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Sample records for adult sex ratios

  1. Breeding Sex Ratios in Adult Leatherback Turtles (Dermochelys coriacea) May Compensate for Female-Biased Hatchling Sex Ratios

    PubMed Central

    Stewart, Kelly R.; Dutton, Peter H.

    2014-01-01

    For vertebrates with temperature-dependent sex determination, primary (or hatchling) sex ratios are often skewed, an issue of particular relevance to concerns over effects of climate change on populations. However, the ratio of breeding males to females, or the operational sex ratio (OSR), is important to understand because it has consequences for population demographics and determines the capacity of a species to persist. The OSR also affects mating behaviors and mate choice, depending on the more abundant sex. For sea turtles, hatchling and juvenile sex ratios are generally female-biased, and with warming nesting beach temperatures, there is concern that populations may become feminized. Our purpose was to evaluate the breeding sex ratio for leatherback turtles at a nesting beach in St. Croix, USVI. In 2010, we sampled nesting females and later sampled their hatchlings as they emerged from nests. Total genomic DNA was extracted and all individuals were genotyped using 6 polymorphic microsatellite markers. We genotyped 662 hatchlings from 58 females, matching 55 females conclusively to their nests. Of the 55, 42 females mated with one male each, 9 mated with 2 males each and 4 mated with at least 3 males each, for a multiple paternity rate of 23.6%. Using GERUD1.0, we reconstructed parental genotypes, identifying 47 different males and 46 females for an estimated breeding sex ratio of 1.02 males for every female. Thus we demonstrate that there are as many actively breeding males as females in this population. Concerns about female-biased adult sex ratios may be premature, and mate choice or competition may play more of a role in sea turtle reproduction than previously thought. We recommend monitoring breeding sex ratios in the future to allow the integration of this demographic parameter in population models. PMID:24505403

  2. Sex-biased survival predicts adult sex ratio variation in wild birds

    PubMed Central

    Székely, Tamás; Liker, András; Freckleton, Robert P.; Fichtel, Claudia; Kappeler, Peter M.

    2014-01-01

    Adult sex ratio (ASR) is a central concept in population demography and breeding system evolution, and has implications for population viability and biodiversity conservation. ASR exhibits immense interspecific variation in wild populations, although the causes of this variation have remained elusive. Using phylogenetic analyses of 187 avian species from 59 families, we show that neither hatching sex ratios nor fledging sex ratios correlate with ASR. However, sex-biased adult mortality is a significant predictor of ASR, and this relationship is robust to 100 alternative phylogenetic hypotheses, and potential ecological and life-history confounds. A significant component of adult mortality bias is sexual selection acting on males, whereas increased reproductive output predicts higher mortality in females. These results provide the most comprehensive insights into ASR variation to date, and suggest that ASR is an outcome of selective processes operating differentially on adult males and females. Therefore, revealing the causes of ASR variation in wild populations is essential for understanding breeding systems and population dynamics. PMID:24966308

  3. Sex-biased survival predicts adult sex ratio variation in wild birds.

    PubMed

    Székely, Tamás; Liker, András; Freckleton, Robert P; Fichtel, Claudia; Kappeler, Peter M

    2014-08-01

    Adult sex ratio (ASR) is a central concept in population demography and breeding system evolution, and has implications for population viability and biodiversity conservation. ASR exhibits immense interspecific variation in wild populations, although the causes of this variation have remained elusive. Using phylogenetic analyses of 187 avian species from 59 families, we show that neither hatching sex ratios nor fledging sex ratios correlate with ASR. However, sex-biased adult mortality is a significant predictor of ASR, and this relationship is robust to 100 alternative phylogenetic hypotheses, and potential ecological and life-history confounds. A significant component of adult mortality bias is sexual selection acting on males, whereas increased reproductive output predicts higher mortality in females. These results provide the most comprehensive insights into ASR variation to date, and suggest that ASR is an outcome of selective processes operating differentially on adult males and females. Therefore, revealing the causes of ASR variation in wild populations is essential for understanding breeding systems and population dynamics. PMID:24966308

  4. The genetic sex-determination system predicts adult sex ratios in tetrapods.

    PubMed

    Pipoly, Ivett; Bókony, Veronika; Kirkpatrick, Mark; Donald, Paul F; Székely, Tamás; Liker, András

    2015-11-01

    The adult sex ratio (ASR) has critical effects on behaviour, ecology and population dynamics, but the causes of variation in ASRs are unclear. Here we assess whether the type of genetic sex determination influences the ASR using data from 344 species in 117 families of tetrapods. We show that taxa with female heterogamety have a significantly more male-biased ASR (proportion of males: 0.55 ± 0.01 (mean ± s.e.m.)) than taxa with male heterogamety (0.43 ± 0.01). The genetic sex-determination system explains 24% of interspecific variation in ASRs in amphibians and 36% in reptiles. We consider several genetic factors that could contribute to this pattern, including meiotic drive and sex-linked deleterious mutations, but further work is needed to quantify their effects. Regardless of the mechanism, the effects of the genetic sex-determination system on the adult sex ratio are likely to have profound effects on the demography and social behaviour of tetrapods. PMID:26444239

  5. A method for estimating fall adult sex ratios from production and survival data

    USGS Publications Warehouse

    Wight, H.M.; Heath, R.G.; Geis, A.D.

    1965-01-01

    This paper presents a method of utilizing data relating to the production and survival of a bird population to estimate a basic fall adult sex ratio. This basic adult sex ratio is an average value derived from average production and survival rates. It is an estimate of the average sex ratio about which the fall adult ratios will fluctuate according to annual variations in production and survival. The basic fall adult sex ratio has been calculated as an asymptotic value which is the limit of an infinite series wherein average population characteristics are used as constants. Graphs are provided that allow the determination of basic sex ratios from production and survival data of a population. Where the respective asymptote has been determined, it may be possible to estimate various production and survival rates by use of variations of the formula for estimating the asymptote.

  6. High Adult Sex Ratios and Risky Sexual Behaviors: A Systematic Review

    PubMed Central

    Bien, Cedric H.; Cai, Yong; Emch, Michael E.; Parish, William; Tucker, Joseph D.

    2013-01-01

    Background Thirty-four countries worldwide have abnormally high sex ratios (>102 men per 100 women), resulting in over 100 million missing women. Widespread sex selective abortion, neglect of young girls leading to premature mortality, and gendered migration have contributed to these persistent and increasing distortions. Abnormally high adult sex ratios in communities may drive sexually transmitted disease (STD) spread where women are missing and men cannot find stable partners. We systematically reviewed evidence on the association between high community sex ratios and individual sexual behaviors. Methods and Findings Seven databases (PubMed, Web of Science, Embase, Scopus, The Cochrane Database of Systematic Reviews, Sociological Abstracts, and PopLINE) were searched without restrictions on time or location. We followed PRISMA guidelines and evaluated quality according to STROBE criteria. 1093 citations were identified and six studies describing 57,054 individuals were included for review. All six studies showed an association between high community sex ratios and individual sexual risk behaviors. In high sex ratio communities, women were more likely to have multiple sex partners and men were more likely to delay first sexual intercourse and purchase sex. Only two studies included STD outcomes. Conclusions High community sex ratios were associated with increased individual sexual risk behavior among both men and women. However, none of the studies examined unprotected sex or appropriately adjusted for gendered migration. Further studies are needed to understand the effect of community sex ratios on sexual health and to inform comprehensive STD control interventions. PMID:23967223

  7. Sex-Ratio and Gender Differences in Depression in an Unselected Adult Population.

    ERIC Educational Resources Information Center

    Baumgart, E. P.; Oliver, J. M.

    1981-01-01

    Neither sex-ratio nor gender differences in depression were found in adult sample, similar to pattern found among university students. No demographic variable was correlated significantly with depression. Suggests results may be due to the elimination of face-to-face interviews, which expose males to greater negative repercussions for exhibiting…

  8. Environmental factors influencing adult sex ratio in Poecilia reticulata: laboratory experiments.

    PubMed

    McKellar, A E; Hendry, A P

    2011-10-01

    The potential causes of adult sex ratio variation in guppies Poecilia reticulata were tested in laboratory experiments that evaluated the mortality rates of male and female P. reticulata exposed to potential predators (Hart's rivulus Rivulus hartii and freshwater prawns Macrobrachium crenulatum) and to different resource levels. Poecilia reticulata mortality increased in the presence of R. hartii and M. crenulatum, and low resource levels had an effect on mortality only in the presence of M. crenulatum. Rivulus hartii preyed more often on male than on female P. reticulata, and this sex-biased predation was not simply the result of males being smaller than females. In contrast, no sex-biased mortality was attributable to M. crenulatum or low resource levels. PMID:21967582

  9. Divorce and infidelity are associated with skewed adult sex ratios in birds.

    PubMed

    Liker, András; Freckleton, Robert P; Székely, Tamás

    2014-04-14

    Adult sex ratio (ASR) is a fundamental concept in population demography, and recent theory suggests that ASR plays a central role in social behavior, mating systems, and parental care. Unbalanced ASRs are predicted to influence pair-bond and mating behavior, since the rarer sex in the population has more potential partners to mate with than the more common sex. Here we use phylogenetic comparative analyses to test whether ASR is related to three major aspects of mating behavior: divorce, social polygamy, and pair-bond infidelity. ASR is strongly correlated with long-term pair bonds, since the divorce rate is higher in species with a female-biased sex ratio, indicating that mate change by pair members and/or breaking of pair bonds by unmated individuals is more frequent when females outnumber males. Short-term pair bonds are also associated with unbalanced ASRs: males are more commonly polygamous when females outnumber males, and conversely, females are more polygamous when males outnumber females. Furthermore, infidelity increases with male-biased ASR in socially monogamous birds, suggesting that male coercion and/or female willingness to cheat the partner are facilitated by male-biased ASR. Our results provide the first comprehensive support for the proposition that ASR influences multiple aspects of pair-bond and mating behavior in wild populations. PMID:24656831

  10. Prenatal sex hormones, digit ratio, and face shape in adult males

    PubMed Central

    Weinberg, S. M.; Parsons, T. E.; Raffensperger, Z. D.; Marazita, M. L.

    2014-01-01

    Objectives Several reports have demonstrated a relationship between second to fourth digit ratio (2D:4D) and facial shape, suggesting that prenatal sex hormones play a role in the development of the craniofacial complex. Using 3D surface imaging and geometric morphometrics, we test the hypothesis that decreased digit ratio (indicative of increased prenatal androgen exposure) is associated with a more masculine facial phenotype. Methods 3D facial surface images and digit measures were collected on a sample of 151 adult males. Facial landmarks collected from the images were aligned by Procrustes superimposition and the resulting shape coordinates regressed on 2D:4D. Variations in facial shape related to 2D:4D were visualized with deformable surface warps. Results A significant statistical relationship was observed between facial shape variation and 2D:4D (p = 0.0084). Lower 2D:4D ratio in adult males was associated with increased facial width relative to height, increased mandibular prognathism, greater nasal projection, and increased upper and lower lip projection. Conclusions A statistical relationship between 2D:4D and facial shape in adult males was observed. Faces tended to look more masculine as 2D:4D decreased, suggesting a biologically plausible link between prenatal androgen exposure and the development of male facial characteristics. PMID:25257381

  11. Does the timing of attainment of maturity influence sexual size dimorphism and adult sex ratio in turtles?

    USGS Publications Warehouse

    Lovich, Jeffrey E.; Gibbons, J. Whitfield; Agha, Mickey

    2014-01-01

    The attainment of sexual maturity has been shown to affect measures of sexual size dimorphism (SSD) and adult sex ratios in several groups of vertebrates. Using data for turtles, we tested the model that sex ratios are expected to be male-biased when females are larger than males and female-biased when males are larger than females because of the relationship of each with the attainment of maturity. Our model is based on the premise that the earlier-maturing sex remains smaller, on average throughout life, and predominates numerically unless the sexes are strongly affected by differential mortality, differential emigration, and immigration, or biased primary sex ratios. Based on data for 24 species in seven families, SSD and sex ratios were significantly negatively correlated for most analyses, even after the effect of phylogenetic bias was removed. The analyses provide support for the model that SSD and adult sex ratios are correlated in turtles as a result of simultaneous correlation of each with sexual differences in attainment of maturity (bimaturism). Environmental sex determination provides a possible mechanism for the phenomenon in turtles and some other organisms.

  12. Persistence of an extreme male-biased adult sex ratio in a natural population of polyandrous bird.

    PubMed

    Kosztolányi, A; Barta, Z; Küpper, C; Székely, T

    2011-08-01

    In a number of insects, fishes and birds, the conventional sex roles are reversed: males are the main care provider, whereas females focus on matings. The reversal of typical sex roles is an evolutionary puzzle, because it challenges the foundations of sex roles, sexual selection and parental investment theory. Recent theoretical models predict that biased parental care may be a response to biased adult sex ratios (ASRs). However, estimating ASR is challenging in natural populations, because males and females often have different detectabilities. Here, we use demographic modelling with field data from 2101 individuals, including 579 molecularly sexed offspring, to provide evidence that ASR is strongly male biased in a polyandrous bird with male-biased care. The model predicts 6.1 times more adult males than females (ASR=0.860, proportion of males) in the Kentish plover Charadrius alexandrinus. The extreme male bias is consistent between years and concordant with experimental results showing strongly biased mating opportunity towards females. Based on these results, we conjecture that parental sex-role reversal may occur in populations that exhibit extreme male-biased ASR. PMID:21749544

  13. Sex Ratio and Body Mass of Adult Herbivorous Beetles Depend on Time of Occurrence and Light Conditions

    PubMed Central

    Łukowski, Adrian; Mąderek, Ewa; Giertych, Marian J.; Karolewski, Piotr

    2015-01-01

    Body mass and sex ratio (F/M) of folivorous insects are easily measured parameters that are commonly used to assess the effect of food quality, living conditions, and preferences on the selection of favourable sites for offspring. A study was conducted on the polyphagous beetle, Gonioctena quinquepunctata (a pest of the native Prunus padus and alien P. serotina) and on the monophagous beetle, Altica brevicollis coryletorum (a pest of Corylus avellana). Both species have a similar life cycle with emergence of current-year adults in summer, and reproduction of 1-year-old insects in spring. A. brevicollis coryletorum feeds primarily on sunlit shrubs, while G. quinquepunctata prefers shaded leaves. The present study assessed the effect of time of occurrence (insect age) on body mass in both sexes and on the sex ratio F/M, taking into account the influence of light conditions associated with their favoured food source (sunlit vs. shaded leaves). We hypothesized that a change in body mass in current-year insects would be determined by the amount of consumed food, while the sex ratio would be stable, when in 1-year-old insects females would die shortly after oviposition, while males would be active for a prolonged time. Results confirmed the hypothesis that changes in mass of current-year beetles was determined by the amount of food intake. We also found that in spring, unfertilized females coexist with fertilized ones and that the latter females live for some time after oviposition; resulting in fluctuations of the mean mass for females. In both species, 1-year-old beetles were heavier than current-year. The preference of A. brevicollis coryletorum for sunlit leaves results in a higher body weight than in G. quinquepunctata in both seasons. The data are consistent and indicate seasonal fluctuations in body mass and changes in the sex ratio in 1-year-old beetles, due to the entrance into their reproductive period. PMID:26657564

  14. Sex Ratio and Body Mass of Adult Herbivorous Beetles Depend on Time of Occurrence and Light Conditions.

    PubMed

    Łukowski, Adrian; Mąderek, Ewa; Giertych, Marian J; Karolewski, Piotr

    2015-01-01

    Body mass and sex ratio (F/M) of folivorous insects are easily measured parameters that are commonly used to assess the effect of food quality, living conditions, and preferences on the selection of favourable sites for offspring. A study was conducted on the polyphagous beetle, Gonioctenaquinquepunctata (a pest of the native Prunus padus and alien P. serotina) and on the monophagous beetle, Alticabrevicollis coryletorum (a pest of Corylus avellana). Both species have a similar life cycle with emergence of current-year adults in summer, and reproduction of 1-year-old insects in spring. A. brevicollis coryletorum feeds primarily on sunlit shrubs, while G. quinquepunctata prefers shaded leaves. The present study assessed the effect of time of occurrence(insect age) on body mass in both sexes and on the sex ratio F/M, taking into account the influence of light conditions associated with their favoured food source (sunlit vs. shaded leaves). We hypothesized that a change in body mass in current-year insects would be determined by the amount of consumed food, while the sex ratio would be stable, when in 1-year-old insects females would die shortly after oviposition, while males would be active for a prolonged time. Results confirmed the hypothesis that changes in mass of current-year beetles was determined by the amount of food intake. We also found that in spring, unfertilized females coexist with fertilized ones and that the latter females live for some time after oviposition; resulting in fluctuations of the mean mass for females. In both species, 1-year-old beetles were heavier than current-year. The preference of A. brevicollis coryletorum for sunlit leaves results in a higher body weight than in G. quinquepunctata in both seasons. The data are consistent and indicate seasonal fluctuations in body mass and changes in the sex ratio in 1-year-old beetles, due to the entrance into their reproductive period. PMID:26657564

  15. The effects of adult sex ratio on mating competition in male and female guppies (Poecilia reticulata) in two wild populations.

    PubMed

    Chuard, Pierre J C; Brown, Grant E; Grant, James W A

    2016-08-01

    When competing for mates, males typically exhibit higher rates of intrasexual aggression and courtship than females. Operational sex ratio, represented here by adult sex ratio (ASR) as a proxy, is likely the best predictor of this competition, which typically increases between members of one sex as members of the opposite sex become rarer. Moreover, in populations subject to high predation, males often decrease mating competitive behaviour due to predation risk. We explored the combined effects of ASR and population of origin (low vs. high ambient predation risk) on mating competition in male and female wild-caught Trinidadian guppies. Both male and female aggression rates increased with ASR, but the increase for males was only significant in the low-predation population. In regard to male mating tactics, courtship propensity was unaffected by ASR, while the propensity to sneak increased at male-biased ASRs. Guppies from a high predation population had lower aggression rates than their low predation counterpart, but male courtship and sneaking attempts did not differ between populations. Surprisingly, females were just as aggressive as males when competing for mates. These results highlight the trade-offs between antipredator and agonistic behaviour, which may affect sexual selection pressures in wild populations. PMID:27208810

  16. Spatial variation in adult sex ratio across multiple scales in the invasive golden apple snail, Pomacea canaliculata.

    PubMed

    Xu, Meng; Fang, Miao; Yang, Yexin; Dick, Jaimie T A; Song, Hongmei; Luo, Du; Mu, Xidong; Gu, Dangen; Luo, Jianren; Hu, Yinchang

    2016-04-01

    Adult sex ratio (ASR) has critical effects on behavior and life history and has implications for population demography, including the invasiveness of introduced species. ASR exhibits immense variation in nature, yet the scale dependence of this variation is rarely analyzed. In this study, using the generalized multilevel models, we investigated the variation in ASR across multiple nested spatial scales and analyzed the underlying causes for an invasive species, the golden apple snail Pomacea canaliculata. We partitioned the variance in ASR to describe the variations at different scales and then included the explanatory variables at the individual and group levels to analyze the potential causes driving the variation in ASR. We firstly determined there is a significant female-biased ASR for this species when accounting for the spatial and temporal autocorrelations of sampling. We found that, counter to nearly equal distributed variation at plot, habitat and region levels, ASR showed little variation at the town level. Temperature and precipitation at the region level were significantly positively associated with ASR, whereas the individual weight, the density characteristic, and sampling time were not significant factors influencing ASR. Our study suggests that offspring sex ratio of this species may shape the general pattern of ASR in the population level while the environmental variables at the region level translate the unbiased offspring sex ratio to the female-biased ASR. Future research should consider the implications of climate warming on the female-biased ASR of this invasive species and thus on invasion pattern. PMID:27069581

  17. Sex ratios in pheasant research and management

    USGS Publications Warehouse

    Dale, F.H.

    1952-01-01

    Sex ratios are of primary importance in interpretation of extensive studies of pheasant populations. They are necessary for converting crowing-cock indices to population estimates even where annual trends are to be studied in the same area. Reliability of population estimates from hunting season kill of pheasants suffers primarily from inability to estimate sex ratios accurately. Fall sex ratio is an index to production and where adult sex ratios are divergent can serve as a good check on production per hen. Age ratios of cocks cannot be interpreted directly as an index of productivity, even within the boundaries of one state, unless adult sex ratios are known. The relationship between observed and actual sex ratio varies significantly from season to season and according to the method of observation. In view of their importance in population studies and the lack of reliability of present methods, it is believed that intensive studies on techniques for obtaining sex ratios are a major need in pheasant research.

  18. ``sex Ratio'' Meiotic Drive in Drosophila Testacea

    PubMed Central

    James, A. C.; Jaenike, J.

    1990-01-01

    We document the occurrence of ``sex ratio'' meiotic drive in natural populations of Drosophila testacea. ``Sex ratio'' males sire >95% female offspring. Genetic analysis reveals that this effect is due to a meiotically driven X chromosome, as in other species of Drosophila in which ``sex ratio'' has been found. In contrast to other drosophilids, the ``sex ratio'' and standard chromosomes of D. testacea do not differ in gene arrangement, implying that the effect may be due to a single genetic factor in this species. In all likelihood, the ``sex ratio'' condition has evolved independently in D. testacea and in the Drosophila obscura species group, as the loci responsible for the effect occur on different chromosomal elements. An important ecological consequence of ``sex ratio'' is that natural populations of D. testacea exhibit a strong female bias. Because D. testacea mates, oviposits, and feeds as adults and larvae on mushrooms, this species provides an excellent opportunity to study the selective factors in nature that prevent ``sex ratio'' chromosomes from increasing to fixation and causing the extinction of the species. PMID:2249763

  19. The sex ratio at birth.

    PubMed

    Rubin, E

    1967-10-01

    Several aspects of the disparity in birth ratio of males over females are discussed including variations among different races, variations by order of birth, by age of the parent, and in multiple births. Avenues of statistical exploration are suggested in an attempt to indicate certain peculiarities in nature. The Negro population in the United States has a sex ratio of 102 males to 100 females as opposed to 105:100 for whites, a highly significant difference. Inferences from these statistics are suggested for study of the sex ratios of mixed unions. The group classified as Mulatto show a lower sex ratio and further analysis of this was suggested including examination of slave records. For the white population sex ratio declines from 106.2 to 102.9 between 1st order and 7th order births. This is highly significant. However, nonwhite determinations were more irregular. Data limitations on sex ratio by age of parent prevented conclusive results. Multiple births among whites show a decline from 105.3 for single live births to 103.2 for twins and 86.1 for all other plural deliveries. Among nonwhites these ratios are 102.3, 99.7, and 102.6 respectively. Further information should be developed using the multiple facts relating to the sex ratio at birth. PMID:12275623

  20. Sex ratios in bumble bees

    PubMed Central

    Bourke, A. F. G.

    1997-01-01

    The median proportion of investment in females among 11 populations of seven bumble bee (Bombus) species was 0.32 (range 0.07 to 0.64). By contrast, two species of workerless social parasites in the related genus Psithyrus had female-biased sex allocation, the reasons for which remain unclear. Male-biased sex allocation in Bombus contradicts the predictions of Trivers and Hare's sex ratio model for the social Hymenoptera, which are that the population sex investment ratio should be 0.5 (1:1) under queen control and 0.75 (3:1 females:males) under worker control (assuming single, once-mated, outbred queens and non-reproductive workers). Male bias in Bombus does not appear to be either an artefact, or purely the result of symbiotic sex ratio distorters. According to modifications of the Trivers–Hare model, the level of worker male-production in Bombus is insufficient to account for observed levels of male bias. There is also no evidence that male bias arises from either local resource competition (related females compete for resources) or local mate enhancement (related males cooperate in securing mates). Bulmer presented models predicting sexual selection for protandry (males are produced before females) in annual social Hymenoptera and, as a consequence (given some parameter values), male-biased sex allocation. Bumble bees fit the assumptions of Bulmer's models and are protandrous. These models therefore represent the best current explanation for the bees' male-biased sex investment ratios. This conclusion suggests that the relative timing of the production of the sexes strongly influences sex allocation in the social Hymenoptera.

  1. The effect of sex ratios on suicide.

    PubMed

    Kuroki, Masanori

    2014-12-01

    Whereas sex ratios are likely to affect the likelihood of marriage, how sex ratios affect health and survival is underexplored. This study uses suicide as a measure of mental health and examines how suicides are affected by sex ratios. As women tend to marry men older than themselves, shrinking populations will lead to higher sex ratios (i.e., higher proportions of men) in the marriage market. Using data from Japan, I find that high sex ratios, both early-life and current, are correlated with higher male suicide rates, whereas female suicide rates are generally not affected. The results of this study have important implications for public health in countries where imbalanced sex ratios are a concern. PMID:23943552

  2. Sustainable sex ratio in lattice populations

    NASA Astrophysics Data System (ADS)

    Tainaka, K.; Hayashi, T.; Yoshimura, J.

    2006-05-01

    We present a lattice model of mating populations. Simulation is performed by two different methods: local and global interactions. Simulation results account for the reason why the observed sex ratio is nearly one half in many animals. The male-biased sex ratio, such as in human populations, is also explained.

  3. Haplodiploidy, sex-ratio adjustment, and eusociality.

    PubMed

    Gardner, Andy; Ross, Laura

    2013-03-01

    Hamilton's "haplodiploidy hypothesis" holds that inflated sororal relatedness has promoted altruistic sib rearing in haplodiploids, potentially explaining their apparent predisposition to eusociality. Here, we suggest that haplodiploidy may instead promote eusociality simply by facilitating sex-ratio adjustment. Specifically, haplodiploidy may enable sex-ratio bias toward the more helpful sex, owing to "local resource enhancement," and such sex-ratio bias may promote the evolution of helping by individuals of that sex, owing to the "rarer-sex effect." This could explain why haplodiploidy appears to have been important for eusociality in taxa with only female helpers, such as ants, wasps, and bees, but not in taxa with both male and female helpers, such as termites. PMID:23448893

  4. On the variability of alligator sex ratios

    USGS Publications Warehouse

    Nichols, J.D.; Chabreck, R.H.

    1980-01-01

    Samples of alligators from wild and 'farm' populations exhibited disproportionate sex ratios. Males predominated among young alligators from wild populations, whereas females were much more abundant than males in the farm population, where resources were superabundant. These results and other considerations lead us to hypothesize that environmental factors influence sex determination in alligators. During favorable environmental conditions natural selection is expected to favor a preponderance of the sex whose individuals exhibit the greater environmentally associated variation in relative fitness. We hypothesize that environmentally associated variation in age at sexual maturity of females produces sufficient variation in relative fitness of females to result in selection for low sex ratios during periods of resource abundance.

  5. Patterns of Family Formation in Response to Sex Ratio Variation.

    PubMed

    Schacht, Ryan; Kramer, Karen L

    2016-01-01

    The impact that unbalanced sex ratios have on health and societal outcomes is of mounting contemporary concern. However, it is increasingly unclear whether it is male- or female-biased sex ratios that are associated with family and social instability. From a socio-demographic perspective, male-biased sex ratios leave many men unable to find a mate, elevating competition among males, disrupting family formation and negatively affecting social stability. In contrast, from a mating-market perspective, males are expected to be less willing to marry and commit to a family when the sex ratio is female-biased and males are rare. Here we use U.S. data to evaluate predictions from these competing frameworks by testing the relationship between the adult sex ratio and measures of family formation. We find that when women are rare men are more likely to marry, be part of a family and be sexually committed to a single partner. Our results do not support claims that male-biased sex ratios lead to negative family outcomes due to a surplus of unmarried men. Rather, our results highlight the need to pay increased attention to female-biased sex ratios. PMID:27556401

  6. Patterns of Family Formation in Response to Sex Ratio Variation

    PubMed Central

    Schacht, Ryan; Kramer, Karen L.

    2016-01-01

    The impact that unbalanced sex ratios have on health and societal outcomes is of mounting contemporary concern. However, it is increasingly unclear whether it is male- or female-biased sex ratios that are associated with family and social instability. From a socio-demographic perspective, male-biased sex ratios leave many men unable to find a mate, elevating competition among males, disrupting family formation and negatively affecting social stability. In contrast, from a mating-market perspective, males are expected to be less willing to marry and commit to a family when the sex ratio is female-biased and males are rare. Here we use U.S. data to evaluate predictions from these competing frameworks by testing the relationship between the adult sex ratio and measures of family formation. We find that when women are rare men are more likely to marry, be part of a family and be sexually committed to a single partner. Our results do not support claims that male-biased sex ratios lead to negative family outcomes due to a surplus of unmarried men. Rather, our results highlight the need to pay increased attention to female-biased sex ratios. PMID:27556401

  7. Effects of salinity on egg and fecal pellet production, development and survival, adult sex ratio and total life span in the calanoid copepod, Acartia tonsa: a laboratory study

    NASA Astrophysics Data System (ADS)

    Shayegan, Majid; Esmaeili Fereidouni, Abolghasem; Agh, Naser; Jani Khalili, Khosrow

    2016-07-01

    The effects of salinity on the copepod, Acartia tonsa in terms of daily egg production rate (EPR), hatching success, fecal pellet production rate (FPR), naupliar development time and survival, sex ratio, and total life span were determined in laboratory conditions through three experiments. In experiment 1, EPR, hatching success, and FPR of individual females were monitored at salinities of 13, 20, 35 and 45 during short-periods (seven consecutive days). Results show EPR was affected by salinity with the highest outputs recorded at 20 and 35, respectively, which were considerably higher than those at 13 and 45. Mean FPR was also higher in 35 and 20. In experiment 2, the same parameters were evaluated over total life span of females (long-term study). The best EPR and FPR were observed in 35, which was statistically higher than at 13 and 20. In experiment 3, survival rates of early nauplii until adult stage were lowest at a salinity of 13. The development time increased with increasing of salinity. Female percentage clearly decreased with increasing salinity. Higher female percentages (56.7% and 52.2%, respectively) were significantly observed at two salinities of 13 and 20 compared to that at 35 (25%). Total longevity of females was not affected by salinity increment. Based on our results, for mass culture we recommend that a salinity of 35 be adopted due to higher reproductive performances, better feeding, and faster development of A. tonsa.

  8. Effects of salinity on egg and fecal pellet production, development and survival, adult sex ratio and total life span in the calanoid copepod, Acartia tonsa: a laboratory study

    NASA Astrophysics Data System (ADS)

    Shayegan, Majid; Esmaeili Fereidouni, Abolghasem; Agh, Naser; Jani Khalili, Khosrow

    2016-01-01

    The effects of salinity on the copepod, Acartia tonsa in terms of daily egg production rate (EPR), hatching success, fecal pellet production rate (FPR), naupliar development time and survival, sex ratio, and total life span were determined in laboratory conditions through three experiments. In experiment 1, EPR, hatching success, and FPR of individual females were monitored at salinities of 13, 20, 35 and 45 during short-periods (seven consecutive days). Results show EPR was affected by salinity with the highest outputs recorded at 20 and 35, respectively, which were considerably higher than those at 13 and 45. Mean FPR was also higher in 35 and 20. In experiment 2, the same parameters were evaluated over total life span of females (long-term study). The best EPR and FPR were observed in 35, which was statistically higher than at 13 and 20. In experiment 3, survival rates of early nauplii until adult stage were lowest at a salinity of 13. The development time increased with increasing of salinity. Female percentage clearly decreased with increasing salinity. Higher female percentages (56.7% and 52.2%, respectively) were significantly observed at two salinities of 13 and 20 compared to that at 35 (25%). Total longevity of females was not affected by salinity increment. Based on our results, for mass culture we recommend that a salinity of 35 be adopted due to higher reproductive performances, better feeding, and faster development of A. tonsa.

  9. Kinship Institutions and Sex Ratios in India

    PubMed Central

    CHAKRABORTY, TANIKA; KIM, SUKKOO

    2010-01-01

    This article explores the relationship between kinship institutions and sex ratios in India at the turn of the twentieth century. Because kinship rules vary by caste, language, religion, and region, we construct sex ratios by these categories at the district level by using data from the 1901 Census of India for Punjab (North), Bengal (East), and Madras (South). We find that the male-to-female sex ratio varied positively with caste rank, fell as one moved from the North to the East and then to the South, was higher for Hindus than for Muslims, and was higher for northern Indo-Aryan speakers than for the southern Dravidian-speaking people. We argue that these systematic patterns in the data are consistent with variations in the institution of family, kinship, and inheritance. PMID:21308567

  10. Sex ratio effects on reproductive strategies in humans

    PubMed Central

    Schacht, Ryan; Borgerhoff Mulder, Monique

    2015-01-01

    Characterizations of coy females and ardent males are rooted in models of sexual selection that are increasingly outdated. Evolutionary feedbacks can strongly influence the sex roles and subsequent patterns of sex differentiated investment in mating effort, with a key component being the adult sex ratio (ASR). Using data from eight Makushi communities of southern Guyana, characterized by varying ASRs contingent on migration, we show that even within a single ethnic group, male mating effort varies in predictable ways with the ASR. At male-biased sex ratios, men's and women's investment in mating effort are indistinguishable; only when men are in the minority are they more inclined towards short-term, low investment relationships than women. Our results support the behavioural ecological tenet that reproductive strategies are predictable and contingent on varying situational factors. PMID:26064588

  11. Male pygmy hippopotamus influence offspring sex ratio

    PubMed Central

    Saragusty, Joseph; Hermes, Robert; Hofer, Heribert; Bouts, Tim; Göritz, Frank; Hildebrandt, Thomas B.

    2012-01-01

    Pre-determining fetal sex is against the random and equal opportunity that both conceptus sexes have by nature. Yet, under a wide variety of circumstances, populations shift their birth sex ratio from the expected unity. Here we show, using fluorescence in situ hybridization, that in a population of pygmy hippopotamus (Choeropsis liberiensis) with 42.5% male offspring, males bias the ratio of X- and Y-chromosome-bearing spermatozoa in their ejaculates, resulting in a 0.4337±0.0094 (mean±s.d.) proportion of Y-chromosome-bearing spermatozoa. Three alternative hypotheses for the shifted population sex ratio were compared: female counteract male, female indifferent, or male and female in agreement. We conclude that there appears little or no antagonistic sexual conflict, unexpected by prevailing theories. Our results indicate that males possess a mechanism to adjust the ratio of X- and Y-chromosome-bearing spermatozoa in the ejaculate, thereby substantially expanding currently known male options in sexual conflict. PMID:22426218

  12. Disproportionate sex ratios of wolf pups

    USGS Publications Warehouse

    Mech, L.D.

    1975-01-01

    Males comprised 66 percent of wild wolf (Canis lupus) pups from a saturated, high-density wolf range in northeastern Minnesota, possibly reflecting disproportionate conception of males. Packs from areas of lower wolf density in other areas of Minnesota had equal sex ratios of pups or a disproportionate number of female pups. Captive wolves showed a slight preponderance of male pups.

  13. An equal sex ratio followed by differential sex mortality causes overestimation of females in gall midges: no evidence for sex ratio regulation.

    PubMed

    Tabadkani, Seyed Mohammad; Ashouri, Ahmad; Qolizadeh, Majid

    2012-06-01

    Monogeny, the production of unisexual broods by individual females, has been recognized for nearly 80 years. The genetic nature of gall midges' sex determination predicts an equal numbers of male-producing and female-producing females in the populations such that the overall sex ratio is expected to be nearly 1:1. However, observations of some strictly monogenous populations with biased sex ratio, mainly toward females, have raised the question of whether gall midges are able to adjust their offspring sex ratio in response to changes in environmental conditions, and some authors have even considered sex ratio regulation as a strong force in the course of the evolution of monogeny. In this paper, first, by studying the sex ratio variations of the predatory gall midge, Aphidoletes aphidimyza within a generation, we showed that adult males emerge up to 1 day earlier and have shorter life span than females (less than 4 days and up to 6 days, respectively). Although, the sex ratio of A. aphidimyza at the time of emergence was nearly 1:1 (52.41% males), a simple population simulation indicated that the differential mortality of sexes can lead to a female-biased sex ratio estimation (57.88% females) under random sampling in the natural environments. Our results imply that the primary sex ratio of monogenous gall midges is nearly 1:1 and that the arrhenogenic/thelygenic gall midges are not able to alter the number of their male/female progenies in response to changes in environmental conditions. PMID:22643882

  14. An equal sex ratio followed by differential sex mortality causes overestimation of females in gall midges: no evidence for sex ratio regulation

    NASA Astrophysics Data System (ADS)

    Tabadkani, Seyed Mohammad; Ashouri, Ahmad; Qolizadeh, Majid

    2012-06-01

    Monogeny, the production of unisexual broods by individual females, has been recognized for nearly 80 years. The genetic nature of gall midges' sex determination predicts an equal numbers of male-producing and female-producing females in the populations such that the overall sex ratio is expected to be nearly 1:1. However, observations of some strictly monogenous populations with biased sex ratio, mainly toward females, have raised the question of whether gall midges are able to adjust their offspring sex ratio in response to changes in environmental conditions, and some authors have even considered sex ratio regulation as a strong force in the course of the evolution of monogeny. In this paper, first, by studying the sex ratio variations of the predatory gall midge, Aphidoletes aphidimyza within a generation, we showed that adult males emerge up to 1 day earlier and have shorter life span than females (less than 4 days and up to 6 days, respectively). Although, the sex ratio of A. aphidimyza at the time of emergence was nearly 1:1 (52.41 % males), a simple population simulation indicated that the differential mortality of sexes can lead to a female-biased sex ratio estimation (57.88 % females) under random sampling in the natural environments. Our results imply that the primary sex ratio of monogenous gall midges is nearly 1:1 and that the arrhenogenic/thelygenic gall midges are not able to alter the number of their male/female progenies in response to changes in environmental conditions.

  15. Sex Ratios at Birth and Environmental Temperatures

    NASA Astrophysics Data System (ADS)

    Lerchl, Alexander

    The relationship between average monthly air temperature and sex ratios at birth (SRB) was analyzed for children born in Germany during the period 1946-1995. Both the absolute temperature and - more markedly - the monthly temperature deviations from the overall mean were significantly positively correlated with the SRB (P<0.01) when temperatures were time-lagged against the SRB data by -10 or -11months. It is concluded that the sex of the offspring is partially determined by environmental temperatures prior to conception.

  16. Sex ratios at birth after induced abortion

    PubMed Central

    Urquia, Marcelo L.; Moineddin, Rahim; Jha, Prabhat; O’Campo, Patricia J.; McKenzie, Kwame; Glazier, Richard H.; Henry, David A.; Ray, Joel G.

    2016-01-01

    Background: Skewed male:female ratios at birth have been observed among certain immigrant groups. Data on abortion practices that might help to explain these findings are lacking. Methods: We examined 1 220 933 births to women with up to 3 consecutive singleton live births between 1993 and 2012 in Ontario. Records of live births, and induced and spontaneous abortions were linked to Canadian immigration records. We determined associations of male:female infant ratios with maternal birthplace, sex of the previous living sibling(s) and prior spontaneous or induced abortions. Results: Male:female infant ratios did not appreciably depart from the normal range among Canadian-born women and most women born outside of Canada, irrespective of the sex of previous children or the characteristics of prior abortions. However, among infants of women who immigrated from India and had previously given birth to 2 girls, the overall male:female ratio was 1.96 (95% confidence interval [CI] 1.75–2.21) for the third live birth. The male:female infant ratio after 2 girls was 1.77 (95% CI 1.26–2.47) times higher if the current birth was preceded by 1 induced abortion, 2.38 (95% CI 1.44–3.94) times higher if preceded by 2 or more induced abortions and 3.88 (95% CI 2.02–7.50) times higher if the induced abortion was performed at 15 weeks or more gestation relative to no preceding abortion. Spontaneous abortions were not associated with male-biased sex ratios in subsequent births. Interpretation: High male:female ratios observed among infants born to women who immigrated from India are associated with induced abortions, especially in the second trimester of pregnancy. PMID:27067818

  17. Maternal transmission, sex ratio distortion, and mitochondria

    PubMed Central

    Perlman, Steve J.; Hodson, Christina N.; Hamilton, Phineas T.; Opit, George P.; Gowen, Brent E.

    2015-01-01

    In virtually all multicellular eukaryotes, mitochondria are transmitted exclusively through one parent, usually the mother. In this short review, we discuss some of the major consequences of uniparental transmission of mitochondria, including deleterious effects in males and selection for increased transmission through females. Many of these consequences, particularly sex ratio distortion, have well-studied parallels in other maternally transmitted genetic elements, such as bacterial endosymbionts of arthropods. We also discuss the consequences of linkage between mitochondria and other maternally transmitted genetic elements, including the role of cytonuclear incompatibilities in maintaining polymorphism. Finally, as a case study, we discuss a recently discovered maternally transmitted sex ratio distortion in an insect that is associated with extraordinarily divergent mitochondria. PMID:25870270

  18. Variation in adult sex ratio alters the association between courtship, mating frequency and paternity in the lek-forming fruitfly Ceratitis capitata.

    PubMed

    Leftwich, P T; Edward, D A; Alphey, L; Gage, M J G; Chapman, T

    2012-09-01

    The intensity with which males deliver courtship and the frequency with which they mate are key components of male reproductive success. However, we expect the strength of the relationship between these traits and a male's overall paternity to be strongly context dependent, for example to be altered significantly by the extent of post-mating competition. We tested this prediction in a lekking insect, Ceratitis capitata (medfly). We examined the effect of manipulating the sex ratio from male- to female-biased (high and low male competition, respectively) on courtship behaviour, mating frequency and paternity of focal males. Under high male competition, focal males delivered significantly more courtship but gained lower paternity than under lower competition. Paternity was positively associated with mating frequency and small residual testes size. However, the association between mating frequency and paternity was significantly stronger under low competition. We conclude that manipulation of sex ratio significantly altered the predictors of mating success and paternity. The relationship between pre- and post-mating success is therefore plastic and alters according to the prevailing level of competition. The results highlight the importance of post-copulatory processes in lekking species and illuminate selection pressures placed on insects such as medflies that are mass reared for pest control. PMID:22725666

  19. Maladaptive sex ratio adjustment by a sex-changing shrimp in selective-fishing environments.

    PubMed

    Chiba, Susumu; Yoshino, Kenji; Kanaiwa, Minoru; Kawajiri, Toshifumi; Goshima, Seiji

    2013-05-01

    1. Selective harvesting is acknowledged as a serious concern in efforts to conserve wild animal populations. In fisheries, most studies have focused on gradual and directional changes in the life-history traits of target species. While such changes represent the ultimate response of harvested animals, it is also well known that the life history of target species plastically alters with harvesting. However, research on the adaptive significance of these types of condition-dependent changes has been limited. 2. We explored the adaptive significance of annual changes in the age at sex-change of the protandrous (male-first) hermaphroditic shrimp and examined how selective harvesting affects life-history variation, by conducting field observations across 13 years and a controlled laboratory experiment. In addition, we considered whether plastic responses by the shrimp would be favourable, negligible or negative with respect to the conservation of fishery resources. 3. The age at sex-change and the population structure of the shrimp fluctuated between years during the study period. The results of the field observations and laboratory experiment both indicated that the shrimp could plastically change the timing of sex-change in accordance with the age structure of the population. These findings provide the first concrete evidence of adult sex ratio adjustment by pandalid shrimp, a group that has been treated as a model in the sex allocation theory. 4. The sex ratio adjustment by the shrimp did not always seem to be sufficient, however, as the supplement of females is restricted by their annual somatic growth rate. In addition, adjusted sex ratios are further skewed by the unintentional female-selectivity of fishing activity prior to the breeding season, indicating that the occurrence of males that have postponed sex-change causes sex ratio adjustment to become unfavourable. 5. We conclude that the plastic responses of harvested animals in selective fishing environments

  20. Consistent sex ratio bias of individual female dragon lizards

    PubMed Central

    Uller, Tobias; Mott, Beth; Odierna, Gaetano; Olsson, Mats

    2006-01-01

    Sex ratio evolution relies on genetic variation in either the phenotypic traits that influence sex ratios or sex-determining mechanisms. However, consistent variation among females in offspring sex ratio is rarely investigated. Here, we show that female painted dragons (Ctenophorus pictus) have highly repeatable sex ratios among clutches within years. A consistent effect of female identity could represent stable phenotypic differences among females or genetic variation in sex-determining mechanisms. Sex ratios were not correlated with female size, body condition or coloration. Furthermore, sex ratios were not influenced by incubation temperature. However, the variation among females resulted in female-biased mean population sex ratios at hatching both within and among years. PMID:17148290

  1. Parasite Stress Predicts Offspring Sex Ratio

    PubMed Central

    Dama, Madhukar Shivajirao

    2012-01-01

    In this study, I predict that the global variation of offspring sex ratio might be influenced in part by the level of parasite stress. From an energetic standpoint, higher gestational costs of producing a male offspring could decrease male births in a population with limited resources. This implies that, any factor that limits the parental resources could be expected to favor female offspring production. Human sex ratio at birth (SRB) is believed to be influenced by numerous socioeconomic, biological, and environmental factors. Here, I test a prediction that parasite stress, by virtue of its effects on the general health condition, may limit the parental investment ability and therefore could influence the SRB at the population level. The statistical analysis supports this prediction, and show that the level of parasite stress has a significant inverse relation with population SRB across the world. Further, this relation is many-folds stronger than the association of SRB with other factors, like; polygyny, fertility, latitude, and son-preference. Hence, I propose that condition affecting ability of parasites (but not adaptive significance) could be a likely causal basis for the striking variation of SRB across populations. PMID:23049967

  2. Sex ratio bias, male aggression, and population collapse in lizards.

    PubMed

    Le Galliard, Jean-François; Fitze, Patrick S; Ferrière, Régis; Clobert, Jean

    2005-12-13

    The adult sex ratio (ASR) is a key parameter of the demography of human and other animal populations, yet the causes of variation in ASR, how individuals respond to this variation, and how their response feeds back into population dynamics remain poorly understood. A prevalent hypothesis is that ASR is regulated by intrasexual competition, which would cause more mortality or emigration in the sex of increasing frequency. Our experimental manipulation of populations of the common lizard (Lacerta vivipara) shows the opposite effect. Male mortality and emigration are not higher under male-biased ASR. Rather, an excess of adult males begets aggression toward adult females, whose survival and fecundity drop, along with their emigration rate. The ensuing prediction that adult male skew should be amplified and total population size should decline is supported by long-term data. Numerical projections show that this amplifying effect causes a major risk of population extinction. In general, such an "evolutionary trap" toward extinction threatens populations in which there is a substantial mating cost for females, and environmental changes or management practices skew the ASR toward males. PMID:16322105

  3. The human sex ratio from conception to birth

    PubMed Central

    Orzack, Steven Hecht; Stubblefield, J. William; Akmaev, Viatcheslav R.; Colls, Pere; Munné, Santiago; Scholl, Thomas; Steinsaltz, David; Zuckerman, James E.

    2015-01-01

    We describe the trajectory of the human sex ratio from conception to birth by analyzing data from (i) 3- to 6-d-old embryos, (ii) induced abortions, (iii) chorionic villus sampling, (iv) amniocentesis, and (v) fetal deaths and live births. Our dataset is the most comprehensive and largest ever assembled to estimate the sex ratio at conception and the sex ratio trajectory and is the first, to our knowledge, to include all of these types of data. Our estimate of the sex ratio at conception is 0.5 (proportion male), which contradicts the common claim that the sex ratio at conception is male-biased. The sex ratio among abnormal embryos is male-biased, and the sex ratio among normal embryos is female-biased. These biases are associated with the abnormal/normal state of the sex chromosomes and of chromosomes 15 and 17. The sex ratio may decrease in the first week or so after conception (due to excess male mortality); it then increases for at least 10–15 wk (due to excess female mortality), levels off after ∼20 wk, and declines slowly from 28 to 35 wk (due to excess male mortality). Total female mortality during pregnancy exceeds total male mortality. The unbiased sex ratio at conception, the increase in the sex ratio during the first trimester, and total mortality during pregnancy being greater for females are fundamental insights into early human development. PMID:25825766

  4. Sex investment ratios in eusocial Hymenoptera support inclusive fitness theory.

    PubMed

    Bourke, A F G

    2015-11-01

    Inclusive fitness theory predicts that sex investment ratios in eusocial Hymenoptera are a function of the relatedness asymmetry (relative relatedness to females and males) of the individuals controlling sex allocation. In monogynous ants (with one queen per colony), assuming worker control, the theory therefore predicts female-biased sex investment ratios, as found in natural populations. Recently, E.O. Wilson and M.A. Nowak criticized this explanation and presented an alternative hypothesis. The Wilson-Nowak sex ratio hypothesis proposes that, in monogynous ants, there is selection for a 1 : 1 numerical sex ratio to avoid males remaining unmated, which, given queens exceed males in size, results in a female-biased sex investment ratio. The hypothesis also asserts that, contrary to inclusive fitness theory, queens not workers control sex allocation and queen-worker conflict over sex allocation is absent. Here, I argue that the Wilson-Nowak sex ratio hypothesis is flawed because it contradicts Fisher's sex ratio theory, which shows that selection on sex ratio does not maximize the number of mated offspring and that the sex ratio proposed by the hypothesis is not an equilibrium for the queen. In addition, the hypothesis is not supported by empirical evidence, as it fails to explain 'split' (bimodal) sex ratios or data showing queen and worker control and ongoing queen-worker conflict. By contrast, these phenomena match predictions of inclusive fitness theory. Hence, the Wilson-Nowak sex ratio hypothesis fails both as an alternative hypothesis for sex investment ratios in eusocial Hymenoptera and as a critique of inclusive fitness theory. PMID:26238365

  5. Large-Scale Age-Dependent Skewed Sex Ratio in a Sexually Dimorphic Avian Scavenger

    PubMed Central

    Lambertucci, Sergio A.; Carrete, Martina; Donázar, José Antonio; Hiraldo, Fernando

    2012-01-01

    Age-dependent skewed sex ratios have been observed in bird populations, with adult males generally outnumbering females. This trend is mainly driven by higher female mortality, sometimes associated with anthropogenic factors. Despite the large amount of work on bird sex ratios, research examining the spatial stability of adult sex ratios is extremely scarce. The Andean condor (Vultur gryphus) is the only bird of prey with strong sexual dimorphism favouring males (males are 30% heavier than females). By examining data from most of its South-American range, we show that while the juvenile sex ratio is balanced, or even female-skewed, the sex ratio becomes increasing male-skewed with age, with adult males outnumbering females by >20%, and, in some cases by four times more. This result is consistent across regions and independent of the nature of field data. Reasons for this are unknown but it can be hypothesized that the progressive disappearance of females may be associated with mortality caused by anthropogenic factors. This idea is supported by the asymmetric habitat use by the two sexes, with females scavenging in more humanized areas. Whatever the cause, male-skewed adult sex ratios imply that populations of this endangered scavenger face higher risks of extinction than previously believed. PMID:23029488

  6. [[On the change of sex ratio by the Japanese zodiac

    PubMed

    Sakai, H

    1989-04-01

    Changes in the sex ratio in Japan from 1899 to 1986 are analyzed using data from official sources. The emphasis is on differences in the sex ratio according to the signs of the Japanese zodiac. The author notes that although the significance of the zodiac on the sex ratio has been decreasing since the early 1970s, it still has a measurable impact. PMID:12282506

  7. Modeling Landscape-Level Spatial Variation in Sex Ratio Skew in the Mountain Pine Beetle (Coleoptera: Curculionidae).

    PubMed

    James, Patrick M A; Janes, Jasmine K; Roe, Amanda D; Cooke, Barry J

    2016-08-01

    Through their influence on effective population sizes, sex ratio skew affects population dynamics. We examined spatial variation in female-biased sex ratios in the mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreak in western Canada to better understand how environmental context affects sex ratio skew. Our specific objectives were to: 1) characterize spatial variation in mountain pine beetle sex ratio; 2) test previously asserted hypotheses that beetle sex ratio varies with tree diameter and year in outbreak; and 3) develop predictive models of sex ratio skew for larval and adult populations. Using logistic regression, we modeled the probability that an individual beetle (n = 2,369) was female as a function of multiple environmental variables across 34 stands in British Columbia and Alberta, Canada. We identified a consistent female-biased sex ratio with significantly greater skew in adults (2:1, n = 713) than in larvae (1.76:1, n = 1,643). We found that the proportion of larval females increased with decreasing tree size and with outbreak age. However, adults did not respond to tree size and larvae did not respond to outbreak age. Predictive models differed between larvae and adults. All identified models perform well and included predictors related to weather, tree diameter, and year in outbreak. Female-biased sex ratios appear to originate from differential male mortality during development rather than from sex-biased oviposition, suggesting sex ratio skew is not the cause of outbreaks, but rather a consequence. PMID:27209334

  8. Age and Sex Ratios in a High-Density Wild Red-Legged Partridge Population.

    PubMed

    Nadal, Jesús; Ponz, Carolina; Margalida, Antoni

    2016-01-01

    The dynamics of a wild red-legged partridge population were examined over a 14-year period in Spain to identify patterns in age and sex ratios in relation to weather parameters, and to assess the importance of these parameters in population dynamics and management. The results gave age ratios of 1.07 (but 2.13 in July counts), juvenile sex ratios of 1.01 and adult sex ratios of 1.47. Overall, 12% more females were hatched and female juvenile mortality was 7.3% higher than in males. Sex differential mortality explains the 19.2% deficit in adult females, which are more heavily predated than males during the breeding period. Accordingly, age ratios are dependent on sex ratios and both are density dependent. Over time, ratios and density changes appear to be influenced by weather and management. When the habitat is well conserved, partridge population dynamics can be explained by a causal chain: weather operates on net primary production, thereby affecting partridge reproduction and predation and, as a result, age and sex ratios in the October population. A reduction in the impact of predation (i.e. the effects of ground predators on eggs, chicks and breeding females) is the key factor to improve the conservation of partridge populations and associated biological processes. PMID:27508503

  9. Age and Sex Ratios in a High-Density Wild Red-Legged Partridge Population

    PubMed Central

    Nadal, Jesús; Ponz, Carolina; Margalida, Antoni

    2016-01-01

    The dynamics of a wild red-legged partridge population were examined over a 14-year period in Spain to identify patterns in age and sex ratios in relation to weather parameters, and to assess the importance of these parameters in population dynamics and management. The results gave age ratios of 1.07 (but 2.13 in July counts), juvenile sex ratios of 1.01 and adult sex ratios of 1.47. Overall, 12% more females were hatched and female juvenile mortality was 7.3% higher than in males. Sex differential mortality explains the 19.2% deficit in adult females, which are more heavily predated than males during the breeding period. Accordingly, age ratios are dependent on sex ratios and both are density dependent. Over time, ratios and density changes appear to be influenced by weather and management. When the habitat is well conserved, partridge population dynamics can be explained by a causal chain: weather operates on net primary production, thereby affecting partridge reproduction and predation and, as a result, age and sex ratios in the October population. A reduction in the impact of predation (i.e. the effects of ground predators on eggs, chicks and breeding females) is the key factor to improve the conservation of partridge populations and associated biological processes. PMID:27508503

  10. Inter-Annual Variability of Fledgling Sex Ratio in King Penguins

    PubMed Central

    Viblanc, Vincent A.; Gachot-Neveu, Hélène; Beaugey, Magali; Le Maho, Yvon; Le Bohec, Céline

    2014-01-01

    As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (2000–2009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1∶1 equilibrium upon first breeding attempts, as would be expected from Fisher’s classic theory of offspring sex-ratio variation. PMID:25493708

  11. Causes and consequences of spatial variation in sex ratios in a declining bird species.

    PubMed

    Morrison, Catriona A; Robinson, Robert A; Clark, Jacquie A; Gill, Jennifer A

    2016-09-01

    Male-biased sex ratios occur in many bird species, particularly in those with small or declining populations, but the causes of these skews and their consequences for local population demography are rarely known. Within-species variation in sex ratios can help to identify the demographic and behavioural processes associated with such biases. Small populations may be more likely to have skewed sex ratios if sex differences in survival, recruitment or dispersal vary with local abundance. Analyses of species with highly variable local abundances can help to identify these mechanisms and the implications for spatial variation in demography. Many migratory bird species are currently undergoing rapid and severe declines in abundance in parts of their breeding ranges and thus have sufficient spatial variation in abundance to explore the extent of sex ratio biases, their causes and implications. Using national-scale bird ringing data for one such species (willow warbler, Phylloscopus trochilus), we show that sex ratios vary greatly across Britain and that male-biased sites are more frequent in areas of low abundance, which are now widespread across much of south and east England. These sex ratio biases are sufficient to impact local productivity, as the relative number of juveniles caught at survey sites declines significantly with increasing sex ratio skew. Sex differences in survival could influence this sex ratio variation, but we find little evidence for sex differences in survival increasing with sex ratio skew. In addition, sex ratios have become male-biased over the last two decades, but there are no such trends in adult survival rates for males or females. This suggests that lower female recruitment into low abundance sites is contributing to these skews. These findings suggest that male-biased sex ratios in small and declining populations can arise through local-scale sex differences in survival and dispersal, with females recruiting disproportionately into larger

  12. Bayesian Reconstruction of Two-Sex Populations by Age: Estimating Sex Ratios at Birth and Sex Ratios of Mortality1

    PubMed Central

    Wheldon, Mark C.; Raftery, Adrian E.; Clark, Samuel J.; Gerland, Patrick

    2014-01-01

    Summary The original version of Bayesian reconstruction, a method for estimating age-specific fertility, mortality, migration and population counts of the recent past with uncertainty, produced estimates for female-only populations. Here we show how two-sex populations can be similarly reconstructed and probabilistic estimates of various sex ratio quantities obtained. We demonstrate the method by reconstructing the populations of India from 1971 to 2001, Thailand from 1960 to 2000, and Laos from 1985 to 2005. We found evidence that in India, sex ratio at birth exceeded its conventional upper limit of 1.06, and, further, increased over the period of study, with posterior probability above 0.9. In addition, almost uniquely, we found evidence that life expectancy at birth (e0) was lower for females than for males in India (posterior probability for 1971–1976 equal to 0.79), although there was strong evidence for a narrowing of the gap through to 2001. In both Thailand and Laos, we found strong evidence for the more usual result that e0 was greater for females and, in Thailand, that the difference increased over the period of study. PMID:26612972

  13. Sex ratios in fetuses and liveborn infants with autosomal aneuploidy

    SciTech Connect

    Heuther, C.A.; Martin, R.L.M.; Stoppelman, S.M.

    1996-06-14

    Ten data sources were used substantially to increase the available data for estimating fetal and livebirth sex ratios for Patau (trisomy 13), Edwards (trisomy 18), and Down (trisomy 21) syndromes and controls. The fetal sex ratio estimate was 0.88 (N = 584) for trisomy 13, 0.90 (N = 1702) for trisomy 18, and 1.16 (N = 3154) for trisomy 21. All were significantly different from prenatal controls (1.07). The estimated ratios in prenatal controls were 1.28 (N = 1409) for CVSs and 1.06 (N = 49427) for amniocenteses, indicating a clear differential selection against males, mostly during the first half of fetal development. By contrast, there were no sex ratio differences for any of the trisomies when comparing gestational ages <16 and >16 weeks. The livebirth sex ratio estimate was 0.90 (N = 293) for trisomy 13, 0.63 (N = 497) for trisomy 18, and 1.15 (N = 6424) for trisomy 21, the latter two being statistically different than controls (1.05) (N = 3660707). These ratios for trisomies 13 and 18 were also statistically different than the ratio for trisomy 21. Only in trisomy 18 did the sex ratios in fetuses and livebirths differ, indicating a prenatal selection against males >16 weeks. No effects of maternal age or race were found on these estimates for any of the fetal or livebirth trisomies. Sex ratios for translocations and mosaics were also estimated for these aneuploids. Compared to previous estimates, these results are less extreme, most likely because of larger sample sizes and less sample bias. They support the hypothesis that these trisomy sex ratios are skewed at conception, or become so during embryonic development through differential intrauterine selection. The estimate for Down syndrome livebirths is also consistent with the hypothesis that its higher sex ratio is associated with paternal nondisjunction. 36 refs., 5 tabs.

  14. Elevated Mortality among Birds in Chernobyl as Judged from Skewed Age and Sex Ratios

    PubMed Central

    Møller, Anders Pape; Bonisoli-Alquati, Andrea; Rudolfsen, Geir; Mousseau, Timothy A.

    2012-01-01

    Background Radiation has negative effects on survival of animals including humans, although the generality of this claim is poorly documented under low-dose field conditions. Because females may suffer disproportionately from the effects of radiation on survival due to differences in sex roles during reproduction, radiation-induced mortality may result in male-skewed adult sex ratios. Methodology/Principal Finding We estimated the effects of low-dose radiation on adult survival rates in birds by determining age ratios of adults captured in mist nets during the breeding season in relation to background radiation levels around Chernobyl and in nearby uncontaminated control areas. Age ratios were skewed towards yearlings, especially in the most contaminated areas, implying that adult survival rates were reduced in contaminated areas, and that populations in such areas could only be maintained through immigration from nearby uncontaminated areas. Differential mortality in females resulted in a strongly male-skewed sex ratio in the most contaminated areas. In addition, males sang disproportionately commonly in the most contaminated areas where the sex ratio was male skewed presumably because males had difficulty finding and acquiring mates when females were rare. The results were not caused by permanent emigration by females from the most contaminated areas because none of the recaptured birds had changed breeding site, and the proportion of individuals with morphological abnormalities did not differ significantly between the sexes for areas with normal and higher levels of contamination. Conclusions/Significance These findings are consistent with the hypothesis that the adult survival rate of female birds is particularly susceptible to the effects of low-dose radiation, resulting in male skewed sex ratios at high levels of radiation. Such skewed age ratios towards yearlings in contaminated areas are consistent with the hypothesis that an area exceeding 30,000 km2 in

  15. Effects of mating dynamics and crowding on sex ratio variance in mice.

    PubMed

    Krackow, S

    1997-05-01

    Mating units of six virgin females and one adult stud male were established to test for the effects of timing of mating and crowding of pregnant females on litter sex ratios in mice. Females either copulated during periods when no other female of the mating unit copulated simultaneously (single mating condition) or when more than one female copulated (multiple matings condition). Two crowding conditions were imposed on the animals: the females of 14 mating units were placed into individual cages after mating (isolated condition), while females of the other 13 mating units remained in the original group until shortly before littering (crowded condition). Sex ratio variance did not deviate from random expectation in litters arising from the multiple matings periods. However, in litters arising from single mating periods, extreme sex ratios were found significantly less frequently than expected by chance. Higher sex ratio variance in litters arising from multiple matings periods is attributed to the timing of mating being at higher variance under this condition, which is known to affect sex ratios in other rodents. Crowding significantly reduced sex ratio variance further. Reduced sex ratio variance under single mating and crowded conditions is speculated to follow from competition for resources between preimplantation embryos, which may be further increased by stressful effects of crowding. Loss of embryos after implantation appeared not to be responsible for the above effects. PMID:9227361

  16. Sex ratio variation shapes the ecological effects of a globally introduced freshwater fish.

    PubMed

    Fryxell, David C; Arnett, Heather A; Apgar, Travis M; Kinnison, Michael T; Palkovacs, Eric P

    2015-10-22

    Sex ratio and sexual dimorphism have long been of interest in population and evolutionary ecology, but consequences for communities and ecosystems remain untested. Sex ratio could influence ecological conditions whenever sexual dimorphism is associated with ecological dimorphism in species with strong ecological interactions. We tested for ecological implications of sex ratio variation in the sexually dimorphic western mosquitofish, Gambusia affinis. This species causes strong pelagic trophic cascades and exhibits substantial variation in adult sex ratios. We found that female-biased populations induced stronger pelagic trophic cascades compared with male-biased populations, causing larger changes to key community and ecosystem responses, including zooplankton abundance, phytoplankton abundance, productivity, pH and temperature. The magnitude of such effects indicates that sex ratio is important for mediating the ecological role of mosquitofish. Because both sex ratio variation and sexual dimorphism are common features of natural populations, our findings should encourage broader consideration of the ecological significance of sex ratio variation in nature, including the relative contributions of various sexually dimorphic traits to these effects. PMID:26490793

  17. Nestling sex ratio in the Southwestern Willow Flycatcher

    USGS Publications Warehouse

    Paxton, E.H.; Sogge, M.K.; McCarthey, T.D.; Keim, P.

    2002-01-01

    Using molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts. ?? The Cooper Ornithological Society 2002.

  18. Nestling sex ratios in the southwestern willow flycatcher

    USGS Publications Warehouse

    Paxton, E.H.; Sogge, M.K.; McCarthey, Tracy; Keim, Paul

    2002-01-01

    Using molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus) nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs. polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts.

  19. Sex-different response in growth traits to resource heterogeneity explains male-biased sex ratio

    NASA Astrophysics Data System (ADS)

    Matsushita, Michinari; Takao, Mikako; Makita, Akifumi

    2016-08-01

    In dioecious plants, differences in growth traits between sexes in a response to micro-environmental heterogeneity may affect sex ratio bias and spatial distributions. Here, we examined sex ratios, stem growth traits and spatial distribution patterns in the dioecious clonal shrub Aucuba japonica var. borealis, in stands with varying light intensities. We found that male stems were significantly more decumbent (lower height/length ratio) but female stems were upright (higher height/length ratio). Moreover, we found sex-different response in stem density (no. of stems per unit area) along a light intensity gradient; in males the stem density increased with increases in canopy openness, but not in females. The higher sensitivity of males in increasing stem density to light intensity correlated with male-biased sex ratio; fine-scale sex ratio was strongly male-biased as canopy openness increased. There were also differences between sexes in spatial distributions of stems. Spatial segregation of sexes and male patches occupying larger areas than female patches might result from vigorous growth of males under well-lit environments. In summary, females and males showed different growth responses to environmental variation, and this seemed to be one of possible causes for the sex-differential spatial distributions and locally biased sex ratios.

  20. Dioecy and the evolution of sex ratios in ants.

    PubMed

    Wiernasz, Diane C; Cole, Blaine J

    2009-06-01

    Split sex ratios, when some colonies produce only male and others only female reproductives, is a common feature of social insects, especially ants. The most widely accepted explanation for split sex ratios was proposed by Boomsma and Grafen, and is driven by conflicts of interest among colonies that vary in relatedness. The predictions of the Boomsma-Grafen model have been confirmed in many cases, but contradicted in several others. We adapt a model for the evolution of dioecy in plants to make predictions about the evolution of split sex ratios in social insects. Reproductive specialization results from the instability of the evolutionarily stable strategy (ESS) sex ratio, and is independent of variation in relatedness. We test predictions of the model with data from a long-term study of harvester ants, and show that it correctly predicts the intermediate sex ratios we observe in our study species. The dioecy model provides a comprehensive framework for sex allocation that is based on the pay-offs to the colony via production of males and females, and is independent of the genetic variation among colonies. However, in populations where the conditions for the Boomsma-Grafen model hold, kin selection will still lead to an association between sex ratio and relatedness. PMID:19324757

  1. Sex Differences in Adults' Motivation to Achieve

    ERIC Educational Resources Information Center

    van der Sluis, Sophie; Vinkhuyzen, Anna A. E.; Boomsma, Dorret I.; Posthuma, Danielle

    2010-01-01

    Achievement motivation is considered a prerequisite for success in academic as well as non-academic settings. We studied sex differences in academic and general achievement motivation in an adult sample of 338 men and 497 women (ages 18-70 years). Multi-group covariance and means structure analysis (MG-CMSA) for ordered categorical data was used…

  2. Soil moisture and sex ratio in a plant with nuclear-cytoplasmic sex inheritance.

    PubMed Central

    Barr, Camille M.

    2004-01-01

    I investigated whether soil moisture affects relative fitness of females and hermaphrodites and sex ratio in a gynodioecious plant with nuclear-cytoplasmic sex inheritance. I contrast these results with those from species with strictly nuclear sex inheritance. I performed a manipulative watering experiment on seed fitness of the two sexes, and field studies measuring seed fitness and sex ratio as a function of soil moisture. In the dry site, watered hermaphrodites produced approximately twice as many seeds as unwatered hermaphrodites, with little treatment effect on female seed production. Over a natural soil moisture gradient, the ratio of female to hermaphrodite seed production was higher in dry than in wet sites. These data show that the seed fitness advantage of females is a function of soil moisture. Despite this, regression of soil moisture on the sex ratio of 23 populations was not significant. These results indicate a sex-dependent effect of soil moisture on resource allocation to seeds that does not translate into a strong effect on sex ratio. This is consistent with theory based on genomic conflict in which sex ratios are predicted to be only partly determined by fitness differences of the sexes. PMID:15347517

  3. A demographic model for sex ratio evolution and the effects of sex-biased offspring costs.

    PubMed

    Shyu, Esther; Caswell, Hal

    2016-03-01

    The evolution of the primary sex ratio, the proportion of male births in an individual's offspring production strategy, is a frequency-dependent process that selects against the more common sex. Because reproduction is shaped by the entire life cycle, sex ratio theory would benefit from explicitly two-sex models that include some form of life cycle structure. We present a demographic approach to sex ratio evolution that combines adaptive dynamics with nonlinear matrix population models. We also determine the evolutionary and convergence stability of singular strategies using matrix calculus. These methods allow the incorporation of any population structure, including multiple sexes and stages, into evolutionary projections. Using this framework, we compare how four different interpretations of sex-biased offspring costs affect sex ratio evolution. We find that demographic differences affect evolutionary outcomes and that, contrary to prior belief, sex-biased mortality after parental investment can bias the primary sex ratio (but not the corresponding reproductive value ratio). These results differ qualitatively from the widely held conclusions of previous models that neglect demographic structure. PMID:26900452

  4. Control of mammalian sex ratio by sexing sperm

    SciTech Connect

    Gledhill, B.L.

    1983-11-01

    Preselection of sex is discussed with emphasis on methods which have claimed success in separating X- and Y-chromosome-bearing sperm. Much of the recent experimental work in separating human X and Y sperm judges the success of enrichment solely by staining for the Y sperm with a quinacrine dye, which causes a bright fluorescence of the long arm of the Y chromosome. This method is questioned because the endpoint may be producing spurious results. Flow sorting is believed to be the first verified separation of mammalian sperm, but the sperm were nonviable. Flow cytometry can be used to quickly determine the success of other enrichment techniques. Bulk separation, as contrasted to separation based on determination of individual sperm characteristics, with 80% enrichment seems to be a reasonable future goal.

  5. Skewed sex ratios in India: "physician, heal thyself".

    PubMed

    Patel, Archana B; Badhoniya, Neetu; Mamtani, Manju; Kulkarni, Hemant

    2013-06-01

    Sex selection, a gender discrimination of the worst kind, is highly prevalent across all strata of Indian society. Physicians have a crucial role in this practice and implementation of the Indian Government's Pre-Natal Diagnostic Techniques Act in 1996 to prevent the misuse of ultrasound techniques for the purpose of prenatal sex determination. Little is known about family preferences, let alone preferences among families of physicians. We investigated the sex ratios in 946 nuclear families with 1,624 children, for which either one or both parents were physicians. The overall child sex ratio was more skewed than the national average of 914. The conditional sex ratios decreased with increasing number of previous female births, and a previous birth of a daughter in the family was associated with a 38 % reduced likelihood of a subsequent female birth. The heavily skewed sex ratios in the families of physicians are indicative of a deeply rooted social malady that could pose a critical challenge in correcting the sex ratios in India. PMID:23322380

  6. Maladaptive Sex Ratio Adjustment in the Invasive Brine Shrimp Artemia franciscana.

    PubMed

    Lievens, Eva J P; Henriques, Gil J B; Michalakis, Yannis; Lenormand, Thomas

    2016-06-01

    Sex allocation theory is often hailed as the most successful area of evolutionary theory due to its striking success as a predictor of empirical observations [1]. Most naturally occurring sex ratios can be explained by the principle of equal investment in the sexes [2-4] or by cases of "extraordinary" sex allocation [5]. Deviations from the expected sex ratio are often correlated with weak selection or low environmental predictability (e.g., [6, 7]); true cases of aberrant sex allocation are surprisingly rare [8]. Here, we present a case of long-lasting maladaptive sex allocation, which we discovered in invasive populations of the exclusively sexual brine shrimp Artemia franciscana. A. franciscana was introduced to Southern France roughly 500 generations ago [9]; since then, it has coexisted with the native asexual species Artemia parthenogenetica [10]. Although we expect A. franciscana to produce balanced offspring sex ratios, we regularly observed extremely male-biased sex ratios in invasive A. franciscana, which were significantly correlated to the proportion of asexuals in the overall population. We experimentally proved that both invasive- and native-range A. franciscana overproduced sons when exposed to excess females, without distinguishing between conspecific and asexual females. We conclude that A. franciscana adjust their offspring sex ratio in function of the adult sex ratio but are information limited in the presence of asexual females. Their facultative adjustment trait, which is presumably adaptive in their native range, has thus become maladaptive in the invasive range where asexuals occur. Despite this, it has persisted unchanged for hundreds of generations. PMID:27185556

  7. Does the Mother or Father Determine the Offspring Sex Ratio? Investigating the Relationship between Maternal Digit Ratio and Offspring Sex Ratio

    PubMed Central

    Kim, Tae Beom; Oh, Jin Kyu; Kim, Kwang Taek; Yoon, Sang Jin; Kim, Soo Woong

    2015-01-01

    Objective In mammals, high parental testosterone levels present around the time of conception are thought to skew offspring sex ratio toward sons. The second to fourth digit ratio (digit ratio) is now widely accepted as a negative correlate of prenatal testosterone. Thus, we investigated the association between digit ratio and offspring sex ratio. Methods A total of 508 Korean patients (257 males and 251 females) less than 60 years old who had one or more offspring were prospectively enrolled. The lengths of the 2nd and 4th digits of the right hand were measured by a single investigator using a digital vernier calliper. Next, the patients’ lifetime offspring birth sex ratios were investigated. Results Maternal (rather than paternal) digit ratio was significantly associated with the number of sons (r = -0.153, p = 0.015), number of daughters (r = 0.130, p = 0.039), and offspring sex ratio (r = -0.171, p = 0.007). And, the maternal digit ratio was a significant factor for predicting offspring sex ratio (B = -1.620, p = 0.008) on multiple linear regression analysis. The female patients with a lower digit ratio (< 0.95) were found to have a higher offspring sex ratio (0.609 versus 0.521, p = 0.046) compared to those with a higher digit ratio (≥ 0.95). Furthermore, females in the low digit ratio group have a probability 1.138 greater of having sons than females in the high digit ratio group. Conclusions Maternal digit ratio was negatively associated with offspring sex ratio. Females with a lower digit ratio were more likely to have more male offspring compared to those with a higher digit ratio. Thus, our results suggest that the sex of offspring might be more influenced by maternal rather than paternal factors. PMID:26575995

  8. The Trivers-Willard hypothesis: sex ratio or investment?

    PubMed

    Veller, Carl; Haig, David; Nowak, Martin A

    2016-05-11

    The Trivers-Willard hypothesis has commonly been considered to predict two things. First, that a mother in good condition should bias the sex ratio of her offspring towards males (if males exhibit greater variation in reproductive value). Second, that a mother in good condition should invest more per son than per daughter. These two predictions differ empirically, mechanistically and, as we demonstrate here, theoretically too. We construct a simple model of sex allocation that allows simultaneous analysis of both versions of the Trivers-Willard hypothesis. We show that the sex ratio version holds under very general conditions, being valid for a large class of male and female fitness functions. The investment version, on the other hand, is shown to hold only for a small subset of male and female fitness functions. Our results help to make sense of the observation that the sex ratio version is empirically more successful than the investment version. PMID:27170721

  9. Incubation temperature causes skewed sex ratios in a precocial bird.

    PubMed

    DuRant, Sarah E; Hopkins, William A; Carter, Amanda W; Kirkpatrick, Laila T; Navara, Kristin J; Hawley, Dana M

    2016-07-01

    Many animals with genetic sex determination are nonetheless capable of manipulating sex ratios via behavioral and physiological means, which can sometimes result in fitness benefits to the parent. Sex ratio manipulation in birds is not widely documented, and revealing the mechanisms for altered sex ratios in vertebrates remains a compelling area of research. Incubation temperature is a key component of the developmental environment for birds, but despite its well-documented effects on offspring phenotype it has rarely been considered as a factor in avian sex ratios. Using ecologically relevant manipulations of incubation temperature within the range 35.0-37.0°C, we found greater mortality of female embryos during incubation than males regardless of incubation temperature, and evidence that more female than male embryos die at the lowest incubation temperature (35.0°C). Our findings in conjunction with previous work in brush turkeys suggest incubation temperature is an important determinant of avian secondary sex ratios that requires additional study, and should be considered when estimating the impact of climate change on avian populations. PMID:27143750

  10. Where have all the females gone? Male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) in alpine lakes

    NASA Astrophysics Data System (ADS)

    Žibrat, U.; Brancelj, A.

    2009-04-01

    In populations with both males and females sex-ratio is one of the driving forces of population dynamics. It influences fecundity, inbreeding and social interactions. Sex-ratio is affected by several biotic and abiotic factors, either by selective killing of one sex or by inducing migrations. In alpine lakes of Triglav National Park, Slovenia, an extremely male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) was regularly observed since 1992. We analysed population dynamics and sex-ratio of A. alpinus in three alpine lakes (Jezero v Ledvicah, Rjavo jezero and Zgornje Kriško jezero) from Triglav National Park in Slovenia. In addition to seasonal dynamics we also researched long-term changes in sex-ratio (in a period of 11 years from autumn samples) as a result of increased air-temperature, and zooplankton diurnal vertical migrations. Adults of both sexes were found to appear at the same time in the water collumn with males prevailing throughout the season. A similar trend was found in copepodites CV. The percent of adult females began increasing in late summer, when there were no more copepodites and recrutation from copepodites CV to adults stopped, while male mortality increased. All cohorts of A. alpinus were found to perform diurnal vertical migrations. Both adult and CV females remained close to the bottom during the day and migrated vertically during the night. Results of the long-term study show no changes in sex-ratio in autumn.

  11. Dynamics of sex ratio and female unmatedness under haplodiploidy

    PubMed Central

    Gardner, Andy

    2014-01-01

    Haplodiploid sex determination allows unmated females to produce sons. Consequently, a scarcity of males may lead to a significant proportion of females remaining unmated, which may in turn give rise to a surfeit of males in the following generation. Stable oscillation of the sex ratio has been predicted by classic models, and it remains a puzzle as to why this is not observed in natural populations. Here, I investigate the dynamics of sex allocation over ecological and evolutionary timescales to assess the potential for sustained oscillation. I find that, whilst stable oscillation of the sex ratio is possible, the scope for such dynamical behavior is reduced if sex allocation strategies are evolutionary labile, especially if mated females may facultatively adjust their sex allocation according to the present availability of mating partners. My model, taken together with empirical estimates of female unmatedness in haplodiploid taxa, suggests that sustained oscillation of the sex ratio is implausible in natural populations. However, this phenomenon may be relevant to artificially introduced biological control agents. PMID:24967080

  12. Coital rates, sex-selective infanticide, and sex ratios at birth.

    PubMed

    James, W H

    1996-01-01

    The author of this short article comments on the suggestion by Brewis and Underwood, in their report on Micronesia, that the high sex ratios at birth were due to the high coital rates (greater than 108-110). First, in Australia, the reported sex ratio of births conceived in the first month of marriage from 1908 to 1967 was 109. Mean reported marital coital rates during the first month of marriage for the United States and England are estimated to be 20 per month. The average coital rate is higher among women who conceive. If the variation of sex ratios across societies were explained by coital rates alone, Micronesian coital rates would have to be much greater than 20 per month throughout couples' reproductive lives, and 3 times the averages in postindustrial countries. Such coital rates have not been substantiated; other reasons may account for the high sex ratios in Micronesia. Brewis and Underwood stated that they did not believe sex-selective infanticide was an explanation of the high sex ratios; this may have been based on current practices. Yet past practices of sex-selective infanticide could influence current sex ratios, given that there is mathematical evidence that genetics may influence the probability of producing a child of a particular sex. Therefore, the average current sex ratio at conception and birth of a population depends on: the magnitude of the genetic component of the Lexis variance (the reproductive-lifetime probability of a couple's producing a boy at each birth); and 2) the extent of the sex-selective infanticide in the past. The total extent of the Lexis variance, including its genetic component, is unknown. PMID:8909113

  13. Skewed Sex Ratios and Criminal Victimization in India

    PubMed Central

    South, Scott J.; Trent, Katherine; Bose, Sunita

    2014-01-01

    Although substantial research has explored the causes of India’s excessively masculine population sex ratio, few studies have examined the consequences of this surplus of males. We merge individual-level data from the 2004–2005 India Human Development Survey with data from the 2001 India population census to examine the association between the district-level male-to-female sex ratio at ages 15 to 39 and self-reports of victimization by theft, breaking and entering, and assault. Multilevel logistic regression analyses reveal positive and statistically significant albeit substantively modest effects of the district-level sex ratio on all three victimization risks. We also find that higher male-to-female sex ratios are associated with the perception that young unmarried women in the local community are frequently harassed. Household-level indicators of family structure, socioeconomic status, and caste, as well as areal indicators of women’s empowerment and collective efficacy, also emerge as significant predictors of self-reported criminal victimization and the perceived harassment of young women. The implications of these findings for India’s growing sex ratio imbalance are discussed. PMID:24682921

  14. Estimators of the Human Effective Sex Ratio Detect Sex Biases on Different Timescales

    PubMed Central

    Emery, Leslie S.; Felsenstein, Joseph; Akey, Joshua M.

    2010-01-01

    Determining historical sex ratios throughout human evolution can provide insight into patterns of genomic variation, the structure and composition of ancient populations, and the cultural factors that influence the sex ratio (e.g., sex-specific migration rates). Although numerous studies have suggested that unequal sex ratios have existed in human evolutionary history, a coherent picture of sex-biased processes has yet to emerge. For example, two recent studies compared human X chromosome to autosomal variation to make inferences about historical sex ratios but reached seemingly contradictory conclusions, with one study finding evidence for a male bias and the other study identifying a female bias. Here, we show that a large part of this discrepancy can be explained by methodological differences. Specifically, through reanalysis of empirical data, derivation of explicit analytical formulae, and extensive simulations we demonstrate that two estimators of the effective sex ratio based on population structure and nucleotide diversity preferentially detect biases that have occurred on different timescales. Our results clarify apparently contradictory evidence on the role of sex-biased processes in human evolutionary history and show that extant patterns of human genomic variation are consistent with both a recent male bias and an earlier, persistent female bias. PMID:21109223

  15. Hormonal and behavioral determinants of the secondary sex ratio.

    PubMed

    Martin, J F

    1995-01-01

    The timing of insemination relative to ovulation and the frequency of insemination appear prominently in analyses of variations in human secondary sex ratios. Explanations invoking these variables are shown to be inadequate. A new synthetic model of sex determination is proposed in which the sex of offspring is powerfully determined by the state of the cervical mucus. The cervical state is then shown to be a function of hormonal factors endogenous to the female in interaction with the effects of previous inseminations. PMID:8738548

  16. Persistent sex-by-environment effects on offspring fitness and sex-ratio adjustment in a wild bird population.

    PubMed

    Bowers, E Keith; Thompson, Charles F; Sakaluk, Scott K

    2015-03-01

    A major component of sex-allocation theory, the Trivers-Willard model (TWM), posits that sons and daughters are differentially affected by variation in the rearing environment. In many species, the amount of parental care received is expected to have differing effects on the fitness of males and females. When this occurs, the TWM predicts that selection should favour adjustment of the offspring sex ratio in relation to the expected fitness return from offspring. However, evidence for sex-by-environment effects is mixed, and little is known about the adaptive significance of producing either sex. Here, we test whether offspring sex ratios vary according to predictions of the TWM in the house wren (Troglodytes aedon, Vieillot). We also test the assumption of a sex-by-environment effect on offspring using two experiments, one in which we manipulated age differences among nestlings within broods, and another in which we held nestling age constant but manipulated brood size. As predicted, females with high investment ability overproduced sons relative to those with lower ability. Males were also overproduced early within breeding seasons. In our experiments, the body mass of sons was more strongly affected by the sibling-competitive environment and resource availability than that of daughters: males grew heavier than females when reared in good conditions but were lighter than females when in poor conditions. Parents rearing broods with 1:1 sex ratios were more productive than parents rearing broods biased more strongly towards sons or daughters, suggesting that selection favours the production of mixed-sex broods. However, differences in the condition of offspring as neonates persisted to adulthood, and their reproductive success as adults varied with the body mass of sons, but not daughters, prior to independence from parental care. Thus, selection should favour slight but predictable variations in the sex ratio in relation to the quality of offspring that parents are

  17. Persistent sex-by-environment effects on offspring fitness and sex-ratio adjustment in a wild bird population

    PubMed Central

    Bowers, E. Keith; Thompson, Charles F.; Sakaluk, Scott K.

    2014-01-01

    Summary A major component of sex-allocation theory, the Trivers-Willard Model (TWM), posits that sons and daughters are differentially affected by variation in the rearing environment. In many species, the amount of parental care received is expected to have differing effects on the fitness of males and females. When this occurs, the TWM predicts that selection should favour adjustment of the offspring sex ratio in relation to the expected fitness return from offspring. However, evidence for sex-by-environment effects is mixed and little is known about the adaptive significance of producing either sex. Here, we test whether offspring sex ratios vary according to predictions of the TWM in the house wren (Troglodytes aedon, Vieillot). We also test the assumption of a sex-by-environment effect on offspring using two experiments, one in which we manipulated age-differences among nestlings within broods, and another in which we held nestling age constant but manipulated brood size. As predicted, females with high investment ability over-produced sons relative to those with lower ability. Males were also over-produced early within breeding seasons. In our experiments, the body mass of sons was more strongly affected by the sibling-competitive environment and resource availability than that of daughters: males grew heavier than females when reared in good conditions but were lighter than females when in poor conditions. Parents rearing broods with 1:1 sex ratios were more productive than parents rearing broods biased more strongly towards sons or daughters, suggesting that selection favours the production of mixed-sex broods. However, differences in the condition of offspring as neonates persisted to adulthood, and their reproductive success as adults varied with the body mass of sons, but not daughters, prior to independence from parental care. Thus, selection should favour slight but predictable variations in the sex ratio in relation to the quality of offspring that

  18. Decline in sex ratio at birth after Kobe earthquake.

    PubMed

    Fukuda, M; Fukuda, K; Shimizu, T; Møller, H

    1998-08-01

    We investigated the possible association between the Kobe earthquake (January 1995) and the sex ratio among live-born infants after the catastrophe. A significant decline in the sex ratio (0.501) of Hyogo Prefecture in October 1995 was observed 9 months after the Kobe earthquake as compared with an expected value of 0.516 in the period from January 1993 to January 1996 (P = 0.04; one-tailed). Simultaneously, a reduction in fertility of approximately 6% was also observed, compared with the month of October 2 years previously. Thus, the acute stress resulting from a great natural catastrophe can be a cause of a low sex ratio at birth 9 months later. PMID:9756319

  19. Developmental mortality increases sex-ratio bias of a size-dimorphic bark beetle

    PubMed Central

    Lachowsky, Leanna E; Reid, Mary L

    2014-01-01

    1. Given sexual size dimorphism, differential mortality owing to body size can lead to sex-biased mortality, proximately biasing sex ratios. This mechanism may apply to mountain pine beetles, Dendroctonus ponderosae Hopkins, which typically have female-biased adult populations (2 : 1) with females larger than males. Smaller males could be more susceptible to stresses than larger females as developing beetles overwinter and populations experience high mortality. 2. Survival of naturally-established mountain pine beetles during the juvenile stage and the resulting adult sex ratios and body sizes (volume) were studied. Three treatments were applied to vary survival in logs cut from trees containing broods of mountain pine beetles. Logs were removed from the forest either in early winter, or in spring after overwintering below snow or after overwintering above snow. Upon removal, logs were placed at room temperature to allow beetles to complete development under similar conditions. 3. Compared with beetles from logs removed in early winter, mortality was higher and the sex ratio was more female-biased in overwintering logs. The bias increased with overwinter mortality. However, sex ratios were female-biased even in early winter, so additional mechanisms, other than overwintering mortality, contributed to the sex-ratio bias. Body volume varied little relative to sex-biased mortality, suggesting other size-independent causes of male-biased mortality. 4. Overwintering mortality is considered a major determinant of mountain pine beetle population dynamics. The disproportionate survival of females, who initiate colonisation of live pine trees, may affect population dynamics in ways that have not been previously considered. PMID:25400320

  20. Sex ratio estimation and survival analysis for Orthetrum coerulescens (Odonata, Libellulidae)

    USGS Publications Warehouse

    Kery, M.; Juillerat, L.

    2004-01-01

    There is controversy over whether uneven sex ratios observed in mature dragonfly populations are a mere artifact resulting from the higher observability of males. Previous studies have at best made indirect inference about sex ratios by analysis of survival or recapture rates. Here, we obtain direct estimates of sex ratio from capture?recapture data based on the Cormack?Jolly?Seber model. We studied Orthetrum coerulescens (Fabricius, 1798) at three sites in the Swiss Jura Mountains over an entire activity period. Recapture rates per 5-day interval were 3.5 times greater for males (0.67, SE 0.02) than for females (0.19, SE 0.02). At two sites, recapture rate increased over the season for males and was constant for females, and at one site it decreased with precipitation for both sexes. In addition, recapture rate was higher with higher temperature for males only. We found no evidence for higher male survival rates in any population. Survival per 5-day interval for both sexes was estimated to be 0.77 (95% CI 0.75?0.79) without significant site or time-specific variation. There were clear effects of temperature (positive) and precipitation (negative) on survival rate at two sites. Direct estimates of sex ratios were not significantly different from 1 for any time interval. Hence, the observed male-biased sex ratio in adult O. coerulescens was an artifact resulting from the better observability of males. The method presented in this paper is applicable to sex ratio estimation in any kind of animal.

  1. Sex ratio biases in termites provide evidence for kin selection.

    PubMed

    Kobayashi, Kazuya; Hasegawa, Eisuke; Yamamoto, Yuuka; Kawatsu, Kazutaka; Vargo, Edward L; Yoshimura, Jin; Matsuura, Kenji

    2013-01-01

    Inclusive fitness theory, also known as kin selection theory, is the most general expansion of Darwin's natural selection theory. It is supported by female-biased investment by workers in the social Hymenoptera where relatedness to sisters is higher than to brothers because of haplodiploidy. However, a strong test of the theory has proven difficult in diploid social insects because they lack such relatedness asymmetry. Here we show that kin selection can result in sex ratio bias in eusocial diploids. Our model predicts that allocation will be biased towards the sex that contributes more of its genes to the next generation when sex-asymmetric inbreeding occurs. The prediction matches well with the empirical sex allocation of Reticulitermes termites where the colony king can be replaced by a queen's son. Our findings open broad new avenues to test inclusive fitness theory beyond the well-studied eusocial Hymenoptera. PMID:23807025

  2. Distal femoral aspect ratios throughout childhood: an MRI study of normative data and sex comparisons.

    PubMed

    Schwarzkopf, Ran; Bauer, Andrea; Chaurasia, Avinash; Hall, Amber M; Zurakowski, David; Scott, Richard D

    2016-05-01

    The ratio of anteroposterior (AP) to medial-lateral (ML) dimensions of the distal femur in adults differs by sex. The average AP/ML dimension ratios are 0.82 for females and 0.79 for males. How and when this difference develops is not yet understood. In this study, the distal femoral dimensions and physeal development of 345 participants younger than 21 years of age were evaluated by MRI. Regression analysis indicated a significant increase in the AP/ML ratio with increasing age for both sexes. In girls, the ratio increased from 0.63 at ages 0-5 years to 0.76 at 15-20 years. In boys, the ratio increased from 0.61 to 0.73 over the same age groups. Female distal femur dimensions are narrower than that of males from birth. Throughout childhood, both sexes show gradual increases in AP/ML ratios. After closure of the physes, the AP/ML ratio in children approaches adult values, with females continuing to have relatively narrower dimensions than males. PMID:26895290

  3. Evidence of Self-correction of Child Sex Ratios in India: A District-Level Analysis of Child Sex Ratios From 1981 to 2011.

    PubMed

    Diamond-Smith, Nadia; Bishai, David

    2015-04-01

    Sex ratios in India have become increasingly imbalanced over the past decades. We hypothesize that when sex ratios become very uneven, the shortage of girls will increase girls' future value, leading sex ratios to self-correct. Using data on children under 5 from the last four Indian censuses, we examine the relationship between the sex ratio at one point in time and the change in sex ratio over the next 10 years by district. Fixed-effects models show that when accounting for unobserved district-level characteristics--including total fertility rate, infant mortality rate, percentage literate, percentage rural, percentage scheduled caste, percentage scheduled tribe, and a time trend variable--sex ratios are significantly negatively correlated with the change in sex ratio in the successive 10-year period. This suggests that self-corrective forces are at work on imbalanced sex ratios in India. PMID:25504536

  4. Abnormal sex ratios in human populations: Causes and consequences

    PubMed Central

    Hesketh, Therese; Xing, Zhu Wei

    2006-01-01

    In the absence of manipulation, both the sex ratio at birth and the population sex ratio are remarkably constant in human populations. Small alterations do occur naturally; for example, a small excess of male births has been reported to occur during and after war. The tradition of son preference, however, has distorted these natural sex ratios in large parts of Asia and North Africa. This son preference is manifest in sex-selective abortion and in discrimination in care practices for girls, both of which lead to higher female mortality. Differential gender mortality has been a documented problem for decades and led to reports in the early 1990s of 100 million “missing women” across the developing world. Since that time, improved health care and conditions for women have resulted in reductions in female mortality, but these advances have now been offset by a huge increase in the use of sex-selective abortion, which became available in the mid-1980s. Largely as a result of this practice, there are now an estimated 80 million missing females in India and China alone. The large cohorts of “surplus” males now reaching adulthood are predominantly of low socioeconomic class, and concerns have been expressed that their lack of marriageability, and consequent marginalization in society, may lead to antisocial behavior and violence, threatening societal stability and security. Measures to reduce sex selection must include strict enforcement of existing legislation, the ensuring of equal rights for women, and public awareness campaigns about the dangers of gender imbalance. PMID:16938885

  5. Do malaria parasites follow the algebra of sex ratio theory?

    PubMed

    Schall, Jos J

    2009-03-01

    The ratio of male to female gametocytes seen in infections of Plasmodium and related haemosporidian parasites varies substantially, both within and among parasite species. Sex ratio theory, a mainstay of evolutionary biology, accounts for this variation. The theory provides an algebraic solution for the optimal sex ratio that will maximize parasite fitness. A crucial term in this solution is the probability of selfing by clone-mates within the vector (based on the clone number and their relative abundance). Definitive tests of the theory have proven elusive because of technical challenges in measuring clonal diversity within infections. Newly developed molecular methods now provide opportunities to test the theory with an exquisite precision. PMID:19201653

  6. Going All In: Unfavorable Sex Ratios Attenuate Choice Diversification.

    PubMed

    Ackerman, Joshua M; Maner, Jon K; Carpenter, Stephanie M

    2016-06-01

    When faced with risky decisions, people typically choose to diversify their choices by allocating resources across a variety of options and thus avoid putting "all their eggs in one basket." The current research revealed that this tendency is reversed when people face an important cue to mating-related risk: skew in the operational sex ratio, or the ratio of men to women in the local environment. Counter to the typical strategy of choice diversification, findings from four studies demonstrated that the presence of romantically unfavorable sex ratios (those featuring more same-sex than opposite-sex individuals) led heterosexual people to diversify financial resources less and instead concentrate investment in high-risk/high-return options when making lottery, stock-pool, retirement-account, and research-funding decisions. These studies shed light on a key process by which people manage risks to mating success implied by unfavorable interpersonal environments. These choice patterns have important implications for mating behavior as well as other everyday forms of decision making. PMID:27056976

  7. Suburbanization, estrogen contamination, and sex ratio in wild amphibian populations.

    PubMed

    Lambert, Max R; Giller, Geoffrey S J; Barber, Larry B; Fitzgerald, Kevin C; Skelly, David K

    2015-09-22

    Research on endocrine disruption in frog populations, such as shifts in sex ratios and feminization of males, has predominantly focused on agricultural pesticides. Recent evidence suggests that suburban landscapes harbor amphibian populations exhibiting similar levels of endocrine disruption; however the endocrine disrupting chemical (EDC) sources are unknown. Here, we show that sex ratios of metamorphosing frogs become increasingly female-dominated along a suburbanization gradient. We further show that suburban ponds are frequently contaminated by the classical estrogen estrone and a variety of EDCs produced by plants (phytoestrogens), and that the diversity of organic EDCs is correlated with the extent of developed land use and cultivated lawn and gardens around a pond. Our work also raises the possibility that trace-element contamination associated with human land use around suburban ponds may be contributing to the estrogenic load within suburban freshwaters and constitutes another source of estrogenic exposure for wildlife. These data suggest novel, unexplored pathways of EDC contamination in human-altered environments. In particular, we propose that vegetation changes associated with suburban neighborhoods (e.g., from forests to lawns and ornamental plants) increase the distribution of phytoestrogens in surface waters. The result of frog sex ratios varying as a function of human land use implicates a role for environmental modulation of sexual differentiation in amphibians, which are assumed to only have genetic sex determination. Overall, we show that endocrine disruption is widespread in suburban frog populations and that the causes are likely diverse. PMID:26372955

  8. Suburbanization, estrogen contamination, and sex ratio in wild amphibian populations

    PubMed Central

    Lambert, Max R.; Giller, Geoffrey S. J.; Barber, Larry B.; Fitzgerald, Kevin C.; Skelly, David K.

    2015-01-01

    Research on endocrine disruption in frog populations, such as shifts in sex ratios and feminization of males, has predominantly focused on agricultural pesticides. Recent evidence suggests that suburban landscapes harbor amphibian populations exhibiting similar levels of endocrine disruption; however the endocrine disrupting chemical (EDC) sources are unknown. Here, we show that sex ratios of metamorphosing frogs become increasingly female-dominated along a suburbanization gradient. We further show that suburban ponds are frequently contaminated by the classical estrogen estrone and a variety of EDCs produced by plants (phytoestrogens), and that the diversity of organic EDCs is correlated with the extent of developed land use and cultivated lawn and gardens around a pond. Our work also raises the possibility that trace-element contamination associated with human land use around suburban ponds may be contributing to the estrogenic load within suburban freshwaters and constitutes another source of estrogenic exposure for wildlife. These data suggest novel, unexplored pathways of EDC contamination in human-altered environments. In particular, we propose that vegetation changes associated with suburban neighborhoods (e.g., from forests to lawns and ornamental plants) increase the distribution of phytoestrogens in surface waters. The result of frog sex ratios varying as a function of human land use implicates a role for environmental modulation of sexual differentiation in amphibians, which are assumed to only have genetic sex determination. Overall, we show that endocrine disruption is widespread in suburban frog populations and that the causes are likely diverse. PMID:26372955

  9. The ecological and evolutionary drivers of female-biased sex ratios: two-sex models of perennial seagrasses.

    PubMed

    Shelton, Andrew Olaf

    2010-03-01

    Among sexually reproducing species, differences between the sexes within species are ubiquitous. Despite the clear effect of sex differences on sex ratios and population growth rates, demographic models rarely consider both sexes explicitly. Here I explore the causes of extreme female-biased sex ratios in two marine angiosperms (Phyllospadix spp.). Using demographic data, I develop two-sex matrix projection models to assess the magnitude of demographic differences necessary to generate observed sex ratios and the consequences of sex differences for population growth rates. I demonstrate that small sex differences in survival can generate biased sex ratios, but the importance of sexual reproduction differs markedly between species. Even in the absence of a direct trade-off between sexual and asexual reproduction, the presence of two reproductive modes affects both the importance of sex and the sex-ratio bias. Using sensitivity analyses, I quantify the contribution of shared and sex-specific vital rates and show that until males become rare, the sensitivity of sex-specific vital rates is small relative to that of shared vital rates. I demonstrate that placing sex differences in the context of a demographic model that includes biologically motivated life-history trade-offs can explain the maintenance of sex-specific life histories and the persistence of skewed sex ratios. PMID:20109068

  10. Transgenerational sex determination: the embryonic environment experienced by a male affects offspring sex ratio

    PubMed Central

    Warner, Daniel A.; Uller, Tobias; Shine, Richard

    2013-01-01

    Conditions experienced during embryonic development can have lasting effects, even carrying across generations. Most evidence for transgenerational effects comes from studies of female mammals, with much less known about egg-laying organisms or paternally-mediated effects. Here we show that offspring sex can be affected by the incubation temperature its father experiences years earlier. We incubated eggs of an Australian lizard with temperature-dependent sex determination under three thermal regimes; some eggs were given an aromatase inhibitor to produce sons at temperatures that usually produce only daughters. Offspring were raised to maturity and freely interbred within field enclosures. After incubating eggs of the subsequent generation and assigning parentage, we found that the developmental temperature experienced by a male significantly influences the sex of his future progeny. This transgenerational effect on sex ratio may reflect an epigenetic influence on paternally-inherited DNA. Clearly, sex determination in reptiles is far more complex than is currently envisaged. PMID:24048344

  11. Sex ratio and reproductive activity of benthic copepods in bathyal Sagami Bay (1430 m), central Japan

    NASA Astrophysics Data System (ADS)

    Shimanaga, Motohiro; Shirayama, Yoshihisa

    2003-04-01

    Sex ratios and reproductive activity of benthic copepod assemblages were investigated at the bathyal site (depth 1430 m) in Sagami Bay, central Japan. The ratio of adult females to adult males was approximately 3.5:1, significantly different from 1:1, although this parameter did not show a seasonal pattern. On the other hand, the percentage of ovigerous females among adult females and the ratio of nauplii to total copepods appeared to fluctuate seasonally in 1997 and 1998. Statistical tests, however, could not detect significant difference in either parameter. We discuss the possibility that the reproductive activity of copepods was enhanced by the increased supply of fresh phytodetritus to the sea floor.

  12. Sex Suffers for Younger Adults After Heart Attack

    MedlinePlus

    ... 160722.html Sex Suffers for Younger Adults After Heart Attack Lack of interest a complaint of many women ... WEDNESDAY, Aug. 31, 2016 (HealthDay News) -- After a heart attack, many younger adults experience sexual difficulties -- and women ...

  13. SEX-RATIO MEIOTIC DRIVE AND INTERSPECIFIC COMPETITION

    PubMed Central

    Unckless, Robert L.; Clark, Andrew G.

    2014-01-01

    It has long been known that processes occurring within a species may impact the interactions between species. For example, since competitive ability is sensitive to parameters including reproductive rate, carrying capacity and competition efficiency, the outcome of interspecific competition may be influenced by any process that alters these attributes. While several such scenarios have been discussed, the influence of selfish genetic elements within one species on competition between species has not received theoretical treatment. We show that, with strong competition, sex-ratio meiotic drive systems can result in a significant shift in community composition because the effective birth rate in the population may be increased by a female-biased sex-ratio. Using empirical data we attempt to estimate the magnitude of this effect in several Drosophila species. We infer that meiotic drive elements, selfish genetic elements within species, can provide a substantial competitive advantage to that species within a community. PMID:24835887

  14. Partnership status and the human sex ratio at birth.

    PubMed Central

    Norberg, Karen

    2004-01-01

    If two-parent care has different consequences for the reproductive success of sons and daughters, then natural selection may favour adjustment of the sex ratio at birth according to circumstances that forecast later family structure. In humans, this partnership-status hypothesis predicts fewer sons among extra-pair conceptions, but the rival 'attractiveness' hypothesis predicts more sons among extra-pair conceptions, and the 'fixed-phenotype' hypothesis predicts a constant probability of having a son, regardless of partnership status. In a sample of 86 436 human births pooled from five US population-based surveys, I found 51.5% male births reported by respondents who were living with a spouse or partner before the child's conception or birth, and 49.9% male births reported by respondents who were not (chi(2)=16.77 d.f.=1 p<0.0001). The effect was not explained by paternal bias against daughters, by parental age, education, income, ethnicity or by year of observation, and was larger when comparisons were made between siblings. To my knowledge, this is the first direct evidence for conditional adjustment of the sex ratio at birth in humans, and could explain the recent decline in the sex ratio at birth in some developed countries. PMID:15556894

  15. Preconception maternal polychlorinated biphenyl concentrations and the secondary sex ratio

    SciTech Connect

    Taylor, Kira C.; Jackson, Leila W.; Lynch, Courtney D.; Kostyniak, Paul J.; Buck Louis, Germaine M. . E-mail: louisg@mail.nih.gov

    2007-01-15

    The secondary sex ratio is the ratio of male to female live births and historically has ranged from 102 to 106 males to 100 females. Temporal declines have been reported in many countries prompting authors to hypothesize an environmental etiology. Blood specimens were obtained from 99 women aged 24-34 prior to attempting pregnancy and quantified for 76 polychlorinated biphenyl (PCB) congeners using dual column gas chromatography with electron capture detection. Women were prospectively followed until pregnancy or 12 cycles of trying. The odds of a male birth for three PCB groupings (total, estrogenic, anti-estrogenic) controlling for maternal characteristics were estimated using logistic regression. Among the 50 women with live births and PCB data, 26 female and 24 male infants were born (ratio 0.92). After adjusting for age and body mass index, odds of a male birth were elevated among women in the second (OR=1.29) and third (OR=1.48) tertiles of estrogenic PCBs; odds (OR=0.70) were reduced among women in the highest tertile of anti-estrogenic PCBs. All confidence intervals included one. The direction of the odds ratios in this preliminary study varied by PCB groupings, supporting the need to study specific PCB patterns when assessing environmental influences on the secondary sex ratio.

  16. Serial monogamy and sex ratio bias in Nazca boobies.

    PubMed

    Maness, Terri J; Anderson, David J

    2007-08-22

    Biased operational sex ratios (OSRs) can drive sexual selection on members of the over-represented sex via competition for mates, causing higher variance and skew in reproductive success (RS) among them if an individual's quality is a persistent characteristic. Alternatively, costs of reproduction may degrade breeding performance, creating the opportunity for members of the limiting sex to switch mates adaptively, effectively homogenizing variance and skew in RS among the sex in excess. We tested these two contrasting models in a male-biased population of the Nazca booby (Sula granti) with demonstrated costs of reproduction with data on total RS over a 14-year period. Variances and skews in RS were similar, and males changed from breeder to non-breeder more frequently than females. Under the persistent individual quality model, females should mate only with high quality males, and non-breeding males should seldom enter the breeding pool, yet 45% of non-breeding males (re)entered the breeding pool each year on average. Many Nazca booby females apparently exchange a depleted male for a new mate from the pool of current non-breeder males. Our evidence linking serial monogamy to costs of reproduction is novel and suggests selection on female mating preferences based on an interaction between at least two life-history components (OSR and reproductive effort). PMID:17567557

  17. Genetic architecture of sex determination in fish: applications to sex ratio control in aquaculture

    PubMed Central

    Martínez, Paulino; Viñas, Ana M.; Sánchez, Laura; Díaz, Noelia; Ribas, Laia; Piferrer, Francesc

    2014-01-01

    Controlling the sex ratio is essential in finfish farming. A balanced sex ratio is usually good for broodstock management, since it enables to develop appropriate breeding schemes. However, in some species the production of monosex populations is desirable because the existence of sexual dimorphism, primarily in growth or first time of sexual maturation, but also in color or shape, can render one sex more valuable. The knowledge of the genetic architecture of sex determination (SD) is convenient for controlling sex ratio and for the implementation of breeding programs. Unlike mammals and birds, which show highly conserved master genes that control a conserved genetic network responsible for gonad differentiation (GD), a huge diversity of SD mechanisms has been reported in fish. Despite theory predictions, more than one gene is in many cases involved in fish SD and genetic differences have been observed in the GD network. Environmental factors also play a relevant role and epigenetic mechanisms are becoming increasingly recognized for the establishment and maintenance of the GD pathways. Although major genetic factors are frequently involved in fish SD, these observations strongly suggest that SD in this group resembles a complex trait. Accordingly, the application of quantitative genetics combined with genomic tools is desirable to address its study and in fact, when applied, it has frequently demonstrated a multigene trait interacting with environmental factors in model and cultured fish species. This scenario has notable implications for aquaculture and, depending upon the species, from chromosome manipulation or environmental control techniques up to classical selection or marker assisted selection programs, are being applied. In this review, we selected four relevant species or fish groups to illustrate this diversity and hence the technologies that can be used by the industry for the control of sex ratio: turbot and European sea bass, two reference species of

  18. Effects of perchlorate bioaccumulation on Spodoptera litura growth and sex ratio.

    PubMed

    Qin, Junhao; Shu, Yinghua; Li, Yongjun; He, Hongzhi; Li, Huashou

    2016-05-01

    Perchlorate (ClO4 (-)) pollution is widespread in the natural environment, but the effects of ClO4 (-) on the terrestrial insects are rarely studied. Here, when phytophagous insect Spodoptera litura larvae were fed on the diets with different ClO4 (-) concentrations, changes in their life-history traits were recorded; ClO4 (-) accumulations in feces and insect body were detected. The results demonstrated that ClO4 (-) bioaccumulation in insect at the different developmental stages was ranked in the order: adults > pupae > the 4th > 5th > 6th instar larvae. Besides, ClO4 (-) accumulations in the feces were ranked in the order: the 6th > 5th > 4th instar larvae. The ClO4 (-) accumulations in female pupae and adults were significantly higher than that in males. ClO4 (-) bioaccumulation in insect prolonged larval development time and caused a skewed sex ratio (the percentage of males at metamorphosis significantly decreased) under 100 to 200 mg ClO4 (-)/kg treatment. Therefore, ClO4 (-) accumulations in S. litura body presented developmental stage-, sex-specific pattern, and the sex-specific ClO4 (-) accumulations resulted in difference of sex ratio. These effects were observed at concentrations reported in natural environments contaminated with ClO4 (-), suggesting that this contaminant may pose a threat to the normal development and growth of this insect species. PMID:26810791

  19. Hybridization and regional sex ratios in Nemophila menziesii.

    PubMed

    Barr, C M

    2004-07-01

    I tested whether a region of high female frequencies in the gynodioecious plant, Nemophila menziesii, may be due to hybridization between regionally distributed populations with different corolla colours. I crossed plants in the greenhouse from populations with different corolla colours and found that hybrid crosses yielded higher frequencies of females than within-colour crosses. In the field, I found that populations with high female frequencies had intermediate mean corolla colours and higher variance in corolla colour, two traits suggesting hybridization. Nemophila menziesii has nuclear-cytoplasmic sex inheritance, thus if populations with different corolla colours are fixed for different male-sterile cytoplasms and matching nuclear restorer alleles, hybridization between populations with different corolla colour should yield high frequencies of females. Two populations that are all hermaphroditic in the field segregated females in hybrid crosses suggesting that field populations may contain sex ratio distorters but appear undistorted, a prediction of genomic conflict theory. PMID:15271078

  20. The Effect of Climate Fluctuation on Chimpanzee Birth Sex Ratio

    PubMed Central

    Kühl, Hjalmar S.; N'Guessan, Antoine; Riedel, Julia; Metzger, Sonja; Deschner, Tobias

    2012-01-01

    Climate and weather conditions, such as the North Atlantic Oscillation, precipitation and temperature influence the birth sex ratio (BSR) of various higher latitude species, including deer, elephant seals or northern human populations. Although, tropical regions show only little variation in temperature, climate and weather conditions can fluctuate with consequences for phenology and food resource availability. Here, we evaluate, whether the BSR of chimpanzees, inhabiting African tropical forests, is affected by climate fluctuations as well. Additionally, we evaluate, if variation in consumption of a key food resource with high nutritional value, Coula edulis nuts, is linked to both climate fluctuations and variation in BSR. We use long-term data from two study groups located in Taï National Park, Côte d'Ivoire to assess the influence of local weather conditions and the global climate driver El Niño Southern Oscillation (ENSO) on offspring sex. Côte d'Ivoire has experienced considerable climate variation over the last decades, with increasing temperature and declining precipitation. For both groups we find very similar time windows around the month of conception, in which offspring sex is well predicted by ENSO, with more males following low ENSO values, corresponding to periods of high rainfall. Furthermore, we find that the time spent cracking and feeding on Coula nuts is strongly influenced by climate conditions. Although, some of our analysis suggest that a higher proportion of males is born after periods with higher nut consumption frequency, we cannot conclude decisively at this point that nut consumption may influence shifts in BSR. All results combined suggest that also chimpanzees may experience climate related shifts in offspring sex ratios as response to climate fluctuation. PMID:22563387

  1. Arachidonic Acid Enhances Reproduction in Daphnia magna and Mitigates Changes in Sex Ratios Induced by Pyriproxyfen

    PubMed Central

    Ginjupalli, Gautam K.; Gerard, Patrick D.; Baldwin, William S.

    2016-01-01

    Arachidonic acid (AA) is one of only two unsaturated fatty acids retained in the ovaries of crustaceans, and an inhibitor of HR97g, a nuclear receptor expressed in adult ovaries. We hypothesized that as a key fatty acid, AA may be associated with reproduction and potentially environmental sex determination in Daphnia. Reproduction assays with AA indicate that it alters female/male sex ratios by increasing female production. This reproductive effect only occurred during a restricted P. subcapitata diet. Next, we tested whether enriching a poorer algal diet (C. vulgaris) with AA enhances overall reproduction and sex ratios. AA enrichment of a C. vulgaris diet also enhances fecundity at 1.0 and 4.0μM by 30–40% in the presence and absence of pyriproxyfen. This indicates that AA is crucial in reproduction regardless of environmental sex determination. Furthermore, our data indicates that P. subcapitata may provide a threshold concentration of AA needed for reproduction. Diet switch experiments from P. subcapitata to C. vulgaris mitigate some but not all of AA’s effects when compared to a C. vulgaris only diet, suggesting that some AA provided by P. subcapitata is retained. In summary, AA supplementation increases reproduction and represses pyriproxyfen-induced environmental sex determination in D. magna in restricted diets. A diet rich in AA may provide protection from some reproductive toxicants such as the juvenile hormone agonist, pyriproxyfen. PMID:25393616

  2. Back-casting sociality in extinct species: new perspectives using mass death assemblages and sex ratios.

    PubMed Central

    Berger, J; Dulamtseren, S; Cain, S; Enkkhbileg, D; Lichtman, P; Namshir, Z; Wingard, G; Reading, R

    2001-01-01

    Despite 150 years of interest in the ecology of dinosaurs, mammoths, proto-hominids and other extinct vertebrates, a general framework to recreate patterns of sociality has been elusive. Based on our recent discovery of a contemporary heterospecific mass death assemblage in the Gobi Desert (Mongolia), we fit predictions about gender-specific associations and group living in extant ungulates to extinct ones. We relied on comparative data on sex-ratio variation and body-size dimorphism, basing analyses on 38 additional mass mortality sites from Asia, Africa, Europe and North America that span 50 million years. Both extant and extinct species died in aggregations with biased adult sex ratios, but the skew (from 1:1) was greater for extinct dimorphic taxa, suggesting that sociality in these extinct species can be predicted from spatial and demographic traits of extant ones. However, extinct rhinos, horses and zebras were inconsistent with predictions about adult sex ratios, which underscores the inherent difficulty in backcasting historic patterns to some monomorphic taxa. These findings shed light not only on the sociality of extinct species but provide a sound, although limited, footing for interpretation of modern death assemblages within the context of the emerging science of taphonomy and palaeobehaviour. PMID:11209882

  3. Skewed birth sex ratio and premature mortality in elephants.

    PubMed

    Saragusty, Joseph; Hermes, Robert; Göritz, Frank; Schmitt, Dennis L; Hildebrandt, Thomas B

    2009-10-01

    Sex allocation theories predict equal offspring number of both sexes unless differential investment is required or some competition exists. Left undisturbed, elephants reproduce well and in approximately even numbers in the wild. We report an excess of males are born and substantial juvenile mortality occurs, perinatally, in captivity. Studbook data on captive births (CB, n=487) and premature deaths (PD, <5 years of age; n=164) in Asian and African elephants in Europe and North America were compared with data on Myanmar timber (Asian) elephants (CB, n=3070; PD, n=738). Growth in CB was found in three of the captive populations. A significant excess of male births occurred in European Asian elephants (ratio: 0.61, P=0.044) and in births following artificial insemination (0.83, P=0.003), and a numerical inclination in North American African elephants (0.6). While juvenile mortality in European African and Myanmar populations was 21-23%, it was almost double (40-45%) in all other captive populations. In zoo populations, 68-91% of PD were within 1 month of birth with stillbirth and infanticide being major causes. In Myanmar, 62% of juvenile deaths were at >6 months with maternal insufficient milk production, natural hazards and accidents being the main causes. European Asian and Myanmar elephants PD was biased towards males (0.71, P=0.024 and 0.56, P<0.001, respectively). The skewed birth sex ratio and high juvenile mortality hinder efforts to help captive populations become self-sustaining. Efforts should be invested to identify the mechanism behind these trends and seek solutions for them. PMID:19058933

  4. Sex allocation and secondary sex ratio in Cuban boa (Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters.

    PubMed

    Frynta, Daniel; Vejvodová, Tereza; Šimková, Olga

    2016-06-01

    Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (∼200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes. PMID:27216175

  5. Sex allocation and secondary sex ratio in Cuban boa ( Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters

    NASA Astrophysics Data System (ADS)

    Frynta, Daniel; Vejvodová, Tereza; Šimková, Olga

    2016-06-01

    Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (˜200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes.

  6. Association of Educational Level and Child Sex Ratio in Rural and Urban India

    ERIC Educational Resources Information Center

    Inchani, Lisa R.; Lai, Dejian

    2008-01-01

    Utilizing data from the Census of India, this study compared child sex ratio in rural and urban regions of India and analyzed whether the child sex ratio was associated with mother's education level. The child sex ratios in the rural and urban regions throughout India were analyzed using the two-sample and paired Student's t-test. Further, the…

  7. Long-term trends of bloater (Coregonus hoyi) recruitment in Lake Michigan: evidence for the effect of sex ratio

    USGS Publications Warehouse

    Bunnell, David B.; Madenjian, Charles P.; Croley, Thomas E., II

    2006-01-01

    Long-term population trends are generally explained by factors extrinsic (e.g., climate, predation) rather than intrinsic (e.g., genetics, maternal effects) to the population. We sought to understand the long-term population dynamics of an important native Lake Michigan prey fish, the bloaterCoregonus hoyi. Over a 38-year time series, three 10- to 15-year phases occurred (poor, excellent, and then poor recruitment) without high interannual variability within a particular phase. We used dynamic linear models to determine whether extrinsic (winter and spring temperature, alewife predator densities) or intrinsic factors (population egg production, adult condition, adult sex ratio) explained variation in recruitment. Models that included population egg production, sex ratio, winter and spring temperature, and adult bloater condition explained the most variation. Of these variables, sex ratio, which ranged from 47% to 97% female across the time series, consistently had the greatest effect: recruitment declined with female predominance. Including biomass of adult alewife predators in the models did not explain additional variation. Overall our results indicated that bloater recruitment is linked to its sex ratio, but understanding the underlying mechanisms will require additional efforts.

  8. Sex Differences in the Longitudinal Prediction of Adult Personality.

    ERIC Educational Resources Information Center

    Sutton-Smith, B.; Rosenberg, B. G.

    This paper deals with two sets of data-one that fails to find any long-term sex differences in adults, and another which seems to find such differences. The Berkeley Guidance Study offers longitudinal data in which no variables differentiate between the two sexes at all age levels. From these results, the authors conclude that the normal course of…

  9. The high sex ratio in China: what do the Chinese think?

    PubMed

    Shou, C; Wang, L; Zheng, W J; Zhou, X D; Li, L; Hesketh, T

    2012-01-01

    High sex ratios are well documented in many Asian countries, including China. This study was conducted in three Chinese provinces to explore awareness of the high sex ratios and its effects. Questionnaires were completed by 7435 respondents; 46% were urban and 53% were female. Sixty-four per cent were aware of the high sex ratio, and the majority were able to identify a range of consequences both for society and for unmarried men. These high levels of awareness of the negative impacts of high sex ratios should ultimately help to reduce the sex ratio at birth. PMID:22220305

  10. Steinernema feltiae Intraspecific Variability: Infection Dynamics and Sex-Ratio

    PubMed Central

    Campos-Herrera, Raquel; Gutiérrez, Carmen

    2014-01-01

    Entomopathogenic nematodes (EPNs) from the Heterorhabditidae and Steinernematidae families are well-known biocontrol agents against numerous insect pests. The infective juveniles (IJs) are naturally occurring in the soil and their success in locating and penetrating the host will be affected by extrinsic/intrinsic factors that modulate their foraging behavior. Characterizing key traits in the infection dynamics of EPNs is critical for establishing differentiating species abilities to complete their life cycles and hence, their long-term persistence, in different habitats. We hypothesized that phenotypic variation in traits related to infection dynamics might occur in populations belonging to the same species. To assess these intraspecific differences, we evaluated the infection dynamics of 14 populations of Steinernema feltiae in two experiments measuring penetration and migration in sand column. Intraspecific variability was observed in the percentage larval mortality, time to kill the insect, penetration rate, and sex-ratio in both experiments (P < 0.01). Larval mortality and nematode penetration percentage were lower in migration experiments than in penetration ones in most of the cases. The sex-ratio was significantly biased toward female-development dominance (P < 0.05). When the populations were grouped by habitat of recovery (natural areas, crop edge, and agricultural groves), nematodes isolated in natural areas exhibited less larval mortality and penetration rates than those from some types of agricultural associated soils, suggesting a possible effect of the habitat on the phenotypic plasticity. This study reinforces the importance of considering intraspecific variability when general biological and ecological questions are addressed using EPNs. PMID:24644369

  11. Steinernema feltiae Intraspecific Variability: Infection Dynamics and Sex-Ratio.

    PubMed

    Campos-Herrera, Raquel; Gutiérrez, Carmen

    2014-03-01

    Entomopathogenic nematodes (EPNs) from the Heterorhabditidae and Steinernematidae families are well-known biocontrol agents against numerous insect pests. The infective juveniles (IJs) are naturally occurring in the soil and their success in locating and penetrating the host will be affected by extrinsic/intrinsic factors that modulate their foraging behavior. Characterizing key traits in the infection dynamics of EPNs is critical for establishing differentiating species abilities to complete their life cycles and hence, their long-term persistence, in different habitats. We hypothesized that phenotypic variation in traits related to infection dynamics might occur in populations belonging to the same species. To assess these intraspecific differences, we evaluated the infection dynamics of 14 populations of Steinernema feltiae in two experiments measuring penetration and migration in sand column. Intraspecific variability was observed in the percentage larval mortality, time to kill the insect, penetration rate, and sex-ratio in both experiments (P < 0.01). Larval mortality and nematode penetration percentage were lower in migration experiments than in penetration ones in most of the cases. The sex-ratio was significantly biased toward female-development dominance (P < 0.05). When the populations were grouped by habitat of recovery (natural areas, crop edge, and agricultural groves), nematodes isolated in natural areas exhibited less larval mortality and penetration rates than those from some types of agricultural associated soils, suggesting a possible effect of the habitat on the phenotypic plasticity. This study reinforces the importance of considering intraspecific variability when general biological and ecological questions are addressed using EPNs. PMID:24644369

  12. A female-biased sex ratio reduces the twofold cost of sex.

    PubMed

    Kobayashi, Kazuya; Hasegawa, Eisuke

    2016-01-01

    The evolution of sexual reproduction remains a fascinating enigma in biology. Theoretically, populations of sexual organisms investing half of their resources into producing male offspring that don't contribute to reproduction should grow at only half the rate of their asexual counterparts. This demographic disadvantage due to male production is known as the twofold cost of sex. However, the question of whether this cost is truly twofold for sexual females remains unanswered. The cost of producing males should decrease when the number of male offspring is reduced. Here, we report a case where the cost of males is actually less than twofold. By measuring the numbers of sexual strain coexisting with asexual strain among thrips, our survey revealed that the sexual strain showed female-biased sex ratios and that the relative frequency of sexual strain is negatively correlated with the proportion of males in the sexual strain. Using computer simulations, we confirmed that a female-biased sex ratio evolves in sexual individuals due to the coexistence of asexual individuals. Our results demonstrate that there is a cost of producing males that depends on the number of males. We therefore conclude that sexual reproduction can evolve with far fewer benefits than previously assumed. PMID:27035400

  13. A female-biased sex ratio reduces the twofold cost of sex

    PubMed Central

    Kobayashi, Kazuya; Hasegawa, Eisuke

    2016-01-01

    The evolution of sexual reproduction remains a fascinating enigma in biology. Theoretically, populations of sexual organisms investing half of their resources into producing male offspring that don’t contribute to reproduction should grow at only half the rate of their asexual counterparts. This demographic disadvantage due to male production is known as the twofold cost of sex. However, the question of whether this cost is truly twofold for sexual females remains unanswered. The cost of producing males should decrease when the number of male offspring is reduced. Here, we report a case where the cost of males is actually less than twofold. By measuring the numbers of sexual strain coexisting with asexual strain among thrips, our survey revealed that the sexual strain showed female-biased sex ratios and that the relative frequency of sexual strain is negatively correlated with the proportion of males in the sexual strain. Using computer simulations, we confirmed that a female-biased sex ratio evolves in sexual individuals due to the coexistence of asexual individuals. Our results demonstrate that there is a cost of producing males that depends on the number of males. We therefore conclude that sexual reproduction can evolve with far fewer benefits than previously assumed. PMID:27035400

  14. Sex Ratio Estimations of Loggerhead Sea Turtle Hatchlings at Kuriat Islands, Tunisia: Can Minor Nesting Sites Contribute to Compensate Globally Female-Biased Sex Ratio?

    PubMed Central

    Bradai, Mohamed Nejmeddine

    2014-01-01

    Hatchling sex ratios in the loggerhead turtle Caretta caretta were estimated by placing electronic temperature recorders in seven nests at Kuriat islands (Tunisia) during the 2013 nesting season. Based on the mean temperatures during the middle third of the incubation period, and on incubation duration, the sex ratio of hatchlings at Kuriat islands was highly male-biased. Presently, the majority of hatchling sex ratio studies are focused on major nesting areas, whereby the sex ratios are universally believed to be heavily female-biased. Here we present findings from a minor nesting site in the Mediterranean, where the hatchling sex ratio was found to be male-biased, suggesting a potential difference between major and minor nesting sites. PMID:25379528

  15. Sex ratio estimations of loggerhead sea turtle hatchlings at Kuriat islands, Tunisia: can minor nesting sites contribute to compensate globally female-biased sex ratio?

    PubMed

    Jribi, Imed; Bradai, Mohamed Nejmeddine

    2014-01-01

    Hatchling sex ratios in the loggerhead turtle Caretta caretta were estimated by placing electronic temperature recorders in seven nests at Kuriat islands (Tunisia) during the 2013 nesting season. Based on the mean temperatures during the middle third of the incubation period, and on incubation duration, the sex ratio of hatchlings at Kuriat islands was highly male-biased. Presently, the majority of hatchling sex ratio studies are focused on major nesting areas, whereby the sex ratios are universally believed to be heavily female-biased. Here we present findings from a minor nesting site in the Mediterranean, where the hatchling sex ratio was found to be male-biased, suggesting a potential difference between major and minor nesting sites. PMID:25379528

  16. The origin of female-biased sex ratios in intertidal seagrasses (Phyllospadix spp.).

    PubMed

    Shelton, Andrew Olaf

    2010-05-01

    Flowering sex ratios of dioecious plants are commonly male-biased but rarely female-biased. While greater costs of reproduction from females have been repeatedly demonstrated and explain male biases, male reproductive costs almost never exceed female costs, making the origins of female biases enigmatic. I investigated the seagrasses Phyllospadix scouleri and P. serrulatus (surfgrasses), which have some of the most extreme female-biased sex ratios documented (>90% female), to identify the mechanisms driving sex ratio bias. I developed sex-linked amplified fragment length polymorphism (AFLP) markers and applied them to three P. scouleri life stages at four sites to determine when during the life cycle sex ratio bias arises. Sex ratios were even among seedlings but became more female-biased at later life stages, indicating that sex ratios were driven by male-biased mortality. To identify when during the life cycle sex ratio bias developed, I examined sex differences in survival among seedlings and three aspects of reproductive costs that could potentially generate biased sex ratios under field conditions. No differences in seedling survival between the sexes were detected, and there was no evidence of substantial sex differences in costs of reproduction. I found no support for a trade-off between current and future reproduction or between reproductive investment and growth. Thus, costs of reproduction appear unlikely to drive sex ratio bias in surfgrass. Instead, small sex differences in growth and survival spread across the life cycle appear to be responsible for female-biased sex ratios and suggest that life history trade-offs other than reproductive costs drive sex ratio bias. PMID:20503870

  17. Sex Education for Deaf-Blind Youths and Adults.

    ERIC Educational Resources Information Center

    Ingraham, Cynthia L.; Vernon, McCay; Clemente, Brenda; Olney, Linda

    2000-01-01

    This article describes a model sex education program developed for youths and adults who are deafblind by the Helen Keller National Center for Deaf-Blind Youths and Adults. In addition, it also discusses major related issues and presents general recommendations and a resource for further information. (Contains 11 references.) (Author/CR)

  18. Relationship Formation and Stability in Emerging Adulthood: Do Sex Ratios Matter?

    ERIC Educational Resources Information Center

    Warner, Tara D.; Manning, Wendy D.; Giordano, Peggy C.; Longmore, Monica A.

    2011-01-01

    Research links sex ratios with the likelihood of marriage and divorce. However, whether sex ratios similarly influence precursors to marriage (transitions in and out of dating or cohabiting relationships) is unknown. Utilizing data from the Toledo Adolescent Relationships Study and the 2000 U.S. Census, this study assesses whether sex ratios…

  19. A heritable component in sex ratio and caste determination in a Cardiocondyla ant.

    PubMed

    Frohschammer, Sabine; Heinze, Jürgen

    2009-01-01

    Studies on sex ratios in social insects provide among the most compelling evidence for the importance of kin selection in social evolution. The elegant synthesis of Fisher's sex ratio principle and Hamilton's inclusive fitness theory predicts that colony-level sex ratios vary with the colonies' social and genetic structures. Numerous empirical studies in ants, bees, and wasps have corroborated these predictions. However, the evolutionary optimization of sex ratios requires genetic variation, but one fundamental determinant of sex ratios - the propensity of female larvae to develop into young queens or workers ("queen bias") - is thought to be largely controlled by the environment. Evidence for a genetic influence on sex ratio and queen bias is as yet restricted to a few taxa, in particular hybrids.Because of the very short lifetime of their queens, ants of the genus Cardiocondyla are ideal model systems for the study of complete lifetime reproductive success, queen bias, and sex ratios. We found that lifetime sex ratios of the ant Cardiocondyla kagutsuchi have a heritable component. In experimental single-queen colonies, 22 queens from a genetic lineage with a highly female-biased sex ratio produced significantly more female-biased offspring sex ratios than 16 queens from a lineage with a more male-biased sex ratio (median 91.5% vs. 58.5% female sexuals). Sex ratio variation resulted from different likelihood of female larvae developing into sexuals (median 50% vs. 22.6% female sexuals) even when uniformly nursed by workers from another colony.Consistent differences in lifetime sex ratios and queen bias among queens of C. kagutsuchi suggest that heritable, genetic or maternal effects strongly affect caste determination. Such variation might provide the basis for adaptive evolution of queen and worker strategies, though it momentarily constrains the power of workers and queens to optimize caste ratios. PMID:19863794

  20. Male-biased sex ratio does not promote increased sperm competitiveness in the seed beetle, Callosobruchus maculatus

    PubMed Central

    McNamara, Kathryn B.; Robinson, Stephen P.; Rosa, Márta E.; Sloan, Nadia S.; van Lieshout, Emile; Simmons, Leigh W.

    2016-01-01

    Sperm competition risk and intensity can select for adaptations that increase male fertilisation success. Evolutionary responses are examined typically by generating increased strength of sexual selection via direct manipulation of female mating rates (by enforcing monandry or polyandry) or by alteration of adult sex ratios. Despite being a model species for sexual selection research, the effect of sexual selection intensity via adult sex-ratio manipulation on male investment strategies has not been investigated in the seed beetle, Callosobruchus maculatus. We imposed 32 generations of experimental evolution on 10 populations of beetles by manipulating adult sex ratio. Contrary to predictions, males evolving in male-biased populations did not increase their testes and accessory gland size. This absence of divergence in ejaculate investment was also reflected in the fact that males from male-biased populations were not more successful in either preventing females from remating, or in competing directly for fertilisations. These populations already demonstrate divergence in mating behaviour and immunity, suggesting sufficient generations have passed to allow divergence in physiological and behavioural traits. We propose several explanations for the absence of divergence in sperm competitiveness among our populations and the pitfalls of using sex ratio manipulation to assess evolutionary responses to sexual selection intensity. PMID:27306351

  1. Male-biased sex ratio does not promote increased sperm competitiveness in the seed beetle, Callosobruchus maculatus.

    PubMed

    McNamara, Kathryn B; Robinson, Stephen P; Rosa, Márta E; Sloan, Nadia S; van Lieshout, Emile; Simmons, Leigh W

    2016-01-01

    Sperm competition risk and intensity can select for adaptations that increase male fertilisation success. Evolutionary responses are examined typically by generating increased strength of sexual selection via direct manipulation of female mating rates (by enforcing monandry or polyandry) or by alteration of adult sex ratios. Despite being a model species for sexual selection research, the effect of sexual selection intensity via adult sex-ratio manipulation on male investment strategies has not been investigated in the seed beetle, Callosobruchus maculatus. We imposed 32 generations of experimental evolution on 10 populations of beetles by manipulating adult sex ratio. Contrary to predictions, males evolving in male-biased populations did not increase their testes and accessory gland size. This absence of divergence in ejaculate investment was also reflected in the fact that males from male-biased populations were not more successful in either preventing females from remating, or in competing directly for fertilisations. These populations already demonstrate divergence in mating behaviour and immunity, suggesting sufficient generations have passed to allow divergence in physiological and behavioural traits. We propose several explanations for the absence of divergence in sperm competitiveness among our populations and the pitfalls of using sex ratio manipulation to assess evolutionary responses to sexual selection intensity. PMID:27306351

  2. Arachidonic acid enhances reproduction in Daphnia magna and mitigates changes in sex ratios induced by pyriproxyfen.

    PubMed

    Ginjupalli, Gautam K; Gerard, Patrick D; Baldwin, William S

    2015-03-01

    Arachidonic acid is 1 of only 2 unsaturated fatty acids retained in the ovaries of crustaceans and an inhibitor of HR97g, a nuclear receptor expressed in adult ovaries. The authors hypothesized that, as a key fatty acid, arachidonic acid may be associated with reproduction and potentially environmental sex determination in Daphnia. Reproduction assays with arachidonic acid indicate that it alters female:male sex ratios by increasing female production. This reproductive effect only occurred during a restricted Pseudokirchneriella subcapitata diet. Next, the authors tested whether enriching a poorer algal diet (Chlorella vulgaris) with arachidonic acid enhances overall reproduction and sex ratios. Arachidonic acid enrichment of a C. vulgaris diet also enhances fecundity at 1.0 µM and 4.0 µM by 30% to 40% in the presence and absence of pyriproxyfen. This indicates that arachidonic acid is crucial in reproduction regardless of environmental sex determination. Furthermore, the data indicate that P. subcapitata may provide a threshold concentration of arachidonic acid needed for reproduction. Diet-switch experiments from P. subcapitata to C. vulgaris mitigate some, but not all, of arachidonic acid's effects when compared with a C. vulgaris-only diet, suggesting that some arachidonic acid provided by P. subcapitata is retained. In summary, arachidonic acid supplementation increases reproduction and represses pyriproxyfen-induced environmental sex determination in D. magna in restricted diets. A diet rich in arachidonic acid may provide protection from some reproductive toxicants such as the juvenile hormone agonist pyriproxyfen. Environ Toxicol Chem 2015;34:527-535. © 2014 SETAC. PMID:25393616

  3. [Offspring Sex Ratio in the Captive Population of Siberian Crane (Grus leucogeranus Pallas)].

    PubMed

    Mudrik, E A; Kashentseva, T A; Postelnykh, K A; Nosachenko, G V; Politov, D V

    2015-12-01

    The sex ratio of Siberian crane chicks (Grus leucogeranus Pallas) from the captive population ofthe Oka Crane Breeding Center was analyzed with the use of molecular sex marker EE0.6 in 2009-2014. We determined the sex of 84 birds bred from 12 dams by means of artificial insemination and natural breeding. The total primary sex ratio was 40:44, and the secondary sex ratio was 36:39 with a minor predominance of females. The mortality rate of embryos was the same for both sexes. The primary and secondary sex ratio among the first eggs in clutches showed the same trends as those observed in general analysis. The relatedness of parents by microsatellite DNA has no effect on offspring sex in both natural breeding and artificial insemination. PMID:27055304

  4. Sex ratios of births, mortality, and air pollution: can measuring the sex ratios of births help to identify health hazards from air pollution in industrial environments?

    PubMed Central

    Williams, F L; Ogston, S A; Lloyd, O L

    1995-01-01

    OBJECTIVES--To compare the sex ratios of births and mortality in 12 Scottish localities with residential exposure to pollution from a variety of industrial sources with those in 12 nearby and comparable localities without such exposure. METHODS--24 localities were defined by postcode sectors. SMRs for lung cancer and for all causes of death and sex ratios of births were calculated for each locality for the years 1979-83. Log linear regression was used to assess the relation between exposure, sex ratios, and mortality. RESULTS--Mortalities from all causes were consistently and significantly higher in the residential areas exposed to air pollution than in the non-exposed areas. A similar, but less consistently significant, excess of mortality from lung cancer in the exposed areas was also found. The associations between exposure to the general air pollution and abnormal sex ratios, and between abnormal sex ratios and mortality, were negligible. CONCLUSIONS--Sex ratios were not consistently affected when the concentrations or components of the air pollution were insufficiently toxic to cause substantially increased death rates. Monitoring of the sex ratio does not provide a reliable screening measure for detecting cryptic health hazards from industrial air pollution in the general residential environment. PMID:7735388

  5. Birth Order and Sibling Sex Ratio of Children and Adolescents Referred to a Gender Identity Service

    PubMed Central

    VanderLaan, Doug P.; Blanchard, Ray; Wood, Hayley; Zucker, Kenneth J.

    2014-01-01

    In adult male samples, homosexuality is associated with a preponderance of older brothers (i.e., the fraternal birth order effect). In several studies comparing gender dysphoric youth, who are likely to be homosexual in adulthood, to clinical or non-clinical control groups, the findings have been consistent with the fraternal birth order effect in males; however, less is known about unique sibship characteristics of gender dysphoric females. The current study investigated birth order and sibling sex ratio in a large sample of children and adolescents referred to the same Gender Identity Service (N = 768). Probands were classified as heterosexual males, homosexual males, or homosexual females based on clinical diagnostic information. Groups differed significantly in age and sibship size, and homosexual females were significantly more likely to be only children. Subsequent analyses controlled for age and for sibship size. Compared to heterosexual males, homosexual males had a significant preponderance of older brothers and homosexual females had a significant preponderance of older sisters. Similarly, the older sibling sex ratio of homosexual males showed a significant excess of brothers whereas that of homosexual females showed a significant excess of sisters. Like previous studies of gender dysphoric youth and adults, these findings were consistent with the fraternal birth order effect. In addition, the greater frequency of only children and elevated numbers of older sisters among the homosexual female group adds to a small literature on sibship characteristics of potential relevance to the development of gender identity and sexual orientation in females. PMID:24651045

  6. Birth order and sibling sex ratio of children and adolescents referred to a gender identity service.

    PubMed

    Vanderlaan, Doug P; Blanchard, Ray; Wood, Hayley; Zucker, Kenneth J

    2014-01-01

    In adult male samples, homosexuality is associated with a preponderance of older brothers (i.e., the fraternal birth order effect). In several studies comparing gender dysphoric youth, who are likely to be homosexual in adulthood, to clinical or non-clinical control groups, the findings have been consistent with the fraternal birth order effect in males; however, less is known about unique sibship characteristics of gender dysphoric females. The current study investigated birth order and sibling sex ratio in a large sample of children and adolescents referred to the same Gender Identity Service (N = 768). Probands were classified as heterosexual males, homosexual males, or homosexual females based on clinical diagnostic information. Groups differed significantly in age and sibship size, and homosexual females were significantly more likely to be only children. Subsequent analyses controlled for age and for sibship size. Compared to heterosexual males, homosexual males had a significant preponderance of older brothers and homosexual females had a significant preponderance of older sisters. Similarly, the older sibling sex ratio of homosexual males showed a significant excess of brothers whereas that of homosexual females showed a significant excess of sisters. Like previous studies of gender dysphoric youth and adults, these findings were consistent with the fraternal birth order effect. In addition, the greater frequency of only children and elevated numbers of older sisters among the homosexual female group adds to a small literature on sibship characteristics of potential relevance to the development of gender identity and sexual orientation in females. PMID:24651045

  7. Proximate causes of the variation of the human sex ratio at birth.

    PubMed

    James, William H

    2015-12-01

    There is evidence that the human sex ratio (proportion males at birth) is the result of two processes. First, the sexes of zygotes (from which the primary sex ratio would be calculated) are thought to be partially controlled by the hormone levels of both parents around the time of conception. Second, this primary sex ratio is apparently modified downwards by male-sex-selective spontaneous abortion caused by high levels of maternal stress-induced adrenal androgens, thus yielding the sex ratio at birth (the secondary sex ratio). Since maternal stress is one cause of spontaneous abortion (and of other forms of reproductive sub-optimality), and since some forms of pharmacological treatment of maternal stress are deleterious to the foetus, best practice would suggest non-pharmacological treatment (e.g. psychotherapy, hypnosis or massage) for pregnant women who have a previous history of spontaneous abortion, preterm birth or low-birth-weight infants. PMID:26549774

  8. Recognition and Sex Categorization of Adults' and Children's Faces: Examining Performance in the Absence of Sex-Stereotyped Cues.

    ERIC Educational Resources Information Center

    Wild, Heather A.; Barett, Susan E.; Spence, Melanie J.; O'Toole, Alice J.; Cheng, Yi D.; Brooke, Jessica

    2000-01-01

    Investigated 7-year-olds', 9-year-olds', and adults' ability to classify children's and adults' faces by sex using only biological based internal facial structure. Found that participants categorized adult faces by sex at accuracy levels varying from just above chance (7-year-olds) to nearly perfect (adults). All groups were less accurate for…

  9. Sex ratio and spatial distribution of male and female Antennaria dioica (Asteraceae) plants

    NASA Astrophysics Data System (ADS)

    Varga, Sandra; Kytöviita, Minna-Maarit

    2011-09-01

    Sex ratio, sex spatial distribution and sexual dimorphism in reproduction and arbuscular mycorrhizal colonisation were investigated in the dioecious clonal plant Antennaria dioica (Asteraceae). Plants were monitored for five consecutive years in six study plots in Oulanka, northern Finland. Sex ratio, spatial distribution of sexes, flowering frequency, number of floral shoots and the number and weight of inflorescences were recorded. In addition, intensity of mycorrhizal fungi in the roots was assessed. Both sexes flowered each year with a similar frequency, but the overall genet sex ratio was strongly female-biased. The bivariate Ripley's analysis of the sex distribution showed that within most plots sexes were randomly distributed except for one plot. Sexual dimorphism was expressed as larger floral and inflorescence production and heavier inflorescences in males. In addition, the roots of both sexes were colonised to a similar extent by arbuscular mycorrhizal fungi. The female sex-biased flowering ratios reported are not consistent among years and cannot be explained in terms of spatial segregation of the sexes or sex lability. The possible reasons for the female-biased sex ratio are discussed.

  10. Maternal Condition but Not Corticosterone Is Linked to Offspring Sex Ratio in a Passerine Bird

    PubMed Central

    Henderson, Lindsay J.; Evans, Neil P.; Heidinger, Britt J.; Adams, Aileen; Arnold, Kathryn E.

    2014-01-01

    There is evidence of offspring sex ratio adjustment in a range of species, but the potential mechanisms remain largely unknown. Elevated maternal corticosterone (CORT) is associated with factors that can favour brood sex ratio adjustment, such as reduced maternal condition, food availability and partner attractiveness. Therefore, the steroid hormone has been suggested to play a key role in sex ratio manipulation. However, despite correlative and causal evidence CORT is linked to sex ratio manipulation in some avian species, the timing of adjustment varies between studies. Consequently, whether CORT is consistently involved in sex-ratio adjustment, and how the hormone acts as a mechanism for this adjustment remains unclear. Here we measured maternal baseline CORT and body condition in free-living blue tits (Cyanistes caeruleus) over three years and related these factors to brood sex ratio and nestling quality. In addition, a non-invasive technique was employed to experimentally elevate maternal CORT during egg laying, and its effects upon sex ratio and nestling quality were measured. We found that maternal CORT was not correlated with brood sex ratio, but mothers with elevated CORT fledged lighter offspring. Also, experimental elevation of maternal CORT did not influence brood sex ratio or nestling quality. In one year, mothers in superior body condition produced male biased broods, and maternal condition was positively correlated with both nestling mass and growth rate in all years. Unlike previous studies maternal condition was not correlated with maternal CORT. This study provides evidence that maternal condition is linked to brood sex ratio manipulation in blue tits. However, maternal baseline CORT may not be the mechanistic link between the maternal condition and sex ratio adjustment. Overall, this study serves to highlight the complexity of sex ratio adjustment in birds and the difficulties associated with identifying sex biasing mechanisms. PMID:25347532

  11. Sex Determination in Bluegill Sunfish Lepomis macrochirus: Effect of Temperature on Sex Ratio of Four Geographic Strains.

    PubMed

    Shen, Zhi-Gang; Wang, Han-Ping; Yao, Hong; O'Bryant, Paul; Rapp, Dean; Zhu, Kun-Qian

    2016-06-01

    There is increasing evidence that temperature effects on sex ratio in fish species are ubiquitous. Temperature effects on sex ratio could be influenced by parent, strain, and population, whether in fish species with temperature-dependent sex determination or genetic sex determination plus temperature effects. In the present study, effects of genotype-temperature interactions on sex determination in bluegill sunfish were further investigated, based on our previous results, using four geographic strains: Hebron, Jones, Hocking, and Missouri. In the Hebron strain, the two higher-temperature treatment groups (24 °C and 32 °C) produced more males than the low-temperature treatment group (17 °C) from 6 days post-hatching (dph) to 90 dph. In contrast, the low-temperature treatment produced more males than the other two higher-temperature treatments in the Jones strain. No significant effects of temperature on sex ratio were detected in the other two strains. Our results from sex ratio variance in different treatment times suggest that the thermosensitive period of sex differentiation occurs prior to 40 dph. Our results further confirmed that genotype-temperature interactions influence sex determination in bluegill. Therefore, to significantly increase the proportion of males, which grow faster and larger than females, a consumer- and environment-friendly approach may be achieved through selection of temperature sensitivity in bluegill. PMID:27365415

  12. Spiteful soldiers and sex ratio conflict in polyembryonic parasitoid wasps.

    PubMed

    Gardner, Andy; Hardy, Ian C W; Taylor, Peter D; West, Stuart A

    2007-04-01

    The existence of spiteful behaviors remains controversial. Spiteful behaviors are those that are harmful to both the actor and the recipient, and they represent one of the four fundamental types of social behavior (alongside selfishness, altruism, and mutual benefit). It has generally been assumed that the conditions required for spite to evolve are too restrictive, and so spite is unlikely to be important. This idea has been challenged in recent years, with the realization that localized competition can relax the conditions required for spite to evolve. Here we develop a theoretical model for a prime candidate for a spiteful behavior, the production of the sterile soldier caste in polyembryonic wasps. Our results show that (a) the biology of these soldiers is consistent with their main role being to mediate conflict over the sex ratio and not to defend against competitors and (b) greater conflict will occur in more outbred populations. We also show that the production of the sterile soldier caste can be classed as a spiteful behavior but that, to an extent, this is merely a semantic choice, and other interpretations such as altruism or indirect altruism are valid. However, the spite interpretation is useful in that it can lead to a more natural interpretation of relatedness and facilitate the classification of behaviors in a way that emphasizes biologically interesting differences that can be empirically tested. PMID:17427122

  13. Adaptive sex ratio variation in pre-industrial human (Homo sapiens) populations?

    PubMed Central

    Lummaa, V; Merilä, J; Kause, A

    1998-01-01

    Sex allocation theory predicts that in a population with a biased operational sex ratio (OSR), parents will increase their fitness by adjusting the sex ratio of their progeny towards the rarer sex, until OSR has reached a level where the overproduction of either sex no longer increases a parent's probability of having grandchildren. Furthermore, in a monogamous mating system, a biased OSR is expected to lead to lowered mean fecundity among individuals of the more abundant sex. We studied the influence of OSR on the sex ratio of newborns and on the population birth rate using an extensive data set (n = 14,420 births) from pre-industrial (1775-1850) Finland. The overall effect of current OSR on sex ratio at birth was significant, and in the majority of the 21 parishes included in this study, more sons were produced when males were rarer than females. This suggests that humans adjusted the sex ratio of their offspring in response to the local OSR to maximize the reproductive success of their progeny. Birth rate and, presumably, also population growth rate increased when the sex ratio (males:females) among reproductive age classes approached equality. However, the strength of these patterns varied across the parishes, suggesting that factors other than OSR (e.g. socioeconomic or environmental factors may also have influenced the sex ratio at birth and the birth rate. PMID:9881467

  14. Oviposition and Sex Ratio of the Redbanded Stink Bug, Piezodorous guildinii, in Soybean.

    PubMed

    Temple, Joshua H; Davis, Jeffrey A; Hardke, Jarrod T; Price, Paul P; Leonard, B Rogers

    2016-01-01

    Redbanded stink bug, Piezodorus guildinii (Westwood), is a significant soybean pest across the mid-south region of the United States. The objectives of these studies were to characterize: (1) redbanded stink bug oviposition in relationship to soybean maturity group (MG), plant structure, crop phenology, and vertical distribution within the plant canopy; and (2) redbanded stink bug adult sex ratios in relationship to soybean phenology. A total of 5645 redbanded stink bug eggs in 421 egg masses (clusters) were field collected from naturally-occurring populations in MG IV and V soybean over a three year period (2009 to 2011). The mean number of eggs within a cluster was 16.6 ± 0.3. Plant structures by MG interactions were highly significant with more egg masses oviposited on leaves in MG IV (79.4%) and more on pods in MG V (72.7%). The ratio of females to males was similar in all soybean growth stages except R5, where the sex ratio increased to 1.4:1, coinciding with peak oviposition. Only 29.9% of egg clusters in MG IV and 18.3% of egg clusters in MG V were oviposited in the upper 35 cm of the soybean canopy. Based on these results, sampling strategies and insecticide application placement for stink bugs may require modification. PMID:27322333

  15. Oviposition and Sex Ratio of the Redbanded Stink Bug, Piezodorous guildinii, in Soybean

    PubMed Central

    Temple, Joshua H.; Davis, Jeffrey A.; Hardke, Jarrod T.; Price, Paul P.; Leonard, B. Rogers

    2016-01-01

    Redbanded stink bug, Piezodorus guildinii (Westwood), is a significant soybean pest across the mid-south region of the United States. The objectives of these studies were to characterize: (1) redbanded stink bug oviposition in relationship to soybean maturity group (MG), plant structure, crop phenology, and vertical distribution within the plant canopy; and (2) redbanded stink bug adult sex ratios in relationship to soybean phenology. A total of 5645 redbanded stink bug eggs in 421 egg masses (clusters) were field collected from naturally-occurring populations in MG IV and V soybean over a three year period (2009 to 2011). The mean number of eggs within a cluster was 16.6 ± 0.3. Plant structures by MG interactions were highly significant with more egg masses oviposited on leaves in MG IV (79.4%) and more on pods in MG V (72.7%). The ratio of females to males was similar in all soybean growth stages except R5, where the sex ratio increased to 1.4:1, coinciding with peak oviposition. Only 29.9% of egg clusters in MG IV and 18.3% of egg clusters in MG V were oviposited in the upper 35 cm of the soybean canopy. Based on these results, sampling strategies and insecticide application placement for stink bugs may require modification. PMID:27322333

  16. Ecological context and metapopulation dynamics affect sex-ratio variation among dioecious plant populations

    PubMed Central

    Field, David L.; Pickup, Melinda; Barrett, Spencer C. H.

    2013-01-01

    Background and Aims Populations of dioecious flowering plants commonly exhibit heterogeneity in sex ratios and deviations from the equilibrium expectation of equal numbers of females and males. Yet the role of ecological and demographic factors in contributing towards biased sex ratios is currently not well understood. Methods Species-level studies from the literature were analysed to investigate ecological correlates of among-population sex-ratio variation and metapopulation models and empirical data were used to explore the influence of demography and non-equilibrium conditions on flowering sex ratios. Key Results The survey revealed significant among-population heterogeneity in sex ratios and this was related to the degree of sampling effort. For some species, sex-ratio bias was associated with the proportion of non-reproductive individuals, with greater male bias in populations with a lower proportion of individuals that were flowering. Male-biased ratios were also found at higher altitudes and latitudes, and in more xeric sites. Simulations and empirical data indicated that clonal species exhibited greater heterogeneity in sex ratios than non-clonal species as a result of their slower approach to equilibrium. The simulations also indicated the importance of interactions between reproductive mode and founder effects, with greater departures from equilibrium in clonal populations with fewer founding individuals. Conclusions The results indicate that sex-based differences in costs of reproduction and non-equilibrium conditions can each play important roles in affecting flowering sex ratios in populations of dioecious plants. PMID:23444124

  17. Forest clearing and sex ratio in forest-dwelling wood ant Formica aquilonia

    NASA Astrophysics Data System (ADS)

    Sorvari, Jouni; Hakkarainen, Harri

    2007-05-01

    Sex ratios of ants have been shown to vary with food resource levels in several studies, but it is not known whether forest clear-cutting has any effect on sex ratio of aphid-tending forest-dwelling ants. We investigated whether the offspring sex ratio of the forest dwelling ant Formica aquilonia varied as a response to clear-cutting. We found that the proportion of males was smaller in clear-cuts than in adjacent forests. Our results are among the first showing that anthropogenic changes in forest structures may have a potential to modify sex ratios of social insects and other forest-dwelling animals.

  18. Invasion, Coexistence, and Extinction Driven by Preemptive Competition and Sex Ratio

    NASA Astrophysics Data System (ADS)

    Molnar, Ferenc; Caraco, Thomas; Korniss, Gyorgy

    2012-02-01

    We investigate competitive invasion in a simple population dynamics model, where females can differ genetically in the sex ratio of their offspring, and males can differ in mortality. Analyzing of the mean-field dynamics, we obtain conditions for ecological stability of a given sex-ratio allele for any mortality rate parameters. We also found that stable coexistence of the two alleles is possible, but only males can differ; one female phenotype is present. Our results show that the success of invasion is determined by the female birth sex ratio. A lower female ratio never excludes a larger female sex ratio; in case of coexistence, the surviving female phenotype always has the greater female sex ratio. Finally, we identified an interesting invasion-to-extinction scenario: successful invasion followed by extinction occurs when the invader initially propagates with the resident allele, but after excluding the resident, cannot survive on its own.

  19. Territory Quality and Plumage Morph Predict Offspring Sex Ratio Variation in a Raptor

    PubMed Central

    Chakarov, Nayden; Pauli, Martina; Mueller, Anna-Katharina; Potiek, Astrid; Grünkorn, Thomas; Dijkstra, Cor; Krüger, Oliver

    2015-01-01

    Parents may adapt their offspring sex ratio in response to their own phenotype and environmental conditions. The most significant causes for adaptive sex-ratio variation might express themselves as different distributions of fitness components between sexes along a given variable. Several causes for differential sex allocation in raptors with reversed sexual size dimorphism have been suggested. We search for correlates of fledgling sex in an extensive dataset on common buzzards Buteo buteo, a long-lived bird of prey. Larger female offspring could be more resource-demanding and starvation-prone and thus the costly sex. Prominent factors such as brood size and laying date did not predict nestling sex. Nonetheless, lifetime sex ratio (LSR, potentially indicative of individual sex allocation constraints) and overall nestling sex were explained by territory quality with more females being produced in better territories. Additionally, parental plumage morphs and the interaction of morph and prey abundance tended to explain LSR and nestling sex, indicating local adaptation of sex allocation However, in a limited census of nestling mortality, not females but males tended to die more frequently in prey-rich years. Also, although females could have potentially longer reproductive careers, a subset of our data encompassing full individual life histories showed that longevity and lifetime reproductive success were similarly distributed between the sexes. Thus, a basis for adaptive sex allocation in this population remains elusive. Overall, in common buzzards most major determinants of reproductive success appeared to have no effect on sex ratio but sex allocation may be adapted to local conditions in morph-specific patterns. PMID:26445010

  20. Sex Differences in the Manifestation of ADHD in Emerging Adults

    ERIC Educational Resources Information Center

    Fedele, David A.; Lefler, Elizabeth K.; Hartung, Cynthia M.; Canu, Will H.

    2012-01-01

    Objective: Given the mixed literature in the area, the aim of the current study was to determine whether sex differences exist in inattention, hyperactivity, and impairment in college adults with ADHD. Method: Individuals from three universities were recruited for the study. Participants with (n = 164) and without ADHD (n = 710) completed on-line…

  1. Student Sex: More or Less Risky than Other Young Adults?

    ERIC Educational Resources Information Center

    Burke, Lorraine; Nic Gabhainn, Saoirse; Young, Honor

    2015-01-01

    Sexually active young adults are at an increased risk of acquiring sexually transmitted infections (STIs) or experiencing an unplanned pregnancy. Sexual behaviours such as inconsistent condom use, multiple partners and casual sex are known risk factors for negative sexual health outcomes. Sexually active higher education students are classified as…

  2. Sex Ratio Adaptations to Local Mate Competition in a Parasitic Wasp.

    ERIC Educational Resources Information Center

    Werren, John H.

    1980-01-01

    This study discusses the behavior of the females of the parasitic wasp Nasonia vitripennis, which adjust the sex ratio of their broods according to whether or not they are the first or second wasp to parasitize a host. The results provide a quantitative test of sex ratio theory. (Author/SA)

  3. Sibling Sex Ratio of Individuals Diagnosed with Autism Spectrum Disorder as Children

    ERIC Educational Resources Information Center

    Mouridsen, Svend Erik; Rich, Bente; Isager, Torben

    2010-01-01

    Aim: To study the sex ratio (proportion of males) in siblings of individuals diagnosed with autism spectrum disorders (ASDs) as children. Method: In the current study, we extended previous studies dealing with the androgen theory of autism and examined sex ratios in the siblings of 326 individuals with ASD (245 males, 81 females) who had been…

  4. The financial consequences of too many men: sex ratio effects on saving, borrowing, and spending.

    PubMed

    Griskevicius, Vladas; Tybur, Joshua M; Ackerman, Joshua M; Delton, Andrew W; Robertson, Theresa E; White, Andrew E

    2012-01-01

    The ratio of males to females in a population is an important factor in determining behavior in animals. We propose that sex ratio also has pervasive effects in humans, such as by influencing economic decisions. Using both historical data and experiments, we examined how sex ratio influences saving, borrowing, and spending in the United States. Findings show that male-biased sex ratios (an abundance of men) lead men to discount the future and desire immediate rewards. Male-biased sex ratios decreased men's desire to save for the future and increased their willingness to incur debt for immediate expenditures. Sex ratio appears to influence behavior by increasing the intensity of same-sex competition for mates. Accordingly, a scarcity of women led people to expect men to spend more money during courtship, such as by paying more for engagement rings. These findings demonstrate experimentally that sex ratio influences human decision making in ways consistent with evolutionary biological theory. Implications for sex ratio effects across cultures are discussed. PMID:21767031

  5. The Financial Consequences of Too Many Men: Sex Ratio Effects on Saving, Borrowing, and Spending

    PubMed Central

    Griskevicius, Vladas; Tybur, Joshua M.; Ackerman, Joshua M.; Delton, Andrew W.; Robertson, Theresa E.; White, Andrew E.

    2012-01-01

    The ratio of males to females in a population is an important factor in determining behavior in animals. We propose that sex ratio also has pervasive effects in humans, such as by influencing economic decisions. Using both historical data and experiments, we examined how sex ratio influences saving, borrowing, and spending in the United States. Findings show that male-biased sex ratios (an abundance of men) lead men to discount the future and desire immediate rewards. Male-biased sex ratios decreased men’s desire to save for the future and increased their willingness to incur debt for immediate expenditures. Sex ratio appears to influence behavior by increasing the intensity of same-sex competition for mates. Accordingly, a scarcity of women led people to expect men to spend more money during courtship, such as by paying more for engagement rings. These findings demonstrate experimentally that sex ratio influences human decision making in ways consistent with evolutionary biological theory. Implications for sex ratio effects across cultures are discussed. PMID:21767031

  6. On the Relationship between Marital Opportunity and Teen Pregnancy: The Sex Ratio Question.

    ERIC Educational Resources Information Center

    Barber, Nigel

    2001-01-01

    Used United Nations cross-national data to examine the relationship between low sex ratio, marital opportunity, and teen pregnancy. Geographical region, per capita gross national product, marital rate, and urban and rural status were used as control variables in analyses that utilized sex ratios to predict teen births. Overall, early childbearing…

  7. INFLUENCE OF ENVIRONMENTAL TEMPERATURE ON SEX-RATIOS IN THE TIDEWATER SILVERSIDE, 'MENIDIA PENINSULAE' (PISCES: ATHERINIDAE)

    EPA Science Inventory

    The sex-ratios of Menidia peninsulae from Santa Rosa Island, Florida were studied during a 13 month survey. Weekly samples revealed significant deviations from the expected sex-ratio of 1:1. During May-October, young-of-the-year (YOY) females comprised 70 to 94% of the individual...

  8. The Maternal Legacy: Female Identity Predicts Offspring Sex Ratio in the Loggerhead Sea Turtle

    PubMed Central

    Reneker, Jaymie L.; Kamel, Stephanie J.

    2016-01-01

    In organisms with temperature-dependent sex determination, the incubation environment plays a key role in determining offspring sex ratios. Given that global temperatures have warmed approximately 0.6 °C in the last century, it is necessary to consider how organisms will adjust to climate change. To better understand the degree to which mothers influence the sex ratios of their offspring, we use 24 years of nesting data for individual female loggerhead sea turtles (Caretta caretta) observed on Bald Head Island, North Carolina. We find that maternal identity is the best predictor of nest sex ratio in univariate and multivariate predictive models. We find significant variability in estimated nest sex ratios among mothers, but a high degree of consistency within mothers, despite substantial spatial and temporal thermal variation. Our results suggest that individual differences in nesting preferences are the main driver behind divergences in nest sex ratios. As such, a female’s ability to plastically adjust her nest sex ratios in response to environmental conditions is constrained, potentially limiting how individuals behaviorally mitigate the effects of environmental change. Given that many loggerhead populations already show female-biased offspring sex ratios, understanding maternal behavioral responses is critical for predicting the future of long-lived species vulnerable to extinction. PMID:27363786

  9. Mother's prior intrauterine position affects the sex ratio of her offspring in house mice.

    PubMed Central

    Vandenbergh, J G; Huggett, C L

    1994-01-01

    Sex ratio alterations related to environmental factors occur in several mammals, but no mechanism has been identified to explain the adjustment. Intrauterine position (IUP) may provide the context in which such alterations occur. Previous studies on house mice and gerbils reveal that the position of a fetus in the uterus in relation to the sex of its neighbors influences its later anatomy, physiology, and behavior. The anogenital distance (AGD) of females located between two males (2M) is longer than that of females not between two males (OM). We have found that the IUP, as determined by cesarean section and by an index of the AGD, correlates with the sex ratio of the litters produced by female mice. The sex ratio of the first litter born to 2M females was 58% males, for 1M females was 51% males and for OM females was 42% males. The effect on sex ratio continues into the second litter. The number of pups produced by mothers of different IUPs in her first two litters did not differ, suggesting that the sex ratio adjustment occurs prior to parturition. These results provide a basis for the natural variability observed in sex ratios of litter-bearing mammals and suggest that one or more intrauterine mechanisms may be responsible for environmentally related sex ratio alterations. PMID:7972008

  10. The Maternal Legacy: Female Identity Predicts Offspring Sex Ratio in the Loggerhead Sea Turtle.

    PubMed

    Reneker, Jaymie L; Kamel, Stephanie J

    2016-01-01

    In organisms with temperature-dependent sex determination, the incubation environment plays a key role in determining offspring sex ratios. Given that global temperatures have warmed approximately 0.6 °C in the last century, it is necessary to consider how organisms will adjust to climate change. To better understand the degree to which mothers influence the sex ratios of their offspring, we use 24 years of nesting data for individual female loggerhead sea turtles (Caretta caretta) observed on Bald Head Island, North Carolina. We find that maternal identity is the best predictor of nest sex ratio in univariate and multivariate predictive models. We find significant variability in estimated nest sex ratios among mothers, but a high degree of consistency within mothers, despite substantial spatial and temporal thermal variation. Our results suggest that individual differences in nesting preferences are the main driver behind divergences in nest sex ratios. As such, a female's ability to plastically adjust her nest sex ratios in response to environmental conditions is constrained, potentially limiting how individuals behaviorally mitigate the effects of environmental change. Given that many loggerhead populations already show female-biased offspring sex ratios, understanding maternal behavioral responses is critical for predicting the future of long-lived species vulnerable to extinction. PMID:27363786

  11. Variably male-biased sex ratio in a marine bird with females larger than males.

    PubMed

    Torres, R; Drummond, H

    1999-01-01

    When the costs of rearing males and females differ progeny sex ratios are expected to be biased toward the less expensive sex. Blue-footed booby (Sula nebouxii) females are larger and roughly 32% heavier than males, thus presumably more costly to rear. We recorded hatching and fledging sex ratios in 1989, and fledging sex ratios during the next 5 years. In 1989, the sample of 751 chicks showed male bias at hatching (56%) and at fledging (57% at 90 days). Fledging sex ratios during the five subsequent reproductive seasons were at unity (1 year) or male-biased, varying from 56% to 70%. Male bias was greater during years when mean sea surface temperature was warmer and food was presumably in short supply. During two warm-water years (only) fledging sex ratio varied with hatching date. Proportions of male fledglings increased with date from 0.48 to 0.73 in 1994, and from 0.33 to 0.79 in 1995. Similar results were obtained when the analysis was repeated using only broods with no nestling mortality, suggesting that the overall increase in the proportion of males over the season was the result of sex ratio adjustments at hatching. The male-biased sex ratio, and the increased male bias during poor breeding conditions supports the idea that daughters may be more costly than sons, and that their relative cost increases in poor conditions. PMID:20135156

  12. Sexual Abuse History among Adult Sex Offenders and Non-Sex Offenders: A Meta-Analysis

    ERIC Educational Resources Information Center

    Jespersen, Ashley F.; Lalumiere, Martin L.; Seto, Michael C.

    2009-01-01

    Objective: The sexually abused-sexual abuser hypothesis states there is a specific relationship between sexual abuse history and sexual offending, such that individuals who experience sexual abuse are significantly more likely to later engage in sexual offenses. Therefore, samples of adult sex offenders should contain a disproportionate number of…

  13. Sexual system, sex ratio, and group living in the shrimp Thor amboinensis (De Man): relevance to resource-monopolization and sex-allocation theories.

    PubMed

    Baeza, J A; Piantoni, C

    2010-10-01

    The sexual system of the symbiotic shrimp Thor amboinensis is described, along with observations on sex ratio and host-use pattern of different populations. We used a comprehensive approach to elucidate the previously unknown sexual system of this shrimp. Dissections, scanning electron microscopy, size-frequency distribution analysis, and laboratory observations demonstrated that T. amboinensis is a protandric hermaphrodite: shrimp first mature as males and change into females later in life. Thor amboinensis inhabited the large and structurally heterogeneous sea anemone Stichodactyla helianthus in large groups (up to 11 individuals) more frequently than expected by chance alone. Groups exhibited no particularly complex social structure and showed male-biased sex ratios more frequently than expected by chance alone. The adult sex ratio was male-biased in the four separate populations studied, one of them being thousands of kilometers apart from the others. This study supports predictions central to theories of resource monopolization and sex allocation. Dissections demonstrated that unusually large males were parasitized by an undescribed species of isopod (family Entoniscidae). Infestation rates were similarly low in both sexes (≈11%-12%). The available information suggests that T. amboinensis uses pure search promiscuity as a mating system. This hypothesis needs to be formally tested with mating behavior observations and field measurements on the movement pattern of both sexes of the species. Further detailed studies on the lifestyle and sexual system of all the species within this genus and the development of a molecular phylogeny are necessary to elucidate the evolutionary history of gender expression in the genus Thor. PMID:20972260

  14. Secular trends in human sex ratios : Their influence on individual and family behavior.

    PubMed

    Pedersen, F A

    1991-09-01

    Secular change in sex ratios is examined in relation to experience in the family. Two theoretical perspectives are outlined: Guttentag and Secord's (1983) adaptation of social exchange theory, and sexual selection theory. Because of large-scale change in number of births and typical age differentials between men and women at marriage, low sex ratios at couple formation ages existed in the U.S. between 1965 and the early 1980s. The currently high sex ratios, however, will persist until the end of the century. High sex ratios appear to be associated with lower divorce rates, male commitment to careers that promise economic rewards, male willingness to engage in child care, higher fertility, and higher rates of sexual violence. Sexual selection theory calls attention to intrasexual competition in the numerically larger sex. PMID:24222281

  15. Mating system and sex ratios of a pollinating fig wasp with dispersing males.

    PubMed Central

    Greeff, Jaco M

    2002-01-01

    Recent studies have used sex ratios to quantify the mating systems of organisms, the argument behind it being that more female-biased sex ratios are an indication of higher local mate competition, which goes hand-in-hand with higher levels of inbreeding. Although qualitative tests of the effects of mating systems on sex ratios abound, there is a dearth of studies that quantify both the mating system and the sex ratio. I use a colour dimorphism with a simple Mendelian inheritance to quantify the mating system of an unusual fig-pollinating wasp in which males disperse to obtain matings on non-natal mating patches. In qualitative agreement with initial expectations, the sex ratios of single foundresses are found to be higher than those of regular species. However, by quantifying the mating system, it is shown that the initial expectation is incorrect and this species' sex ratio is a poor predictor of its mating system (it underestimates the frequency of sib-mating). The species has a very high variance in sex ratio suggesting that excess males can simply avoid local mate competition (and hence a lowered fitness to their mother) by dispersing to other patches. PMID:12495498

  16. Sex-specific responses to climate change in plants alter population sex ratio and performance.

    PubMed

    Petry, William K; Soule, Judith D; Iler, Amy M; Chicas-Mosier, Ana; Inouye, David W; Miller, Tom E X; Mooney, Kailen A

    2016-07-01

    Males and females are ecologically distinct in many species, but whether responses to climate change are sex-specific is unknown. We document sex-specific responses to climate change in the plant Valeriana edulis (valerian) over four decades and across its 1800-meter elevation range. Increased elevation was associated with increased water availability and female frequency, likely owing to sex-specific water use efficiency and survival. Recent aridification caused male frequency to move upslope at 175 meters per decade, a rate of trait shift outpacing reported species' range shifts by an order of magnitude. This increase in male frequency reduced pollen limitation and increased seedset. Coupled with previous studies reporting sex-specific arthropod communities, these results underscore the importance of ecological differences between the sexes in mediating biological responses to climate change. PMID:27365446

  17. Human sex ratio at birth and residential proximity to nuclear facilities in France.

    PubMed

    Scherb, Hagen; Kusmierz, Ralf; Voigt, Kristina

    2016-04-01

    The possible detrimental genetic impact on humans living in the vicinity of nuclear facilities has been previously studied. We found evidence for an increase in the human secondary sex ratio (sex odds) within distances of up to 35km from nuclear facilities in Germany and Switzerland. Here, we extend our pilot investigations using new comprehensive data from France. The French data (1968-2011) account for 36,565 municipalities with 16,968,701 male and 16,145,925 female births. The overall sex ratio was 1.0510. Using linear and nonlinear logistic regression models with dummy variables coding for appropriately grouped municipalities, operation time periods, and corresponding spatiotemporal interactions, we consider the association between annual municipality-level birth sex ratios and minimum distances of municipalities from nuclear facilities. Within 35km from 28 nuclear sites in France, the sex ratio is increased relative to the rest of France with a sex odds ratio (SOR) of 1.0028, (95% CI: 1.0007, 1.0049). The detected association between municipalities' minimum distances from nuclear facilities and the sex ratio in France corroborates our findings for Germany and Switzerland. PMID:26880420

  18. Queering Sex Education: Young Adult Literature with LGBT Content as Complementary Sources of Sex and Sexuality Education

    ERIC Educational Resources Information Center

    Bittner, Robert

    2012-01-01

    This article explores the nature of young adult texts as complementary sources of informal queer sex and sexuality education, along with a close reading of a sample of this young adult (YA) literature. LGBT teens are often left out of discussions in sex education classrooms in the United States because of discriminatory curricula, ignorance on the…

  19. Sex ratio at birth and mortality rates are negatively related in humans.

    PubMed

    Dama, Madhukar Shivajirao

    2011-01-01

    Evolutionary theory posits that resource availability and parental investment ability could signal offspring sex selection, in order to maximize reproductive returns. Non-human studies have provided evidence for this phenomenon, and maternal condition around the time of conception has been identified as most important factor that influence offspring sex selection. However, studies on humans have reported inconsistent results, mostly due to use of disparate measures as indicators of maternal condition. In the present study, the cross-cultural differences in human natal sex ratio were analyzed with respect to indirect measures of condition namely, life expectancy and mortality rate. Multiple regression modeling suggested that mortality rates have distinct predictive power independent of cross-cultural differences in fertility, wealth and latitude that were earlier shown to predict sex ratio at birth. These findings suggest that sex ratio variation in humans may relate to differences in parental and environmental conditions. PMID:21887320

  20. Sex Ratio at Birth and Mortality Rates Are Negatively Related in Humans

    PubMed Central

    Dama, Madhukar Shivajirao

    2011-01-01

    Evolutionary theory posits that resource availability and parental investment ability could signal offspring sex selection, in order to maximize reproductive returns. Non-human studies have provided evidence for this phenomenon, and maternal condition around the time of conception has been identified as most important factor that influence offspring sex selection. However, studies on humans have reported inconsistent results, mostly due to use of disparate measures as indicators of maternal condition. In the present study, the cross-cultural differences in human natal sex ratio were analyzed with respect to indirect measures of condition namely, life expectancy and mortality rate. Multiple regression modeling suggested that mortality rates have distinct predictive power independent of cross-cultural differences in fertility, wealth and latitude that were earlier shown to predict sex ratio at birth. These findings suggest that sex ratio variation in humans may relate to differences in parental and environmental conditions. PMID:21887320

  1. Persistent unequal sex ratio in a population of grayling (Salmonidae) and possible role of temperature increase.

    PubMed

    Wedekind, Claus; Evanno, Guillaume; Székely, Tamás; Pompini, Manuel; Darbellay, Olivier; Guthruf, Joachim

    2013-02-01

    In some fishes, water chemistry or temperature affects sex determination or creates sex-specific selection pressures. The resulting population sex ratios are hard to predict from laboratory studies if the environmental triggers interact with other factors, whereas in field studies, singular observations of unusual sex ratios may be particularly prone to selective reporting. Long-term monitoring largely avoids these problems. We studied a population of grayling (Thymallus thymallus) in Lake Thun, Switzerland, that has been monitored since 1948. Samples of spawning fish have been caught about 3 times/week around spawning season, and water temperature at the spawning site has been continuously recorded since 1970. We used scale samples collected in different years to determine the average age of spawners (for life-stage specific analyses) and to identify the cohort born in 2003 (an extraordinarily warm year). Recent tissue samples were genotyped on microsatellite markers to test for genetic bottlenecks in the past and to estimate the genetically effective population size (N(e)). Operational sex ratios changed from approximately 65% males before 1993 to approximately 85% males from 1993 to 2011. Sex ratios correlated with the water temperatures the fish experienced in their first year of life. Sex ratios were best explained by the average temperature juvenile fish experienced during their first summer. Grayling abundance is declining, but we found no evidence of a strong genetic bottleneck that would explain the apparent lack of evolutionary response to the unequal sex ratio. Results of other studies show no evidence of endocrine disruptors in the study area. Our findings suggest temperature affects population sex ratio and thereby contributes to population decline. PMID:22891785

  2. Under what conditions do climate-driven sex ratios enhance versus diminish population persistence?

    PubMed Central

    Boyle, Maria; Hone, Jim; Schwanz, Lisa E; Georges, Arthur

    2014-01-01

    For many species of reptile, crucial demographic parameters such as embryonic survival and individual sex (male or female) depend on ambient temperature during incubation. While much has been made of the role of climate on offspring sex ratios in species with temperature-dependent sex determination (TSD), the impact of variable sex ratio on populations is likely to depend on how limiting male numbers are to female fecundity in female-biased populations, and whether a climatic effect on embryonic survival overwhelms or interacts with sex ratio. To examine the sensitivity of populations to these interacting factors, we developed a generalized model to explore the effects of embryonic survival, hatchling sex ratio, and the interaction between these, on population size and persistence while varying the levels of male limitation. Populations with TSD reached a greater maximum number of females compared to populations with GSD, although this was often associated with a narrower range of persistence. When survival depended on temperature, TSD populations persisted over a greater range of temperatures than GSD populations. This benefit of TSD was greatly reduced by even modest male limitation, indicating very strong importance of this largely unmeasured biologic factor. Finally, when males were not limiting, a steep relationship between sex ratio and temperature favoured population persistence across a wider range of climates compared to the shallower relationships. The opposite was true when males were limiting – shallow relationships between sex ratio and temperature allowed greater persistence. The results highlight that, if we are to predict the response of populations with TSD to climate change, it is imperative to 1) accurately quantify the extent to which male abundance limits female fecundity, and 2) measure how sex ratios and peak survival coincide over climate. PMID:25512848

  3. Maternally derived carotenoid pigments affect offspring survival, sex ratio, and sexual attractiveness in a colorful songbird

    NASA Astrophysics Data System (ADS)

    McGraw, K. J.; Adkins-Regan, E.; Parker, R. S.

    2005-08-01

    In egg-laying animals, mothers can influence the development of their offspring via the suite of biochemicals they incorporate into the nourishing yolk (e.g. lipids, hormones). However, the long-lasting fitness consequences of this early nutritional environment have often proved elusive. Here, we show that the colorful carotenoid pigments that female zebra finches ( Taeniopygia guttata) deposit into egg yolks influence embryonic and nestling survival, the sex ratio of fledged offspring, and the eventual ornamental coloration displayed by their offspring as adults. Mothers experimentally supplemented with dietary carotenoids prior to egg-laying incorporated more carotenoids into eggs, which, due to the antioxidant activity of carotenoids, rendered their embryos less susceptible to free-radical attack during development. These eggs were subsequently more likely to hatch, fledge offspring, produce more sons than daughters, and produce sons who exhibited more brightly colored carotenoid-based beak pigmentation. Provisioned mothers also acquired more colorful beaks, which directly predicted levels of carotenoids found in eggs, thus indicating that these pigments may function not only as physiological ‘damage-protectants’ in adults and offspring but also as morphological signals of maternal reproductive capabilities.

  4. TOO MANY MEN? SEX RATIOS AND WOMEN’S PARTNERING BEHAVIOR IN CHINA

    PubMed Central

    Trent, Katherine; South, Scott J.

    2011-01-01

    The relative numbers of women and men are changing dramatically in China, but the consequences of these imbalanced sex ratios have received little attention. We merge data from the Chinese Health and Family Life Survey with community-level data from Chinese censuses to examine the relationship between cohort- and community-specific sex ratios and women’s partnering behavior. Consistent with demographic-opportunity theory and sociocultural theory, we find that high sex ratios (indicating more men relative to women) are associated with an increased likelihood that women marry before age 25. However, high sex ratios are also associated with an increased likelihood that women engage in premarital and extramarital sexual relationships and have had more than one sexual partner, findings consistent with demographic-opportunity theory but inconsistent with sociocultural theory. PMID:22199403

  5. Invisible Victims: Delayed Onset Depression among Adults with Same-Sex Parents

    PubMed Central

    Sullins, D. Paul

    2016-01-01

    The relationship of elevated depression risk recently discovered among adult persons raised by same-sex parents with possible precipitating conditions in childhood has not previously been acknowledged. This study tests whether such inattention is supportable. Logistic regression based risk ratios were estimated from longitudinal measures of mental health outcomes observed in three waves (at ages 15, 22, and 28) of the US National Survey of Adolescent to Adult Health (n = 15,701). At age 28, the adults raised by same-sex parents were at over twice the risk of depression (CES-D: risk ratio 2.6, 95% CI 1.4–4.6) as persons raised by man-woman parents. These findings should be interpreted with caution. Elevated risk was associated with imbalanced parental closeness and parental child abuse in family of origin; depression, suicidality, and anxiety at age 15; and stigma and obesity. More research and policy attention to potentially problematic conditions for children with same-sex parents appears warranted. PMID:27313882

  6. Invisible Victims: Delayed Onset Depression among Adults with Same-Sex Parents.

    PubMed

    Sullins, D Paul

    2016-01-01

    The relationship of elevated depression risk recently discovered among adult persons raised by same-sex parents with possible precipitating conditions in childhood has not previously been acknowledged. This study tests whether such inattention is supportable. Logistic regression based risk ratios were estimated from longitudinal measures of mental health outcomes observed in three waves (at ages 15, 22, and 28) of the US National Survey of Adolescent to Adult Health (n = 15,701). At age 28, the adults raised by same-sex parents were at over twice the risk of depression (CES-D: risk ratio 2.6, 95% CI 1.4-4.6) as persons raised by man-woman parents. These findings should be interpreted with caution. Elevated risk was associated with imbalanced parental closeness and parental child abuse in family of origin; depression, suicidality, and anxiety at age 15; and stigma and obesity. More research and policy attention to potentially problematic conditions for children with same-sex parents appears warranted. PMID:27313882

  7. The sex ratio distortion in the human head louse is conserved over time

    PubMed Central

    Perotti, M Alejandra; Catalá, Silvia S; Ormeño, Analía del V; Żelazowska, Monika; Biliński, Szczepan M; Braig, Henk R

    2004-01-01

    Background At the turn of the 19th century the first observations of a female-biased sex ratio in broods and populations of the head louse, Pediculus humanus capitis, had been reported. A study by Buxton in 1940 on the sex ratio of lice on prisoners in Ceylon is still today the subject of reanalyses. This sex ratio distortion had been detected in ten different countries. In the last sixty years no new data have been collected, especially on scalp infestations under economically and socially more developed conditions. Results Here we report a female bias of head lice in a survey of 480 school children in Argentina. This bias is independent of the intensity of the pediculosis, which makes local mate competition highly unlikely as the source of the aberrant sex ratio; however, other possible adaptive mechanisms cannot be discounted. These lice as well as lice from pupils in Britain were carrying several strains of the endosymbiotic bacterium Wolbachia pipientis, one of the most wide spread intracellular sex ratio distorters. Similar Wolbachia strains are also present in the pig louse, Haematopinus suis, suggesting that this endosymbiont might have a marked influence on the biology of the whole order. The presence of a related obligate nutritional bacterium in lice prevents the investigation of a causal link between sex ratio and endosymbionts. Conclusions Regardless of its origin, this sex ratio distortion in head lice that has been reported world wide, is stable over time and is a remarkable deviation from the stability of frequency-dependent selection of Fisher's sex ratio. A female bias first reported in 1898 is still present over a hundred years and a thousand generations later. PMID:15140268

  8. Can environmental or occupational hazards alter the sex ratio at birth? A systematic review

    PubMed Central

    Terrell, Metrecia L.; Hartnett, Kathleen P.; Marcus, Michele

    2011-01-01

    More than 100 studies have examined whether environmental or occupational exposures of parents affect the sex ratio of their offspring at birth. For this review, we searched Medline and Web of Science using the terms ‘sex ratio at birth’ and ‘sex ratio and exposure’ for all dates, and reviewed bibliographies of relevant studies to find additional articles. This review focuses on exposures that have been the subject of at least four studies including polychlorinated biphenyls (PCBs), dioxins, pesticides, lead and other metals, radiation, boron, and g-forces. For paternal exposures, only dioxins and PCBs were consistently associated with sex ratios higher or lower than the expected 1.06. Dioxins were associated with a decreased proportion of male births, whereas PCBs were associated with an increased proportion of male births. There was limited evidence for a decrease in the proportion of male births after paternal exposure to DBCP, lead, methylmercury, non-ionizing radiation, ionizing radiation treatment for childhood cancer, boron, or g-forces. Few studies have found higher or lower sex ratios associated with maternal exposures. Studies in humans and animals have found a reduction in the number of male births associated with lower male fertility, but the mechanism by which environmental hazards might change the sex ratio has not yet been established. PMID:24149027

  9. Sex ratio of equine offspring is affected by the ages of the mare and stallion.

    PubMed

    Santos, Marianna Machado; Maia, Leonardo Lara; Nobre, Daniel Magalhães; Oliveira Neto, José Ferraz; Garcia, Tiago Rezende; Lage, Maria Coeli Gomes Reis; de Melo, Maria Isabel Vaz; Viana, Walmir Santos; Palhares, Maristela Silveira; da Silva Filho, José Monteiro; Santos, Renato Lima; Valle, Guilherme Ribeiro

    2015-10-15

    The aim of this study was to determine the influence of parental age on the sex ratio of offspring in horses. Two trials were performed. In the first trial, the data from a randomly obtained population with a 1:1 sex ratio of 59,950 Mangalarga Marchador horses born in Brazil from 1990 to 2011 were analyzed. The sex ratios of the offspring were compared among groups according to the mare and the stallion ages (from 3 to 25 years). In the first step of the analysis, the mares and stallions were grouped according to age in 5-year intervals. In the second step, the groups were based on the parental age gap at conception. In the third step, the group of the mares and stallions with similar ages from the second step was subdivided, and the different parental age subgroups that were divided into 5-year intervals were compared. In the fourth step, the sex ratio of the offspring was determined according to the ages of the mares and the stallions at conception. The second trial was based on the data from 253 horses of several breeds that were born after natural gestation into a herd from 1989 to 2010, and the offspring of groups that were younger or older than 15 years were compared. The data from both trials were analyzed using a chi-square test (P ≤ 0.01 for the first trial; and P ≤ 0.05 for the second trial) for the comparisons of the sex ratios. In the first trial, the Spearman test (P ≤ 0.01) was used to verify the correlations between the parental age and the offspring sex ratio. In the first trial, the offspring sex ratio decreased as the mare or stallion age increased, and the decrease was more marked for the mares than for the stallions. In the second trial, the mares older than 15 years had more fillies than the younger mares, but the stallion age had no effect on the sex of the offspring. The first trial, with a large number of horses, revealed the pattern of the distribution of the sex ratios of offspring according to the parental age in horses, whereas the

  10. Brief Report: Parental Age and the Sex Ratio in Autism

    ERIC Educational Resources Information Center

    Anello, Alene; Reichenberg, Abraham; Luo, Xiaodong; Schmeidler, James; Hollander, Eric; Smith, Christopher J.; Puleo, Connor M.; Kryzak, Lauren A.; Silverman, Jeremy M.

    2009-01-01

    The male-to-female (M:F) ratio for autism spectrum disorders (ASD), typically about 4:1, appears to decrease with increasing paternal age, but this relationship has not been systematically tested. With 393 ASD cases from families with two or more ASD cases, we categorized paternal age into five age groups (less than 30, 30-34, 35-39, 40-44, 45+)…

  11. The impact of sex ratio and economic status on local birth rates.

    PubMed

    Chipman, A; Morrison, E

    2013-04-23

    Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female-female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction. PMID:23407502

  12. The Effects of Sex-Labelling on Adult-Infant Interactions.

    ERIC Educational Resources Information Center

    Armstrong, Suzy; Karr-Kidwell, PJ

    The influence of sex-labelling on adult-infant interactions is explored in this study. It is hypothesized that, when introduced to a single infant identified as either male or female, adults will (1) offer more masculine sex-stereotyped toys to the infant perceived to be male; (2) offer more feminine sex-stereotyped toys to the infant perceived to…

  13. Predicted sex ratio of juvenile Kemp's Ridley sea turtles captured near Steinhatchee, Florida

    USGS Publications Warehouse

    Geis, A.A.; Barichivich, W.J.; Wibbels, T.; Coyne, M.; Landry, A.M., Jr.; Owens, D.

    2005-01-01

    The Kemp's Ridley (Lepidochelys kempii) is one of the most endangered sea turtles in the world, and it possesses temperature-dependent sex determination (TSD). Sex ratios produced under TSD can vary widely and can affect the reproductive ecology of a population. Therefore, sex ratios produced from TSD are of ecological and conservation interest. The current study validated and utilized a testosterone radioimmunoassay (RIA) to examine the sex ratio of juvenile Kemp's Ridleys inhabiting the waters near Steinhatchee, Florida. Testosterone levels were measured in blood samples collected from juvenile Kemp's Ridleys captured over a three-year period. Results of this study indicate that a significant female bias (approximately 3.7:1) occurs in the aggregation of juvenile Kemp's Ridleys inhabiting the waters near Steinhatchee.

  14. Factors affecting sex ratio at birth in Croatia 1998-2008.

    PubMed

    Pavic, Dario

    2012-05-01

    This investigation aims to contribute to the existing literature on demographic and ecological factors affecting the sex ratio at birth, by analysing the births in Croatia from 1998 to 2008. Data from birth certificates for all Croatian births for the investigated period (n=420,256) were used to establish the link between parental ages, birth order, region of birth, parental occupation and parental education level, and sex of the child. The χ² test and t-test were used to assess the significance of each of the factors, along with multiple logistic regression to control for possible confounding effects. The results suggest that a joint higher age of both parents significantly lowers the sex ratio at birth. There is also a regional variation in sex ratio at birth, the lowest value being in Central Croatia and the highest in the City of Zagreb. Changes in the reproductive physiology of older parents are most probably responsible for the lower sex ratio, although the limited sample size warns against widespread generalizations. The causes of the regional variation in sex ratio at birth are most likely the different regional levels of obesity and physical inactivity. PMID:22225622

  15. Offspring sex ratio is related to paternal train elaboration and yolk corticosterone in peafowl.

    PubMed

    Pike, Thomas W; Petrie, Marion

    2005-06-22

    Several recent experimental studies have provided strong evidence for the ability of birds to manipulate the sex ratio of their offspring prior to laying. Using a captive population of peafowl (Pavo cristatus), we tested experimentally the effects of paternal attractiveness on offspring sex ratio, and related sex ratio deviations to egg-yolk concentrations of testosterone, 17beta-estradiol and corticosterone. When females were mated to males whose attractiveness had been experimentally reduced by removing prominent eyespot feathers from their trains, they produced significantly more female offspring, had significantly higher yolk corticosterone concentrations and tended to have lower levels of yolk testosterone than when mated to the same males with their full complement of feathers. Concentrations of 17beta-estradiol did not vary consistently with sex ratio biases. These findings add to the small number of studies providing experimental evidence that female birds can control the primary sex ratio of their offspring in response to paternal attractiveness, and highlight the possibility that corticosterone and perhaps testosterone are involved in the sex manipulation process in birds. PMID:17148167

  16. Does the changing sex ratio of multiple sclerosis give opportunities for intervention?

    PubMed

    Boström, I; Landtblom, A-M

    2015-01-01

    In several international studies, an increasing women-to-men (w/m) ratio in patients with multiple sclerosis (MS) has been reported. Such sex ratios have been analysed by year of onset or by year of birth. In a Swedish study, data from the Swedish MS register (SMSreg) were used to analyse the w/m ratio in Sweden. The sex ratio was analysed both by year of birth (8834 patients) and by year of onset (9098 patients). No increased w/m ratio was seen in this study. The age-specific sex ratio did not demonstrate any significant changes. However, a new investigation of the sex ratio in Sweden, based on data from all available data sources (19,510 patients), showed a significantly increased w/m ratio of MS in Sweden from 1.70 to 2.67. Environmental factors such as cigarette smoking, hormonal factors and nutrition are of interest in this context, but the cause of the increasing w/m ratio in MS is yet not possible to explain. PMID:26046558

  17. Childhood Attachment and Adult Attachment in Incarcerated Adult Male Sex Offenders.

    ERIC Educational Resources Information Center

    Smallbone, Stephen W.; Dadds, Mark R.

    1998-01-01

    Forty-eight incarcerated sex offenders were compared with 16 property offenders and 16 nonoffenders on self-report measures of childhood maternal and paternal attachment and adult attachment. Results suggest that insecure childhood attachments may be related to offending behavior generally and that certain combinations of childhood attachment…

  18. Do differences in Toxoplasma prevalence influence global variation in secondary sex ratio? Preliminary ecological regression study.

    PubMed

    Dama, Madhukar S; Martinec Nováková, Lenka; Flegr, Jaroslav

    2016-08-01

    Sex of the fetus is genetically determined such that an equal number of sons and daughters are born in large populations. However, the ratio of female to male births across human populations varies significantly. Many factors have been implicated in this. The theory that natural selection should favour female offspring under suboptimal environmental conditions implies that pathogens may affect secondary sex ratio (ratio of male to female births). Using regression models containing 13 potential confounding factors, we have found that variation of the secondary sex ratio can be predicted by seroprevalence of Toxoplasma across 94 populations distributed across African, American, Asian and European continents. Toxoplasma seroprevalence was the third strongest predictor of secondary sex ratio, β = -0·097, P < 0·01, after son preference, β = 0·261, P < 0·05, and fertility, β = -0·145, P < 0·001. Our preliminary results suggest that Toxoplasma gondii infection could be one of the most important environmental factors influencing the global variation of offspring sex ratio in humans. The effect of latent toxoplasmosis on public health could be much more serious than it is usually supposed to be. PMID:27350331

  19. Index and ring finger ratio--a morphologic sex determinant in South-Indian children.

    PubMed

    Kanchan, Tanuj; Pradeep Kumar, G

    2010-12-01

    To investigate the sexual dimorphism of index and ring finger ratio in South Indian children. The index finger length (IFL) and the ring finger length (RFL) were measured in 350 subjects aged between 2 and 12 years using a steel measuring tape. The index and ring finger ratio was computed by dividing index finger length by ring finger length. The data obtained were analyzed statistically using SPSS, version 11.0. Mean RFL was greater than mean IFL in both males and females. The mean ring finger length was longer in males than females and mean index finger length longer in females than males. However, these sex differences observed for index and ring finger length were not significant in both hands. Statistically significant sex differences were observed from the derived index and ring finger ratio. The mean index and ring finger ratio was found to be higher in females than males. Significant correlation was found between age and index and ring finger lengths. Index and ring finger ratio however, did not show any significant correlation with age. This study suggests that among South-Indian children, the index and ring finger ratio of 0.97 and less is indicative of male, and a ratio of more than 0.97 is indicative of female sex. The ratio can be a useful sex indicator irrespective of the age of the individual. PMID:20369311

  20. Inbreeding and Offspring Sex Ratio in the Pygmy Hippopotamus (Cheoropsis liberiensis) Population Kept in Zoological Gardens.

    PubMed

    Graczyk, Magdalena; Cwiertnia, Piotr; Borowska, Alicja; Barczak, Elżbieta; Szwaczkowski, Tomasz

    2015-01-01

    The aim of this study was to estimate the inbreeding level and its impact on offspring sex ratio in the pygmy hippopotamus population kept in zoological gardens. Records of pygmy hippopotamus born between 1873-2013 were extracted from the international studbook. Totally, 1357 individuals originating from 148 breeding units were included (individuals with unknown sex were omitted). The offspring sex ratio is defined as the number of sons to the total number of progeny of each dam and sire. Spearman's rank correlation was employed to examine the relationships between the inbreeding level and offspring sex ratio. Inbreeding coefficients and individual increase in inbreeding coefficients (included as a linear co-variable) were examined as well as the geographic region and birth period using general linear models. The average inbreeding coefficient was 5.39%. The following sex proportion was observed for the inbred population: 57% and 43% for females and males, respectively. A significant relationship between inbreeding level of parents and their offspring sex ratio were estimated for European zoological gardens, whereas in others geographic regions the dependencies were insignificant. PMID:26103683

  1. Sex Differences in Facial Scanning: Similarities and Dissimilarities between Infants and Adults

    ERIC Educational Resources Information Center

    Rennels, Jennifer L.; Cummings, Andrew J.

    2013-01-01

    When face processing studies find sex differences, male infants appear better at face recognition than female infants, whereas female adults appear better at face recognition than male adults. Both female infants and adults, however, discriminate emotional expressions better than males. To investigate if sex and age differences in facial scanning…

  2. Widespread vertical transmission and associated host sex-ratio distortion within the eukaryotic phylum Microspora.

    PubMed Central

    Terry, Rebecca S.; Smith, Judith E.; Sharpe, Rosie G.; Rigaud, Thierry; Littlewood, D. Timothy J.; Ironside, Joseph E.; Rollinson, David; Bouchon, Didier; MacNeil, Calum; Dick, Jaimie T. A.; Dunn, Alison M.

    2004-01-01

    Vertical transmission (VT) and associated manipulation of host reproduction are widely reported among prokaryotic endosymbionts. Here, we present evidence for widespread use of VT and associated sex-ratio distortion in a eukaryotic phylum. The Microspora are an unusual and diverse group of eukaryotic parasites that infect all animal phyla. Following our initial description of a microsporidian that feminizes its crustacean host, we survey the diversity and distribution of VT within the Microspora. We find that vertically transmitted microsporidia are ubiquitous in the amphipod hosts sampled and that they are also diverse, with 11 species of microsporidia detected within 16 host species. We found that infections were more common in females than males, suggesting that host sex-ratio distortion occurs in five out of eight parasite species tested. Phylogenetic reconstruction demonstrates that VT occurs in all major lineages of the phylum Microspora and that sex-ratio distorters are found on multiple branches of the phylogenetic tree. We propose that VT is either an ancestral trait or evolves with peculiar frequency in this phylum. If the association observed here between VT and host sex-ratio distortion holds true across other host taxa, these eukaryotic parasites may join the bacterial endosymbionts in their importance as sex-ratio distorters. PMID:15315893

  3. Calves' sex ratio in naturally and artificially bred cattle in central Ethiopia.

    PubMed

    Delesa, Effa Kefena; Yohannes, Aster; Alemayehu, Mengistu; Samuel, Temesgen; Yehualaeshet, Teshome

    2014-08-01

    A study was undertaken with the objective to identify some intrinsic (genotype of the cow, estrus time and parity) and extrinsic factors (service type, service time and estrus seasons) that affect calf sex ratio in naturally and artificially bred cattle in the central highlands of Ethiopia. A total of 4657 calving events were extracted from the long-term dairy cattle genetic improvement experiment at Holetta Agricultural Research Center. Factors that affect the logit of the probability of a female calf being born were obtained by using PROC GENMODE in Statistical Analysis System. Moreover, multivariate analysis was performed using PROC LOGISTIC procedure using forward selection procedure. Accordingly, genotype of the cow, parity, estrus season, and service type had considerable influences on calf sex ratio. However, estrus time and service time did not affect calf sex ratio (χ(2) = 0.83 and 0.79, respectively). In Ethiopia, smallholder dairy farmers often complain that artificial insemination (AI) skewed to producing more male calves. However, our study showed that AI did not alter female-to-male calf sex ratio. On the contrary, natural mating increases the probability of female calves born (odds ratio 1.38) over AI. Heifer/cows that showed estrus and bred during the harsh seasons of the years produced more female calves than those that bred during the good seasons of the year. This strongly agreed with Trivers and Willard sex allocation theory. PMID:24908336

  4. Sex role strain among kibbutz adolescents and adults: A developmental perspective.

    PubMed

    Snarey, J; Friedman, K; Blasi, J

    1986-06-01

    In spite of a commitment to equality, the kibbutz is a male-dominated society with highly differentiated sex roles. Has this gap between ideals and reality created sex role strain for kibbutz-born adolescents and adults? Previous kibbutz studies have suggested that sex role strain may be the most intense among adult kibbutz women. Based on Erik Erikson's developmental model, however, we hypothesized that adolescent females would experience significantly greater sex role strain than other kibbutz members, including adult women. Adolescent and adult males and females were tested using Loevinger's ego development test. The sex role items of the test were used to construct a new measure of sex role strain. The global index included the following submeasures: avoidance of sex role issues; expression of intellectual, emotional, or behavioral sex role conflict; and evaluative attitudes toward male roles and female roles. Significant cohort or sex differences were found on the global index and on all submeasures of sex role strain. The findings indicate that sex role strain is greatest among adolescent females, followed by adolescent males. Adult kibbutz women, however, are significantly more likely to focus their dissatisfaction in the area of actual role behavior rather than in terms of how they intellectually conceptualize kibbutz sex roles, as is the case for adolescents and adult males. PMID:24301699

  5. Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

    PubMed Central

    2013-01-01

    Background The ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature. Presentation of the hypothesis By the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation. Testing of the hypothesis A synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value < 0.0001. In Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value < 0.0001. The hypothesis may be tested by reconstruction of imports from the world markets to Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90. Implications of the hypothesis If the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations. PMID:23947741

  6. How do climate-linked sex ratios and dispersal limit range boundaries?

    PubMed Central

    2014-01-01

    Background Geographic ranges of ectotherms such as reptiles may be determined strongly by abiotic factors owing to causal links between ambient temperature, juvenile survival and individual sex (male or female). Unfortunately, we know little of how these factors interact with dispersal among populations across a species range. We used a simulation model to examine the effects of dispersal, temperature-dependent juvenile survival and sex determining mechanism (temperature-dependent sex determination (TSD) and genotypic sex determination (GSD)) and their interactions, on range limits in populations extending across a continuous range of air temperatures. In particular, we examined the relative importance of these parameters for population persistence to recommend targets for future empirical research. Results Dispersal influenced the range limits of species with TSD to a greater extent than in GSD species. Whereas male dispersal led to expanded species ranges across warm (female-producing) climates, female dispersal led to expanded ranges across cool (male-producing) climates. Two-sex dispersal eliminated the influence of biased sex ratios on ranges. Conclusion The results highlight the importance of the demographic parameter of sex ratio in determining population persistence and species range limits. PMID:25011492

  7. Disentangling the effect of genes, the environment and chance on sex ratio variation in a wild bird population.

    PubMed

    Postma, Erik; Heinrich, Franziska; Koller, Ursina; Sardell, Rebecca J; Reid, Jane M; Arcese, Peter; Keller, Lukas F

    2011-10-01

    Sex ratio theory proposes that the equal sex ratio typically observed in birds and mammals is the result of natural selection. However, in species with chromosomal sex determination, the same 1 : 1 sex ratio is expected under random Mendelian segregation. Here, we present an analysis of 14 years of sex ratio data for a population of song sparrows (Melospiza melodia) on Mandarte Island, at the nestling stage and at independence from parental care. We test for the presence of variance in sex ratio over and above the binomial variance expected under Mendelian segregation, and thereby quantify the potential for selection to shape sex ratio. Furthermore, if sex ratio variation is to be shaped by selection, we expect some of this extra-binomial variation to have a genetic basis. Despite ample statistical power, we find no evidence for the existence of either genetic or environmentally induced variation in sex ratio, in the nest or at independence. Instead, the sex ratio variation observed matches that expected under random Mendelian segregation. Using one of the best datasets of its kind, we conclude that female song sparrows do not, and perhaps cannot, adjust the sex of their offspring. We discuss the implications of this finding and make suggestions for future research. PMID:21345862

  8. Impaired imprinted X chromosome inactivation is responsible for the skewed sex ratio following in vitro fertilization.

    PubMed

    Tan, Kun; An, Lei; Miao, Kai; Ren, Likun; Hou, Zhuocheng; Tao, Li; Zhang, Zhenni; Wang, Xiaodong; Xia, Wei; Liu, Jinghao; Wang, Zhuqing; Xi, Guangyin; Gao, Shuai; Sui, Linlin; Zhu, De-Sheng; Wang, Shumin; Wu, Zhonghong; Bach, Ingolf; Chen, Dong-Bao; Tian, Jianhui

    2016-03-22

    Dynamic epigenetic reprogramming occurs during normal embryonic development at the preimplantation stage. Erroneous epigenetic modifications due to environmental perturbations such as manipulation and culture of embryos during in vitro fertilization (IVF) are linked to various short- or long-term consequences. Among these, the skewed sex ratio, an indicator of reproductive hazards, was reported in bovine and porcine embryos and even human IVF newborns. However, since the first case of sex skewing reported in 1991, the underlying mechanisms remain unclear. We reported herein that sex ratio is skewed in mouse IVF offspring, and this was a result of female-biased peri-implantation developmental defects that were originated from impaired imprinted X chromosome inactivation (iXCI) through reduced ring finger protein 12 (Rnf12)/X-inactive specific transcript (Xist) expression. Compensation of impaired iXCI by overexpression ofRnf12to up-regulateXistsignificantly rescued female-biased developmental defects and corrected sex ratio in IVF offspring. Moreover, supplementation of an epigenetic modulator retinoic acid in embryo culture medium up-regulatedRnf12/Xistexpression, improved iXCI, and successfully redeemed the skewed sex ratio to nearly 50% in mouse IVF offspring. Thus, our data show that iXCI is one of the major epigenetic barriers for the developmental competence of female embryos during preimplantation stage, and targeting erroneous epigenetic modifications may provide a potential approach for preventing IVF-associated complications. PMID:26951653

  9. Hypotheses on the stability and variation of human sex ratios at birth.

    PubMed

    James, William H

    2012-10-01

    Human sex ratios at birth simultaneously show both significant variation with a number of variables, and striking stability across time. Hypotheses on these features are discussed here. A) The causes of the stability are not established. B) There are several hypotheses which purport to explain sex ratio variation. 1. The Trivers–Willard hypothesis has had only limited success. This may be because (from a methodological standpoint) it has an unusual provenance in that it is not a response to a perceived need for explanation of an observed phenomenon. At present there seems too much evidence in its favour for this hypothesis to be rejected, and too much against it, for it to be accepted. 2. My hypothesis proposes that hormone concentrations (of both parents) around the time of conception partially control the sex of the zygote. A substantial quantity of data has been adduced in favour of this hypothesis. But it cannot explain all types of variation of sex ratios at birth. 3. It has been proposed by Catalano that other variation in sex ratios at birth is associated with maternal stress during pregnancy. He and his co-workers have adduced substantial quantities of data to support this hypothesis too. PMID:22776504

  10. Perspectives of Medical Interns Regarding Female Feticide and Declining Sex Ratio in India

    PubMed Central

    Avachat, Shubhada; Raut, Pritish; Zambare, Mrinal; Gund, Dilipkumar; Pundkar, Rutuja

    2013-01-01

    Background: Female feticide, skewed sex ratio, and its attendant social evils have grave ethical undertones for medical professionals and our commitment to save lives. A concerted effort by all is essential against female feticide. Aim: This study was to assess the knowledge of female feticide, declining sex ratio, and corrective measures among medical interns. Materials and Methods: A cross-sectional study was conducted among 79 medical interns. Data werecollected with the help of predesigned structured questionnaire. Chi-square tests, Kruskal-Wallis tests, and Z tests were used to test the significance level. Results: Knowledge of current sex ratio was significantly better among female interns than male interns. Majority of interns opined that creating awareness is an effective measure to combat declining sex ratio and only 33 interns had correct knowledge regarding all measures. Only 37.9% of interns knew all the legal indications for use of prenatal diagnostic techniques. However, 81% of interns were aware of punishments mentioned for violation of the Act. Mean score of knowledge was 22.06 among males and 24.4 among females. Conclusion: The findings in our study underline the need to sensitize doctors regardingevery aspect of Pre-Conception and Prenatal Diagnostic Techniques Act and selective sex determination. PMID:24083222

  11. Aggressive behavior of the male parent predicts brood sex ratio in a songbird

    NASA Astrophysics Data System (ADS)

    Szász, Eszter; Garamszegi, László Zsolt; Hegyi, Gergely; Szöllősi, Eszter; Markó, Gábor; Török, János; Rosivall, Balázs

    2014-08-01

    Brood sex ratio is often affected by parental or environmental quality, presumably in an adaptive manner that is the sex that confers higher fitness benefits to the mother is overproduced. So far, studies on the role of parental quality have focused on parental morphology and attractiveness. However, another aspect, the partner's behavioral characteristics, may also be expected to play a role in brood sex ratio adjustment. To test this hypothesis, we investigated whether the proportion of sons in the brood is predicted by the level of territorial aggression displayed by the father, in the collared flycatcher ( Ficedula albicollis). The proportion of sons in the brood was higher in early broods and increased with paternal tarsus length. When controlling for breeding date and body size, we found a higher proportion of sons in the brood of less aggressive fathers. Male nestlings are more sensitive to the rearing environment, and the behavior of courting males may often be used by females to assess their future parental activity. Therefore, adjusting brood sex ratio to the level of male aggression could be adaptive. Our results indicate that the behavior of the partner could indeed be a significant determinant in brood sex ratio adjustment, which should not be overlooked in future studies.

  12. Flock sizes and sex ratios of canvasbacks in Chesapeake Bay and North Carolina

    USGS Publications Warehouse

    Haramis, G.M.; Derleth, E.L.; Link, W.A.

    1994-01-01

    Knowledge of the distribution, size, and sex ratios of flocks of wintering canvasbacks (Aythya valisineria) is fundamental to understanding the species' winter ecology and providing guidelines for management. Consequently, in winter 1986-87, we conducted 4 monthly aerial photographic surveys to investigate temporal changes in distribution, size, and sex ratios of canvasback flocks in traditional wintering areas of Chesapeake Bay and coastal North Carolina. Surveys yielded 35mm imagery of 194,664 canvasbacks in 842 flocks. Models revealed monthly patterns of flock size in North Carolina and Virginia, but no pattern of change in Maryland. A stepwise analysis of flock size and sex ratio fit a common positive slope (increasing proportion male) for all state-month datasets, except for North Carolina in February where the slope was larger (P lt 0.001). State and month effects on intercepts were significant (P lt 0.001) and confirmed a previously identified latitudinal gradient in sex ratio in the survey region. There was no relationship between flock purity (% canvasbacks vs. other species) and flock size except in North Carolina in January, February, and March when flock purity was related to flock size. Contrasting characteristics in North Carolina with regard to flock size (larger flocks) and flock purity suggested that proximate factors were reinforcing flocking behavior and possibly species fidelity there. Of possible factors, the need to locate foraging sites within this large, open-water environment was hypothesized to be of primary importance. Comparison of January 1981 and 1987 sex ratios indicated no change in Maryland, but lower (P lt 0.05) canvasback sex ratios (proportion male) in Virginia and North Carolina.

  13. Analysis of the sex ratio of reported gonorrhoea incidence in Shenzhen, China

    PubMed Central

    Xiong, Mingzhou; Lan, Lina; Feng, Tiejian; Zhao, Guanglu; Wang, Feng; Hong, Fuchang; Wu, Xiaobing; Zhang, Chunlai; Wen, Lizhang; Liu, Aizhong; Best, John McCulloch; Tang, Weiming

    2016-01-01

    Objective To assess the clinical process of gonorrhoea diagnosis and report in China, and to determine the difference of sex ratio between reported incidence based on reporting data and true diagnosis rate based on reference tests of gonorrhoea. Setting A total of 26 dermatology and sexually transmitted disease (STD) departments, 34 obstetrics-gynaecology clinics and 28 urology outpatient clinics selected from 34 hospitals of Shenzhen regarded as our study sites. Participants A total of 2754 participants were recruited in this study, and 2534 participants completed the questionnaire survey and provided genital tract secretion specimens. There were 1106 male and 1428 female participants. Eligible participants were patients who presented for outpatient STD care at the selected clinics for the first time in October 2012 were at least 18 years old, and were able to give informed consent. Outcome measures Untested rate, true-positive rate, false-negative rate and unreported rate of gonorrhoea, as well as reported gonorrhoea incidence sex ratio and true diagnosis sex ratio were calculated and used to describe the results. Results 2534 participants were enrolled in the study. The untested rate of gonorrhoea among females was significantly higher than that among males (female 88.1%, male 68.3%, p=0.001). The male-to-female sex ratios of untested rate, true-positive rate, false-negative rate and unreported rate were 1:1.3, 1.2:1, 1:1.6 and 1:1.4, respectively. The reported gonorrhoea incidence sex ratio of new diagnosed gonorrhoea was 19.8:1 (male vs female: 87/1106 vs 5/1420), while the true diagnosis sex ratio was 2.5:1 (male vs female: 161/1106 vs 84/1420). These data indicate that the sex ratio of reported gonorrhoea incidence has been overestimated by a factor of 7.9 (19.8/2.5). Conclusions We found the current reported gonorrhoea incidence and sex ratios to be inaccurate due to underestimations of gonorrhoea incidence, especially among women. PMID:26975933

  14. Anxiety, sex-linked behaviors, and digit ratios (2D:4D).

    PubMed

    Evardone, Milagros; Alexander, Gerianne M

    2009-06-01

    The second to fourth (2D:4D) digit ratio, a sexually dimorphic, phenotypic characteristic putatively associated with perinatal androgen action, has been used to evaluate the hypothesized relation between prenatal hormonal factors and a variety of sexually dimorphic behaviors, including sex-linked psychopathology. Smaller digit ratios, suggestive of stronger perinatal androgen action, have been associated with male-linked disorders (e.g., autism), and larger digit ratios, suggestive of weaker perinatal androgen action, have been associated with female-linked disorders (e.g., depression and eating disorders). To evaluate the possible relation between digit ratio and another traditionally female-linked disorder, anxiety, 2D:4D ratios were measured in a non-clinical sample (58 men, 52 women). Participants also completed a battery of anxiety and gender role measures and performed two spatial/cognitive tasks typically showing a male advantage (mental rotation and targeting) and two tasks typically showing a female advantage (location memory and spatial working memory). Men with a more feminine pattern of sex-linked traits and behaviors (including digit ratios) reported greater anxiety. In contrast, greater anxiety in women was associated with both female-typical and male-typical traits and behaviors, but and no significant association between digit ratio and anxiety was found. This pattern of results suggests that the development of anxiety is multiply determined, with contributing factors varying by sex. PMID:17943431

  15. Sex Differences in the Association Between Birth Weight and Adult Type 2 Diabetes.

    PubMed

    Zimmermann, Esther; Gamborg, Michael; Sørensen, Thorkild I A; Baker, Jennifer L

    2015-12-01

    Low birth weight is a well-established risk factor for type 2 diabetes, but the risk at high birth weight levels remains uncertain. Potential sex differences in the associations are unexplored. We investigated whether sex influences the association of birth weight and adult type 2 diabetes, using a cohort of 113,801 men and 109,298 women, born 1936-1983, from the Copenhagen School Health Records Register, Denmark. During 5.6 million person-years of follow-up, 7,750 men and 4,736 women had a diagnosis of adult type 2 diabetes (30 years of age or older) obtained from national registers. When birth weights between 3.251 and 3.750 kg were used as the reference group for each sex separately, women with birth weights in the categories of 2.000 to 2.750 kg and 4.751 to 5.500 kg had hazard ratios [HRs] of type 2 diabetes of 1.46 (95% CI, 1.34-1.59) and 1.56 (1.20-2.04), respectively, whereas men had HRs of 1.20 (1.12-1.30) and 0.93 (0.76-1.15). Thus, sex modified the association, with stronger risk estimates of type 2 diabetes in women at both low and high birth weights compared with men (P = 0.001). In conclusion, birth weight is more strongly associated with type 2 diabetes in women than in men. Future search for sex-specific causal mechanisms may provide new insights into the early origins of type 2 diabetes. PMID:26253610

  16. Simultaneous failure of two sex-allocation invariants: implications for sex-ratio variation within and between populations

    PubMed Central

    Rodrigues, António M. M.; Gardner, Andy

    2015-01-01

    Local mate competition (LMC) occurs when male relatives compete for mating opportunities, and this may favour the evolution of female-biased sex allocation. LMC theory is among the most well developed and empirically supported topics in behavioural ecology, clarifies links between kin selection, group selection and game theory, and provides among the best quantitative evidence for Darwinian adaptation in the natural world. Two striking invariants arise from this body of work: the number of sons produced by each female is independent of both female fecundity and also the rate of female dispersal. Both of these invariants have stimulated a great deal of theoretical and empirical research. Here, we show that both of these invariants break down when variation in female fecundity and limited female dispersal are considered in conjunction. Specifically, limited dispersal of females following mating leads to local resource competition (LRC) between female relatives for breeding opportunities, and the daughters of high-fecundity mothers experience such LRC more strongly than do those of low-fecundity mothers. Accordingly, high-fecundity mothers are favoured to invest relatively more in sons, while low-fecundity mothers are favoured to invest relatively more in daughters, and the overall sex ratio of the population sex ratio becomes more female biased as a result. PMID:26085590

  17. Comparison of Isokinetic Hip Abduction and Adduction Peak Torques and Ratio Between Sexes

    PubMed Central

    Sugimoto, Dai; Mattacola, Carl G.; Mullineaux, David R.; Palmer, Thomas G.; Hewett, Timothy E.

    2014-01-01

    Objective To evaluate hip abductor and adductor peak torque outputs and compare their ratios between sexes. Design A cross-sectional laboratory-controlled study. Setting Participants visited a laboratory and performed an isokinetic hip abductor and adductor test. All participants performed 2 sets of 5 repetitions of concentric hip abduction and adduction in a standing position at 60 degrees per second. Gravity was determined as a function of joint angle relative to the horizontal plane and was corrected by normalizing the weight of the limb on an individual basis. Participants A total of 36 collegiate athletes. Independent Variable Sex (20 females and 16 males). Main Outcome Measures Bilateral peak hip abductor and adductor torques were measured. The 3 highest peak torque values were averaged for each subject. Results Independent t tests were used to compare sex differences in hip abductor and adductor peak torques and the abductor:adductor peak torque ratios. Males demonstrated significantly greater hip abductor peak torque compared with females (males 1.29 ± 0.24 Nm/kg, females 1.13 ± 0.20 Nm/kg; P = 0.03). Neither hip adductor peak torque nor their ratios differed between sexes. Conclusions Sex differences in hip abductor strength were observed. The role of weaker hip abductors in females deserves further attention and may be a factor for higher risk of knee pathologies. PMID:24905541

  18. Maternal Condition Does Not Influence Birth Sex Ratios in Anubis Baboons (Papio anubis)

    PubMed Central

    Silk, Joan B.; Strum, Shirley C.

    2010-01-01

    Trivers and Willard predicted that when parental condition has differential effects on the fitness of male and female offspring, parents who are in good condition will bias investment toward the sex that benefits most from additional investment. Efforts to test predictions derived from Trivers and Willard's model have had mixed results, perhaps because most studies have relied on proxy measures of parental condition, such as dominance rank. Here, we examine the effects of female baboons condition on birth sex ratios and post-natal investment, based on visual assessments of maternal body condition. We find that local environmental conditions have significant effects on female condition, but maternal condition at conception has no consistent relationship with birth sex ratios. Mothers who are in poorer condition at the time of conception resume cycling significantly later than females who are in better condition, but the sex of their infants has no effect on the time to resumption of cycling. Thus, our findings provide strong evidence that maternal condition influences females' ability to reproduce, but females do not facultatively adjust the sex ratio of their offspring in relation to their dominance rank or current condition. PMID:20877648

  19. Sex-Specific Arrival Times on the Breeding Grounds: Hybridizing Migratory Skuas Provide Empirical Support for the Role of Sex Ratios.

    PubMed

    Lisovski, Simeon; Fröhlich, Anne; von Tersch, Matthew; Klaassen, Marcel; Peter, Hans-Ulrich; Ritz, Markus S

    2016-04-01

    In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio. PMID:27028080

  20. Sex differences in the risk of receiving potentially inappropriate prescriptions among older adults

    PubMed Central

    Morgan, Steven G.; Weymann, Deirdre; Pratt, Brandy; Smolina, Kate; Gladstone, Emilie J.; Raymond, Colette; Mintzes, Barbara

    2016-01-01

    Objectives: to measure sex differences in the risk of receiving potentially inappropriate prescription drugs and to examine what are the factors that contribute to these differences. Design: a retrospective cohort study. Setting: community setting of British Columbia, Canada. Participants: residents of British Columbia aged 65 and older (n = 660,679). Measurements: we measured 2013 period prevalence of prescription dispensations satisfying the American Geriatrics Society's 2012 version of the Beers Criteria for potentially inappropriate medication use in older adults. We used logistic regressions to test for associations between this outcome and a number of clinical and socioeconomic factors. Results: a larger share of women (31%) than of men (26%) filled one or more potentially inappropriate prescription in the community. The odds of receiving potentially inappropriate prescriptions are associated with several clinical and socioeconomic factors. After controlling for those factors, community-dwelling women were at 16% higher odds of receiving a potentially inappropriate prescription than men (adjusted odds ratio = 1.16, 95% confidence interval = 1.12–1.21). Much of this sex difference stemmed from women's increased odds of receiving potentially inappropriate prescriptions for benzodiazepines and other hypnotics, for tertiary tricyclic antidepressants and for non-selective NSAIDs. Conclusion: there are significant sex differences in older adults' risk of receiving a potentially inappropriate prescription as a result of complex intersections between gender and other social constructs. Appropriate responses will therefore require changes in the information, norms and expectations of both prescribers and patients. PMID:27151390

  1. Sex ratios and sexual dimorphism among recently transformed sea lampreys, Petromyzon marinus Linnaeus

    USGS Publications Warehouse

    Applegate, Vernon C.; Thomas, M.L.H.

    1965-01-01

    The sex, length, and weight were determined of nearly all recently transformed sea lampreys migrating downstream in the Carp Lake River, Michigan, in the fall, winter, and spring of 1960-61. Similar data were collected from samples of an earlier run in the Carp Lake River and of runs in three other tributaries of Lakes Huron and Michigan. The sex ratio of the 1960-61 migrants in the Carp Lake River was 324 males:100 females. Sex ratios of migrants in the other runs varied from 77 to 86 males:100 females. The high proportion of males in the 1960-61 run in the Carp Lake River is attributed to the effective prevention of recruitment of sea lampreys in the river and transformation of the females at an earlier age than is characteristic of the males. A near equal sex ratio among recently transformed migrants is considered normal for the species. The sex composition of a run changed during the period of migration. The proportion of males among the migrants was greatest at the beginning of the run and declined steadily thereafter. The average size was smaller for males than for females. Differences in the mean lengths and weights of the sexes were statistically significant. The length-weight relation differed for the sexes and showed a slower rate of increase of weight with increase in length than is characteristic of other stages of the animals' life cycle. Seasonal changes in the length-weight relation had a trend toward lower weights among the migrants coming downstream in the later months of the run.

  2. Sequence Analysis of the Segmental Duplication Responsible for Paris Sex-Ratio Drive in Drosophila simulans

    PubMed Central

    Fouvry, Lucie; Ogereau, David; Berger, Anne; Gavory, Frederick; Montchamp-Moreau, Catherine

    2011-01-01

    Sex-ratio distorters are X-linked selfish genetic elements that facilitate their own transmission by subverting Mendelian segregation at the expense of the Y chromosome. Naturally occurring cases of sex-linked distorters have been reported in a variety of organisms, including several species of Drosophila; they trigger genetic conflict over the sex ratio, which is an important evolutionary force. However, with a few exceptions, the causal loci are unknown. Here, we molecularly characterize the segmental duplication involved in the Paris sex-ratio system that is still evolving in natural populations of Drosophila simulans. This 37.5 kb tandem duplication spans six genes, from the second intron of the Trf2 gene (TATA box binding protein-related factor 2) to the first intron of the org-1 gene (optomotor-blind-related-gene-1). Sequence analysis showed that the duplication arose through the production of an exact copy on the template chromosome itself. We estimated this event to be less than 500 years old. We also detected specific signatures of the duplication mechanism; these support the Duplication-Dependent Strand Annealing model. The region at the junction between the two duplicated segments contains several copies of an active transposable element, Hosim1, alternating with 687 bp repeats that are noncoding but transcribed. The almost-complete sequence identity between copies made it impossible to complete the sequencing and assembly of this region. These results form the basis for the functional dissection of Paris sex-ratio drive and will be valuable for future studies designed to better understand the dynamics and the evolutionary significance of sex chromosome drive. PMID:22384350

  3. Organization of the sex-ratio Meiotic Drive Region in Drosophila simulans

    PubMed Central

    Montchamp-Moreau, Catherine; Ogereau, David; Chaminade, Nicole; Colard, Alexandre; Aulard, Sylvie

    2006-01-01

    Sex-ratio meiotic drive is the preferential transmission of the X chromosome by XY males, which occurs in several Drosophila species and results in female-biased progeny. Although the trait has long been known to exist, its molecular basis remains completely unknown. Here we report a fine-mapping experiment designed to characterize the major drive locus on a sex-ratio X chromosome of Drosophila simulans originating from the Seychelles (XSR6). This primary locus was found to contain two interacting elements at least, both of which are required for drive expression. One of them was genetically tracked to a tandem duplication containing six annotated genes (Trf2, CG32712, CG12125, CG1440, CG12123, org-1), and the other to a candidate region located ∼110 kb away and spanning seven annotated genes. RT–PCR showed that all but two of these genes were expressed in the testis of both sex-ratio and standard males. In situ hybridization to polytene chromosomes revealed a complete association of the duplication with the sex-ratio trait in random samples of X chromosomes from Madagascar and Reunion. PMID:16387875

  4. Too Many Men? Sex Ratios and Women's Partnering Behavior in China

    ERIC Educational Resources Information Center

    Trent, Katherine; South, Scott J.

    2011-01-01

    The relative numbers of women and men are changing dramatically in China, but the consequences of these imbalanced sex ratios have received little empirical attention. We merge data from the Chinese Health and Family Life Survey with community-level data from Chinese censuses to examine the relationship between cohort- and community-specific sex…

  5. Non-quantitative adjustment of offspring sex ratios in pollinating fig wasps

    PubMed Central

    Wang, Rui-Wu; Sun, Bao-Fa; He, Jun-Zhou; Dunn, Derek W.

    2015-01-01

    Fig wasp is one of the most well known model systems in examining whether or not the parents could adjust their offspring sex ratio to maximize their gene frequency transmission in next generations. Our manipulative experiments showed that, in all of the five pollinator wasps of figs (Agaonidae) that have different averages of foundress numbers per syconium, almost the same proportions of male offspring are produced in the experiment that foundresses deposit one hour then are killed with ether (66.1%–70.1%) and over the lifespan of each foundress (14.0%–21.0%). The foundresses tend to deposit their male eggs prior to female eggs. The observed increase in the proportion of male offspring as a function of foundress number results from density-dependent interference competition among the foundresses. These results showed that the selection of gene frequency transmission through the behavioral adjustment in the evolution of sex ratio does not exist in these five fig wasps. The results here implied that genetic adjustment mechanisms of the sex ratio of fig wasps can only be triggered to be on or off and that the foundresses can not quantitatively adjust their sex ratio according to increased environmental selection pressure. PMID:26293349

  6. Lunar cycles at mating do not influence sex ratio at birth in horses.

    PubMed

    Aguilar, J J; Cuervo-Arango, J; Santa Juliana, L

    2015-02-01

    It is scientifically demonstrated that lunar cycles have important effects on several biological events. Controversy exists about the lunar influence on human and animal parturition. In addition, in the horse industry, especially in Polo Horse breeders of Argentina and around the world there is a higher demand for female offspring than for males. The objective of this study was to determine whether there is a significant association between the lunar phase at the time of mating and the sex ratio at birth in horses. The Argentinean Stud Book provided information related to all matings registered for Thoroughbred and Arab horses between 2003 and 2011. Statistical associations were tested between dates of matings at different lunar phases or days and sex ratio at birth. A total of 65.535 gestations were studied. Overall, sex ratio at birth resulted in 33.396 fillies (50.96%) and 32.139 colts (49.04%). The percentages of males and females at birth were not statistically different amongst the different lunar phases or days. We can strongly conclude that managing the breeding dates in relation to lunar cycles in order to manipulate the sex ratio of the offspring is not a viable option in horses. PMID:25153135

  7. Sex Ratio at Birth and Infant Mortality Rate in China: An Empirical Study

    ERIC Educational Resources Information Center

    Lai, Denjian

    2005-01-01

    In this article, we used the data from the last three population censuses of China in 1982, 1990 and 2000, to study the dynamics of the sex ratio at birth and the infant mortality rate in China. In the late 1970s, China started its economic reform and implemented many family planning programs. Since then there has been great economic development…

  8. Does polyandry control population sex ratio via regulation of a selfish gene?

    PubMed Central

    Price, Tom A. R.; Bretman, Amanda; Gradilla, Ana C.; Reger, Julia; Taylor, Michelle L.; Giraldo-Perez, Paulina; Campbell, Amy; Hurst, Gregory D. D.; Wedell, Nina

    2014-01-01

    The extent of female multiple mating (polyandry) can strongly impact on the intensity of sexual selection, sexual conflict, and the evolution of cooperation and sociality. More subtly, polyandry may protect populations against intragenomic conflicts that result from the invasion of deleterious selfish genetic elements (SGEs). SGEs commonly impair sperm production, and so are likely to be unsuccessful in sperm competition, potentially reducing their transmission in polyandrous populations. Here, we test this prediction in nature. We demonstrate a heritable latitudinal cline in the degree of polyandry in the fruitfly Drosophila pseudoobscura across the USA, with northern population females remating more frequently in both the field and the laboratory. High remating was associated with low frequency of a sex-ratio-distorting meiotic driver in natural populations. In the laboratory, polyandry directly controls the frequency of the driver by undermining its transmission. Hence we suggest that the cline in polyandry represents an important contributor to the cline in sex ratio in nature. Furthermore, as the meiotic driver causes sex ratio bias, variation in polyandry may ultimately determine population sex ratio across the USA, a dramatic impact of female mating decisions. As SGEs are ubiquitous it is likely that the reduction of intragenomic conflict by polyandry is widespread. PMID:24695427

  9. Cognitive Distortions and Blame Attribution in Sex Offenders against Adults and Children.

    ERIC Educational Resources Information Center

    Blumenthal, Stephen; Gudjonsson, Gisli; Burns, Jan

    1999-01-01

    This study compared sex offenders against children and adults on measures of cognitive distortions relating to sex with children and rape and a measure of blame attribution. Child sexual offenders endorsed more cognitive distortions relating to sex with children and reported more guilt-feeling attributions. (Author/DB)

  10. The effect of glucosamine concentration on the development and sex ratio of bovine embryos.

    PubMed

    Kimura, Koji; Iwata, Hisataka; Thompson, Jeremy G

    2008-01-30

    Glucosamine is a component of hyaluronic acid and an alternative substrate to glucose for the extracellular matrix synthesis of COCs. Its addition to an IVM medium reduces the glucose consumption of bovine COCs. Glucosamine is also metabolized to UDP-N-acetyl glucosamine (UDP-GlcNAc) via the hexosamine biosynthesis pathway and is utilized for O-linked glycosylation by the X-linked enzyme, O-linked GlcNAc transferase (OGT). Moreover, the inactivation of the second X chromosome in female embryos is influential in producing the sex ratio bias observed in vitro when embryos are cultured in the presence of glucose above 2.5mM. Accordingly, the aim of this study is to examine whether the presence of glucosamine during maturation or embryo culture causes a sex ratio bias in bovine blastocysts. Glucosamine was added to the medium in three different embryo developmental periods: in vitro maturation, the one-cell to eight-cell stage (before the maternal-zygotic transition, MZT), and the eight-cell to blastocyst stage (after MZT). When glucosamine was added during in vitro maturation, the developmental competence of oocytes was severely compromised. However, the sex ratio of embryos was not influenced. When glucosamine was added to embryo culture medium during development from one-cell to eight-cell stage (before MZT), it affected neither the development nor the sex ratio of bovine embryos. Finally, when glucosamine was added after MZT, the development rate of embryos was severely decreased, and the sex ratio was skewed toward males. Moreover, an inhibitor of OGT, benzyl-2-acetamido-2-deoxy-alpha-D-galactopyranoside (BADGP), negated the effect of glucosamine on the sex ratio when it was added to embryo culture medium from the eight-cell to blastocyst stage (after MZT). These results suggest that, like glucose, the supplementation of glucosamine into the medium skewed the sex ratio to males and that OGT, an X-linked enzyme, was involved in this phenomenon. Moreover, this

  11. Children's and Adults' Recall of Sex-Stereotyped Toy Pictures: Effects of Presentation and Memory Task

    ERIC Educational Resources Information Center

    Cherney, Isabelle D.

    2005-01-01

    Gender schema theories predict a memory bias toward sex-congruent information. The present study examined how presentation of stimuli and encoding conditions influence gender schematic processing in children and adults. One hundred and sixty 5- to 13-year olds and adult males and females viewed 36 sex-stereotyped toy pictures that were presented…

  12. A Review of "Older, Wiser, Sexually Smarter: 30 Sex Ed Lessons for Adults Only"

    ERIC Educational Resources Information Center

    Garrity, Joan Mogul

    2010-01-01

    While virtually all sex ed curricula are designed to be used with children, teens and young adults, "Older, Wiser, Sexually Smarter: 30 Sex Ed Lessons for Adults Only" ([C] 2009, Planned Parenthood of Greater Northern New Jersey) offers lessons to help participants fully embrace the possibility of sexual pleasure and intimacy from mid-life through…

  13. Limiting options: Sex ratios, incarceration rates and sexual risk behavior among people on probation and parole

    PubMed Central

    Green, Traci C.; Pouget, Enrique R.; Harrington, Magdalena; Taxman, Faye S.; Rhodes, Anne G.; O’Connell, Daniel; Martin, Steven S.; Prendergast, Michael; Friedmann, Peter D.

    2012-01-01

    Background To investigate how incarceration may affect risk of acquiring HIV and other sexually transmitted infections, we tested associations of ex-offenders’ sexual risk behavior with the male-female sex ratio and the male incarceration rate. Methods Longitudinal data from 1287 drug-involved persons on probation and parole as part of the Criminal Justice Drug Abuse Treatment Studies were matched by county of residence with population factors, and stratified by race/ethnicity and gender. Generalized estimating equations assessed associations of having unprotected sex with a partner who had HIV risk factors, and having more than 1 sex partner in the past month. Results Among non-Hispanic Black men and women, low sex ratios were associated with greater risk of having unprotected sex with a risky partner (Adjusted relative risk (ARR) = 1.76, 95% confidence interval (CI) = 1.29, 2.42; ARR = 2.48, 95% CI = 1.31, 4.73, respectively). Among non-Hispanic Black and non-Hispanic White women, low sex ratios were associated with having more than 1 sex partner (ARR = 2.00, 95% CI = 1.02, 3.94; ARR = 1.71, 95% CI = 1.06, 2.75, respectively). High incarceration rates were associated with greater risk of having a risky partner for all men (non-Hispanic Black: ARR= 2.14, 95% CI=1.39, 3.30; non-Hispanic White: ARR= 1.39, 95% CI: 1.05, 1.85; Hispanic: ARR = 3.99, 95% CI =1.55, 10.26) and having more than one partner among non-Hispanic White men (ARR= 1.92, 95% CI = 1.40, 2.64). Conclusions Low sex ratios and high incarceration rates may influence the number and risk characteristics of sex partners of ex-offenders. HIV-prevention policies and programs for ex-offenders could be improved by addressing structural barriers to safer sexual behavior. PMID:22592827

  14. Son-Killer: A Third Extrachromosomal Factor Affecting the Sex Ratio in the Parasitoid Wasp, NASONIA (=MORMONIELLA) VITRIPENNIS

    PubMed Central

    Skinner, Samuel Way

    1985-01-01

    An extrachromosomal factor, termed son-killer (sk), affects the sex ratio in a parasitoid wasp, Nasonia (=Mormoniella ) vitripennis. The factor is maternally transmitted and alters the secondary sex ratio of an infected female through mortality of approximately 80% of the male embryos. No effect on the primary (zygotic) sex ratio is observed. Ninety-five percent of the daughters of an infected female inherit son-killer. The factor can also be transmitted contagiously when the progeny of infected and uninfected females develop simultaneously on a single host. In newly infected strains, the sex ratio effects are equivalent to those in the original. PMID:3988039

  15. Self-regulatory driving practices among older adults: health, age and sex effects.

    PubMed

    Kostyniuk, Lidia P; Molnar, Lisa J

    2008-07-01

    The purpose of this study was to better understand how older adults self-regulate driving, and to identify differences by age, sex, and health-related functioning. Michigan drivers over age 64 were surveyed by telephone (n=961, age [mu=74.2, sigma=5.8], 56% female) about their driving-related behaviors, physical functioning, and health. Respondents were presented with scenarios involving driving to an important appointment under adverse conditions (rainy stormy weather, on alternate route in heavy freeway traffic, 200-mile trip on unfamiliar roads). Generalized logit models examined outcomes for each scenario: driving as usual, driving with modifications, and not driving. Results indicate that the effect of sex on self-regulation was significant and greater than that of age and physical functioning. Women were more likely to self-regulate by not driving. Odds ratios and 95% confidence limits for each scenario for women vs. men are 6.8 (3.8-2.0), 6.5 (3.6-12.0), and 17.7 (11.0-28.6). The effect of sex on self-regulation by modifying driving was smaller and significant only in scenarios 2 and 3. Women were more likely then men to modify driving for scenario 2 (odds ratio, 3.0 (2.0-4.5)) and scenario 3 (odds ratio 4.4 (3.1-0.1)). Overall, the study finds the relative effect of sex on self-regulation greater than that of age and physical functioning for conditions examined. PMID:18606292

  16. Female-Bias in a Long-Term Study of a Species with Temperature-Dependent Sex Determination: Monitoring Sex Ratios for Climate Change Research.

    PubMed

    Braun McNeill, Joanne; Avens, Larisa; Goodman Hall, April; Goshe, Lisa R; Harms, Craig A; Owens, David W

    2016-01-01

    Alterations have occurred and continue to manifest in the Earth's biota as a result of climate change. Animals exhibiting temperature dependent sex determination (TSD), including sea turtles, are perhaps most vulnerable to a warming of the Earth as highly skewed sex ratios can result, potentially leading to population extinction resulting from decreased male recruitment. Recent studies have begun to quantify climate change impacts to sea turtle populations, especially in terms of predicting effects on hatchling sex ratios. However, given the inherent difficulty in studying sex ratios at this life stage, a more accurate assessment of changes in population sex ratios might be derived by evaluating the juvenile portion of foraging aggregations. We investigated the long-term trend in sex ratio of a juvenile loggerhead (Caretta caretta) sea turtle population inhabiting Pamlico and Core Sounds, North Carolina, USA. We used plasma testosterone reference ranges measured using radioimmunoassay (RIA) to assign sex for 959 turtles and confirmed sex assignment of a subset (N = 58) of the sampled turtles through laparoscopic examination of their gonads. Our results demonstrate that for this particular population of loggerheads, sex ratios (3Females:1Male) had not significantly changed over a 10 year period (1998-2007), nor showed any significant difference among 5-cm straight carapace length (SCL) size classes. Ultimately, these findings provide a basis for comparison with future sex ratios, and highlight the importance of establishing similar long-term studies monitoring secondary, rather than primary, sex ratios, so that needed mitigation measures to climate change impacts can be implemented. PMID:27579608

  17. Temporal variability of local abundance, sex ratio and activity in the Sardinian chalk hill blue butterfly

    USGS Publications Warehouse

    Casula, P.; Nichols, J.D.

    2003-01-01

    When capturing and marking of individuals is possible, the application of newly developed capture-recapture models can remove several sources of bias in the estimation of population parameters such as local abundance and sex ratio. For example, observation of distorted sex ratios in counts or captures can reflect either different abundances of the sexes or different sex-specific capture probabilities, and capture-recapture models can help distinguish between these two possibilities. Robust design models and a model selection procedure based on information-theoretic methods were applied to study the local population structure of the endemic Sardinian chalk hill blue butterfly, Polyommatus coridon gennargenti. Seasonal variations of abundance, plus daily and weather-related variations of active populations of males and females were investigated. Evidence was found of protandry and male pioneering of the breeding space. Temporary emigration probability, which describes the proportion of the population not exposed to capture (e.g. absent from the study area) during the sampling process, was estimated, differed between sexes, and was related to temperature, a factor known to influence animal activity. The correlation between temporary emigration and average daily temperature suggested interpreting temporary emigration as inactivity of animals. Robust design models were used successfully to provide a detailed description of the population structure and activity in this butterfly and are recommended for studies of local abundance and animal activity in the field.

  18. A CRISPR-Cas9 sex-ratio distortion system for genetic control

    PubMed Central

    Galizi, Roberto; Hammond, Andrew; Kyrou, Kyros; Taxiarchi, Chrysanthi; Bernardini, Federica; O’Loughlin, Samantha M.; Papathanos, Philippos-Aris; Nolan, Tony; Windbichler, Nikolai; Crisanti, Andrea

    2016-01-01

    Genetic control aims to reduce the ability of insect pest populations to cause harm via the release of modified insects. One strategy is to bias the reproductive sex ratio towards males so that a population decreases in size or is eliminated altogether due to a lack of females. We have shown previously that sex ratio distortion can be generated synthetically in the main human malaria vector Anopheles gambiae, by selectively destroying the X-chromosome during spermatogenesis, through the activity of a naturally-occurring endonuclease that targets a repetitive rDNA sequence highly-conserved in a wide range of organisms. Here we describe a CRISPR-Cas9 sex distortion system that targets ribosomal sequences restricted to the member species of the Anopheles gambiae complex. Expression of Cas9 during spermatogenesis resulted in RNA-guided shredding of the X-chromosome during male meiosis and produced extreme male bias among progeny in the absence of any significant reduction in fertility. The flexibility of CRISPR-Cas9 combined with the availability of genomic data for a range of insects renders this strategy broadly applicable for the species-specific control of any pest or vector species with an XY sex-determination system by targeting sequences exclusive to the female sex chromosome. PMID:27484623

  19. A CRISPR-Cas9 sex-ratio distortion system for genetic control.

    PubMed

    Galizi, Roberto; Hammond, Andrew; Kyrou, Kyros; Taxiarchi, Chrysanthi; Bernardini, Federica; O'Loughlin, Samantha M; Papathanos, Philippos-Aris; Nolan, Tony; Windbichler, Nikolai; Crisanti, Andrea

    2016-01-01

    Genetic control aims to reduce the ability of insect pest populations to cause harm via the release of modified insects. One strategy is to bias the reproductive sex ratio towards males so that a population decreases in size or is eliminated altogether due to a lack of females. We have shown previously that sex ratio distortion can be generated synthetically in the main human malaria vector Anopheles gambiae, by selectively destroying the X-chromosome during spermatogenesis, through the activity of a naturally-occurring endonuclease that targets a repetitive rDNA sequence highly-conserved in a wide range of organisms. Here we describe a CRISPR-Cas9 sex distortion system that targets ribosomal sequences restricted to the member species of the Anopheles gambiae complex. Expression of Cas9 during spermatogenesis resulted in RNA-guided shredding of the X-chromosome during male meiosis and produced extreme male bias among progeny in the absence of any significant reduction in fertility. The flexibility of CRISPR-Cas9 combined with the availability of genomic data for a range of insects renders this strategy broadly applicable for the species-specific control of any pest or vector species with an XY sex-determination system by targeting sequences exclusive to the female sex chromosome. PMID:27484623

  20. Past experiences of adults with disorders of sex development.

    PubMed

    Audí, Laura

    2014-01-01

    When a human being born with any disorder/difference of sex development (DSD) reaches adulthood, the experience lived may be quite varied, depending partly on the age at diagnosis, the underlying cause, physical and health involvement, family circle, health system care received, societal culture and psychological ability to face the process, etc. As affected persons may suffer not only from diverse types of physical differences, but also difficulties in adapting their lives to the most common social mores, international consensus has long advocated a pluridisciplinary care involving different medical specialities. Although healthcare systems have progressively improved, the physical and psychological experiences of these adults may often have been stressful or traumatic, partly due to the 'rarity or low frequency' of their condition, and also to the fact that the person's sexual life is involved. The creation of support groups by affected individuals and their activities have proved extremely rewarding by improving individual well-being and pushing healthcare systems towards higher standards. In this chapter, we present the work of a patient support group in Spain (objectives, activities and opinions) and reflect present views and past experiences of a number of its adult members. PMID:25247651

  1. Effects of temperature and host stage on the parasitization rate and offspring sex ratio of Aenasius bambawalei Hayat in Phenacoccus solenopsis Tinsley

    PubMed Central

    Zhang, Juan; Xia, Tianfeng

    2016-01-01

    Temperature and host stage are important factors that determine the successful development of parasitoids. Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae) is a primary parasitoid of the newly invasive mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). The effects of temperature on the parasitic characteristics of A. bambawalei have seldom been investigated. In the study, we explored the effects of temperature, exposure time, and host stage on the parasitization rate and offspring sex ratio (female to male) of A. bambawalei under laboratory conditions. The laboratory results showed that the successful parasitization rate of A. bambawalei increased with higher temperatures and older host stages. When the parasitoids were exposed to 36 °C for 24 h, the parasitization rate of female adults (52%) was nearly two times that of 3rd instar nymphs. Additionally, heat stress duration and host stage resulted in an increase in the offspring sex ratio of A. bambawalei. When A. bambawalei was exposed to 36 °C for 24 h, the offspring sex ratio increased dramatically to 81.78% compared with those exposed for 12 h, and it increased to 45.34% compared with those exposed for 16 h. The offspring sex ratio was clearly higher when the host stage was an adult female mealybug Our findings provide important guidance for the mass rearing and field releases of A. bambawalei for the management of P. solenopsis in the future. PMID:26788437

  2. Quantifying the relative risk of sex offenders: risk ratios for static-99R.

    PubMed

    Hanson, R Karl; Babchishin, Kelly M; Helmus, Leslie; Thornton, David

    2013-10-01

    Given the widespread use of empirical actuarial risk tools in corrections and forensic mental health, it is important that evaluators and decision makers understand how scores relate to recidivism risk. In the current study, we found strong evidence for a relative risk interpretation of Static-99R scores using 8 samples from Canada, United Kingdom, and Western Europe (N = 4,037 sex offenders). Each increase in Static-99R score was associated with a stable and consistent increase in relative risk (as measured by an odds ratio or hazard ratio of approximately 1.4). Hazard ratios from Cox regression were used to calculate risk ratios that can be reported for Static-99R. We recommend that evaluators consider risk ratios as a useful, nonarbitrary metric for quantifying and communicating risk information. To avoid misinterpretation, however, risk ratios should be presented with recidivism base rates. PMID:23264543

  3. Logging Affects Fledgling Sex Ratios and Baseline Corticosterone in a Forest Songbird

    PubMed Central

    Leshyk, Rhiannon; Nol, Erica; Burke, Dawn M.; Burness, Gary

    2012-01-01

    Silviculture (logging) creates a disturbance to forested environments. The degree to which forests are modified depends on the logging prescription and forest stand characteristics. In this study we compared the effects of two methods of group-selection (“moderate” and “heavy”) silviculture (GSS) and undisturbed reference stands on stress and offspring sex ratios of a forest interior species, the Ovenbird (Seiurus aurocapilla), in Algonquin Provincial Park, Canada. Blood samples were taken from nestlings for corticosterone and molecular sexing. We found that logging creates a disturbance that is stressful for nestling Ovenbirds, as illustrated by elevated baseline corticosterone in cut sites. Ovenbirds nesting in undisturbed reference forest produce fewer male offspring per brood (proportion male = 30%) while logging with progressively greater forest disturbance, shifted the offspring sex ratio towards males (proportion male: moderate = 50%, heavy = 70%). If Ovenbirds in undisturbed forests usually produce female-biased broods, then the production of males as a result of logging may disrupt population viability. We recommend a broad examination of nestling sex ratios in response to anthropogenic disturbance to determine the generality of our findings. PMID:22432000

  4. Transgenerational plasticity mitigates the impact of global warming to offspring sex ratios.

    PubMed

    Donelson, Jennifer M; Munday, Philip L

    2015-08-01

    Global warming poses a threat to organisms with temperature-dependent sex determination because it can affect operational sex ratios. Using a multigenerational experiment with a marine fish, we provide the first evidence that parents developing from early life at elevated temperatures can adjust their offspring gender through nongenetic and nonbehavioural means. However, this adjustment was not possible when parents reproduced, but did not develop, at elevated temperatures. Complete restoration of the offspring sex ratio occurred when parents developed at 1.5 °C above the present-day average temperature for one generation. However, only partial improvement in the sex ratio occurred at 3.0 °C above average conditions, even after two generations, suggesting a limitation to transgenerational plasticity when developmental temperature is substantially increased. This study highlights the potential for transgenerational plasticity to ameliorate some impacts of climate change and that development from early life may be essential for expression of transgenerational plasticity in some traits. PMID:25820432

  5. Factors modifying valproate plasma level/dose ratio: age, sex, dose and plasma level.

    PubMed

    Sánchez, A; Durán, J A; Abadín, J A

    1989-09-01

    Valproate plasma level/dose (L/D) ratios obtained from 155 outpatients under long-term monotherapeutic regimen have been studied. Analytical data were obtained by enzymatic immunoassay (EMIT) from paired samples taken before the morning drug dosage. L/D ratios were increased with age and plasma level and decreased with dose. There were no sex differences in L/D in the different age, dose and concentration groups. L/D ratios were higher than those found by other researchers in our country. PMID:2511386

  6. Effects of diets supplemented by fish oil on sex ratio of pups in bitch.

    PubMed

    Gharagozlou, Faramarz; Youssefi, Reza; Akbarinejad, Vahid

    2016-01-01

    The present study was conducted to evaluate the effect of fish oil supplementation prior to mating on secondary sex ratio of pups (the proportion of males at birth) in bitches. Sixty five bitches (German Shepherd, n = 35; Husky, n = 30) were enrolled in the study. Bitches (140-150 days post-estrus) were given 2% per dry matter intake palm oil and fish oil in the control (n = 33) and treatment (n = 32) groups, respectively. To induce estrus, bitches were received equine chorionic gonadotropin (eCG) administration (50 IU kg(-1)) 30 days after nutritional supplementation followed by human chorionic gonadotropin (hCG) administration (500 IU per dog) seven days later. Bitches were introduced to dogs of the same breed after hCG administration. The weight of bitches was increased over time (p < 0.05), but their weight change was not different between two groups (p > 0.05). The mating rate, pregnancy rate and litter size were not influenced by treatment and breed. Secondary sex ratio was higher in the treatment (105/164; 64.00%) than in the control (68/147; 46.30%) group (p < 0.05; adjusted odds ratio = 2.068). Moreover, secondary sex ratio was higher in Husky bitches (88/141; 62.40%) compared to German Shepherd (85/170; 50.00%; p < 0.05; adjusted odds ratio = 1.661). In conclusion, the present study showed that inclusion of fish oil in the diet of bitches prior to mating could increase the proportion of male pups at birth. In addition, it appears that there might be variation among dog breeds with regard to the sex ratio of offspring. PMID:27482354

  7. Effects of diets supplemented by fish oil on sex ratio of pups in bitch

    PubMed Central

    Gharagozlou, Faramarz; Youssefi, Reza; Akbarinejad, Vahid

    2016-01-01

    The present study was conducted to evaluate the effect of fish oil supplementation prior to mating on secondary sex ratio of pups (the proportion of males at birth) in bitches. Sixty five bitches (German Shepherd, n = 35; Husky, n = 30) were enrolled in the study. Bitches (140-150 days post-estrus) were given 2% per dry matter intake palm oil and fish oil in the control (n = 33) and treatment (n = 32) groups, respectively. To induce estrus, bitches were received equine chorionic gonadotropin (eCG) administration (50 IU kg-1) 30 days after nutritional supplementation followed by human chorionic gonadotropin (hCG) administration (500 IU per dog) seven days later. Bitches were introduced to dogs of the same breed after hCG administration. The weight of bitches was increased over time (p < 0.05), but their weight change was not different between two groups (p > 0.05). The mating rate, pregnancy rate and litter size were not influenced by treatment and breed. Secondary sex ratio was higher in the treatment (105/164; 64.00%) than in the control (68/147; 46.30%) group (p < 0.05; adjusted odds ratio = 2.068). Moreover, secondary sex ratio was higher in Husky bitches (88/141; 62.40%) compared to German Shepherd (85/170; 50.00%; p < 0.05; adjusted odds ratio = 1.661). In conclusion, the present study showed that inclusion of fish oil in the diet of bitches prior to mating could increase the proportion of male pups at birth. In addition, it appears that there might be variation among dog breeds with regard to the sex ratio of offspring. PMID:27482354

  8. Population sex-ratio affecting behavior and physiology of overwintering bank voles (Myodes glareolus).

    PubMed

    Sipari, Saana; Haapakoski, Marko; Klemme, Ines; Palme, Rupert; Sundell, Janne; Ylönen, Hannu

    2016-05-15

    Many boreal rodents are territorial during the breeding season but during winter become social and aggregate for more energy efficient thermoregulation. Communal winter nesting and social interactions are considered to play an important role for the winter survival of these species, yet the topic is relatively little explored. Females are suggested to be the initiators of winter aggregations and sometimes reported to survive better than males. This could be due to the higher social tolerance observed in overwintering females than males. Hormonal status could also affect winter behavior and survival. For instance, chronic stress can have a negative effect on survival, whereas high gonadal hormone levels, such as testosterone, often induce aggressive behavior. To test if the winter survival of females in a boreal rodent is better than that of males, and to assess the role of females in the winter aggregations, we generated bank vole (Myodes glareolus) populations of three different sex ratios (male-biased, female-biased and even density) under semi-natural conditions. We monitored survival, spatial behavior and hormonal status (stress and testosterone) during two winter months. We observed no significant differences in survival between the sexes or among populations with differing sex-ratios. The degree of movement area overlap was used as an indicator of social tolerance and potential communal nesting. Individuals in male biased populations showed a tendency to be solitary, whereas in female biased populations there was an indication of winter aggregation. Females living in male-biased populations had higher stress levels than the females from the other populations. The female-biased sex-ratio induced winter breeding and elevated testosterone levels in males. Thus, our results suggest that the sex-ratio of the overwintering population can lead to divergent overwintering strategies in bank voles. PMID:26976741

  9. Between-year variation in population sex ratio increases with complexity of the breeding system in Hymenoptera.

    PubMed

    Kümmerli, Rolf; Keller, Laurent

    2011-06-01

    While adaptive adjustment of sex ratio in the function of colony kin structure and food availability commonly occurs in social Hymenoptera, long-term studies have revealed substantial unexplained between-year variation in sex ratio at the population level. In order to identify factors that contribute to increased between-year variation in population sex ratio, we conducted a comparative analysis across 47 Hymenoptera species differing in their breeding system. We found that between-year variation in population sex ratio steadily increased as one moved from solitary species, to primitively eusocial species, to single-queen eusocial species, to multiple-queen eusocial species. Specifically, between-year variation in population sex ratio was low (6.6% of total possible variation) in solitary species, which is consistent with the view that in solitary species, sex ratio can vary only in response to fluctuations in ecological factors such as food availability. In contrast, we found significantly higher (19.5%) between-year variation in population sex ratio in multiple-queen eusocial species, which supports the view that in these species, sex ratio can also fluctuate in response to temporal changes in social factors such as queen number and queen-worker control over sex ratio, as well as factors influencing caste determination. The simultaneous adjustment of sex ratio in response to temporal fluctuations in ecological and social factors seems to preclude the existence of a single sex ratio optimum. The absence of such an optimum may reflect an additional cost associated with the evolution of complex breeding systems in Hymenoptera societies. PMID:21597259

  10. Unexpected consequences of a drier world: evidence that delay in late summer rains biases the population sex ratio of an insect.

    PubMed

    Bonal, Raul; Hernández, Marisa; Espelta, Josep M; Muñoz, Alberto; Aparicio, José M

    2015-09-01

    The complexity of animal life histories makes it difficult to predict the consequences of climate change on their populations. In this paper, we show, for the first time, that longer summer drought episodes, such as those predicted for the dry Mediterranean region under climate change, may bias insect population sex ratio. Many Mediterranean organisms, like the weevil Curculio elephas, become active again after summer drought. This insect depends on late summer rainfall to soften the soil and allow adult emergence from their underground refuges. We found that, as in many protandric species, more C. elephas females emerged later in the season. Male emergence timing was on average earlier and also more dependent on the beginning of late summer rainfall. When these rains were delayed, the observed weevil sex ratio was biased towards females. So far, the effects of global warming on animal sex ratios has been reported for temperature-dependent sex determination in reptiles. Our results show that rainfall timing can also bias the sex ratio in an insect, and highlight the need for keeping a phenological perspective to predict the consequences of climate change. We must consider not just the magnitude of the predicted changes in temperature and rainfall but also the effects of their timing. PMID:26473046

  11. Androgen receptor blockade using flutamide skewed sex ratio of litters in mice.

    PubMed

    Gharagozlou, Faramarz; Youssefi, Reza; Vojgani, Mehdi; Akbarinejad, Vahid; Rafiee, Ghazaleh

    2016-01-01

    Maternal testosterone has been indicated to affect sex ratio of offspring. The present study was conducted to elucidate the role of androgen receptor in this regard by blockade of androgen receptor using flutamide in female mice. Mice were randomly assigned to two experimental groups. Mice in the control (n = 20) and treatment (n = 20) groups received 8 IU equine chorionic gonadotropin (eCG) followed by human chorionic gonadotropin (hCG) injection (8 IU) 47 hr later. In addition, mice in the control and treatment groups received four injections of ethanol-saline vehicle and flutamide solution (2.50 mg), respectively, started from 1 hr before eCG injection until hCG injection at 12-hr intervals. Conception rate was not different between the treatment (18/20: 90.00%) and control (19/20: 95.00%) groups (p > 0.05). Litter size was higher in the treatment (8.22 ± 0.26) than control (7.21 ± 0.28) group (p < 0.05). Male sex ratio was lower in the flutamide-treated mice (67/148: 45.30%) as compared with the untreated ones (80/137: 58.40%; odds ratio = 1.69; p < 0.05). In conclusion, the results showed that androgen receptor blockade could skew sex ratio of offspring toward females implying that the effect of testosterone on sex ratio might be through binding to androgen receptor. In addition, the blockade of androgen receptor using flutamide appeared to enhance litter size. PMID:27482363

  12. Androgen receptor blockade using flutamide skewed sex ratio of litters in mice

    PubMed Central

    Gharagozlou, Faramarz; Youssefi, Reza; Vojgani, Mehdi; Akbarinejad, Vahid; Rafiee, Ghazaleh

    2016-01-01

    Maternal testosterone has been indicated to affect sex ratio of offspring. The present study was conducted to elucidate the role of androgen receptor in this regard by blockade of androgen receptor using flutamide in female mice. Mice were randomly assigned to two experimental groups. Mice in the control (n = 20) and treatment (n = 20) groups received 8 IU equine chorionic gonadotropin (eCG) followed by human chorionic gonadotropin (hCG) injection (8 IU) 47 hr later. In addition, mice in the control and treatment groups received four injections of ethanol-saline vehicle and flutamide solution (2.50 mg), respectively, started from 1 hr before eCG injection until hCG injection at 12-hr intervals. Conception rate was not different between the treatment (18/20: 90.00%) and control (19/20: 95.00%) groups (p > 0.05). Litter size was higher in the treatment (8.22 ± 0.26) than control (7.21 ± 0.28) group (p < 0.05). Male sex ratio was lower in the flutamide-treated mice (67/148: 45.30%) as compared with the untreated ones (80/137: 58.40%; odds ratio = 1.69; p < 0.05). In conclusion, the results showed that androgen receptor blockade could skew sex ratio of offspring toward females implying that the effect of testosterone on sex ratio might be through binding to androgen receptor. In addition, the blockade of androgen receptor using flutamide appeared to enhance litter size. PMID:27482363

  13. Predicted sex ratio of juvenile Hawksbill Seaturtles inhabiting Buck Island Reef national monument, U.S. Virgin Islands

    USGS Publications Warehouse

    Geis, A.; Wibbels, T.; Phillips, B.; Hillis-Starr, Z.; Meylan, A.; Meylan, P.; Diez, C.; Van Dam, R.

    2003-01-01

    Hawksbill Seaturtles have temperature-dependent sex determination. As such, the resulting sex ratios are of conservational and ecological significance. Buck Island Reef is an interesting location for sex ratio studies since it represents a natural and unexploited foraging ground for hawksbills in the Caribbean. To examine sex ratios, blood samples were obtained from juvenile Hawksbill Seaturtles captured on Buck Island Reef over a four-year period. We used a radioimmunoassay to determine testosterone levels in those samples and compared those values to testosterone levels of juvenile hawksbills from the Caribbean whose sex has been verified by laparoscopy. The results of this study reveal a significantly female-biased sex ratio (approximately 80% female) occurs in this juvenile aggregation inhabiting Buck Island Reef.

  14. Sex-specific associations between birth weight and adult primary liver cancer in a large cohort of Danish children.

    PubMed

    Zimmermann, Esther; Berentzen, Tina L; Gamborg, Michael; Sørensen, Thorkild I A; Baker, Jennifer L

    2016-03-15

    Whether the prenatal period is critical for the development of adult primary liver cancer (PLC) is sparsely investigated. Recently, attention has been drawn to potential sex-differences in the early origins of adult disease. The association between birth weight and adult PLC, separately in men and women was investigated, using a large cohort of 217,227 children (51% boys), born from 1936 to 1980, from the Copenhagen School Health Records Register, and followed them until 2010 in national registers. Hazard ratios (95% confidence intervals) of PLC (30 years or older) were estimated by Cox regression models stratified by birth cohort. During 5.1 million person-years of follow-up, 185 men and 65 women developed PLC. Sex modified the association between birth weight and adult PLC (p values for interaction = 0.0005). Compared with a sex-specific reference group of birth weights between 3.25 and 3.75 kg, men with birth weights between 2.00 and 3.25 kg and 3.75-5.50 kg, had HRs of 1.48 (1.06-2.05) and 0.85 (0.56-1.28), respectively. Among women the corresponding HRs were 1.71 (0.90-3.29) and 3.43 (1.73-6.82). Associations were similar for hepatocellular carcinoma only, across year of birth, and after accounting for diagnoses of alcohol-related disorders, viral hepatitis and biliary cirrhosis. Prenatal exposures influenced the risk of adult PLC, and the effects at the high birth weight levels appeared to be sex-specific. These findings underscore the importance of considering sex-specific mechanisms in the early origins of adult PLC. PMID:26506514

  15. Sexual history disclosure polygraph outcomes: do juvenile and adult sex offenders differ?

    PubMed

    Jensen, Todd M; Shafer, Kevin; Roby, C Y; Roby, Jini L

    2015-03-01

    Despite the empirical and theoretical chasm between the opponents and proponents of polygraphy, its use is prominent among sex offender agencies in the United States. However, current research on polygraph examination outcomes among juvenile sex offenders, along with potential differences from their adult counterparts, is scarce and outdated. In the present study, we assess the difference between juvenile and adult sex offenders in terms of the propensity for passing a sexual history disclosure polygraph examination. A sample of 324 sex offenders (86 juveniles and 238 adults) who engaged in a sexual history disclosure polygraph examination as part of their treatment in an Intermountain West sex offender treatment agency was used for the analysis. Results from preliminary and logistic regression analyses indicate that juvenile and adult offenders do not significantly differ in the likelihood of passing a sexual history disclosure polygraph examination. Implications and limitations are discussed. PMID:25049032

  16. Sex hormones and adult hippocampal neurogenesis: Regulation, implications, and potential mechanisms.

    PubMed

    Mahmoud, Rand; Wainwright, Steven R; Galea, Liisa A M

    2016-04-01

    Neurogenesis within the adult hippocampus is modulated by endogenous and exogenous factors. Here, we review the role of sex hormones in the regulation of adult hippocampal neurogenesis in males and females. The review is framed around the potential functional implications of sex hormone regulation of adult hippocampal neurogenesis, with a focus on cognitive function and mood regulation, which may be related to sex differences in incidence and severity of dementia and depression. We present findings from preclinical studies of endogenous fluctuations in sex hormones relating to reproductive function and ageing, and from studies of exogenous hormone manipulations. In addition, we discuss the modulating roles of sex, age, and reproductive history on the relationship between sex hormones and neurogenesis. Because sex hormones have diverse targets in the central nervous system, we overview potential mechanisms through which sex hormones may influence hippocampal neurogenesis. Lastly, we advocate for a more systematic consideration of sex and sex hormones in studying the functional implications of adult hippocampal neurogenesis. PMID:26988999

  17. Thermal fluctuation within nests and predicted sex ratio of Morelet's Crocodile.

    PubMed

    Escobedo-Galván, Armando H; López-Luna, Marco A; Cupul-Magaña, Fabio G

    2016-05-01

    Understanding the interplay between thermal variations and sex ratio in reptiles with temperature-dependent sex determination is the first step for developing long-term conservation strategies. In case of crocodilians, the information is fragmentary and insufficient for establishing a general framework to consider how thermal fluctuation influence sex determination under natural conditions. The main goal of this study was to analyze thermal variation in nests of Crocodylus moreletii and to discuss the potential implications for predicting offspring sex ratio. The study was carried out at the Centro de Estudios Tecnológicos del Mar N° 2 and at the Sistemas Productivos Cocodrilo, Campeche, Mexico. Data was collected in the nesting season of Morelet's Crocodiles during three consecutive seasons (2007-2009). Thermal fluctuations for multiple areas of the nest chamber were registered by data loggers. We calculate the constant temperature equivalent based on thermal profiles among nests to assess whether there are differences between the nest temperature and its equivalent to constant temperature. We observed that mean nest temperature was only different among nests, while daily thermal fluctuations vary depending on the depth position within the nest chamber, years and nests. The constant temperature equivalent was different among and within nests, but not among survey years. We observed differences between constant temperature equivalent and mean nest temperature both at the top and in the middle of the nest cavities, but were not significantly different at the bottom of nest cavities. Our results enable examine and discuss the relevance of daily thermal fluctuations to predict sex ratio of the Morelet's Crocodile. PMID:27157330

  18. Parental thermal environment alters offspring sex ratio and fitness in an oviparous lizard.

    PubMed

    Schwanz, Lisa E

    2016-08-01

    The environment experienced by parents can impact the phenotype of their offspring (parental effects), a critical component of organismal ecology and evolution in variable or changing environments. Although temperature is a central feature of the environment for ectotherms, its role in parental effects has been little explored until recently. Here, parental basking opportunity was manipulated in an oviparous lizard with temperature-dependent sex determination, the jacky dragon (Amphibolurus muricatus). Eggs were incubated at a temperature that typically produces a 50:50 sex ratio, and hatchlings were reared in a standard thermal environment. Offspring of parents in short bask conditions appeared to have better fitness outcomes in captive conditions than those of parents in long bask conditions - they had greater growth and survival as a function of their mass. In addition, the sex of offspring (male or female) depended on the interaction between parental treatment and egg mass, and treatment impacted whether sons or daughters grew larger in their first season. The interactive effects of treatment on offspring sex and growth are consistent with adaptive explanations for the existence of temperature-dependent sex determination in this species. Moreover, the greater performance recorded in short bask offspring may represent an anticipatory parental effect to aid offspring in predicted conditions of restricted thermal opportunity. Together, these responses constitute a crucial component of the population response to spatial or temporal variation in temperature. PMID:27229475

  19. Effects of thyroid endocrine manipulation on sex-related gene expression and population sex ratios in Zebrafish.

    PubMed

    Sharma, Prakash; Tang, Song; Mayer, Gregory D; Patiño, Reynaldo

    2016-09-01

    Thyroid hormone reportedly induces masculinization of genetic females and goitrogen treatment delays testicular differentiation (ovary-to-testis transformation) in genetic males of Zebrafish. This study explored potential molecular mechanisms of these phenomena. Zebrafish were treated with thyroxine (T4, 2nM), goitrogen [methimazole (MZ), 0.15mM], MZ (0.15mM) and T4 (2nM) (rescue treatment), or reconstituted water (control) from 3 to 33days postfertilization (dpf) and maintained in control water until 45dpf. Whole fish were collected during early (25dpf) and late (45dpf) testicular differentiation for transcript abundance analysis of selected male (dmrt1, amh, ar) and female (cyp19a1a, esr1, esr2a, esr2b) sex-related genes by quantitative RT-PCR, and fold-changes relative to control values were determined. Additional fish were sampled at 45dpf for histological assessment of gonadal sex. The T4 and rescue treatments caused male-biased populations, and T4 alone induced precocious puberty in ∼50% of males. Male-biased sex ratios were accompanied by increased expression of amh and ar and reduced expression of cyp19a1a, esr1, esr2a, and esr2b at 25 and 45dpf and, unexpectedly, reduced expression of dmrt1 at 45dpf. Goitrogen exposure increased the proportion of individuals with ovaries (per previous studies interpreted as delay in testicular differentiation of genetic males), and at 25 and 45dpf reduced the expression of amh and ar and increased the expression of esr1 (only at 25dpf), esr2a, and esr2b. Notably, cyp19a1a transcript was reduced but via non-thyroidal pathways (not restored by rescue treatment). In conclusion, the masculinizing activity of T4 at the population level may be due to its ability to inhibit female and stimulate male sex-related genes in larvae, while the inability of MZ to induce cyp19a1a, which is necessary for ovarian differentiation, may explain why its "feminizing" activity on gonadal sex is not permanent. PMID:27255368

  20. Effects of thyroid endocrine manipulation on sex-related gene expression and population sex ratios in Zebrafish

    USGS Publications Warehouse

    Sharma, Prakash; Tang, Song; Mayer, Gregory D.; Patino, Reynaldo

    2016-01-01

    Thyroid hormone reportedly induces masculinization of genetic females and goitrogen treatment delays testicular differentiation (ovary-to-testis transformation) in genetic males of Zebrafish. This study explored potential molecular mechanisms of these phenomena. Zebrafish were treated with thyroxine (T4, 2 nM), goitrogen [methimazole (MZ), 0.15 mM], MZ (0.15 mM) and T4 (2 nM) (rescue treatment), or reconstituted water (control) from 3 to 33 days postfertilization (dpf) and maintained in control water until 45 dpf. Whole fish were collected during early (25 dpf) and late (45 dpf) testicular differentiation for transcript abundance analysis of selected male (dmrt1, amh, ar) and female (cyp19a1a, esr1, esr2a, esr2b) sex-related genes by quantitative RT-PCR, and fold-changes relative to control values were determined. Additional fish were sampled at 45 dpf for histological assessment of gonadal sex. The T4 and rescue treatments caused male-biased populations, and T4 alone induced precocious puberty in ∼50% of males. Male-biased sex ratios were accompanied by increased expression of amh and ar and reduced expression of cyp19a1a, esr1, esr2a, and esr2b at 25 and 45 dpf and, unexpectedly, reduced expression of dmrt1 at 45 dpf. Goitrogen exposure increased the proportion of individuals with ovaries (per previous studies interpreted as delay in testicular differentiation of genetic males), and at 25 and 45 dpf reduced the expression of amh and ar and increased the expression of esr1 (only at 25 dpf), esr2a, and esr2b. Notably, cyp19a1a transcript was reduced but via non-thyroidal pathways (not restored by rescue treatment). In conclusion, the masculinizing activity of T4 at the population level may be due to its ability to inhibit female and stimulate male sex-related genes in larvae, while the inability of MZ to induce cyp19a1a, which is necessary for ovarian differentiation, may explain why its “feminizing” activity on gonadal

  1. Same-Sex Behavior and Health Indicators of Sexually Experienced Filipino Young Adults

    PubMed Central

    Cheng, Chia-Hsin Emily; Perez, Tita Lorna; Cochran, Susan D.

    2015-01-01

    The Philippines is one of seven countries in which HIV incidence has recently increased—much of this increase has been among men who have sex with men. Despite this trend, knowledge on sexuality and same-sex behaviors in the Philippines is limited. This study examines same-sex behavior, sexual outcomes, substance use, and psychological distress among young adults participating in the 2005 Cebu Longitudinal Health and Nutrition Survey (CLHNS). We use gender-stratified, multivariate models to compare young adults who reported same-sex behaviors and those who did not. Among a cohort of 1,912 Filipino young adults (ages 20–22), 58.2% were sexually experienced and 15.1% of them reported same-sex sexual contacts or romantic relationships. Compared to females, more males reported same-sex sexual contact (19.4 vs. 2.3 %) or same-sex romantic relationships (9.2 vs. 4.1 %). Young adults reporting same-sex behavior had higher odds of smoking, drug use, perceived stress, and more sexual partners as compared to their peers. Males who reported same-sex behavior initiated sex earlier than those males who did not report same-sex behaviors. There were no significant differences in depressive distress. Earlier sexual initiation and higher levels of substance use among Filipino young adults engaging in same-sex behavior highlight the need to address unique health issues within this population. Mixed findings for depressive distress and perceived stress indicate that further investigation is needed to explore the potential impacts of same-sex status on mental health outcomes, particularly in lower- and middle-income countries such as the Philippines. PMID:25416159

  2. Same-Sex Behavior and Health Indicators of Sexually Experienced Filipino Young Adults.

    PubMed

    Cheng, Chia-Hsin Emily; Gipson, Jessica D; Perez, Tita Lorna; Cochran, Susan D

    2016-08-01

    The Philippines is one of seven countries in which HIV incidence has recently increased-much of this increase has been among men who have sex with men. Despite this trend, knowledge on sexuality and same-sex behaviors in the Philippines is limited. This study examines same-sex behavior, sexual outcomes, substance use, and psychological distress among young adults participating in the 2005 Cebu Longitudinal Health and Nutrition Survey (CLHNS). We use gender-stratified, multivariate models to compare young adults who reported same-sex behaviors and those who did not. Among a cohort of 1,912 Filipino young adults (ages 20-22), 58.2 % were sexually experienced and 15.1 % of them reported same-sex sexual contacts or romantic relationships. Compared to females, more males reported same-sex sexual contact (19.4 vs. 2.3 %) or same-sex romantic relationships (9.2 vs. 4.1 %). Young adults reporting same-sex behavior had higher odds of smoking, drug use, perceived stress, and more sexual partners as compared to their peers. Males who reported same-sex behavior initiated sex earlier than those males who did not report same-sex behaviors. There were no significant differences in depressive distress. Earlier sexual initiation and higher levels of substance use among Filipino young adults engaging in same-sex behavior highlight the need to address unique health issues within this population. Mixed findings for depressive distress and perceived stress indicate that further investigation is needed to explore the potential impacts of same-sex status on mental health outcomes, particularly in lower- and middle-income countries such as the Philippines. PMID:25416159

  3. National and State-Specific Health Insurance Disparities for Adults in Same-Sex Relationships

    PubMed Central

    Blewett, Lynn A.

    2014-01-01

    Objectives. We examined national and state-specific disparities in health insurance coverage, specifically employer-sponsored insurance (ESI) coverage, for adults in same-sex relationships. Methods. We used data from the American Community Survey to identify adults (aged 25–64 years) in same-sex relationships (n = 31 947), married opposite-sex relationships (n = 3 060 711), and unmarried opposite-sex relationships (n = 259 147). We estimated multinomial logistic regression models and state-specific relative differences in ESI coverage with predictive margins. Results. Men and women in same-sex relationships were less likely to have ESI than were their married counterparts in opposite-sex relationships. We found ESI disparities among adults in same-sex relationships in every region, but we found the largest ESI gaps for men in the South and for women in the Midwest. ESI disparities were narrower in states that had extended legal same-sex marriage, civil unions, and broad domestic partnerships. Conclusions. Men and women in same-sex relationships experience disparities in health insurance coverage across the country, but residing in a state that recognizes legal same-sex marriage, civil unions, or broad domestic partnerships may improve access to ESI for same-sex spouses and domestic partners. PMID:24328616

  4. Mutually beneficial host exploitation and ultra-biased sex ratios in quasisocial parasitoids

    PubMed Central

    Tang, Xiuyun; Meng, Ling; Kapranas, Apostolos; Xu, Fuyuan; Hardy, Ian C.W.; Li, Baoping

    2014-01-01

    Selfish interests usually preclude resource sharing, but under some conditions collective actions enhance per capita gains. Such Allee effects underlay early explanations of social evolution but current understanding focusses on kin selection (inclusive fitness). We find an Allee effect that explains unusual quasisociality (cooperative brood care) among parasitoid wasps without invoking or precluding kin selection effects. In Sclerodermus harmandi, individual females produce most offspring when exploiting small hosts alone. However, larger hosts are more successfully exploited by larger groups of females, with the per-female benefits outweighing the costs of host sharing. Further, the extremely biased sex ratios (97% female) are better explained by mutually beneficial female–female interactions that increase the reproductive value of daughters (local resource enhancement), rather than by the usually invoked local mate competition between males. Thus, atypical quasisocial behaviour in a parasitoid wasp directly enhances reproductive success and selects for very extremely female-biased sex ratios. PMID:25216091

  5. Use of 35-mm color aerial photography to acquire mallard sex ratio data

    USGS Publications Warehouse

    Ferguson, E.L.; Jorde, D.G.; Sease, J.L.

    1981-01-01

    A conventional 35-mm camera equipped with an f2.8 135-mm lens and ASA 64 color film was used to acquire sex ratio data on mallards (Anas platyrhynchos) wintering in the Platte River Valley of south-central Nebraska. Prelight focusing for a distance of 30.5 metres and setting of shutter speed at 1/2000 of a second eliminated focusing and reduced image motion problems and resulted in high-resolution, large-scale aerial photography of small targets. This technique has broad application to the problem of determining sex ratios of various species of waterfowl concentrated on wintering and staging areas. The aerial photographic method was cheaper than the ground ocular method when costs were compared on a per-100 bird basis.

  6. Evolutionary ecology of human birth sex ratio under the compound influence of climate change, famine, economic crises and wars.

    PubMed

    Helle, Samuli; Helama, Samuli; Lertola, Kalle

    2009-11-01

    1. Human sex ratio at birth at the population level has been suggested to vary according to exogenous stressors such as wars, ambient temperature, ecological disasters and economic crises, but their relative effects on birth sex ratio have not been investigated. It also remains unclear whether such associations represent environmental forcing or adaptive parental response, as parents may produce the sex that has better survival prospects and fitness in a given environmental challenge. 2. We examined the simultaneous role of wars, famine, ambient temperature, economic development and total mortality rate on the annual variation of offspring birth sex ratio and whether this variation, in turn, was related to sex-specific infant mortality rate in Finland during 1865-2003. 3. Our findings show an increased excess of male births during the World War II and during warm years. Instead, economic development, famine, short-lasting Finnish civil war and total mortality rate were not related to birth sex ratio. Moreover, we found no association between annual birth sex ratio and sex-biased infant mortality rate among the concurrent cohort. 4. Our results propose that some exogenous challenges like ambient temperature and war can skew human birth sex ratio and that these deviations likely represent environmental forcing rather than adaptive parental response to such challenges. PMID:19719518

  7. [Long-term effects of dioxin on human health and sex ratio].

    PubMed

    Iguchi, T

    2000-12-01

    Extremely high dioxins exposure has been reported in 35 men dismantled an incinerator in Osaka, Japan. The average of the serum dioxin concentration in the workers was 680 pg, the maximum concentration was 5380 pg, these values were 200-300 times higher than normal healthy Japanese men(20-30 pg). The present article reviewed long-term effects of dioxins on human health and sex ratios after accidental dioxins exposure in Seveso, Italy, based on the recently published articles. PMID:11187745

  8. Observations on sex ratio and behavior of males in Xyleborinus saxesenii Ratzeburg (Scolytinae, Coleoptera)

    PubMed Central

    H.W. Biedermann, Peter

    2010-01-01

    Abstract Strongly female-biased sex ratios are typical for the fungalfeeding haplodiploid Xyleborini (Scolytinae, Coleoptera), and are a result of inbreeding and local mate competition (LMC). These ambrosia beetles are hardly ever found outside of trees, and thus male frequency and behavior have not been addressed in any empirical studies to date. In fact, for most species the males remain undescribed. Data on sex ratios and male behavior could, however, provide important insights into the Xyleborini’s mating system and the evolution of inbreeding and LMC in general. In this study, I used in vitro rearing methods to obtain the first observational data on sex ratio, male production, male and female dispersal, and mating behavior in a xyleborine ambrosia beetle. Females of Xyleborinus saxesenii Ratzeburg produced between 0 and 3 sons per brood, and the absence of males was relatively independent of the number of daughters to be fertilized and the maternal brood sex ratio. Both conformed to a strict LMC strategy with a relatively precise and constant number of males. If males were present they eclosed just before the first females dispersed, and stayed in the gallery until all female offspring had matured. They constantly wandered through the gallery system, presumably in search of unfertilized females, and attempted to mate with larvae, other males, and females of all ages. Copulations, however, only occurred with immature females. From galleries with males, nearly all females dispersed fertilized. Only a few left the natal gallery without being fertilized, and subsequently went on to produce large and solely male broods. If broods were male-less, dispersing females always failed to found new galleries. PMID:21594184

  9. Sex-ratio conflicts, kin selection, and the evolution of altruism

    PubMed Central

    Alonso, Wladimir J.; Schuck-Paim, Cynthia

    2002-01-01

    Kin-selection theory has thrived in the explanation of a wide variety of biological phenomena, chiefly the evolution of biological altruism as that found in sterile castes of eusocial insects. Much of the way in which it has been tested is based on the existence of conflicts over sex-ratio production within eusocial colonies. However, despite neatly showing eusocial colonies as arenas where selection at the gene level triggers the appearance of sophisticated disputes, these studies have only demonstrated the existence of genes that act by biasing sex ratios to promote their own spread. Here we argue that such genes depend on the social organization of the colonies where they are expressed, but that they are not, in any way, the precursors of these societies—the major implication being that unequivocal evidence that eusociality evolved through the action of kin-selected altruistic genes is still lacking. Additionally, we highlight the neglect of alternative theories on the explanation of both biological altruism and sex-ratio conflicts, and defend that the enthusiasm with the latter has, in some cases, led to its inappropriate use as a basis for the explanation of other biological characteristics of eusocial organisms, when accounts based on phylogenetic or physiological constraints are also available. PMID:11997461

  10. Inbreeding and selection on sex ratio in the bark beetle Xylosandrus germanus

    PubMed Central

    2011-01-01

    Background Local Mate Competition (LMC) theory predicts a female should produce a more female-biased sex ratio if her sons compete with each other for mates. Because it provides quantitative predictions that can be experimentally tested, LMC is a textbook example of the predictive power of evolutionary theory. A limitation of many earlier studies in the field is that the population structure and mating system of the studied species are often estimated only indirectly. Here we use microsatellites to characterize the levels of inbreeding of the bark beetle Xylosandrus germanus, a species where the level of LMC is expected to be high. Results For three populations studied, genetic variation for our genetic markers was very low, indicative of an extremely high level of inbreeding (FIS = 0.88). There was also strong linkage disequilibrium between microsatellite loci and a very strong genetic differentiation between populations. The data suggest that matings among non-siblings are very rare (3%), although sex ratios from X. germanus in both the field and the laboratory have suggested more matings between non-sibs, and so less intense LMC. Conclusions Our results confirm that caution is needed when inferring mating systems from sex ratio data, especially when a lack of biological detail means the use of overly simple forms of the model of interest. PMID:22166098

  11. Parrotfish sex ratios recover rapidly in Bermuda following a fishing ban

    NASA Astrophysics Data System (ADS)

    O'Farrell, Shay; Luckhurst, Brian E.; Box, Stephen J.; Mumby, Peter J.

    2016-06-01

    Parrotfishes are an ecologically and commercially important teleost group whose grazing contributes to maintaining coral-dominated states on hermatypic reefs. However, overfishing has skewed sex ratios of Atlantic parrotfishes because fishing has disproportionate impacts on larger individuals, and males are generally larger than females. Whether protection from fishing may allow sex ratios to return to equilibrium is unknown, as fishing can induce irreversible ecological and/or evolutionary shifts. Bermuda banned trap fishing in 1990, creating a unique opportunity to analyse long-term responses of Atlantic parrotfishes to release from fishing. We found that sex ratios of four common parrotfishes were initially skewed, with male proportions ranging from 0.04 to 0.18. However, male proportions rebounded within 3-4 yr, equilibrating at values ranging from 0.36 to 0.54, similar to those reported at unfished sites in the region. Our results are encouraging for regional efforts to recover lost grazing function by restoring overfished herbivore populations.

  12. Sex Ratio Meiotic Drive as a Plausible Evolutionary Mechanism for Hybrid Male Sterility

    PubMed Central

    Zhang, Linbin; Xiao, Hailian; Tao, Yun

    2015-01-01

    Biological diversity on Earth depends on the multiplication of species or speciation, which is the evolution of reproductive isolation such as hybrid sterility between two new species. An unsolved puzzle is the exact mechanism(s) that causes two genomes to diverge from their common ancestor so that some divergent genes no longer function properly in the hybrids. Here we report genetic analyses of divergent genes controlling male fertility and sex ratio in two very young fruitfly species, Drosophila albomicans and D. nasuta. A majority of the genetic divergence for both traits is mapped to the same regions by quantitative trait loci mappings. With introgressions, six major loci are found to contribute to both traits. This genetic colocalization implicates that genes for hybrid male sterility have evolved primarily for controlling sex ratio. We propose that genetic conflicts over sex ratio may operate as a perpetual dynamo for genome divergence. This particular evolutionary mechanism may largely contribute to the rapid evolution of hybrid male sterility and the disproportionate enrichment of its underlying genes on the X chromosome – two patterns widely observed across animals. PMID:25822261

  13. Explaining the Rapid Increase in Nigeria's Sex Ratio at Birth: Factors and Implications.

    PubMed

    Kaba, Amadu J

    2015-06-01

    This paper examines the rapid increase in Nigeria's sex ratio at birth from 1.03 boys born for every 1 girl born in each year from 1996-2008 to 1.06 in each year from 2009-2014, second only to Tunisia in Africa at 1.07. The average sex ratio at birth in the world in 2014 was 1.07. In most Black African nations or Black majority nations, it is 1.03 or less. Among the factors presented for this development are: historical fluctuations of sex ratio at birth; geography and ethnicity; male preference/chasing a son; Age of parents; high death rates of male infants and males in general; and wealth/socioeconomic status. Among the potential implications are: young and poor men in Nigeria may not be able to find brides and form families due to a potential shortage of females; emigration of young and poor Nigerian men to West (Africa) and elsewhere to seek brides and form families; immigration of marriage age women from West (Africa) and around the world to Nigeria to seek husbands; and low contraceptive use and high fertility rates in Nigeria. PMID:26506655

  14. Learning About Sex: The Contemporary Guide for Young Adults.

    ERIC Educational Resources Information Center

    Kelly, Gary F.

    This book provides information about sex to help readers, particularly teenagers, clarify their needs and values relating to sex--to understand sex, to deal with their own sexuality constructively and responsibly, and to deal with the sexuality of others in ways that are considerate and helpful. It is designed for either classroom or individual…

  15. The influence of demography and local mating environment on sex ratios in a wind-pollinated dioecious plant

    PubMed Central

    Pickup, Melinda; Barrett, Spencer C H

    2013-01-01

    Negative frequency-dependent selection should result in equal sex ratios in large populations of dioecious flowering plants, but deviations from equality are commonly reported. A variety of ecological and genetic factors can explain biased sex ratios, although the mechanisms involved are not well understood. Most dioecious species are long-lived and/or clonal complicating efforts to identify stages during the life cycle when biases develop. We investigated the demographic correlates of sex-ratio variation in two chromosome races of Rumex hastatulus, an annual, wind-pollinated colonizer of open habitats from the southern USA. We examined sex ratios in 46 populations and evaluated the hypothesis that the proximity of males in the local mating environment, through its influence on gametophytic selection, is the primary cause of female-biased sex ratios. Female-biased sex ratios characterized most populations of R. hastatulus (mean sex ratio = 0.62), with significant female bias in 89% of populations. Large, high-density populations had the highest proportion of females, whereas smaller, low-density populations had sex ratios closer to equality. Progeny sex ratios were more female biased when males were in closer proximity to females, a result consistent with the gametophytic selection hypothesis. Our results suggest that interactions between demographic and genetic factors are probably the main cause of female-biased sex ratios in R. hastatulus. The annual life cycle of this species may limit the scope for selection against males and may account for the weaker degree of bias in comparison with perennial Rumex species. PMID:23532761

  16. Spatio-temporal variation in the incubation duration and sex ratio of hawksbill hatchlings: implication for future management.

    PubMed

    dei Marcovaldi, Maria A G; Santos, Armando J B; Santos, Alexsandro S; Soares, Luciano S; Lopez, Gustave G; Godfrey, Matthew H; López-Mendilaharsu, Milagros; Fuentes, Mariana M P B

    2014-08-01

    Climate change poses a unique threat to species with temperature dependent sex determination (TSD), such as marine turtles, where increases in temperature can result in extreme sex ratio biases. Knowledge of the primary sex ratio of populations with TSD is key for providing a baseline to inform management strategies and to accurately predict how future climate changes may affect turtle populations. However, there is a lack of robust data on offspring sex ratio at appropriate temporal and spatial scales to inform management decisions. To address this, we estimate the primary sex ratio of hawksbill hatchlings, Eretmochelys imbricata, from incubation duration of 5514 in situ nests from 10 nesting beaches from two regions in Brazil over the last 27 years. A strong female bias was estimated in all beaches, with 96% and 89% average female sex ratios produced in Bahia (BA) and Rio Grande do Norte (RN). Both inter-annual (BA, 88 to 99%; RN, 75 to 96% female) and inter-beach (BA, 92% to 97%; RN, 81% to 92% female) variability in mean offspring sex ratio was observed. These findings will guide management decisions in Brazil and provide further evidence of highly female-skew sex ratios in hawksbill turtles. PMID:25086976

  17. Maternal adjustment of the sex ratio in broods of the broad-horned flour beetle, Gnathocerus cornutus.

    PubMed

    Cruickshank, Tami; Wade, Michael J

    2012-07-01

    We report that females of the broad-horned flour beetle, Gnathocerus cornutus, can plastically adjust the sex ratio in their broods in response to environmental quality. Specifically, females reared in nutritionally poor environments produce broods that are 65% female, on average, with the degree of female-bias in some broods approaching 95%. In addition, females reared in nutritionally poor environments lay significantly more eggs than do females reared on standard medium, which produce broods with an even sex ratio. These effects of the mother's environment on size and sex ratio in broods are manifest even when oviposition occurs in the standard nutritional environment; indeed, the degree of female-bias increases with advancing female age despite the availability of nutritional resources to females at the time of egg laying. Our studies rule out sex-specific differences in viability early in larval development as the mechanism for the bias in sex-ratio of broods, since females reared in nutritionally poor environments have broods with hatchability and larval viability comparable to those of nonstressed females. Our studies also rule out an effect of the sire on the sex ratio in broods, since all male mates were reared on standard medium. We discuss our results in the context of theories for the evolution of plastic sex-ratios in the face of environmental deterioration and discuss how plasticity can resolve a long-standing question about the conditions underlying the evolution of biased sex ratios. PMID:22576817

  18. Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes.

    PubMed

    Douglas, T E; Strassmann, J E; Queller, D C

    2016-07-01

    Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types. PMID:27018644

  19. Sibling sex ratio and birth order in early-onset gender dysphoric adolescents.

    PubMed

    Schagen, Sebastian E E; Delemarre-van de Waal, Henriette A; Blanchard, Ray; Cohen-Kettenis, Peggy T

    2012-06-01

    Several sibship-related variables have been studied extensively in sexual orientation research, especially in men. Sibling sex ratio refers to the ratio of brothers to sisters in the aggregate sibships of a group of probands. Birth order refers to the probands' position (e.g., first-born, middle-born, last-born) within their sibships. Fraternal birth order refers to their position among male siblings only. Such research was extended in this study to a large group of early-onset gender dysphoric adolescents. The probands comprised 94 male-to-female and 95 female-to-male gender dysphoric adolescents. The overwhelming majority of these were homosexual or probably prehomosexual. The control group consisted of 875 boys and 914 girls from the TRAILS study. The sibling sex ratio of the gender dysphoric boys was very high (241 brothers per 100 sisters) compared with the expected ratio (106:100). The excess of brothers was more extreme among the probands' older siblings (300:100) than among their younger siblings (195:100). Between-groups comparisons showed that the gender dysphoric boys had significantly more older brothers, and significantly fewer older sisters and younger sisters, than did the control boys. In contrast, the only notable finding for the female groups was that the gender dysphoric girls had significantly fewer total siblings than did the control girls. The results for the male probands were consistent with prior speculations that a high fraternal birth order (i.e., an excess of older brothers) is found in all homosexual male groups, but an elevated sibling sex ratio (usually caused by an additional, smaller excess of younger brothers) is characteristic of gender dysphoric homosexual males. The mechanisms underlying these phenomena remain unknown. PMID:21674256

  20. Revisiting Geschwind's hypothesis on brain lateralisation: a functional MRI study of digit ratio (2D:4D) and sex interaction effects on spatial working memory.

    PubMed

    Kalmady, Sunil Vasu; Agarwal, Sri Mahavir; Shivakumar, Venkataram; Jose, Dania; Venkatasubramanian, Ganesan; Reddy, Y C Janardhan

    2013-01-01

    The Geschwind-Behan-Galaburda (GBG) hypothesis links cerebral lateralisation with prenatal testosterone exposure. Digit ratio measures in adults have been established as potential markers of foetal sex hormonal milieu. The aim of the study was to evaluate the sex-dependent interaction of digit ratio measures and cerebral lateralization as well as their neurohemodynamic correlates using functional MRI (fMRI). Digit ratio measures-ratio of index finger (2D) length to ring finger (4D) length (2D:4D) and difference between 2D:4D of two hands, i.e., right minus left (DR-L)-were calculated using high resolution digital images in 70 right-handed participants (42 men) based on reliable and valid method. fMRI was acquired during the performance of a spatial working memory task in a subset of 25 individuals (14 men), and analysed using Statistical Parametric Mapping 8 (SPM8) and the Laterality Index toolbox for SPM8. Men had significantly less bilateral 2D:4D than women. There was a significant negative correlation between right 2D:4D and 2-Back task accuracy (2BACC) in women. A significant sex-by-right 2D:4D interaction was observed in left parahippocampal gyrus activation. Additionally, sex-by-DR-L interaction was observed in left IPL activation. DR-L showed a significant positive correlation with the whole brain Laterality Index (LI), and LI, in turn, demonstrated a significant negative correlation with 2BACC. Our study observations suggest several novel sex-differential relationships between 2D:4D measures and fMRI activation during spatial working memory task performance. Given the pre-existing background data supporting digit ratio measures as putative indicator of prenatal sex hormonal milieu, our study findings add support to the Geschwind-Behan-Galaburda (GBG) hypothesis. PMID:23458090

  1. Sex ratio estimations of loggerhead sea turtle hatchlings by histological examination and nest temperatures at Fethiye beach, Turkey

    NASA Astrophysics Data System (ADS)

    Kaska, Yakup; Ilgaz, Çetin; Özdemir, Adem; Başkale, Eyüp; Türkozan, Oğuz; Baran, Ibrahim; Stachowitsch, Michael

    2006-07-01

    Hatchling sex ratios in the loggerhead turtle ( Caretta caretta) were estimated by placing electronic temperature recorders in 21 nests at Fethiye beach during 2000 2002. Over the seasons, the mean temperature in the middle third of the incubation period ranged from 26.7 to 32.1°C, and incubation periods ranged from 49 to 67 days. Based on the mean temperatures during the middle third of the incubation period, and on histologically sexed dead hatchlings, the sex ratios of hatchlings at Fethiye beach were roughly equal, i.e. 60 65% of the hatchlings were females. This contrasts with the highly female-skewed sex ratios in loggerhead turtles elsewhere; Fethiye has a relatively high proportion of male hatchlings. For endangered sea turtles, the knowledge of hatchling sex ratios at different beaches, coupled with appropriate conservation measures, can make an important contribution to their survival.

  2. Does breeding population trajectory and age of nesting females influence disparate nestling sex ratios in two populations of Cooper's hawks?

    PubMed

    Rosenfield, Robert N; Stout, William E; Giovanni, Matthew D; Levine, Noah H; Cava, Jenna A; Hardin, Madeline G; Haynes, Taylor G

    2015-09-01

    Offspring sex ratios at the termination of parental care should theoretically be skewed toward the less expensive sex, which in most avian species would be females, the smaller gender. Among birds, however, raptors offer an unusual dynamic because they exhibit reversed size dimorphism with females being larger than males. And thus theory would predict a preponderance of male offspring. Results for raptors and birds in general have been varied although population-level estimates of sex ratios in avian offspring are generally at unity. Adaptive adjustment of sex ratios in avian offspring is difficult to predict perhaps in part due to a lack of life-history details and short-term investigations that cannot account for precision or repeatability of sex ratios across time. We conducted a novel comparative study of sex ratios in nestling Cooper's hawks (Accipiter cooperii) in two study populations across breeding generations during 11 years in Wisconsin, 2001-2011. One breeding population recently colonized metropolitan Milwaukee and exhibited rapidly increasing population growth, while the ex-Milwaukee breeding population was stable. Following life-history trade-off theory and our prediction regarding this socially monogamous species in which reversed sexual size dimorphism is extreme, first-time breeding one-year-old, second-year females in both study populations produced a preponderance of the smaller and cheaper sex, males, whereas ASY (after-second-year), ≥2-year-old females in Milwaukee produced a nestling sex ratio near unity and predictably therefore a greater proportion of females compared to ASY females in ex-Milwaukee who produced a preponderance of males. Adjustment of sex ratios in both study populations occurred at conception. Life histories and selective pressures related to breeding population trajectory in two age cohorts of nesting female Cooper's hawk likely vary, and it is possible that these differences influenced the sex ratios we documented for

  3. Sex pheromone component ratios and mating isolation among three Lygus plant bug species of North America

    NASA Astrophysics Data System (ADS)

    Byers, John A.; Fefer, Daniela; Levi-Zada, Anat

    2013-12-01

    The plant bugs Lygus hesperus, Lygus lineolaris, and Lygus elisus (Hemiptera: Miridae) are major pests of many agricultural crops in North America. Previous studies suggested that females release a sex pheromone attractive to males. Other studies showed that males and females contain microgram amounts of ( E)-4-oxo-2-hexenal, hexyl butyrate, and ( E)-2-hexenyl butyrate that are emitted as a defense against predators. Using gas chromatography-mass spectrometry, we found that female L. lineolaris and L. elisus have a 4:10 ratio of hexyl butyrate to ( E)-2-hexenyl butyrate that is reversed from the 10:1 ratio in female L. hesperus (males of the three species have ~10:1 ratio). These reversed ratios among females of the species suggest a behavioral role. Because both sexes have nearly equal amounts of the major volatiles, females should release more to attract males. This expectation was supported because L. hesperus females released more hexyl butyrate (mean of 86 ng/h) during the night (1800-0700 hours) than did males (<1 ng/h). We used slow-rotating pairs of traps to test the attraction of species to blends of the volatiles with a subtractive method to detect synergism. Each species' major butyrate ester was released at 3 μg/h, the minor butyrate according to its ratio, and ( E)-4-oxo-2-hexenal at 2 μg/h. The resulting catches of only Lygus males suggest that ( E)-4-oxo-2-hexenal is an essential sex pheromone component for all three species, ( E)-2-hexenyl butyrate is essential for L. elisus and L. lineolaris, and hexyl butyrate is essential for L. hesperus. However, all three components are recognized by each species since ratios of the butyrate esters are critical for conspecific attraction and heterospecific avoidance by males and thus play a role in reproductive isolation among the three species. Because L. hesperus males and females are known to emit these major volatiles for repelling ant predators, our study links defensive allomones in Lygus bugs with an

  4. Sex pheromone component ratios and mating isolation among three Lygus plant bug species of North America.

    PubMed

    Byers, John A; Fefer, Daniela; Levi-Zada, Anat

    2013-12-01

    The plant bugs Lygus hesperus, Lygus lineolaris, and Lygus elisus (Hemiptera: Miridae) are major pests of many agricultural crops in North America. Previous studies suggested that females release a sex pheromone attractive to males. Other studies showed that males and females contain microgram amounts of (E)-4-oxo-2-hexenal, hexyl butyrate, and (E)-2-hexenyl butyrate that are emitted as a defense against predators. Using gas chromatography-mass spectrometry, we found that female L. lineolaris and L. elisus have a 4:10 ratio of hexyl butyrate to (E)-2-hexenyl butyrate that is reversed from the 10:1 ratio in female L. hesperus (males of the three species have ~10:1 ratio). These reversed ratios among females of the species suggest a behavioral role. Because both sexes have nearly equal amounts of the major volatiles, females should release more to attract males. This expectation was supported because L. hesperus females released more hexyl butyrate (mean of 86 ng/h) during the night (1800-0700 hours) than did males (<1 ng/h). We used slow-rotating pairs of traps to test the attraction of species to blends of the volatiles with a subtractive method to detect synergism. Each species' major butyrate ester was released at 3 μg/h, the minor butyrate according to its ratio, and (E)-4-oxo-2-hexenal at 2 μg/h. The resulting catches of only Lygus males suggest that (E)-4-oxo-2-hexenal is an essential sex pheromone component for all three species, (E)-2-hexenyl butyrate is essential for L. elisus and L. lineolaris, and hexyl butyrate is essential for L. hesperus. However, all three components are recognized by each species since ratios of the butyrate esters are critical for conspecific attraction and heterospecific avoidance by males and thus play a role in reproductive isolation among the three species. Because L. hesperus males and females are known to emit these major volatiles for repelling ant predators, our study links defensive allomones in Lygus bugs with an

  5. Calcium Availability Influences Litter Size and Sex Ratio in White-Footed Mice (Peromyscus leucopus)

    PubMed Central

    Schmidt, Christina M.; Hood, Wendy R.

    2012-01-01

    The production of offspring typically requires investment of resources derived from both the environment and maternal somatic reserves. As such, the availability of either of these types of resources has the potential to limit the degree to which resources are allocated to reproduction. Theory and empirical studies have argued that mothers modify reproductive performance relative to exogenous resource availability and maternal condition by adjusting size, number or sex of offspring produced. These relationships have classically been defined relative to availability of energy sources; however, in vertebrates, calcium also plays a critical role in offspring production, as a considerable amount of calcium is required to support the development of offspring skeleton(s). We tested whether the availability of calcium influences reproductive output by providing female white-footed mice with a low-calcium or standard diet from reproductive maturity to senescence. We then compared maternal skeletal condition and reproductive output, based on offspring mass, offspring number and litter sex ratio, between dietary treatments. Mothers on the low-calcium diet exhibited diminished skeletal condition at senescence and produced smaller and strongly female-biased litters. We show that skeletal condition and calcium intake can influence sex ratio and reproductive output following general theoretical models of resource partitioning during reproduction. PMID:22870218

  6. Mixture Analysis and Mammalian Sex Ratio Among Middle Pleistocene Mouflon of Arago Cave, France

    NASA Astrophysics Data System (ADS)

    Monchot, Hervé

    1999-09-01

    In archaeological studies, it is often important to be able assess sexual dimorphism and sex ratios in populations. Obtaining sex ratio is easy if each individual in the population can be accurately sexed through the use of one more objective variables. But this is often impossible, due to incompleteness of the osteological record. A modern statistical approach to handle this problem is Mixture Analysis using the method of maximum likelihood. It consists of determining how many groups are present in the sample, two in this case, in which proportions they occur, and to estimate the parameters accordingly. This paper shows the use of this method on vertebrate fossil populations in a prehistoric context with implications on prey acquisition by early humans. For instance, the analysis of mouflon bones from Arago cave (Tautavel, France) indicates that there are more females than males in the F layer. According to the ethology of the animal, this indicates that the hunting strategy could be the result of selective choice of the prey. Moreover, we may deduce the presence of Anteneandertalians on the site during spring and summer periods.

  7. Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio

    PubMed Central

    Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco

    2016-01-01

    Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population’s sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns. PMID:27441554

  8. The AKR gene family and modifying sex ratios in palms through abiotic stress responsiveness.

    PubMed

    Somyong, Suthasinee; Poopear, Supannee; Jomchai, Nukoon; Uthaipaisanwong, Pichahpuk; Ruang-Areerate, Panthita; Sangsrakru, Duangjai; Sonthirod, Chutima; Ukoskit, Kittipat; Tragoonrung, Somvong; Tangphatsornruang, Sithichoke

    2015-05-01

    Sex ratio (SR), the ratio of female inflorescences to total inflorescences, is one of the main yield components of oil palm (Elaeis guineensis Jacq). The SR quantitative trait locus (QTL) was recently identified on linkage (LG) 8 with a phenotype variance explained (PVE) of 11.3 %. The use of both genetic and physical mapping is one strategy for uncovering the genetic basis of the traits. Here, we report the construction of bacterial artificial chromosome (BAC) and fosmid libraries, and their use for physical mapping in oil palm. Combined, the libraries consist of more than 200,000 clones, representing 6.35 genome equivalents. Physical mapping at the SR locus was implemented by incorporating the published oil palm genome sequence and positive BAC/fosmid clones as identified by colony PCR screening. Based on the previously published sequences, the interval (about 184 kb) was comprised of 19 contigs of the known sequences (~117 kb, 64 %). After, combining the 454 pyrosequences of 15 positive clones and the previously published sequences, the known sequences were revealed to cover about 82 % of the interval (~150 kb), and were used for identifying the new markers by designing 35 gene-based and 23 simple sequence repeat (SSR)-amplified primers. As a result, a putative aldo-keto reductase gene (named EgAKR1) was revealed to be a promising candidate for sex ratio determination, via controlling female inflorescence number (11 % of PVE). This was predicted from the two newly identified polymorphic marker loci (mEgSSRsr8-21LB and mEgAKR1-9) designing from EgAKR1. The functions of AKR gene families in other plant species and our promoter analysis suggested that EgAKR1 may contribute to the sex ratio through abiotic stress responsiveness. PMID:25504196

  9. How can economic schemes curtail the increasing sex ratio at birth in China?

    PubMed Central

    Bhattacharjya, Debarun; Sudarshan, Anant; Tuljapurkar, Shripad; Shachter, Ross; Feldman, Marcus

    2010-01-01

    Fertility decline, driven by the one-child policy, and son preference have contributed to an alarming difference in the number of live male and female births in China. We present a quantitative model where people choose to sex-select because they perceive that married sons are more valuable than married daughters. Due to the predominant patrilocal kinship system in China, daughters-in-law provide valuable emotional and financial support, enhancing the perceived present value of married sons. We argue that inter-generational transfer data will help ascertain the extent to which economic schemes (such as pension plans for families with no sons) can curtail the increasing sex ratio at birth. PMID:21113272

  10. Phenobarbital plasma level/dose ratio in monotherapy. Influence of age, sex and dose.

    PubMed

    Durán, J A; Sánchez, A; Serrano, M I; Serrano, J S

    1988-05-01

    Phenobarbital plasma level/dose ratio (L/D) has been studied in 536 outpatients distributed in groups according to age, sex and drug dosage. Samples were obtained prior to the first morning dose. Plasma levels that correspond to the steady-state phase were determined by homogeneous enzymatic immunoassay (EMITR). From the results it must be pointed out: 1) An increase of L/D as the age increases within each group; 2) A decrease of L/D as the dose of phenobarbital increases in the overall sample; 3) Sex does not affect L/D in any of the subgroups studied; 4) For a given dose higher blood levels are reached in children 7 to 15 years old in our sample than in other comparable studies in Spain. PMID:3398650

  11. Sex ratios provide evidence for monozygotic twinning in the ring-tailed lemur, Lemur catta.

    PubMed

    St Clair, John; Campbell-Palmer, Roisin; Lathe, Richard

    2014-02-01

    Monozygotic (MZ) twinning is generally considered to be rare in species other than human. We inspected sex ratios in European zoo-bred ring-tailed lemurs (Lemur catta), revealing a significant excess of same-sex twins. Of 94 pairs, 60 (64%) were either both males or both females (p = .004). Application of the Weinberg differential rule argues that 27% of all twins in this species are MZ pairs. In this protected species, where twinning is commonplace (~50% of newborns are twins), the probable existence of frequent MZ twinning has ramifications for breeding programs aimed to maximize genetic diversity, and suggests that twin studies in a species other than human could have potential as a medical research tool. PMID:24384029

  12. Hamstrings to quadriceps peak torque ratios diverge between sexes with increasing isokinetic angular velocity.

    PubMed

    Hewett, Timothy E; Myer, Gregory D; Zazulak, Bohdanna T

    2008-09-01

    Our purpose was to determine if females demonstrate decreased hamstrings to quadriceps peak torque (H/Q) ratios compared to males and if H/Q ratios increase with increased isokinetic velocity in both sexes. Maturation disproportionately increases hamstrings peak torque at high velocity in males, but not females. Therefore, we hypothesised that mature females would demonstrate decreased H/Q ratios compared to males and the difference in H/Q ratio between sexes would increase as isokinetic velocity increased. Studies that analysed the H/Q ratio with gravity corrected isokinetic strength testing reported between 1967 and 2004 were included in our review and analysis. Keywords were hamstrings/quadriceps, isokinetics, peak torque and gravity corrected. Medline and Smart databases were searched combined with cross-checked bibliographic reference lists of the publications to determine studies to be included. Twenty-two studies were included with a total of 1568 subjects (1145 male, 423 female). Males demonstrated a significant correlation between H/Q ratio and isokinetic velocity (R=0.634, p<0.0001), and a significant difference in the isokinetic H/Q ratio at the lowest angular velocity (47.8+/-2.2% at 30 degrees /s) compared to the highest velocity (81.4+/-1.1% at 360 degrees /s, p<0.001). In contrast, females did not demonstrate a significant relationship between H/Q ratio and isokinetic velocity (R=0.065, p=0.77) or a change in relative hamstrings strength as the speed increased (49.5+/-8.8% at 30 degrees /s; 51.0+/-5.7% at 360 degrees /s, p=0.84). Gender differences in isokinetic H/Q ratios were not observed at slower angular velocities. However, at high knee flexion/extension angular velocities, approaching those that occur during sports activities, significant gender differences were observed in the H/Q ratio. Females, unlike males, do not increase hamstrings to quadriceps torque ratios at velocities that approach those of functional activities. PMID:17875402

  13. Hamstrings to quadriceps peak torque ratios diverge between sexes with increasing isokinetic angular velocity

    PubMed Central

    Hewett, Timothy E.; Myer, Gregory D.; Zazulak, Bohdanna T.

    2012-01-01

    Summary Our purpose was to determine if females demonstrate decreased hamstrings to quadriceps peak torque (H/Q) ratios compared to males and if H/Q ratios increase with increased isokinetic velocity in both sexes. Maturation disproportionately increases hamstrings peak torque at high velocity in males, but not females. Therefore, we hypothesised that mature females would demonstrate decreased H/Q ratios compared to males and the difference in H/Q ratio between sexes would increase as isokinetic velocity increased. Studies that analysed the H/Q ratio with gravity corrected isokinetic strength testing reported between 1967 and 2004 were included in our review and analysis. Keywords were hamstrings/quadriceps, isokinetics, peak torque and gravity corrected. Medline and Smart databases were searched combined with cross-checked bibliographic reference lists of the publications to determine studies to be included. Twenty-two studies were included with a total of 1568 subjects (1145 male, 423 female). Males demonstrated a significant correlation between H/Q ratio and isokinetic velocity (R = 0.634, p < 0.0001), and a significant difference in the isokinetic H/Q ratio at the lowest angular velocity (47.8 ± 2.2% at 30°/s) compared to the highest velocity (81.4 ± 1.1% at 360°/s, p < 0.001). In contrast, females did not demonstrate a significant relationship between H/Q ratio and isokinetic velocity (R = 0.065, p = 0.77) or a change in relative hamstrings strength as the speed increased (49.5 ± 8.8% at 30°/s; 51.0 ± 5.7% at 360°/s, p = 0.84). Gender differences in isokinetic H/Q ratios were not observed at slower angular velocities. However, at high knee flexion/extension angular velocities, approaching those that occur during sports activities, significant gender differences were observed in the H/Q ratio. Females, unlike males, do not increase hamstrings to quadriceps torque ratios at velocities that approach those of functional activities. PMID:17875402

  14. Winning the genetic lottery: biasing birth sex ratio results in more grandchildren.

    PubMed

    Thogerson, Collette M; Brady, Colleen M; Howard, Richard D; Mason, Georgia J; Pajor, Edmond A; Vicino, Greg A; Garner, Joseph P

    2013-01-01

    Population dynamics predicts that on average parents should invest equally in male and female offspring; similarly, the physiology of mammalian sex determination is supposedly stochastic, producing equal numbers of sons and daughters. However, a high quality parent can maximize fitness by biasing their birth sex ratio (SR) to the sex with the greatest potential to disproportionately outperform peers. All SR manipulation theories share a fundamental prediction: grandparents who bias birth SR should produce more grandoffspring via the favored sex. The celebrated examples of biased birth SRs in nature consistent with SR manipulation theories provide compelling circumstantial evidence. However, this prediction has never been directly tested in mammals, primarily because the complete three-generation pedigrees needed to test whether individual favored offspring produce more grandoffspring for the biasing grandparent are essentially impossible to obtain in nature. Three-generation pedigrees were constructed using 90 years of captive breeding records from 198 mammalian species. Male and female grandparents consistently biased their birth SR toward the sex that maximized second-generation success. The most strongly male-biased granddams and grandsires produced respectively 29% and 25% more grandoffspring than non-skewing conspecifics. The sons of the most male-biasing granddams were 2.7 times as fecund as those of granddams with a 50∶50 bias (similar results are seen in grandsires). Daughters of the strongest female-biasing granddams were 1.2 times as fecund as those of non-biasing females (this effect is not seen in grandsires). To our knowledge, these results are the first formal test of the hypothesis that birth SR manipulation is adaptive in mammals in terms of grandchildren produced, showing that SR manipulation can explain biased birth SR in general across mammalian species. These findings also have practical implications: parental control of birth SR has the

  15. Neotenic Phenotype and Sex Ratios Provide Insight into Developmental Pathways in Reticulitermes flavipes (Isoptera: Rhinotermitidae)

    PubMed Central

    Hu, Jian; Forschler, Brian T.

    2012-01-01

    Several thousand Reticulitermes flavipes (Kollar) including worker, nymph, soldier, neotenic and alate castes were collected from three pine logs brought into the laboratory on dates five years apart. The neotenics, all nymphoid, were divided into three groups based on the extent of cuticle pigmentation and termed regular neotenics (RN), black-headed neotenics (BHN) or black neotenics (BN). All castes, from Log A, in 2008, provided a neutral sex ratio except BHN (N = 378) and BN (N = 51) which were exclusively male while the soldiers (N = 466) were female-biased. This information suggests that there is a sex-linked bifurcation along the path for termite development with a male-biased neotenic or female-biased soldier as the choice. In contrast, termites collected in 2004 from Log B provided sex ratios that included a female biased RN (N = 1017), a neutral soldier (N = 258) and male biased BHN (N = 99) and workers (N = 54). Log C, collected in 2009, provided female biased soldiers (N = 32), RNs (N = 18) and BHNs (N = 4) and only male BN (N = 5). Eight laboratory cultures, ranging in age from five to 14 years old, also were sampled and all castes sexed. The census included a 14-year old queen-right colony, an 8-year old polyandrous colony and six colonies provided nymphs and male-biased worker populations. Together these data indicate a flexible caste determination system providing a unique opportunity for a better understanding of the flexible developmental options available in R. flavipes that we discuss relative to the literature on Reticulitermes ontogeny. PMID:26466543

  16. Neutrophil function and cortisol:DHEAS ratio in bereaved older adults.

    PubMed

    Khanfer, Riyad; Lord, Janet M; Phillips, Anna C

    2011-08-01

    Bereavement is a common life event for older adults and is associated with increased risk of morbidity and mortality, though the underlying reasons for this link are poorly understood. Although physical and emotional stressors and ageing are known to suppress immunity, few studies have explored the impact of bereavement upon immunity in the older population. We therefore hypothesised that the emotional stress of bereavement would suppress immune function, specifically neutrophil bactericidal activity, in older adults. A between-subjects design was used to examine the effect of recent bereavement (<2 months) on neutrophil function in elders. Participants were 24 bereaved and 24 age- and sex-matched non-bereaved controls all aged 65+ years. Neutrophil phagocytosis of Escherichia coli (E. coli) and stimulated superoxide production were assessed. Cortisol and dehydroepiandrosterone-sulphate (DHEAS) levels were determined in serum to assess potential mechanisms. Depressive and anxiety symptoms were measured by questionnaire. Neutrophil superoxide production was significantly reduced among the bereaved when challenged with E. coli (p=0.05), or phorbol 12-myristate 13-acetate (p=0.009). Further, the bereaved group had a significantly higher cortisol:DHEAS ratio compared to controls (p=0.03). There was no difference in neutrophil phagocytosis between the two groups. The psychological questionnaire results showed that the bereaved had significantly greater depressive and anxiety symptoms than the non-bereaved. The emotional stress of bereavement is associated with suppressed neutrophil superoxide production and with a raised cortisol:DHEAS ratio. The stress of bereavement exaggerates the age-related decline in HPA axis and combines with immune ageing to further suppress immune function, which may help to the explain increased risk of infection in bereaved older adults. PMID:21420485

  17. Sex Role Orientation Across the Adult Life Span.

    ERIC Educational Resources Information Center

    Zaks, Peggy M.; And Others

    It was hypothesized that four different "life lines" would affect sex role orientations, specifically intimacy, parenting, grandparenting, and work. Subjects were 74 men and 43 women, white, upper middle class with a mean education level of 14 years. Each participant completed a demographic questionnaire, the Bem Sex Role Inventory, a Life Events…

  18. Prevalence and Correlates of Sex Exchange Among a Nationally Representative Sample of Adolescents and Young Adults.

    PubMed

    Ulloa, Emilio; Salazar, Marissa; Monjaras, Lidia

    2016-07-01

    The present study examines prevalence and correlates of exchanging sex for drugs, money, food shelter, or other favors (sex exchange) among a nationally representative sample of youth and young adults. Adolescents and young adults (n = 11,620, 53% female, 47% male) from the National Longitudinal Study of Adolescent Health were used for the current sample. Participants completed in-home interviews at both waves. Results revealed that sex exchange was reported by 4.9% (n = 569) of the population in wave 2 or wave 3, and 4.6% (n = 26) of those who exchanged sex did so at both waves. More males reported exchanging sex than females (n = 332 versus n = 237). Respondents who reported child sexual abuse were more likely to exchange sex (95% CI 2.51-4.28, p < .05) than respondents who reported any other form of child abuse. Both males and females who engaged in sex exchange were at greater risk for sexually transmitted infections; however, the odds of ever exchanging sex were highest among males who ever had gonorrhea (OR = 6.2; 95% CI 3.75-10.3). Although sex exchange has been studied extensively among homeless and runaway youth, the current study reveals sex exchange also occurs in the general population. PMID:27266400

  19. Sex Differences in Seoul Virus Infection Are Not Related to Adult Sex Steroid Concentrations in Norway Rats

    PubMed Central

    Klein, Sabra L.; Bird, Brian H.; Glass, Gregory E.

    2000-01-01

    Field studies of hantavirus infection in rodents report that a higher percentage of infected individuals are males than females. To determine whether males were more susceptible to hantavirus infection than females, adult male and female Long Evans rats (Rattus norvegicus) were inoculated with doses of Seoul virus ranging from 10−4 to 106 PFU. The 50% infective doses (ID50) were not significantly different for male and female rats (100.05 and 100.8 PFU, respectively). To determine whether sex differences in response to infection were related to circulating sex steroid hormones, sex steroid concentrations were manipulated and antibody responses and virus shedding were assessed following inoculation with the ID90. Regardless of hormone treatment, males had higher anti-Seoul virus immunoglobulin G (IgG) and IgG2a (i.e., Th1) responses than females and IgG1 (i.e., Th2) responses similar to those of females. Males also shed virus in saliva and feces longer than females. Manipulation of sex steroids in adulthood did not alter immune responses or virus shedding, suggesting that sex steroids may organize adult responses to hantavirus earlier during ontogeny. PMID:10933735

  20. Exposure to widespread environmental endocrine disrupting chemicals and human sperm sex ratio.

    PubMed

    Jurewicz, Joanna; Radwan, Michał; Sobala, Wojciech; Radwan, Paweł; Jakubowski, Lucjusz; Wielgomas, Bartosz; Ligocka, Danuta; Brzeźnicki, Sławomir; Hanke, Wojciech

    2016-06-01

    In recent years, a trend toward a declining proportion of male births has been noted in several, but not all, industrialized countries. The underlying reason for the drop in the sex ratio is unclear, but one theory states that widespread environmental endocrine disrupting chemicals affecting the male reproductive system in a negative manner could be part of the explanation. The present study was designed to investigate whether the urinary phthalate, pyrethroids and polycyclic aromatic hydrocarbons metabolites concentrations were associated with sperm Y:X ratio. The study population consisted of 194 men aged under 45 years of age who attended infertility clinic in Lodz, Poland for diagnostic purposes with normal semen concentration of 20-300 mln/ml or with slight oligozoospermia (semen concentration of 15-20 mln/ml) (WHO, 1999). The Y:X ratio was assessed by fluorescent in situ hybridization. Urinary concentrations of 1-hydroxypyrene were measured by high performance liquid chromatography, phthalate metabolites were analyzed using a procedure based on the LC-MS/MS methods and metabolites of synthetic pyrethroids were assessed by gas chromatography ion-tap mass spectrometry method. After adjustment for potential confounders (past diseases, age, abstinence, smoking, alcohol consumption, sperm concentration, motility, morphology) 5OH MEHP, CDCCA to TDCCA and 1-OHP was negatively related to Y:X sperm chromosome ratio (p = 0.033, p < 0.001, p = 0.047 respectively). As this is the first study to elucidate the association between the level of metabolites of widespread environmental endocrine disrupting chemicals (phthalates, synthetic pyrethroids, polycyclic aromatic hydrocarbons) on sex chromosome ratio in sperm therefore, these findings require further replication in other populations. PMID:27031570

  1. Is There a Sex Ratio Difference in the Familial Aggregation of Specific Language Impairment? A Meta-Analysis

    ERIC Educational Resources Information Center

    Whitehouse, Andrew J. O.

    2010-01-01

    Purpose: Specific language impairment (SLI) is known to aggregate in families. Debate exists on whether the male sex presents an additional risk for SLI. This meta-analysis examined whether there is a sex ratio difference in the risk for impairment among family members of an SLI proband and whether this is mediated by assessment method (direct…

  2. Changes in American Adults' Reported Same-Sex Sexual Experiences and Attitudes, 1973-2014.

    PubMed

    Twenge, Jean M; Sherman, Ryne A; Wells, Brooke E

    2016-10-01

    We examined change over time in the reported prevalence of men having sex with men and women having sex with women and acceptance of those behaviors in the nationally representative General Social Survey of U.S. adults (n's = 28,161-33,728, ages 18-96 years), 1972-2014. The number of U.S. adults who had at least one same-sex partner since age 18 doubled between the early 1990s and early 2010s (from 3.6 to 8.7 % for women and from 4.5 to 8.2 % for men). Bisexual behavior (having sex with both male and female partners) increased from 3.1 to 7.7 %, accounting for much of the rise, with little consistent change in those having sex exclusively with same-sex partners. The increase in same-sex partners was larger for women than for men, consistent with erotic plasticity theory. Attitudes toward same-sex sexual behavior also became substantially more accepting, d = .75, between the early 1970s and early 2010s. By 2014, 49 % of American adults believed that same-sex sexual activity was "not wrong at all," up from 11 % in 1973 and 13 % in 1990. Controlling for acceptance reduced, but did not eliminate, the increase in same-sex behavior over time. Mixed effects (hierarchical linear modeling) analyses separating age, time period, and cohort showed that the trends were primarily due to time period. Increases in same-sex sexual behavior were largest in the South and Midwest and among Whites, were mostly absent among Blacks, and were smaller among the religious. Overall, same-sex sexual behavior has become both more common (or at least more commonly reported) and more accepted. PMID:27251639

  3. Mate choice and the operational sex ratio: an experimental test with robotic crabs.

    PubMed

    Hayes, C L; Callander, S; Booksmythe, I; Jennions, M D; Backwell, P R Y

    2016-07-01

    The operational sex ratio (OSR: sexually active males: receptive females) predicts the intensity of competition for mates. It is less clear, however, under what circumstances, the OSR predicts the strength of sexual selection - that is, the extent to which variation in mating success is attributable to traits that increase the bearer's attractiveness and/or fighting ability. To establish causality, experiments that manipulate the OSR are required. Furthermore, if it is possible to control for any OSR-dependent changes in the chosen sex (e.g. changes in male courtship), we can directly test whether the OSR affects the behaviour of the choosing sex (e.g. female choice decisions). We conducted female mate choice experiments in the field using robotic models of male fiddler crabs (Uca mjoebergi). We used a novel design with two females tested sequentially per trial. As in nature, the choice of the first female to mate therefore affected the mates available to the next female. In general, we detected significant sexual selection due to female choice for 'males' with larger claws. Importantly, the strength of sexual selection did not vary across five different OSR/density treatments. However, as the OSR decreased (hence the number of available males declined), females chose the 'males' with the largest claws available significantly more often than expected by chance. Possible reasons for this mismatch between the expected and observed effects of the OSR on the strength of sexual selection are discussed. PMID:27087241

  4. A synthetic sex ratio distortion system for the control of the human malaria mosquito.

    PubMed

    Galizi, Roberto; Doyle, Lindsey A; Menichelli, Miriam; Bernardini, Federica; Deredec, Anne; Burt, Austin; Stoddard, Barry L; Windbichler, Nikolai; Crisanti, Andrea

    2014-01-01

    It has been theorized that inducing extreme reproductive sex ratios could be a method to suppress or eliminate pest populations. Limited knowledge about the genetic makeup and mode of action of naturally occurring sex distorters and the prevalence of co-evolving suppressors has hampered their use for control. Here we generate a synthetic sex distortion system by exploiting the specificity of the homing endonuclease I-PpoI, which is able to selectively cleave ribosomal gene sequences of the malaria vector Anopheles gambiae that are located exclusively on the mosquito's X chromosome. We combine structure-based protein engineering and molecular genetics to restrict the activity of the potentially toxic endonuclease to spermatogenesis. Shredding of the paternal X chromosome prevents it from being transmitted to the next generation, resulting in fully fertile mosquito strains that produce >95% male offspring. We demonstrate that distorter male mosquitoes can efficiently suppress caged wild-type mosquito populations, providing the foundation for a new class of genetic vector control strategies. PMID:24915045

  5. A synthetic sex ratio distortion system for the control of the human malaria mosquito

    PubMed Central

    Galizi, Roberto; Doyle, Lindsey A.; Menichelli, Miriam; Bernardini, Federica; Deredec, Anne; Burt, Austin; Stoddard, Barry L.; Windbichler, Nikolai; Crisanti, Andrea

    2014-01-01

    It has been theorized that inducing extreme reproductive sex ratios could be a method to suppress or eliminate pest populations. Limited knowledge about the genetic makeup and mode of action of naturally occurring sex distorters and the prevalence of co-evolving suppressors has hampered their use for control. Here we generate a synthetic sex distortion system by exploiting the specificity of the homing endonuclease I-PpoI, which is able to selectively cleave ribosomal gene sequences of the malaria vector Anopheles gambiae that are located exclusively on the mosquito’s X chromosome. We combine structure-based protein engineering and molecular genetics to restrict the activity of the potentially toxic endonuclease to spermatogenesis. Shredding of the paternal X chromosome prevents it from being transmitted to the next generation, resulting in fully fertile mosquito strains that produce >95% male offspring. We demonstrate that distorter male mosquitoes can efficiently suppress caged wild-type mosquito populations, providing the foundation for a new class of genetic vector control strategies. PMID:24915045

  6. Girl or boy? Prenatal lead, cadmium and mercury exposure and the secondary sex ratio in the ALSPAC study.

    PubMed

    Taylor, C M; Golding, J; Emond, A M

    2014-07-01

    The aim of this study was to evaluate the effect of prenatal exposure to lead, cadmium and mercury levels on the secondary sex ratio. Whole blood samples were collected from pregnant women enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) study at a median gestational age of 11 weeks and were analyzed for lead, cadmium and mercury. Regression analysis was used to identify associations between maternal lead, cadmium and mercury levels and the secondary sex ratio with adjustment for confounders. There was no evidence for associations between maternal lead, cadmium or mercury levels and the secondary sex ratio in this sample. It appears unlikely that alterations in the secondary sex ratio are influenced by exposure to heavy metals, but further work should be done in large cohorts in other countries to confirm these findings. PMID:24703858

  7. Multi-factorial influences on sex ratio: a spatio-temporal investigation of endocrine disruptor pollution and neighborhood stress

    PubMed Central

    McDonald, Ewan; Watterson, Andrew; Tyler, Andrew N; McArthur, John; Scott, E Marion

    2014-01-01

    Background: It is suggested the declining male birth proportion in some industrialized countries is linked to ubiquitous endocrine disruptor exposure. Stress and advanced parental age are determinants which frequently present positive findings. Multi-factorial influences on population sex ratio are rarely explored or tested in research. Objectives: To test the hypothesis that dual factors of pollution and population stress affects sex proportion at birth through geographical analysis of Central Scotland. Methods: The study incorporates the use of Geographical Information Systems (GIS) tools to overlay modeled point source endocrine disruptor air emissions with “small-area” data on multiple deprivation (a proxy measurement of stress) and birth sex. Historical review of regional sex ratio trends presents additional data on sex ratio in Scotland to consider. Results: There was no overall concentration in Central Scotland of low sex ratio neighborhoods with areas where endocrine disruptor air pollution and deprivation or economic stress were high. Historical regional trends in Scotland (from 1973), however, do show significantly lower sex ratio values for populations where industrial air pollution is highest (i.e. Eastern Central Scotland). Conclusions: Use of small area data sets and pollution inventories is a potential new method of inquiry for reproductive environmental and health protection monitoring and has produced interesting findings. PMID:25000111

  8. Sex differences in the genetic and environmental influences on childhood conduct disorder and adult antisocial behavior.

    PubMed

    Meier, Madeline H; Slutske, Wendy S; Heath, Andrew C; Martin, Nicholas G

    2011-05-01

    Sex differences in the genetic and environmental influences on childhood conduct disorder and adult antisocial behavior were examined in a large community sample of 6,383 adult male, female, and opposite-sex twins. Retrospective reports of childhood conduct disorder (prior to 18 years of age) were obtained when participants were approximately 30 years old, and lifetime reports of adult antisocial behavior (antisocial behavior after 17 years of age) were obtained 8 years later. Results revealed that either the genetic or the shared environmental factors influencing childhood conduct disorder differed for males and females (i.e., a qualitative sex difference), but by adulthood, these sex-specific influences on antisocial behavior were no longer apparent. Further, genetic and environmental influences accounted for proportionally the same amount of variance in antisocial behavior for males and females in childhood and adulthood (i.e., there were no quantitative sex differences). Additionally, the stability of antisocial behavior from childhood to adulthood was slightly greater for males than females. Though familial factors accounted for more of the stability of antisocial behavior for males than females, genetic factors accounted for the majority of the covariation between childhood conduct disorder and adult antisocial behavior for both sexes. The genetic influences on adult antisocial behavior overlapped completely with the genetic influences on childhood conduct disorder for both males and females. Implications for future twin and molecular genetic studies are discussed. PMID:21319923

  9. The Effect of Sex Labels on Adults' Knowledge of Infant Development.

    ERIC Educational Resources Information Center

    Paludi, Michele, A.; Gullo, Dominic F.

    1987-01-01

    Adults indicated on questionnaires the age at which they believed infants were first able to perform various developmental skills. Some questionnaires asked about "boys," some about "girls," and some about "babies." Contrary to previous findings, sex labels did not affect adults' rating of behaviors. (Author/LHW)

  10. Poverty, Rape, Adult/Teen Sex: Why "Pregnancy Prevention" Programs Don't Work.

    ERIC Educational Resources Information Center

    Males, Mike

    1994-01-01

    Stephen Caldas assumes that modern "teenage" sex and pregnancy are deviant, isolatable behaviors. However, teenage and adult sexual behaviors are so intertwined at the personal and societal levels that there is no distinct teenage phenomenon amenable to school intervention. Attempting to preach values contradicting the values adults practice is…

  11. Adults' Complicity in Limiting Students' Understanding of Sex, Gender and Sexuality at School

    ERIC Educational Resources Information Center

    Mayo, J. B., Jr.

    2016-01-01

    This article is a commentary on the seven papers in this special issue of "Sex Education." A compelling theme interwoven throughout all the articles in subtle and explicit ways is the role that adults play in the lives of students, particularly in the ways in which adults impact how students enact and respond to the multiple…

  12. Beyond Sex Education: How Adults Relate to Children's Sensuality.

    ERIC Educational Resources Information Center

    Fogel, Alan

    Current cultural attitudes toward children's sexuality resemble attitudes toward adults' sexuality; there is an emphasis on purely genital and orgasmic pleasure. Adults and children need warmth, physical contact, and a sense of belonging for which genital stimulation may be unnecessary or inappropriate. Children's sexual advances to adults, as…

  13. Behavioral and physiological female responses to male sex ratio bias in a pond-breeding amphibian

    PubMed Central

    2012-01-01

    Introduction The phenomenon of sexual conflict has been well documented, and in populations with biased operational sex ratios the consequences for the rarer sex can be severe. Females are typically a limited resource and males often evolve aggressive mating behaviors, which can improve individual fitness for the male while negatively impacting female condition and fitness. In response, females can adjust their behavior to minimize exposure to aggressive mating tactics or minimize the costs of mating harassment. While male-male competition is common in amphibian mating systems, little is known about the consequences or responses of females. The red-spotted newt (Notophthalmus viridescens) is a common pond-breeding amphibian with a complex, well-studied mating system where males aggressively court females. Breeding populations across much of its range have male-biased sex ratios and we predicted that female newts would have behavioral mechanisms to mitigate mating pressure from males. We conducted four experiments examining the costs and behavioral responses of female N. viridescens exposed to a male-biased environment. Results In field enclosures, we found that female newts exposed to a male-biased environment during the five-month breeding season ended with lower body condition compared to those in a female-biased environment. Shorter-term exposure to a male-biased environment for five weeks caused a decrease in circulating total leukocyte and lymphocyte abundance in blood, which suggests females experienced physiological stress. In behavioral experiments, we found that females were more agitated in the presence of male chemical cues and females in a male-biased environment spent more time in refuge than those in a female-biased environment. Conclusions Our results indicate that male-biased conditions can incur costs to females of decreased condition and potentially increased risk of infection. However, we found that females can also alter their behavior and

  14. Effect of sex ratios, spiking and extra artificial insemination on the breeding efficiency of broiler breeders.

    PubMed

    Végi, Barbara; Váradi, Eva; Szőke, Zsuzsanna; Barna, Judit

    2013-09-01

    Since early fertility decline is a permanent problem of broiler breeders, the aim of this study was to test the effects of various sex ratios, spiking strategies and additional artificial inseminations (AI) on their breeding efficiency. Six breeder flocks were analysed during the whole reproduction cycle. In Flock A the sex ratio was maintained at 10% during the whole cycle (control), while in Flock B the number of males was increased to a final ratio of 16%. In Flocks C (technological control), D, E and F the ratio of males was gradually decreased from 10% to 6.5% until the end of the cycle. Moreover, at the age of 44 weeks in Flocks D and E 50 and 100% of cockerels were replaced by young ones, respectively, while in Flock F additional artificial inseminations were applied in the second half of the reproduction cycle. The increase of sperm transport was successful only in Groups B (increase in male numbers) and D (50% replacement of old cockerels with young ones); however, it was not sufficient for increasing the fertility rates in either group. Nor did additional artificial inseminations (Flock F) have an effect on fertility. As a conclusion, it can be established that increasing the sperm count in the hens' oviducts in any way could not improve fertility in the last third of the production cycle. The results also suggest that the expensive and labour-intensive spiking technique used in broiler breeder management is useless. The prime factor responsible for the shortened persistence of fertility may be the reduced ability of the female oviduct to accept and store sperm. PMID:23921351

  15. A framework for analyzing sex-selective abortion: the example of changing sex ratios in Southern Caucasus

    PubMed Central

    Hohmann, Sophie A; Lefèvre, Cécile A; Garenne, Michel L

    2014-01-01

    The paper proposes a socioeconomic framework of supply, demand, and regulation to explain the development of sex-selective abortion in several parts of the world. The framework is then applied to three countries of southern Caucasus (Armenia, Azerbaijan, and Georgia) where sex-selective abortion has developed since the collapse of the Soviet Union. The authors argue that sex-selective abortion cannot be explained simply by patriarchal social systems, sex discrimination, or son preference. The emphasis is put on the long-term acceptability of abortion in the region, on acceptability of sex-screening by both the medical establishment and by the population, on newly imported techniques of sex-screening, and on the changing demand for children associated with the major economic and social changes that followed the dismantlement of the Soviet Union. PMID:25349481

  16. SEX RATIO AT BIRTH AND THE IDEAL FAMILY IN CHI LINH DISTRICT, VIETNAM

    PubMed Central

    Thuy Duong, Doan Thi

    2016-01-01

    Chi Linh district, which locates in the Red Delta River region, has been recognized as the “hot pot” of high sex ratio at birth in Vietnam. This paper used community-based periodic Demographic-Epidemiologic Surveillance System (CHILILAB) to describe sex ratio at birth (SRB) and identify social - economic factors that related to the SRB. A total 5,940 births born from August 1, 2004 to August 31, 2011 was included in analysis. The SRB of 116.6 boys/100 girls (CI: 110.7 – 122.5) was significantly higher than normal. SRB were found high among second child having only older sister(s), among third child and higher birth order, among mothers who were 35 years and older, running small business or homemakers. Interestingly, a SRB of 91.4 boys/100 girls (CI: 81.8 – 102) was found among second children having an older brother, this is significantly lower than the normal level. Further research should be done to assert if abortion is practiced both to have a son and to have a daughter. PMID:27499813

  17. Male-biased sex ratios of fish embryos near a pulp mill: temporary recovery after a short-term shutdown.

    PubMed Central

    Larsson, D G Joakim; Förlin, Lars

    2002-01-01

    In a previous study we showed that broods from the viviparous eelpout Zoarces viviparus were significantly male biased in 1998 in the vicinity of a large kraft pulp mill on the Swedish Baltic coast. One suggested hypothesis was that masculinizing compounds in the effluent were affecting gonadal differentiation of the embryos, resulting in skewed sex ratios. In this article, we present further evidence for a causal relationship between the exposure to the effluent and the male-biased sex ratios. Analyses of historical samples showed that the eelpout produced male-biased broods close to the mill in 1997 in addition to 1998. During 1999, the mill was shut down for 17 days, coinciding with the period when the gonads of the eelpout embryos differentiate. Subsequently, in the fall of 1999, the sex ratios were no longer male biased; however, the following year (2000), a significant male bias reappeared. Investigations at 13 sites for up to 4 years showed a relatively stable sex ratio around 50/50, with the exceptions by the mill and with few observations of deviating ratios at other sites. Several reports document endocrine disturbances in fish near pulp and paper mills, including the expression of male secondary sex characters in female fish. The repeatedly identified male bias at the investigated mill, the normalization after mill shutdown, and the reappearance the following year indicate that pulp mill effluents also can affect sex ratios of nearby fish. PMID:12153752

  18. The Relationship Between Non-Medical Use of Prescription Opioids and Sex Work Among Adults in Residential Substance Use Treatment.

    PubMed

    Matusiewicz, Alexis K; Ilgen, Mark A; Bonar, Erin E; Price, Amanda; Bohnert, Amy S B

    2016-05-01

    High rates of substance use (e.g., alcohol, cocaine, heroin) have been documented among individuals who engage in sex work (SW), and adults seeking substance use disorder (SUD) treatment frequently report prior engagement in SW. Non-medical use of prescription opioids (NMUPO) has increased over the last decade, but little is known about the relationship between NMUPO with sex exchange. The purpose of this study was to describe the prevalence of recent SW among patients at a large residential SUD treatment center and examine the association between NMUPO and SW. Approximately 14% of 588 adults reported involvement in SW in the month prior to treatment. NMUPO was more common among those with a history of SW (95% of sex workers vs. 74% of non-sex-workers), and this association remained statistically significant after controlling for demographic factors, other substance use and psychiatric symptom severity (odds ratio=3.38). SW is relatively common among patients in residential SUD treatment, and is associated with greater psychiatric severity and more extensive substance use, including alarming rates of NMUPO. Addiction treatment for individuals involved in SW may benefit from the addition of content related to NMUPO. PMID:26979551

  19. Sex role identity in young adults: its parental antecedents and relation to ego development.

    PubMed

    Costos, D

    1986-03-01

    This study, inspired by Block's (1973) work, was designed to enable one to examine how ego development and socialization experience interact in relation to sex role identity. Sex role identity was measured via the Bem Sex Role Inventory, and socialization practices were measured via the Block Child-Rearing Practices Report. Both measures were scaled so as to yield scores on agency, communion, and androgyny. Ego development was assessed via Loevinger's Sentence Completion Test of Ego Development. The sample consisted of 120 young adult men and women, married and single. Analyses revealed that the predictive power of the variables differed by sex. Ego development was predictive of sex role identity in men but not women, whereas socialization practices were predictive of sex role identity in women but not men. The results were seen as supporting Chodorow's (1974) position regarding the differing socialization experiences of men and women. PMID:3701594

  20. Depression, Sex and Gender Roles in Older Adult Populations: The International Mobility in Aging Study (IMIAS)

    PubMed Central

    Vafaei, Afshin; Ahmed, Tamer; Freire, Aline do N. Falcão; Zunzunegui, Maria Victoria; Guerra, Ricardo O.

    2016-01-01

    Objectives To assess the associations between gender roles and depression in older men and women and whether gender roles are independent risk factors for depression. Methods International cross-sectional study of adults between 65 and 74 years old (n = 1,967). Depression was defined by a score of 16 or over in the Center for Epidemiologic Studies Depression Scale (CES-D). A validated 12-item Bem Sex Role Inventory (BSRI) was used to classify participants in gender roles (Masculine, Feminine, Androgynous, and Undifferentiated) using research site medians of femininity and masculinity as cut-off points. Poisson regressions were fitted to estimate the prevalence ratios (PR) of depression for each gender role compared to the masculine role, adjusting for sex, sufficiency of income, education, marital status, self-rated health, and chronic conditions. Results Among men, 31.2% were androgynous, 26% were masculine, 14.4% were feminine, and 28.4% were undifferentiated; among women, the corresponding percentages were 32.7%, 14.9%, 27%, and 25.4%. Both in men and in women, depressive symptoms (CES-D≥16) were more prevalent in those endorsing the undifferentiated type, compared to masculine, feminine or androgynous groups. However, after adjusting for potential confounders, compared to the masculine group only those endorsing the androgynous role were 28% less likely to suffer from depression: PR of 0.72 (95% CI: 0.55–0.93). In fully adjusted models, prevalence rates of depression were not different from masculine participants in the two other gender groups of feminine and undifferentiated. Conclusions Androgynous roles were associated with lower rates of depression in older adults, independently of being a man or a woman. PMID:26771828

  1. The Influence of Alcohol Consumption in Conjunction with Sex Hormone Deficiency on Ca/P Ratio in Rats

    PubMed Central

    Lodi, Karina Bortolin; Marchini, Adriana Mathias Pereira da Silva; Santo, Ana Maria do Espírito; Rode, Sigmar de Mello; Marchini, Leonardo; da Rocha, Rosilene Fernandes

    2016-01-01

    Deficiency of sex hormones and excessive alcohol consumption are factors that have been related to alterations in the pattern of bone mineralization and osteoporosis. The aim of this study was to evaluate possible alterations in the calcium/phosphorus (Ca/P) ratio in the femur of rats subjected to sex hormone deficiency and/or alcohol consumption. Methods. Female and male Wistar rats (n = 108) were divided into ovariectomized (Ovx), orchiectomized (Orx), or sham-operated groups and subdivided according to diet: alcoholic diet (20% alcohol solution), isocaloric diet, and ad libitum diet. The diets were administered for 8 weeks. The Ca/P ratio in the femur was analyzed by energy dispersive micro-X-ray spectrometer (μEDX). Results. Consumption of alcohol reduced the Ca/P ratio in both females and males. The isocaloric diet reduced the Ca/P ratio in females. In groups with the ad libitum diet, the deficiency of sex hormones did not change the Ca/P ratio in females or males. However, the combination of sex hormone deficiency and alcoholic diet presented the lowest values for the Ca/P ratio in both females and males. Conclusions. There was a reduced Ca/P ratio in the femur of rats that consumed alcohol, which was exacerbated when combined with a deficiency of sex hormones. PMID:27073396

  2. Sex Differences in Substance Use Among Adult Emergency Department Patients: Prevalence, Severity, and Need for Intervention

    PubMed Central

    Beaudoin, Francesca L.; Baird, Janette; Liu, Tao; Merchant, Roland C.

    2016-01-01

    Background Substance use is prevalent among emergency department (ED) patients, and sex has been implicated as an important factor in the etiology, pathophysiology, sequelae, and treatment of substance use disorders. However, additional information is needed about the epidemiology of substance use as it relates to sex among ED patients. Objectives This study examined sex differences in the prevalence and severity of self-reported tobacco, alcohol, and drug use among adult ED patients. Methods A random sample of English- or Spanish-speaking, non–critically ill or injured, 18- to 64-year-old patients was approached at two urban EDs and asked to self-report their lifetime and past 3-month tobacco, alcohol, and drug use. Participants completed the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) using an audio computer-assisted self-interview. Participants were categorized by their substance severity (ASSIST score) and need for a brief or more intensive intervention per World Health Organization recommendations. Substance misuse prevalence, frequency, severity, and need for interventions were compared between sexes by substance category. Multivariable logistic regression models were used to examine the association between sexes and the need for intervention after adjusting for sociodemographic characteristics. Results Of the 6,432 participants in the study, the median age was 37 years (interquartile range = 26 to 48 years), and 56.6% were female. Overall, lifetime, and past 3-month use was higher for men across all substances (tobacco, alcohol, and drugs). Among those reporting past 3-month use, the frequency of use was similar between sexes for tobacco and all drugs, but men reported more frequent alcohol use. Men had higher mean ASSIST scores compared to women, 30.3 (standard error [SE] ± 0.8) vs. 21.1 (SE ± 0.5); mean difference 9.2 (95% confidence interval [CI] = 7.4 to 10.9). The need for any intervention (brief or intensive) was similar

  3. Estimation of sex from the upper limb measurements of Sudanese adults.

    PubMed

    Ahmed, Altayeb Abdalla

    2013-11-01

    Sex estimation is the first biological attribute needed for personal identification from mutilated and amputated limbs or body parts in medical-legal autopsies. Populations have different sizes and proportions that affect the anthropometric assessment of sex. Relatively few published works assess the accuracy of sex estimation from soft tissue measurements of upper limb parts, except for the hand and its components, but these studies involve a limited range of global populations. The current study aimed to assess the degree of sexual dimorphism in upper limb measurements and the accuracy of using these measurements for sex estimation in a contemporary adult Sudanese population. The upper arm length, ulnar length, wrist breadth, hand length, and hand breadth of 240 right-handed Sudanese subjects (120 males and 120 females) aged between 25 and 30 years were measured by international anthropometric standards. Demarking points, sexual dimorphism indices and discriminant functions were developed from 200 subjects (100 males and 100 females) who composed the study group. All variables were sexually dimorphic. The ulnar length, wrist breadth and hand breadth significantly contributed to sex estimation. Forearm dimensions showed a higher accuracy for sex estimation than hand dimensions. Cross-validated sex classification accuracy ranged between 78.5% and 89.5%. The reliability of these standards was assessed in a test sample of 20 males and 20 females, and the results showed accuracy between 77.5% and 90%. This study provides new forensic standards for sex estimation from upper limb measurements of Sudanese adults. PMID:24237816

  4. Counseling Adult Sex Offenders: Unique Challenges and Treatment Paradigms.

    ERIC Educational Resources Information Center

    Priest, Ronnie; Smith, Annalee

    1992-01-01

    Reviews current definitions and research literature related to characteristics of adults who sexually victimize children. Presents discussion of pedophilia as a sexual deviation. Examines treatment issues that may confront counselors engaged in treating adults who sexually victimize children and discusses implications for practitioners. (Author/NB)

  5. Risky Sex Behavior and Substance Use among Young Adults.

    ERIC Educational Resources Information Center

    Staton, Michele; Leukefeld, Carl; Logan, T. K.; Zimmerman, Rick; Lynam, Donald; Milich, Richard; Martin, Catherine; McClanahan, Karen; Clayton, Richard

    1999-01-01

    Examines the relationship between substance use during adolescence and HIV risk behavior among young adults ages 19 to 21 with and without a college education. Results indicate that increased use of alcohol and marijuana at younger ages is related to riskier sexual activity as well as increased use of alcohol and marijuana as young adults.…

  6. Mercury elimination rates for adult northern pike Esox lucius: evidence for a sex effect

    USGS Publications Warehouse

    Madenjian, Charles P.; Blanchfield, Paul J.; Hrenchuk, Lee E.; Van Walleghem, Jillian L. A.

    2014-01-01

    We examined the effect of sex on mercury elimination in fish by monitoring isotope-enriched mercury concentrations in the muscle tissue of three adult female and three adult male northern pike Esox lucius, which had accumulated the isotope-enriched mercury via a whole-lake manipulation and were subsequently moved to a clean lake. Mercury elimination rates for female and male northern pike were estimated to be 0.00034 and 0.00073 day−1, respectively. Thus, males were capable of eliminating mercury at more than double the rate than that of females. To the best of our knowledge, our study represents the first documentation of mercury elimination rates varying between the sexes of fish. This sex difference in elimination rates should be taken into account when comparing mercury accumulation between the sexes of fish from the same population. Further, our findings should eventually lead to an improved understanding of mechanisms responsible for mercury elimination in vertebrates.

  7. Sex Differences in Responsiveness to Babies among Mature Adults.

    ERIC Educational Resources Information Center

    Feldman, S. Shirley; Nash, Sharon Churnin

    1979-01-01

    Interest in babies was assessed in 30 parents of adolescents, 28 parents whose grown children were no longer living at home, and 26 grandparents of an infant. Measures included responsivity to an unfamiliar baby in a waiting room situation, interest in pictures of babies, and a sex-role self-concept inventory. (JMB)

  8. Family Experiences of Young Adult Sex Offender Registration

    ERIC Educational Resources Information Center

    Comartin, Erin B.; Kernsmith, Poco D.; Miles, Bart W.

    2010-01-01

    Since 1994, policies have been instituted throughout the United States that require sex offenders to register their personal information with law enforcement officials (Jacob Wetterling Crimes against Children and Sexually Violent Offender Registration Program, 1994). With the passage of additional laws, this information is now available to the…

  9. Sex-related alcohol expectancies and high-risk sexual behavior among drinking adults in Kampala, Uganda

    PubMed Central

    Nash, Scott D.; Katamba, Achilles; Mafigiri, David Kaawa; Mbulaiteye, Sam M.; Sethi, Ajay K

    2015-01-01

    Alcohol consumption, a risk factor for HIV transmission in sub-Saharan Africa, is considered high in Uganda. The study was conducted to determine whether sex-related expectations about the effects of alcohol help explain the association between alcohol use and risky sexual behaviors in a population-based sample of adults in Kampala. A two-stage sampling procedure was used to identify residents in one division of Kampala for a cross-sectional study. Associations between alcohol use (current and higher-risk drinking) and high-risk sexual behaviors (multiple regular partners and casual sex) were tested. Final models included a sex-related alcohol outcome expectancy (AOE) summary score. In age-sex-adjusted models, having multiple regular partners was associated with current drinking (Odds Ratio (OR)=2.76, 95% Confidence Intervals (CI)=1.15, 6.63) and higher-risk drinking (OR=3.35, 95%CI=1.28,8.71). Associations were similar but not statistically significant for having a causal sex partner. Sex-related AOE were associated with both alcohol use and high-risk sexual behavior and attenuated relationships between multiple regular partners and both current drinking (OR=1.94, 95%CI=0.57,6.73) and higher-risk drinking (OR=2.44, 95%CI=0.68,8.80). In this setting sexual behaviors related with alcohol consumption were explained, in part, by sex-related expectations about the effects of alcohol. These expectations could be an important component to target in HIV education campaigns. PMID:26315308

  10. Where have all the young men gone? Using sex ratios to measure fetal death rates.

    PubMed

    Sanders, Nicholas J; Stoecker, Charles

    2015-05-01

    Fetal health is an important consideration in policy formation. Unfortunately, a complete census of fetal deaths, an important measure of overall fetal health, is infeasible, and available data are selectively observed. We consider this issue in the context of the Clean Air Act Amendments of 1970 (CAAA), one of the largest and most influential environmental regulations in the history of the United States. We discuss a model of potential bias in measuring observed fetal deaths, and present the sex ratio of live births as an alternative fetal health endpoint, taking advantage of the finding that males are more vulnerable to side effects of maternal stress in utero. We find the CAAA caused substantial improvements in fetal health, in addition to previously identified reductions in post-natal mortality. PMID:25655338

  11. Effect of separating bull semen into X and Y chromosome-bearing fractions on the sex ratio of resulting embryos.

    PubMed Central

    Hagele, W C; Hare, W C; Singh, E L; Grylls, J L; Abt, D A

    1984-01-01

    Seventy-six, day 12 to day 15 bovine embryos, collected from 14 donors which had been inseminated with either X or Y chromosome-bearing spermatozoa fractions of semen separated by a thermal convection counterstreaming sedimentation and forced convection galvanization process, were processed for sexing by chromosomal analysis. Fifty-seven embryos were sexed; 20 from Y chromosome-bearing and 37 from X chromosome-bearing fractions of semen. Statistical analysis of the sexing data indicated that there was no significant difference in the male: female ratio for donors receiving male fractions compared to those receiving female fractions. The Y chromosome-bearing fractions produced a male: female ratio that was indistinguishable from the expected 1:1 ratio. However, the X chromosome-bearing fractions of semen produced a highly significant deviation from the expected 1:1 ratio towards the male. PMID:6478299

  12. Effect of separating bull semen into X and Y chromosome-bearing fractions on the sex ratio of resulting embryos.

    PubMed

    Hagele, W C; Hare, W C; Singh, E L; Grylls, J L; Abt, D A

    1984-07-01

    Seventy-six, day 12 to day 15 bovine embryos, collected from 14 donors which had been inseminated with either X or Y chromosome-bearing spermatozoa fractions of semen separated by a thermal convection counterstreaming sedimentation and forced convection galvanization process, were processed for sexing by chromosomal analysis. Fifty-seven embryos were sexed; 20 from Y chromosome-bearing and 37 from X chromosome-bearing fractions of semen. Statistical analysis of the sexing data indicated that there was no significant difference in the male: female ratio for donors receiving male fractions compared to those receiving female fractions. The Y chromosome-bearing fractions produced a male: female ratio that was indistinguishable from the expected 1:1 ratio. However, the X chromosome-bearing fractions of semen produced a highly significant deviation from the expected 1:1 ratio towards the male. PMID:6478299

  13. Effects of local extrinsic mortality rate, crime and sex ratio on preventable death in Northern Ireland

    PubMed Central

    Uggla, Caroline; Mace, Ruth

    2015-01-01

    Background and objectives: Individual investment in health varies greatly within populations and results in significant differences in the risk of preventable death. Life history theory predicts that individuals should alter their investment in health (somatic maintenance) in response to ecological cues that shift the perceived fitness payoffs to such investments. However, previous research has failed to isolate the effects of different ecological factors on preventable death, and has often relied on macro-level data without individual controls. Here, we test some key predictions concerning the local ecology—that higher extrinsic mortality rate (EMR), crime rate and mate-scarcity (male/female-biased sex ratio) at the ward-level—will be associated with a higher risk of preventable death. Methodology: We use census-based data from Northern Ireland (n = 927 150) on preventable death during an 8.7-year period from the 2001 Census and run Cox regressions for (i) accident/suicide or alcohol-related death and (ii) deaths from preventable diseases, for men and women separately, controlling for a wide range of individual variables. Results: We find evidence of ward-level EMR and crime rate being positively associated with preventable death among men, particularly men with low socioeconomic position. There was a tentative relationship between male-biased sex ratio and preventable death among women, but not among men. Conclusion and implications: Both behaviours that might lead to ‘risky’ death and health neglect might be adaptive responses to local ecologies. Efforts to reduce crime might be as effective as those to reduce extrinsic mortality, and both could have positive effects on various health behaviours. PMID:26338679

  14. Couples’ Urinary Bisphenol A and Phthalate Metabolite Concentrations and the Secondary Sex Ratio

    PubMed Central

    Bae, Jisuk; Kim, Sungduk; Kannan, Kurunthachalam; Buck Louis, Germaine M.

    2015-01-01

    With limited research focusing on non-persistent chemicals as exogenous factors affecting human sex selection, this study aimed to evaluate the association of urinary bisphenol A (BPA) and phthalate metabolite concentrations with the secondary sex ratio (SSR), defined as the ratio of male to female live births. The current analysis is limited to singleton live births (n=220, 43.9%) from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study, which enrolled couples upon discontinuing contraception and followed while trying for pregnancy and through delivery those achieving pregnancy. Using modified Poisson regression models accounting for potential confounders, we estimated the relative risks (RRs) of a male birth per standard deviation change in the log-transformed maternal, paternal, and couple urinary BPA and 14 phthalate metabolite concentrations (ng/mL) measured upon enrollment. When maternal and paternal chemical concentrations were modeled jointly, paternal BPA (RR, 0.77; 95% confidence interval [CI], 0.62–0.95) and mono-isobutyl phthalate (RR, 0.82; 95% CI, 0.67–1.00) were significantly associated with a female excess. Contrarily, maternal BPA (RR, 1.16; 95% CI, 1.03–1.31), mono-isobutyl phthalate (RR, 1.28; 95% CI, 1.06–1.54), mono-benzyl phthalate (RR, 1.31; 95% CI, 1.08–1.58), and mono-n-butyl phthalate (RR, 1.24; 95% CI, 1.01–1.51) were significantly associated with a male excess. These findings underscore varying patterns for the SSR in relation to parental exposures. Given the absence of previous investigation, these partner-specific associations of non-persistent chemicals with the SSR need future corroboration. PMID:25677702

  15. Couples' urinary bisphenol A and phthalate metabolite concentrations and the secondary sex ratio.

    PubMed

    Bae, Jisuk; Kim, Sungduk; Kannan, Kurunthachalam; Buck Louis, Germaine M

    2015-02-01

    With limited research focusing on non-persistent chemicals as exogenous factors affecting human sex selection, this study aimed to evaluate the association of urinary bisphenol A (BPA) and phthalate metabolite concentrations with the secondary sex ratio (SSR), defined as the ratio of male to female live births. The current analysis is limited to singleton live births (n=220, 43.9%) from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study, in which couples discontinuing contraception with the intention of becoming pregnant were enrolled and followed while trying for pregnancy and through delivery for those achieving pregnancy. Using modified Poisson regression models accounting for potential confounders, we estimated the relative risks (RRs) of a male birth per standard deviation change in the log-transformed maternal, paternal, and couple urinary BPA and 14 phthalate metabolite concentrations (ng/mL) measured upon enrollment. When maternal and paternal chemical concentrations were modeled jointly, paternal BPA (RR, 0.77; 95% confidence interval [CI], 0.62-0.95) and mono-isobutyl phthalate (RR, 0.82; 95% CI, 0.67-1.00) were significantly associated with a female excess. Contrarily, maternal BPA (RR, 1.16; 95% CI, 1.03-1.31), mono-isobutyl phthalate (RR, 1.28; 95% CI, 1.06-1.54), mono-benzyl phthalate (RR, 1.31; 95% CI, 1.08-1.58), and mono-n-butyl phthalate (RR, 1.24; 95% CI, 1.01-1.51) were significantly associated with a male excess. These findings underscore varying patterns for the SSR in relation to parental exposures. Given the absence of previous investigation, these partner-specific associations of non-persistent chemicals with the SSR need future corroboration. PMID:25677702

  16. Non-seasonal changes in the intensity of female mate preference and offspring sex ratio in the wild guppy Poecilia reticulata.

    PubMed

    Kudo, Hiromi; Karino, Kenji

    2012-05-01

    It has been demonstrated that the exaggeration of male sexual ornaments and the intensity of female mate preferences of a wild guppy population change over a period of several months. However, the factors that determine the short-term changes in male ornaments and female preferences remained unclear. In this study, we examined the effect of season on these short-term changes by measuring these traits in the same seasons of different years for a wild guppy population in Okinawa, Japan. We also compared the characteristics of the offspring in each collection term, as female guppies are known to have the ability to control offspring characteristics, such as brood size and sex ratios, depending on their mates' attractiveness. Results showed that the total lengths of the males changed seasonally; males in the summer were larger than those in the spring. In contrast, the size of orange spots in males and the intensity of female mating preferences differed in the same seasons of different years. Brood size and offspring body size in each term showed seasonal changes. However, offspring sex ratios exhibited different patterns in the same seasons of different years. Females produced female-biased broods when attractive males with large orange spots were rare. These results suggest that short-term changes in some traits of adult male and female guppies as well as offspring sex ratios may be not determined by seasonal factors, and that these traits may be interrelated. PMID:22559966

  17. Determination of sex from an autopsy sample of adult hyoid bones.

    PubMed

    Mukhopadhyay, Partha Pratim

    2012-07-01

    Determination of sex is the first and crucial step in the process of identifying human remains in forensic casework. Sex determination from skeletal remains is well studied and an extensively documented subject. The hyoid bone, however, has drawn less attention in studies of this nature. The present study was designed to derive a model for the determination of sex from the adult hyoid in a sample of the Indian Bengali population using discriminant function analysis on 50 adult bones (38 men and 12 women). The following discriminant function was obtained: DF = 0.103W + 0.118AP + 0.130CR + 0.483AW + 0.117DR - 20.64. Overall, 90% of the cases could be correctly classified into the two sexes by means of five predictors (overall width, length of the greater cornu, anteroposterior length, width of the body of hyoid and the distance between the lesser cornua) in the model. Cross-validated results showed correct classification in 90% of the cases. The results of this preliminary study show that these variables contribute to discrimination between the two sexes in the study population. Sexing of the adult human hyoid bone is thus possible with reasonable accuracy using the discriminant function on a sample obtained from the same population. PMID:22427484

  18. 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

  19. Population structure and the evolution of sexual size dimorphism and sex ratios in an insular population of Florida box turtles (Terrapene carolina bauri)

    USGS Publications Warehouse

    Dodd, C.K., Jr.

    1997-01-01

    Hypotheses in the chelonian literature suggest that in species with sexual size dimorphism, the smaller sex will mature at a smaller size and a younger age than the larger sex, sex ratios should be biased in favor of the earlier maturing sex, and deviations from a 1:1 sex ratio result from maturation of the smaller sex at a younger age. I tested these hypotheses using data collected from 1991 to 1995 on an insular (Egmont Key) population of Florida box turtles, Terrapene carolina bauri. Contrary to predictions, the earlier maturing sex (males) grew to larger sizes than the late maturing sex. Males were significantly larger than females in mean carapace length but not mean body mass. Sex ratios were not balanced, favoring the earlier maturing sex (1.6 males:1 female), but the sex-ratio imbalance did not result from faster maturation of the smaller sex. The imbalance in the sex ratio in Egmont Key's box turtles is not the result of sampling biases; it may result from nest placement. Size-class structure and sex ratios can provide valuable insights into the status and trends of populations of long-lived turtles.

  20. Estimation of sex from the lower limb measurements of Sudanese adults.

    PubMed

    Ahmed, Altayeb Abdalla

    2013-06-10

    The sex estimation from mutilated and amputated limbs or body parts is one of the most vital steps in person identification in medical-legal autopsies. Sex estimation from lower limb anthropometric measurements has demonstrated a high degree of expected accuracy in a limited range of the global population. The aims of this study were to assess the degree of the sexual dimorphism in lower limb measurements and the accuracy of utilization of these measurements for estimation of sex in a contemporary adult Sudanese population. The tibial length, bimalleolar breadth, foot length, and foot breadth of 240 right-handed Sudanese Arab subjects (120 males and 120 females) aged between 25 and 30 years were measured following international anthropometric standards. Demarking points, sexual dimorphism indices and discriminant functions were developed from 200 subjects (100 males and 100 females) who comprised the study group. All variables were sexually dimorphic. The bimalleolar breadth and foot breadth significantly contributed to sex estimation. Leg dimensions showed a higher accuracy for sex estimation than foot dimensions. Cross-validated sex classification accuracy ranged between 78% and 89.5%. The reliability of these standards was assessed in a test sample of 20 males and 20 females, and the results showed accuracy between 75% and 90%. This study provides new forensic standards for sex estimation from lower limb measurements of Sudanese adults. PMID:23642728

  1. Population structure, sex ratio and growth of the seabob shrimp Xiphopenaeus kroyeri (Decapoda, Penaeidae) from coastal waters of southern Brazil

    PubMed Central

    Grabowski, Raphael Cezar; Simões, Sabrina Morilhas; Castilho, Antonio Leão

    2014-01-01

    Abstract This study evaluated the growth and population structure of Xiphopenaeus kroyeri in Babitonga Bay, southern Brazil. Monthly trawls were conducted from July 2010 through June 2011, using a shrimp boat outfitted with double-rig nets, at depths from 5 to 17 m. Differences from the expected 0.5 sex ratio were determined by applying a Binomial test. A von Bertalanffy growth model was used to estimate the individual growth, and longevity was calculated using its inverted formula. A total of 4,007 individuals were measured, including 1,106 juveniles (sexually immature) and 2,901 adults. Females predominated in the larger size classes. Males and females showed asymptotic lengths of 27.7 mm and 31.4 mm, growth constants of 0.0086 and 0.0070 per day, and longevities of 538 and 661 days, respectively. The predominance of females in larger size classes is the general rule in species of Penaeidae. The paradigm of latitudinal-effect does not appear to apply to seabob shrimp on the southern Brazilian coast, perhaps because of the small proportion of larger individuals, the occurrence of cryptic species, or the intense fishing pressure in this region. The longevity values are within the general range for species of Penaeidae. The higher estimates for longevity in populations at lower latitudes may have occurred because of the growth constants observed at these locations, resulting in overestimation of this parameter. PMID:25561841

  2. Sex ratios and skew models: the special case of evolution of cooperation in polistine wasps.

    PubMed

    Nonacs, Peter

    2002-07-01

    Cooperative breeding often involves reproductive dominance hierarchies. Such hierarchies have been proposed to form and to be maintained through an equitable skew in reproduction for both dominants and subordinates. The general form of skew models also predicts that cooperation can be stable only if cooperation greatly increases group reproductive success or subordinates are greatly constrained in their reproductive prospects relative to dominants. Neither, however, seems to be generally present in the colony initiation phase of temperate polistine wasps, although the behaviors of individuals within such groups are often consistent with skew model predictions. This apparent contradiction can be resolved in the context of a special case of the skew models that incorporate mother-offspring conflicts over sex ratios. Data suggest that all the needed preconditions are present for cooperating foundresses to gain an added benefit through producing male-biased investment ratios. Therefore, the special case model predicts that cooperation can evolve in Hymenoptera with both the observed high skews and reduced per capita group productivity. Further predictions of the special case model (e.g., mixed populations of single and multifoundresses) are also supported. Because the special case model is applicable only to haplodiploids, this may explain why cooperation in vertebrates rarely occurs without significant ecological or physiological constraints. Finally, comparisons to other social Hymenoptera taxa suggest that factors stabilizing cooperation between colony-initiating females may simultaneously constrain the evolution of morphologically specialized worker castes. PMID:18707502

  3. Impact of prenatal technologies on the sex ratio in India: an overview.

    PubMed

    Madan, Kamlesh; Breuning, Martijn H

    2014-06-01

    The fact that techniques of prenatal diagnosis are used in India and China to selectively eliminate females is widely known. It has been extensively reported in the international media and in scientific publications since the 1990s. The publication of the Census of India 2011 shows that the ratio of girls to boys below the age of 6 years continues to decline at an alarming rate. Following that publication, this topic has again received international attention. The aim of this article is to better inform the human genetics community of the magnitude of this practice and its consequences in India.In this overview, we examine the impact of prenatal technology on the sex ratio in India. We present facts and figures from the Census of India and other publications that show that the practice is wide spread throughout India, in urban and rural areas, among the rich and the poor, and among the educated and the illiterate. We also briefly discuss the possible causes, consequences, and solutions. PMID:24177057

  4. Impact of prenatal technologies on the sex ratio in India: an overview

    PubMed Central

    Madan, Kamlesh; Breuning, Martijn H.

    2014-01-01

    The fact that techniques of prenatal diagnosis are used in India and China to selectively eliminate females is widely known. It has been extensively reported in the international media and in scientific publications since the 1990s. The publication of the Census of India 2011 shows that the ratio of girls to boys below the age of 6 years continues to decline at an alarming rate. Following that publication, this topic has again received international attention. The aim of this article is to better inform the human genetics community of the magnitude of this practice and its consequences in India. In this overview, we examine the impact of prenatal technology on the sex ratio in India. We present facts and figures from the Census of India and other publications that show that the practice is wide spread throughout India, in urban and rural areas, among the rich and the poor, and among the educated and the illiterate. We also briefly discuss the possible causes, consequences, and solutions. Genet Med 16 6, 425–432. PMID:24177057

  5. Sheep grazing causes shift in sex ratio and cohort structure of Brandt's vole: Implication of their adaptation to food shortage.

    PubMed

    Li, Guoliang; Hou, Xianglei; Wan, Xinrong; Zhang, Zhibin

    2016-01-01

    Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands, but the causative mechanism of grazing on demographic parameters, particularly the age structure and sex ratio, is rarely investigated. In this study, we examined the effects of sheep grazing on the cohort structure and sex ratio of Brandt's vole (Lasiopodomys brandtii) in Inner Mongolia of China by using large manipulative experimental enclosures during 2010-2013. Our results indicated that sheep grazing significantly decreased the proportion of the spring-born cohort, but increased the proportion of the summer-born cohort. Grazing increased the proportion of males in both spring and summer cohorts. In addition, we found a negative relation between population density and the proportion of the overwinter cohort. Our results suggest that a shift in the cohort structure and the sex ratio may be an important strategy for small rodents to adapt to changes in food resources resulting from livestock grazing. PMID:26331731

  6. Correlates of Unprotected Sex Among Adult Heterosexual Men Living with HIV

    PubMed Central

    Richardson, Jean L.; Espinoza, Lilia; Stoyanoff, Sue

    2006-01-01

    The correlates of unprotected sex among a sample of heterosexual men living with HIV (n = 121) were examined to determine whether patient characteristics can be used as a basis for tailoring safer sex counseling in the clinic setting. Potential correlates of self-reported unprotected oral sex (fellatio) and vaginal sex included participant demographics (e.g., age, ethnicity), disease status (CD4 counts, viral load, years since diagnosis), safer sex beliefs (e.g., condom attitudes), substance use, psychological characteristics (depressive symptoms, dispositional optimism and pessimism), and sex partner characteristics (main/casual partner, HIV status of partner, and duration of relationship). A series of logistic regression analyses were used to determine significant relationships. Correlates of reported levels of prior 3-month unprotected fellatio (24%) and vaginal (21%) sex were not associated with the type of relationship (main or casual) or perceived HIV serostatus of the partner (positive, negative, or unknown). Unprotected fellatio was positively associated with age and CD4 count and inversely associated with optimism and positive condom attitudes (all p's < 0.05). Unprotected vaginal sex was positively associated with duration of relationship and inversely associated with positive condom attitudes. Prevention efforts among sexually active adult heterosexual men living with HIV may benefit from focusing on improving attitudes towards condom use regardless of partner relationship status. PMID:16736114

  7. Sex differences in cognitive trajectories in clinically normal older adults.

    PubMed

    McCarrey, Anna C; An, Yang; Kitner-Triolo, Melissa H; Ferrucci, Luigi; Resnick, Susan M

    2016-03-01

    Age effects on cognitive functioning are well-documented, but effects of sex on trajectories of cognitive aging are less clear. We examined cognitive ability across a variety of measures for 1,065 to 2,127 participants (mean baseline age 64.1 to 69.7 years) from the Baltimore Longitudinal Study of Aging who were repeatedly tested over a mean follow-up interval of 3.0 to 9.0 years with a mean of 2.3 to 4.4 assessments. Memory and other cognitive tests were administered at each visit, assessing mental status, verbal learning and memory, figural memory, language, attention, perceptuomotor speed and integration, executive function, and visuospatial ability. Importantly, participants free from cognitive impairment at all time points were used in the analyses. Results showed that for all tests, higher age at baseline was significantly associated with lower scores, and performance declined over time. In addition, advancing age was associated with accelerated longitudinal declines in performance (trend for mental status). After adjusting for age, education, and race, sex differences were observed across most tests of specific cognitive abilities examined. At baseline, males outperformed females on the 2 tasks of visuospatial ability, and females outperformed males in most other tests of cognition. Sex differences in cognitive change over time indicated steeper rates of decline for men on measures of mental status, perceptuomotor speed and integration, and visuospatial ability, but no measures on which women showed significantly steeper declines. Our results highlight greater resilience to age-related cognitive decline in older women compared with men. PMID:26796792

  8. Auger electron spectroscopy for the determination of sex and age related Ca/P ratio at different bone sites

    SciTech Connect

    Balatsoukas, Ioannis; Kourkoumelis, Nikolaos; Tzaphlidou, Margaret

    2010-10-15

    The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter's Ca/P ratio remains unaffected from all the parameters under study. This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.

  9. Auger electron spectroscopy for the determination of sex and age related Ca/P ratio at different bone sites

    NASA Astrophysics Data System (ADS)

    Balatsoukas, Ioannis; Kourkoumelis, Nikolaos; Tzaphlidou, Margaret

    2010-10-01

    The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter's Ca/P ratio remains unaffected from all the parameters under study. This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.

  10. A cost of Wolbachia-induced sex reversal and female-biased sex ratios: decrease in female fertility after sperm depletion in a terrestrial isopod.

    PubMed

    Rigaud, Thierry; Moreau, Jérôme

    2004-09-22

    A number of parasites are vertically transmitted to new host generations via female eggs. In such cases, host reproduction is an intimate component of parasite fitness and no cost of the infection on host reproduction is expected to evolve. A number of these parasites distort host sex ratios towards females, thereby increasing either parasite fitness or the proportion of the host that transmit the parasite. In terrestrial isopods (woodlice), Wolbachia bacteria are responsible for sex reversion and female-biased sex ratios, changing genetic males into functional neo-females. Although sex ratio distortion is a powerful means for parasites to increase in frequency in host populations, it also has potential consequences on host biology, which may, in turn, have consequences for parasite prevalence. We used the woodlouse Armadillidium vulgare to test whether the interaction between Wolbachia infection and the resulting excess of females would limit female fertility through the reduction in sperm number that they receive from males. We showed that multiple male mating induces sperm depletion, and that this sperm depletion affects fertility only in infected females. This decrease in fertility, associated with male mate choice, may limit the spread of Wolbachia infections in host populations. PMID:15347518

  11. A cost of Wolbachia-induced sex reversal and female-biased sex ratios: decrease in female fertility after sperm depletion in a terrestrial isopod.

    PubMed Central

    Rigaud, Thierry; Moreau, Jérôme

    2004-01-01

    A number of parasites are vertically transmitted to new host generations via female eggs. In such cases, host reproduction is an intimate component of parasite fitness and no cost of the infection on host reproduction is expected to evolve. A number of these parasites distort host sex ratios towards females, thereby increasing either parasite fitness or the proportion of the host that transmit the parasite. In terrestrial isopods (woodlice), Wolbachia bacteria are responsible for sex reversion and female-biased sex ratios, changing genetic males into functional neo-females. Although sex ratio distortion is a powerful means for parasites to increase in frequency in host populations, it also has potential consequences on host biology, which may, in turn, have consequences for parasite prevalence. We used the woodlouse Armadillidium vulgare to test whether the interaction between Wolbachia infection and the resulting excess of females would limit female fertility through the reduction in sperm number that they receive from males. We showed that multiple male mating induces sperm depletion, and that this sperm depletion affects fertility only in infected females. This decrease in fertility, associated with male mate choice, may limit the spread of Wolbachia infections in host populations. PMID:15347518

  12. Past primary sex-ratio estimates of 4 populations of Loggerhead sea turtle based on TSP durations.

    NASA Astrophysics Data System (ADS)

    Monsinjon, Jonathan; Kaska, Yakup; Tucker, Tony; LeBlanc, Anne Marie; Williams, Kristina; Rostal, David; Girondot, Marc

    2016-04-01

    Ectothermic species are supposed to be strongly affected by climate change and particularly those that exhibit temperature-dependent sex-determination (TSD). Actually, predicting the embryonic response of such organism to incubation-temperature variations in natural conditions remains challenging. In order to assess the vulnerability of sea turtles, primary sex-ratio estimates should be produced at pertinent ecological time and spatial scales. Although information on this important demographic parameter is one of the priorities for conservation purpose, accurate methodology to produce such an estimate is still lacking. The most commonly used method invocates incubation duration as a proxy for sex-ratio. This method is inappropriate because temperature influences incubation duration during all development whereas sex is influenced by temperature during only part of development. The thermosensitive period of development for sex determination (TSP) lies in the middle third of development. A model of embryonic growth must be used to define precisely the position of the TSP at non-constant incubation temperatures. The thermal reaction norm for embryonic growth rate have been estimated for 4 distinct populations of the globally distributed and threatened marine turtle Caretta caretta. A thermal reaction norm describes the pattern of phenotypic expression of a single genotype across a range of temperatures. Moreover, incubation temperatures have been reconstructed for the last 35 years using a multi-correlative model with climate temperature. After development of embryos have been modelled, we estimated the primary sex-ratio based on the duration of the TSP. Our results suggests that Loggerhead sea turtles nesting phenology is linked with the period within which both sexes can be produced in variable proportions. Several hypotheses will be discussed to explain why Caretta caretta could be more resilient to climate change than generally thought for sex determination.

  13. Disparities in Health and Disability Among Older Adults in Same-Sex Cohabiting Relationships

    PubMed Central

    Gonzales, Gilbert; Henning-Smith, Carrie

    2014-01-01

    Objectives The present study compared indicators of impaired health and disability between older adults in same-sex cohabiting relationships and their peers in opposite-sex cohabiting relationships. Methods Data were obtained on men (n=698) and women (n=630) aged 50 years and older and in self-reported same-sex relationships from the National Health Interview Survey. Multiple regression analyses were conducted to estimate differences in physical health, mental health and disability status. Results Compared to their peers in married opposite-sex relationships, older men in same-sex relationships exhibited greater odds of psychological distress, and older women in same-sex relationships experienced elevated odds of poor/fair health, needing help with ADLs and IADLs, functional limitations, and psychological distress. Discussion This study adds to the limited information on health and disability among older lesbian, gay and bisexual adults. As this population grows, gerontologists must develop a better understanding of the unique issues and challenges facing them and their families. PMID:25253727

  14. Couples' urinary concentrations of benzophenone-type ultraviolet filters and the secondary sex ratio.

    PubMed

    Bae, Jisuk; Kim, Sungduk; Kannan, Kurunthachalam; Buck Louis, Germaine M

    2016-02-01

    The secondary sex ratio (SSR), defined as the ratio of males to females at birth, has been investigated in relation to endocrine disruptors to search for environmental toxicants perturbing human sex selection. Benzophenone (BP)-type ultraviolet (UV) filters, which are used in sunscreens and personal care products, have been reported to exert estrogenic and anti-androgenic activities. This study aimed to evaluate the association between maternal, paternal, and couple urinary concentrations of BP-type UV filters and the SSR, given the absence of previous investigation. The study cohort comprised 220 couples who were enrolled in the Longitudinal Investigation of Fertility and the Environment (LIFE) Study between 2005 and 2009 prior to conception and who had a singleton birth during the follow-up period. Couples' urinary concentrations of five BP-type UV filters (ng/mL) were measured using triple-quadrupole tandem mass spectrometry: 2,4-dihydroxybenzophenone (BP-1), 2,2',4,4'-tetrahydroxybenzophenone (BP-2), 2-hydroxy-4-methoxybenzophenone (BP-3), 2,2'-dihydroxy-4-methoxybenzophenone (BP-8), and 4-hydroxybenzophenone (4-OH-BP). Modified Poisson regression models were used to estimate the relative risks (RRs) of a male birth for each BP-type UV filter, after adjusting for potential confounders. When maternal and paternal urinary BP-type UV filter concentrations were modeled jointly, both maternal BP-2 (2nd vs 1st tertile, RR, 0.62, 95% confidence interval [CI], 0.43-0.91) and paternal BP-2 (3rd vs 1st tertile, RR, 0.67, 95% CI, 0.45-0.99; p-trend, 0.04) were significantly associated with an excess of female births. Contrarily, maternal 4-OH-BP was significantly associated with an excess of male births (2nd vs 1st tertile, RR, 1.87, 95% CI, 1.27-2.74; 3rd vs 1st tertile, RR, 1.80, 95% CI, 1.13-2.87; p-trend, 0.02). Our findings provide the first evidence suggesting that BP-type UV filters may affect the SSR. However, future corroboration is needed, given the exploratory

  15. The Individual with Intellectual Disabilities and Sex Education: Perspectives of Involved Adults.

    ERIC Educational Resources Information Center

    Brown, Randel D.

    This study examined the perceptions of involved adults concerning sex education for individuals with intellectual disabilities. Participants were 40 individuals who provided direct care or instruction to individuals with intellectual disabilities or who had administrative responsibility for them. They completed a 36-item Q-sort that examined their…

  16. Race-Sex Differences in Job Quality Returns Attributed to Education among Young Rural Adults.

    ERIC Educational Resources Information Center

    Eggers, Judi L.; Dunkelberger, John E.

    Using the general hypothesis that job quality returns to education are positive for all employment indicators among race and sex groupings, a sample of young adults originally from southern rural areas and small towns was queried concerning the status ranking of their current occupation, income earned, supervisory responsibility, and extent of…

  17. Sex Role Strain Among Kibbutz Adolescents and Adults: A Developmental Perspective.

    ERIC Educational Resources Information Center

    Snarey, John; And Others

    1986-01-01

    It was hypothesized that adolescent females experience greater sex role strain than other kibbutz members. Loevinger's ego development test was administered to 40 kibbutz members. The findings supported the hypothesis and showed that adult women are significantly more likely to focus their dissatisfaction in the area of actual role behavior. (JAZ)

  18. Adolescent and Young Adult Male Sex Offenders: Understanding the Role of Recidivism

    ERIC Educational Resources Information Center

    Riser, Diana K.; Pegram, Sheri E.; Farley, Julee P.

    2013-01-01

    The current review explores the complex paths that can lead to adolescent and young adult males becoming sexually abusive. Because sexual abuse is an ongoing issue in our society that is often oversimplified, this article distinguishes between the various risk factors that predict sexually abusive behavior and types of sex offenders, particularly…

  19. Adult Development and Life Satisfaction Functions of Sex, Marital Status and Age.

    ERIC Educational Resources Information Center

    Coles, Claire; McCall, Fran

    Quality of life in adulthood (ages 27-47) was investigated; age, marital status and sex were considered the primary variables. Attention was given to the consideration of the current crises-oriented theory of adult development. The interrelationship of the variables was of principle interest in assessing life satisfaction and personality…

  20. Untreated ADHD in Adults: Are There Sex Differences in Symptoms, Comorbidity, and Impairment?

    ERIC Educational Resources Information Center

    Rasmussen, Kirsten; Levander, Sten

    2009-01-01

    Objective: To analyze sex differences among adult, never-treated patients referred for central stimulant treatment of ADHD. Method: Data for 600 consecutive patients from northern Norway referred for evaluation by an expert team during 7 years were analyzed. General background information, diagnostic and social history, and symptom profiles were…

  1. Effects of larval-juvenile treatment with perchlorate and co-treatment with thyroxine on zebrafish sex ratios

    USGS Publications Warehouse

    Mukhi, S.; Torres, L.; Patino, R.

    2007-01-01

    The objective of this study was to determine the effect of larval-juvenile exposure to perchlorate, a thyroid hormone synthesis inhibitor, on the establishment of gonadal sex ratios in zebrafish. Zebrafish were exposed to untreated water or water containing perchlorate at 100 or 250 ppm for a period of 30 days starting at 3 days postfertilization (dpf). Recovery treatments consisted of a combination of perchlorate and exogenous thyroxine (T4; 10 nM). Thyroid histology was assessed at the end of the treatment period (33 dpf), and gonadal histology and sex ratios were determined in fish that were allowed an additional 10-day period of growth in untreated water. As expected, exposure to perchlorate caused changes in thyroid histology consistent with hypothyroidism and these effects were reversed by co-treatment with exogenous T4. Perchlorate did not affect fish survival but co-treatment with T4 induced higher mortality. However, relative to the corresponding perchlorate concentration, co-treatment with T4 caused increased mortality only at a perchlorate concentration of 100 ppm. Perchlorate alone or in the presence of T4 suppressed body length at 43 dpf relative to control values. Perchlorate exposure skewed the sex ratio toward female in a concentration-dependent manner, and co-treatment with T4 not only blocked the feminizing effect of perchlorate but also overcompensated by skewing the sex ratio towards male. Moreover, co-treatment with T4 advanced the onset of spermatogenesis in males. There was no clear association between sex ratios and larval survival or growth. We conclude that endogenous thyroid hormone plays a role in the establishment of gonadal sex phenotype during early development in zebrafish. ?? 2006 Elsevier Inc. All rights reserved.

  2. Sex ratio at birth in twenty-first century Greece: the role of ethnic and social groups.

    PubMed

    Gavalas, V; Rontos, K; Nagopoulos, N

    2015-05-01

    The number of male per 100 female live births (defined as the sex ratio at birth, SRB) has been shown to be consistently stable in human populations irrespective of time and geographical location. All over the globe approximately 105 boys are born for every 100 girls and any significant deviation from this 'global average' is considered to be unnatural and is attributed to sex-selective under-reporting of births, sex-selective abortion, sex-selective infanticide or other man-made factors. The present paper uses data on civil registration from 2004-2011 to investigate the sex ratio at birth in modern Greece. It was found that the SRB is extremely masculine when the parents originate from the Indian sub-continent and China. The SRB is also unnaturally high (more than 113 boys per 100 girls) in the case of legitimate births born to Greek mothers who are illiterate. These findings are strong evidence that sex-selective abortions are taking place in Greece within population groups with a certain ethnic and social profile. Other parameters, such as age of mother at birth, birth order, legal status of birth and geographical location, were also investigated and they were found to play a role in the variation of SRB, but not to the extent education and ethnic group do. PMID:24849079

  3. TBBPA chronic exposure produces sex-specific neurobehavioral and social interaction changes in adult zebrafish.

    PubMed

    Chen, Jiangfei; Tanguay, Robert L; Simonich, Michael; Nie, Shangfei; Zhao, Yuxin; Li, Lelin; Bai, Chenglian; Dong, Qiaoxiang; Huang, Changjiang; Lin, Kuangfei

    2016-01-01

    The toxicity of tetrabromobisphenol A (TBBPA) has been extensively studied because of its high production volume. TBBPA is toxic to aquatic fish based on acute high concentration exposure tests, and few studies have assessed the behavioral effects of low concentration chronic TBBPA exposures in aquatic organisms. The present study defined the developmental and neurobehavioral effects associated with exposure of zebrafish to 0, 5 and 50nM TBBPA during 1-120days post-fertilization (dpf) following by detoxification for four months before the behaviors assessment. These low concentration TBBPA exposures were not associated with malformations and did not alter sex ratio, but resulted in reduced zebrafish body weight and length. Adult behavioral assays indicated that TBBPA exposed males had significantly higher average swim speeds and spent significantly more time in high speed darting mode and less time in medium cruising mode compared to control males. In an adult photomotor response assay, TBBPA exposure was associated with hyperactivity in male fish. Female zebrafish responses in these assays followed a similar trend, but the magnitude of TBBPA effects was generally smaller than in males. Social interaction evaluated using a mirror attack test showed that 50nM TBBPA exposed males had heightened aggression. Females exposed to 50nM TBBPA spent more time in the vicinity of the mirror, but did not show increased aggression toward the mirror compared to unexposed control fish. Overall, the hyperactivity and social behavior deficits ascribed here to chronic TBBPA exposure was most profound in males. Our findings indicate that TBBPA can cause developmental and neurobehavioral deficits, and may pose significant health risk to humans. PMID:27221227

  4. The influence of operational sex ratio on the intensity of competition for mates.

    PubMed

    Weir, Laura K; Grant, James W A; Hutchings, Jeffrey A

    2011-02-01

    The evolution and maintenance of secondary sexual characteristics and behavior are heavily influenced by the variance in mating success among individuals in a population. The operational sex ratio (OSR) is often used as a predictor of the intensity of competition for mates, as it describes the relative number of males and females who are ready to mate. We investigate changes in aggression, courtship, mate guarding, and sperm release as a function of changes in the OSR using meta-analytic techniques. As the OSR becomes increasingly biased, aggression increases as competitors attempt to defend mates, but this aggression begins to decrease at an OSR of 1.99, presumably due to the increased costs of competition as rivals become more numerous. Sperm release follows a similar but not significant trend. By contrast, courtship rate decreases as the OSR becomes increasingly biased, whereas mate guarding and copulation duration increase. Overall, predictable behavioral changes occur in response to OSR, although the nature of the change is dependent on the type of mating behavior. These results suggest considerable flexibility of mating system structure within species, which can be predicted by OSR and likely results in variation in the strength of sexual selection. PMID:21460553

  5. Changes in Income at Macro Level Predict Sex Ratio at Birth in OECD Countries

    PubMed Central

    2016-01-01

    The human sex ratio at birth (SRB) is approximately 107 boys for every 100 girls. SRB was rising until the World War II and has been declining slightly after the 1950s in several industrial countries. Recent studies have shown that SRB varies according to exposure to disasters and socioeconomic conditions. However, it remains unknown whether changes in SRB can be explained by observable macro-level socioeconomic variables across multiple years and countries. Here we show that changes in disposable income at the macro level positively predict SRB in OECD countries. A one standard deviation increase in the change of disposable income is associated with an increase of 1.03 male births per 1000 female births. The relationship is possibly nonlinear and driven by extreme changes. The association varies from country to country being particular strong in Estonia. This is the first evidence to show that economic and social conditions are connected to SRB across countries at the macro level. This calls for further research on the effects of societal conditions on general characteristics at birth. PMID:27437701

  6. Evidence of Hermaphroditism and Sex Ratio Distortion in the Fungal Feeding Nematode Bursaphelenchus okinawaensis

    PubMed Central

    Shinya, Ryoji; Hasegawa, Koichi; Chen, Anthony; Kanzaki, Natsumi; Sternberg, Paul W.

    2014-01-01

    Nematodes have many different reproductive strategies along with their divergent life histories; the ability of hermaphrodite to self- and cross-fertilize is useful for genetic manipulation. Here, we demonstrate the hermaphroditism of the fungal feeding nematode Bursaphelenchus okinawaensis, which was formerly described as a parthenogenetic nematode, and we show its other unique sexual characteristics. To determine that it is hermaphroditic, we performed the following experiments: observation of the pronuclear and chromosome behavior during oogenesis and early embryogenesis; observation of spermatogenesis during the fourth larval stage; investigation of sperm utilization; and investigation of phenotypic segregation after cross-mating using a chemically induced visible mutant. We then investigated the mating preferences and spermatid size difference between males and hermaphrodites. B. okinawaensis males successfully mated only with sperm-depleted old hermaphrodites, and the spermatid sizes of males were almost the same as those of hermaphrodites. Moreover, the sex ratio of cross-fertilized progeny was highly skewed toward hermaphrodites. B. okinawaensis is phylogenetically distant from established model nematodes such as C. elegans and is more closely related to some economically relevant parasitic nematodes. This newly discovered hermaphroditic nematode has great potential for evolutionary and parasitological research. PMID:25122669

  7. Changes in Income at Macro Level Predict Sex Ratio at Birth in OECD Countries.

    PubMed

    Kanninen, Ohto; Karhula, Aleksi

    2016-01-01

    The human sex ratio at birth (SRB) is approximately 107 boys for every 100 girls. SRB was rising until the World War II and has been declining slightly after the 1950s in several industrial countries. Recent studies have shown that SRB varies according to exposure to disasters and socioeconomic conditions. However, it remains unknown whether changes in SRB can be explained by observable macro-level socioeconomic variables across multiple years and countries. Here we show that changes in disposable income at the macro level positively predict SRB in OECD countries. A one standard deviation increase in the change of disposable income is associated with an increase of 1.03 male births per 1000 female births. The relationship is possibly nonlinear and driven by extreme changes. The association varies from country to country being particular strong in Estonia. This is the first evidence to show that economic and social conditions are connected to SRB across countries at the macro level. This calls for further research on the effects of societal conditions on general characteristics at birth. PMID:27437701

  8. CHRONIC ZEBRAFISH PFOS EXPOSURE ALTERS SEX RATIO AND MATERNAL RELATED EFFECTS IN F1 OFFSPRING

    PubMed Central

    Wang, Mingyong; Chen, Jiangfei; Lin, Kuanfei; Chen, Yuanhong; Hu, Wei; Tanguay, Robert L.; Huang, Changjiang; Dong, Qiaoxiang

    2012-01-01

    Perfluorooctanesulfonic acid (PFOS) is an organic contaminant ubiquitous in the environment, wildlife, and humans. Few studies have assessed its chronic toxicity on aquatic organisms. The present study defined the effects of long-term exposure to PFOS on zebrafish development and reproduction. Specifically, zebrafish at 8 h postfertilization (hpf) were exposed to PFOS at 0, 5, 50, and 250 μg/L for five months. Growth suppression was observed in the 250 μg/L PFOS-treated group. The sex ratio was altered, with a significant female dominance in the high-dose PFOS group. Male gonad development was also impaired in a dose-dependent manner by PFOS exposure. Although female fecundity was not impacted, the F1 embryos derived from high-dose exposed females paired with males without PFOS exposure developed severe deformity at early development stages and resulted in 100% larval mortality at 7 d postfertilization (dpf). Perfluorooctanesulfonic acid quantification in embryos indicated that decreased larval survival in F1 offspring was directly correlated to the PFOS body burden, and larval lethality was attributable to maternal transfer of PFOS to the eggs. Lower-dose parental PFOS exposure did not result in decreased F1 survival; however, the offspring displayed hyperactivity of basal swimming speed in a light-to-dark behavior assessment test. These findings demonstrate that chronic exposure to PFOS adversely impacts embryonic growth, reproduction, and subsequent offspring development. Environ. PMID:21671259

  9. Second to fourth digit ratio: A predictor of adult lung function

    PubMed Central

    Park, I-Nae; Yum, Ho-Kee; Lee, Sang Chul; Oh, Jin Kyu; Kim, Tae Beom

    2014-01-01

    Sex and sex hormones play a major role in lung physiology. It has been proposed that the ratio of the second to fourth digits (digit ratio) is correlated with fetal sex hormones. We therefore hypothesized that digit ratio might help predict lung function. We investigated the relationship between digit ratio and pulmonary function test (PFT) findings. A total of 245 South Korean patients (162 male, 83 female) aged from 34 to 90 years who were hospitalized for urological surgery were prospectively enrolled. Before administering the PFTs, the lengths of the second and fourth digits of the right hand were measured by a single investigator using a digital Vernier caliper. In males (n = 162), univariate and multivariate analysis using linear regression models showed that digit ratio was a significant predictive factor of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) (FVC: r = 0.156, P = 0.047; FEV1: r = 0.160, P = 0.042). In male ever-smokers (n = 69), lung functions (FVC and FEV1) were correlated with smoking exposure rather than digit ratio. In female never-smokers (n = 83), lung functions (FEV1 and FEV1/FVC ratio) were positively correlated with digit ratio on univariate analysis (FEV1: r = 0.242, P = 0.027; FEV1/FVC ratio: r = 0.245, P = 0.026). Patients with lower digit ratios tend to have decreased lung function. These results suggest that digit ratio is a predictor of airway function. PMID:24369148

  10. Can Sibling Sex Ratios Be Used as a Valid Test for the Prenatal Androgen Hypothesis of Autism Spectrum Disorders?

    PubMed Central

    Cheslack-Postava, Keely; Susser, Ezra; Liu, Kayuet; Bearman, Peter S.

    2015-01-01

    Background Sibling sex ratios have been applied as an indirect test of a hypothesized association between prenatal testosterone levels and risk for autism, a developmental disorder disproportionately affecting males. Differences in sibling sex ratios between those with and without autism would provide evidence of a shared risk factor for autism and offspring sex. Conclusions related to prenatal testosterone, however, require additional assumptions. Here, we used directed acyclic graphs (DAGs) to clarify the elements required for a valid test of the hypothesis that sibling sex ratios differ between children with and without autism. We then conducted such a test using a large, population-based sample of children. Methods Over 1.1 million subjects, born in California from 1992–2007, and identified through birth records, were included. The association between autism diagnosis, determined using the administrative database of the California Department of Developmental Services, and the sex of the subsequent sibling was examined using generalized estimating equations. Sources of potential bias identified using DAGs were addressed. Results Among male children with autism, 52.2% of next-born siblings were brothers, versus 51.0% for unaffected males. For females with autism, 50.2% of following siblings were brothers versus 51.2% among control females. The relative risk of a subsequent male sibling associated with autism diagnosis was 1.02 (95% confidence interval: 0.99, 1.04). Conclusions In a large, population-based sample we failed to find evidence suggesting an excess of brothers among children with autism while controlling for several threats to validity. This test cannot rule out a role of any given exposure, including prenatal testosterone, in either risk of autism or offspring sex ratio, but suggests against a common cause of both. PMID:26495967

  11. Status Hierarchy, Attractiveness Hierarchy and Sex Ratio: Three Contextual Factors Explaining the Status-Aggression Link among Adolescents

    ERIC Educational Resources Information Center

    Zwaan, Michiel; Dijkstra, Jan Kornelis; Veenstra, Rene

    2013-01-01

    The moderating effects of three specific conditions (status hierarchy, attractiveness hierarchy and sex ratio) on the link between status (popularity) and physical and relational aggression were examined in a large sample of adolescent boys ("N" = 1,665) and girls ("N" = 1,637) ("M" age = 13.60). In line with the…

  12. ASSSOCIATION BETWEEN LOCI WITH DELETERIOUS ALLELES AND DISTORTED SEX RATIOS IN AN INBRED LINE OF TILAPIA (OREOCHOMIS AUREUS)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three microsatellite markers (UNH159, UNH231, and UNH216) were examined for association with both deleterious genes and sex ratio distortions in a full-sib family of 222 progeny from the fourth generation of a meiogynogenetic tilapia line (Oreochromis aureus). The three markers previously were mappe...

  13. Cancer, Infant Mortality and Birth Sex-Ratio in Fallujah, Iraq 2005–2009

    PubMed Central

    Busby, Chris; Hamdan, Malak; Ariabi, Entesar

    2010-01-01

    There have been anecdotal reports of increases in birth defects and cancer in Fallujah, Iraq blamed on the use of novel weapons (possibly including depleted uranium) in heavy fighting which occurred in that town between US led forces and local elements in 2004. In Jan/Feb 2010 the authors organised a team of researchers who visited 711 houses in Fallujah, Iraq and obtained responses to a questionnaire in Arabic on cancer, birth defects and infant mortality. The total population in the resulting sample was 4,843 persons with and overall response rate was better than 60%. Relative Risks for cancer were age-standardised and compared to rates in the Middle East Cancer Registry (MECC, Garbiah Egypt) for 1999 and rates in Jordan 1996–2001. Between Jan 2005 and the survey end date there were 62 cases of cancer malignancy reported (RR = 4.22; CI: 2.8, 6.6; p < 0.00000001) including 16 cases of childhood cancer 0–14 (RR = 12.6; CI: 4.9, 32; p < 0.00000001). Highest risks were found in all-leukaemia in the age groups 0–34 (20 cases RR = 38.5; CI: 19.2, 77; p < 0.00000001), all lymphoma 0–34 (8 cases, RR = 9.24;CI: 4.12, 20.8; p < 0.00000001), female breast cancer 0–44 (12 cases RR = 9.7;CI: 3.6, 25.6; p < 0.00000001) and brain tumours all ages (4 cases, RR = 7.4;CI: 2.4, 23.1; P < 0.004). Infant mortality was based on the mean birth rate over the 4 year period 2006–2009 with 1/6th added for cases reported in January and February 2010. There were 34 deaths in the age group 0–1 in this period giving a rate of 80 deaths per 1,000 births. This may be compared with a rate of 19.8 in Egypt (RR = 4.2 p < 0.00001) 17 in Jordan in 2008 and 9.7 in Kuwait in 2008. The mean birth sex-ratio in the recent 5-year cohort was anomalous. Normally the sex ratio in human populations is a constant with 1,050 boys born to 1,000 girls. This is disturbed if there is a genetic damage stress. The ratio of boys to 1,000 girls in the 0–4, 5–9, 10–14 and 15–19 age cohorts in the

  14. Cancer, infant mortality and birth sex-ratio in Fallujah, Iraq 2005-2009.

    PubMed

    Busby, Chris; Hamdan, Malak; Ariabi, Entesar

    2010-07-01

    There have been anecdotal reports of increases in birth defects and cancer in Fallujah, Iraq blamed on the use of novel weapons (possibly including depleted uranium) in heavy fighting which occurred in that town between US led forces and local elements in 2004. In Jan/Feb 2010 the authors organised a team of researchers who visited 711 houses in Fallujah, Iraq and obtained responses to a questionnaire in Arabic on cancer, birth defects and infant mortality. The total population in the resulting sample was 4,843 persons with and overall response rate was better than 60%. Relative Risks for cancer were age-standardised and compared to rates in the Middle East Cancer Registry (MECC, Garbiah Egypt) for 1999 and rates in Jordan 1996-2001. Between Jan 2005 and the survey end date there were 62 cases of cancer malignancy reported (RR = 4.22; CI: 2.8, 6.6; p < 0.00000001) including 16 cases of childhood cancer 0-14 (RR = 12.6; CI: 4.9, 32; p < 0.00000001). Highest risks were found in all-leukaemia in the age groups 0-34 (20 cases RR = 38.5; CI: 19.2, 77; p < 0.00000001), all lymphoma 0-34 (8 cases, RR = 9.24;CI: 4.12, 20.8; p < 0.00000001), female breast cancer 0-44 (12 cases RR = 9.7;CI: 3.6, 25.6; p < 0.00000001) and brain tumours all ages (4 cases, RR = 7.4;CI: 2.4, 23.1; P < 0.004). Infant mortality was based on the mean birth rate over the 4 year period 2006-2009 with 1/6th added for cases reported in January and February 2010. There were 34 deaths in the age group 0-1 in this period giving a rate of 80 deaths per 1,000 births. This may be compared with a rate of 19.8 in Egypt (RR = 4.2 p < 0.00001) 17 in Jordan in 2008 and 9.7 in Kuwait in 2008. The mean birth sex-ratio in the recent 5-year cohort was anomalous. Normally the sex ratio in human populations is a constant with 1,050 boys born to 1,000 girls. This is disturbed if there is a genetic damage stress. The ratio of boys to 1,000 girls in the 0-4, 5-9, 10-14 and 15-19 age cohorts in the Fallujah sample were 860

  15. Peripheral coding of sex pheromone blends with reverse ratios in two helicoverpa species.

    PubMed

    Wu, Han; Hou, Chao; Huang, Ling-Qiao; Yan, Fu-Shun; Wang, Chen-Zhu

    2013-01-01

    The relative proportions of components in a pheromone blend play a major role in sexual recognition in moths. Two sympatric species, Helicoverpa armigera and Helicoverpa assulta, use (Z)-11-hexadecenal (Z11-16: Ald) and (Z)-9-hexadecenal (Z9-16: Ald) as essential sex pheromone components but in very different ratios, 97∶3 and 7∶93 respectively. Using wind tunnel tests, single sensillum recording and in vivo calcium imaging, we comparatively studied behavioral responses and physiological activities at the level of antennal sensilla and antennal lobe (AL) in males of the two species to blends of the two pheromone components in different ratios (100∶0, 97∶3, 50∶50, 7∶93, 0∶100). Z11-16: Ald and Z9-16: Ald were recognized by two populations of olfactory sensory neurons (OSNs) in different trichoid sensilla on antennae of both species. The ratios of OSNs responding to Z11-16:Ald and Z9-16:Ald OSNs were 100∶28.9 and 21.9∶100 in H. armigera and H. assulta, respectively. The Z11-16:Ald OSNs in H. armigera exhibited higher sensitivity and efficacy than those in H. assulta, while the Z9-16:Ald OSNs in H. armigera had the same sensitivity but lower efficacy than those in H. assulta. At the dosage of 10 µg, Z11-16: Ald and Z9-16: Ald evoked calcium activity in 8.5% and 3.0% of the AL surface in H. armigera, while 5.4% and 8.6% of AL in H. assulta, respectively. The calcium activities in the AL reflected the peripheral input signals of the binary pheromone mixtures and correlated with the behavioral output. These results demonstrate that the binary pheromone blends were precisely coded by the firing frequency of individual OSNs tuned to Z11-16: Ald or Z9-16: Ald, as well as their population sizes. Such information was then accurately reported to ALs of H. armigera and H. assulta, eventually producing different behaviors. PMID:23894593

  16. Peripheral Coding of Sex Pheromone Blends with Reverse Ratios in Two Helicoverpa Species

    PubMed Central

    Huang, Ling-Qiao; Yan, Fu-Shun; Wang, Chen-Zhu

    2013-01-01

    The relative proportions of components in a pheromone blend play a major role in sexual recognition in moths. Two sympatric species, Helicoverpa armigera and Helicoverpa assulta, use (Z)-11-hexadecenal (Z11–16: Ald) and (Z)-9-hexadecenal (Z9–16: Ald) as essential sex pheromone components but in very different ratios, 97∶3 and 7∶93 respectively. Using wind tunnel tests, single sensillum recording and in vivo calcium imaging, we comparatively studied behavioral responses and physiological activities at the level of antennal sensilla and antennal lobe (AL) in males of the two species to blends of the two pheromone components in different ratios (100∶0, 97∶3, 50∶50, 7∶93, 0∶100). Z11–16: Ald and Z9–16: Ald were recognized by two populations of olfactory sensory neurons (OSNs) in different trichoid sensilla on antennae of both species. The ratios of OSNs responding to Z11–16:Ald and Z9–16:Ald OSNs were 100∶28.9 and 21.9∶100 in H. armigera and H. assulta, respectively. The Z11–16:Ald OSNs in H. armigera exhibited higher sensitivity and efficacy than those in H. assulta, while the Z9–16:Ald OSNs in H. armigera had the same sensitivity but lower efficacy than those in H. assulta. At the dosage of 10 µg, Z11–16: Ald and Z9–16: Ald evoked calcium activity in 8.5% and 3.0% of the AL surface in H. armigera, while 5.4% and 8.6% of AL in H. assulta, respectively. The calcium activities in the AL reflected the peripheral input signals of the binary pheromone mixtures and correlated with the behavioral output. These results demonstrate that the binary pheromone blends were precisely coded by the firing frequency of individual OSNs tuned to Z11–16: Ald or Z9–16: Ald, as well as their population sizes. Such information was then accurately reported to ALs of H. armigera and H. assulta, eventually producing different behaviors. PMID:23894593

  17. Risky business: Is there an association between casual sex and mental health among emerging adults?

    PubMed

    Bersamin, Melina M; Zamboanga, Byron L; Schwartz, Seth J; Donnellan, M Brent; Hudson, Monika; Weisskirch, Robert S; Kim, Su Yeong; Agocha, V Bede; Whitbourne, Susan Krauss; Caraway, S Jean

    2014-01-01

    A multiethnic sample of single, heterosexual, emerging-adult college students (N = 3,907) ages 18 to 25, from 30 institutions across the United States, participated in a study about identity, culture, psychological well-being, and risky behaviors. Given ongoing debates about the connection between casual sex and psychological adjustment, in the current study we assessed the cross-sectional association of participation in casual sex with psychological well-being and distress. A greater proportion of men (18.6%) compared to women (7.4%) reported having had casual sex in the month prior to assessment. Structural equation modeling indicated that casual sex was negatively associated with well-being (ß = .20, p < .001) and positively associated with psychological distress (ß = .16, p < .001). Gender did not moderate these associations. For emerging-adult college students, engaging in casual sex may elevate risk for negative psychological outcomes. PMID:23742031

  18. Variance in age-specific sex composition of Pacific halibut catches, and comparison of statistical and genetic methods for reconstructing sex ratios

    NASA Astrophysics Data System (ADS)

    Loher, Timothy; Woods, Monica A.; Jimenez-Hidalgo, Isadora; Hauser, Lorenz

    2016-01-01

    Declines in size at age of Pacific halibut Hippoglossus stenolepis, in concert with sexually-dimorphic growth and a constant minimum commercial size limit, have led to the expectation that the sex composition of commercial catches should be increasingly female-biased. Sensitivity analyses suggest that variance in sex composition of landings may be the most influential source of uncertainty affecting current understanding of spawning stock biomass. However, there is no reliable way to determine sex at landing because all halibut are eviscerated at sea. In 2014, a statistical method based on survey data was developed to estimate the probability that fish of any given length at age (LAA) would be female, derived from the fundamental observation that large, young fish are likely female whereas small, old fish have a high probability of being male. Here, we examine variability in age-specific sex composition using at-sea commercial and closed-season survey catches, and compare the accuracy of the survey-based LAA technique to genetic markers for reconstructing the sex composition of catches. Sexing by LAA performed best for summer-collected samples, consistent with the hypothesis that the ability to characterize catches can be influenced by seasonal demographic shifts. Additionally, differences between survey and commercial selectivity that allow fishers to harvest larger fish within cohorts may generate important mismatch between survey and commercial datasets. Length-at-age-based estimates ranged from 4.7% underestimation of female proportion to 12.0% overestimation, with mean error of 5.8 ± 1.5%. Ratios determined by genetics were closer to true sample proportions and displayed less variability; estimation to within < 1% of true ratios was limited to genetics. Genetic estimation of female proportions ranged from 4.9% underestimation to 2.5% overestimation, with a mean absolute error of 1.2 ± 1.2%. Males were generally more difficult to assign than females: 6.7% of

  19. Sexing adult black-legged kittiwakes by DNA behavior, and morphology

    USGS Publications Warehouse

    Jodice, P.G.R.; Lanctot, Richard B.; Gill, V.A.; Roby, D.D.; Hatch, Shyla A.

    2000-01-01

    We sexed adult Black-legged Kittiwakes (Rissa tridactyla) using DNA-based genetic techniques, behavior and morphology and compared results from these techniques. Genetic and morphology data were collected on 605 breeding kittiwakes and sex-specific behaviors were recorded for a sub-sample of 285 of these individuals. We compared sex classification based on both genetic and behavioral techniques for this sub-sample to assess the accuracy of the genetic technique. DNA-based techniques correctly sexed 97.2% and sex-specific behaviors, 96.5% of this sub-sample. We used the corrected genetic classifications from this sub-sample and the genetic classifications for the remaining birds, under the assumption they were correct, to develop predictive morphometric discriminant function models for all 605 birds. These models accurately predicted the sex of 73-96% of individuals examined, depending on the sample of birds used and the characters included. The most accurate single measurement for determining sex was length of head plus bill, which correctly classified 88% of individuals tested. When both members of a pair were measured, classification levels improved and approached the accuracy of both behavioral observations and genetic analyses. Morphometric techniques were only slightly less accurate than genetic techniques but were easier to implement in the field and less costly. Behavioral observations, while highly accurate, required that birds be easily observable during the breeding season and that birds be identifiable. As such, sex-specific behaviors may best be applied as a confirmation of sex for previously marked birds. All three techniques thus have the potential to be highly accurate, and the selection of one or more will depend on the circumstances of any particular field study. Received 2 February 2000, accepted 1 April 2000.

  20. Marriage season, promptness of successful pregnancy and first-born sex ratio in a historical natural fertility population - evidence for sex-dependent early pregnancy loss?

    NASA Astrophysics Data System (ADS)

    Nonaka, K.; Desjardins, Bertrand; Charbonneau, Hubert; Légaré, Jacques; Miura, Teiji

    We investigated population-based vital records of the seventeenth and eighteenth century French Canadian population to assess the effects of marriage season on the outcome of the first births under natural fertility conditions (n=21,698 marriages). Promptness of the first successful conception after marriage differed according to marriage season; the proportion of marriages with a marriage-first birth interval of 8.0-10.0 months was lowest (34%) for marriages in August-October (P=0.001). Although the male/female sex ratio of the babies born with an interval of 8.0-10.0 months was generally higher (1.10) than those with an interval of 10.0-24.0 months (1.05), the marriages in August-October resulted in a significantly reduced sex ratio (0.96) among only the prompt conceptions (P=0.026). We discuss whether this seasonal reduction of the sex ratio could be partly explained by a clustered pregnancy loss of male zygotes in early pregnancy.

  1. Assigning sex and reproductive stage to adult Lake Sturgeon using ultrasonography and common morphological measurements

    USGS Publications Warehouse

    Chiotti, Justin A.; Boase, James C.; Hondorp, Darryl W.; Briggs, Andrew S.

    2016-01-01

    Sex determination of fish species is difficult to assess when sexual dimorphism and gametes are not apparent. For threatened and endangered fish species, noninvasive techniques are needed when determining sex to minimize stress and the potential for mortality. We evaluated the use of a portable ultrasound unit to determine sex of Lake Sturgeon Acipenser fulvescens in the field. Ultrasound images were collected from 9 yellow-egg (F2, F3), 32 black-egg (F4, F5), and 107 fully developed male (M2) Lake Sturgeon. Two readers accurately assigned sex to 88–96% of fish, but accuracy varied in relation to maturity stage. Black-egg females and fully developed males were correctly identified for 89–100% of the fish sampled, while these two readers identified yellow-egg females only 33% and 67% of the time. Time spent collecting images ranged between 2 and 3 min once the user was comfortable with operating procedures. Discriminant analysis revealed the total length : girth ratio was a strong predictor of sex and maturity, correctly classifying 81% of black-egg females and 97% of the fully developed males. However, yellow-egg females were incorrectly classified on all occasions. This study shows the utility of using ultrasonography and a total length : girth ratio for sex determination of Lake Sturgeon in later reproductive stages around the spawning season.

  2. Conflict between feminizing sex ratio distorters and an autosomal masculinizing gene in the terrestrial isopod Armadillidium vulgare Latr.

    PubMed

    Rigaud, T; Juchault, P

    1993-02-01

    Female sex determination in the pill bug Armadillidium vulgare is frequently under the control of feminizing parasitic sex factors (PSF). One of these PSF is an intracytoplasmic Wolbachia-like bacterium (F), while the other (f) is suspected of being an F-bacterial DNA sequence unstably integrated into the host genome. In most wild populations harboring PSF, all individuals are genetic males (ZZ), and female phenotypes occur only due to the presence of PSF which overrides the male determinant carried by the Z chromosome (females are thus ZZ +F or ZZ +f neo-females). Here we report the effects of the conflict between these PSF and a dominant autosomal masculinizing gene (M) on phenotypes. The M gene is able to override the feminizing effect of the f sex factor and, consequently, male sex may be restored. However, M is unable to restore male sex when competing with the F bacteria. It seems that the main effect of M is to delay the expression of F bacteria slightly, inducing intersex phenotypes. Most of these intersexes are functional females, able to transmit the masculinizing gene. The frequency of M and its effects on the sex ratio in wild populations are discussed. PMID:8436273

  3. Conflict between Feminizing Sex Ratio Distorters and an Autosomal Masculinizing Gene in the Terrestrial Isopod Armadillidium Vulgare Latr

    PubMed Central

    Rigaud, T.; Juchault, P.

    1993-01-01

    Female sex determination in the pill bug Armadillidium vulgare is frequently under the control of feminizing parasitic sex factors (PSF). One of these PSF is an intracytoplasmic Wolbachia-like bacterium (F), while the other (f) is suspected of being an F-bacterial DNA sequence unstably integrated into the host genome. In most wild populations harboring PSF, all individuals are genetic males (ZZ), and female phenotypes occur only due to the presence of PSF which overrides the male determinant carried by the Z chromosome (females are thus ZZ +F or ZZ +f neo-females). Here we report the effects of the conflict between these PSF and a dominant autosomal masculinizing gene (M) on phenotypes. The M gene is able to override the feminizing effect of the f sex factor and, consequently, male sex may be restored. However, M is unable to restore male sex when competing with the F bacteria. It seems that the main effect of M is to delay the expression of F bacteria slightly, inducing intersex phenotypes. Most of these intersexes are functional females, able to transmit the masculinizing gene. The frequency of M and its effects on the sex ratio in wild populations are discussed. PMID:8436273

  4. Sex ratio of congenital abnormalities in the function of maternal age: a population-based study.

    PubMed

    Csermely, Gyula; Urbán, Robert; Czeizel, Andrew E; Veszprémi, Béla

    2015-05-01

    Maternal age effect is well-known in the origin of numerical chromosomal aberrations and some isolated congenital abnormalities (CAs). The sex ratio (SR), i.e. number of males divided by the number of males and females together, of most CAs deviates from the SR of newborn population (0.51). The objective of this analysis was to evaluate the possible association of maternal age with the SR of isolated CAs in a population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. First, SR of 24 CA entities/groups was estimated in 21,494 patients with isolated CA. In the next step SR of different maternal age groups was compared to the mean SR of the given CA-groups. The SR of four CA-groups showed some deviation in certain maternal age groups. Cases with anencephaly had female excess in young mothers (<25 years). Cases with skull's CAs particularly craniosynostosis had a male excess in cases born to women over 30 years. Two other CA groups (cleft lip ± palate and valvar pulmonic stenosis within the group of right-sided obstructive defect of heart) had significant deviation in SR of certain maternal age groups from the mean SR, but these deviations were not harmonized with joining age groups and thus were considered as a chance effect due to multiple testing. In conclusion, our study did not suggest that in general SR of isolated CAs might be modified by certain maternal age groups with some exception such as anencephaly and craniosynostosis. PMID:25354028

  5. Operational sex ratio and density do not affect directional selection on male sexual ornaments and behavior.

    PubMed

    Head, Megan L; Lindholm, Anna K; Brooks, Robert

    2008-01-01

    Demographic parameters including operational sex ratio (OSR) and population density may influence the opportunity for, and strength of sexual selection. Traditionally, male-biased OSRs and high population densities have been thought to increase the opportunity for sexual selection on male sexual traits due to increased male competition for mates. Recent experimental evidence, however, suggests that male-biased OSRs might reduce the opportunity for sexual selection due to increased sexual coercion experienced by females. How OSR, density, and any resultant changes in the opportunity for sexual selection actually affect selection on male sexual traits is unclear. In this study, we independently manipulated OSR and density in the guppy (Poecilia reticulata) without altering the number of males present. We recorded male and female behavior and used DNA microsatellite data to assign paternity to offspring and estimate male reproductive success. We then used linear selection analyses to examine the effects of OSR and density on directional sexual selection on male behavioral and morphological traits. We found that females were pursued more by males in male-biased treatments, despite no change in individual male behavior. There were no differences in sexual behavior experienced by females or performed by males in relation to density. Neither OSR nor density significantly altered the opportunity for sexual selection. Also, Although there was significant multivariate linear selection operating on males, neither OSR nor density altered the pattern of sexual selection on male traits. Our results suggest that differences in either OSR or density (independent of the number of males present) are unlikely to alter directional evolutionary change in male sexual traits. PMID:18067568

  6. Superparasitism Drives Heritable Symbiont Epidemiology and Host Sex Ratio in a Wasp

    PubMed Central

    Parratt, Steven R.; Frost, Crystal L.; Schenkel, Martijn A.; Rice, Annabel

    2016-01-01

    Heritable microbial symbionts have profound impacts upon the biology of their arthropod hosts. Whilst our current understanding of the dynamics of these symbionts is typically cast within a framework of vertical transmission only, horizontal transmission has been observed in a number of cases. For instance, several symbionts can transmit horizontally when their parasitoid hosts share oviposition patches with uninfected conspecifics, a phenomenon called superparasitism. Despite this, horizontal transmission, and the host contact structures that facilitates it, have not been considered in heritable symbiont epidemiology. Here, we tested for the importance of host contact, and resulting horizontal transmission, for the epidemiology of a male-killing heritable symbiont (Arsenophonus nasoniae) in parasitoid wasp hosts. We observed that host contact through superparasitism is necessary for this symbiont’s spread in populations of its primary host Nasonia vitripennis, such that when superparasitism rates are high, A. nasoniae almost reaches fixation, causes highly female biased population sex ratios and consequently causes local host extinction. We further tested if natural interspecific variation in superparasitism behaviours predicted symbiont dynamics among parasitoid species. We found that A. nasoniae was maintained in laboratory populations of a closely related set of Nasonia species, but declined in other, more distantly related pteromalid hosts. The natural proclivity of a species to superparasitise was the primary factor determining symbiont persistence. Our results thus indicate that host contact behaviour is a key factor for heritable microbe dynamics when horizontal transmission is possible, and that ‘reproductive parasite’ phenotypes, such as male-killing, may be of secondary importance in the dynamics of such symbiont infections. PMID:27322651

  7. Effects of the Great East Japan Earthquake on Secondary Sex Ratio and Perinatal Outcomes

    PubMed Central

    Suzuki, Kohta; Yamagata, Zentaro; Kawado, Miyuki; Hashimoto, Shuji

    2016-01-01

    Background The effect of natural disasters on secondary sex ratio (SSR) and perinatal outcomes has been suggested. This study aimed to examine effects of the Great East Japan Earthquake on perinatal outcomes using vital statistics of Japan. Methods Birth registration data from vital statistics of Japan between March 2010 and March 2012 were used. Pregnant women who experienced the earthquake were categorized according to their gestational period as of March 11, 2011, as follows: gestational weeks 4–11, 12–19, 20–27, and 28–36 (2011 group). Similarly, pregnant women who did not experience the earthquake were categorized according to their gestational period as of March 11, 2010 and used as controls (2010 group). We also categorized prefectures as “extremely affected”, “moderately affected”, and “slightly or unaffected” regions. SSR, birth weight, and gestational period were compared between both groups. Results The number of singleton births was 688 479 in the 2010 group and 679 131 in the 2011 group. In the extremely affected region, the SSR among women at 4–11 weeks of gestation was significantly lower in the 2011 group compared with the 2010 group (49.8% vs 52.1%, P = 0.009). In the extremely affected region, children born to women who experienced the earthquake at 28–36 weeks of gestation had significantly lower birth weights. Conclusions The SSR declined among women who experienced the earthquake during early pregnancy, particularly in the extremely affected region. However, no apparent negative effect of the earthquake on perinatal outcomes was observed, although birth weight of infants who were born to women who experienced the earthquake at 28–36 weeks of gestation were lower. PMID:26639751

  8. Pornography consumption, cocaine use, and casual sex among U.S. adults.

    PubMed

    Wright, Paul J

    2012-08-01

    This study utilized nationally representative longitudinal survey data from the 2006-2008 General Social Survey (GSS) to explore the interplay between U.S. adults' self-reported past pornography consumption, past cocaine use, and recent participation in casual sex. Participants in the longitudinal component of the 2006-2008 GSS were 867 women and 669 men (N = 1,536) ranging in age from 18 to at least 89 years (M = 45.46; SD = 16.91). Hierarchical logistic regression analysis was employed to analyze the data. After controlling for past casual sex and demographic covariates, the interaction of past pornography consumption and past cocaine use on recent casual sex was significant. Past cocaine users were more likely than non-cocaine users to have had recent casual sex (OR = 4.56), but past pornography consumption was unrelated to recent casual sex for past cocaine users (OR= 0.20). Conversely, past pornography consumption was associated with an increase in the odds of recent casual sex for non-cocaine users (OR = 2.74). PMID:23045873

  9. Reactions to First Postpubertal Male Same-Sex Sexual Experience in the Kinsey Sample: A Comparison of Minors With Peers, Minors With Adults, and Adults With Adults.

    PubMed

    Rind, Bruce; Welter, Max

    2016-10-01

    Rind and Welter (2014) examined first postpubertal coitus using the Kinsey sample, finding that reactions were just as positive, and no more negative, among minors with adults compared to minors with peers and adults with adults. In the present study, we examined first postpubertal male same-sex sexual experiences in the Kinsey same-sex sample (i.e., participants mostly with extensive postpubertal same-sex behavior), comparing reactions across the same age categories. These data were collected between 1938 and 1961 (M year: 1946). Minors under age 18 years with adults (M ages: 14.0 and 30.5, respectively) reacted positively (i.e., enjoyed the experience "much") often (70 %) and emotionally negatively (e.g., fear, disgust, shame, regret) infrequently (16 %). These rates were the same as adults with adults (M ages: 21.2 and 25.9, respectively): 68 and 16 %, respectively. Minors with peers (M ages: 13.3 and 13.8, respectively) reacted positively significantly more often (82 %) and negatively nominally less often (9 %). Minors with adults reacted positively to intercourse (oral, anal) just as often (69 %) as to outercourse (body contact, masturbation, femoral) (72 %) and reacted emotionally negatively significantly less often (9 vs. 25 %, respectively). For younger minors (≤14) with adults aged 5-19 years older, reactions were just as positive (83 %) as for minors with peers within 1 year of age (84 %) and no more emotionally negative (11 vs. 7 %, respectively). Results are discussed in relation to findings regarding first coitus in the Kinsey sample and to the cultural context particular to Kinsey's time. PMID:27178172

  10. Sex ratio following preconception low-dose aspirin in women with prior pregnancy loss

    PubMed Central

    Radin, Rose G.; Mumford, Sunni L.; Silver, Robert M.; Lesher, Laurie L.; Galai, Noya; Faraggi, David; Wactawski-Wende, Jean; Townsend, Janet M.; Lynch, Anne M.; Simhan, Hyagriv N.; Sjaarda, Lindsey A.; Perkins, Neil J.; Zarek, Shvetha M.; Schliep, Karen C.; Schisterman, Enrique F.

    2015-01-01

    BACKGROUND. Several lines of evidence suggest that male embryos may have greater vulnerability than female embryos to disordered inflammation; therefore, antiinflammatory drugs, such as low-dose aspirin (LDA), may alter the sex ratio. Here, we assessed the effect of LDA on male live birth and male offspring, incorporating pregnancy losses (n = 56) via genetic assessment, as part of a parallel-design, block-randomized, placebo-controlled trial of preconception LDA. METHODS. Participants (615 treated with LDA, 613 treated with placebo) ranged in age from 18 to 40 years of age, with 1 to 2 prior pregnancy losses. We estimated the intention-to-treat (ITT) risk ratio (RR) and 95% CI and assessed interaction with baseline high-sensitivity C-reactive protein (hsCRP) serum concentration — a marker of systemic inflammation. RESULTS. Among the 1,078 women who completed follow-up (535 treated with LDA, 543 treated with placebo), the male live birth ITT RR equaled 1.31 (95% CI: 1.07–1.59). With increasing tertile of hsCRP, the proportion of males at birth decreased in the placebo group, and the effect of LDA on male live birth increased (first tertile: 48% male in LDA vs. 52% in placebo, ITT RR = 0.97, 95% CI: 0.70–1.35; second tertile: 57% male in LDA vs. 43% in placebo, ITT RR = 1.36, 95% CI: 0.98–1.90; third tertile: 53% male in LDA vs. 35% in placebo, ITT RR = 1.70, 95% CI: 1.13–2.57; P interaction = 0.03). Analysis of pregnancy with male offspring yielded similar results. CONCLUSION. Initiation of LDA prior to conception restored numbers of male live births and pregnancy with male offspring among women with 1 to 2 prior pregnancy losses. Moreover, our data suggest that LDA modulates inflammation that would otherwise reduce the conception or survival of male embryos. TRIAL REGISTRATION. ClinicalTrials.gov NCT00467363. FUNDING. Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of

  11. Maternal Lineage of Warmblood Mares Contributes to Variation of Gestation Length and Bias of Foal Sex Ratio

    PubMed Central

    Kuhl, J.; Stock, K. F.; Wulf, M.; Aurich, C.

    2015-01-01

    Maternal lineage influences performance traits in horses. This is probably caused by differences in mitochondrial DNA (mtDNA) transferred to the offspring via the oocyte. In the present study, we investigated if reproductive traits with high variability—gestation length and fetal sex ratio—are influenced by maternal lineage. Data from 142 Warmblood mares from the Brandenburg State Stud at Neustadt (Dosse), Germany, were available for the study. Mares were grouped according to their maternal lineage. Influences on the reproduction parameters gestation length and sex ratio of offspring were analyzed by simple and multiple analyses of variance. A total of 786 cases were included. From the 142 mares, 119 were assigned to six maternal lineages with n≥10 mares per lineage, and 23 mares belonged to smaller maternal lineages. The mean number of live foals produced per mare was 4.6±3.6 (±SD). Live foal rate was 83.5%. Mean gestation length was 338.5±8.9 days (±SD) with a range of 313 to 370 days. Gestation length was affected by maternal lineage (p<0.001). Gestation length was also significantly influenced by the individual mare, age of the mare, year of breeding, month of breeding and sex of the foal (p<0.05). Of the 640 foals born alive at term, 48% were male and 52% female. Mare age group and maternal lineage significantly influenced the sex ratio of the foals (p<0.05). It is concluded that maternal lineage influences reproductive parameters with high variation such as gestation length and foal sex ratio in horses. In young primiparous and aged mares, the percentage of female offspring is higher than the expected 1:1 ratio. PMID:26436555

  12. Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio)

    USGS Publications Warehouse

    Sharma, Prakash; Patino, Reynaldo

    2013-01-01

    We examined associations between thyroid condition, gonadal sex and pubertal development in zebrafish. Seventy-two-hour postfertilization larvae were reared in untreated medium or in the presence of goitrogens (sodium perchlorate, 0.82 mM; methimazole, 0.15 and 0.3 mM) or thyroxine (1 and 10 nM) for 30 days. Thyrocyte height, gonadal sex and gonadal development were histologically determined at 45 and 60 days postfertilization (dpf). Thyrocyte hypertrophy, an index of hypothyroidism, was observed at 45 and 60 dpf in perchlorate-treated but only at 45 dpf in methimazole-treated fish. Similarly, gonadal sex ratios were biased toward ovaries relative to control animals at 45 and 60 dpf in perchlorate-treated fish but only at 45 dpf in methimazole-treated fish. Gonadal sex ratios were biased toward testes at 45 and 60 dpf in thyroxine-treated fish. Spermatogenesis was delayed in testes from goitrogen-treated fish at 60 dpf relative to control values, but was unaffected in testes from thyroxine-treated individuals. Oogenesis seemed to be nonspecifically delayed in all treatments relative to control at 60 dpf. This study confirmed the previously reported association between hypothyroid condition and ovarian-skewed ratios, and hyperthyroid condition and testicular-skewed ratios, and also showed that male pubertal development is specifically delayed by experimental hypothyroidism. The simultaneous recovery from the hypothyroid and ovary-inducing effects of methimazole by 60 dpf (27 days post-treatment) suggests that the ovary-skewing effect of goitrogens is reversible when thyroid conditions return to basal levels before developmental commitment of gonadal sex. Conversely, the masculinizing effect of hyperthyroidism seems to be stable and perhaps permanent.

  13. The effect of childhood trauma on spatial cognition in adults: a possible role of sex.

    PubMed

    Syal, Supriya; Ipser, Jonathan; Phillips, Nicole; Thomas, Kevin G F; van der Honk, Jack; Stein, Dan J

    2014-06-01

    Although animal evidence indicates that early life trauma results in pervasive hippocampal deficits underlying spatial and cognitive impairment, visuo-spatial data from adult humans with early childhood adversity are lacking. We administered 4 tests of visuo-spatial ability from the Cambridge Neuorpsychological Test Automated Battery (CANTAB) to adults with a history of childhood trauma (measured by the Childhood Trauma Questionnaire) and a matched sample of healthy controls (trauma/control = 27/28). We observed a significant effect of trauma history on spatial/pattern learning. These effects could not be accounted for by adverse adult experiences, and were sex-specific, with prior adversity improving performance in men but worsening performance in women, relative to controls. Limitations include the small sample size and reliance of our study design on a retrospective, self report measure. Our results suggest that early adversity can lead to specific and pervasive deficits in adult cognitive function. PMID:24553877

  14. Sex differences in spatial navigation and perception in human adolescents and emerging adults

    PubMed Central

    Sneider, Jennifer Tropp; Hamilton, Derek A.; Cohen-Gilbert, Julia E.; Crowley, David J.; Rosso, Isabelle M.; Silveri, Marisa M.

    2014-01-01

    Males typically outperform females on spatial tasks, beginning early in life and continuing into adulthood. This study aimed to characterize age and sex differences in human spatial ability using a virtual Water Maze Task (vWMT), which is based on the classic Morris water maze spatial navigation task used in rodents. Performance on the vWMT and on a task assessing visuospatial perception, Mental Rotations Test (MRT), was examined in 33 adolescents and 39 emerging adults. For the vWMT, significant effects of age and sex were observed for path length in the target region (narrower spatial sampling), and heading error, with emerging adults performing better than adolescents, and an overall male advantage. For the MRT, males scored higher than females, but only in emerging adulthood. Overall, sex differences in visuospatial perception (MRT) emerge differently from those observed on a classic navigation task, with age and sex-specific superior vWMT performance likely related to the use of more efficient strategies. Importantly, these results extend the developmental timeline of spatial ability characterization to include adolescent males and females performing a virtual version of the classic vWMT. PMID:25464337

  15. Sex differences in spatial navigation and perception in human adolescents and emerging adults.

    PubMed

    Sneider, Jennifer T; Hamilton, Derek A; Cohen-Gilbert, Julia E; Crowley, David J; Rosso, Isabelle M; Silveri, Marisa M

    2015-02-01

    Males typically outperform females on spatial tasks, beginning early in life and continuing into adulthood. This study aimed to characterize age and sex differences in human spatial ability using a virtual Water Maze Task (vWMT), which is based on the classic Morris water maze spatial navigation task used in rodents. Performance on the vWMT and on a task assessing visuospatial perception, Mental Rotations Test (MRT), was examined in 33 adolescents and 39 emerging adults. For the vWMT, significant effects of age and sex were observed for path length in the target region (narrower spatial sampling), and heading error, with emerging adults performing better than adolescents, and an overall male advantage. For the MRT, males scored higher than females, but only in emerging adulthood. Overall, sex differences in visuospatial perception (MRT) emerge differently from those observed on a classic navigation task, with age and sex-specific superior vWMT performance likely related to the use of more efficient strategies. Importantly, these results extend the developmental timeline of spatial ability characterization to include adolescent males and females performing a virtual version of the classic vWMT. PMID:25464337

  16. Age- and sex-related changes in vibrotactile sensitivity of hand and face in neurotypical adults.

    PubMed

    Venkatesan, Lalit; Barlow, Steven M; Kieweg, Douglas

    2015-01-01

    Sensory perception decreases with age, and is altered as a function of sex. Very little is known about the age- and sex-related changes in vibrotactile detection thresholds (VDTs) of the face relative to the glabrous hand. This study utilized a single-interval up/down (SIUD) adaptive procedure to estimate the VDT for mechanical stimuli presented at 5, 10, 50, 150, 250, and 300 Hz at two sites on the face, including the right non-glabrous surface of the oral angle and the right lower lip vermilion; and on the hand on the glabrous surface of the distal phalanx of the right dominant index finger. Eighteen right-handed healthy younger adults and 18 right-handed healthy older adults participated in this study. VDTs were significantly different between the three stimulus sites (p < 0.0001), and dependent on stimulus frequency (p < 0.0001) and the sex of the participants (p < 0.005). VDTs were significantly higher for older adults when compared to younger adults for the finger stimulation condition (p < 0.05). There were significant differences (p < 0.05) in cheek and lower lip VDTs between male and female subjects. Difference in the VDTs between the three stimulation sites is presumed to reflect the unique typing and distribution of mechanoreceptors in the face and hand. Age-related differences in finger skin sensitivity are likely due to changes in the physical structure of skin, changes in the number and morphology of the mechanoreceptors, differences in the functional use of the hand, and its central representation. Sex-related differences in the VDTs may be due to the differences in tissue conformation and thickness, mechanoreceptor densities, skin hydration, or temperature characteristics. PMID:25248543

  17. The Effect of Sexual Experience on the Social Representation of Sex in Portuguese Young Adults

    PubMed Central

    Gomes, Alexandra; Nunes, Cristina

    2014-01-01

    This study aimed to observe the effect of sexual experience on the social representation of sex in Portuguese young adults. According to social representation theory, the central core of the social representation should be the same in all individuals that share a common social ground, however differences should be found in the peripheral system. It was used a free evocation task to assess the social representation of sex in Portuguese individuals aging between 18 and 25 years old. Nine hundred and sixty individuals were grouped by their sexual experience and condom use habits. A prototypical analysis was conducted to assess the structure of the social representation and statistical differences were analyzed using the qui-square independency test to search for an association between the structure and the group evoking it. The results supported the hypothesis of a common central core for all groups that shows a romanticized vision of sex. The differences found in the peripheral system suggest that sexual experience affects the representation of sex in a way that seems clearer to these individuals the necessity of protection when it comes to sex. PMID:26973936

  18. Clover root exudate produces male-biased sex ratios and accelerates male metamorphic timing in wood frogs

    PubMed Central

    Lambert, Max R.

    2015-01-01

    In amphibians, abnormal metamorph sex ratios and sexual development have almost exclusively been considered in response to synthetic compounds like pesticides or pharmaceuticals. However, endocrine-active plant chemicals (i.e. phytoestrogens) are commonly found in agricultural and urban waterways hosting frog populations with deviant sexual development. Yet the effects of these compounds on amphibian development remain predominantly unexplored. Legumes, like clover, are common in agricultural fields and urban yards and exude phytoestrogen mixtures from their roots. These root exudates serve important ecological functions and may also be a source of phytoestrogens in waterways. I show that clover root exudate produces male-biased sex ratios and accelerates male metamorphosis relative to females in low and intermediate doses of root exudate. My results indicate that root exudates are a potential source of contaminants impacting vertebrate development and that humans may be cultivating sexual abnormalities in wildlife by actively managing certain plant species. PMID:27019728

  19. Clover root exudate produces male-biased sex ratios and accelerates male metamorphic timing in wood frogs.

    PubMed

    Lambert, Max R

    2015-12-01

    In amphibians, abnormal metamorph sex ratios and sexual development have almost exclusively been considered in response to synthetic compounds like pesticides or pharmaceuticals. However, endocrine-active plant chemicals (i.e. phytoestrogens) are commonly found in agricultural and urban waterways hosting frog populations with deviant sexual development. Yet the effects of these compounds on amphibian development remain predominantly unexplored. Legumes, like clover, are common in agricultural fields and urban yards and exude phytoestrogen mixtures from their roots. These root exudates serve important ecological functions and may also be a source of phytoestrogens in waterways. I show that clover root exudate produces male-biased sex ratios and accelerates male metamorphosis relative to females in low and intermediate doses of root exudate. My results indicate that root exudates are a potential source of contaminants impacting vertebrate development and that humans may be cultivating sexual abnormalities in wildlife by actively managing certain plant species. PMID:27019728

  20. Germ-line origins of mutation in families with hemophilia B: The sex ratio varies with the type of mutation

    SciTech Connect

    Ketterling, R.P.; Vielhaber, E.; Bottema, C.D.K.; Schaid, D.J.; Sommer, S.S. ); Cohen, M.P. ); Sexauer, C.L. )

    1993-01-01

    Previous epidemiological and biochemical studies have generated conflicting estimates of the sex ratio of mutation. Direct genomic sequencing in combination with haplotype analysis extends previous analyses by allowing the precise mutation to be determined in a given family. From analysis of the factor IX gene of 260 consecutive families with hemophilia B, the authors report the germ-line origin of mutation in 25 families. When combined with 14 origins of mutation reported by others and with 4 origins previously reported by them, a total of 25 occur in the female germ line, and 18 occur in the male germ line. The excess of germ-line origins in females does not imply an overall excess mutation rate per base pair in the female germ line. Bayesian analysis of the data indicates that the sex ratio varies with the type of mutation. The aggregate of single-base substitutions shows a male predominance of germ-line mutations (P < .002). The maximum-likelihood estimate of the male predominance is 3.5-fold. Of the single-base substitutions, deletions display a sex ratio of unity. Analysis of the parental age at transmission of a new mutation suggests that germ-line mutations are associated with a small increase in parental age in females but little, if any, increase in males. Although direct genomic sequencing offers a general method for defining the origin of mutation in specific families, accurate estimates of the sex ratios of different mutational classes require large sample sizes and careful correction for multiple biases of ascertainment. The biases in the present data result in an underestimate of the enhancement of mutation in males. 62 refs., 1 fig., 5 tabs.

  1. Sex Differences in Performance over 7 Years on the Wechsler Intelligence Scale for Children Revised among Adults with Intellectual Disability

    ERIC Educational Resources Information Center

    Kittler, P.; Krinsky-McHale, S. J.; Devenny, D. A.

    2004-01-01

    The aim of this study was to explore changes related to sex differences on the Wechsler Intelligence Scale for Children Revised (WISC-R) subtest performance over a 7-year interval in middle-aged adults with intellectual disability (ID). Cognitive sex differences have been extensively studied in the general population, but there are few reports…

  2. Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio

    NASA Astrophysics Data System (ADS)

    Dama, Madhukar Shivajirao

    2013-06-01

    Human populations show remarkable variation in the sex ratio at birth which is believed to be related to the parental condition. In the present study, the global variation of sex ratio at birth (SRB, proportion of male offspring born) was analyzed with respect to indirect measure of condition, the intelligence quotient (IQ). IQ correlates strongly with lifespan across nations, which makes it a good indicator of health of the large populations. Relation between three standard measures of average national IQ and SRB was studied using multiple linear regression models. Average national IQ was positively correlated with SRB ( r = 0.54 to 0.57, p < 0.001). Further, IQ emerged as a powerful predictor of SRB after controlling for the effects of all the known covariates like fertility, maternal age, polygyny prevalence, wealth, son preference, latitude, low birth weight, and neonatal mortality in the regression models. These results suggest that the striking variation of offspring sex ratio across nations could be caused in part by the difference in general condition of populations.

  3. Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio.

    PubMed

    Dama, Madhukar Shivajirao

    2013-06-01

    Human populations show remarkable variation in the sex ratio at birth which is believed to be related to the parental condition. In the present study, the global variation of sex ratio at birth (SRB, proportion of male offspring born) was analyzed with respect to indirect measure of condition, the intelligence quotient (IQ). IQ correlates strongly with lifespan across nations, which makes it a good indicator of health of the large populations. Relation between three standard measures of average national IQ and SRB was studied using multiple linear regression models. Average national IQ was positively correlated with SRB (r = 0.54 to 0.57, p < 0.001). Further, IQ emerged as a powerful predictor of SRB after controlling for the effects of all the known covariates like fertility, maternal age, polygyny prevalence, wealth, son preference, latitude, low birth weight, and neonatal mortality in the regression models. These results suggest that the striking variation of offspring sex ratio across nations could be caused in part by the difference in general condition of populations. PMID:23657672

  4. Causes of Sex Ratio Bias May Account for Unisexual Sterility in Hybrids: A New Explanation of Haldane's Rule and Related Phenomena

    PubMed Central

    Hurst, L. D.; Pomiankowski, A.

    1991-01-01

    Unisexual hybrid disruption can be accounted for by interactions between sex ratio distorters which have diverged in the species of the hybrid cross. One class of unisexual hybrid disruption is described by Haldane's rule, namely that the sex which is absent, inviable or sterile is the heterogametic sex. This effect is mainly due to incompatibility between X and Y chromosomes. We propose that this incompatibility is due to a mutual imbalance between meiotic drive genes, which are more likely to evolve on sex chromosomes than autosomes. The incidences of taxa with sex chromosome drive closely matches those where Haldane's rule applies: Aves, Mammalia, Lepidoptera and Diptera. We predict that Haldane's rule is not universal but is correct for taxa with sex chromosome meiotic drive. A second class of hybrid disruption affects the male of the species regardless of which sex is heterogametic. Typically the genes responsible for this form of disruption are cytoplasmic. These instances are accounted for by the release from suppression of cytoplasmic sex ratio distorters when in a novel nuclear cytotype. Due to the exclusively maternal transmission of cytoplasm, cytoplasmic sex ratio distorters cause only female-biased sex ratios. This asymmetry explains why hybrid disruption is limited to the male. PMID:1916248

  5. Indirect effects of ploidy suggest X chromosome dose, not the X:A ratio, signals sex in Drosophila.

    PubMed

    Erickson, James W; Quintero, Jerome J

    2007-12-01

    In the textbook view, the ratio of X chromosomes to autosome sets, X:A, is the primary signal specifying sexual fate in Drosophila. An alternative idea is that X chromosome number signals sex through the direct actions of several X-encoded signal element (XSE) proteins. In this alternative, the influence of autosome dose on X chromosome counting is largely indirect. Haploids (1X;1A), which possess the male number of X chromosomes but the female X:A of 1.0, and triploid intersexes (XX;AAA), which possess a female dose of two X chromosomes and the ambiguous X:A ratio of 0.67, represent critical tests of these hypotheses. To directly address the effects of ploidy in primary sex determination, we compared the responses of the signal target, the female-specific SxlPe promoter of the switch gene Sex-lethal, in haploid, diploid, and triploid embryos. We found that haploids activate SxlPe because an extra precellular nuclear division elevates total X chromosome numbers and XSE levels beyond those in diploid males. Conversely, triploid embryos cellularize one cycle earlier than diploids, causing premature cessation of SxlPe expression. This prevents XX;AAA embryos from fully engaging the autoregulatory mechanism that maintains subsequent Sxl expression, causing them to develop as sexual mosaics. We conclude that the X:A ratio predicts sexual fate, but does not actively specify it. Instead, the instructive X chromosome signal is more appropriately seen as collective XSE dose in the early embryo. Our findings reiterate that correlations between X:A ratios and cell fates in other organisms need not implicate the value of the ratio as an active signal. PMID:18162044

  6. OXIDATIVE STRESS CONTRIBUTES TO SEX DIFFERENCES IN BLOOD PRESSURE IN ADULT GROWTH RESTRICTED OFFSPRING

    PubMed Central

    Ojeda, Norma B.; Hennington, Bettye Sue; Williamson, Danielle T.; Hill, Melanie L.; Betson, Nicole E.E.; Sartori-Valinotti, Julio C.; Reckelhoff, Jane F.; Royals, Thomas P.; Alexander, Barbara T.

    2013-01-01

    Numerous experimental studies suggest that oxidative stress contributes to the pathophysiology of hypertension and importantly, that oxidative stress plays a more definitive role in mediating hypertension in males than in females. Intrauterine growth-restriction induced by reduced uterine perfusion initiated at day 14 of gestation in the rat programs hypertension in adult male growth-restricted offspring; yet, female growth-restricted offspring are normotensive. The mechanisms mediating sex differences in blood pressure in adult growth-restricted offspring are not clear. Thus, this study tested the hypothesis that sex specific differences in renal oxidative stress contribute to the regulation of blood pressure in adult growth-restricted offspring. A significant increase in blood pressure measured by telemetry in male growth-restricted offspring (P<0.05) was associated with a marked increase in renal markers of oxidative stress (P<0.05). Chronic treatment with the antioxidant tempol had no effect on blood pressure in male control offspring, but it normalized blood pressure (P<0.05) and renal markers of oxidative stress (P<0.05) in male growth-restricted relative to male control. Renal markers of oxidative stress were not elevated in female growth-restricted offspring; however, renal activity of the antioxidant catalase was significantly elevated relative to female control (P<0.05). Chronic treatment with tempol did not significantly alter oxidative stress or blood pressure measured by telemetry in female offspring. Thus, these data suggest that sex differences in renal oxidative stress and antioxidant activity are present in adult growth-restricted offspring, and that oxidative stress may play a more important role in modulating blood pressure in male, but not female growth-restricted offspring. PMID:22585945

  7. Haldane’s Rule Is Linked to Extraordinary Sex Ratios and Sperm Length in Stalk-Eyed Flies

    PubMed Central

    Wilkinson, Gerald S.; Christianson, Sarah J.; Brand, Cara L.; Ru, George; Shell, Wyatt

    2014-01-01

    We use three allopatric populations of the stalk-eyed fly Teleopsis dalmanni from Southeast Asia to test two predictions made by the sex chromosome drive hypothesis for Haldane’s rule. The first is that modifiers that suppress or enhance drive should evolve rapidly and independently in isolated populations. The second is that drive loci or modifiers should also cause sterility in hybrid males. We tested these predictions by assaying the fertility of 2066 males derived from backcross experiments involving two pairs of populations and found that the proportion of mated males that fail to produce any offspring ranged from 38 to 60% among crosses with some males producing strongly female-biased or male-biased sex ratios. After genotyping each male at 25–28 genetic markers we found quantitative trait loci (QTL) that jointly influence male sterility, sperm length, and biased progeny sex ratios in each pair of populations, but almost no shared QTL between population crosses. We also discovered that the extant XSR chromosome has no effect on sex ratio or sterility in these backcross males. Whether shared QTL are caused by linkage or pleiotropy requires additional study. Nevertheless, these results indicate the presence of a “cryptic” drive system that is currently masked by suppressing elements that are associated with sterility and sperm length within but not between populations and, therefore, must have evolved since the populations became isolated, i.e., in <100,000 years. We discuss how genes that influence sperm length may contribute to hybrid sterility. PMID:25164880

  8. Sex and laterality differences in medial amygdala neurons and astrocytes of adult mice.

    PubMed

    Pfau, Daniel R; Hobbs, Nicholas J; Breedlove, S Marc; Jordan, Cynthia L

    2016-08-15

    The posterodorsal aspect of the medial amygdala (MePD) in rats is sexually dimorphic, being larger and containing more and larger neurons in males than in females. It is also highly lateralized, with the right MePD larger than the left in both sexes, but with the smaller left MePD actually containing more and larger neurons than the larger right. Astrocytes are also strikingly sexually differentiated, with male-biased numbers and lateralized favoring the right in the rat MePD. However, comparable information is scant for mice where genetic tools offer greater experimental power. Hence, we examined the MePD from adult male and female C57Bl/6(J) mice. We now report that the MePD is larger in males than in females, with the MePD in males containing more astrocytes and neurons than in females. However, we did not find sex differences in astrocyte complexity or overall glial number nor effects of laterality in either measure. While the mouse MePD is generally less lateralized than in rats, we did find that the sex difference in astrocyte number is only on the right because of a significant lateralization in females, with significantly fewer astrocytes on the right than the left but only in females. A sex difference in neuronal soma size favoring males was also evident, but only on the left. Sex differences in the number of neurons and astrocytes common to both rodent species may represent core morphological features that critically underlie the expression of sex-specific behaviors that depend on the MePD. J. Comp. Neurol. 524:2492-2502, 2016. © 2016 Wiley Periodicals, Inc. PMID:26780286

  9. Gene drive through a landscape: Reaction-diffusion models of population suppression and elimination by a sex ratio distorter.

    PubMed

    Beaghton, Andrea; Beaghton, Pantelis John; Burt, Austin

    2016-04-01

    Some genes or gene complexes are transmitted from parents to offspring at a greater-than-Mendelian rate, and can spread and persist in populations even if they cause some harm to the individuals carrying them. Such genes may be useful for controlling populations or species that are harmful. Driving-Y chromosomes may be particularly potent in this regard, as they produce a male-biased sex ratio that, if sufficiently extreme, can lead to population elimination. To better understand the potential of such genes to spread over a landscape, we have developed a series of reaction-diffusion models of a driving-Y chromosome in 1-D and radially-symmetric 2-D unbounded domains. The wild-type system at carrying capacity is found to be unstable to the introduction of driving-Y males for all models investigated. Numerical solutions exhibit travelling wave pulses and fronts, and analytical and semi-analytical solutions for the asymptotic wave speed under bounded initial conditions are derived. The driving-Y male invades the wild-type equilibrium state at the front of the wave and completely replaces the wild-type males, leaving behind, at the tail of the wave, a reduced- or zero-population state of females and driving-Y males only. In our simplest model of a population with one life stage and density-dependent mortality, wave speed depends on the strength of drive and the diffusion rate of Y-drive males, and is independent of the population dynamic consequences (suppression or elimination). Incorporating an immobile juvenile stage of fixed duration into the model reduces wave speed approximately in proportion to the relative time spent as a juvenile. If females mate just once in their life, storing sperm for subsequent reproduction, then wave speed depends on the movement of mated females as well as Y-drive males, and may be faster or slower than in the multiple-mating model, depending on the relative duration of juvenile and adult life stages. Numerical solutions are shown for

  10. Glomerular Filtration Rate and Urine Albumin to Creatinine Ratio Associated With Hearing Impairment Among Korean Adults With Diabetes

    PubMed Central

    Cho, Yunji; Kim, Do Hoon; Choi, June; Lee, Joo Kyung; Roh, Yong-Kyun; Nam, Hyo-Yun; Nam, Ga-Eun; Kim, Dong-Won; Lee, Seung-Hyun; Lee, Chung-Woo; Han, Kyungdo; Park, Yong-Gyu

    2016-01-01

    Abstract The objective of this study was to examine the association of estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (ACR) with hearing impairment among diabetic adults in Korea. The study was based on data from Korea National Health and Nutrition Examination Survey 2011 to 2012. Participants were 1206 diabetic adults, aged over 19 years, who completed audiometric testing supervised by nationally certified clinicians. Hearing impairment was defined in three grades: no hearing impairment (pure-tone average 0–25 dB), slight hearing impairment (26–40 dB), and disabling hearing impairment (>40 dB) in the better ear at frequencies 0.5, 1, 2, 3, 4 and 6 kHz. Using logistic regression, risk of hearing impairment was assessed after having controlled for confounding factors. Higher levels of ACR and lower levels of eGFR correlated with an increase in percentage of disabling hearing impairment both unilaterally and bilaterally (P < 0.001). Controlling for possible confounding covariates, odds ratios for hearing impairment showed tendency to increase in higher ACR groups (P for trend = 0.029). Similar pattern was examined between eGFR and hearing impairment (P for trend = 0.006). Odds ratios were 1.981 (1.146, 3.424) for ACR Q4 and 2.773 (1.286, 5.983) for eGFR < 60 mL/min. Fall in eGFR and rise in ACR correlated with severity of hearing impairment. The association existed independently of age, sex, body mass index (BMI), smoking, drinking, exercise, new onset of diabetes, education, income, mental stress, noise exposure, and metabolic syndrome. PMID:27124027

  11. Sex hormones affect neurotransmitters and shape the adult female brain during hormonal transition periods

    PubMed Central

    Barth, Claudia; Villringer, Arno; Sacher, Julia

    2015-01-01

    Sex hormones have been implicated in neurite outgrowth, synaptogenesis, dendritic branching, myelination and other important mechanisms of neural plasticity. Here we review the evidence from animal experiments and human studies reporting interactions between sex hormones and the dominant neurotransmitters, such as serotonin, dopamine, GABA and glutamate. We provide an overview of accumulating data during physiological and pathological conditions and discuss currently conceptualized theories on how sex hormones potentially trigger neuroplasticity changes through these four neurochemical systems. Many brain regions have been demonstrated to express high densities for estrogen- and progesterone receptors, such as the amygdala, the hypothalamus, and the hippocampus. As the hippocampus is of particular relevance in the context of mediating structural plasticity in the adult brain, we put particular emphasis on what evidence could be gathered thus far that links differences in behavior, neurochemical patterns and hippocampal structure to a changing hormonal environment. Finally, we discuss how physiologically occurring hormonal transition periods in humans can be used to model how changes in sex hormones influence functional connectivity, neurotransmission and brain structure in vivo. PMID:25750611

  12. Administration of estradiol benzoate before insemination could skew secondary sex ratio toward males in Holstein dairy cows.

    PubMed

    Emadi, S R; Rezaei, A; Bolourchi, M; Hovareshti, P; Akbarinejad, V

    2014-07-01

    The present study was conducted to investigate the effect of estradiol benzoate administration before insemination on secondary sex ratio (proportion of male calves at birth) in Holstein dairy cows. Cows (n = 1,647) were randomly assigned to 2 experimental groups by parity over a 1-yr period. Cows in the control group (n = 827; 232 primiparous and 595 multiparous cows) received 2 administrations of PGF2α (500 μg) 14 d apart, started at 30 to 35 d postpartum. Twelve d after the second PGF2α injection, cows received GnRH (100 μg), followed by administration of PGF2α 7 d later. Cows in the treatment group (n = 820; 238 primiparous and 582 multiparous cows) received the same hormonal administrations as the cows in the control group. Additionally, cows in the treatment group received estradiol benzoate (1 mg) 1 d after the third PGF2α injection. Estrus detection by visual observation was started 1 d after the third PGF2α injection and after estradiol administration in the control (for 6 d) and treatment (for 36 h) groups, respectively. Artificial insemination was carried out 12 h after observation of standing estrus. Exposure of cows to heat stress at conception was determined based on temperature-humidity index. Estrus detection rate was lower in primiparous than in multiparous cows (P < 0.05), but conception rate was higher in primiparous vs multiparous cows (P < 0.05). Estradiol administration improved estrus detection rate and fertility (P < 0.05); moreover, it increased secondary sex ratio (adjusted odds ratio: 1.645; P = 0.017). Exposure to heat stress diminished heat detection rate and fertility (P < 0.05), and altered secondary sex ratio toward males (adjusted odds ratio: 2.863; P = 0.012). In conclusion, the present study revealed that estradiol administration before insemination could improve fertility and increase the probability of calves being male in Holstein dairy cows. Moreover, the results showed that cows exposed to heat stress around

  13. Kinetics of fertilization and development, and sex ratio of bovine embryos produced using the semen of different bulls.

    PubMed

    Alomar, M; Tasiaux, H; Remacle, S; George, F; Paul, D; Donnay, I

    2008-08-01

    The between bulls variation in in vitro fertility and the shift of sex ratio towards male embryos are two problems affecting the in vitro production (IVP) of bovine embryos. Our objective was to evaluate the kinetics of fertilization, embryo development and the sex ratio of the resulting embryos using the frozen/thawed semen of four different bulls. In a first experiment, the kinetics of pronucleus (PN) formation was evaluated at 8, 12 and 18 h post-insemination (hpi). Based upon the pronuclei sizes and the distance between the two pronuclei, inseminated oocytes were classified in three PN stages. Differences between bulls were observed at each time point, but were more important at 12 hpi. At 8 and 12 hpi bull III showed a significantly faster PN evolution by comparison with the three other bulls (P<0.05), while at 18 hpi, the proportion of the three PN stages was similar to those of bulls I and IV, bull II being delayed. In a second experiment, the kinetics of in vitro embryo development was compared using time-lapse cinematography. The analysis of embryos reaching the blastocyst stage revealed significant differences in the mean time of first cleavage (range of 22.7-25.6h, P<0.05), while the lengths of the subsequent three cell cycles did not differ between bulls. The early mean time of first cleavage with bull III was associated with an early blastulation and a high blastocyst rate at Day 7, in opposition to what was observed with bull II showing a later timing of first cleavage (first cleavage 22.1 hpi versus 25.5 hpi; blastulation 140.4 hpi versus 152.5 hpi; D7 blastocyst rates: 31.3% versus 21.9%; P<0.05). In a third experiment, 65-76 Day 8 blastocysts per bull were sexed by PCR. Only blastocysts obtained with bull III showed a shift in sex ratio towards male embryos (76% male embryos; P<0.05). Such shift was already observed at the 2-cell and morula stages. In conclusion, the bull influences the kinetics of PN formation, of embryo development and the sex

  14. How Does Adult Attachment Affect Human Recognition of Love-related and Sex-related Stimuli: An ERP Study.

    PubMed

    Hou, Juan; Chen, Xin; Liu, Jinqun; Yao, Fangshu; Huang, Jiani; Ndasauka, Yamikani; Ma, Ru; Zhang, Yuting; Lan, Jing; Liu, Lu; Fang, Xiaoyi

    2016-01-01

    In the present study, we investigated the relationship among three emotion-motivation systems (adult attachment, romantic love, and sex). We recorded event-related potentials in 37 healthy volunteers who had experienced romantic love while they viewed SEX, LOVE, FRIEND, SPORT, and NEUTRAL images. We also measured adult attachment styles, level of passionate love and sexual attitudes. As expected, results showed that, firstly, response to love-related image-stimuli and sex-related image-stimuli on the electrophysiological data significantly different on N1, N2, and positive slow wave (PSW) components. Secondly, the different adult attachment styles affected individuals' recognition processing in response to love-related and sex-related images, especially, to sex-related images. Further analysis showed that voltages elicited by fearful attachment style individuals were significantly lower than voltages elicited by secure and dismissing attachment style individuals on sex-related images at frontal sites, on N1 and N2 components. Thirdly, from behavior data, we found that adult attachment styles were not significantly related to any dimension of sexual attitudes but were significantly related to passionate love scale (PLS) total points. Thus, the behavior results were not in line with the electrophysiological results. The present study proved that adult attachment styles might mediate individuals' lust and attraction systems. PMID:27199830

  15. How Does Adult Attachment Affect Human Recognition of Love-related and Sex-related Stimuli: An ERP Study

    PubMed Central

    Hou, Juan; Chen, Xin; Liu, Jinqun; Yao, Fangshu; Huang, Jiani; Ndasauka, Yamikani; Ma, Ru; Zhang, Yuting; Lan, Jing; Liu, Lu; Fang, Xiaoyi

    2016-01-01

    In the present study, we investigated the relationship among three emotion-motivation systems (adult attachment, romantic love, and sex). We recorded event-related potentials in 37 healthy volunteers who had experienced romantic love while they viewed SEX, LOVE, FRIEND, SPORT, and NEUTRAL images. We also measured adult attachment styles, level of passionate love and sexual attitudes. As expected, results showed that, firstly, response to love-related image-stimuli and sex-related image-stimuli on the electrophysiological data significantly different on N1, N2, and positive slow wave (PSW) components. Secondly, the different adult attachment styles affected individuals’ recognition processing in response to love-related and sex-related images, especially, to sex-related images. Further analysis showed that voltages elicited by fearful attachment style individuals were significantly lower than voltages elicited by secure and dismissing attachment style individuals on sex-related images at frontal sites, on N1 and N2 components. Thirdly, from behavior data, we found that adult attachment styles were not significantly related to any dimension of sexual attitudes but were significantly related to passionate love scale (PLS) total points. Thus, the behavior results were not in line with the electrophysiological results. The present study proved that adult attachment styles might mediate individuals’ lust and attraction systems. PMID:27199830

  16. Highly skewed sex ratios and biased fossil deposition of moa: ancient DNA provides new insight on New Zealand's extinct megafauna

    NASA Astrophysics Data System (ADS)

    Allentoft, Morten E.; Bunce, Michael; Scofield, R. Paul; Hale, Marie L.; Holdaway, Richard N.

    2010-03-01

    Ancient DNA was isolated from the bones of 267 individuals of the extinct New Zealand moa (Aves: Dinornithiformes) from two late Holocene deposits [Pyramid Valley (PV) and Bell Hill Vineyard (BHV)] located 5.7 km apart in North Canterbury, South Island. The two sites' combined fossil record cover the last 3000 years of pre-human New Zealand and mitochondrial DNA confirmed that four species ( Dinornis robustus, Euryapteryx curtus, Emeus crassus, and Pachyornis elephantopus) were sympatric in the region. However, the relative species compositions in the two deposits differed significantly with D. robustus and E. crassus being most abundant at PV while E. curtus outnumbered the other three moa taxa combined at BHV. A subsample of 227 individuals had sufficient nuclear DNA preservation to warrant the use of molecular sexing techniques, and the analyses uncovered a remarkable excess of females in both deposits with an overall male to female ratio of 1:5.1. Among juveniles of E. curtus, the only species which was represented by a substantial fraction of juveniles, the sex ratio was not skewed (10 ♂, 10 ♀), suggesting that the observed imbalance arose as a result of differential mortality during maturation. Surprisingly, sex ratios proved significantly different between sites with a 1:2.2 ratio at BHV ( n = 90) and 1:14.2 at PV ( n = 137). Given the mobility of large ratites, and the proximity of the two fossil assemblages in space and time, these differences in taxonomic and gender composition indicate that moa biology and the local environment have affected the fossil representation dramatically and several possible explanations are offered. Apart from adding to our understanding of moa biology, these discoveries reinforce the need for caution when basing interpretation of the fossil record on material from a single site.

  17. Sex Differences in the Use of Complementary and Alternative Medicine among Adults with Multiple Chronic Conditions

    PubMed Central

    Alwhaibi, Monira; Sambamoorthi, Usha

    2016-01-01

    Objective. To examine sex differences in complementary and alternative medicine (CAM) use among adults with multiple chronic conditions. Methods. This study used a cross-sectional design with data from the 2012 National Health Interview Survey. The participants were interviewed in 2012 and the reference period for the questions in the survey varied from 1 week to 12 months prior to the interview date. The study included adults (age > 21 years) with no missing data on CAM use variables and who had multiple chronic conditions. Multivariable regression analyses were used to examine the association between sex and CAM use. Results. A significantly higher percentage of women compared to men had ever used CAM (51.5% versus 44.3%); women were more likely to have ever used CAM (AOR = 1.49, 95% CI = 1.35–1.65). Among CAM users, a higher percentage of women compared to men used CAM in the past 12 months (53.5% vs. 42.7%); women were more likely to use CAM in the past 12 months (AOR = 1.71, 95% CI = 1.49–1.97). Factors associated with CAM use in the past 12 months were different for men and women; income and obesity were associated with CAM use in the past 12 months among women and not among men. Conclusion. Among adults with multiple chronic conditions, women were more likely to use CAM as compared to men. PMID:27239207

  18. Sex hormones establish a reserve pool of adult muscle stem cells.

    PubMed

    Kim, Ji-Hoon; Han, Gi-Chan; Seo, Ji-Yun; Park, Inkuk; Park, Wookjin; Jeong, Hyun-Woo; Lee, Su Hyeon; Bae, Sung-Hwan; Seong, Jinwoo; Yum, Min-Kyu; Hann, Sang-Hyeon; Kwon, Young-Guen; Seo, Daekwan; Choi, Man Ho; Kong, Young-Yun

    2016-09-01

    Quiescent satellite cells, known as adult muscle stem cells, possess a remarkable ability to regenerate skeletal muscle following injury throughout life. Although they mainly originate from multipotent stem/progenitor cells of the somite, the mechanism underlying the establishment of quiescent satellite cell populations is unknown. Here, we show that sex hormones induce Mind bomb 1 (Mib1) expression in myofibres at puberty, which activates Notch signalling in cycling juvenile satellite cells and causes them to be converted into adult quiescent satellite cells. Myofibres lacking Mib1 fail to send Notch signals to juvenile satellite cells, leading to impaired cell cycle exit and depletion. Our findings reveal that the hypothalamic-pituitary-gonadal axis drives Mib1 expression in the myofibre niche. Moreover, the same axis regulates the re-establishment of quiescent satellite cell populations following injury. Our data show that sex hormones establish adult quiescent satellite cell populations by regulating the myofibre niche at puberty and re-establish them during regeneration. PMID:27548913

  19. Sex Differences in the Use of Complementary and Alternative Medicine among Adults with Multiple Chronic Conditions.

    PubMed

    Alwhaibi, Monira; Sambamoorthi, Usha

    2016-01-01

    Objective. To examine sex differences in complementary and alternative medicine (CAM) use among adults with multiple chronic conditions. Methods. This study used a cross-sectional design with data from the 2012 National Health Interview Survey. The participants were interviewed in 2012 and the reference period for the questions in the survey varied from 1 week to 12 months prior to the interview date. The study included adults (age > 21 years) with no missing data on CAM use variables and who had multiple chronic conditions. Multivariable regression analyses were used to examine the association between sex and CAM use. Results. A significantly higher percentage of women compared to men had ever used CAM (51.5% versus 44.3%); women were more likely to have ever used CAM (AOR = 1.49, 95% CI = 1.35-1.65). Among CAM users, a higher percentage of women compared to men used CAM in the past 12 months (53.5% vs. 42.7%); women were more likely to use CAM in the past 12 months (AOR = 1.71, 95% CI = 1.49-1.97). Factors associated with CAM use in the past 12 months were different for men and women; income and obesity were associated with CAM use in the past 12 months among women and not among men. Conclusion. Among adults with multiple chronic conditions, women were more likely to use CAM as compared to men. PMID:27239207

  20. Body image and sexuality in Indonesian adults with a disorder of sex development (DSD).

    PubMed

    Ediati, Annastasia; Juniarto, Achmad Zulfa; Birnie, Erwin; Drop, Stenvert L S; Faradz, Sultana M H; Dessens, Arianne B

    2015-01-01

    In Indonesia, disorders of sex development (DSDs) are not well recognized and medical care for affected individuals is scarce. Consequently, many patients live with ambiguous genitalia and appearance. We compared reported outcomes on body image, sexual functioning, and sexual orientation of 39 adults with DSDs (aged 18 to 41) and 39 healthy controls matched for gender, age, and residential setting (urban, suburban, rural). Differences in gender and treatment status (treated or untreated) were also explored. On body image, adults with DSDs reported dissatisfaction with sex-related body parts. Compared to the matched controls, women with DSDs reported greater sexual distress, and men with DSDs reported lower erectile and ejaculation frequencies, and more dissatisfaction with sexual life but not with sexual desire and activities. Men with DSDs who had undergone genital surgery reported higher erectile and ejaculation frequencies than untreated men. More women than men in the DSDs group reported a nonexclusive heterosexual orientation. DSDs and infertility had a great impact on sexuality. Fear of ostracism complicated DSD acceptance. Findings were compared to those of Western studies. Based on these results, education about DSDs and their psychosexual consequences may help reduce the sexual distress and problems in adults with DSDs and improve quality of life. PMID:24144298

  1. Sex, but not Apolipoprotein E Polymorphism, Differences in Spatial Performance in Young Adults.

    PubMed

    Yasen, Alia L; Raber, Jacob; Miller, Jeremy K; Piper, Brian J

    2015-11-01

    The purpose of this study was to examine how sex and apolipoprotein E (APOE) genotype contribute to individual differences in spatial learning and memory. The associations of APOE genotype with neurocognitive function have been well studied among the elderly but less is known at earlier ages. Young adults (n = 169, 88 females) completed three neurocognitive tasks: mental rotation, spatial span, and Memory Island, a spatial navigation test. Males outperformed females on all three tasks: finding the hidden targets more quickly on Memory Island (Cohen's d = 0.62) and obtaining higher scores on mental rotation (d = 0.54) and spatial span (d = 0.37). In contrast, no significant effects of APOE were observed. The identified sex differences elaborate upon past literature documenting sexually dimorphic performance on specific neurobehavioral tasks. PMID:25750133

  2. Sex Differences in Adult Cognitive Deficits after Adolescent Nicotine Exposure in Rats

    PubMed Central

    Pickens, Laura R. G.; Rowan, James D.; Bevins, Rick A.; Fountain, Stephen B.

    2013-01-01

    This study was designed to determine whether deficits in adult serial pattern learning caused by adolescent nicotine exposure persist as impairments in asymptotic performance, whether adolescent nicotine exposure differentially retards learning about pattern elements that are inconsistent with “perfect” pattern structure, and whether there are sex differences in rats’ response to adolescent nicotine exposure as assessed by a serial multiple choice task. The current study replicated the results of our initial report (Fountain, Rowan, Kelley, Willey, & Nolley, 2008) using this task by showing that adolescent nicotine exposure (1.0 mg/kg/day nicotine for 35 days) produced a specific cognitive impairment in male rats that persisted into adulthood at least a month after adolescent nicotine exposure ended. In addition, sex differences were observed even in controls, with additional evidence that adolescent nicotine exposure significantly impaired learning relative to same-sex controls for chunk boundary elements in males and for violation elements in females. All nicotine-induced impairments were overcome by additional training so that groups did not differ at asymptote. An examination of the types of errors rats made indicated that adolescent nicotine exposure slowed learning without affecting rats’ cognitive strategy in the task. This data pattern suggests that exposure to nicotine in adolescence may have impaired different aspects of adult stimulus-response discrimination learning processes in males and females, but left abstract rule learning processes relatively spared in both sexes. These effects converge with other findings in the field and reinforce the concern that adolescent nicotine exposure poses an important threat to cognitive capacity in adulthood. PMID:23673345

  3. Endogenous brain erythropoietin is a potent sex-specific respiratory stimulant in adult and newborn mice.

    PubMed

    Ballot, Orlane; Joseph, Vincent; Soliz, Jorge

    2015-06-01

    We tested the hypothesis that endogenous brain Epo is a respiratory stimulant. Adult (3 mo) and newborn (10 days) male and female mice received an intracisternal (cisterna magna) injection of soluble Epo receptor (sEpoR; competes with EpoR to bind Epo; 50 μg/ml) or vehicle (0.1% BSA in PBS). Twenty-four hours after injection, we used whole body plethysmography to record minute ventilation (V̇e) tidal volume (VT), respiratory frequency (fR), O2 consumption (V̇o2), and CO2 production (V̇co2) under normoxia and progressive exposure to hypoxia (12-10-6% O2; 10 min each). In adult male and female mice sEpoR decreased normoxic V̇e (-25%), due to a decrease of VT in males and fR in females. Moreover, sEpoR injection decreased the ventilatory response to 12% O2, assessed as V̇e/V̇o2 or V̇e/V̇co2, in male but not in female mice. In newborn male and female mice sEpoR decreased V̇e (-37% in males, -59% in females) and VT (-38% in males, -47% in females) in normoxia and fR in females. During hypoxia, sEpoR decreased V̇e/V̇o2 and V̇e/V̇co2 in mice of both sexes. Upon extreme hypoxia (6% O2), the newborn mice treated with sEpoR showed respiratory depression, signs of asphyxia (gasping) and a high mortality rate in males and females. We concluded that endogenous brain Epo is a potent respiratory stimulant under normoxia and hypoxia in adult and newborn mice. Because sex-specific effects are different in newborn male and female, sex steroids secreted at different ages mice appear to modulate the effects of Epo on respiratory regulation in normoxia and in response to hypoxia. PMID:25792712

  4. Sex, drugs, and rock 'n' roll: caring for adolescents and young adults with cancer.

    PubMed

    Morgan, Sue; Davies, Simon; Palmer, Susan; Plaster, Meg

    2010-11-10

    Adolescents and young adults (AYAs) with cancer are a distinct group whose needs have been poorly addressed within health care systems. This imbalance is being addressed in some countries, and this growing specialty is now receiving the recognition it requires in order to develop further. This article discusses some of the psychosocial issues of AYAs and, with reference to the phrase of sex, drugs, and rock and roll, highlights the various rites of passage that young people experience. It also discusses how services and professionals can work alongside AYAs, enabling them to feel a part of the process by providing age-appropriate environment and expertise. PMID:20498401

  5. Sex- and Subtype-Related Differences in the Comorbidity of Adult ADHDs.

    PubMed

    Groß-Lesch, Silke; Dempfle, Astrid; Reichert, Susanne; Jans, Thomas; Geissler, Julia; Kittel-Schneider, Sarah; Nguyen, Thuy Trang; Reif, Andreas; Lesch, Klaus-Peter; Jacob, Christian Peter

    2013-11-01

    Objective: Comorbidity in adult ADHD (aADHD) has been investigated in a large number of studies using varying research approaches with divergent results. In contrast, there is limited information about sex- or subtype-related differences from studies with small sample size. Method: A large sample of 910 individuals (458 males, 452 females) affected with aADHD was recruited at a tertiary referral center. All probands underwent a four-step procedure for diagnosing aADHD, including the Structured Clinical Interview of Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) Axis I disorders to assess comorbidity. This study will provide additional information regarding the co-morbidity of Axis I disorders in the currently largest clinical referral sample. However, the main objective of this study is to gain information about sex- or subtype-related differences. Results: Affected females show higher rates of mood (61% vs. 49%), anxiety (32% vs. 22%), and eating disorders (16% vs. 1%) than affected males, while substance use disorders were more frequent in affected males (45% vs. 29%), which mirrors sex differences in prevalence in the general population. There were hardly any relevant differences in comorbidities between subtypes, with the exception of the inattentive subtype having an especially low prevalence of panic disorder. Comorbidity in general and substance use disorders in particular, but not sex or subtype, were highly predictive of lower psychosocial status. Conclusion: Sex-related differences in the comorbidity of aADHD are more pronounced than subtype-related differences. (J. of Att. Dis. XXXX; XX(X) XX-XX). PMID:24196345

  6. Sex disparity in childhood and young adult acute myeloid leukemia (AML) survival: Evidence from US population data.

    PubMed

    Hossain, Md Jobayer; Xie, Li

    2015-12-01

    Sex variation has been persistently investigated in studies concerning acute myeloid leukemia (AML) survival outcomes but has not been fully explored among pediatric and young adult AML patients. We detected sex difference in the survival of AML patients diagnosed at ages 0-24 years and explored distinct effects of sex across subgroups of age at diagnosis, race-ethnicity and AML subtypes utilizing the United States Surveillance Epidemiology and End Results (SEER) population based dataset of 4865 patients diagnosed with AML between 1973 and 2012. Kaplan-Meier survival function, propensity scores and stratified Cox proportional hazards regression were used for data analyses. After controlling for other prognostic factors, females showed a significant survival advantage over their male counterparts, adjusted hazard ratio (aHR, 95% confidence interval (CI): 1.09, 1.00-1.18). Compared to females, male patients had substantially increased risk of mortality in the following subgroups of: ages 20-24 years at diagnosis (aHR1.30), Caucasian (1.14), acute promyelocytic leukemia (APL) (1.35), acute erythroid leukemia (AEL) (1.39), AML with inv(16)(p13.1q22) (2.57), AML with minimum differentiation (1.47); and had substantially decreased aHR in AML t(9;11)(p22;q23) (0.57) and AML with maturation (0.82). Overall, females demonstrated increased survival over males and this disparity was considerably large in patients ages 20-24 years at diagnosis, Caucasians, and in AML subtypes of AML inv(16), APL and AEL. In contrast, males with AML t(9;11)(p22;q23), AML with maturation and age at diagnosis of 10-14 years showed survival benefit. Further investigations are needed to detect the biological processes influencing the mechanisms of these interactions. PMID:26520618

  7. Effects of a sex-ratio distorting endosymbiont on mtDNA variation in a global insect pest

    PubMed Central

    Delgado, Ana M; Cook, James M

    2009-01-01

    Background Patterns of mtDNA variation within a species reflect long-term population structure, but may also be influenced by maternally inherited endosymbionts, such as Wolbachia. These bacteria often alter host reproductive biology and can drive particular mtDNA haplotypes through populations. We investigated the impacts of Wolbachia infection and geography on mtDNA variation in the diamondback moth, a major global pest whose geographic distribution reflects both natural processes and transport via human agricultural activities. Results The mtDNA phylogeny of 95 individuals sampled from 10 countries on four continents revealed two major clades. One contained only Wolbachia-infected individuals from Malaysia and Kenya, while the other contained only uninfected individuals, from all countries including Malaysia and Kenya. Within the uninfected group was a further clade containing all individuals from Australasia and displaying very limited sequence variation. In contrast, a biparental nuclear gene phylogeny did not have infected and uninfected clades, supporting the notion that maternally-inherited Wolbachia are responsible for the mtDNA pattern. Only about 5% (15/306) of our global sample of individuals was infected with the plutWB1 isolate and even within infected local populations, many insects were uninfected. Comparisons of infected and uninfected isofemale lines revealed that plutWB1 is associated with sex ratio distortion. Uninfected lines have a 1:1 sex ratio, while infected ones show a 2:1 female bias. Conclusion The main correlate of mtDNA variation in P. xylostella is presence or absence of the plutWB1 infection. This is associated with substantial sex ratio distortion and the underlying mechanisms deserve further study. In contrast, geographic origin is a poor predictor of moth mtDNA sequences, reflecting human activity in moving the insects around the globe. The exception is a clade of Australasian individuals, which may reflect a bottleneck during

  8. An X-linked sex ratio distorter in Drosophila simulans that kills or incapacitates both noncarrier sperm and sons.

    PubMed

    Rice, William R

    2014-10-01

    Genomic conflict occurs when a genomic component gains a reproductive advantage at the expense of the organism as a whole. X-linked segregation distorters kill or incapacitate Y-bearing sperm, thereby gaining a transmission advantage but also reducing male fertility and generating a female-biased sex ratio. When some damaged, Y-bearing sperm survive and fertilize eggs, then the segregation distortion phenotype could be expanded by harming or killing sons in the next generation. X-linked son-killers are predicted by theory to be favored by natural selection and evolve when brothers and sisters compete for shared limiting resources and/or when brothers reduce the inclusive fitness of their sisters via sib-mating-a phenomenon called SA-zygotic drive. Here I develop and use a process-of-elimination screen to show that an unclassified X-linked sex ratio distorter (skew) in Drosophila simulans kills or incapacitates noncarrier sperm and also kills a substantial proportion of sons, i.e., it has both a segregation distortion and a SA-zygotic drive phenotype. There are three unique X-linked segregation distorters known to occur in D. simulans named Winters, Durham, and Paris. Autosomal-dominant suppressors of Winters (Nmy) and Durham (Tmy) failed to suppress skew. A Y-linked suppressor of Paris, however, did suppress skew, and a recombination test failed to detect recombinants between these two sex ratio distorters, indicating that they are tightly linked and plausibly identical or allelic. Son-killing may be an important yet unrecognized component of other X-linked segregation distorters. PMID:25081980

  9. An X-Linked Sex Ratio Distorter in Drosophila simulans That Kills or Incapacitates Both Noncarrier Sperm and Sons

    PubMed Central

    Rice, William R.

    2014-01-01

    Genomic conflict occurs when a genomic component gains a reproductive advantage at the expense of the organism as a whole. X-linked segregation distorters kill or incapacitate Y-bearing sperm, thereby gaining a transmission advantage but also reducing male fertility and generating a female-biased sex ratio. When some damaged, Y-bearing sperm survive and fertilize eggs, then the segregation distortion phenotype could be expanded by harming or killing sons in the next generation. X-linked son-killers are predicted by theory to be favored by natural selection and evolve when brothers and sisters compete for shared limiting resources and/or when brothers reduce the inclusive fitness of their sisters via sib-mating—a phenomenon called SA-zygotic drive. Here I develop and use a process-of-elimination screen to show that an unclassified X-linked sex ratio distorter (skew) in Drosophila simulans kills or incapacitates noncarrier sperm and also kills a substantial proportion of sons, i.e., it has both a segregation distortion and a SA-zygotic drive phenotype. There are three unique X-linked segregation distorters known to occur in D. simulans named Winters, Durham, and Paris. Autosomal-dominant suppressors of Winters (Nmy) and Durham (Tmy) failed to suppress skew. A Y-linked suppressor of Paris, however, did suppress skew, and a recombination test failed to detect recombinants between these two sex ratio distorters, indicating that they are tightly linked and plausibly identical or allelic. Son-killing may be an important yet unrecognized component of other X-linked segregation distorters. PMID:25081980

  10. Adult-child sex and the limits of liberal sexual morality.

    PubMed

    Malón, Agustin

    2015-05-01

    This article is a critical review of the most common arguments in the specialized literature about the moral status of sexual relationships between adults and prepubescent children. The intent is to reveal how the usual ethical analysis of these experiences, done from a general sexual morality, with a Kantian and utilitarian basis, very clearly shows us the limits and contradictions of contemporary liberal morality regarding sexual matters. It leaves open the possibility that, under certain circumstances, these relationships may be morally admissible. Some shortcomings and contradictions in these liberal arguments suggest that it would be of interest to refer to other authors and ideas to value adult-child sex, approaches that are based on a specific sexual morality concerning the issue of sexual virtues and a more complex conception of human sexual desire. Some of the scientific implications of these moral issues are also discussed. PMID:25677335

  11. Adolescent and young adult male sex offenders: understanding the role of recidivism.

    PubMed

    Riser, Diana K; Pegram, Sheri E; Farley, Julee P

    2013-01-01

    The current review explores the complex paths that can lead to adolescent and young adult males becoming sexually abusive. Because sexual abuse is an ongoing issue in our society that is often oversimplified, this article distinguishes between the various risk factors that predict sexually abusive behavior and types of sex offenders, particularly recidivistic offenders. It is imperative to focus on adolescents and young adults who sexually abuse because they represent a particularly important intervention point in preventing sexual abuse in comparison to older age groups and address the importance of differentiating among youths who sexually abuse, particularly between one-time offenders and recidivistic offenders. Implications for addressing these differences are discussed. PMID:23350537

  12. 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

  13. Anthropometric characteristics and body composition in Mexican older adults: age and sex differences.

    PubMed

    López-Ortega, Mariana; Arroyo, Pedro

    2016-02-14

    Anthropometric reference data for older adults, particularly for the oldest old, are still limited, especially in developing countries. The aim of the present study was to describe sex- and age-specific distributions of anthropometric measurements and body composition in Mexican older adults. The methods included in the present study were assessment of height, weight, BMI, calf circumference (CC), waist circumference (WC) and hip circumference (HC) as well as knee height in a sample of 8883 Mexican adults aged 60 years and above and the estimation of sex- and age-specific differences in these measures. Results of the study (n 7865, 54% women) showed that men are taller, have higher BMI, and larger WC than women, whereas women presented higher prevalence of obesity and adiposity. Overall prevalence of underweight was 2·3% in men and 4·0% in women, with increasing prevalence with advancing age. Significant differences were found by age group for weight, height, WC, HC, CC, BMI and knee height (P<0·001), but no significant differences in waist-hip circumference were observed. Significant differences between men and women were found in height, weight, circumferences, BMI and knee height (P<0·001). These results, which are consistent with studies of older adults in other countries, can be used for comparison with other Mexican samples including populations living in the USA and other countries with similar developmental and socio-economic conditions. This information can also be used as reference in clinical settings as a tool for detection of individuals at risk of either underweight or overweight and obesity. PMID:26597049

  14. First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA

    PubMed Central

    Allen, Camryn D.; Robbins, Michelle N.; Eguchi, Tomoharu; Owens, David W.; Meylan, Anne B.; Meylan, Peter A.; Kellar, Nicholas M.; Schwenter, Jeffrey A.; Nollens, Hendrik H.; LeRoux, Robin A.; Dutton, Peter H.; Seminoff, Jeffrey A.

    2015-01-01

    Determining sex ratios of endangered populations is important for wildlife management, particularly species subject to sex-specific threats or that exhibit temperature-dependent sex determination. Sea turtle sex is determined by incubation temperature and individuals lack external sex-based traits until sexual maturity. Previous research utilized serum/plasma testosterone radioimmunoassays (RIA) to determine sex in immature/juvenile sea turtles. However, there has been a growing application of enzyme-linked immunosorbent assay (ELISA) for wildlife endocrinology studies, but no study on sea turtles has compared the results of ELISA and RIA. This study provides the first sex ratio for a threatened East Pacific green sea turtle (Chelonia mydas) foraging aggregation, a critical step for future management of this species. Here, we validate a testosterone ELISA and compare results between RIA and ELISA of duplicate samples. The ELISA demonstrated excellent correspondence with the RIA for providing testosterone concentrations for sex determination. Neither assay proved reliable for predicting the sex of reproductively active females with increased testosterone production. We then applied ELISA to examine the sex ratio of 69 green turtles foraging in San Diego Bay, California. Of 45 immature turtles sampled, sex could not be determined for three turtles because testosterone concentrations fell between the ranges for either sex (females: 4.1–113.1 pg/mL, males: 198.4–2,613.0 pg/mL) and these turtles were not subsequently recaptured to enable sex determination; using a Bayesian model to predict probabilities of turtle sex we predicted all three ‘unknowns’ were female (> 0.86). Additionally, the model assigned all turtles with their correct sex (if determined at recapture) with 100% accuracy. Results indicated a female bias (2.83F:1M) among all turtles in the aggregation; when focusing only on putative immature turtles the sex ratio was 3.5F:1M. With appropriate

  15. First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA.

    PubMed

    Allen, Camryn D; Robbins, Michelle N; Eguchi, Tomoharu; Owens, David W; Meylan, Anne B; Meylan, Peter A; Kellar, Nicholas M; Schwenter, Jeffrey A; Nollens, Hendrik H; LeRoux, Robin A; Dutton, Peter H; Seminoff, Jeffrey A

    2015-01-01

    Determining sex ratios of endangered populations is important for wildlife management, particularly species subject to sex-specific threats or that exhibit temperature-dependent sex determination. Sea turtle sex is determined by incubation temperature and individuals lack external sex-based traits until sexual maturity. Previous research utilized serum/plasma testosterone radioimmunoassays (RIA) to determine sex in immature/juvenile sea turtles. However, there has been a growing application of enzyme-linked immunosorbent assay (ELISA) for wildlife endocrinology studies, but no study on sea turtles has compared the results of ELISA and RIA. This study provides the first sex ratio for a threatened East Pacific green sea turtle (Chelonia mydas) foraging aggregation, a critical step for future management of this species. Here, we validate a testosterone ELISA and compare results between RIA and ELISA of duplicate samples. The ELISA demonstrated excellent correspondence with the RIA for providing testosterone concentrations for sex determination. Neither assay proved reliable for predicting the sex of reproductively active females with increased testosterone production. We then applied ELISA to examine the sex ratio of 69 green turtles foraging in San Diego Bay, California. Of 45 immature turtles sampled, sex could not be determined for three turtles because testosterone concentrations fell between the ranges for either sex (females: 4.1-113.1 pg/mL, males: 198.4-2,613.0 pg/mL) and these turtles were not subsequently recaptured to enable sex determination; using a Bayesian model to predict probabilities of turtle sex we predicted all three 'unknowns' were female (> 0.86). Additionally, the model assigned all turtles with their correct sex (if determined at recapture) with 100% accuracy. Results indicated a female bias (2.83F:1M) among all turtles in the aggregation; when focusing only on putative immature turtles the sex ratio was 3.5F:1M. With appropriate validation

  16. Sex ratio and female sexual status of the coconut pest, Oryctes monoceros (Coleoptera: Dynastidae), differ in feeding galleries and pheromone-baited traps.

    PubMed

    Allou, K; Morin, J-P; Kouassi, P; Hala N'klo, F; Rochat, D

    2008-12-01

    Oryctes monoceros is a serious coconut pest, causing up to 40% damage in tropical Africa. Synthetic aggregation pheromone, ethyl 4-methyloctanoate, has been used to lure adults to traps. Traps with pheromone plus decaying palm material captured a high proportion of males. This raises the question whether individuals, which damage palms are receptive to the pheromone. We studied the sex ratio of the insects feeding on coconuts and those attracted to pheromone traps. Sixty two percent of adults from feeding galleries on living coconut palms were females. Pheromone with rotting palm material lured 43% females. To investigate the reasons for this difference, we compared the reproductive system of females lured to the odour traps or feeding in coconut galleries, or present in old rotting stems. Ninety six percent of the females trapped by pheromone had mated, and were sexually mature. In the galleries on living palms, 46% of females were immature, and 24% had not mated. In old rotting stems where eggs are laid and larvae develop, a mixture of 52% mated and 48% virgin females was found. Therefore, the pheromone together with the odour of rotting coconut stems signals a reproduction site to beetles, particularly mature females. In practice, the pheromone-baited traps will help in reducing the dissemination of gravid females, but will not affect directly the numbers of immature ones attacking palms. Our results show that when using pheromones for monitoring or controlling insects, the physiological status of the insects may have unexpected effects on the outcome. PMID:18662429

  17. Examining deterrence of adult sex crimes: A semi-parametric intervention time series approach

    PubMed Central

    Park, Jin-Hong; Bandyopadhyay, Dipankar; Letourneau, Elizabeth

    2013-01-01

    Motivated by recent developments on dimension reduction (DR) techniques for time series data, the association of a general deterrent effect towards South Carolina (SC)’s registration and notification (SORN) policy for preventing sex crimes was examined. Using adult sex crime arrestee data from 1990 to 2005, the the idea of Central Mean Subspace (CMS) is extended to intervention time series analysis (CMS-ITS) to model the sequential intervention effects of 1995 (the year SC’s SORN policy was initially implemented) and 1999 (the year the policy was revised to include online notification) on the time series spectrum. The CMS-ITS model estimation was achieved via kernel smoothing techniques, and compared to interrupted auto-regressive integrated time series (ARIMA) models. Simulation studies and application to the real data underscores our model’s ability towards achieving parsimony, and to detect intervention effects not earlier determined via traditional ARIMA models. From a public health perspective, findings from this study draw attention to the potential general deterrent effects of SC’s SORN policy. These findings are considered in light of the overall body of research on sex crime arrestee registration and notification policies, which remain controversial. PMID:24795489

  18. Sex differences in the composition of weight gain and loss in overweight and obese adults.

    PubMed

    Millward, D Joe; Truby, Helen; Fox, Kenneth R; Livingstone, M Barbara E; Macdonald, Ian A; Tothill, Peter

    2014-03-14

    Sex differences in the ratio of fat mass (FM):fat-free mass (FFM) during weight change should differentially affect the extent of weight change during energy imbalance in men and women. In the present study, we determined FM and FFM contents by dual-energy X-ray absorptiometry and calculated the P-ratios (protein energy/total energy) of excess weight and weight loss during a randomised controlled trial of four commercial weight loss regimens. Overweight and obese women (n 210) and men (n 77) were studied at baseline and at 2 and 6 months during weight loss on four dietary regimens: Dr Atkins' New Diet Revolution; The Slim-Fast Plan; Weight-Watchers programme; Rosemary Conley's Diet and Fitness Plan. At baseline, the percentage of FFM (%FFM) and P-ratios of excess weight were 40 % and 0·071 for men and 27 % and 0·039 for women. At 2 months, men had lost twice as much weight as women and three times more FFM than women, indicating higher FFM content and P-ratios of weight loss for men, 0·052, than for women, 0·029, with no dietary effects. Between 2 and 6 months, the rate at which weight was lost decreased and the %FFM of weight loss decreased to similar low levels in men (7 %) and women (5 %): i.e. P-ratios of 0·009 and 0·006, respectively, with no dietary effects. Thus, for men compared with women, there were greater FFM content and P-ratios of weight change, which could partly, but not completely, explain their greater weight loss at 2 months. However, protein-conserving adaptations occur with increasing weight loss and over time, more extensively in men, eventually eliminating any sex difference in the composition of weight loss. PMID:24103395

  19. Association of UV radiation with multiple sclerosis prevalence and sex ratio in France

    PubMed Central

    Orton, S.-M.; Wald, L.; Confavreux, C.; Vukusic, S.; Krohn, J.P.; Ramagopalan, S.V.; Herrera, B.M.; Sadovnick, A.D.

    2011-01-01

    Background: French farmers and their families constitute an informative population to study multiple sclerosis (MS) prevalence and related epidemiology. We carried out an ecological study to evaluate the association of MS prevalence and ultraviolet (UV) radiation, a candidate climatologic risk factor. Methods: Mean annual and winter (December–March) UVB irradiation values were systematically compared to MS prevalence rates in corresponding regions of France. UVB data were obtained from the solar radiation database (SoDa) service and prevalence rates from previously published data on 2,667 MS cases registered with the national farmer health insurance system, Mutualité Sociale Agricole (MSA). Pearson correlation was used to examine the relationship of annual and winter UVB values with MS prevalence. Male and female prevalence were also analyzed separately. Linear regression was used to test for interaction of annual and winter UVB with sex in predicting MS prevalence. Results: There was a strong association between MS prevalence and annual mean UVB irradiation (r = −0.80, p < 0.001) and average winter UVB (r = −0.87, p < 0.001). Both female (r = −0.76, p < 0.001) and male (r = −0.46, p = 0.032) prevalence rates were correlated with annual UVB. Regression modeling showed that the effect of UVB on prevalence rates differed by sex; the interaction effect was significant for both annual UVB (p = 0.003) and winter UVB (p = 0.002). Conclusions: The findings suggest that regional UVB radiation is predictive of corresponding MS prevalence rates and supports the hypothesis that sunlight exposure influences MS risk. The evidence also supports a potential role for gender-specific effects of UVB exposure. PMID:21282589

  20. Improvement of vitrification of in vitro produced buffalo embryos with special reference to sex ratio following vitrification.

    PubMed

    Mahmoud, K Gh M; Scholkamy, T H; Darwish, S F

    2015-01-01

    Cryopreservation and sexing of embryos are integrated into commercial embryo transfer technologies. To improve the effectiveness of vitrification of in vitro produced buffalo embryos, two experiments were conducted. The first evaluated the effect of exposure time (2 and 3 min) and developmental stage (morula and blastocysts) on the viability and development of vitrified buffalo embryos. Morphologically normal embryos and survival rates (re-expansion) significantly increased when vitrified morulae were exposed for 2 min compared to 3 min (P<0.001). On the other hand, morphologically normal and survival rates of blastocysts significantly increased when exposed for 3 min compared to 2 min (P<0.001). However, there were no significant differences between the two developmental stages (morulae and blastocystes) in the percentages of morphologically normal embryos and re-expansion rates after a 24 h culture. The second experiment aimed to evaluate the effect of viability on the sex ratio of buffalo embryos after vitrification and whether male and female embryos survived vitrification differently. A total number of 61 blastocysts were vitrified for 3 min with the same cryoprotectant as experiment 1. Higher percentages of males were recorded for live as compared to dead embryos; however, this difference was not significant. In conclusion, the post-thaw survival and development of in vitro produced morulae and blastocysts were found to be affected by exposure time rather than developmental stage. Survivability had no significant effect on the sex ratio of vitrified blastocysts; nevertheless, the number of surviving males was higher than dead male embryos. PMID:27175197

  1. Improvement of vitrification of in vitro produced buffalo embryos with special reference to sex ratio following vitrification

    PubMed Central

    Mahmoud, K. Gh. M; Scholkamy, T. H; Darwish, S. F

    2015-01-01

    Cryopreservation and sexing of embryos are integrated into commercial embryo transfer technologies. To improve the effectiveness of vitrification of in vitro produced buffalo embryos, two experiments were conducted. The first evaluated the effect of exposure time (2 and 3 min) and developmental stage (morula and blastocysts) on the viability and development of vitrified buffalo embryos. Morphologically normal embryos and survival rates (re-expansion) significantly increased when vitrified morulae were exposed for 2 min compared to 3 min (P<0.001). On the other hand, morphologically normal and survival rates of blastocysts significantly increased when exposed for 3 min compared to 2 min (P<0.001). However, there were no significant differences between the two developmental stages (morulae and blastocystes) in the percentages of morphologically normal embryos and re-expansion rates after a 24 h culture. The second experiment aimed to evaluate the effect of viability on the sex ratio of buffalo embryos after vitrification and whether male and female embryos survived vitrification differently. A total number of 61 blastocysts were vitrified for 3 min with the same cryoprotectant as experiment 1. Higher percentages of males were recorded for live as compared to dead embryos; however, this difference was not significant. In conclusion, the post-thaw survival and development of in vitro produced morulae and blastocysts were found to be affected by exposure time rather than developmental stage. Survivability had no significant effect on the sex ratio of vitrified blastocysts; nevertheless, the number of surviving males was higher than dead male embryos. PMID:27175197

  2. Hidden suppression of sex ratio distortion suggests Red queen dynamics between Wolbachia and its dwarf spider host.

    PubMed

    Vanthournout, B; Hendrickx, F

    2016-08-01

    Genetic conflict theory predicts strong selection for host nuclear factors suppressing endosymbiont effects on reproduction; however, evidence of these suppressors is currently scarce. This can either be caused by a low suppressor evolution rate, or if suppressors originate frequently, by rapid spread and concurrent masking of their activity by silencing the endosymbiont effect. To explore this, we use two populations of a dwarf spider with a similar female bias, caused by a Wolbachia infection. Using inter- and intrapopulation crosses, we determine that one of these populations demonstrates a higher suppressing capability towards Wolbachia despite having a similar population sex ratio. This suggests that spider and endosymbiont are locked in so-called red queen dynamics where, despite continuous coevolution, average fitness remains the same, hence hiding the presence of the suppressor. Finding different suppressor activity in populations that even lack phenotypic differentiation (i.e. similar sex ratio) further supports the hypothesis that suppressors originate often, but are often hidden by their own mode of action by countering endosymbiont effects. PMID:26995349

  3. Neuropsychological Sex Differences Associated with Age of Initiated Use Among Young Adult Cannabis Users

    PubMed Central

    Crane, Natania A.; Schuster, Randi Melissa; Mermelstein, Robin J.; Gonzalez, Raul

    2015-01-01

    Introduction Earlier initiation of cannabis use is associated with poorer neuropsychological functioning across several domains. Given well-documented sex differences in neuromaturation during adolescence, initiation of cannabis use during this time may affect neuropsychological functioning differently for males and females. Method In the current study, we examined sex differences in the relationship between age of initiated cannabis use and neuropsychological performance after controlling for amount of lifetime cannabis use in 44 male and 25 female young adult cannabis users. Results We found that an earlier age of initiated use was related to poorer episodic memory, especially immediate recall, in females, but not in males. On the other hand, we found that, surprisingly, an earlier age of initiated use was associated with better decision-making overall. However, exploratory analyses found sex-specific factors associated with decision-making and age of initiated use, specifically that ADHD symptoms in females may drive the relationship between an earlier age of initiated use and better decision-making. Further, an earlier age of initiated use was associated with less education, a lower IQ, and fewer years of mother’s education for females, but more lifetime cannabis use for males. Conclusions Taken together, our findings suggest there are sex-differences in the associations between age of initiated cannabis use and neuropsychological functioning. The current study provides preliminary evidence that males and females may have different neuropsychological vulnerabilities that place them at risk for initiating cannabis use and continued cannabis use, highlighting the importance of examining the impact of cannabis on neuropsychological functioning separately for males and females. PMID:25832823

  4. Evidence of female sex pheromones and characterization of the cuticular lipids of unfed, adult male versus female blacklegged ticks, Ixodes scapularis.

    PubMed

    Carr, Ann L; Sonenshine, Daniel E; Strider, John B; Roe, R Michael

    2016-04-01

    Copulation in Ixodes scapularis involves physical contact between the male and female (on or off the host), male mounting of the female, insertion/maintenance of the male chelicerae in the female genital pore (initiates spermatophore production), and the transfer of the spermatophore by the male into the female genital pore. Bioassays determined that male mounting behavior/chelicerae insertion required direct contact with the female likely requiring non-volatile chemical cues with no evidence of a female volatile sex pheromone to attract males. Unfed virgin adult females and replete mated adult females elicited the highest rates of male chelicerae insertion with part fed virgin adult females exhibiting a much lower response. Whole body surface hexane extracts of unfed virgin adult females and males, separately analyzed by GC-MS, identified a number of novel tick surface associated compounds: fatty alcohols (1-hexadecanol and 1-heptanol), a fatty amide (erucylamid), aromatic hydrocarbons, a short chain alkene (1-heptene), and a carboxylic acid ester (5β-androstane). These compounds are discussed in terms of their potential role in female-male communication. The two most abundant fatty acid esters found were butyl palmitate and butyl stearate present in ratios that were sex specific. Only 6 n-saturated hydrocarbons were identified in I. scapularis ranging from 10 to 18 carbons. PMID:26864785

  5. Morphology of the external genitalia of the adult male and female mice as an endpoint of sex differentiation

    PubMed Central

    Weiss, Dana A.; Rodriguez, Esequiel; Cunha, Tristan; Menshenina, Julia; Barcellos, Dale; Chan, Lok Yun; Risbridger, Gail; Baskin, Laurence; Cunha, Gerald

    2013-01-01

    Adult external genitalia (ExG) are the endpoints of normal sex differentiation. Detailed morphometric analysis and comparison of adult mouse ExG has revealed 10 homologous features distinguishing the penis and clitoris that define masculine vs. feminine sex differentiation. These features have enabled the construction of a simple metric to evaluate various intersex conditions in mutant or hormonally manipulated mice. This review focuses on the morphology of the adult mouse penis and clitoris through detailed analysis of histologic sections, scanning electron microscopy, and three-dimensional reconstruction. We also present previous results from evaluation of “non-traditional” mammals, such as the spotted hyena and wallaby to demonstrate the complex process of sex differentiation that involves not only androgen-dependent processes, but also estrogen-dependent and hormone-independent mechanisms. PMID:21893161

  6. Morphology of the external genitalia of the adult male and female mice as an endpoint of sex differentiation.

    PubMed

    Weiss, Dana A; Rodriguez, Esequiel; Cunha, Tristan; Menshenina, Julia; Barcellos, Dale; Chan, Lok Yun; Risbridger, Gail; Baskin, Laurence; Cunha, Gerald

    2012-05-01

    Adult external genitalia (ExG) are the endpoints of normal sex differentiation. Detailed morphometric analysis and comparison of adult mouse ExG has revealed 10 homologous features distinguishing the penis and clitoris that define masculine vs. feminine sex differentiation. These features have enabled the construction of a simple metric to evaluate various intersex conditions in mutant or hormonally manipulated mice. This review focuses on the morphology of the adult mouse penis and clitoris through detailed analysis of histologic sections, scanning electron microscopy, and three-dimensional reconstruction. We also present previous results from evaluation of "non-traditional" mammals, such as the spotted hyena and wallaby to demonstrate the complex process of sex differentiation that involves not only androgen-dependent processes, but also estrogen-dependent and hormone-independent mechanisms. PMID:21893161

  7. Sex-specific differences in risk factors for sarcopenia amongst community-dwelling older adults.

    PubMed

    Tay, L; Ding, Y Y; Leung, B P; Ismail, N H; Yeo, A; Yew, S; Tay, K S; Tan, C H; Chong, M S

    2015-12-01

    With considerable variation including potential sex-specific differential rate of skeletal muscle loss, identifying modifiable factors for sarcopenia will be pivotal to guide targeted interventions. This study seeks to identify clinical and biological correlates of sarcopenia in community-dwelling older adults, with emphasis on the role of anabolic and catabolic stimuli, and special reference to gender specificity. In this cross-sectional study involving 200 community-dwelling and functionally independent older adults aged ≥50 years, sarcopenia was defined using the Asian Working Group for Sarcopenia criteria. Comorbidities, cognitive and functional performance, physical activity and nutritional status were routinely assessed. Biochemical parameters included haematological indices, lipid panel, vitamin D level, anabolic hormones [insulin-like growth factor-1 (IGF-1), free testosterone (males only)] and catabolic markers [inflammatory markers (interleukin-6, C-reactive protein) and myostatin]. Multiple logistic regression was performed to identify independent predictors for sarcopenia. Age was associated with sarcopenia in both genders. Malnutrition conferred significantly higher odds for sarcopenia in women (OR = 5.71, 95% CI 1.13-28.84.44, p = 0.035) while higher but acceptable range serum triglyceride was protective in men (OR = 0.05, 95% CI 0.00-0.52, p = 0.012). Higher serum myostatin independently associated with higher odds for sarcopenia in men (OR = 1.11, 95% CI 1.00-1.24, p = 0.041). Serum IGF-1 was significantly lower amongst female sarcopenic subjects, with demonstrable trend for protective effect against sarcopenia in multiple regression models, such that each 1 ng/ml increase in IGF-1 was associated with 1% decline in odds of sarcopenia in women (p = 0.095). Our findings support differential pathophysiological mechanisms for sarcopenia that, if corroborated, may have clinical utility in guiding sex-specific targeted

  8. Does the maxillary anterior ratio in Korean adults follow the Golden Proportion?

    PubMed Central

    2016-01-01

    PURPOSE The purpose of this study was to determine the effect of changes in the horizontal plane angle on the mesiodistal width ratios of the maxillary anterior teeth during the acquisition of frontal view photographs, derive these ratios for Korean adults on the basis of the data obtained, and analyze them using the Golden Proportion as a reference. MATERIALS AND METHODS In experiment I, 30 plaster casts were mounted on an articulator and positioned on the angle-measuring device with a center setting of 0°. The device was rotated to 10° in 1° increments in a counterclockwise direction. At each angle, photographs were obtained and analyzed. Experiment II was based on 60 patients who visited the Department of Prosthodontics at Kyungpook National University Dental Hospital from February 2012 to February 2015. The patients were divided into three groups [Male (M), Female (F), Total (M + F)]. Frontal views were obtained for all groups and analyzed. RESULTS From 1° to 10°, the relative mesiodistal width ratios for the maxillary anterior teeth showed no significant differences from those at 0°. In all three groups, the relative width ratio of the maxillary central incisor was smaller than that specified in the Golden Proportion; the opposite was true for the canine. CONCLUSION Our results suggest that the mesiodistal width ratios of the maxillary anterior teeth do not follow the Golden Proportion in Korean adults, and that a change in the horizontal plane angle from 1° to 10° during frontal photography does not affect these ratios. PMID:27141256

  9. Immune function, sex ratios, and gonadal histopathology in double-crested cormorant chicks

    SciTech Connect

    Burull, E.J.; Goldberg, D.R.; Sileo, L.; Dale, T.; Allen, P.D.; Stromborg, K.L.; Larson, J.X.; Fry, D.M.

    1994-12-31

    There is evidence that environmental contaminants may be associated with endocrine and reproductive system abnormalities in colonial water birds. Little information is available on immune system response in chicks. Two double-crested cormorant (Phalocrocrozax auritus) colonies were monitored in 1993 for a comparative immune function study. Higher concentrations of organochlorines occurred in one colony. Parameters measured included: CBC, T and B-cell function, heterophil phagocytosis, lymphoid organ size and histopathology, and selected serum hormone analysis. Significant differences at the contaminated site included marked dysplasia and hypertrophy of thyroid gland, higher T3, lower cortisol, lower eosinophil counts, and increase phagocytosis at the contaminated site. Gonads of 101 deformed (cross-bill) chicks, siblings, and normal control chicks collected in 1992 and 1993 were examined microscopically because a sex-ration skewed towards females had been noted. Cross-billed chicks aged 12 to 15 days had disorganized or delayed follicular development which normalized by 20 days of age. Cross-billed or otherwise abnormal chicks aged 18 to 23 days had hypertrophic seminiferous tubules, a decreased interstitium, and decreased evidence of active Leydig cells.

  10. Finger length ratio (2D:4D) in adults with gender identity disorder.

    PubMed

    Kraemer, Bernd; Noll, Thomas; Delsignore, Aba; Milos, Gabriella; Schnyder, Ulrich; Hepp, Urs

    2009-06-01

    From early childhood, gender identity and the 2nd to 4th finger length ratio (2D:4D) are discriminative characteristics between sexes. Both the human brain and 2D:4D may be influenced by prenatal testosterone levels. This calls for an examination of 2D:4D in patients with gender identity disorder (GID) to study the possible influence of prenatal testosterone on gender identity. Until now, the only study carried out on this issue suggests lower prenatal testosterone levels in right-handed male-to-female GID patients (MtF). We compared 2D:4D of 56 GID patients (39 MtF; 17 female-to-male GID patients, FtM) with data from a control sample of 176 men and 190 women. Bivariate group comparisons showed that right hand 2D:4D in MtF was significantly higher (feminized) than in male controls, but similar to female controls. The comparison of 2D:4D ratios of biological women revealed significantly higher (feminized) values for right hands of right handed FtM. Analysis of variance confirmed significant effects for sex and for gender identity on 2D:4D ratios but not for sexual orientation or for the interaction among variables. Our results indirectly point to the possibility of a weak influence of reduced prenatal testosterone as an etiological factor in the multifactorially influenced development of MtF GID. The development of FtM GID seems even more unlikely to be notably influenced by prenatal testosterone. PMID:17906922

  11. Temporal variations of vegetative features, sex ratios and reproductive phenology in a Dictyota dichotoma (Dictyotales, Phaeophyceae) population of Argentina

    NASA Astrophysics Data System (ADS)

    Gauna, M. Cecilia; Cáceres, Eduardo J.; Parodi, Elisa R.

    2013-12-01

    This paper addresses the phenology of a Dictyota dichotoma population from the North Patagonian coasts of Argentina. The morphology of the individuals was characterized, and analyses of the temporal variations of vegetative features, diploid and haploid life cycle generations and sex ratios are provided. Individuals, represented by growing sporophytes and gametophytes, occurred simultaneously throughout the year. Morphological variables showed temporal variation, except the width and height of medullary cells, which did not vary between seasons. All vegetative variables were significantly correlated with daylength. Besides, frond length, frond dry mass and apical and basal branching angles were significantly correlated with seawater temperatures. Vegetative thalli were less abundant than haploid and diploid thalli. Sporophytes were less abundant than male and female gametophytes. Male gametophytes dominated in May, August, October and January, and female gametophytes were more abundant in September, November, December, February and March. The formation of female gametangia showed a significant correlation with daylength, and the highest number of gametangia was registered in spring. In general, the male/female sex ratio varied between 1:2 and 1:1. Apical regions were more fertile than basal regions. Our data about frequency in the formation of reproductive structures and male/female ratios are the first recorded in the Dictyota genus and thus could not be compared with populations from other regions of the world. Significant morphological variation was observed in thalli of both life cycle generations, regarding length and dry mass, number of primary branches and branching basal angle. In general, all variables analyzed varied seasonally except cortical cell width.

  12. Well-nourished women in a Solomon Islands society with a biased sex ratio.

    PubMed

    Furusawa, Takuro; Aswani, Shankar

    2011-03-01

    This study reports on the growth and nutritional status of females in Roviana (population 12 235), Solomon Islands, where there are fewer surviving females than males in all age groups (male/female = 1.10; Solomon Islands Government 2000). Anthropometric measurements were performed for 1243 voluntary participants from seven villages. The results showed that females were better nourished than males; weight-forage z-scores, for instance, were better for females than those for males throughout all age groups, with statistical significance in the following age groups: younger than 5 years, 10-14 years and 15-19 years. The same pattern was also observed for adults. Results suggest that gender inequality might not be caused by social discrimination. PMID:23008972

  13. Adult romantic relationships as contexts of human development: a multimethod comparison of same-sex couples with opposite-sex dating, engaged, and married dyads.

    PubMed

    Roisman, Glenn I; Clausell, Eric; Holland, Ashley; Fortuna, Keren; Elieff, Chryle

    2008-01-01

    This article presents a multimethod, multi-informant comparison of community samples of committed gay male (n=30) and lesbian (n=30) couples with both committed (n=50 young engaged and n=40 older married) and noncommitted (n=109 exclusively dating) heterosexual pairs. Specifically, in this study the quality of same- and opposite-sex relationships was examined at multiple levels of analysis via self-reports and partner reports, laboratory observations, and measures of physiological reactivity during dyadic interactions. Additionally, individuals in same-sex, engaged, and marital relationships were compared with one another on adult attachment security as assessed through the coherence of participants' narratives about their childhood experiences. Results indicated that individuals in committed same-sex relationships were generally not distinguishable from their committed heterosexual counterparts, with one exception--lesbians were especially effective at working together harmoniously in laboratory observations. PMID:18194008

  14. Sex-specific attentional deficits in adult vitamin D deficient BALB/c mice.

    PubMed

    Groves, Natalie J; Burne, Thomas H J

    2016-04-01

    Epidemiological studies have shown an association between vitamin D deficiency and cognitive impairment. However, there is a paucity of preclinical data showing that vitamin D deficiency is a causal factor for impaired cognitive processing. The aim of this study was to assess two cognitive tasks, the 5 choice-serial reaction task and the 5 choice-continuous performance task in adult vitamin D (AVD) deficient BALB/c mice. Ten-week old male and female BALB/c mice were fed a control or vitamin D deficient diet for 10 weeks prior to, and during behavioural testing. We found sex-dependent impairments in attentional processing and showed that male AVD-deficient mice were less accurate, took longer to respond when making a correct choice and were more likely to make an omission, without a change in the motivation to collect reward. By contrast, female AVD-deficient mice had a reduced latency to collect reward, but no changes on any other measures compared to controls. Therefore, we have shown that in otherwise healthy adult mice, vitamin D deficiency led to mild cognitive impairment in male but not female mice and therefore this model will be useful for future investigations into unravelling the mechanism by which vitamin D affects the adult brain and cognitive function. PMID:26836278

  15. Dietary and sex-specific factors regulate hypothalamic neurogenesis in young adult mice

    PubMed Central

    Lee, Daniel A.; Yoo, Sooyeon; Pak, Thomas; Salvatierra, Juan; Velarde, Esteban; Aja, Susan; Blackshaw, Seth

    2014-01-01

    The hypothalamus is the central regulator of a broad range of homeostatic and instinctive physiological processes, such as the sleep-wake cycle, food intake, and sexually dimorphic behaviors. These behaviors can be modified by various environmental and physiological cues, although the molecular and cellular mechanisms that mediate these effects remain poorly understood. Recently, it has become clear that both the juvenile and adult hypothalamus exhibit ongoing neurogenesis, which serve to modify homeostatic neural circuitry. In this report, we share new findings on the contributions of sex-specific and dietary factors to regulating neurogenesis in the hypothalamic mediobasal hypothalamus, a recently identified neurogenic niche. We report that high fat diet (HFD) selectively activates neurogenesis in the median eminence (ME) of young adult female but not male mice, and that focal irradiation of the ME in HFD-fed mice reduces weight gain in females but not males. These results suggest that some physiological effects of high fat diet are mediated by the stimulation of ME neurogenesis in a sexually dimorphic manner. We discuss these results in the context of recent advances in understanding the cellular and molecular mechanisms that regulate neurogenesis in postnatal and adult hypothalamus. PMID:24982613

  16. Ratio

    NASA Astrophysics Data System (ADS)

    Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

    2014-12-01

    Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

  17. The effects of gait time and trunk acceleration ratio during stair climbing in old-old adult females

    PubMed Central

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-01-01

    [Purpose] This study investigated the effects of gait time and trunk acceleration ratio in old-old adult females during stair climbing. [Subjects and Methods] Twenty-five older adult females who were able to walk independently volunteered for this study and were categorized into two age groups (older adults or old-old adults). Gait time and trunk acceleration ratio were measured using an accelerometer during stair climbing. [Results] Gait time and trunk acceleration ratio when climbing stairs were significantly higher in the old-old age group than in the older adults group. [Conclusions] These findings suggest that old-old females have decreased upper trunk control. In addition, gait time and the trunk acceleration ratio during stair climbing are useful clinical markers for predicting function and balance control ability in old-old elderly populations. PMID:27512256

  18. Live Birth Sex Ratio after In Vitro Fertilization and Embryo Transfer in China - An Analysis of 121,247 Babies from 18 Centers

    PubMed Central

    Bu, Zhiqin; Chen, Zi-Jiang; Huang, Guoning; Zhang, Hanwang; Sun, Haixiang; Sun, Yingpu

    2014-01-01

    In order to study the impact of procedures of IVF/ICSI technology on sex ratio in China, we conducted this multi-center retrospective study including 121,247 babies born to 93,895 women in China. There were 62,700 male babies and 58,477 female babies, making the sex ratio being 51.8% (Male: Female  = 107∶100). In univariate logistic regression analysis, sex ratio was imbalance toward females of 50.3% when ICSI was preformed compared to 47.7% when IVF was used (P<0.01). The sex ratio in IVF/ICSI babies was significantly higher toward males in transfers of blastocyst (54.9%) and thawed embryo (52.4%) when compared with transfers of cleavage stage embryo (51.4%) and fresh embryo (51.5%), respectively. Multiple delivery was not associated with sex ratio. However, in multivariable logistic regression analysis after controlling for related factors, only ICSI (adjusted OR = 0.90, 95%CI: 0.88–0.93; P<0.01) and blastocyst transfer (adjusted OR = 1.14, 95% CI: 1.09–1.20; P<0.01) were associated with sex ratio in IVF/ICSI babies. In conclusion, the live birth sex ratio in IVF/ICSI babies was influenced by the use of ICSI, which may decrease the percentage of male offspring, or the use of blastocyst transfer, which may increase the percentage of male offspring. PMID:25412419

  19. Perinatal Lead Exposure Alters Gut Microbiota Composition and Results in Sex-specific Bodyweight Increases in Adult Mice.

    PubMed

    Wu, Jianfeng; Wen, Xiaoquan William; Faulk, Christopher; Boehnke, Kevin; Zhang, Huapeng; Dolinoy, Dana C; Xi, Chuanwu

    2016-06-01

    Heavy metal pollution is a principle source of environmental contamination. Epidemiological and animal data suggest that early life lead (Pb) exposure results in critical effects on epigenetic gene regulation and child and adult weight trajectories. Using a mouse model of human-relevant exposure, we investigated the effects of perinatal Pb exposure on gut microbiota in adult mice, and the link between gut microbiota and bodyweight changes. Following Pb exposure during gestation and lactation via maternal drinking water, bodyweight in A(vy) strain wild-type non-agouti (a/a) offspring was tracked through adulthood. Gut microbiota of adult mice were characterized by deep DNA sequencing of bacterial 16S ribosomal RNA genes. Data analyses were stratified by sex and adjusted for litter effects. A Bayesian variable selection algorithm was used to analyze associations between bacterial operational taxonomic units and offspring adult bodyweight. Perinatal Pb exposure was associated with increased adult bodyweight in male (P < .05) but not in female offspring (P = .24). Cultivable aerobes decreased and anaerobes increased in Pb-exposed offspring (P < .005 and P < .05, respectively). Proportions of the 2 predominant phyla (Bacteroidetes and Firmicutes) shifted inversely with Pb exposure, and whole bacterial compositions were significantly different (analysis of molecular variance, P < .05) by Pb exposure without sex bias. In males, changes in gut microbiota were highly associated with adult bodyweight (P = .028; effect size = 2.59). Thus, perinatal Pb exposure results in altered adult gut microbiota regardless of sex, and these changes are highly correlated with increased bodyweight in males. Adult gut microbiota can be shaped by early exposures and may contribute to disease risks in a sex-specific manner. PMID:26962054

  20. The effects of sex, sexual orientation, and digit ratio (2D:4D) on mental rotation performance.

    PubMed

    Peters, Michael; Manning, John T; Reimers, Stian

    2007-04-01

    In spite of the reduced level of experimental control, this large scale study brought some clarity into the relation between mental rotation task (MRT) performance and a number of variables where contradictory associations had previously been reported in the literature. Clear sex differences in MRT were observed for a sample of 134,317 men and 120,783 women, with men outperforming women. There were also MRT differences as a function of sexual orientation: heterosexual men performed better than homosexual men and homosexual women performed better than heterosexual women. Although bisexual men performed better than homosexual men but less well than heterosexual men, no significant differences were observed between bisexual and homosexual women. MRT performance in both men and women peaked in the 20-30 year range, and declined significantly and markedly thereafter. Both men and women showed a significant negative correlation between left and right digit finger ratio and MRT scores, such that individuals with smaller digit ratios (relatively longer ring finger than index finger) performed better than individuals with larger digit ratios. PMID:17394056

  1. Latitudinal clines in bill length and sex ratio in a migratory shorebird: a case of resource partitioning?

    NASA Astrophysics Data System (ADS)

    Nebel, Silke

    2005-07-01

    Sexual segregation outside the mating season is common in vertebrates. This has been shown to arise through resource partitioning in a number of taxa, but never in avian migrants. Western sandpipers ( Calidris mauri) are migratory shorebirds that mainly breed in Alaska and overwinter along the coast in western and eastern North America down into South America. Females are slightly larger than males but have substantially longer bills. They migrate further south, resulting in a latitudinal bias in sex ratio. Resource partitioning could contribute to this pattern if (1) males and females forage on invertebrates buried at different sediment depths, and if (2) average prey burying depth changes with latitude. In accordance with the hypothesis, it was shown that female western sandpipers used a probing foraging mode more than males. Comparison of individuals overwintering in California, Mexico and Panama revealed that length of tarsus did not change among sites, while bill length increased in both males and females towards the south. Bill length residuals, corrected for length of tarsus, were also larger at a southern site. Between and within sexes, individuals with longer bills are thought to be favoured at southern latitudes because of a postulated general increase in invertebrate burying depth with higher ambient temperatures at lower latitudes. The implications of these findings for the evolution of sexual bill size dimorphism in shorebirds are discussed.

  2. Sex differences in the timing of identification among children and adults with autism spectrum disorders.

    PubMed

    Begeer, Sander; Mandell, David; Wijnker-Holmes, Bernadette; Venderbosch, Stance; Rem, Dorien; Stekelenburg, Fred; Koot, Hans M

    2013-05-01

    To examine differences by sex in the timing of identification of individuals with autism spectrum disorders (ASD), survey data were collected in the Netherlands from 2,275 males and females with autistic disorder, Asperger's syndrome and PDD-NOS. Among participants < 18 years of age, females with Asperger's syndrome were identified later than males. Among participants ≥ 18 years of age, females with autistic disorder were identified later than males. In more recent years, girls with Asperger's syndrome are diagnosed later than boys, confirming earlier findings. In adults, the delayed timing of diagnosis in females with autistic disorder may be related to changing practices in diagnosis over time. Strategies for changing clinician behaviour to improve recognition of ASD in females are needed. PMID:23001766

  3. Association between Homocysteine and Bone Mineral Density according to Age and Sex in Healthy Adults

    PubMed Central

    Kim, Joo Il; Moon, Ji Hyun; Chung, Hye Won; Kong, Mi Hee

    2016-01-01

    Background There are several studies about the relationship between serum homocysteine levels and bone mineral density (BMD), but the results are varied, and the studies are limited in Korea. In our study, the relationship between serum homocysteine levels and BMD by part according to age and sex is investigated. Methods From March 2012 to July 2015, the 3,337 healthy adults who took a medical examination were recruited. Subjects filled in the self-recording type questionnaire and physical examination, blood test, BMD of lumbar spine and femur were measured. After sorting by aging (≤49 year old, 50-59 year old, ≥60 year old) and sex, the results were adjusted with age and body mass index (BMI) and the relationship between serum homocysteine levels and BMD by lumbar spine and femur was analyzed by multiple regression analysis. Results As results of analysis, with the adjustment with age and BMI, all age groups of men had no significant relationship between log-converted serum homocysteine levels and BMD. In women aged under 50, there were significantly negative relationships at lumbar spine (β=-0.028, P=0.038), femur neck (β=-0.062, P=0.001), and total hip (β=-0.076, P<0.001), but there was no significant relationship in other age groups (50-59 year old and ≥60 year old). Conclusions As the serum homocysteine levels increased in women aged under 50, BMD of the lumbar spine and femur decreased, and correlations between homocysteine and BMD were different by sex and age. PMID:27622176

  4. Sex difference in substrate oxidation during low-intensity isometric exercise in young adults.

    PubMed

    Sarafian, Delphine; Schutz, Yves; Montani, Jean-Pierre; Dulloo, Abdul G; Miles-Chan, Jennifer L

    2016-09-01

    Low-intensity physical activity is increasingly promoted as an alternative to sedentary behavior. However, much research to date has focused on moderate- to vigorous-intensity physical activity, and in particular dynamic work, with the effect of low-intensity isometric exercise (<4 METs) on substrate utilization yet to be explored. Here we investigate the effects of such exercise on respiratory quotient (RQ) and determine the extent of intra- and inter-individual variability in response. Energy expenditure, RQ, and substrate oxidation were measured by ventilated-hood indirect calorimetry at rest and in response to standardized, intermittent, low-level isometric leg-press exercises at 5 loads (+5, +10, +15, +20, +25 kg) in 26 healthy, young adults. Nine participants repeated the experiment on 3 separate days to assess within-subject, between-day variability. There was no significant difference in energy cost and heart rate responses to low-intensity isometric exercise (<2 METs) between men and women. However, a sex difference was apparent in terms of substrate oxidation - with men increasing both fat and carbohydrate oxidation, and women only increasing fat oxidation while maintaining carbohydrate oxidation at baseline, resting levels. This sex difference was repeatable and persisted when substrate oxidation was adjusted for differences in body weight or body composition. Individual variability in RQ was relatively low, with both intra- and inter-individual coefficients of variation in the range of 3%-6% in both sexes. These results suggest that women preferentially increase fat oxidation during low-level isometric exercise. Whether such physical activity could be incorporated into treatment/prevention strategies aimed at optimizing fat oxidation in women warrants further investigation. PMID:27540628

  5. Sex differences in the intensity and qualitative dimensions of exertional dyspnea in physically active young adults.

    PubMed

    Cory, Julia M; Schaeffer, Michele R; Wilkie, Sabrina S; Ramsook, Andrew H; Puyat, Joseph H; Arbour, Brandon; Basran, Robbi; Lam, Michael; Les, Christian; MacDonald, Benjamin; Jensen, Dennis; Guenette, Jordan A

    2015-11-01

    Understanding sex differences in the qualitative dimensions of exertional dyspnea may provide insight into why women are more affected by this symptom than men. This study explored the evolution of the qualitative dimensions of dyspnea in 70 healthy, young, physically active adults (35 M and 35 F). Participants rated the intensity of their breathing discomfort (Borg 0-10 scale) and selected phrases that best described their breathing from a standardized list (work/effort, unsatisfied inspiration, and unsatisfied expiration) throughout each stage of a symptom-limited incremental-cycle exercise test. Following exercise, participants selected phrases that described their breathing at maximal exercise from a list of 15 standardized phrases. Intensity of breathing discomfort was significantly higher in women for a given ventilation, but differences disappeared when ventilation was expressed as a percentage of maximum voluntary ventilation. The dominant qualitative descriptor in both sexes throughout exercise was increased work/effort of breathing. At peak exercise, women were significantly more likely to select the following phrases: "my breathing feels shallow," "I cannot get enough air in," "I cannot take a deep breath in," and "my breath does not go in all the way." Women adopted a more rapid and shallow breathing pattern and had significantly higher end-inspiratory lung volumes relative to total lung capacity throughout exercise relative to men. These findings suggest that men and women do not differ in their perceived quality of dyspnea during submaximal exercise, but subjective differences appear at maximal exercise and may be related, at least in part, to underlying sex differences in breathing patterns and operating lung volumes during exercise. PMID:26338458

  6. Movie Ratings and the Content of Adult Videos: The Sex-Violence Ratio.

    ERIC Educational Resources Information Center

    Yang, Ni; Linz, Daniel

    1990-01-01

    Quantifies sexual, violent, sexually violent, and prosocial behaviors in a sample of R-rated and X-rated videocassettes. Finds the predominant behavior in both X- and XXX-rated videos is sexual. Finds the predominant behavior in R-rated videos was violence followed by prosocial behavior. (RS)

  7. BISPHENOL A EXPOSURE DURING EARLY DEVELOPMENT INDUCES SEX-SPECIFIC CHANGES IN ADULT ZEBRAFISH SOCIAL INTERACTIONS

    PubMed Central

    Weber, Daniel N.; Hoffmann, Raymond G.; Hoke, Elizabeth S.; Tanguay, Robert L.

    2014-01-01

    Developmental bisphenol A (BPA) exposure is associated with adverse behavioral effects, although underlying modes of action remain unclear. Because BPA is a suspected xenoestrogen, the objective was to identify sex-based changes in adult zebrafish social behavior developmentally exposed to BPA (0.0, 0.1 or 1 μM) or one of two control compounds (0.1μM 17β-estradiol [E2], and 0.1 μM GSK4716, a synthetic estrogen-related receptor γ ligand). A test chamber was divided lengthwise so each arena held one fish unable to detect the presence of the other fish. A mirror was inserted at one end of each arena; baseline activity levels were determined without mirror. Arenas were divided into 3, computer-generated zones to represent different distances from mirror image. Circadian rhythm patterns were evaluated at 1–3 (= AM) and 5–8 (= PM) hr postprandial. Adult zebrafish were placed into arenas and monitored by digital camera for 5 min. Total distance traveled, % time spent at mirror image, and number of attacks on mirror image were quantified. E2, GSK4716, and all BPA treatments dampened male activity and altered male circadian activity patterns; there was no marked effect on female activity. BPA induced non-monotonic effects (response curve changes direction within range of concentrations examined) on male % time at mirror only in AM. All treatments produced increased % time at the mirror during PM. Male attacks on the mirror were reduced by BPA exposure only during AM. There were sex-specific effects of developmental BPA on social interactions and time-of-day of observation affected results. PMID:25424546

  8. Differential Effects of Sex Pheromone Compounds on Adult Female Sea Lamprey (Petromyzon marinus) Locomotor Patterns.

    PubMed

    Walaszczyk, Erin J; Goheen, Benjamin B; Steibel, Juan Pedro; Li, Weiming

    2016-06-01

    Synchronization of male and female locomotor activity plays a critical role in ensuring reproductive success, especially in semelparous species. The goal of this study was to elucidate the effects of individual chemical signals, or pheromones, on the locomotor activity in the sea lamprey (Petromyzon marinus). In their native habitat, adult preovulated females (POF) and ovulated females (OF) are exposed to sex pheromone compounds that are released from spermiated males and attract females to nests during their migration and spawning periods. In this study, locomotor activity of individual POF and OF was measured hourly in controlled laboratory conditions using an automated video-tracking system. Differences in the activity between a baseline day (no treatment exposure) and a treatment day (sex pheromone compound or control exposure) were examined for daytime and nighttime periods. Results showed that different pheromone compound treatments affected both POF and OF sea lamprey (p < 0.05) but in different ways. Spermiated male washings (SMW) and one of its main components, 7α,12α,24-trihydroxy-5α-cholan-3-one 24 sulfate (3kPZS), decreased activity of POF during the nighttime. SMW also reduced activity in POF during the daytime. In contrast, SMW increased activity of OF during the daytime, and an additional compound found in SMW, petromyzonol sulfate (PZS), decreased the activity during the nighttime. In addition, we examined factors that allowed us to infer the overall locomotor patterns. SMW increased the maximum hourly activity during the daytime, decreased the maximum hourly activity during the nighttime, and reduced the percentage of nocturnal activity in OF. Our findings suggest that adult females have evolved to respond to different male compounds in regards to their locomotor activity before and after final maturation. This is a rare example of how species-wide chemosensory stimuli can affect not only the amounts of activity but also the overall locomotor

  9. Growth, age at metamorphosis, and sex ratio of northern brook lamprey in a tributary of southern Lake Superior

    USGS Publications Warehouse

    Purvis, Harold A.

    1970-01-01

    Growth was studied of five year classes of the northern brook lamprey, Ichthyomyzon fossor, collected from the Sturgeon River during intervals between treatment of the stream with a lampricide. Growth varied considerably among year classes. Larvae of the 1963 year class were slightly longer at age II and 30% longer at age III than the III-group larvae of the 1960 year class. About 6% of 558 III-group lampreys of the 1963 year class had metamorphosed by 17 August 1966. Although the sex ratio of larvae was about 1:1, 97% of the metamorphosed lampreys were males. The distribution of pigmentation on the caudal fin and upper lip in ammocoetes less than 40 mm long permitted accurate and rapid separation of northern brook lampreys from the sea lamprey, Petromyzon marinus.

  10. Neighbours' breeding success and the sex ratio of their offspring affect the mate preferences of female zebra finches.

    PubMed

    Drullion, Dominique; Dubois, Frédérique

    2011-01-01

    Several hypotheses on divorce predict that monogamous pairs should split up more frequently after a breeding failure. Yet, deviations from the expected pattern "success-stay, failure-leave" have been reported in several species. One possible explanation for these deviations would be that individuals do not use only their own breeding performance (i.e., private information) but also that of others (i.e., public information) to decide whether or not to divorce. To test this hypothesis, we investigated the relative importance of private and public information for mate choice decisions in female zebra finches (Taeniopygia guttata).We manipulated the reproductive performance of breeding pairs and measured females' preferences for their mate and the neighbouring male first following pair formation and then seven weeks later when all females had laid eggs and the young were independent. Although all females reduced their preference for their mate after a breeding failure, the decrease was significant only when the neighbouring pair had reproduced successfully. Furthermore, there was no evidence that females biased the sex ratio of their offspring according to their mate's attractiveness. On the other hand, after reproduction, both successful and unsuccessful females increased their preferences for males who had produced a larger proportion of sons. Despite the fact that other mechanisms may have also contributed to our findings, we suggest that females changed their mate preferences based on the proportion of sons produced by successful males, because offspring sex ratio reflects the male's testosterone level at the moment of fertilization and hence is an indicator of his immune condition. PMID:22216351

  11. Neighbours' Breeding Success and the Sex Ratio of Their Offspring Affect the Mate Preferences of Female Zebra Finches

    PubMed Central

    Drullion, Dominique; Dubois, Frédérique

    2011-01-01

    Several hypotheses on divorce predict that monogamous pairs should split up more frequently after a breeding failure. Yet, deviations from the expected pattern “success-stay, failure-leave” have been reported in several species. One possible explanation for these deviations would be that individuals do not use only their own breeding performance (i.e., private information) but also that of others (i.e., public information) to decide whether or not to divorce. To test this hypothesis, we investigated the relative importance of private and public information for mate choice decisions in female zebra finches (Taeniopygia guttata).We manipulated the reproductive performance of breeding pairs and measured females' preferences for their mate and the neighbouring male first following pair formation and then seven weeks later when all females had laid eggs and the young were independent. Although all females reduced their preference for their mate after a breeding failure, the decrease was significant only when the neighbouring pair had reproduced successfully. Furthermore, there was no evidence that females biased the sex ratio of their offspring according to their mate's attractiveness. On the other hand, after reproduction, both successful and unsuccessful females increased their preferences for males who had produced a larger proportion of sons. Despite the fact that other mechanisms may have also contributed to our findings, we suggest that females changed their mate preferences based on the proportion of sons produced by successful males, because offspring sex ratio reflects the male's testosterone level at the moment of fertilization and hence is an indicator of his immune condition. PMID:22216351

  12. Age at sexual maturity, sex ratio, fecundity, and longevity of isolated headwater populations of Westslope cutthroat trout

    USGS Publications Warehouse

    Downs, Christopher C.; White, R.G.; Shepard, B.B.

    1997-01-01

    We sampled 19 isolated headwater populations of westslope cutthroat trout Oncorhynchus clarki lewisi in Montana to provide estimates of fecundity, longevity, sex ratio, and age at sexual maturity. Fecundity was estimated for 31 fish collected from two streams in the upper Missouri River drainage. Females smaller than 149 mm fork length (FL) were generally immature and their fecundities could not be estimated. Mean fecundities (SD) were 227 eggs (41.1) for 150-174-mm fish, 346 eggs (85.6) for 175-199-mm fish, and 459 eggs (150.8) for 200-mm and larger fish. A linear regression model (two stream samples combined) to predict fecundity (E) from fork length was developed (E = -494.9 + 4.4.FL: r2 = 0.51, P < 0.001) for westslope cutthroat trout in the upper Missouri River drainage. Regression slopes of fecundity against fish length differed significantly (P < 0.01) between these and some of the previously studied populations. Steeper slopes were associated with lacustrine-adfluvial populations. The average sex ratio was 1.3 males per female across all sampled streams. Males began to mature sexually at age 2 and all were mature by age 4. Some females (27%) were sexually mature at age 3 and most of them (93%) were mature by age 5. Length was a better predictor of sexual maturity than age. Males matured at 110-160 mm and females at 150-180 mm FL. The maximum estimated age was 8 years based on otoliths from 475 fish collected from our 19 study streams and 14 additional streams.

  13. The relationship between paternal age, sex ratios, and aneuploidy frequencies in human sperm, as assessed by multicolor FISH

    SciTech Connect

    Martin, R.H.; Spriggs, E. |; Ko, E.

    1995-12-01

    We studied the frequencies of X- and Y-chromosome bearing sperm, diploidy and disomy for chromosomes 1, 12, X, and Y in sperm from 10 normal men aged 21 - 52 years, to determine whether there was any relationship between donor age and any of these variables. Multicolor FISH was used to control for lack of probe hybridization and to distinguish diploid sperm from disomic sperm. A minimum of 10,000 sperm per donor was evaluated for each chromosome, for a total of 225,846 sperm studied. Sperm were considered disomic if two fluorescent signals were separated by a minimal distance of one signal domain. The mean frequencies of X- and Y-bearing sperm were 50.1% and 49.0%, respectively; not significantly different from 50%. There was no correlation between paternal age and {open_quotes}sex ratio {close_quotes} in sperm. Similarly, there was no association between the frequency of diploid sperm (mean, .16%; range, .06%-.42%) and donor age. For disomy frequencies, there was no relationship between donor age and disomy 12 (mean, .16%; range, .10%-.25%), XX (mean, .07%; range, .03%-.17%), and XY sperm (mean, .16%; range, .08%-.24%). There was a significant increase in the frequency of YY sperm (P = .04; mean, .18%; range, .10%-.43%) and disomy 1 sperm (P = .01; mean, .11%; range, .05%-.18%) with donor age. In summary, our results do not support a correlation between paternal age and sex ratio or diploidy. A relationship between paternal age and disomy was observed for disomy 1 and YY sperm but not for disomy 12, XX or XY sperm. 37 refs., 3 tabs.

  14. Health consequences of same and opposite-sex unions: partnership, parenthood, and cardiovascular risk among young adults.

    PubMed

    Frech, Adrianne; Lynch, Jamie L; Barr, Peter

    2016-02-01

    We use the National Longitudinal Survey of Adolescent to Adult Health to examine union and parenthood differences across same and opposite-sex couples in systolic and diastolic blood pressure (SBP and DBP), C-reactive protein (CRP), and abdominal adiposity (waist circumference) among partnered (dating, cohabiting, married) young adults ages 25-33. Relative to women dating men, women cohabiting with women reported lower DBP and were less likely to have high CRP. Mothers reported lower SBP and DBP than non-mothers, but were more likely to have high waist circumference if they lived with a biological or step-child. Among men, nonresidential fathers reported higher DBP than nonfathers, and married men were more likely to have high waist circumference than men dating an opposite-sex partner. Same-sex cohabitation was neither a risk factor nor a health resource for men. Although the sample sizes for same-sex couples are quite small compared with those for opposite-sex couples, this study provides initial insight that occupying a sexual minority status while partnered is associated with some health benefits and few or no health risks relative to those who are dating an opposite sex partner. PMID:26323506

  15. Perceived Support from Adults, Interactions with Police, and Adolescents' Depressive Symptomology: An Examination of Sex, Race, and Social Class

    ERIC Educational Resources Information Center

    Tummala-Narra, Pratyusha; Sathasivam-Rueckert, Nina

    2013-01-01

    Several risk factors, including female sex, racial minority status, and family poverty, have been implicated in adolescents' depression. The present study focused on the role of one specific aspect of adolescents' ecological context, interactions with adults, in depressive symptomology. We examined the relationship between perceived support from…

  16. Mental Health Differences between Young Adults with and without Same-Sex Contact: A Simultaneous Examination of Underlying Mechanisms

    ERIC Educational Resources Information Center

    Ueno, Koji

    2010-01-01

    Previous research has documented that sexual minorities are more likely than heterosexual people to experience mental health problems, but little is known about how these disparities emerge. Analysis of data from Miami-Dade County, Florida, shows that young adults reporting same-sex contact have higher levels of depressive symptoms and drug use…

  17. Sex-specific effects of social networks on the prevalence, awareness, and control of hypertension among older Korean adults

    PubMed Central

    Baek, Jiwon; Hur, Nam Wook; Kim, Hyeon Chang; Youm, Yoosik

    2016-01-01

    Background Hypertension is a common chronic disease among older adults, and is associated with medical complications and mortality. This study aimed to examine the effects of social network characteristics on the prevalence, awareness, and control of hypertension among older adults. Methods The Korean Social Life, Health, and Aging Project (KSHAP) interviewed 814 ≥ 60-year-old residents and their spouses from a rural township between December 2011 and March 2012 (response rate: 95%). We evaluated the data from 595 participants. Multivariate logistic regression models were used to assess the effects of network characteristics on hypertension. Results We observed strong sex-specific network effects on the prevalence, awareness, and control of hypertension. Among older women, network density was associated with hypertension awareness [odds ratio (OR): 2.63, 95% confidence interval (CI): 1.03–5.37] and control (OR: 1.72; 95% CI: 0.94–3.13). Among older men, large networks were associated with a lower prevalence of hypertension (OR: 0.75; 95% CI: 0.58–0.96). Compared to older women, older men with coarse networks exhibited better hypertension awareness (OR: 0.37; 95% CI: 0.14–0.95) and control (OR: 0.42; 95% CI: 0.19–0.91). Network size interacted with density for hypertension control (P = 0.051), with controlled hypertension being associated with large and course networks. Conclusions A large network was associated with a lower risk for hypertension, and a coarse network was associated with hypertension awareness and control among older men. Older women with dense networks were most likely to exhibit hypertension awareness and control. PMID:27605938

  18. A preliminary study of sex differences in brain activation during a spatial navigation task in healthy adults.

    PubMed

    Sneider, Jennifer Tropp; Sava, Simona; Rogowska, Jadwiga; Yurgelun-Todd, Deborah A

    2011-10-01

    The hippocampus plays a significant role in spatial memory processing, with sex differences being prominent on various spatial tasks. This study examined sex differences in healthy adults, using functional magnetic resonance imaging (fMRI) in areas implicated in spatial processing during navigation of a virtual analogue of the Morris water-maze. There were three conditions: learning, hidden, and visible control. There were no significant differences in performance measures. However, sex differences were found in regional brain activation during learning in the right hippocampus, right parahippocampal gyrus, and the cingulate cortex. During the hidden condition, the hippocampus, parahippocampal gyrus, and cingulate cortex were activated in both men and women. Additional brain areas involved in spatial processing may be recruited in women when learning information about the environment, by utilizing external cues (landmarks) more than do men, contributing to the observed sex differences in brain activation. PMID:22185061

  19. The Jak-STAT target Chinmo prevents sex transformation of adult stem cells in the Drosophila testis niche

    PubMed Central

    Ma, Qing; Wawersik, Matthew; Matunis, Erika L.

    2014-01-01

    Local signals maintain adult stem cells in many tissues. Whether the sexual identity of adult stem cells must also be maintained was not known. In the adult Drosophila testis niche, local Jak-STAT signaling promotes somatic cyst stem cell (CySC) renewal through several effectors, including the putative transcription factor Chronologically inappropriate morphogenesis (Chinmo). Here, we find that Chinmo also prevents feminization of CySCs. Chinmo promotes expression of the canonical male sex determination factor DoublesexM (DsxM) within CySCs and their progeny, and ectopic expression of DsxM in the CySC lineage partially rescues the chinmo sex transformation phenotype, placing Chinmo upstream of DsxM. The Dsx homologue DMRT1 prevents the male-to female conversion of differentiated somatic cells in the adult mammalian testis, but its regulation is not well understood. Our work indicates that sex maintenance occurs in adult somatic stem cells, and that this highly conserved process is governed by effectors of niche signals. PMID:25453558

  20. Interpreting digit ratio (2D:4D)-behavior correlations: 2D:4D sex difference, stability, and behavioral correlates and their replicability in young children.

    PubMed

    Wong, Wang I; Hines, Melissa

    2016-02-01

    The popularity of using the ratio of the second to the fourth digit (2D:4D) to study influences of early androgen exposure on human behavior relies, in part, on a report that the ratio is sex-dimorphic and stable from age 2 years (Manning etal., 1998). However, subsequent research has rarely replicated this finding. Moreover, although 2D:4D has been correlated with many behaviors, these correlations are often inconsistent. Young children's 2D:4D-behavior correlations may be more consistent than those of older individuals, because young children have experienced fewer postnatal influences. To evaluate the usefulness of 2D:4D as a biomarker of prenatal androgen exposure in studies of 2D:4D-behavior correlations, we assessed its sex difference, temporal stability, and behavioral correlates over a 6- to 8-month period in 126, 2- to 3-year-old children, providing a rare same-sample replicability test. We found a moderate sex difference on both hands and high temporal stability. However, between-sex overlap and within-sex variability were also large. Only 3 of 24 correlations with sex-typed behaviors-scores on the Preschool Activities Inventory (PSAI), preference for a boy-typical toy, preference for a girl-typical toy, were significant and in the predicted direction, all of which involved the PSAI, partially confirming findings from another study. Correlation coefficients were larger for behaviors that showed larger sex differences. But, as in older samples, the overall pattern showed inconsistency across time, sex, and hand. Therefore, although sex-dimorphic and stable, 2D:4D-behavior correlations are no more consistent for young children than for older samples. Theoretical and methodological implications are discussed. PMID:26542674

  1. Chronic disuse and skeletal muscle structure in older adults: sex-specific differences and relationships to contractile function

    PubMed Central

    Callahan, Damien M.; Tourville, Timothy W.; Miller, Mark S.; Hackett, Sarah B.; Sharma, Himani; Cruickshank, Nicholas C.; Slauterbeck, James R.; Savage, Patrick D.; Ades, Philip A.; Maughan, David W.; Beynnon, Bruce D.

    2015-01-01

    In older adults, we examined the effect of chronic muscle disuse on skeletal muscle structure at the tissue, cellular, organellar, and molecular levels and its relationship to muscle function. Volunteers with advanced-stage knee osteoarthritis (OA, n = 16) were recruited to reflect the effects of chronic lower extremity muscle disuse and compared with recreationally active controls (n = 15) without knee OA but similar in age, sex, and health status. In the OA group, quadriceps muscle and single-fiber cross-sectional area were reduced, with the largest reduction in myosin heavy chain IIA fibers. Myosin heavy chain IIAX fibers were more prevalent in the OA group, and their atrophy was sex-specific: men showed a reduction in cross-sectional area, and women showed no differences. Myofibrillar ultrastructure, myonuclear content, and mitochondrial content and morphology generally did not differ between groups, with the exception of sex-specific adaptations in subsarcolemmal (SS) mitochondria, which were driven by lower values in OA women. SS mitochondrial content was also differently related to cellular and molecular functional parameters by sex: greater SS mitochondrial content was associated with improved contractility in women but reduced function in men. Collectively, these results demonstrate sex-specific structural phenotypes at the cellular and organellar levels with chronic disuse in older adults, with novel associations between energetic and contractile systems. PMID:25810256

  2. Race and Sex Differences in Small-Molecule Metabolites and Metabolic Hormones in Overweight and Obese Adults

    PubMed Central

    Patel, Mahesh J.; Batch, Bryan C.; Svetkey, Laura P.; Bain, James R.; Turer, Christy Boling; Haynes, Carol; Muehlbauer, Michael J.; Stevens, Robert D.; Newgard, Christopher B.

    2013-01-01

    Abstract In overweight/obese individuals, cardiometabolic risk factors differ by race and sex categories. Small-molecule metabolites and metabolic hormone levels might also differ across these categories and contribute to risk factor heterogeneity. To explore this possibility, we performed a cross-sectional analysis of fasting plasma levels of 69 small-molecule metabolites and 13 metabolic hormones in 500 overweight/obese adults who participated in the Weight Loss Maintenance trial. Principal-components analysis (PCA) was used for reduction of metabolite data. Race and sex-stratified comparisons of metabolite factors and metabolic hormones were performed. African Americans represented 37.4% of the study participants, and females 63.0%. Of thirteen metabolite factors identified, three differed by race and sex: levels of factor 3 (branched-chain amino acids and related metabolites, p<0.0001), factor 6 (long-chain acylcarnitines, p<0.01), and factor 2 (medium-chain dicarboxylated acylcarnitines, p<0.0001) were higher in males vs. females; factor 6 levels were higher in Caucasians vs. African Americans (p<0.0001). Significant differences were also observed in hormones regulating body weight homeostasis. Among overweight/obese adults, there are significant race and sex differences in small-molecule metabolites and metabolic hormones; these differences may contribute to risk factor heterogeneity across race and sex subgroups and should be considered in future investigations with circulating metabolites and metabolic hormones. PMID:24117402

  3. The Influence of Age and Sex on Genetic Associations with Adult Body Size and Shape: A Large-Scale Genome-Wide Interaction Study.

    PubMed

    Winkler, Thomas W; Justice, Anne E; Graff, Mariaelisa; Barata, Llilda; Feitosa, Mary F; Chu, Su; Czajkowski, Jacek; Esko, Tõnu; Fall, Tove; Kilpeläinen, Tuomas O; Lu, Yingchang; Mägi, Reedik; Mihailov, Evelin; Pers, Tune H; Rüeger, Sina; Teumer, Alexander; Ehret, Georg B; Ferreira, Teresa; Heard-Costa, Nancy L; Karjalainen, Juha; Lagou, Vasiliki; Mahajan, Anubha; Neinast, Michael D; Prokopenko, Inga; Simino, Jeannette; Teslovich, Tanya M; Jansen, Rick; Westra, Harm-Jan; White, Charles C; Absher, Devin; Ahluwalia, Tarunveer S; Ahmad, Shafqat; Albrecht, Eva; Alves, Alexessander Couto; Bragg-Gresham, Jennifer L; de Craen, Anton J M; Bis, Joshua C; Bonnefond, Amélie; Boucher, Gabrielle; Cadby, Gemma; Cheng, Yu-Ching; Chiang, Charleston W K; Delgado, Graciela; Demirkan, Ayse; Dueker, Nicole; Eklund, Niina; Eiriksdottir, Gudny; Eriksson, Joel; Feenstra, Bjarke; Fischer, Krista; Frau, Francesca; Galesloot, Tessel E; Geller, Frank; Goel, Anuj; Gorski, Mathias; Grammer, Tanja B; Gustafsson, Stefan; Haitjema, Saskia; Hottenga, Jouke-Jan; Huffman, Jennifer E; Jackson, Anne U; Jacobs, Kevin B; Johansson, Åsa; Kaakinen, Marika; Kleber, Marcus E; Lahti, Jari; Mateo Leach, Irene; Lehne, Benjamin; Liu, Youfang; Lo, Ken Sin; Lorentzon, Mattias; Luan, Jian'an; Madden, Pamela A F; Mangino, Massimo; McKnight, Barbara; Medina-Gomez, Carolina; Monda, Keri L; Montasser, May E; Müller, Gabriele; Müller-Nurasyid, Martina; Nolte, Ilja M; Panoutsopoulou, Kalliope; Pascoe, Laura; Paternoster, Lavinia; Rayner, Nigel W; Renström, Frida; Rizzi, Federica; Rose, Lynda M; Ryan, Kathy A; Salo, Perttu; Sanna, Serena; Scharnagl, Hubert; Shi, Jianxin; Smith, Albert Vernon; Southam, Lorraine; Stančáková, Alena; Steinthorsdottir, Valgerdur; Strawbridge, Rona J; Sung, Yun Ju; Tachmazidou, Ioanna; Tanaka, Toshiko; Thorleifsson, Gudmar; Trompet, Stella; Pervjakova, Natalia; Tyrer, Jonathan P; Vandenput, Liesbeth; van der Laan, Sander W; van der Velde, Nathalie; van Setten, Jessica; van Vliet-Ostaptchouk, Jana V; Verweij, Niek; Vlachopoulou, Efthymia; Waite, Lindsay L; Wang, Sophie R; Wang, Zhaoming; Wild, Sarah H; Willenborg, Christina; Wilson, James F; Wong, Andrew; Yang, Jian; Yengo, Loïc; Yerges-Armstrong, Laura M; Yu, Lei; Zhang, Weihua; Zhao, Jing Hua; Andersson, Ehm A; Bakker, Stephan J L; Baldassarre, Damiano; Banasik, Karina; Barcella, Matteo; Barlassina, Cristina; Bellis, Claire; Benaglio, Paola; Blangero, John; Blüher, Matthias; Bonnet, Fabrice; Bonnycastle, Lori L; Boyd, Heather A; Bruinenberg, Marcel; Buchman, Aron S; Campbell, Harry; Chen, Yii-Der Ida; Chines, Peter S; Claudi-Boehm, Simone; Cole, John; Collins, Francis S; de Geus, Eco J C; de Groot, Lisette C P G M; Dimitriou, Maria; Duan, Jubao; Enroth, Stefan; Eury, Elodie; Farmaki, Aliki-Eleni; Forouhi, Nita G; Friedrich, Nele; Gejman, Pablo V; Gigante, Bruna; Glorioso, Nicola; Go, Alan S; Gottesman, Omri; Gräßler, Jürgen; Grallert, Harald; Grarup, Niels; Gu, Yu-Mei; Broer, Linda; Ham, Annelies C; Hansen, Torben; Harris, Tamara B; Hartman, Catharina A; Hassinen, Maija; Hastie, Nicholas; Hattersley, Andrew T; Heath, Andrew C; Henders, Anjali K; Hernandez, Dena; Hillege, Hans; Holmen, Oddgeir; Hovingh, Kees G; Hui, Jennie; Husemoen, Lise L; Hutri-Kähönen, Nina; Hysi, Pirro G; Illig, Thomas; De Jager, Philip L; Jalilzadeh, Shapour; Jørgensen, Torben; Jukema, J Wouter; Juonala, Markus; Kanoni, Stavroula; Karaleftheri, Maria; Khaw, Kay Tee; Kinnunen, Leena; Kittner, Steven J; Koenig, Wolfgang; Kolcic, Ivana; Kovacs, Peter; Krarup, Nikolaj T; Kratzer, Wolfgang; Krüger, Janine; Kuh, Diana; Kumari, Meena; Kyriakou, Theodosios; Langenberg, Claudia; Lannfelt, Lars; Lanzani, Chiara; Lotay, Vaneet; Launer, Lenore J; Leander, Karin; Lindström, Jaana; Linneberg, Allan; Liu, Yan-Ping; Lobbens, Stéphane; Luben, Robert; Lyssenko, Valeriya; Männistö, Satu; Magnusson, Patrik K; McArdle, Wendy L; Menni, Cristina; Merger, Sigrun; Milani, Lili; Montgomery, Grant W; Morris, Andrew P; Narisu, Narisu; Nelis, Mari; Ong, Ken K; Palotie, Aarno; Pérusse, Louis; Pichler, Irene; Pilia, Maria G; Pouta, Anneli; Rheinberger, Myriam; Ribel-Madsen, Rasmus; Richards, Marcus; Rice, Kenneth M; Rice, Treva K; Rivolta, Carlo; Salomaa, Veikko; Sanders, Alan R; Sarzynski, Mark A; Scholtens, Salome; Scott, Robert A; Scott, William R; Sebert, Sylvain; Sengupta, Sebanti; Sennblad, Bengt; Seufferlein, Thomas; Silveira, Angela; Slagboom, P Eline; Smit, Jan H; Sparsø, Thomas H; Stirrups, Kathleen; Stolk, Ronald P; Stringham, Heather M; Swertz, Morris A; Swift, Amy J; Syvänen, Ann-Christine; Tan, Sian-Tsung

    2015-10-01

    Genome-wide association studies (GWAS) have identified more than 100 genetic variants contributing to BMI, a measure of body size, or waist-to-hip ratio (adjusted for BMI, WHRadjBMI), a measure of body shape. Body size and shape change as people grow older and these changes differ substantially between men and women. To systematically screen for age- and/or sex-specific effects of genetic variants on BMI and WHRadjBMI, we performed meta-analyses of 114 studies (up to 320,485 individuals of European descent) with genome-wide chip and/or Metabochip data by the Genetic Investigation of Anthropometric Traits (GIANT) Consortium. Each study tested the association of up to ~2.8M SNPs with BMI and WHRadjBMI in four strata (men ≤50y, men >50y, women ≤50y, women >50y) and summary statistics were combined in stratum-specific meta-analyses. We then screened for variants that showed age-specific effects (G x AGE), sex-specific effects (G x SEX) or age-specific effects that differed between men and women (G x AGE x SEX). For BMI, we identified 15 loci (11 previously established for main effects, four novel) that showed significant (FDR<5%) age-specific effects, of which 11 had larger effects in younger (<50y) than in older adults (≥50y). No sex-dependent effects were identified for BMI. For WHRadjBMI, we identified 44 loci (27 previously established for main effects, 17 novel) with sex-specific effects, of which 28 showed larger effects in women than in men, five showed larger effects in men than in women, and 11 showed opposite effects between sexes. No age-dependent effects were identified for WHRadjBMI. This is the first genome-wide interaction meta-analysis to report convincing evidence of age-dependent genetic effects on BMI. In addition, we confirm the sex-specificity of genetic effects on WHRadjBMI. These results may provide further insights into the biology that underlies weight change with age or the sexually dimorphism of body shape. PMID:26426971

  4. The Influence of Age and Sex on Genetic Associations with Adult Body Size and Shape: A Large-Scale Genome-Wide Interaction Study

    PubMed Central

    Feitosa, Mary F.; Chu, Su; Czajkowski, Jacek; Esko, Tõnu; Fall, Tove; Kilpeläinen, Tuomas O.; Lu, Yingchang; Mägi, Reedik; Mihailov, Evelin; Pers, Tune H.; Rüeger, Sina; Teumer, Alexander; Ehret, Georg B.; Ferreira, Teresa; Heard-Costa, Nancy L.; Karjalainen, Juha; Lagou, Vasiliki; Mahajan, Anubha; Neinast, Michael D.; Prokopenko, Inga; Simino, Jeannette; Teslovich, Tanya M.; Jansen, Rick; Westra, Harm-Jan; White, Charles C.; Absher, Devin; Ahluwalia, Tarunveer S.; Ahmad, Shafqat; Albrecht, Eva; Alves, Alexessander Couto; Bragg-Gresham, Jennifer L.; de Craen, Anton J. M.; Bis, Joshua C.; Bonnefond, Amélie; Boucher, Gabrielle; Cadby, Gemma; Cheng, Yu-Ching; Chiang, Charleston W. K.; Delgado, Graciela; Demirkan, Ayse; Dueker, Nicole; Eklund, Niina; Eiriksdottir, Gudny; Eriksson, Joel; Feenstra, Bjarke; Fischer, Krista; Frau, Francesca; Galesloot, Tessel E.; Geller, Frank; Goel, Anuj; Gorski, Mathias; Grammer, Tanja B.; Gustafsson, Stefan; Haitjema, Saskia; Hottenga, Jouke-Jan; Huffman, Jennifer E.; Jackson, Anne U.; Jacobs, Kevin B.; Johansson, Åsa; Kaakinen, Marika; Kleber, Marcus E.; Lahti, Jari; Leach, Irene Mateo; Lehne, Benjamin; Liu, Youfang; Lo, Ken Sin; Lorentzon, Mattias; Luan, Jian'an; Madden, Pamela A. F.; Mangino, Massimo; McKnight, Barbara; Medina-Gomez, Carolina; Monda, Keri L.; Montasser, May E.; Müller, Gabriele; Müller-Nurasyid, Martina; Nolte, Ilja M.; Panoutsopoulou, Kalliope; Pascoe, Laura; Paternoster, Lavinia; Rayner, Nigel W.; Renström, Frida; Rizzi, Federica; Rose, Lynda M.; Ryan, Kathy A.; Salo, Perttu; Sanna, Serena; Scharnagl, Hubert; Shi, Jianxin; Smith, Albert Vernon; Southam, Lorraine; Stančáková, Alena; Steinthorsdottir, Valgerdur; Strawbridge, Rona J.; Sung, Yun Ju; Tachmazidou, Ioanna; Tanaka, Toshiko; Thorleifsson, Gudmar; Trompet, Stella; Pervjakova, Natalia; Tyrer, Jonathan P.; Vandenput, Liesbeth; van der Laan, Sander W; van der Velde, Nathalie; van Setten, Jessica; van Vliet-Ostaptchouk, Jana V.; Verweij, Niek; Vlachopoulou, Efthymia; Waite, Lindsay L.; Wang, Sophie R.; Wang, Zhaoming; Wild, Sarah H.; Willenborg, Christina; Wilson, James F.; Wong, Andrew; Yang, Jian; Yengo, Loïc; Yerges-Armstrong, Laura M.; Yu, Lei; Zhang, Weihua; Zhao, Jing Hua; Andersson, Ehm A.; Bakker, Stephan J. L.; Baldassarre, Damiano; Banasik, Karina; Barcella, Matteo; Barlassina, Cristina; Bellis, Claire; Benaglio, Paola; Blangero, John; Blüher, Matthias; Bonnet, Fabrice; Bonnycastle, Lori L.; Boyd, Heather A.; Bruinenberg, Marcel; Buchman, Aron S; Campbell, Harry; Chen, Yii-Der Ida; Chines, Peter S.; Claudi-Boehm, Simone; Cole, John; Collins, Francis S.; de Geus, Eco J. C.; de Groot, Lisette C. P. G. M.; Dimitriou, Maria; Duan, Jubao; Enroth, Stefan; Eury, Elodie; Farmaki, Aliki-Eleni; Forouhi, Nita G.; Friedrich, Nele; Gejman, Pablo V.; Gigante, Bruna; Glorioso, Nicola; Go, Alan S.; Gottesman, Omri; Gräßler, Jürgen; Grallert, Harald; Grarup, Niels; Gu, Yu-Mei; Broer, Linda; Ham, Annelies C.; Hansen, Torben; Harris, Tamara B.; Hartman, Catharina A.; Hassinen, Maija; Hastie, Nicholas; Hattersley, Andrew T.; Heath, Andrew C.; Henders, Anjali K.; Hernandez, Dena; Hillege, Hans; Holmen, Oddgeir; Hovingh, Kees G; Hui, Jennie; Husemoen, Lise L.; Hutri-Kähönen, Nina; Hysi, Pirro G.; Illig, Thomas; De Jager, Philip L.; Jalilzadeh, Shapour; Jørgensen, Torben; Jukema, J. Wouter; Juonala, Markus; Kanoni, Stavroula; Karaleftheri, Maria; Khaw, Kay Tee; Kinnunen, Leena; Kittner, Steven J.; Koenig, Wolfgang; Kolcic, Ivana; Kovacs, Peter; Krarup, Nikolaj T.; Kratzer, Wolfgang; Krüger, Janine; Kuh, Diana; Kumari, Meena; Kyriakou, Theodosios; Langenberg, Claudia; Lannfelt, Lars; Lanzani, Chiara; Lotay, Vaneet; Launer, Lenore J.; Leander, Karin; Lindström, Jaana; Linneberg, Allan; Liu, Yan-Ping; Lobbens, Stéphane; Luben, Robert; Lyssenko, Valeriya; Männistö, Satu; Magnusson, Patrik K.; McArdle, Wendy L.; Menni, Cristina; Merger, Sigrun; Milani, Lili; Montgomery, Grant W.; Morris, Andrew P.; Narisu, Narisu; Nelis, Mari; Ong, Ken K.; Palotie, Aarno; Pérusse, Louis; Pichler, Irene; Pilia, Maria G.; Pouta, Anneli; Rheinberger, Myriam; Ribel-Madsen, Rasmus; Richards, Marcus; Rice, Kenneth M.; Rice, Treva K.; Rivolta, Carlo; Salomaa, Veikko; Sanders, Alan R.; Sarzynski, Mark A.; Scholtens, Salome; Scott, Robert A.; Scott, William R.; Sebert, Sylvain; Sengupta, Sebant