings and adult fish, respectively, during 28 days of exposure. The lowest deposition of Cu is found to be 0.83 and 0.93 microg/g in fingerlings and 0.79 and 0.86 microg/g in adult muscle tissue during short-term (120 hr) and long-term (28 days) exposure periods, respectively. Comparing the accumulation of Cu on the two size groups at both exposure levels, it is obvious that the fingerlings showed higher Cu concentration in all tissues than those of adult fish. Another equally important finding is that the depuration of Cu by maintaining the bioaccumulated fish (long-term exposed group) of both size groups in quality dechlorinated ground water reveals that there is a significant (p < 0.05) reduction in Cu concentration in different tissues as the day passes. A comparison of the performance of the two size groups in respect of depuration clearly indicates that the fingerlings have taken 24-43 days (gill-kidney), whereas in mature fish it is 21-39 days (gill-kidney) to reach the level of control fish. Among the various tissues in both size groups, gill took the minimum number of days for complete recovery, whereas the muscle tissue did not significantly eliminate Cu even after 30 days of depuration. These data constitute a reference for future studies on the evolution of Cu accumulation and elimination tendency in relation to different size groups of fish in the

  12. Age-Group-Specific Associations between the Severity of Obstructive Sleep Apnea and Relevant Risk Factors in Male and Female Patients

    PubMed Central

    Deng, Xingqi; Gu, Wei; Li, Yanyan; Liu, Mei; Li, Yan; Gao, Xiwen

    2014-01-01

    Aim To seek accurate and credible correlation manner between gender, age, and obesity; and the severity of obstructive sleep apnea (OSA) in large-scale population. Methods Totals of 1,975 male and 378 female OSA patients were sequentially recruited. Centralized covariant tendencies between age, body mass index (BMI), and waist hip ratio (WHR); and OSA severity, were explored in a gender-specific manner via multiple statistical analyses. The accuracies of observed correlations were further evaluated by adaptive multiple linear regression. Results All of age, BMI, WHR, smoking, drinking, and OSA severity differed between males and females. BMI and WHR were positively and (approximately) linearly associated with OSA severity in both males and females. Restricted cubic spline analysis was more effective than was the Pearson correlation approach in correlating age with AHI, and provided age crossover points allowing further piecewise linear modeling for both males and females. Multiple linear regression showed that increasing age was associated with OSA exacerbation in males aged ≤40 years and in females aged 45–53 years. BMI, WHR, and diabetes were independently associated with OSA severity in males with age-group-specific pattern. In females, only BMI was associated with OSA severity at all ages. Conclusions In male patients, BMI and WHR are prominent risk factors for OSA exacerbation. Age and diabetes are associated with OSA severity in males of particular ages. In females, BMI is also a prominent risk factor for severe OSA, and OSA severity increased with age in the range 45–53 years. PMID:25211035

  13. Fibroblast Growth Factor-2 Isoform (Low Molecular Weight/18 kDa) Overexpression in Preosteoblast Cells Promotes Bone Regeneration in Critical Size Calvarial Defects in Male Mice

    PubMed Central

    Xiao, Liping; Ueno, Daisuke; Catros, Sylvain; Homer-Bouthiette, Collin; Charles, Lyndon; Kuhn, Liisa

    2014-01-01

    Repair of bone defects remains a significant clinical problem. Bone morphogenetic protein 2 (BMP2) is US Food and Drug Administration–approved for fracture healing but is expensive and has associated morbidity. Studies have shown that targeted overexpression of the 18-kDa low-molecular-weight fibroblast growth factor 2 isoform (LMW) by the osteoblastic lineage of transgenic mice increased bone mass. This study tested the hypotheses that overexpression of LMW would directly enhance healing of a critical size calvarial bone defect in mice and that this overexpression would have a synergistic effect with low-dose administration of BMP2 on critical size calvarial bone defect healing. Bilateral calvarial defects were created in LMW transgenic male mice and control/vector transgenic (Vector) male mice and scaffold with or without BMP2 was placed into the defects. New bone formation was assessed by VIVA-computed tomography of live animals over a 27-week period. Radiographic and computed tomography analysis revealed that at all time points, healing of the defect was enhanced in LMW mice compared with that in Vector mice. Although the very low concentration of BMP2 did not heal the defect in Vector mice, it resulted in complete healing of the defect in LMW mice. Histomorphometric and gene analysis revealed that targeted overexpression of LMW in osteoblast precursors resulted in enhanced calvarial defect healing due to increased osteoblast activity and increased canonical Wnt signaling. PMID:24424065

  14. Substituted Septithiophenes with End Groups of Different Size: Packing and Frustration in Bulk and Thin Films.

    PubMed

    de Jeu, Wim H; Rahimi, Khosrow; Ziener, Ulrich; Vill, Roman; Herzig, Eva M; Müller-Buschbaum, Peter; Möller, Martin; Mourran, Ahmed

    2016-02-16

    We report on three different liquid crystalline compounds with a central septithiophene core and alkylated end groups of strongly increasing bulkiness. In principle, the thiophene cores prefer to pack parallel to optimize their π-π interactions, which becomes sterically impossible for the bulkier end groups. Using X-ray diffraction, we find that the way out of this packing dilemma is toward liquid-crystal phases of higher dimensionality in the order smectic → columnar ↔ bicontinuous cubic. For the smectic phase, packing in a monolayer is no problem; for the other ones packing considerations become more stringent in films due to the boundaries. Surface X-ray techniques and atomic force microscopy indicate an appreciable difference between monolayer and three-layer films, in which the monolayers appear to escape from packing frustration by generating superstructures. We propose a basic structure of columns parallel to the substrate that provides a compromise between preserving some π-π interactions and packing the bulky alkyl groups. PMID:26807677

  15. Leading Causes of Death in Males United States, 2010

    MedlinePlus

    ... Native Males by Age Group, 2013 Asian or Pacific Islander Males by Age Group, 2013 Hispanic Males ... Native Males by Age Group, 2011 Asian or Pacific Islander Males by Age Group, 2011 Hispanic Males ...

  16. Long-term resource variation and group size: A large-sample field test of the Resource Dispersion Hypothesis

    PubMed Central

    Johnson, Dominic DP; Baker, Samantha; Morecroft, Michael D; Macdonald, David W

    2001-01-01

    Background The Resource Dispersion Hypothesis (RDH) proposes a mechanism for the passive formation of social groups where resources are dispersed, even in the absence of any benefits of group living per se. Despite supportive modelling, it lacks empirical testing. The RDH predicts that, rather than Territory Size (TS) increasing monotonically with Group Size (GS) to account for increasing metabolic needs, TS is constrained by the dispersion of resource patches, whereas GS is independently limited by their richness. We conducted multiple-year tests of these predictions using data from the long-term study of badgers Meles meles in Wytham Woods, England. The study has long failed to identify direct benefits from group living and, consequently, alternative explanations for their large group sizes have been sought. Results TS was not consistently related to resource dispersion, nor was GS consistently related to resource richness. Results differed according to data groupings and whether territories were mapped using minimum convex polygons or traditional methods. Habitats differed significantly in resource availability, but there was also evidence that food resources may be spatially aggregated within habitat types as well as between them. Conclusions This is, we believe, the largest ever test of the RDH and builds on the long-term project that initiated part of the thinking behind the hypothesis. Support for predictions were mixed and depended on year and the method used to map territory borders. We suggest that within-habitat patchiness, as well as model assumptions, should be further investigated for improved tests of the RDH in the future. PMID:11511326

  17. Group Size and Nest Spacing Affect Buggy Creek Virus (Togaviridae: Alphavirus) Infection in Nestling House Sparrows

    PubMed Central

    O'Brien, Valerie A.; Brown, Charles R.

    2011-01-01

    The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house sparrows are seriously affected by BCRV. For house sparrows occupying swallow nesting colonies in western Nebraska, USA, the prevalence of BCRV in nestling sparrows increased with sparrow colony size at a site but decreased with the number of cliff swallows present. If one nestling in a nest was infected with the virus, there was a greater likelihood that one or more of its nest-mates would also be infected than nestlings chosen at random. The closer a nest was to another nest containing infected nestlings, the greater the likelihood that some of the nestlings in the focal nest would be BCRV-positive. These results illustrate that BCRV represents a cost of coloniality for a vertebrate host (the house sparrow), perhaps the first such demonstration for an arbovirus, and that virus infection is spatially clustered within nests and within colonies. The decreased incidence of BCRV in sparrows as cliff swallows at a site increased reflects the “dilution effect,” in which virus transmission is reduced when a vector switches to feeding on a less competent vertebrate host. PMID:21966539

  18. Line transect estimation of population size: the exponential case with grouped data

    USGS Publications Warehouse

    Anderson, D.R.; Burnham, K.P.; Crain, B.R.

    1979-01-01

    Gates, Marshall, and Olson (1968) investigated the line transect method of estimating grouse population densities in the case where sighting probabilities are exponential. This work is followed by a simulation study in Gates (1969). A general overview of line transect analysis is presented by Burnham and Anderson (1976). These articles all deal with the ungrouped data case. In the present article, an analysis of line transect data is formulated under the Gates framework of exponential sighting probabilities and in the context of grouped data.

  19. Chondrule size and related physical properties: A compilation and evaluation of current data across all meteorite groups

    NASA Astrophysics Data System (ADS)

    Friedrich, Jon M.; Weisberg, Michael K.; Ebel, Denton S.; Biltz, Alison E.; Corbett, Bernadette M.; Iotzov, Ivan V.; Khan, Wajiha S.; Wolman, Matthew D.

    2015-12-01

    The examination of the physical properties of chondrules has generally received less emphasis than other properties of meteorites such as their mineralogy, petrology, and chemical and isotopic compositions. Among the various physical properties of chondrules, chondrule size is especially important for the classification of chondrites into chemical groups, since each chemical group possesses a distinct size-frequency distribution of chondrules. Knowledge of the physical properties of chondrules is also vital for the development of astrophysical models for chondrule formation, and for understanding how to utilize asteroidal resources in space exploration. To examine our current knowledge of chondrule sizes, we have compiled and provide commentary on available chondrule dimension literature data. We include all chondrite chemical groups as well as the acapulcoite primitive achondrites, some of which contain relict chondrules. We also compile and review current literature data for other astrophysically-relevant physical properties (chondrule mass and density). Finally, we briefly examine some additional physical aspects of chondrules such as the frequencies of compound and 'cratered' chondrules. A purpose of this compilation is to provide a useful resource for meteoriticists and astrophysicists alike.

  20. Genetic determination of telomere size in humans: A twin study of three age groups

    SciTech Connect

    Slagboom, P.E.; Droog, S.; Boomsma, D.I.

    1994-11-01

    Reduction of telomere length has been postulated to be a casual factor in cellular aging. Human telomeres terminate in tandemly arranged repeat arrays consisting of the (TTAGGG) motif. The length of these arrays in cells from human mitotic tissues is inversely related to the age of the donor, indicating telomere reduction with age. In addition to telemore length differences between different age cohorts, considerable variation is present among individuals of the same age. To investigate whether this variation can be ascribed to genetic influences, we have measured the size of terminal restriction fragments (TRFs) in HaeIII-digested genomic DNA from 123 human MZ and DZ twin pairs 2-95 years of age. The average rate of telomere shortening was 31 bp/year, which is similar to that observed by others. Statistical analysis in 115 pairs 2-63 years of age indicates a 78% heritability for mean TRF length in this age cohort. The individual differences in mean TRF length in blood, therefore, seem to a large extent to be genetically determined. 24 refs., 4 figs., 2 tabs.

  1. Assessing sources of error in comparative analyses of primate behavior: Intraspecific variation in group size and the social brain hypothesis.

    PubMed

    Sandel, Aaron A; Miller, Jordan A; Mitani, John C; Nunn, Charles L; Patterson, Samantha K; Garamszegi, László Zsolt

    2016-05-01

    Phylogenetic comparative methods have become standard for investigating evolutionary hypotheses, including in studies of human evolution. While these methods account for the non-independence of trait data due to phylogeny, they often fail to consider intraspecific variation, which may lead to biased or erroneous results. We assessed the degree to which intraspecific variation impacts the results of comparative analyses by investigating the "social brain" hypothesis, which has provided a framework for explaining complex cognition and large brains in humans. This hypothesis suggests that group life imposes a cognitive challenge, with species living in larger social groups having comparably larger neocortex ratios than those living in smaller groups. Primates, however, vary considerably in group size within species, a fact that has been ignored in previous analyses. When within-species variation in group size is high, the common practice of using a mean value to represent the species may be inappropriate. We conducted regression and resampling analyses to ascertain whether the relationship between neocortex ratio and group size across primate species persists after controlling for within-species variation in group size. We found that in a sample of 23 primates, 70% of the variation in group size was due to between-species variation. Controlling for within-species variation in group size did not affect the results of phylogenetic analyses, which continued to show a positive relationship between neocortex ratio and group size. Analyses restricted to non-monogamous primates revealed considerable intraspecific variation in group size, but the positive association between neocortex ratio and group size remained even after controlling for within-species variation in group size. Our findings suggest that the relationship between neocortex size and group size in primates is robust. In addition, our methods and associated computer code provide a way to assess and account for

  2. Effects of box size, frequency of lifting, and height of lift on maximum acceptable weight of lift and heart rate for male university students in Iran

    PubMed Central

    Abadi, Ali Salehi Sahl; Mazlomi, Adel; Saraji, Gebraeil Nasl; Zeraati, Hojjat; Hadian, Mohammad Reza; Jafari, Amir Homayoun

    2015-01-01

    Introduction In spite of the widespread use of automation in industry, manual material handling (MMH) is still performed in many occupational settings. The emphasis on ergonomics in MMH tasks is due to the potential risks of workplace accidents and injuries. This study aimed to assess the effect of box size, frequency of lift, and height of lift on maximum acceptable weight of lift (MAWL) on the heart rates of male university students in Iran. Methods This experimental study was conducted in 2015 with 15 male students recruited from Tehran University of Medical Sciences. Each participant performed 18 different lifting tasks that involved three lifting frequencies (1lift/min, 4.3 lifts/min and 6.67 lifts/min), three lifting heights (floor to knuckle, knuckle to shoulder, and shoulder to arm reach), and two box sizes. Each set of experiments was conducted during the 20 min work period using the free-style lifting technique. The working heart rates (WHR) were recorded for the entire duration. In this study, we used SPSS version 18 software and descriptive statistical methods, analysis of variance (ANOVA), and the t-test for data analysis. Results The results of the ANOVA showed that there was a significant difference between the mean of MAWL in terms of frequencies of lifts (p = 0.02). Tukey’s post hoc test indicated that there was a significant difference between the frequencies of 1 lift/minute and 6.67 lifts/minute (p = 0. 01). There was a significant difference between the mean heart rates in terms of frequencies of lifts (p = 0.006), and Tukey’s post hoc test indicated a significant difference between the frequencies of 1 lift/minute and 6.67 lifts/minute (p = 0.004). But, there was no significant difference between the mean of MAWL and the mean heart rate in terms of lifting heights (p > 0.05). The results of the t-test showed that there was a significant difference between the mean of MAWL and the mean heart rate in terms of the sizes of the two boxes (p

  3. Crystalline state photochromism of 3-furylfulgides: impact of size and bond flexibility of the non-aromatic alkylidene group.

    PubMed

    Hettiarachchi, Champika V; Weerasekara, Roshan K; Uekusa, Hidehiro

    2015-10-01

    3-Furylfulgides are photochromic compounds showing high thermal stability in their closed forms. However, their photochromic properties in the solid state should be improved further to fabricate molecular devices. Understanding how the size and the flexibility of the non-aromatic alkylidene moiety alter the crystalline state photochromic properties is also important here, as the alkylidene group is directly involved in the photochromic ring closing and opening reactions. The synthesis of four 3-furylfulgides composed of different alkylidene groups (rigid isopropyl, flexible 2-butyl, rigid cyclopentyl and flexible cyclohexyl), their crystal structures and structure-photochromic property correlation in the crystalline state are reported here. Crystallographic data along with reaction cavity volumes calculated using the program CAVITY [Ohashi et al. (1981), J. Am. Chem. Soc. 103, 5805-5812] disclosed that fulgides with flexible groups at the ring closing site have more free volume around the reactive area in the crystal lattice, which can provide more space for the atomic movements in the reaction and flexibility can reduce the strain built up in the closed C-isomers by making conformations. According to UV-vis spectroscopic data, a higher yield of C-isomers and a better fatigue resistance were obtained for the 3-furylfulgide with the largest and flexible cyclohexyl group showing greater photochromic properties in the crystalline state than the fulgide containing the smallest and rigid isopropyl group. PMID:26428403

  4. Unit-level voluntary turnover rates and customer service quality: implications of group cohesiveness, newcomer concentration, and size.

    PubMed

    Hausknecht, John P; Trevor, Charlie O; Howard, Michael J

    2009-07-01

    Despite substantial growth in the service industry and emerging work on turnover consequences, little research examines how unit-level turnover rates affect essential customer-related outcomes. The authors propose an operational disruption framework to explain why voluntary turnover impairs customers' service quality perceptions. On the basis of a sample of 75 work units and data from 5,631 employee surveys, 59,602 customer surveys, and organizational records, results indicate that unit-level voluntary turnover rates are negatively related to service quality perceptions. The authors also examine potential boundary conditions related to the disruption framework. Of 3 moderators studied (group cohesiveness, group size, and newcomer concentration), results show that turnover's negative effects on service quality are more pronounced in larger units and in those with a greater concentration of newcomers. PMID:19594245

  5. Effects of Stocking Density or Group Size on Intake, Growth, and Meat Quality of Hanwoo Steers (Bos taurus coreanae).

    PubMed

    Lee, Sang Moo; Kim, Jae Yeon; Kim, Eun Joong

    2012-11-01

    This study was conducted to investigate the effects of stocking density or group size on feed intake, daily gain, and carcass characteristics of Hanwoo (Korean indigenous breed) steers reared from 7 months to 31 months of age. Thirty Hanwoo steers were divided into four groups with three replicates each (a total of 12 pens). In each group, one (G1), two (G2), three (G3), and four steers (G4) per pen were allocated as treatments. Pen size was 32.0 m(2), and therefore Hanwoo steers in G1, G2, G3, and G4 were reared under different space allowances, i.e. 32.0, 16.0, 10.6, and 8.0 m(2)/steer, respectively. Steers were reared following a conventional beef cattle management method in Korea, and were offered a fixed amount of commercial concentrate with ad libitum forages. Results were subjected to analysis of variance with stocking density as the main effect, and significance was declared at p<0.05. Although total feed intake was not significantly altered, it numerically increased in animals of low stocking density (G1) compared to those subjected to high stocking density treatment (i.e. G4). Feed conversion ratio was higher (p<0.05) in G3 compared to G1 and G2. Animals in G1 (low stocking density) grew faster (p<0.05) than those of high stocking density (G3 and G4). Back fat thickness, meat yield index, and meat yield grade were similar among all levels of stocking density. However, longissimus muscle area was larger in G1 and G2 (p<0.01) compared to G3 and G4, and animals in G3 produced smaller carcasses (p<0.05). Carcass quality traits, including marbling score, meat color, fat color, texture, maturity and meat quality grade, as determined by a group of experts, were not significantly different among the treatments. In conclusion, lower stocking density resulted in increased feed efficiency, daily gain, and carcass weight in Hanwoo steers. However it remains unclear whether such differences are the results of stocking density or group size, or a combination of both

  6. Warring arthropod societies: Social spider colonies can delay annihilation by predatory ants via reduced apparency and increased group size.

    PubMed

    Keiser, Carl N; Wright, Colin M; Pruitt, Jonathan N

    2015-10-01

    Sociality provides individuals with benefits via collective foraging and anti-predator defense. One of the costs of living in large groups, however, is increased apparency to natural enemies. Here, we test how the individual-level and collective traits of spider societies can increase the risk of discovery and death by predatory ants. We transplanted colonies of the social spider Stegodyphus dumicola into a habitat dense with one of their top predators, the pugnacious ant Anoplolepis custodiens. With three different experiments, we test how colony-wide survivorship in a predator-dense habitat can be altered by colony apparency (i.e., the presence of a capture web), group size, and group composition (i.e., the proportion of bold and shy personality types present). We also test how spiders' social context (i.e., living solitarily vs. among conspecifics) modifies their behaviour toward ants in their capture web. Colonies with capture webs intact were discovered by predatory ants on average 25% faster than colonies with the capture web removed, and all discovered colonies eventually collapsed and succumbed to predation. However, the lag time from discovery by ants to colony collapse was greater for colonies containing more individuals. The composition of individual personality types in the group had no influence on survivorship. Spiders in a social group were more likely to approach ants caught in their web than were isolated spiders. Isolated spiders were more likely to attack a safe prey item (a moth) than they were to attack ants and were more likely to retreat from ants after contact than they were after contact with moths. Together, our data suggest that the physical structures produced by large animal societies can increase their apparency to natural enemies, though larger groups can facilitate a longer lag time between discovery and demise. Lastly, the interaction between spiders and predatory ants seems to depend on the social context in which spiders reside

  7. Is legal status impacting outcomes of group therapy for posttraumatic stress disorder with male asylum seekers and refugees from Iran and Afghanistan?

    PubMed Central

    2013-01-01

    Background Legal status and other resettlement stressors are known to impact mental health of asylum seekers and refugees. However, the ways in which they interact with treatment of posttraumatic stress disorder (PTSD) with these populations is still poorly understood. The aim of this study was to examine whether legal status and other resettlement stressors influence outcomes of a trauma-focused group PTSD treatment within a day-treatment setting with asylum seekers and refugees. Methods Sixty six male Iranian and Afghan patients with PTSD residing in the Netherlands were assessed with self-rated symptom checklists for PTSD, anxiety and depression, and a demographic questionnaire one week before and two weeks after the treatment. Multivariate linear regression analysis was used to examine the impact of legal status and living arrangements on the treatment outcomes per symptom domain. Results The results suggest that both asylum seekers and refugees can be helped with their mental health complaints with a trauma-focused group therapy for PTSD regardless of their legal status. Obtaining a refugee status in a course of the treatment appears to improve the treatment outcomes. Conclusions Legal status is impacting outcomes of group therapy for PTSD with male asylum seekers and refugees. Asylum seekers may benefit from group treatment regardless of unstable living conditions. PMID:23705873

  8. [FEATURES OF CONSTITUTIONAL CHARACTERISTICS OF YOUNG MALES AGED OF 17-20 YEARS, NATIVES OF THE BAIKAL REGION WITH REGARD TO THEIR FUNCTIONAL GROUPS OF HEALTH].

    PubMed

    Kolokoltsev, M M

    2016-01-01

    The study of somatotypes of the constitution is an important point in planning of the improvements of measures among the population in various regions of Russia. The purpose of the work was to reveal features of age dynamics of somatotypes of the constitution in students of youthful age of the Baikal Region by means of somatotyping according to scheme by Nikityuk B. A. and Kozlova A.I (1990) with taking into account their functional group of health. There were examined 1286 Slavic young males, natives of the Irkutsk region, aged of 17-20 years, from them, according to data of the medical examination 996 were referred to the 1st (main) and 290--to the 2nd (preparatory) functional group of health for physical exercises. There were established significant differences in somatotypes of the constitution in young men of the 1st and 2nd functional groups of health. In both functional groups there is noted a significant amount of young males with transitional somatotypes that testifies to incompleteness of growth processes of their organism. The obtained results of a somatotyping are used in the educational process for a training individualization on physical culture of students of IRGTU, and also in construction of independent physical--improving programs. PMID:27430074

  9. Multiple-Family Group Intervention for Incarcerated Male Adolescents Who Sexually Offend and Their Families: Change in Maladaptive Emotion Regulation Predicts Adaptive Change in Adolescent Behaviors.

    PubMed

    Keiley, Margaret K; Zaremba-Morgan, Ali; Datubo-Brown, Christiana; Pyle, Raven; Cox, Milira

    2015-07-01

    The multiple-family group intervention is an effective, yet affordable, 8-week treatment that is conducted in a juvenile correctional institution in Alabama with adolescents who sexually offend and their families. Data from 115 incarcerated male adolescents and their male and female caregivers collected at pre-, post-, and 1-year follow-up were used to determine that problem behaviors (internalizing, externalizing) decreased over pre- and posttest and the significant decreases in maladaptive emotion regulation predicted those changes. Adolescent-reported anxiety over abandonment and attachment dependence on parents increased significantly; these changes were predicted by decreases in maladaptive emotion regulation. Linear growth models were also fit over the 3 time points and indicate decreases in adolescent problem behavior and maladaptive emotion regulation. PMID:24809985

  10. Victimization among female and male sexual minority status groups: evidence from the British Crime Survey 2007-2010.

    PubMed

    Mahoney, Bere; Davies, Michelle; Scurlock-Evans, Laura

    2014-01-01

    International surveys of victims show crime rates in England and Wales, including hate crimes, are among the highest in Europe. Nevertheless, sexual minority status is a less considered risk factor in general victimization research. This study used sexual minority status and sex to predict victimization across British Crime Surveys from 2007-2010. Logistic regression analyses showed sexual minority status groups were more likely than heterosexuals to be victimized from any and some specific crimes. However, bisexuals rather than lesbians or gay men were more consistently victimized, notably by sexual attacks and within the household. Implications for understanding victimization among these groups are discussed. PMID:24972149

  11. Evolution and dynamics of megaplasmids with genome sizes larger than 100 kb in the Bacillus cereus group

    PubMed Central

    2013-01-01

    Background Plasmids play a crucial role in the evolution of bacterial genomes by mediating horizontal gene transfer. However, the origin and evolution of most plasmids remains unclear, especially for megaplasmids. Strains of the Bacillus cereus group contain up to 13 plasmids with genome sizes ranging from 2 kb to 600 kb, and thus can be used to study plasmid dynamics and evolution. Results This work studied the origin and evolution of 31 B. cereus group megaplasmids (>100 kb) focusing on the most conserved regions on plasmids, minireplicons. Sixty-five putative minireplicons were identified and classified to six types on the basis of proteins that are essential for replication. Twenty-nine of the 31 megaplasmids contained two or more minireplicons. Phylogenetic analysis of the protein sequences showed that different minireplicons on the same megaplasmid have different evolutionary histories. Therefore, we speculated that these megaplasmids are the results of fusion of smaller plasmids. All plasmids of a bacterial strain must be compatible. In megaplasmids of the B. cereus group, individual minireplicons of different megaplasmids in the same strain belong to different types or subtypes. Thus, the subtypes of each minireplicon they contain may determine the incompatibilities of megaplasmids. A broader analysis of all 1285 bacterial plasmids with putative known minireplicons whose complete genome sequences were available from GenBank revealed that 34% (443 plasmids) of the plasmids have two or more minireplicons. This indicates that plasmid fusion events are general among bacterial plasmids. Conclusions Megaplasmids of B. cereus group are fusion of smaller plasmids, and the fusion of plasmids likely occurs frequently in the B. cereus group and in other bacterial taxa. Plasmid fusion may be one of the major mechanisms for formation of novel megaplasmids in the evolution of bacteria. PMID:24295128

  12. Aerobic Capacity, Activity Levels and Daily Energy Expenditure in Male and Female Adolescents of the Kenyan Nandi Sub-Group

    PubMed Central

    Gibson, Alexander R.; Ojiambo, Robert; Konstabel, Kenn; Lieberman, Daniel E.; Reilly, John J.; Speakman, John R.; Pitsiladis, Yannis P.

    2013-01-01

    The relative importance of genetic and socio-cultural influences contributing to the success of east Africans in endurance athletics remains unknown in part because the pre-training phenotype of this population remains incompletely assessed. Here cardiopulmonary fitness, physical activity levels, distance travelled to school and daily energy expenditure in 15 habitually active male (13.9±1.6 years) and 15 habitually active female (13.9±1.2) adolescents from a rural Nandi primary school are assessed. Aerobic capacity () was evaluated during two maximal discontinuous incremental exercise tests; physical activity using accelerometry combined with a global positioning system; and energy expenditure using the doubly labelled water method. The of the male and female adolescents were 73.9±5.7 ml. kg−1. min−1 and 61.5±6.3 ml. kg−1. min−1, respectively. Total time spent in sedentary, light, moderate and vigorous physical activities per day was 406±63 min (50% of total monitored time), 244±56 min (30%), 75±18 min (9%) and 82±30 min (10%). Average total daily distance travelled to and from school was 7.5±3.0 km (0.8–13.4 km). Mean daily energy expenditure, activity-induced energy expenditure and physical activity level was 12.2±3.4 MJ. day−1, 5.4±3.0 MJ. day−1 and 2.2±0.6. 70.6% of the variation in was explained by sex (partial R2 = 54.7%) and body mass index (partial R2 = 15.9%). Energy expenditure and physical activity variables did not predict variation in once sex had been accounted for. The highly active and energy-demanding lifestyle of rural Kenyan adolescents may account for their exceptional aerobic fitness and collectively prime them for later training and athletic success. PMID:23805234

  13. Part II: differences between sexually victimized and nonsexually victimized male adolescent sexual abusers and delinquent youth: further group comparisons of developmental antecedents and behavioral challenges.

    PubMed

    Leibowitz, George S; Burton, David L; Howard, Alan

    2012-01-01

    In a recent paper published in the Journal of Child Sexual Abuse, we assessed the differences between sexually victimized and nonsexually victimized male adolescent sexual abusers ( Burton, Duty, & Leibowitz, 2011 ). We found that the sexually victimized group had more severe developmental antecedents (e.g., trauma and early exposure to pornography) and behavioral difficulties (sexual aggression, arousal, pornography use, and nonsexual offenses). The present study compares sexually victimized and nonsexually victimized adolescent sexual abusers with a group of nonsexually victimized delinquent youth. Findings included that delinquent youth had fewer behavioral and developmental problems than the comparison groups. In addition, sexually victimized sexual abusers had the highest mean scores on trauma and personality measures. Implications for research and treatment are offered. PMID:22574846

  14. How Male, Female, and Mixed-Gender Groups Regard Interaction and Leadership Differences in the Business Communication Course.

    ERIC Educational Resources Information Center

    Winter, Janet K.; Neal, Joan C.; Waner, Karen K.

    2001-01-01

    Offers five recommendations for teachers or facilitators of team communication: (1) students should avoid groupthink; (2) offer students methods for reaching agreement in a timely manner; (3) vary subjects of group writing assignments; (4) encourage all students to be active participants; and (5) emphasize the importance of good writing skills to…

  15. Power and sample size determination for group comparison of patient-reported outcomes using polytomous Rasch models.

    PubMed

    Hardouin, Jean-Benoit; Blanchin, Myriam; Feddag, Mohand-Larbi; Le Néel, Tanguy; Perrot, Bastien; Sébille, Véronique

    2015-07-20

    The analysis of patient-reported outcomes or other psychological traits can be realized using the Rasch measurement model. When the objective of a study is to compare groups of individuals, it is important, before the study, to define a sample size such that the group comparison test will attain a given power. The Raschpower procedure (RP) allows doing so with dichotomous items. The RP is extended to polytomous items. Several computational issues were identified, and adaptations have been proposed. The performance of this new version of RP is assessed using simulations. This adaptation of RP allows obtaining a good estimate of the expected power of a test to compare groups of patients in a large number of practical situations. A Stata module, as well as its implementation online, is proposed to perform the RP. Two versions of the RP for polytomous items are proposed (deterministic and stochastic versions). These two versions produce similar results in all of the tested cases. We recommend the use of the deterministic version, when the measure is obtained using small questionnaires or items with a few number of response categories, and the stochastic version elsewhere, so as to optimize computing time. PMID:25787270

  16. Brain abnormalities in male children and adolescents with hemophilia: detection with MR imaging. The Hemophilia Growth and Development Study Group.

    PubMed

    Wilson, D A; Nelson, M D; Fenstermacher, M J; Bohan, T P; Hopper, K D; Tilton, A; Mitchell, W G; Contant, C F; Maeder, M A; Donfield, S M

    1992-11-01

    Cranial magnetic resonance (MR) imaging was performed in 124 male patients (aged 7-19 years), from 14 institutions, in whom a diagnosis of moderate to severe hemophilia was made. Blood tests in all subjects were negative for human immunodeficiency virus. Findings in MR studies were abnormal in 25 (20.2%) subjects. Six lesions in five subjects were classified as congenital. The most commonly identified congenital lesion was a posterior fossa collection of cerebrospinal fluid (five cases). Twenty-two subjects had acquired lesions that were probably related to the hemophilia or its treatment. The most commonly acquired lesions were single- or multifocal areas of high signal intensity within the white matter on T2-weighted images noted in 14 (11.3%) subjects. Two subjects had large focal areas of brain atrophy, and six had some degree of diffuse cerebral cortical atrophy. Three subjects (2.4%) had hemorrhagic lesions. To the authors' knowledge, the unexpected finding of small, focal, nonhemorrhagic white matter lesions has not previously been reported. PMID:1410372

  17. Power and Sample Size Determination for the Group Comparison of Patient-Reported Outcomes with Rasch Family Models

    PubMed Central

    Blanchin, Myriam; Hardouin, Jean-Benoit; Guillemin, Francis; Falissard, Bruno; Sébille, Véronique

    2013-01-01

    Background Patient-reported outcomes (PRO) that comprise all self-reported measures by the patient are important as endpoint in clinical trials and epidemiological studies. Models from the Item Response Theory (IRT) are increasingly used to analyze these particular outcomes that bring into play a latent variable as these outcomes cannot be directly observed. Preliminary developments have been proposed for sample size and power determination for the comparison of PRO in cross-sectional studies comparing two groups of patients when an IRT model is intended to be used for analysis. The objective of this work was to validate these developments in a large number of situations reflecting real-life studies. Methodology The method to determine the power relies on the characteristics of the latent trait and of the questionnaire (distribution of the items), the difference between the latent variable mean in each group and the variance of this difference estimated using Cramer-Rao bound. Different scenarios were considered to evaluate the impact of the characteristics of the questionnaire and of the variance of the latent trait on performances of the Cramer-Rao method. The power obtained using Cramer-Rao method was compared to simulations. Principal Findings Powers achieved with the Cramer-Rao method were close to powers obtained from simulations when the questionnaire was suitable for the studied population. Nevertheless, we have shown an underestimation of power with the Cramer-Rao method when the questionnaire was less suitable for the population. Besides, the Cramer-Rao method stays valid whatever the values of the variance of the latent trait. Conclusions The Cramer-Rao method is adequate to determine the power of a test of group effect at design stage for two-group comparison studies including patient-reported outcomes in health sciences. At the design stage, the questionnaire used to measure the intended PRO should be carefully chosen in relation to the studied

  18. Effective porosity and pore-throat sizes of Conasauga Group mudrock: Application, test and evaluation of petrophysical techniques

    SciTech Connect

    Dorsch, J.; Katsube, T.J.; Sanford, W.E. |; Dugan, B.E.; Tourkow, L.M.

    1996-04-01

    Effective porosity (specifically referring to the interconnected pore space) was recently recognized as being essential in determining the effectiveness and extent of matrix diffusion as a transport mechanism within fractured low-permeability rock formations. The research presented in this report was performed to test the applicability of several petrophysical techniques for the determination of effective porosity of fine-grained siliciclastic rocks. In addition, the aim was to gather quantitative data on the effective porosity of Conasauga Group mudrock from the Oak Ridge Reservation (ORR). The quantitative data reported here include not only effective porosities based on diverse measurement techniques, but also data on the sizes of pore throats and their distribution, and specimen bulk and grain densities. The petrophysical techniques employed include the immersion-saturation method, mercury and helium porosimetry, and the radial diffusion-cell method.

  19. Attitudes towards ideal family size of different ethnic/nationality groups in Great Britain, France and Germany.

    PubMed

    Penn, Roger; Lambert, Paul

    2002-01-01

    This article reports upon results from a European Union funded project on the integration of children of international migrants in Britain, France and Germany. It provides both a descriptive and a multivariate analysis of the factors that determine attitudes towards ideal family size. The results reveal that there are large differences between ethnic groups in Britain: Indian and Pakistani respondents in Britain expressed a preference for significantly larger families. However, many children of international migrants expressed a desire for smaller families than the autochthonous population in both countries. This was particularly the case for Portuguese respondents in France and Turks in Germany. Religious affiliation also had a significant effect, above and beyond ethnicity per se. Both Moslems and Christians preferred larger families than those with no religious affiliation. The article concludes that ethnic differences in attitudes towards fertility behaviour will remain important in the foreseeable future in western Europe, particularly in Britain. PMID:12138614

  20. Third parties, violence, and conflict resolution: the role of group size and collective action in the microregulation of violence.

    PubMed

    Levine, Mark; Taylor, Paul J; Best, Rachel

    2011-03-01

    Although researchers know much about the causes of aggression, they know surprisingly little about how aggression leads to violence or how violence is controlled. To explore the microregulation of violence, we conducted a systematic behavioral analysis of footage from closed-circuit television surveillance of public spaces. Using 42 incidents involving 312 people, we compared aggressive incidents that ended in violence with those that did not. Behaviors of antagonists and third parties were coded as either escalating or conciliatory acts. Results showed that third parties were more likely to take conciliatory actions than to escalate violence and that this tendency increased as group size increased. This analysis revealed a pattern of third-party behaviors that prevent aggression from becoming violent and showed that conciliatory behaviors are more successful when carried out by multiple third parties than when carried out by one person. We conclude by emphasizing the importance of collective third-party dynamics in understanding conflict resolution. PMID:21303991

  1. Standard energy metabolism of a desert harvester ant, Pogonomyrmex rugosus: Effects of temperature, body mass, group size, and humidity

    SciTech Connect

    Lighton, J.R.B.; Bartholomew, G.A. )

    1988-07-01

    Pogonomyrmex rugosus is an important seed predator in the Mojave Desert of the southwestern United States. Its standard rate of O{sub 2} consumption (Vo{sub 2}) varied significantly with temperature. The ratio of the Vo{sub 2} values at 10{degree}C increments in body temperature, Q{sub 10}, also varied with temperature; methods of calculating Vo{sub 2} from temperature with a shifting Q{sub 10} are described. Vo{sub 2} also varied with body mass. Vo{sub 2} was inversely related to relative humidity and was independent of group size. The rise in Vo{sub 2} at low relative humidities was caused by increased activity and resulted in higher rates of net water loss. The primary metabolic adaptation to xeric conditions in P. rugosus appears to be a lower-than-predicted metabolic rate.

  2. Analyzing indirect effects in cluster randomized trials. The effect of estimation method, number of groups and group sizes on accuracy and power

    PubMed Central

    Hox, Joop J.; Moerbeek, Mirjam; Kluytmans, Anouck; van de Schoot, Rens

    2013-01-01

    Cluster randomized trials assess the effect of an intervention that is carried out at the group or cluster level. Ajzen's theory of planned behavior is often used to model the effect of the intervention as an indirect effect mediated in turn by attitude, norms and behavioral intention. Structural equation modeling (SEM) is the technique of choice to estimate indirect effects and their significance. However, this is a large sample technique, and its application in a cluster randomized trial assumes a relatively large number of clusters. In practice, the number of clusters in these studies tends to be relatively small, e.g., much less than fifty. This study uses simulation methods to find the lowest number of clusters needed when multilevel SEM is used to estimate the indirect effect. Maximum likelihood estimation is compared to Bayesian analysis, with the central quality criteria being accuracy of the point estimate and the confidence interval. We also investigate the power of the test for the indirect effect. We conclude that Bayes estimation works well with much smaller cluster level sample sizes such as 20 cases than maximum likelihood estimation; although the bias is larger the coverage is much better. When only 5–10 clusters are available per treatment condition even with Bayesian estimation problems occur. PMID:24550881

  3. Analyzing indirect effects in cluster randomized trials. The effect of estimation method, number of groups and group sizes on accuracy and power.

    PubMed

    Hox, Joop J; Moerbeek, Mirjam; Kluytmans, Anouck; van de Schoot, Rens

    2014-01-01

    Cluster randomized trials assess the effect of an intervention that is carried out at the group or cluster level. Ajzen's theory of planned behavior is often used to model the effect of the intervention as an indirect effect mediated in turn by attitude, norms and behavioral intention. Structural equation modeling (SEM) is the technique of choice to estimate indirect effects and their significance. However, this is a large sample technique, and its application in a cluster randomized trial assumes a relatively large number of clusters. In practice, the number of clusters in these studies tends to be relatively small, e.g., much less than fifty. This study uses simulation methods to find the lowest number of clusters needed when multilevel SEM is used to estimate the indirect effect. Maximum likelihood estimation is compared to Bayesian analysis, with the central quality criteria being accuracy of the point estimate and the confidence interval. We also investigate the power of the test for the indirect effect. We conclude that Bayes estimation works well with much smaller cluster level sample sizes such as 20 cases than maximum likelihood estimation; although the bias is larger the coverage is much better. When only 5-10 clusters are available per treatment condition even with Bayesian estimation problems occur. PMID:24550881

  4. Population Balance Modeling of Polydispersed Bubbly Flow in Continuous-Casting Using Multiple-Size-Group Approach

    NASA Astrophysics Data System (ADS)

    Liu, Zhongqiu; Li, Linmin; Qi, Fengsheng; Li, Baokuan; Jiang, Maofa; Tsukihashi, Fumitaka

    2015-02-01

    A population balance model based on the multiple-size-group (MUSIG) approach has been developed to investigate the polydispersed bubbly flow inside the slab continuous-casting mold and bubble behavior including volume fraction, breakup, coalescence, and size distribution. The Eulerian-Eulerian approach is used to describe the equations of motion of the two-phase flow. All the non-drag forces (lift force, virtual mass force, wall lubrication force, and turbulent dispersion force) and drag force are incorporated in this model. Sato and Sekiguchi model is used to account for the bubble-induced turbulence. Luo and Svendsen model and Prince and Blanch model are used to describe the bubbles breakup and coalescence behavior, respectively. A 1/4th water model of the slab continuous-casting mold was applied to investigate the distribution and size of bubbles by injecting air through a circumferential inlet chamber which was made of the specially-coated samples of mullite porous brick, which is used for the actual upper nozzle. Against experimental data, numerical results showed good agreement for the gas volume fraction and local bubble Sauter mean diameter. The bubble Sauter mean diameter in the upper recirculation zone decreases with increasing water flow rate and increases with increasing gas flow rate. The distribution of bubble Sauter mean diameter along the width direction of the upper mold increases first, and then gradually decreases from the SEN to the narrow wall. Close agreements between the predictions and measurements demonstrate the capability of the MUSIG model in modeling bubbly flow inside the continuous-casting mold.

  5. Spectrum and Inoculum Size Effect of a Rapid Antigen Detection Test for Group A Streptococcus in Children with Pharyngitis

    PubMed Central

    Cohen, Jérémie F.; Chalumeau, Martin; Levy, Corinne; Bidet, Philippe; Thollot, Franck; Wollner, Alain; Bingen, Edouard; Cohen, Robert

    2012-01-01

    Background The stability of the accuracy of a diagnostic test is critical to whether clinicians can rely on its result. We aimed to assess whether the performance of a rapid antigen detection test (RADT) for group A streptococcus (GAS) is affected by the clinical spectrum and/or bacterial inoculum size. Methods Throat swabs were collected from 785 children with pharyngitis in an office-based, prospective, multicenter study (2009–2010). We analysed the effect of clinical spectrum (i.e., the McIsaac score and its components) and inoculum size (light or heavy GAS growth) on the accuracy (sensitivity, specificity, likelihood ratios and predictive values) of a RADT, with laboratory throat culture as the reference test. We also evaluated the accuracy of a McIsaac-score–based decision rule. Results GAS prevalence was 36% (95CI: 33%–40%). The inoculum was heavy for 85% of cases (81%–89%). We found a significant spectrum effect on sensitivity, specificity, likelihood ratios and positive predictive value (p<0.05) but not negative predictive value, which was stable at about 92%. RADT sensitivity was greater for children with heavy than light inoculum (95% vs. 40%, p<0.001). After stratification by inoculum size, the spectrum effect on RADT sensitivity was significant only in patients with light inoculum, on univariate and multivariate analysis. The McIsaac-score–based decision rule had 99% (97%–100%) sensitivity and 52% (48%–57%) specificity. Conclusions Variations in RADT sensitivity only occur in patients with light inocula. Because the spectrum effect does not affect the negative predictive value of the test, clinicians who want to rule out GAS can rely on negative RADT results regardless of clinical features if they accept that about 10% of children with negative RADT results will have a positive throat culture. However, such a policy is more acceptable in populations with very low incidence of complications of GAS infection. PMID:22768060

  6. Population Balance Modeling of Polydispersed Bubbly Flow in Continuous-Casting Using Multiple-Size-Group Approach

    NASA Astrophysics Data System (ADS)

    Liu, Zhongqiu; Li, Linmin; Qi, Fengsheng; Li, Baokuan; Jiang, Maofa; Tsukihashi, Fumitaka

    2014-09-01

    A population balance model based on the multiple-size-group (MUSIG) approach has been developed to investigate the polydispersed bubbly flow inside the slab continuous-casting mold and bubble behavior including volume fraction, breakup, coalescence, and size distribution. The Eulerian-Eulerian approach is used to describe the equations of motion of the two-phase flow. All the non-drag forces (lift force, virtual mass force, wall lubrication force, and turbulent dispersion force) and drag force are incorporated in this model. Sato and Sekiguchi model is used to account for the bubble-induced turbulence. Luo and Svendsen model and Prince and Blanch model are used to describe the bubbles breakup and coalescence behavior, respectively. A 1/4th water model of the slab continuous-casting mold was applied to investigate the distribution and size of bubbles by injecting air through a circumferential inlet chamber which was made of the specially-coated samples of mullite porous brick, which is used for the actual upper nozzle. Against experimental data, numerical results showed good agreement for the gas volume fraction and local bubble Sauter mean diameter. The bubble Sauter mean diameter in the upper recirculation zone decreases with increasing water flow rate and increases with increasing gas flow rate. The distribution of bubble Sauter mean diameter along the width direction of the upper mold increases first, and then gradually decreases from the SEN to the narrow wall. Close agreements between the predictions and measurements demonstrate the capability of the MUSIG model in modeling bubbly flow inside the continuous-casting mold.

  7. Group size of veal calves does not affect production, physiological, or hematological indicators of welfare and has transient effects on health

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Holstein-Friesian bull calves (n = 168; 44 ± 3 d of age), were used to investigate the effect of group size on performance, health, hematology, and welfare of veal calves. Groups of calves were assigned to 1 of 3 group housing treatments with 2, 4, or 8 calves per pen (initial BW 65.3 ± 3.7, 66.5 ± ...

  8. Gross and microscopic visceral anatomy of the male Cape fur seal, Arctocephalus pusillus pusillus (Pinnipedia: Otariidae), with reference to organ size and growth

    PubMed Central

    STEWARDSON, CAROLYN L.; HEMSLEY, SUSAN; MEYER, MIKE A.; CANFIELD, PAUL J.; MAINDONALD, JOHN H.

    1999-01-01

    The gross and microscopic anatomy of the Cape fur seal heart, lung, liver, spleen, stomach, intestine and kidneys (n = 31 seals) is described. Absolute and relative size of organs from 30 male seals are presented, with histological examination conducted on 7 animals. The relationship between log body weight, log organ weight and age was investigated using linear regression. Twenty five animals were of known age, while 6 were aged from counts of incremental lines observed in the dentine of tooth sections. For the range of ages represented in this study, body weight changes were accurately described by the exponential growth equation, weight = wort, with body weight increasing by 23% per annum until at least 9–10 y of age. Organ weight increased at a rate of between 25% and 33% per annum until at least 9–10 y of age, with the exception of the intestines, where exponential increase appeared to have ceased by about 7 y. The relationship between body weight and organ weight was investigated using logarithmic transformations of the allometric equation, y = axb, where the exponent b is 1 if organ weight is proportional to body weight. Most organs increased in proportion to the body. However, the heart, liver and spleen had exponents b > 1, suggesting that these organs increased at a faster rate than the body. The basic anatomical features of the viscera were similar to those of other pinnipeds, with some exceptions, including the arrangement of the multilobed lung and liver. Apart from the large liver and kidneys, relative size of the organs did not differ greatly from similar sized terrestrial carnivores. The histological features of the organs were generally consistent with those previously described for this species and other otariids. The heart, as in other pinnipeds, was unlike that of cetacea in not having unusually thick endocardium or prominent Purkinje cells. Notable histological features of the lungs included prominent fibrous septa, prominent smooth muscle

  9. The Economic and Epidemiological Impact of Focusing Voluntary Medical Male Circumcision for HIV Prevention on Specific Age Groups and Regions in Tanzania

    PubMed Central

    2016-01-01

    Background Since its launch in 2010, the Tanzania National Voluntary Medical Male Circumcision (VMMC) Program has focused efforts on males ages 10–34 in 11 priority regions. Implementers have noted that over 70% of VMMC clients are between the ages of 10 and 19, raising questions about whether additional efforts would be required to recruit men age 20 and above. This analysis uses mathematical modeling to examine the economic and epidemiological consequences of scaling up VMMC among specific age groups and priority regions in Tanzania. Methods and Findings Analyses were conducted using the Decision Makers’ Program Planning Tool Version 2.0 (DMPPT 2.0), a compartmental model implemented in Microsoft Excel 2010. The model was populated with population, mortality, and HIV incidence and prevalence projections from external sources, including outputs from Spectrum/AIDS Impact Module (AIM). A separate DMPPT 2.0 model was created for each of the 11 priority regions. Tanzania can achieve the most immediate impact on HIV incidence by circumcising males ages 20–34. This strategy would also require the fewest VMMCs for each HIV infection averted. Circumcising men ages 10–24 will have the greatest impact on HIV incidence over a 15-year period. The most cost-effective approach (lowest cost per HIV infection averted) targets men ages 15–34. The model shows the VMMC program is cost saving in all 11 priority regions. VMMC program cost-effectiveness varies across regions due to differences in projected HIV incidence, with the most cost-effective programs in Njombe and Iringa. Conclusions The DMPPT 2.0 results reinforce Tanzania’s current VMMC strategy, providing newfound confidence in investing in circumcising adolescents. Tanzanian policy makers and program implementers will continue to focus scale-up of VMMC on men ages 10–34 years, seeking to maximize program impact and cost-effectiveness while acknowledging trends in demand among the younger and older age groups

  10. Colony social stress differentially alters blood pressure and resistance-sized mesenteric artery reactivity in SHR/y and WKY male rats.

    PubMed

    Toot, Jonathan D; Reho, John J; Novak, Jacqueline; Dunphy, Gail; Ely, Daniel L; Ramirez, Rolando J

    2011-01-01

    Increased sympathetic nervous system (SNS) activity, testosterone, and spontaneously hypertensive rat Y chromosome (SHR Yc) play a role in a genetic model of hypertension. Male rats with the SHR Yc and Wistar-Kyoto (WKY) autosomes (denoted SHR/y) exhibit these characteristics when compared to rats with the WKY Yc and WKY autosomes (denoted WKY). We hypothesized that chronic social stress will increase blood pressure and SNS activity more in SHR/y males compared to WKY males, resulting in increased myogenic reactivity along with decreased vasoconstriction of small mesenteric arteries. SHR/y and WKY males were housed in strain- specific colonies (10 males with 10 females) or as controls (10 males). Systolic blood pressure (SBP) and blood samples were collected prior to termination. Second-order mesenteric arteries were studied using a pressure arteriograph in which myogenic reactivity and phenylephrine (PE) responsiveness were measured. SHR/y colony SBP, and circulating norepinephrine and testosterone concentrations were elevated compared to control and WKY colony males (p < 0.05). Mesenteric artery myogenic reactivity was increased in SHR/y colony males (p < 0.001). Mesenteric arteries from SHR/y colony males exhibited a significant decrease in PE-induced constriction. Colony social stress elevated both SNS activity and testosterone level which may be responsible for the increased mesenteric artery myogenic reactivity, and SBP as noted in SHR/y males. PMID:20666653

  11. Study of a European male champion in 10-km road races in the age group >85 years.

    PubMed

    Knechtle, Beat; Kohler, Götz; Rosemann, Thomas

    2010-07-01

    An 86-year-old man became a double champion in the European championship for road running in 2009. He won the 10-km road run with a time of 58:01 minutes, setting a new European record for men aged 85 and older. Two days later, he became a European champion in the same age group for the half-marathon, with a time of 2:17 hours. He started his running career at the age of 64 years and has trained for about an hour three times a week every year since. During these 22 years, he has performed several road runs each year, ranging from 2.5 to 10 km, and also completed a number of half-marathons. Although his running speeds had progressively slowed since the age of 64, there was an increased rate of decline at the age of 82. This man's outstanding performance should encourage other master runners to continue running and competing past the age of 85. PMID:20671823

  12. Reproductive success in wild and hatchery male coho salmon

    PubMed Central

    Neff, Bryan D.; Garner, Shawn R.; Fleming, Ian A.; Gross, Mart R.

    2015-01-01

    Salmon produced by hatcheries have lower fitness in the wild than naturally produced salmon, but the factors underlying this difference remain an active area of research. We used genetic parentage analysis of alevins produced by experimentally mixed groups of wild and hatchery coho salmon (Oncorhynchus kisutch) to quantify male paternity in spawning hierarchies. We identify factors influencing paternity and revise previously published behavioural estimates of reproductive success for wild and hatchery males. We observed a strong effect of hierarchy size and hierarchy position on paternity: in two-male hierarchies, the first male sired 63% (±29%; s.d.) of the alevins and the second male 37% (±29%); in three-male hierarchies, the first male sired 64% (±26%), the second male 24% (±20%) and the third male 12% (±10%). As previously documented, hatchery males hold inferior positions in spawning hierarchies, but we also discovered that hatchery males had only 55–84% the paternity of wild males when occupying the same position within a spawning hierarchy. This paternity difference may result from inferior performance of hatchery males during sperm competition, female mate choice for wild males, or differential offspring survival. Regardless of its cause, the combination of inferior hierarchical position and inferior success at a position resulted in hatchery males having only half (51%) the reproductive success of wild males. PMID:26361548

  13. Differential response of male and female Diabrotica speciosa (coleoptera: chrysomelidae) to bitter cucurbit-based toxic baits in relation to the treated area size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbitacins are fed on by male and female Luperini but field trials reveal that males are far more attracted to them than females. The sex ratio and number of beetles killed by an application of cucurbitacin based toxic baits was assessed at two different scales: small areas of 100 m2, and a large...

  14. Specialist group therapy for psychological factors associated with firesetting: Evidence of a treatment effect from a non-randomized trial with male prisoners.

    PubMed

    Gannon, Theresa A; Alleyne, Emma; Butler, Helen; Danby, Harriet; Kapoor, Aparna; Lovell, Tamsin; Mozova, Katarina; Spruin, Elizabeth; Tostevin, Tracey; Tyler, Nichola; Ciardha, Caoilte Ó

    2015-10-01

    Despite huge societal costs associated with firesetting, no standardized therapy has been developed to address this hugely damaging behavior. This study reports the evaluation of the first standardized CBT group designed specifically to target deliberate firesetting in male prisoners (the Firesetting Intervention Programme for Prisoners; FIPP). Fifty-four male prisoners who had set a deliberate fire were referred for FIPP treatment by their prison establishment and psychologically assessed at baseline, immediately post treatment, and three-months post treatment. Prisoners who were treatment eligible yet resided at prison establishments not identified for FIPP treatment were recruited as Treatment as Usual controls and tested at equivalent time-points. Results showed that FIPP participants improved on one of three primary outcomes (i.e., problematic fire interest and associations with fire), and made some improvement on secondary outcomes (i.e., attitudes towards violence and antisocial attitudes) post treatment relative to controls. Most notable gains were made on the primary outcome of fire interest and associations with fire and individuals who gained in this area tended to self-report more serious firesetting behavior. FIPP participants maintained all key improvements at three-month follow up. These outcomes suggest that specialist CBT should be targeted at those holding the most serious firesetting history. PMID:26248329

  15. The effects of rearing density on growth, size heterogeneity and inter-individual variation of feed intake in monosex male Nile tilapia Oreochromis niloticus L.

    PubMed

    Azaza, M S; Assad, A; Maghrbi, W; El-Cafsi, M

    2013-11-01

    The growth dispersion of farmed fish is a subject of increasing interest and one of the most important factors in stocking density. On a duration of 60 days, the effect of stocking density on the growth, coefficient of variation and inter-individual variation of feed intake (CVFI) of juvenile Nile tilapia Oreochromis niloticus L. (14.9 ± 1.2 g) were studied in an experimental tank-based flow-through system. Groups of fish were stocked at four stocking densities: 200, 400, 600 and 800 fish/m3, corresponding to a density of ∼3, 6, 9 and 12 kg/m3 and referred to as D1, D2, D3 and D4, respectively. Each treatment was applied to triplicate groups in a completely randomized design. No treatment-related mortality was observed. The fish densities increased throughout the experiment from 3 to 23.5, 6 to 43.6, 9 to 56.6 and 12 to 69 kg/m3. Results show that mass gain and specific growth rate (SGR, %M/day) were negatively correlated with increased stocking density. Groups of the D1 treatment reached a mean final body mass (FBM) of 119.3 g v. 88.9 g for the D4 groups. Feed conversion ratios (FCRs) were 1.38, 1.54, 1.62 and 1.91 at D1, D2, D3 and D4 treatments, respectively. Growth heterogeneity, expressed by the inter-individual variations of fish mass (CVM), was significantly affected by time (P < 0.001), stocking density (P < 0.001) and their interaction (P < 0.05). The difference in CVM was particularly conspicuous towards the end of the experiment and was positively correlated with stocking density. Similarly, radiographic study shows that CVFI was also found to be significantly greater for groups reared at high stocking densities (D3 and D4) than the other treatments (D1 and D2). These differences in both CVM and CVFI related to the stocking density need to be taken into account by husbandry practices to assure the production of more homogeneous fish size. A simple economic analysis indicates a parabolic relationship between profit and density with optimal final

  16. Extended male growth in a fossil hominin species.

    PubMed

    Lockwood, Charles A; Menter, Colin G; Moggi-Cecchi, Jacopo; Keyser, Andre W

    2007-11-30

    In primates that are highly sexually dimorphic, males often reach maturity later than females, and young adult males do not show the size, morphology, and coloration of mature males. Here we describe extended male development in a hominin species, Paranthropus robustus. Ranking a large sample of facial remains on the basis of dental wear stages reveals a difference in size and robusticity between young adult and old adult males. Combined with estimates of sexual dimorphism, this pattern suggests that male reproductive strategy focused on monopolizing groups of females, in a manner similar to that of silverback gorillas. However, males appear to have borne a substantial cost in the form of high rates of predation. PMID:18048687

  17. 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. PMID:18410290

  18. Attitude Differences and Task Performance for Black and White Recruits in Problem-Solving Groups of Differing Size and Racial Composition. Technical Report 75-1.

    ERIC Educational Resources Information Center

    Ruhe, John A.; Allen, William R.

    In this field study, black and white naval recruits and squad leaders in groups of varying size and racial composition performed two problem-solving tasks (knot-tying and ship-routing). Black and white leaders, subordinates and group composition (25% black tetrads, 75% black tetrads, racially balanced dyads and tetrads) were compared in measures…

  19. Multiple Size Group Modeling of Polydispersed Bubbly Flow in the Mold: An Analysis of Turbulence and Interfacial Force Models

    NASA Astrophysics Data System (ADS)

    Liu, Zhongqiu; Qi, Fengsheng; Li, Baokuan; Jiang, Maofa

    2015-04-01

    An inhomogeneous Multiple Size Group (MUSIG) model based on the Eulerian-Eulerian approach has been developed to describe the polydispersed bubbly flow inside the continuous-casting mold. A laboratory scale mold has been simulated using four different turbulence closure models (modified k - ɛ, RNG k - ɛ, k - ω, and SST) with the purpose of critically comparing their predictions of bubble Sauter mean diameter distribution with previous experimental data. Furthermore, the influences of all the interfacial momentum transfer terms including drag force, lift force, virtual mass force, wall lubrication force, and turbulent dispersion force are investigated. The breakup and coalescence effects of the bubbles are modeled according to the bubble breakup by the impact of turbulent eddies while for bubble coalescence by the random collisions driven by turbulence and wake entrainment. It has been found that the modified k - ɛ model shows better agreement than other models in predicting the bubble Sauter mean diameter profiles. Further, simulations have also been performed to understand the sensitivity of different interfacial forces. The appropriate drag force coefficient, lift force coefficient, virtual mass force coefficient, and turbulent dispersion force coefficient are chosen in accordance with measurements of water model experiments. However, the wall lubrication force does not have much effect on the current polydispersed bubbly flow system. Finally, the MUSIG model is then used to estimate the argon bubble diameter in the molten steel of the mold. The argon bubble Sauter mean diameter generated in molten steel is predicted to be larger than air bubbles in water for the similar conditions.

  20. Effective sizes for subdivided populations

    SciTech Connect

    Chesser, R.K. Univ. of Georgia, Athens, GA ); Rhodes, O.E. Jr.; Sugg, D.W.; Schnabel, A. )

    1993-12-01

    Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective size, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal rates.

  1. Approximate Sample Size Formulas for Testing Group Mean Differences when Variances Are Unequal in One-Way ANOVA

    ERIC Educational Resources Information Center

    Guo, Jiin-Huarng; Luh, Wei-Ming

    2008-01-01

    This study proposes an approach for determining appropriate sample size for Welch's F test when unequal variances are expected. Given a certain maximum deviation in population means and using the quantile of F and t distributions, there is no need to specify a noncentrality parameter and it is easy to estimate the approximate sample size needed…

  2. Male clients of brothel prostitutes as a bridge for HIV infection between high risk and low risk groups of women in Senegal

    PubMed Central

    d Gomes; Etheredge, G

    2005-01-01

    Objective: To explore the extent to which male clients of prostitutes have a role as a bridge in the spread of HIV into the general population of Dakar, Senegal. Methods: A sexual behaviour HIV prevalence survey was carried out among clients of female prostitutes working in brothels recruited outside the prostitutes' rooms after the encounter. All men entering the house and leaving the women's rooms were asked to answer the questions and to donate saliva for HIV-1 and HIV-2 testing. Results: Findings suggest that a proportion of clients form a potential bridge for HIV transmission between prostitutes and partners from the general population. They have unprotected sexual contacts with both brothel prostitutes, and steady and casual partners, and expose both unmarried and married women to HIV infection. Findings also indicate that wives are more exposed to HIV than other categories of women in the population. Conclusions: Clients of brothels' prostitutes have a significant potential for spreading HIV beyond the initial high risk behaviour groups in Senegal. Efforts should be provided to target specific groups at higher risk for HIV infection, such as young men from the densely populated working class neighbourhoods of Dakar, and women outside the commercial sex networks for HIV education and prevention. PMID:16061544

  3. Evolved psychology in a novel environment : Male macaques and the "seniority rule".

    PubMed

    Manson, J H

    1998-06-01

    The human "environment of evolutionary adaptedness" can only be inferred indirectly. In contrast, the behavior of some nonhuman animals can be compared among "natural" and various altered environments. As an example, male immigration tactics in unprovisioned versus provisioned macaque (Macaca) populations are compared using Tooby and Cosmides's (1992) framework for evolutionary functional analysis. In unprovisioned populations, social groups contain few males, and immigrant male takeovers of alpha rank occur frequently. In provisioned populations, groups contain many males, and males almost invariably enter social groups at very low rank and rise in rank only as more dominant males emigrate or die. Male conformity to the "seniority rule" is hypothesized to represent the behavioral output of an evolved decision-making algorithm (psychological mechanism) that takes into account (1) the net payoff of each rank in the dominance hierarchy and (2) the power of male group size as a predictor of the likelihood of successful immigrant takeover. PMID:26197442

  4. Population sizes and group characteristics of Siberian Crane (Leuco-geranus leucogeranus) and Hooded Crane (Grus monacha) in Poyang Lake Wetland.

    PubMed

    Shao, Ming-Qin; Guo, Hong; Jiang, Jian-Hong

    2014-09-01

    Both the Siberian Crane (Leucogeranus leucogeranus) and Hooded Crane (Grus monacha) have limited population sizes and are considered endangered by domestic Chinese and international agencies. To document the current size of their respective populations and characterize their groups, between October 2012 and April 2013 we undertook fieldwork at four nature reserve areas within the Poyang Lake wetlands. We divided Poyanghu National Nature Reserve (PYH) into the Wucheng (PWC) and Hengfeng areas (PHF), because each are each located in different counties. Our fieldwork showed that the Siberian Crane occurred mainly in PYH (364 in the PHF, 158 in the PWC) and the Nanjishan Wetland National Nature Reserve (NJS, with 200 individuals). The Hooded Crane was mainly distributed in PYH (302 in the PHF and 154 in the PWC). Family groups accounted for more than 50% of the total number of groups among both species, with Hooded Cranes forming more family groups than Siberian Cranes. Typically, these groups were formed of two adults with one offspring (Siberian Crane), and two adults with two offspring (Hooded Crane), with the mean family group size of the Siberian Crane and Hooded Crane being respectively 2.65 ± 0.53 (n=43) and 3.09 ± 0.86 (n=47) individuals per group. The mean collective group size of the Siberian Crane and Hooded Crane included 28.09 ± 24.94 (n=23) and 28.94 ± 27.97 (n=16) individuals per group, respectively, with the proportion of juveniles among Hooded Cranes being more than double that seen among the Siberian Cranes. PMID:25297076

  5. Highly competitive reindeer males control female behavior during the rut.

    PubMed

    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

  6. 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. PMID:24849073

  7. 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

  8. Teasing out the effects of macro-conditions on race-specific male homicide rates: Do distinct predictors vary by racial group and over time?

    PubMed

    Stansfield, Richard; Parker, Karen F

    2013-05-01

    Researchers tend to capture the multiple disadvantages facing urban areas by using an all-encompassing disadvantage index, which combines poverty, joblessness and other economic predictors into a single index. While the use of this index is important for conceptual and methodological reasons, questions remain about whether these city characteristics differ in magnitude and significance when influencing race-specific homicide rates and whether or not there effects exhibit stability or vary over time? This article examines how discrete measures of disadvantage differ in their importance for race-specific groups over three critical time points: 1980, 1990, and 2000. After accounting for problems associated with statistical inferences, cross sectional, Seemingly Unrelated Regression (SUR) analyses reveal that family disruption and poverty status were among the strongest predictors of race-specific homicide rates. Wald tests for the equality of coefficients confirmed significant differences in the influence of many discrete measures of disadvantage for white and black males, but the number of differences declined from 1980 and into the 2000s. That is, along with the crime drop, our research reveals increasing racial parity in structural predictors over time. PMID:23521985

  9. Sample Size and Power for a Logrank Test and Cox Proportional Hazards Model with Multiple Groups and Strata, or a Quantitative Covariate with Multiple Strata

    PubMed Central

    Lachin, John M.

    2013-01-01

    Summary General expressions are described for the evaluation of sample size and power for the K group Mantel-logrank test or the Cox PH model score test. Under an exponential model, the method of Lachin and Foulkes [1] for the 2 group case is extended to the K ≥ 2 group case using the non-centrality parameter of the K – 1 df chi-square test. Similar results are also shown to apply to the K group score test in a Cox PH model. Lachin and Foulkes [1] employed a truncated exponential distribution to provide for a non-linear rate of enrollment. Expressions for the mean time of enrollment and the expected follow-up time in the presence of exponential losses-to-follow-up are presented. When used with the expression for the non-centrality parameter for the test, equations are derived for the evaluation of sample size and power under specific designs with R years of recruitment and T years total duration. Sample size and power are also described for a stratified-adjusted K group test and for the assessment of a group by stratum interaction. Similarly computations are described for a stratified-adjusted analysis of a quantitative covariate and a test of a stratum by covariate interaction in the Cox PH model. PMID:23670965

  10. Experiments on the Provision of Public Goods. I. Resources, Interest, Group Size, and the Free-Rider Problem.

    ERIC Educational Resources Information Center

    Marwell, Gerald; Ames, Ruth E.

    1979-01-01

    Describes study in which high school students were confronted with an investment opportunity and had to decide whether to invest in a private good which returned profits to the individual or a public good which returned profits to the group. Results indicate that "free riders" in the public good group do not contribute to the deterioration of the…

  11. Ferocious Fighting between Male Grasshoppers

    PubMed Central

    Umbers, Kate D. L.; Tatarnic, Nikolai J.; Holwell, Gregory I.; Herberstein, Marie E.

    2012-01-01

    Contests among individuals over mating opportunities are common across diverse taxa, yet physical conflict is relatively rare. Due to the potentially fatal consequences of physical fighting, most animals employ mechanisms of conflict resolution involving signalling and ritualistic assessment. Here we provide the first evidence of ubiquitous escalated fighting in grasshoppers. The chameleon grasshopper (Kosciuscola tristis) is an Australian alpine specialist, in which males engage in highly aggressive combat over ovipositing females. We describe discrete agonistic behaviours including mandible flaring, mounting, grappling, kicking and biting, and their use depending on the individual’s role as challenger or defender. We show that male role predicts damage, with challengers being more heavily damaged than males defending females (defenders). Challengers also possess wider mandibles than defenders, but are similar in other metrics of body size. Our data suggest that fights escalate between males matched in body size and that mandibles are used as weapons in this species. This system represents an exciting opportunity for future research into the evolution of costly fighting behaviour in an otherwise placid group. PMID:23166725

  12. From Planning to Implementation: An Examination of Changes in the Research Design, Sample Size, and Precision of Group Randomized Trials Launched by the Institute of Education Sciences

    ERIC Educational Resources Information Center

    Spybrook, Jessaca; Puente, Anne Cullen; Lininger, Monica

    2013-01-01

    This article examines changes in the research design, sample size, and precision between the planning phase and implementation phase of group randomized trials (GRTs) funded by the Institute of Education Sciences. Thirty-eight GRTs funded between 2002 and 2006 were examined. Three studies revealed changes in the experimental design. Ten studies…

  13. 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

  14. Maternal corticosterone deposition in avian yolk: Influence of laying order and group size in a joint-nesting, cooperatively breeding species.

    PubMed

    Schmaltz, Gregory; Quinn, James S; Schoech, Stephan J

    2016-06-01

    Glucocorticoid hormones play a key role in day-to-day adjustments to fluctuating metabolic needs. These hormones also mediate physiological and behavioral responses to stressful events, allowing individuals to cope with stressors. Various environmental insults, such as a food shortages, predation attempts, and agonistic encounters often elevate plasma glucocorticoid levels in vertebrates. Because exposure to maternally-derived (via circulation or egg) glucocorticoids may be detrimental to the developing embryo, maternal stress can have negative carryover effects on offspring fitness. We examined corticosterone, the primary avian glucocorticoid, concentrations in egg yolk in a plural-breeding, joint-nesting species, the smooth-billed ani (Crotophaga ani), in which females compete among themselves to lay eggs in the final incubated clutch. We investigated whether yolk corticosterone levels varied with laying order and group size. Because egg-laying competition leads to physiological and social stress that is intensified with group size and laying order, we predicted that yolk corticosterone levels should increase from the early to the late egg-laying period and from single female to multi-female groups. In this two-year field study, we found that yolk corticosterone levels of late-laid eggs within the communal clutch were higher in multi-female groups than in single female groups. Results from this study suggest that laying females experience higher levels of stress in multi-female groups and that this maternal stress influences yolk corticosterone concentrations. This study identifies a novel cost of group-living in plural-breeding cooperatively breeding birds, namely an increase in yolk corticosterone levels with group size that may result in detrimental effects on offspring development. PMID:27118704

  15. Primate Socioecology: New Insights from Males

    NASA Astrophysics Data System (ADS)

    Kappeler, Peter M.

    Primate males have only recently returned to the center stage of socioecological research. This review surveys new studies that examine variation in the behavior of adult males and their role in social evolution. It is shown that group size, composition, and social behavior are determined not only by resource distribution, predation risk, and other ecological factors, but that life history traits and social factors, especially those related to sexual coercion, can have equally profound consequences for social systems. This general point is illustrated by examining male behavior at three levels: the evolution of permanent associations between males and females, the causes and consequences of variation in the number of males between group-living species, and the determinants of social relationships within and between the sexes. Direct and indirect evidence reviewed in connection with all three questions indicates that the risk of infanticide has been a pervasive force in primate social evolution. Several areas are identified for future research on male life histories that should contribute to a better understanding of male reproductive strategies and corresponding female counterstrategies.

  16. Effective sizes for subdivided populations.

    PubMed

    Chesser, R K; Rhodes, O E; Sugg, D W; Schnabel, A

    1993-12-01

    Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional, single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective sizes, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal

  17. Effects of aggressive behaviour and group size on collective escape in an emergency: a test between a social identity model and deindividuation theory.

    PubMed

    Kugihara, N

    2001-12-01

    This study models escape behaviour in emergency situations and compares the ability of deindividuation and social identity-based explanations in particular to account for responses. According to deindividuation theory, the larger the group, the higher the degree of anonymity and the stronger antisocial responses such as competitiveness will be. Moreover, the competition for escape should be more severe, and the escape rate lowered, in a large group, regardless of whether participants have an aggressive option. A social identity model predicts that when group members have an option of aggressive behaviour, the salience of the aggressive norm in a larger group will be stronger than that in a smaller group. In contrast, when participants only have concessive option, the salience of the non-aggressive norm in a large group is expected to be stronger than that in a small group. The results of Study 1 supported the social identity model. Study 2 tested how participants responded to their norm. The social identity model suggests a more conscious and socially regulated process whereas deindividuation theory implies an unconscious or unregulated process. The results showed that what directly affects norm formation is the density of stimulus, that is, the amount of aggression received from others and of others' escape activity divided by group size. The results suggest the conscious process of the norm formation and support the social identity model. PMID:11795069

  18. Psychological differences between influence of temperament with the hemishere asymmetry of a brain on size of sensorymotor reactions of male and female cosmonauts

    NASA Astrophysics Data System (ADS)

    Prisniakova, Lyudmila; Prisniakov, Volodymyr; Volkov, D. S.

    The purpose of research was definition and comparison of relative parameters of sensorimotor reactions with a choice depending on a level of lateral asymmetry of hemispheres of a brain at representatives of various types of temperament OF male and female cosmonauts . These parameters were by the bases for verification of theoretical dependence for the latent period of reaction in conditions of weightlessness and overloads. The hypothesis about influence of functional asymmetry on parameters of psychomotor in sensory-motor reactions was laid in a basis of experiment. Techniques of definition of individual characters of the sensori-motor asymmetries were used, and G. Ajzenk's questionnaire EPQ adapted by Prisniakova L. Time of sensorimotor reaction has significant distinctions between representatives of different types of temperament with a various level interchemishere asymmetry OF male and female cosmonauts. With increase in expressiveness of the right hemisphere time of reaction tends to reduction at representatives of all types of temperament, the number of erroneous reactions as a whole increases also a level of achievement tends to reduction. Results of time of sensorimotor reaction correspond with parameter L. Prisniakova which characterizes individual - psychological features. .Earlier the received experimental data of constant time of processing of the information in memory at a period of a sensorimotor reactions of the man and new results for women were used for calculation of these time constants for overloads distinct from terrestrial. These data enable to predict dynamics of behavior of cosmonauts with differing sex in conditions of flight in view of their individual characteristics connected with the hemisphere asymmetry of a brain and with by a various degree of lateralization.

  19. Male Adolescent Contraceptive Utilization.

    ERIC Educational Resources Information Center

    Finkel, Madelon Lubin; Finkel, David J.

    1978-01-01

    The contraceptive utilization of a sample of sexually active, urban, high school males (Black, Hispanic, and White) was examined by anonymous questionnaire. Contraceptive use was haphazard, but White males tended to be more effective contraceptors than the other two groups. Reasons for nonuse were also studied. (Author/SJL)

  20. 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.

  1. Variance in the reproductive success of dominant male mountain gorillas.

    PubMed

    Robbins, Andrew M; Gray, Maryke; Uwingeli, Prosper; Mburanumwe, Innocent; Kagoda, Edwin; Robbins, Martha M

    2014-10-01

    Using 30 years of demographic data from 15 groups, this study estimates how harem size, female fertility, and offspring survival may contribute to variance in the siring rates of dominant male mountain gorillas throughout the Virunga Volcano Region. As predicted for polygynous species, differences in harem size were the greatest source of variance in the siring rate, whereas differences in female fertility and offspring survival were relatively minor. Harem size was positively correlated with offspring survival, even after removing all known and suspected cases of infanticide, so the correlation does not seem to reflect differences in the ability of males to protect their offspring. Harem size was not significantly correlated with female fertility, which is consistent with the hypothesis that mountain gorillas have minimal feeding competition. Harem size, offspring survival, and siring rates were not significantly correlated with the proportion of dominant tenures that occurred in multimale groups versus one-male groups; even though infanticide is less likely when those tenures end in multimale groups than one-male groups. In contrast with the relatively small contribution of offspring survival to variance in the siring rates of this study, offspring survival is a major source of variance in the male reproductive success of western gorillas, which have greater predation risks and significantly higher rates of infanticide. If differences in offspring protection are less important among male mountain gorillas than western gorillas, then the relative importance of other factors may be greater for mountain gorillas. Thus, our study illustrates how variance in male reproductive success and its components can differ between closely related species. PMID:24818867

  2. Human lung surfactant protein A exists in several different oligomeric states: oligomer size distribution varies between patient groups.

    PubMed Central

    Hickling, T. P.; Malhotra, R.; Sim, R. B.

    1998-01-01

    BACKGROUND: Lung surfactant protein A (SP-A) is a complex molecule composed of up to 18 polypeptide chains. In vivo, SP-A probably binds to a wide range of inhaled materials via the interaction of surface carbohydrates with the lectin domains of SP-A and mediates their interaction with cells as part of a natural defense system. Multiplicity of lectin domains gives high-affinity binding to carbohydrate-bearing surfaces. MATERIALS AND METHODS: Gel filtration analyses were performed on bronchoalveolar lavage (BAL) fluid samples from three patient groups: pulmonary alveolar proteinosis (n = 12), birch pollen allergy (n = 11), and healthy volunteers (n = 4). Sucrose density gradient centrifugation was employed to determine molecular weights of SP-A oligomers. SP-A was solubilized from the lipid phase to compare oligomeric state with that of water soluble SP-A. RESULTS: SP-A exists as fully assembled complexes with 18 polypeptide chains, but it is also consistently found in smaller oligomeric forms. This is true for both the water- and lipid-soluble fractions of SP-A. CONCLUSION: The three patient groups analyzed show a shift towards lower oligomeric forms of SP-A in the following sequence: healthy-pulmonary alveolar proteinosis-pollen allergy. Depolymerization would be expected to lead to loss of binding affinity for carbohydrate-rich surfaces, with loss or alteration of biological function. While there are many complex factors involved in the establishment of an allergy, it is possible that reduced participation of SP-A in clearing a potential allergen from the lungs could be an early step in the chain of events. Images Fig. 4 FIG. 6 Fig. 7 Fig. 8 PMID:9606179

  3. Does relative out-group size in neighborhoods drive down associational life of Whites in the U.S.? Testing constrict, conflict and contact theories.

    PubMed

    Savelkoul, Michael; Hewstone, Miles; Scheepers, Peer; Stolle, Dietlind

    2015-07-01

    We test whether a larger percentage of non-Whites in neighborhoods decreases associational involvement and build on earlier research in three ways. First, we explicitly consider the ethnic composition of organizations, distinguishing involvement in bridging (with out-group members) and bonding (only in-group members) organizations. Second, we start from constrict theory and test competing sets of predictions derived from conflict and contact theories to explain these relationships. Third, we examine whether relative out-group size affects involvement in different types of voluntary organizations equally. Using data from the 2005 U.S. 'Citizenship, Involvement, Democracy' survey, the percentage of non-Whites in neighborhoods is largely unrelated with associational involvement or perceived ethnic threat. However, perceiving ethnic threat is consistently negatively related with involvement in bridging organizations. Simultaneously, a larger percentage of non-Whites fosters intergroup contact, which is negatively related with perceptions of ethnic threat and involvement in bonding leisure organizations. Our results shed more light on the relationship between the relative out-group size in neighborhoods and associational involvement as well as underlying explanations for this link. PMID:26004460

  4. Development and Validation of an Older Occupant Finite Element Model of a Mid-Sized Male for Investigation of Age-related Injury Risk.

    PubMed

    Schoell, Samantha L; Weaver, Ashley A; Urban, Jillian E; Jones, Derek A; Stitzel, Joel D; Hwang, Eunjoo; Reed, Matthew P; Rupp, Jonathan D; Hu, Jingwen

    2015-11-01

    The aging population is a growing concern as the increased fragility and frailty of the elderly results in an elevated incidence of injury as well as an increased risk of mortality and morbidity. To assess elderly injury risk, age-specific computational models can be developed to directly calculate biomechanical metrics for injury. The first objective was to develop an older occupant Global Human Body Models Consortium (GHBMC) average male model (M50) representative of a 65 year old (YO) and to perform regional validation tests to investigate predicted fractures and injury severity with age. Development of the GHBMC M50 65 YO model involved implementing geometric, cortical thickness, and material property changes with age. Regional validation tests included a chest impact, a lateral impact, a shoulder impact, a thoracoabdominal impact, an abdominal bar impact, a pelvic impact, and a lateral sled test. The second objective was to investigate age-related injury risks by performing a frontal US NCAP simulation test with the GHBMC M50 65 YO and the GHBMC M50 v4.2 models. Simulation results were compared to the GHBMC M50 v4.2 to evaluate the effect of age on occupant response and risk for head injury, neck injury, thoracic injury, and lower extremity injury. Overall, the GHBMC M50 65 YO model predicted higher probabilities of AIS 3+ injury for the head and thorax. PMID:26660751

  5. Acute phase cytokines, TAC1, and toll-like receptor4 mRNA expression and health associated with group size in veal calves.

    PubMed

    Abdelfattah, E M; Karousa, M M; Schutz, M M; Lay, D C; Marchant-Forde, J N; Eicher, S D

    2015-04-15

    Chronic stressors are a major health and well-being issue in animals. Immune status of animals under chronic stress is compromised, thus reducing disease resistance and compromising well-being of the animal. The objective of this study was to determine the influence of group size of veal calves on immune status and leukocyte mRNA expression of acute phase cytokines, toll-like receptor 4 (TLR4) and tachykinin 1 (TAC1) over a five-month finishing period. Holstein bull calves (n=168), 44±3 days of age were assigned to one of three treatments; 2, 4, or 8 calves/pen (pen space allowance of 1.82m(2)/calf). Jugular blood samples were collected at the day of grouping and then monthly for 4 months. The differential leukocyte counts were determined and mRNA was extracted from the leukocytes. Reverse transcription-qPCR was used to measure the gene expression of interleukin-1 (IL-1β), IL-1 receptor antagonist (IL-1Ra), tumor necrosis factor (TNF-α), TLR4, and TAC1 in leukocytes. Health was evaluated before grouping and monthly for 4 months. On the 1st month after grouping, veal calves that were housed in groups of 8 have greater expression of IL-1β mRNA than calves housed in groups of 4 or 2 (treatment×month, P=0.04). Also at 1 month, groups of 8 had greater TAC1 expression (P<0.05) than calves housed in groups of 4 or 2. However, the expression of IL-1Ra, TNF-α, and TLR4 were not influenced by group size. In the first month of the trial, calves in groups of 8 coughed more (P<0.05) than calves in groups of 2 and coughed more than calves in groups of 4 and 2 during the 2nd month (treatment×month, P=0.03). Calves housed in groups of 8 tended to have greater neutrophil percentage (P=0.09), neutrophil to lymphocyte ratio (P=0.06), and had lower lymphocyte percentage (P=0.06) than those housed in groups of 4 or 2. In conclusion, the number of veal calves in a group, given the same space during the finishing period did not alter IL-1Ra, TNF-α, and TLR4 mRNA expression

  6. Prediction of the mesiodistal size of unerupted canines and premolars for a group of Romanian children: a comparative study

    PubMed Central

    BOITOR, Cornel Gheorghe; STOICA, Florin; NASSER, Hamdan

    2013-01-01

    Objectives: The aim of the present study was to develop an optimization method of multiple linear regression equation (MLRE), using a genetic algorithm to determine a set of coefficients that minimize the prediction error for the sum of permanent premolars and canine dimensions in a group of young people from a central area of Romania represented by a city called Sibiu. Material and Methods: To test the proposed method, we used a multiple linear regression equation derived from the estimation method proposed by Mojers, to which we adjusted regression coefficients using the Breeder genetic algorithm. A total of 92 children were selected with complete permanent teeth with no clinically visible dental caries, proximal restorations or orthodontic treatment. A hard dental stone was made for each of these models, which was then measured with a digital calliper. The Dahlberg analyses of variance had been performed to determine the error of method, then the Correlation t Test was applied, and finally the MLRE equations were obtained using the version 16 for Windows of the SPSS program. Results: The correlation coefficient of MLRE was between 51-67% and the significance level was set at α=0.05. Comparing predictions provided by the new and respectively old method, we can conclude that the Breeder genetic algorithm is capable of providing the best values for parameters of multiple linear regression equations, and thus our equations are optimized for the best performance. Conclusion: The prediction error rates of the optimized equations using the Breeder genetic algorithm are smaller than those provided by the multiple linear regression equations proposed in the recent study. PMID:23857650

  7. Sex Education for Male Adolescent Sex Offenders in a Group Setting Led by General Psychiatry Residents: A Literature Review and Example in Practice

    ERIC Educational Resources Information Center

    Dwyer, R. Gregg; Boyd, Mary S.

    2009-01-01

    Male adolescents have been credited with a significant percentage of sex crimes in recent years. They are a heterogeneous population with offenses spanning the same range found among adult offenders. A lack of interpersonal social skills relevant to intimate relationships and inaccurate knowledge regarding appropriate sexual behaviors contribute…

  8. Ectomycorrhizal Influence on Particle Size, Surface Structure, Mineral Crystallinity, Functional Groups, and Elemental Composition of Soil Colloids from Different Soil Origins

    PubMed Central

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O–H stretching and bending, C–H stretching, C=O stretching, etc.) by 3–26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40–300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12–35% decreases in most functional groups, 15–55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P < 0.05). These different responses sharply decreased element ratios (C : O, C : N, and C : Si) in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil. PMID:23766704

  9. Male breast cancer.

    PubMed

    Jepson, A S; Fentiman, I S

    1998-01-01

    Male breast cancer is a rare disease, often with a late presentation and poor prognosis. The mainstay of treatment is modified radical mastectomy, with axillary node dissection to assess stage, prognosis and the need for adjuvant treatment. When matched for age, tumour size, grade and axillary nodal status, the prognosis is similar for males and females. Concerted efforts must be made to educate both the public and health professionals, in order to make earlier diagnoses and thereby improve prognosis. PMID:10622057

  10. Osteoporosis in Groups with Intellectual Disability.

    ERIC Educational Resources Information Center

    Center, J. R.; And Others

    1994-01-01

    Fifty-three adults with intellectual impairment referred to an endocrinology clinic in New South Wales (Australia) were measured for lumbar bone mineral density. Bone mineral density was significantly lower in this group than in an age and sex matched control group. Risk factors included male gender, physical inactivity, small body size,…

  11. Condoms - male

    MedlinePlus

    ... Rubbers; Male condoms; Contraceptive - condom; Contraception - condom; Barrier method - condom ... infections.) Latex rubber Polyurethane Condoms are the only method of birth control for men that are not ...

  12. 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.

  13. 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.

  14. Conflict over Male Parentage in Social Insects

    PubMed Central

    2004-01-01

    Mutual policing is an important mechanism that maintains social harmony in group-living organisms by suppressing the selfish behavior of individuals. In social insects, workers police one another (worker-policing) by preventing individual workers from laying eggs that would otherwise develop into males. Within the framework of Hamilton's rule there are two explanations for worker-policing behavior. First, if worker reproduction is cost-free, worker-policing should occur only where workers are more closely related to queen- than to worker-produced male eggs (relatedness hypothesis). Second, if there are substantial costs to unchecked worker reproduction, worker-policing may occur to counteract these costs and increase colony efficiency (efficiency hypothesis). The first explanation predicts that patterns of the parentage of males (male parentage) are associated with relatedness, whereas the latter does not. We have investigated how male parentage varies with colony kin structure and colony size in 50 species of ants, bees, and wasps in a phylogenetically controlled comparative analysis. Our survey revealed that queens produced the majority of males in most of the species and that workers produced more than half of the males in less than 10% of species. Moreover, we show that male parentage does not vary with relatedness as predicted by the relatedness hypothesis. This indicates that intra- and interspecific variation in male parentage cannot be accounted for by the relatedness hypothesis alone and that increased colony efficiency is an important factor responsible for the evolution of worker-policing. Our study reveals greater harmony and more complex regulation of reproduction in social insect colonies than that expected from simple theoretical expectations based on relatedness only. PMID:15328531

  15. Influence of Control Group on Effect Size in Trials of Acupuncture for Chronic Pain: A Secondary Analysis of an Individual Patient Data Meta-Analysis

    PubMed Central

    MacPherson, Hugh; Vertosick, Emily; Lewith, George; Linde, Klaus; Sherman, Karen J.; Witt, Claudia M.; Vickers, Andrew J.

    2014-01-01

    Background In a recent individual patient data meta-analysis, acupuncture was found to be superior to both sham and non-sham controls in patients with chronic pain. In this paper we identify variations in types of sham and non-sham controls used and analyze their impact on the effect size of acupuncture. Methods Based on literature searches of acupuncture trials involving patients with headache and migraine, osteoarthritis, and back, neck and shoulder pain, 29 trials met inclusion criteria, 20 involving sham controls (n = 5,230) and 18 non-sham controls (n = 14,597). For sham controls, we analysed non-needle sham, penetrating sham needles and non-penetrating sham needles. For non-sham controls, we analysed non-specified routine care and protocol-guided care. Using meta-regression we explored impact of choice of control on effect of acupuncture. Findings Acupuncture was significantly superior to all categories of control group. For trials that used penetrating needles for sham control, acupuncture had smaller effect sizes than for trials with non-penetrating sham or sham control without needles. The difference in effect size was −0.45 (95% C.I. −0.78, −0.12; p = 0.007), or −0.19 (95% C.I. −0.39, 0.01; p = 0.058) after exclusion of outlying studies showing very large effects of acupuncture. In trials with non-sham controls, larger effect sizes associated with acupuncture vs. non-specified routine care than vs. protocol-guided care. Although the difference in effect size was large (0.26), it was not significant with a wide confidence interval (95% C.I. −0.05, 0.57, p = 0.1). Conclusion Acupuncture is significantly superior to control irrespective of the subtype of control. While the choice of control should be driven by the study question, our findings can help inform study design in acupuncture, particularly with respect to sample size. Penetrating needles appear to have important physiologic activity. We recommend that this type of

  16. Condoms - male

    MedlinePlus

    ... PREGNANCY? If the sperm contained in a male's semen reach a woman's vagina, pregnancy may occur. Condoms ... receptacle) on the end of it (to collect semen), place the condom against the top of the ...

  17. Rival assessment among northern elephant seals: evidence of associative learning during male-male contests.

    PubMed

    Casey, Caroline; Charrier, Isabelle; Mathevon, Nicolas; Reichmuth, Colleen

    2015-08-01

    Specialized signals emitted by competing males often convey honest information about fighting ability. It is generally believed that receivers use these signals to directly assess their opponents. Here, we demonstrate an alternative communication strategy used by males in a breeding system where the costs of conflict are extreme. We evaluated the acoustic displays of breeding male northern elephant seals (Mirounga angustirostris), and found that social knowledge gained through prior experience with signallers was sufficient to maintain structured dominance relationships. Using sound analysis and playback experiments with both natural and modified signals, we determined that males do not rely on encoded information about size or dominance status, but rather learn to recognize individual acoustic signatures produced by their rivals. Further, we show that behavioural responses to competitors' calls are modulated by relative position in the hierarchy: the highest ranking (alpha) males defend their harems from all opponents, whereas mid-ranking (beta) males respond differentially to familiar challengers based on the outcome of previous competitive interactions. Our findings demonstrate that social knowledge of rivals alone can regulate dominance relationships among competing males within large, spatially dynamic social groups, and illustrate the importance of combining descriptive and experimental methods when deciphering the biological relevance of animal signals. PMID:26361553

  18. Hunting by male lions: ecological influences and socioecological implications.

    PubMed

    Funston; Mills; Biggs; Richardson

    1998-12-01

    In the Kruger National Park, male lions, Panthera leo, acquire most of their food by hunting rather than scavenging. This study, the most intensive to date of male lion ecology, showed that in savanna woodlands, with high buffalo, Syncerus caffer, densities, male lions were frequent and successful hunters. The main prey species of all male group types, but particularly nonterritorial males, was buffalo. By contrast, females preyed more frequently on the most abundant medium-sized ungulates, such as wildebeest, Connochaetes taurinus, and zebra, Equus burchelli. Thus intraspecific prey selection separation was based primarily on intersexual and, to a lesser extent, social differences. Furthermore, both nonterritorial males and pride females located their favoured prey, buffalo and medium-sized ungulates, respectively, more often than other prey. We investigated the influence of several ecological variables on the socioecology of male lions, particularly as we had determined that territorial males spent little time with their pride females and tended to hunt by themselves in their respective male coalitions. Further analysis showed that in a range of ecosystems in southern and eastern Africa the proportion of time territorial males spent with, and thus scavenged from, their pride females was strongly influenced by vegetation structure, and therefore probably by the assemblage of available ungulates. In open systems, territorial males were, therefore, likely to be encountered with pride females, whereas in more wooded areas they were likely to be encountered away from their pride females. We suggest that this is because vegetation structure influences food/prey availability and hunting success and influences territory maintenance and/or cub defence. (c) 1998 The Association for the Study of Animal Behaviour. PMID:9933529

  19. Developmental Environment Effects on Sexual Selection in Male and Female Drosophila melanogaster.

    PubMed

    Morimoto, Juliano; Pizzari, Tommaso; Wigby, Stuart

    2016-01-01

    The developmental environment can potentially alter the adult social environment and influence traits targeted by sexual selection such as body size. In this study, we manipulated larval density in male and female Drosophila melanogaster, which results in distinct adult size phenotypes-high (low) densities for small (large) adults-and measured sexual selection in experimental groups consisting of adult males and females from high, low, or a mixture of low and high larval densities. Overall, large adult females (those reared at low larval density) had more matings, more mates and produced more offspring than small females (those reared at high larval density). The number of offspring produced by females was positively associated with their number of mates (i.e. there was a positive female Bateman gradient) in social groups where female size was experimentally varied, likely due to the covariance between female productivity and mating rate. For males, we found evidence that the larval environment affected the relative importance of sexual selection via mate number (Bateman gradients), mate productivity, paternity share, and their covariances. Mate number and mate productivity were significantly reduced for small males in social environments where males were of mixed sizes, versus social environments where all males were small, suggesting that social heterogeneity altered selection on this subset of males. Males are commonly assumed to benefit from mating with large females, but in contrast to expectations we found that in groups where both the male and female size varied, males did not gain more offspring per mating with large females. Collectively, our results indicate sex-specific effects of the developmental environment on the operation of sexual selection, via both the phenotype of individuals, and the phenotype of their competitors and mates. PMID:27167120

  20. Developmental Environment Effects on Sexual Selection in Male and Female Drosophila melanogaster

    PubMed Central

    Morimoto, Juliano; Pizzari, Tommaso; Wigby, Stuart

    2016-01-01

    The developmental environment can potentially alter the adult social environment and influence traits targeted by sexual selection such as body size. In this study, we manipulated larval density in male and female Drosophila melanogaster, which results in distinct adult size phenotypes–high (low) densities for small (large) adults–and measured sexual selection in experimental groups consisting of adult males and females from high, low, or a mixture of low and high larval densities. Overall, large adult females (those reared at low larval density) had more matings, more mates and produced more offspring than small females (those reared at high larval density). The number of offspring produced by females was positively associated with their number of mates (i.e. there was a positive female Bateman gradient) in social groups where female size was experimentally varied, likely due to the covariance between female productivity and mating rate. For males, we found evidence that the larval environment affected the relative importance of sexual selection via mate number (Bateman gradients), mate productivity, paternity share, and their covariances. Mate number and mate productivity were significantly reduced for small males in social environments where males were of mixed sizes, versus social environments where all males were small, suggesting that social heterogeneity altered selection on this subset of males. Males are commonly assumed to benefit from mating with large females, but in contrast to expectations we found that in groups where both the male and female size varied, males did not gain more offspring per mating with large females. Collectively, our results indicate sex-specific effects of the developmental environment on the operation of sexual selection, via both the phenotype of individuals, and the phenotype of their competitors and mates. PMID:27167120

  1. Female mate choice in a subsocial beetle: male phenotype correlates with helping potential and offspring survival.

    PubMed

    Rasa; Bisch; Teichner

    1998-11-01

    In Parastizopus armaticeps (Tenebrionidae), a nocturnal desert beetle, the males excavate breeding burrows and maintain their moisture level while the females provision the larvae with detritus collected on the surface. The beetles court in small groups on the surface at night after rain. Male size distribution in these groups corresponded to that in the population but more large and fewer small females were present than expected and more large beetles of both sexes bred. Offspring number correlated positively with burrow depth and body length for males but not for females. Since large males dig deeper burrows, which results in higher larval survival rate, females should prefer them. In choice experiments, females selected larger males. Behavioural analyses showed that choice was not dependent on differences in male courtship activity or intermale dominance. When the mass of the smaller male was increased experimentally by a dorsally attached weight, the smaller male was preferred, females estimating male size difference by mass. Partner choice is therefore epigamic for a male phenotypic character which correlates with both parenting ability and greater reproductive success for females. Copyright 1998 The Association for the Study of Animal Behaviour. PMID:9819338

  2. Bioaccumulation of platinum group elements and characterization of their species in Lolium multiflorum by size-exclusion chromatography coupled with ICP-MS.

    PubMed

    Lesniewska, Barbara A; Messerschmidt, Jürgen; Jakubowski, Norbert; Hulanicki, Adam

    2004-04-25

    The bioaccumulation of Pt, Pd and Rh by grass grown hydroponically with nutrient solutions containing these ions at elevated (38.7 mg l(-1) Pt, 21.7 mg l(-1) Pd and 7.1 mg l(-1) Rh) and medium (3.6 mg l(-1) Pt, 4.4 mg l(-1) Pd and 0.5 mg l(-1) Rh) concentrations was studied by using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The highest bioaccumulation factors were obtained for Pd and Rh in roots and for Pt in leaves. The obtained results showed that most of the studied metals were accumulated in roots, and only a small fraction was really metabolised and transported to leaves. The multi-element capability of ICP-SFMS has been exploited to study the metabolism of platinum group elements (PGEs) in cultivated plants. The species of studied metals were extracted from roots and leaves and separated into two mass fractions by ultra-filtration. The low molecular mass (<10 kDa) fractions of the root and the leaf extracts were investigated by size-exclusion chromatography (SEC) coupled on-line to ICP-SFMS. The presence of Ca, Cu, S and C in the same fractions as Pt, Pd and Rh may indicate the interaction of PGEs with phytochelatins and carbohydrates. PMID:15081741

  3. Male Osteoporosis

    PubMed Central

    Drake, Matthew T.; Khosla, Sundeep

    2013-01-01

    Synopsis Osteoporosis is now recognized as a major threat to health in aging men. Morbidity and mortality, particularly following hip fracture, are substantial. Whereas trabecular bone loss starts in early adulthood, loss of cortical bone only appears to occur from mid-life onwards. Declining bioavailable estradiol levels play an integral role in male age-associated bone loss. Both pharmacologic and supportive care interventions are important for optimal care in men at increased fracture risk. PMID:22877433

  4. RPI-AM and RPI-AF, a pair of mesh-based, size-adjustable adult male and female computational phantoms using ICRP-89 parameters and their calculations for organ doses from monoenergetic photon beams

    NASA Astrophysics Data System (ADS)

    Zhang, Juying; Hum Na, Yong; Caracappa, Peter F.; Xu, X. George

    2009-10-01

    This paper describes the development of a pair of adult male and adult female computational phantoms that are compatible with anatomical parameters for the 50th percentile population as specified by the International Commission on Radiological Protection (ICRP). The phantoms were designed entirely using polygonal mesh surfaces—a Boundary REPresentation (BREP) geometry that affords the ability to efficiently deform the shape and size of individual organs, as well as the body posture. A set of surface mesh models, from Anatomium™ 3D P1 V2.0, including 140 organs (out of 500 available) was adopted to supply the basic anatomical representation at the organ level. The organ masses were carefully adjusted to agree within 0.5% relative error with the reference values provided in the ICRP Publication 89. The finalized phantoms have been designated the RPI adult male (RPI-AM) and adult female (RPI-AF) phantoms. For the purposes of organ dose calculations using the MCNPX Monte Carlo code, these phantoms were subsequently converted to voxel formats. Monoenergetic photons between 10 keV and 10 MeV in six standard external photon source geometries were considered in this study: four parallel beams (anterior-posterior, posterior-anterior, left lateral and right lateral), one rotational and one isotropic. The results are tabulated as fluence-to-organ-absorbed-dose conversion coefficients and fluence-to-effective-dose conversion coefficients and compared against those derived from the ICRP computational phantoms, REX and REGINA. A general agreement was found for the effective dose from these two sets of phantoms for photon energies greater than about 300 keV. However, for low-energy photons and certain individual organs, the absorbed doses exhibit profound differences due to specific anatomical features. For example, the position of the arms affects the dose to the lung by more than 20% below 300 keV in the lateral source directions, and the vertical position of the testes

  5. RPI-AM and RPI-AF, a pair of mesh-based, size-adjustable adult male and female computational phantoms using ICRP-89 parameters and their calculations for organ doses from monoenergetic photon beams

    PubMed Central

    Zhang, Juying; Na, Yong Hum; Caracappa, Peter F; Xu, X George

    2010-01-01

    This paper describes the development of a pair of adult male and adult female computational phantoms that are compatible with anatomical parameters for the 50th percentile population as specified by the International Commission on Radiological Protection (ICRP). The phantoms were designed entirely using polygonal mesh surfaces—a Boundary REPresentation (BREP) geometry that affords the ability to efficiently deform the shape and size of individual organs, as well as the body posture. A set of surface mesh models, from Anatomium™ 3D P1 V2.0, including 140 organs (out of 500 available) was adopted to supply the basic anatomical representation at the organ level. The organ masses were carefully adjusted to agree within 0.5% relative error with the reference values provided in the ICRP Publication 89. The finalized phantoms have been designated the RPI adult male (RPI-AM) and adult female (RPI-AF) phantoms. For the purposes of organ dose calculations using the MCNPX Monte Carlo code, these phantoms were subsequently converted to voxel formats. Monoenergetic photons between 10 keV and 10 MeV in six standard external photon source geometries were considered in this study: four parallel beams (anterior–posterior, posterior–anterior, left lateral and right lateral), one rotational and one isotropic. The results are tabulated as fluence-to-organ-absorbed-dose conversion coefficients and fluence-to-effective-dose conversion coefficients and compared against those derived from the ICRP computational phantoms, REX and REGINA. A general agreement was found for the effective dose from these two sets of phantoms for photon energies greater than about 300 keV. However, for low-energy photons and certain individual organs, the absorbed doses exhibit profound differences due to specific anatomical features. For example, the position of the arms affects the dose to the lung by more than 20% below 300 keV in the lateral source directions, and the vertical position of the testes

  6. Sympatric speciation as a consequence of male pregnancy in seahorses

    PubMed Central

    Jones, Adam G.; Moore, Glenn I.; Kvarnemo, Charlotta; Walker, DeEtte; Avise, John C.

    2003-01-01

    The phenomenon of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) undeniably has sculpted the course of behavioral evolution in these fishes. Here we explore another potentially important but previously unrecognized consequence of male pregnancy: a predisposition for sympatric speciation. We present microsatellite data on genetic parentage that show that seahorses mate size-assortatively in nature. We then develop a quantitative genetic model based on these empirical findings to demonstrate that sympatric speciation indeed can occur under this mating regime in response to weak disruptive selection on body size. We also evaluate phylogenetic evidence bearing on sympatric speciation by asking whether tiny seahorse species are sister taxa to large sympatric relatives. Overall, our results indicate that sympatric speciation is a plausible mechanism for the diversification of seahorses, and that assortative mating (in this case as a result of male parental care) may warrant broader attention in the speciation process for some other taxonomic groups as well. PMID:12732712

  7. Report on the meetings of the small and medium size reactor (SMR) expert group of the organization for economic cooperation and development (OECD), Paris, France, June 15-16, 1989: Foreign trip report

    SciTech Connect

    Rowan, W.J.

    1989-07-05

    The traveler attended the meeting of the Small and Medium Size Reactor (SMR) Expert Group of the OECD. The group agreed to identify the potential for SMRs in OECD countries and to document their views in a report. The group also developed and initiated a plan and schedule for this effort. This report describes significant activities that took place during the meeting and presents relevant information that has been collected in recent international studies.

  8. Eating Disorders in Adolescent Males

    ERIC Educational Resources Information Center

    Ray, Shannon L.

    2004-01-01

    Research indicates that the primary onset of eating disorders occurs in adolescence and that there is a growing prevalence of adolescent males with eating disorders. This article describes the eating disorders of anorexia nervosa and bulimia nervosa as they relate to adolescent males. Diagnostic criteria, at-risk groups, and implications for…

  9. A reliable morphological method to assess the age of male Anopheles gambiae

    PubMed Central

    Huho, Bernadette J; Ng'habi, Kija R; Killeen, Gerry F; Nkwengulila, Gamba; Knols, Bart GJ; Ferguson, Heather M

    2006-01-01

    Background Release of genetically-modified (GM) or sterile male mosquitoes for malaria control is hampered by inability to assess the age and mating history of free-living male Anopheles. Methods Age and mating-related changes in the reproductive system of male Anopheles gambiae were quantified and used to fit predictive statistical models. These models, based on numbers of spermatocysts, relative size of sperm reservoir and presence/absence of a clear area around the accessory gland, were evaluated using an independent sample of mosquitoes whose status was blinded during the experiment. Results The number of spermatocysts in male testes decreased with age, and the relative size of their sperm reservoir increased. The presence of a clear area around accessory glands was also linked to age and mating status. A quantitative model was able to categorize males from the blind trial into age groups of young (≤ 4 days) and old (> 4 days) with an overall efficiency of 89%. Using the parameters of this model, a simple table was compiled that can be used to predict male age. In contrast, mating history could not be reliably assessed as virgins could not be distinguished from mated males. Conclusion Simple assessment of a few morphological traits which are easily collected in the field allows accurate age-grading of male An. gambiae. This simple, yet robust, model enables evaluation of demographic patterns and mortality in wild and released males in populations targeted by GM or sterile male-based control programmes. PMID:16872516

  10. What a maleless group can tell us about the constraints on female transfer in Thomas's langurs (Presbytis thomasi).

    PubMed

    Steenbeek, R

    1996-01-01

    During a long-term study of wild Thomas's langurs (Presbytis thomasi), the adult male of one of the bisexual study groups, group M, suddenly disappeared. Just after the adult male's disappearance, the females of group M actively avoided other groups and sometimes formed subgroups. Infants were attacked by extra-group males and 1 infant disappeared. After about 2 months, the females initiated affiliative interactions with males of neighbouring groups. Aggressive interactions between females of group M and females of other groups were also observed. Females of group M did not leave their home range in spite of efforts by adult males to lead them away. After about 4.5 months, a former all-male band member joined group M. The coincidences of this case suggest that increased infanticide risk, increased food competition, loss of knowledge of the home range and loss of established social relationships could be important constraints on female transfer. A comparison with 5 other studies of 1-male groups in which the adult male disappeared showed that proximate factors, such as the presence of infants, the size of neighbouring groups and the presence of extra-group males, influence female decisions. PMID:9159917

  11. Techniques of Male Circumcision

    PubMed Central

    Abdulwahab-Ahmed, Abdullahi; Mungadi, Ismaila A.

    2013-01-01

    Male circumcision is a controversial subject in surgical practice. There are, however, clear surgical indications of this procedure. The American Academy of Pediatrics (AAP) recommends newborn male circumcision for its preventive and public health benefits that has been shown to outweigh the risks of newborn male circumcision. Many surgical techniques have been reported. The present review discusses some of these techniques with their merits and drawbacks. This is an attempt to inform the reader on surgical aspects of male circumcision aiding in making appropriate choice of a technique to offer patients. Pubmed search was done with the keywords: Circumcision, technique, complications, and history. Relevant articles on techniques of circumcision were selected for the review. Various methods of circumcision including several devices are in use for male circumcision. These methods can be grouped into three: Shield and clamp, dorsal slit, and excision. The device methods appear favored in the pediatric circumcision while the risk of complications increases with increasing age of the patient at surgery. PMID:24470842

  12. Producing Monosex Male Populations for Catfish Culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are a number of uses for the preferential production of male catfish in aquaculture operations. Several studies have demonstrated that male channel catfish grow faster than female fish and would be expected to reach market size faster. Also, in the production of hybrid catfish male blue catf...

  13. An Alternative to Cohen's Standardized Mean Difference Effect Size: A Robust Parameter and Confidence Interval in the Two Independent Groups Case

    ERIC Educational Resources Information Center

    Algina, James; Keselman, H. J.; Penfield, Randall D.

    2005-01-01

    The authors argue that a robust version of Cohen's effect size constructed by replacing population means with 20% trimmed means and the population standard deviation with the square root of a 20% Winsorized variance is a better measure of population separation than is Cohen's effect size. The authors investigated coverage probability for…

  14. Male breast cancer.

    PubMed

    Ottini, Laura; Palli, Domenico; Rizzo, Sergio; Federico, Mario; Bazan, Viviana; Russo, Antonio

    2010-02-01

    Male breast cancer (MaleBC) is a rare disease, accounting for <1% of all male tumors. During the last few years, there has been an increase in the incidence of this disease, along with the increase in female breast cancer (FBC). Little is known about the etiology of MaleBC: hormonal, environmental and genetic factors have been reported to be involved in its pathogenesis. Major risk factors include clinical disorders carrying hormonal imbalances, radiation exposure and, in particular, a positive family history (FH) for BC, the latter suggestive of genetic susceptibility. Rare mutations in high-penetrance genes (BRCA1 and BRCA2) confer a high risk of BC development; low-penetrance gene mutations (i.e. CHEK-2) are more common but involve a lower risk increase. About 90% of all male breast tumors have proved to be invasive ductal carcinomas, expressing high levels of hormone receptors with evident therapeutic returns. The most common clinical sign of BC onset in men is a painless palpable retroareolar lump, which should be evaluated by means of mammography, ultrasonography and core biopsy or fine needle aspiration (FNA). To date, there are no published data from prospective randomized trials supporting a specific therapeutic approach in MaleBC. Tumor size together with the number of axillary nodes involved are the main prognostic factors and should guide the treatment choice. Locoregional approaches include surgery and radiotherapy (RT), depending upon the initial clinical presentation. When systemic treatment (adjuvant, neoadjuvant and metastatic) is delivered, the choice between hormonal and or chemotherapy (CT) should depend upon the clinical and biological features, according to the FBC management guidelines. However great caution is required because of high rates of age-related comorbidities. PMID:19427229

  15. Male contraception.

    PubMed

    Chao, Jing; Page, Stephanie T; Anderson, Richard A

    2014-08-01

    Clear evidence shows that many men and women would welcome new male methods of contraception, but none have become available. The hormonal approach is based on suppression of gonadotropins and thus of testicular function and spermatogenesis, and has been investigated for several decades. This approach can achieve sufficient suppression of spermatogenesis for effective contraception in most men, but not all; the basis for these men responding insufficiently is unclear. Alternatively, the non-hormonal approach is based on identifying specific processes in sperm development, maturation and function. A range of targets has been identified in animal models, and targeted effectively. This approach, however, remains in the pre-clinical domain at present. There are, therefore, grounds for considering that safe, effective and reversible methods of contraception for men can be developed. PMID:24947599

  16. Male contraception

    PubMed Central

    Chao, Jing; Page, Stephanie T.; Anderson, Richard A.

    2015-01-01

    Clear evidence shows that many men and women would welcome new male methods of contraception, but none have become available. The hormonal approach is based on suppression of gonadotropins and thus of testicular function and spermatogenesis, and has been investigated for several decades. This approach can achieve sufficient suppression of spermatogenesis for effective contraception in most men, but not all; the basis for these men responding insufficiently is unclear. Alternatively, the nonhormonal approach is based on identifying specific processes in sperm development, maturation and function. A range of targets has been identified in animal models, and targeted effectively. This approach, however, remains in the pre-clinical domain at present. There are, therefore, grounds for considering that safe, effective and reversible methods of contraception for men can be developed. PMID:24947599

  17. Repeated evolution of male sacrifice behavior in spiders correlated with genital mutilation.

    PubMed

    Miller, Jeremy A

    2007-06-01

    According to sexual cannibalism theory, male complicity in terminal mating can be adaptive when the male's future reproductive value is low relative to the benefits of self sacrifice. Spiders and insects that exhibit male sacrifice behavior (either complicity in cannibalism or spontaneous death associated with copulation) often also have male genitalia that stereotypically become broken or disfigured the first time they are used for copulation, potentially lowering his future reproductive value. Theoretical work on monogamy has identified male bias in the effective sex ratio as a precursor to the evolution of monogamy (including male sacrifice) as an adaptive form of paternity protection. Using phylogeny-based statistics and drawing on several phylogenetic studies of araneoid spiders, I investigate relationships between male sacrifice behavior, genital mutilation, extreme sexual size dimorphism, and the accumulation of multiple males in the female web (as an indicator of a male-based effective sex ratio). This investigation focuses on araneoid spiders because several independent origins of sacrifice behavior are known for this group and the phylogenetic structure of the lineage is relatively well studied. I report that male genital mutilation is significantly correlated with sacrifice behavior and argue that this finding is consistent with sexual cannibalism theory. Male sacrifice behavior is also correlated with male accumulation, a result that is consistent with theoretical work on the evolution of monogamy. Male accumulation and extreme sexual size dimorphism are correlated suggesting that sex-based differences in maturation time can lead to a male biased effective sex ratio. Similar patterns of correlated characters may hold for some insect taxa. Studying traits that have appeared independently in multiple lineages is a powerful method for developing general theories about the evolution of biological phenomena. PMID:17542841

  18. Effects of pore sizes and oxygen-containing functional groups on desulfurization activity of Fe/NAC prepared by ultrasonic-assisted impregnation

    NASA Astrophysics Data System (ADS)

    Shu, Song; Guo, Jia-Xiu; Liu, Xiao-Li; Wang, Xue-Jiao; Yin, Hua-Qiang; Luo, De-Ming

    2016-01-01

    A series of Fe-loaded activated carbons treated by HNO3 (Fe/NAC) were prepared by incipient impregnation method with or without ultrasonic assistance and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy disperse spectroscope (SEM-EDS), transmission electron microscopy (TEM) and N2 adsorption/desorption. The desulfurization activities were evaluated at a fixed bed reactor under a mixed gas simulated from flue gas. The results showed that desulfurization activity from excellent to poor is as follows: Fe/NAC-60 > Fe/NAC-80 > Fe/NAC-30 > Fe/NAC-15 > Fe/NAC-0 > Fe/NAC-100 > NAC. Fe/NAC-60 exhibits the best desulfurization activity and has breakthrough sulfur capacity of 319 mg/g and breakthrough time of 540 min. The introduction of ultrasonic oscillation does not change the form of Fe oxides on activated carbon but can change the dispersion and relative contents of Fe3O4. The types of oxygen-containing functional groups have no obvious change for all samples but the texture properties show some differences when they are oscillated for different times. The fresh Fe/NAC-60 has a surface area of 1045 m2/g and total pore volume of 0.961 cm3/g with micropore volume of 0.437 cm3/g and is larger than Fe/NAC-0 (823 m2/g, 0.733 and 0.342 cm3/g). After desulfurization, surface area and pore volume of all samples decrease significantly, and those of the exhausted Fe/NAC-60 decrease to 233 m2/g and 0.481 cm3/g, indicating that some byproducts deposit on surface to cover pores. Pore size distribution influences SO2 adsorption, and fresh Fe/NAC-60 has more pore widths centralized at about 0.7 nm and 1.0-2.0 nm and corresponds to an excellent desulfurization activity, showing that micropore is conducive to the removal of SO2.

  19. Male mating biology

    PubMed Central

    Howell, Paul I; Knols, Bart GJ

    2009-01-01

    Before sterile mass-reared mosquitoes are released in an attempt to control local populations, many facets of male mating biology need to be elucidated. Large knowledge gaps exist in how both sexes meet in space and time, the correlation of male size and mating success and in which arenas matings are successful. Previous failures in mosquito sterile insect technique (SIT) projects have been linked to poor knowledge of local mating behaviours or the selection of deleterious phenotypes during colonisation and long-term mass rearing. Careful selection of mating characteristics must be combined with intensive field trials to ensure phenotypic characters are not antagonistic to longevity, dispersal, or mating behaviours in released males. Success has been achieved, even when colonised vectors were less competitive, due in part to extensive field trials to ensure mating compatibility and effective dispersal. The study of male mating biology in other dipterans has improved the success of operational SIT programmes. Contributing factors include inter-sexual selection, pheromone based attraction, the ability to detect alterations in local mating behaviours, and the effects of long-term colonisation on mating competitiveness. Although great strides have been made in other SIT programmes, this knowledge may not be germane to anophelines, and this has led to a recent increase in research in this area. PMID:19917078

  20. 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

  1. Male chest enhancement: pectoral implants.

    PubMed

    Benito-Ruiz, J; Raigosa, J M; Manzano-Surroca, M; Salvador, L

    2008-01-01

    The authors present their experience with the pectoral muscle implant for male chest enhancement in 21 patients. The markings and technique are thoroughly described. The implants used were manufactured and custom made. The candidates for implants comprised three groups: group 1 (18 patients seeking chest enhancement), group 2 (1 patient with muscular atrophy), and group 3 (2 patients with muscular injuries). Because of the satisfying results obtained, including significant enhancement of the chest contour and no major complications, this technique is used for an increasing number of male cosmetic surgeries. PMID:17676376

  2. Benefits of size dimorphism and copulatory silk wrapping in the sexually cannibalistic nursery web spider, Pisaurina mira.

    PubMed

    Anderson, Alissa G; Hebets, Eileen A

    2016-02-01

    In sexually cannibalistic animals, male fitness is influenced not only by successful mate acquisition and egg fertilization, but also by avoiding being eaten. In the cannibalistic nursery web spider, Pisaurina mira, the legs of mature males are longer in relation to their body size than those of females, and males use these legs to aid in wrapping a female's legs with silk prior to and during copulation. We hypothesized that elongated male legs and silk wrapping provide benefits to males, in part through a reduced likelihood of sexual cannibalism. To test this, we paired females of random size with males from one of two treatment groups-those capable of silk wrapping versus those incapable of silk wrapping. We found that males with relatively longer legs and larger body size were more likely to mate and were less likely to be cannibalized prior to copulation. Regardless of relative size, males capable of silk wrapping were less likely to be cannibalized during or following copulation and had more opportunities for sperm transfer (i.e. pedipalpal insertions). Our results suggest that male size and copulatory silk wrapping are sexually selected traits benefiting male reproductive success. PMID:26911340

  3. Do Males Form Social Associations Based on Sexual Attractiveness in a Fission-Fusion Fish Society?

    PubMed

    Auge, Anne-Christine; Auld, Heather L; Sherratt, Thomas N; Godin, Jean-Guy J

    2016-01-01

    Recent theory predicts that males should choose social environments that maximize their relative attractiveness to females by preferentially associating with less attractive rivals, so as to enhance their mating success. Using the Trinidadian guppy (Poecilia reticulata), a highly social species, we tested for non-random social associations among males in mixed-sex groups based on two phenotypic traits (body length and coloration) that predict relative sexual attractiveness to females and sexual (sperm) competitiveness. Based on a well-replicated laboratory dichotomous-choice test of social group preference, we could not reject the null hypothesis that focal males chose randomly between a mixed-sex group that comprised a female and a rival male that was less sexually attractive than themselves and another mixed-sex group containing a sexually more attractive male. The same conclusion was reached when females were absent from the two groups. As might be expected from these laboratory findings, free-ranging males in the field were not assorted by either body length or colour in mixed-sex shoals. The apparent lack of an evolved and expressed preference in wild male guppies from our study population to form social associations with other males based on their relative sexual attractiveness and competitiveness might be due to the fission-fusion dynamics of guppy shoals in nature. Such social dynamics likely places constraints on the formation of stable phenotype-based social associations among males. This possibility is supported by a simulation model which assumes group departure rules based on relative body size and coloration in males. PMID:26986565

  4. Challenges of flow-cytometric estimation of nuclear genome size in orchids, a plant group with both whole-genome and progressively partial endoreplication.

    PubMed

    Trávníček, Pavel; Ponert, Jan; Urfus, Tomáš; Jersáková, Jana; Vrána, Jan; Hřibová, Eva; Doležel, Jaroslav; Suda, Jan

    2015-10-01

    Nuclear genome size is an inherited quantitative trait of eukaryotic organisms with both practical and biological consequences. A detailed analysis of major families is a promising approach to fully understand the biological meaning of the extensive variation in genome size in plants. Although Orchidaceae accounts for ∼10% of the angiosperm diversity, the knowledge of patterns and dynamics of their genome size is limited, in part due to difficulties in flow cytometric analyses. Cells in various somatic tissues of orchids undergo extensive endoreplication, either whole-genome or partial, and the G1-phase nuclei with 2C DNA amounts may be lacking, resulting in overestimated genome size values. Interpretation of DNA content histograms is particularly challenging in species with progressively partial endoreplication, in which the ratios between the positions of two neighboring DNA peaks are lower than two. In order to assess distributions of nuclear DNA amounts and identify tissue suitable for reliable estimation of nuclear DNA content, we analyzed six different tissue types in 48 orchid species belonging to all recognized subfamilies. Although traditionally used leaves may provide incorrect C-values, particularly in species with progressively partial endoreplication, young ovaries and pollinaria consistently yield 2C and 1C peaks of their G1-phase nuclei, respectively, and are, therefore, the most suitable parts for genome size studies in orchids. We also provide new DNA C-values for 22 orchid genera and 42 species. Adhering to the proposed methodology would allow for reliable genome size estimates in this largest plant family. Although our research was limited to orchids, the need to find a suitable tissue with dominant 2C peak of G1-phase nuclei applies to all endopolyploid species. PMID:25929591

  5. Roles of participation and feedback in group potency.

    PubMed

    Gamero, Nuria; Peiró, José M; Zornoza, Ana; Picazo, Carmen

    2009-08-01

    The roles of group participation and group performance feedback were examined as antecedents of group potency, i.e., beliefs shared among a work group's members about the general effectiveness of the work group. Also examined were how group participation and the congruence of the feedback received from different sources about performance predicted convergence in members' beliefs about group effectiveness. The sample comprised 61 work groups of professionals involved in Master in Business Administration (MBA) programs (284 participants). Mean group size was 4.6 members (SD = .58). 65% of participants were male, and 51% were between 30 and 40 years of age. Data were gathered at two measurement times. Increases in group participation were positively related to increases in group potency and the convergence in beliefs about group effectiveness among group members over time. Results supported the premise that group performance feedback is an antecedent of changes in group potency over time. PMID:19810455

  6. Reproductive sharing in relation to group and colony-level attributes in a cooperative breeding fish

    PubMed Central

    Hellmann, Jennifer K.; Ligocki, Isaac Y.; O'Connor, Constance M.; Reddon, Adam R.; Garvy, Kelly A.; Marsh-Rollo, Susan E.; Gibbs, H. Lisle; Balshine, Sigal; Hamilton, Ian M.

    2015-01-01

    The degree to which group members share reproduction is dictated by both within-group (e.g. group size and composition) and between-group (e.g. density and position of neighbours) characteristics. While many studies have investigated reproductive patterns within social groups, few have simultaneously explored how within-group and between-group social structure influence these patterns. Here, we investigated how group size and composition, along with territory density and location within the colony, influenced parentage in 36 wild groups of a colonial, cooperatively breeding fish Neolamprologus pulcher. Dominant males sired 76% of offspring in their group, whereas dominant females mothered 82% of offspring in their group. Subordinate reproduction was frequent, occurring in 47% of sampled groups. Subordinate males gained more paternity in groups located in high-density areas and in groups with many subordinate males. Dominant males and females in large groups and in groups with many reproductively mature subordinates had higher rates of parentage loss, but only at the colony edge. Our study provides, to our knowledge, the first comprehensive quantification of reproductive sharing among groups of wild N. pulcher, a model species for the study of cooperation and social behaviour. Further, we demonstrate that the frequency of extra-pair parentage differs across small social and spatial scales. PMID:26136450

  7. Higher relatedness mitigates mortality in a nematode with lethal male fighting.

    PubMed

    Kapranas, A; Maher, A M D; Griffin, C T

    2016-02-01

    According to kin selection theory, individuals show less aggression towards their relatives. Limited dispersal promotes interactions among relatives but also increases competition among them. The evolution of cooperation in viscous populations has been subject of mainly theoretical exploration. We investigated the influence of relatedness on aggression in males of entomopathogenic nematode Steinernema longicaudum that engage in lethal fighting. In a series of in vitro experiments, we found that both competitor male group size and relatedness influence male mortality rates. Higher relatedness led to progressively lower rates of male mortality. In experimentally infected insects, wherein large numbers of males and females interact, the proportion of dead and paralysed (= terminally injured) males was higher when infection was established by infective juveniles originating from a mixture of three lines than in those infected by a single line. The results collectively show that Steinernema longicaudum males recognize their kin and consequently male mortality rates are lower in groups consisting of more related males. Furthermore, this monotonic negative relationship between aggression and relatedness suggests that kin selection benefits are still substantial even under extreme competition. Our experiments also suggest that kin recognition in entomopathogenic nematodes has a genetic basis rather than being strictly based on environmental cues. We discuss our findings within the theoretical context of the evolution of altruistic/cooperative behaviour in structured populations. PMID:26548351

  8. Male Puberty Rites: A Path Analytic Model.

    ERIC Educational Resources Information Center

    Kitahara, Michio

    1982-01-01

    Studies two determinants of male puberty rites: communitywide exclusive male work groups and polygyny which act as an extension of male subculture; and sexual integration in the division of labor and distant father-child relationship which act to reduce the distance between the sexes. (Author/RC)

  9. The effect of size and sex ratio experiences on reproductive competition in Nicrophorus vespilloides burying beetles in the wild.

    PubMed

    Hopwood, P E; Moore, A J; Tregenza, T; Royle, N J

    2016-03-01

    Male parents face a choice: should they invest more in caring for offspring or in attempting to mate with other females? The most profitable course depends on the intensity of competition for mates, which is likely to vary with the population sex ratio. However, the balance of pay-offs may vary among individual males depending on their competitive prowess or attractiveness. We tested the prediction that sex ratio and size of the resource holding male provide cues regarding the level of mating competition prior to breeding and therefore influence the duration of a male's biparental caring in association with a female. Male burying beetles, Nicrophorus vespilloides were reared, post-eclosion, in groups that differed in sex ratio. Experimental males were subsequently translocated to the wild, provided with a breeding resource (carcass) and filmed. We found no evidence that sex ratio cues prior to breeding affected future parental care behaviour but males that experienced male-biased sex ratios took longer to attract wild mating partners. Smaller males attracted a higher proportion of females than did larger males, securing significantly more monogamous breeding associations as a result. Smaller males thus avoided competitive male-male encounters more often than larger males. This has potential benefits for their female partners who avoid both intrasexual competition and direct costs of higher mating frequency associated with competing males. PMID:26749372

  10. Sexual conflict. The evolution of infanticide by males in mammalian societies.

    PubMed

    Lukas, Dieter; Huchard, Elise

    2014-11-14

    Male mammals often kill conspecific offspring. The benefits of such infanticide to males, and its costs to females, probably vary across mammalian social and mating systems. We used comparative analyses to show that infanticide primarily evolves in social mammals in which reproduction is monopolized by a minority of males. It has not promoted social counterstrategies such as female gregariousness, pair living, or changes in group size and sex ratio, but is successfully prevented by female sexual promiscuity, a paternity dilution strategy. These findings indicate that infanticide is a consequence, rather than a cause, of contrasts in mammalian social systems affecting the intensity of sexual conflict. PMID:25395534

  11. Male–male aggression peaks at intermediate relatedness in a social spider mite

    PubMed Central

    Sato, Yukie; Egas, Martijn; Sabelis, Maurice W; Mochizuki, Atsushi

    2013-01-01

    Abstract Theory predicts that when individuals live in groups or colonies, male–male aggression peaks at intermediate levels of local average relatedness. Assuming that aggression is costly and directed toward nonrelatives and that competition for reproduction acts within the colony, benefits of aggressive behavior are maximized in colonies with a mix of related and unrelated competitors because aggression hurts nonkin often, thereby favoring reproduction of kin. This leads to a dome-shaped relation between male–male aggression and average relatedness. This prediction has been tested with bacteria in the laboratory, but not with organisms in the field. We study how male–male aggression varies with relatedness in the social spider mite Stigmaeopsis miscanthi. We sampled 25 populations across a wide geographic range between Taiwan and Japan, representing a gradient of high to low within-population relatedness. For each population the weaponry of males was measured as the length of the first pair of legs, and male–male aggression was tested by placing pairs of nonsibling males together and scoring the frequency of male death over a given period. As these two morphological and behavioral variables correlate strongly, they both reflect the intensity of male–male conflict. Our data on the social spider mite show that male–male aggression as well as weapon size strongly peak at intermediate, average relatedness, thereby confirming theoretical predictions. Inclusive fitness theory predicts that when individuals live in groups or colonies, aggression should peak at intermediate levels of average relatedness in the colony. Here, we study how male–male aggression varies with average relatedness in naturally occurring colonies of the social spider mite Stigmaeopsis miscanthi. In support of theory, male–male aggression and weapon size strongly peak at intermediate average relatedness. PMID:24567830

  12. Estimation of Male Gene Flow: Use Caution.

    PubMed

    Hedrick, Philip W; Singh, Sujeet; Aspi, Jouni

    2015-01-01

    Because male gene flow cannot easily be estimated directly in many organisms, Hedrick et al. (2013) provided an approach to estimate male gene flow given estimates of diploid nuclear and female differentiation. This approach appears to work well when there is lower female than male gene flow. However, in a tiger data set there was less female differentiation observed as estimated by mitochondrial DNA than expected given the observed overall nuclear diploid differentiation. To analyze these data, we suggest an alternative approach which allows incorporation of sex-specific gene flow and sex-specific effective population size. We find that the pattern of differentiation observed in tigers was consistent with a lower male than female effective population size using this alternative approach. Further, this finding is consistent with observed data in tigers where the male effective population size was 33% that of the female effective population size. PMID:26464090

  13. Evolution of body size in Galapagos marine iguanas

    PubMed Central

    Wikelski, Martin

    2005-01-01

    Body size is one of the most important traits of organisms and allows predictions of an individual's morphology, physiology, behaviour and life history. However, explaining the evolution of complex traits such as body size is difficult because a plethora of other traits influence body size. Here I review what we know about the evolution of body size in a group of island reptiles and try to generalize about the mechanisms that shape body size. Galapagos marine iguanas occupy all 13 larger islands in this Pacific archipelago and have maximum island body weights between 900 and 12 000 g. The distribution of body sizes does not match mitochondrial clades, indicating that body size evolves independently of genetic relatedness. Marine iguanas lack intra- and inter-specific food competition and predators are not size-specific, discounting these factors as selective agents influencing body size. Instead I hypothesize that body size reflects the trade-offs between sexual and natural selection. We found that sexual selection continuously favours larger body sizes. Large males establish display territories and some gain over-proportional reproductive success in the iguanas' mating aggregations. Females select males based on size and activity and are thus responsible for the observed mating skew. However, large individuals are strongly selected against during El Niño-related famines when dietary algae disappear from the intertidal foraging areas. We showed that differences in algae sward (‘pasture’) heights and thermal constraints on large size are causally responsible for differences in maximum body size among populations. I hypothesize that body size in many animal species reflects a trade-off between foraging constraints and sexual selection and suggest that future research could focus on physiological and genetic mechanisms determining body size in wild animals. Furthermore, evolutionary stable body size distributions within populations should be analysed to

  14. Tumour size over 3 cm predicts poor short-term outcomes after major liver resection for hilar cholangiocarcinoma. By the HC-AFC-2009 group

    PubMed Central

    Regimbeau, Jean Marc; Fuks, David; Pessaux, Patrick; Bachellier, Philippe; Chatelain, Denis; Diouf, Momar; Raventos, Artigas; Mantion, Georges; Gigot, Jean-Francois; Chiche, Laurence; Pascal, Gerard; Azoulay, Daniel; Laurent, Alexis; Letoublon, Christian; Boleslawski, Emmanuel; Rivoire, Michel; Mabrut, Jean-Yves; Adham, Mustapha; Le Treut, Yves-Patrice; Delpero, Jean-Robert; Navarro, Francis; Ayav, Ahmet; Boudjema, Karim; Nuzzo, Gennaro; Scotte, Michel; Farges, Olivier

    2015-01-01

    Introduction As mortality and morbidity after a curative resection remains high, it is essential to identify pre-operative factors associated with an early death after a major resection. Methods Between 1998 and 2008, we selected a population of 331 patients having undergone a major hepatectomy including segment I with a lymphadenectomy and a common bile duct resection for a proven hilar cholangiocarcinoma in 21 tertiary centres. The study's objective was to identify pre-operative predictors of early death (<12 months) after a resection. Results The study cohort consisted of 221 men and 110 women, with a median age of 61 years (range: 24–85). The post-operative mortality and morbidity rates were 8.2% and 61%, respectively. The 1-, 3- and 5-year overall survival rates were 85%, 64% and 53%, respectively. The median tumour size was 23 mm on pathology, ranging from 8 to 40. A tumour size >30 mm [odds ratio (OR) 2.471 (95% confidence interval (CI) 1.136–7.339), P = 0.001] and major post-operative complication [OR 3.369 (95% CI 1.038–10.938), P = 0.004] were independently associated with death <12 months in a multivariate analysis. Conclusion The present analysis of a series of 331 patients with hilar cholangiocarcinoma showed that tumour size >30 mm was independently associated with death <12 months. PMID:24992279

  15. Identification of male-biased microRNA-107 as a direct regulator for nuclear receptor subfamily 5 group A member 1 based on sexually dimorphic microRNA expression profiling from chicken embryonic gonads.

    PubMed

    Miao, Nan; Wang, Xin; Hou, Yue; Feng, Yanping; Gong, Yanzhang

    2016-07-01

    Several studies indicate that sexual dimorphic microRNAs (miRNAs) in chicken gonads are likely to have important roles in sexual development, but a more global understanding of the roles of miRNAs in sexual differentiation is still needed. To this end, we performed miRNA expression profiling in chicken gonads at embryonic day 5.5 (E5.5). Among the sex-biased miRNAs validated by qRT-PCR, twelve male-biased and six female-biased miRNAs were consistent with the sequencing results. Bioinformatics analysis revealed that some sex-biased miRNAs were potentially involved in gonadal development. Further functional analysis found that over-expression of miR-107 directly inhibited nuclear receptor subfamily 5 group A member 1 (NR5a1), and its downstream cytochrome P450 family 19 subfamily A, polypeptide 1 (CYP19A1). However, anti-Mullerian hormone (AMH) was not directly or indirectly regulated by miR-107. Overall results indicate that miR-107 may specifically mediate avian ovary-development by post-transcriptional regulation of NR5a1 and CYP19A1 in estrogen signaling pathways. PMID:27036932

  16. "I Would Rather Be Size 10 Than Have Straight A's": A Focus Study Group of Adolescent Girls' Wish To Be Thinner.

    ERIC Educational Resources Information Center

    Tiggemann, Marika; Gardiner, Maria; Slater, Amy

    2000-01-01

    Investigates the body concerns of adolescent girls (N=67), together with the underlying motivations for wishes to be thinner. Results of focus group studies reveal that sociocultural influences exerted the strongest pressures to be thin. The girls displayed an unexpected sophistication in their conceptualization of the role of both media effects…

  17. Summary of Working Group 7, Part II: Linac protection and collimation of megawatt micron sized 250--500 GeV electron beams

    SciTech Connect

    Irwin, J.

    1992-11-01

    The average beam powers and beam size anticipated for next generation linear colliders make them awesome tools of destruction. Systems for protection will be crucial. A scheme for linac structure protection by sacrificial collimators is presented in Section 3. No matter what precautionary measures are taken, the tails of the beam will be populated by hard coulomb collisions along the linac. To remove these halos before reaching the final focus system optics, where particle showers can blind the detector, it will be necessary to collimate these beams. Section 5 discusses the equations governing the parameters of a conventional collimation system. Wakefields determine gap sizes and lattice functions. Materials properties dictate minimum beam sizes at collimators so they can withstand occasionally mis-steered beams. Spoiler scattering and edge scattering effects mandate that the final doublet phase be collimated twice, and depending on the results of further tracking studies, it may be necessary to collimate each phase two times. Section 6 describes a nonlinear collimation system that can collimate beams to smaller apertures than the conventional system. The tolerances for such systems resemble final focus tolerances. Section T addresses the problem of repopulation of the tails after the collimation system. The main conclusions are that it appears possible to collimate the beams for these machines with conventional passively protected collimation systems. However the length of present designs, which collimate energy and both transverse planes and meet the requirements of complete tail scraping, exceed one kilometer per linac. A collimation system may also be desirable at the low energy end of the linac to minimize collimation of high energy particles.

  18. The formation of surface multilayers at the air-water interface from sodium polyethylene glycol monoalkyl ether sulfate/AlCl(3) solutions: the role of the size of the polyethylene oxide group.

    PubMed

    Xu, Hui; Penfold, Jeff; Thomas, Robert K; Petkov, Jordan T; Tucker, Ian; Webster, John P R

    2013-09-17

    Neutron reflectivity, NR, and surface tension, ST, have been used to study the surface adsorption properties at the air-water interface of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate (sodium lauryl ether sulfate, SLES) in the presence of Al(3+) multivalent counterions, by the addition of AlCl3. In the absence of AlCl3 and at low AlCl3 concentrations monolayer adsorption is observed. With increasing AlCl3 concentration, surface multilayer formation is observed, driven by SLES/Al(3+) complex formation. The onset of multilayer formation occurs initially as a single bilayer or a multilayer structure with a limited number of bilayers, N, ≤3, and ultimately at higher AlCl3 concentrations N is large, >20. The evolution in the surface structure is determined by the surfactant and AlCl3 concentrations, and the size of the polyethylene oxide group in the different SLES surfactants studied. From the NR data, approximate surface phase diagrams are constructed, and the evolution of the surface structure with surfactant and electrolyte concentration is shown to be dependent on the size of the polyethylene oxide group. As the polyethylene oxide group increases in size the multilayer formation requires increasingly higher surfactant and AlCl3 concentrations to promote the formation. This is attributed to the increased steric hindrance of the polyethylene oxide group disrupting SLES/Al(3+) complex formation. PMID:23968161

  19. Thyroid, spermatogenesis, and male infertility.

    PubMed

    Rajender, Singh; Monica, Marie Gray; Walter, Lee; Agarwal, Ashok

    2011-01-01

    Since the identification of thyroid hormone receptors on the testes, thyroid has been suggested to have a significant impact on the male reproductive tract, spermatogenesis, and male fertility. Several research articles on the role of thyroid in spermatogenesis or male infertility have been published in the last three decades. We conducted an exhaustive literature search was conducted in order to create an up-to-date review of literature. This review aims to discuss the impact of thyroid on testicular development, spermatogenesis, hypo- or hyper- thyroidism and male infertility, and the management of thyroid related abnormal semen profile. The literature revealed that thyroid significantly impacts testicular development and that abnormal thyroid profile affects semen quality and male fertility by compromising testicular size, sperm motility and ejaculate volume. A clear link exists between thyroid hormones, testicular development and spermatogenesis. Thyroid disease negatively affects spermatogenesis and consequently may cause male infertility. In such cases, infertility is reversible, but more studies need to be conducted, especially in post-pubertal males to cement the current findings. PMID:21622096

  20. A new level of complexity in the male alliance networks of Indian Ocean bottlenose dolphins (Tursiops sp.).

    PubMed

    Connor, Richard C; Watson-Capps, Jana J; Sherwin, William B; Krützen, Michael

    2011-08-23

    Male bottlenose dolphins in Shark Bay, Western Australia form two levels of alliances; two to three males cooperate to herd individual females and teams of greater than three males compete with other groups for females. Previous observation suggested two alliance tactics: small four to six member teams of relatives that formed stable pairs or trios and unrelated males in a large 14-member second-order alliance that had labile trio formation. Here, we present evidence for a third level of alliance formation, a continuum of second-order alliance sizes and no relationship between first-order alliance stability and second-order alliance size. These findings challenge the 'two alliance tactics' hypothesis and add to the evidence that Shark Bay male bottlenose dolphins engage in alliance formation that likely places considerable demands on their social cognition. PMID:21047850

  1. Living males of the ‘ancient asexual’ Darwinulidae (Ostracoda: Crustacea)

    PubMed Central

    Smith, Robin J; Kamiya, Takahiro; Horne, David J

    2006-01-01

    Three living male darwinulid ostracods of a new species of the genus Vestalenula have been found in Yakushima, Japan. This is the first report of living darwinulid males for over 100 years and their morphology casts doubt on the two previous records from the late 1800s. The presence of male darwinulids also calls into question the hypothesis that the family Darwinulidae is an exclusively ancient asexual group, reproducing without sex for over 200 million years (Myr). Male carapaces are of similar size and shape to A-1 juvenile females of the same species, suggesting that males may have been dismissed as A-1 juveniles in other living and fossil species. The antennae and fifth limbs are sexually dimorphic: the male antennae have six segments compared with five in the female and a series of putative chemical receptors originating at the extra segment boundary, while the male fifth limbs have well-developed grasping hooks, as in males of many ostracod groups. The lack of Zenker's Organ and of complex internal structures within the hemipenis contradicts previous hypotheses of the phylogenetic position of darwinulids. PMID:16777754

  2. Development of a complex amino acid supplement, Fatigue Reviva™, for oral ingestion: initial evaluations of product concept and impact on symptoms of sub-health in a group of males

    PubMed Central

    2013-01-01

    Background A new dietary supplement, Fatigue Reviva™, has been recently developed to address issues related to amino acid depletion following illness or in conditions of sub-health where altered amino acid homeostasis has been associated with fatigue. Complex formulations of amino acids present significant challenges due to solubility and taste constraints. This initial study sets out to provide an initial appraisal of product palatability and to gather pilot evidence for efficacy. Methods Males reporting symptoms of sub-health were recruited on the basis of being free from any significant medical or psychological condition. Each participant took an amino acid based dietary supplement (Fatigue Reviva™) daily for 30 days. Comparisons were then made between pre- and post-supplement general health symptoms and urinary amino acid profiles. Results Seventeen men took part in the study. Following amino acid supplementation the total Chalder fatigue score improved significantly (mean ± SEM, 12.5 ± 0.9 versus 10.0 ± 1.0, P<0.03). When asked whether they thought that the supplement had improved their health, 65% of participants responded positively. A subgroup of participants reported gastrointestinal symptoms which were attributed to the supplement and which were believed to result from the component fructooligosaccharide. Analysis of urinary amino acids revealed significant alterations in the relative abundances of a number of amino acids after supplementation including an increase in valine, isoleucine and glutamic acid and reduced levels of glutamine and ornithine. Discriminant function analysis of the urinary amino acid data revealed significant differences between the pre- and post-supplement urine excretion profiles. Conclusions The results indicated that Fatigue Reviva™ was palatable and that 65% of the study group reported that they felt the product had improved their health. The product could provide an effective tool for the management of unexplained

  3. Self-Concept and Psychological Adjustment Differences Between Self-Identified Male Transexuals and Male Homosexuals

    ERIC Educational Resources Information Center

    Roback, Howard B.; And Others

    1977-01-01

    Self-concept and adjustment data from anatomical males seeking sexual reassignment surgery were compared with that from a male homosexual group. Findings indicated that the homosexual group had a better self-image and was better adjusted than the sex change group. (Author)

  4. Male pattern baldness

    MedlinePlus

    Alopecia in men; Baldness - male; Hair loss in men; Androgenetic alopecia ... Male pattern baldness is related to your genes and male sex hormones. It usually follows a pattern of receding hairline and ...

  5. The visible human male: a technical report.

    PubMed Central

    Spitzer, V; Ackerman, M J; Scherzinger, A L; Whitlock, D

    1996-01-01

    The National Library of Medicine's Visible Human Male data set consists of digital magnetic resonance (MR), computed tomography (CT), and anatomic images derived from a single male cadaver. The data set is 15 gigabytes in size and is available from the National Library of Medicine under a no-cost license agreement. The history of the Visible Human Male cadaver and the methods and technology to produce the data set are described. PMID:8653448

  6. Effect of endosulfan on male reproductive development.

    PubMed

    Saiyed, Habibullah; Dewan, Aruna; Bhatnagar, Vijay; Shenoy, Udyavar; Shenoy, Rathika; Rajmohan, Hirehall; Patel, Kumud; Kashyap, Rekha; Kulkarni, Pradip; Rajan, Bagalur; Lakkad, Bhadabhai

    2003-12-01

    There is experimental evidence of adverse effects of endosulfan on the male reproductive system, but there are no human data. Therefore, we undertook a study to examine the relationship between environmental endosulfan exposure and reproductive development in male children and adolescents. The study population was composed of 117 male schoolchildren (10-19 years of age) of a village situated at the foothills of cashew plantations, where endosulfan had been aerially sprayed for more than 20 years, and 90 comparable controls with no such exposure history. The study parameters included recording of clinical history, physical examination, sexual maturity rating (SMR) according to Tanner stages, and estimation of serum levels of testosterone, luteinizing hormone (LH), follicle-stimulating hormone, and endosulfan residues (70 study and 47 control subjects). Mean +/- SE serum endosulfan levels in the study group (7.47 +/- 1.19 ppb) were significantly higher (p < 0.001) than in controls (1.37 +/- 0.40 ppb). Multiple regression analysis showed that SMR scoring for development of pubic hair, testes, penis, and serum testosterone level was positively related to age and negatively related to aerial exposure to endosulfan (AEE; p < 0.01). Serum LH levels were significantly positively related to AEE after controlling for age (p < 0.01). The prevalence of congenital abnormalities related to testicular descent (congenital hydrocele, undescended testis, and congenital inguinal hernia) among study and controls subjects was 5.1% and 1.1%, respectively, but the differences were statistically nonsignificant. Our study results suggest that endosulfan exposure in male children may delay sexual maturity and interfere with sex hormone synthesis. Our study is limited by small sample size and nonparticipation. PMID:14644673

  7. Within species support for the expensive tissue hypothesis: a negative association between brain size and visceral fat storage in females of the Pacific seaweed pipefish.

    PubMed

    Tsuboi, Masahito; Shoji, Jun; Sogabe, Atsushi; Ahnesjö, Ingrid; Kolm, Niclas

    2016-02-01

    The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the high cost of brain development and maintenance is predicted to constrain adaptive brain size evolution (the expensive tissue hypothesis, ETH). Here, we test the ETH in a teleost fish with predominant female mating competition (reversed sex roles) and male pregnancy, the pacific seaweed pipefish Syngnathus schlegeli. The relative size of the brain and other energetically expensive organs (kidney, liver, heart, gut, visceral fat, and ovary/testis) was compared among three groups: pregnant males, nonpregnant males and egg producing females. Brood size in pregnant males was unrelated to brain size or the size of any other organ, whereas positive relationships were found between ovary size, kidney size, and liver size in females. Moreover, we found that the size of energetically expensive organs (brain, heart, gut, kidney, and liver) as well as the amount of visceral fat did not differ between pregnant and nonpregnant males. However, we found marked differences in relative size of the expensive organs between sexes. Females had larger liver and kidney than males, whereas males stored more visceral fat than females. Furthermore, in females we found a negative correlation between brain size and the amount of visceral fat, whereas in males, a positive trend between brain size and both liver and heart size was found. These results suggest that, while the majority of variation in the size of various expensive organs in this species likely reflects that individuals in good condition can afford to allocate resources to several organs, the cost of the expensive brain was visible in the visceral fat content of females, possibly due to the high costs associated with female egg production. PMID:26865955

  8. Measurements of benzene and formaldehyde in a medium sized urban environment. Indoor/outdoor health risk implications on special population groups.

    PubMed

    Pilidis, Georgios A; Karakitsios, Spyros P; Kassomenos, Pavlos A; Kazos, Elias A; Stalikas, Constantine D

    2009-03-01

    In the present study, the results of a measurement campaign aiming to assess cancer risk among two special groups of population: policemen and laboratory technicians exposed to the toxic substances, benzene and formaldehyde are presented. The exposure is compared to general population risk. The results show that policemen working outdoor (traffic regulation, patrol on foot or in vehicles, etc.) are exposed at a significantly higher benzene concentration (3-5 times) than the general population, while the exposure to carbonyls is in general lower. The laboratory technicians appear to be highly exposed to formaldehyde while no significant variation of benzene exposure in comparison to the general population is recorded. The assessment revealed that laboratory technicians and policemen run a 20% and 1% higher cancer risk respectively compared to the general population. Indoor working place air quality is more significant in assessing cancer risk in these two categories of professionals, due to the higher Inhalation Unit Risk (IUR) of formaldehyde compared to benzene. Since the origin of the danger to laboratory technicians is clear (use of chemicals necessary for the experiments), in policemen the presence of carbonyls in indoor air concentrations due to smoking or used materials constitute a danger equal to the exposure to traffic originated air pollutants. PMID:18386150

  9. Factor Analysis of the Modified Sexual Adjustment Questionnaire-Male

    PubMed Central

    Wilmoth, Margaret C.; Hanlon, Alexandra L.; Ng, Lit Soo; Bruner, Debra W.

    2015-01-01

    Background and Purpose The Sexual Adjustment Questionnaire (SAQ) is used in National Cancer Institute–sponsored clinical trials as an outcome measure for sexual functioning. The tool was revised to meet the needs for a clinically useful, theory-based outcome measure for use in both research and clinical settings. This report describes the modifications and validity testing of the modified Sexual Adjustment Questionnaire-Male (mSAQ-Male). Methods This secondary analysis of data from a large Radiation Therapy Oncology Group trial employed principal axis factor analytic techniques in estimating validity of the revised tool. The sample size was 686; most subjects were White, older than the age 60 years, and with a high school education and a Karnofsky performance scale (KPS) score of greater than 90. Results A 16-item, 3-factor solution resulted from the factor analysis. The mSAQ-Male was also found to be sensitive to changes in physical sexual functioning as measured by the KPS. Conclusion The mSAQ-Male is a valid self-report measure of sexuality that can be used clinically to detect changes in male sexual functioning. PMID:25255676

  10. Assessment of environmental factors affecting male fertility.

    PubMed

    Dixon, R L; Sherins, R J; Lee, I P

    1979-06-01

    ppm boron displayed a significant loss of germinal elements, although most of the Leydig and Sertoli cells appeared normal. Testicular atrophy was associated with a decrease in seminiferous tubular diameter and a marked reduction of spermatocytes and spermatogenic cells. These morphologic alterations were associated with a concomitant reduction of H, SDH, and LDH-X specific activities. In contrast, the specific activities of G3PDH and MDH were significantly elevated above control. The increase in these enzyme activities can be attributed to the relative enrichment of spermatogonial cells during the loss of spermatocytes and spermiogenic cells. Boron-induced male germinal aplasia was also associated with significantly elevated plasma FSH while plasma LH and testosterone levels were not significantly altered. Plasma testosterone levels were unaltered. Male fertility studies demonstrated that at the 500 ppm boron level, fertility was unaffected. However, at 1000 and 2000 ppm boron, male fertility was significantly reduced. Most effects were reversible within 5 weeks. However, the male group receiving 2000 ppm boron for 60 days remained sterile. There was no dose-related decrease in litter size or fetal death in utero. Therefore, the boron-induced infertility was apparently not due to a dominant lethal effect but rather to germinal aplasia. Boron appears toxic to spermatogenic cells at testicular concentrations of 6-8 ppm. PMID:446458

  11. 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;…

  12. Foraging competition in larger groups overrides harassment avoidance benefits in female reindeer (Rangifer tarandus).

    PubMed

    Uccheddu, Stefania; Body, Guillaume; Weladji, Robert B; Holand, Øystein; Nieminen, Mauri

    2015-11-01

    Male harassment toward females during the breeding season may have a negative effect on their reproductive success by disturbing their foraging activity, thereby inducing somatic costs. Accordingly, it is predicted that females will choose mates based on their ability to provide protection or will aggregate into large groups to dilute per capita harassment level. Conversely, increasing group size may also lead to a decrease in foraging activity by increasing foraging competition, but this effect has rarely been considered in mating tactic studies. This study examined the importance of two non-exclusive hypotheses in explaining the variations of the female activity budget during the breeding season: the male harassment hypothesis, and the female foraging competition hypothesis. We used focal observations of female activity from known mating groups collected during the breeding season from a long-term (15 years) study on reindeer Rangifer tarandus. We found that females were more disturbed (i.e., spent less time feeding) in the presence of young dominant males, and marginally disturbed in the presence of satellite males, which supports the male harassment hypothesis. We also found that female disturbance level increased with group size, being independent of the adult sex ratio. Consequently, these results rejected the dilution effect, but strongly supported the foraging competition hypothesis. This study therefore highlights a potential conflict in female behaviour. Indeed, any gains from harassment protection were negated by an increase of 6-7 females, since adult males lead larger groups than young males. PMID:26188521

  13. Body Size, Fecundity, and Sexual Size Dimorphism in the Neotropical Cricket Macroanaxipha macilenta (Saussure) (Orthoptera: Gryllidae).

    PubMed

    Cueva Del Castillo, R

    2015-04-01

    Body size is directly or indirectly correlated with fitness. Body size, which conveys maximal fitness, often differs between sexes. Sexual size dimorphism (SSD) evolves because body size tends to be related to reproductive success through different pathways in males and females. In general, female insects are larger than males, suggesting that natural selection for high female fecundity could be stronger than sexual selection in males. I assessed the role of body size and fecundity in SSD in the Neotropical cricket Macroanaxipha macilenta (Saussure). This species shows a SSD bias toward males. Females did not present a correlation between number of eggs and body size. Nonetheless, there were fluctuations in the number of eggs carried by females during the sampling period, and the size of females that were collected carrying eggs was larger than that of females collected with no eggs. Since mating induces vitellogenesis in some cricket species, differences in female body size might suggest male mate choice. Sexual selection in the body size of males of M. macilenta may possibly be stronger than the selection of female fecundity. Even so, no mating behavior was observed during the field observations, including audible male calling or courtship songs, yet males may produce ultrasonic calls due to their size. If female body size in M. macilenta is not directly related to fecundity, the lack of a correlated response to selection on female body size could represent an alternate evolutionary pathway in the evolution of body size and SSD in insects. PMID:26013128

  14. Lisping and male homosexuality.

    PubMed

    Van Borsel, John; Van de Putte, Anneleen

    2014-08-01

    The present study examined the popular stereotype that gay men lisp by evaluating to what extent listeners associated dental or frontal articulation/lisping with gayness. Fifteen heterosexual males and 15 heterosexual females listened to 275 samples of read speech and judged the sexual orientation of the speakers. A total of 175 of the samples were of homosexual men, 74 (42.3 %) of which had been identified with lisping in a previous study; 100 were of heterosexual men, 18 (18 %) of which had been identified with lisping previously. Based on the ratings of the listeners of the present study, lisping speakers were significantly more often judged to be homosexual. This was true for the group as a whole as well as for the subgroup of homosexual and heterosexual men separately. Furthermore, there was no significant gender difference with respect to associating lisping with gayness. Male and female judges associated lisping with gayness to a similar degree. Additional analysis showed that overall 56.2 % of the time the judges were correct in their judgment of the speakers' sexual orientation. The results of this study confirmed previous preliminary findings that suggested that frontal or dental articulation/lisping is a feature that listeners associate with gayness. The reason for this association remains to be clarified. PMID:24578106

  15. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

    PubMed Central

    King, Richard B.

    2016-01-01

    Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID

  16. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size.

    PubMed

    King, Richard B; Stanford, Kristin M; Jones, Peter C; Bekker, Kent

    2016-01-01

    Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631-820 mm snout-vent length in males and from 835-1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID:26730712

  17. Courtship Sounds Advertise Species Identity and Male Quality in Sympatric Pomatoschistus spp. Gobies

    PubMed Central

    Pedroso, Silvia S.; Barber, Iain; Svensson, Ola; Fonseca, Paulo J.; Amorim, Maria Clara P.

    2013-01-01

    Acoustic signals can encode crucial information about species identity and individual quality. We recorded and compared male courtship drum sounds of the sand goby Pomatoschistus minutus and the painted goby P. pictus and examined if they can function in species recognition within sympatric populations. We also examined which acoustic features are related to male quality and the factors that affect female courtship in the sand goby, to determine whether vocalisations potentially play a role in mate assessment. Drums produced by the painted goby showed significantly higher dominant frequencies, higher sound pulse repetition rates and longer intervals between sounds than those of the sand goby. In the sand goby, male quality was predicted by visual and acoustic courtship signals. Regression analyses showed that sound amplitude was a good predictor of male length, whereas the duration of nest behaviour and active calling rate (i.e. excluding silent periods) were good predictors of male condition factor and fat reserves respectively. In addition, the level of female courtship was predicted by male nest behaviour. The results suggest that the frequency and temporal patterns of sounds can encode species identity, whereas sound amplitude and calling activity reflects male size and fat reserves. Visual courtship duration (nest-related behaviour) also seems relevant to mate choice, since it reflects male condition and is related to female courtship. Our work suggests that acoustic communication can contribute to mate choice in the sand goby group, and invites further study. PMID:23755129

  18. Courtship sounds advertise species identity and male quality in sympatric Pomatoschistus spp. gobies.

    PubMed

    Pedroso, Silvia S; Barber, Iain; Svensson, Ola; Fonseca, Paulo J; Amorim, Maria Clara P

    2013-01-01

    Acoustic signals can encode crucial information about species identity and individual quality. We recorded and compared male courtship drum sounds of the sand goby Pomatoschistus minutus and the painted goby P. pictus and examined if they can function in species recognition within sympatric populations. We also examined which acoustic features are related to male quality and the factors that affect female courtship in the sand goby, to determine whether vocalisations potentially play a role in mate assessment. Drums produced by the painted goby showed significantly higher dominant frequencies, higher sound pulse repetition rates and longer intervals between sounds than those of the sand goby. In the sand goby, male quality was predicted by visual and acoustic courtship signals. Regression analyses showed that sound amplitude was a good predictor of male length, whereas the duration of nest behaviour and active calling rate (i.e. excluding silent periods) were good predictors of male condition factor and fat reserves respectively. In addition, the level of female courtship was predicted by male nest behaviour. The results suggest that the frequency and temporal patterns of sounds can encode species identity, whereas sound amplitude and calling activity reflects male size and fat reserves. Visual courtship duration (nest-related behaviour) also seems relevant to mate choice, since it reflects male condition and is related to female courtship. Our work suggests that acoustic communication can contribute to mate choice in the sand goby group, and invites further study. PMID:23755129

  19. Rogue Males? Approaches to Study and Academic Performance of Male Psychology Students

    ERIC Educational Resources Information Center

    Sanders, Lalage; Sander, Paul; Mercer, Jenny

    2009-01-01

    This three-year longitudinal study explored the approach to study and academic performance of a group of male psychology undergraduates. In induction week, 112 new psychology students completed the survey. Later in the year, some of the males were interviewed in small groups. Performance was measured from marks at the end of Years 1 and 3. In Year…

  20. Does Male Care, Provided to Immature Individuals, Influence Immature Fitness in Rhesus Macaques?

    PubMed Central

    Langos, Doreen; Kulik, Lars; Ruiz-Lambides, Angelina; Widdig, Anja

    2015-01-01

    Among many mammals, maternal care strongly impacts infant survival; however, less is known about whether adult males also affect infant fitness. Paternal care is expected when providing care enhances offspring survival and reproduction, which likewise increases fathers’ fitness. Males might also care for unrelated immature individuals to increase their mating probability with the immature individuals’ mothers. Studies in multimale primate groups showed that sires enhance food access for offspring and provide protection in conflicts. Furthermore, fathers’ presence during infancy has been suggested to accelerate offspring sexual maturation. However, no study has yet directly linked the degree of father-offspring bonds to offspring fitness in primates. We previously reported father-offspring affiliation in rhesus macaques, pronounced during early infancy and independent of mothers’ presence. The present study aims at investigating whether affiliation with fathers or other males affects proxies of immature fitness (body mass gain, body fat and testis size). First, we combined behavioral, genetic and morphometric data from 55 subjects of one group. Second, using demographic and genetic data, we investigated for 92 individuals of the population whether mother- and father-offspring co-residence during immaturity influenced offspring lifetime reproductive success (LRS). Our results show that focal rank and higher amounts of affiliation with high-ranking males during infancy tend to positively impact body mass gain of female, but not male focal animals. In contrast, body mass gain of male focal individuals, but not females’, appeared to be higher when affiliation of male immature individuals was evenly distributed across their adult male partners. Moreover, we found mothers’, but not fathers’, presence during immaturity to predict offspring LRS. Our results suggest that male-immature affiliation, but not father-offspring co-residence, potentially impacts

  1. Male motion coordination in anopheline mating swarms

    NASA Astrophysics Data System (ADS)

    Shishika, Daigo; Manoukis, Nicholas C.; Butail, Sachit; Paley, Derek A.

    2014-09-01

    The Anopheles gambiae species complex comprises the primary vectors of malaria in much of sub-Saharan Africa. Most of the mating in these species occurs in swarms composed almost entirely of males. Intermittent, organized patterns in such swarms have been observed, but a detailed description of male-male interactions has not previously been available. We identify frequent, time-varying interactions characterized by periods of parallel flight in data from 8 swarms of Anopheles gambiae and 3 swarms of Anopheles coluzzii filmed in 2010 and 2011 in the village of Donéguébogou, Mali. We use the cross correlation of flight direction to quantify these interactions and to induce interaction graphs, which show that males form synchronized subgroups whose size and membership change rapidly. A swarming model with damped springs between each male and the swarm centroid shows good agreement with the correlation data, provided that local interactions represented by damping of relative velocity between males are included.

  2. Impact of psychosocial stress on pineal structure of male gerbils (Meriones unguiculatus, cricetidae).

    PubMed

    Heinzeller, T

    1985-01-01

    Stress responses were investigated in 5-month-old male gerbils. Breeders having no pubescent litters served as controls. The first experimental group never left their parents' cage and were thereby fought by higher-ranking males; the second and third groups were stressed for a week by four daily 1-minute encounters with trained fighters, the second group during daytime, the third during the dark period. The first and second groups developed signs of gonadal regression, the third did not. The adrenals of the first group weighed the same as those of controls; the adrenals of both other groups were increased in weight. In the adrenal medulla of all experimental groups, a large number of cells were densely packed with noradrenaline-containing vesicles. In each experimental group the pineal changes included a remarkable decrease in nuclear size of pinealocytes, an increased number of colloidal cysts, and a reduction of that portion of the plasmalemma that is lined by subsurface cisterns. All these changes are interpreted in terms of pineal activation, as are the increased number of membrane whirls found in the first group. The third group exhibited an additional decrease in the size of mitochondria and in the number of "synaptic" structures. This finding and the day-night differences in the gonadal response indicate that stress interferes with the metabolic cyclicity of the pineal gland. However, it remains indiscernible whether the pineal stress reaction signals a general activation of the gland or a change in it's temporal activity patterns. PMID:3831304

  3. Recruiting and Retaining Male Special Education Teachers

    ERIC Educational Resources Information Center

    Rice, Craig J.; Goessling, Deborah Peters

    2005-01-01

    The percentage of male students who complete an undergraduate degree in the field of special education continues to be much lower than that of female graduates. Low status, low salaries, the perception of teaching as women's work, potential complaints of child abuse and sexual harassment, and a lack of male peer groups factor into this low…

  4. The Sexual Stereotype of the Black Male.

    ERIC Educational Resources Information Center

    Davis, Gary L.; Cross, Herbert J.

    This paper presents the results of a study to examine the existence of sexual stereotyping of black males by white college students. Subjects were 180 male and 180 female white undergraduates; they were tested in sexually segregated groups. Each read one of three types of pornographic stories (hard-core, erotic realism, or sexual fantasy). The…

  5. Male pattern baldness (image)

    MedlinePlus

    Male pattern baldness is a sex-linked characteristic that is passed from mother to child. A man can more accurately predict his chances of developing male pattern baldness by observing his mother's father than by looking ...

  6. Male pattern baldness (image)

    MedlinePlus

    Male pattern baldness is a sex-linked characteristic that is passed from mother to child. A man can more accurately predict his chances of developing male pattern baldness by observing his mother's father than ...

  7. Class Size.

    ERIC Educational Resources Information Center

    Underwood, Siobhan; Lumsden, Linda S.

    1994-01-01

    The items featured in this annotated bibliography touch on several aspects of the multifaceted class-size debate. Allen Odden reviews the literature and contends that class-size reduction should be used "sparingly and strategically." C. M. Achilles and colleagues examines two different class-size situations and find student test performance in the…

  8. Class Size.

    ERIC Educational Resources Information Center

    Johnston, Holly R.

    Exploring the class-size issue, this paper focuses on the primary grades and asks questions such as "does a reduction in class size promote an increase in academic achievement?" and "how substantial does the reduction in numbers have to be in order for a significant increase to occur?" The paper surveys debates on class size and the social factors…

  9. Trade-off between male and female allocation in the simultaneously hermaphroditic flatworm Macrostomum sp.

    PubMed

    Schärer, L; Sandner, P; Michiels, N K

    2005-03-01

    Sex allocation theory for simultaneous hermaphrodites assumes a direct trade-off between the allocation of resources to the male and female reproductive functions. Empirical support for this basic assumption is scarce, possibly because studies rarely control for variation in individual reproductive resource budgets. Such variation, which can have environmental or genetic sources, can generate a positive relationship between male and female investment and can thus obscure the trade-off. In this study on the hermaphroditic flatworm Macrostomum sp. we tried to control for budget effects by restricting food availability in a standardized way and by using an inbred line. We then manipulated mating group size in a two-way design (two group sizes x two enclosure sizes) in order to induce phenotypic variation in male allocation, and expected to find an opposing correlated response in female allocation. The results suggest that we only managed to control the budget effects under some conditions. Under these the sex allocation trade-off emerged. Under the other conditions we found a strongly positive correlation between male and female allocation. We discuss possible causes for the observed differences. PMID:15715845

  10. Disordered eating in male athletes: a meta-analysis.

    PubMed

    Chapman, James; Woodman, Tim

    2016-01-01

    We examined the propensity for male athletes to exhibit symptoms of disordered eating. Using meta-analytic techniques, we examined overall effect size, individual effect sizes for specific sport types, standard of athletic competition and diagnostic tools from 31 studies. When all studies were considered as a homogeneous group, male athletes did not have symptoms of disordered eating that were significantly different from non-athletic controls. However, significant moderator effects emerged for sport type and measurement: (a) wrestling reported a greater incidence of disordered eating; and (b) studies that reported data from the Eating Attitudes Test yielded a significantly greater incidence of disordered eating in male athletes compared to non-athletes. Although some sports seem to present a higher risk of disordered eating compared to others, the effects are weak and heterogeneous. We make suggestions for the development of the research area, which has been severely hampered by the diagnostic tools that have been available for the study of men. PMID:25916949

  11. Small Group Research

    ERIC Educational Resources Information Center

    McGrath, Joseph E.

    1978-01-01

    Summarizes research on small group processes by giving a comprehensive account of the types of variables primarily studied in the laboratory. These include group structure, group composition, group size, and group relations. Considers effects of power, leadership, conformity to social norms, and role relationships. (Author/AV)

  12. A further cost for the sicker sex? Evidence for male-biased parasite-induced vulnerability to predation.

    PubMed

    Stephenson, Jessica F; Kinsella, Cormac; Cable, Joanne; van Oosterhout, Cock

    2016-04-01

    Males are typically the sicker sex. Data from multiple taxa indicate that they are more likely to be infected with parasites, and are less "tolerant," or less able to mitigate the fitness costs of a given infection, than females. One cost of infection for many animals is an increased probability of being captured by a predator. A clear, hitherto untested, prediction is therefore that this parasite-induced vulnerability to predation is more pronounced among males than females. We tested this prediction in the sexually size dimorphic guppy, Poecilia reticulata, in which females are typically larger than males. We either sham or experimentally infected guppies with Gyrodactylus turnbulli, elicited their escape response using an established protocol and measured the distance they covered during 60 ms. To discriminate between the effects of body size and those of other inherent sex differences, we size-matched fish across treatment groups. Infection with G. turnbulli reduced the distance covered during the escape response of small adults by 20.1%, whereas that of large fish was unaffected. This result implies that parasite-induced vulnerability to predation is male-biased in the wild: although there was no difference in escape response between our experimentally size-matched groups of males and females, males are significantly smaller across natural guppy populations. These results are consistent with Bateman's principle for immunity: Natural selection for larger body sizes and longevity in females seems to have resulted in the evolution of increased infection tolerance. We discuss the potential implications of sex- and size-biased parasite-induced vulnerability to predation for the evolutionary ecology of this host-parasite interaction in natural communities. PMID:27066240

  13. Conditioned same-sex partner preference in male rats is facilitated by oxytocin and dopamine: effect on sexually dimorphic brain nuclei.

    PubMed

    Triana-Del Rio, Rodrigo; Tecamachaltzi-Silvarán, Miriam B; Díaz-Estrada, Victor X; Herrera-Covarrubias, Deissy; Corona-Morales, Aleph A; Pfaus, James G; Coria-Avila, Genaro A

    2015-04-15

    Conditioned same-sex partner preference can develop in male rats that undergo cohabitation under the effects of quinpirole (QNP, D2 agonist). Herein, we assessed the development of conditioned same-sex social/sexual preference in males that received either nothing, saline, QNP, oxytocin (OT), or QNP+OT during cohabitation with another male (+) or single-caged (-). This resulted in the following groups: (1) Intact-, (2) Saline+, (3) QNP-, (4) OT-, (5) QNP+, (6) OT+ and (7) QNP/OT+. Cohabitation occurred during 24h in a clean cage with a male partner that bore almond scent on the back as conditioned stimulus. This was repeated every 4 days for a total of three trials. Social and sexual preference were assessed four days after the last conditioning trial in a drug-free test in which experimental males chose between the scented familiar male and a novel sexually receptive female. Results showed that males from groups Intact-, Saline+, QNP- and OT- displayed a clear preference for the female (opposite-sex), whereas groups QNP+, OT+ and QNP/OT+ displayed socio/sexual preference for the male partner (same-sex). In Experiment 2, the brains were processed for Nissl dye and the area size of two sexually dimorphic nuclei (SDN-POA and SON) was compared between groups. Males from groups OT-, OT+ and QNP/OT+ expressed a smaller SDN-POA and groups QNP+ and QNP/OT+ expressed a larger SON. Accordingly, conditioned same-sex social/sexual partner preference can develop during cohabitation under enhanced D2 or OT activity but such preference does not depend on the area size of those sexually dimorphic nuclei. PMID:25601575

  14. Two New Cave-Dwelling Species of the Short-Tailed Whipscorpion Genus Rowlandius (Arachnida: Schizomida: Hubbardiidae) from Northeastern Brazil, with Comments on Male Dimorphism

    PubMed Central

    Santos, Adalberto J.; Ferreira, Rodrigo Lopes; Buzatto, Bruno A.

    2013-01-01

    Two new species of the arachnid order Schizomida, Rowlandius ubajara sp.nov. and Rowlandius potiguar sp.nov., are described based on both male and female specimens collected in caves from northeastern Brazil. Rowlandius ubajara is known only from the Ubajara Cave, in the state of Ceará; R. potiguar is recorded from 20 caves of the Apodi Limestone Group, in the state of Rio Grande do Norte. A remarkable dimorphism in male pedipalp length is described and analyzed in R. potiguar. The distribution of male pedipalp length is clearly bimodal in the species, but the two male morphs (homeomorphic and heteromorphic) present some overlap in the sizes of this structure. Moreover, males show a steeper allometry in pedipalp length than females, indicating that this trait is under a different selective regime in males and in females. PMID:23723989

  15. A group's physical attractiveness is greater than the average attractiveness of its members: the group attractiveness effect.

    PubMed

    van Osch, Yvette; Blanken, Irene; Meijs, Maartje H J; van Wolferen, Job

    2015-04-01

    We tested whether the perceived physical attractiveness of a group is greater than the average attractiveness of its members. In nine studies, we find evidence for the so-called group attractiveness effect (GA-effect), using female, male, and mixed-gender groups, indicating that group impressions of physical attractiveness are more positive than the average ratings of the group members. A meta-analysis on 33 comparisons reveals that the effect is medium to large (Cohen's d = 0.60) and moderated by group size. We explored two explanations for the GA-effect: (a) selective attention to attractive group members, and (b) the Gestalt principle of similarity. The results of our studies are in favor of the selective attention account: People selectively attend to the most attractive members of a group and their attractiveness has a greater influence on the evaluation of the group. PMID:25733515

  16. Induction of sexual activity in lactating anovulatory female goats using male goats treated only with artificially long days.

    PubMed

    Delgadillo, J A; Flores, J A; Véliz, F G; Hernández, H F; Duarte, G; Vielma, J; Poindron, P; Chemineau, P; Malpaux, B

    2002-11-01

    Two experiments were conducted to determine the response of Creole male goats treated with long days and melatonin implants, and the response of the anovulatory does to male effect using males treated only with artificially long days. All animals were allocated to open sheds. In Exp. 1, one group of males was under natural photoperiod (CG; n = 7); the second group was submitted to 2.5 mo of long days followed by the insertion of two s.c. melatonin implants (LD+MEL; n = 7); the third group was subjected only to 2.5 mo of long days (LD; n = 7). Testicular weight was measured every 2 wk. Plasma testosterone concentrations were determined weekly. A treatment x time interaction was detected (P < 0.001) for testicular weight and plasma testosterone concentration. In the LD+MEL and LD groups, testicular