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Sample records for progeny sex ratio

  1. Sex ratio variation and sex determination in Urtica dioica

    NARCIS (Netherlands)

    Glawe, Grit Anja

    2006-01-01

    This thesis will first document on variation in progeny sex ratios among individual female plants of Urtica dioica at our field site in Meijendel (Chapter 2). Next, we show that there is also considerable sex ratio variation among male and female flowering shoots in 26 natural populations studied

  2. Sex Ratio Elasticity Influences the Selection of Sex Ratio Strategy

    Science.gov (United States)

    Wang, Yaqiang; Wang, Ruiwu; Li, Yaotang; (Sam) Ma, Zhanshan

    2016-12-01

    There are three sex ratio strategies (SRS) in nature—male-biased sex ratio, female-biased sex ratio and, equal sex ratio. It was R. A. Fisher who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton’s local mate competition (LMC) and Clark’s local resource competition (LRC) separately explained the observed deviations from the seemingly universal 1:1 ratio. However, to the best of our knowledge, there is not yet a unified theory that accounts for the mechanisms of the three SRS. Here, we introduce the price elasticity theory in economics to define sex ratio elasticity (SRE), and present an analytical model that derives three SRSs based on the following assumption: simultaneously existing competitions for both resources A and resources B influence the level of SRE in both sexes differently. Consequently, it is the difference (between two sexes) in the level of their sex ratio elasticity that leads to three different SRS. Our analytical results demonstrate that the elasticity-based model not only reveals a highly plausible mechanism that explains the evolution of SRS in nature, but also offers a novel framework for unifying two major classical theories (i.e., LMC & LRC) in the field of SRS research.

  3. The sex ratio at birth.

    Science.gov (United States)

    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.

  4. Inbreeding and parasite sex ratios.

    Science.gov (United States)

    Nee, Sean; West, Stuart A; Read, Andrew F

    2002-04-07

    The breeding system of parasitic protozoa affects the evolution of drug resistance and virulence, and is relevant to disease diagnosis and the development of chemo- and immunotherapy. A major group of protozoan parasites, the phylum Apicomplexa, that includes the aetiological agents of malaria, toxoplasmosis and coccidiosis, all have dimorphic sexual stages. The sex ratio (proportion of males produced by parasites) is predicted to depend upon the inbreeding rate, and it has been suggested that sex-ratio data offer a relatively cheap and easy method for indirectly estimating inbreeding rates. Here, we exploit a new theoretical machinery to show that there are generally valid relationships between f, Wright's coefficient of inbreeding, and sex ratio, z(*), the generality being with respect to population structure. To focus the discussion, we concentrate on malaria and show that the previously derived result, f = 1 - 2z(*), does not depend on the artificial assumptions about population structure that were previously made. Not only does this justify the use of sex ratio as an indirect measure of f, but also we argue that it may actually be preferable to measure f by measuring sex ratios, rather than by measuring departures from Hardy-Weinberg genotypic proportions both in malaria and parasites more generally.

  5. Inbreeding and parasite sex ratios

    OpenAIRE

    Nee, Sean; West, Stuart A; Read, Andrew F.

    2002-01-01

    The breeding system of parasitic protozoa affects the evolution of drug resistance and virulence, and is relevant to disease diagnosis and the development of chemo- and immunotherapy. A major group of protozoan parasites, the phylum Apicomplexa, that includes the aetiological agents of malaria, toxoplasmosis and coccidiosis, all have dimorphic sexual stages. The sex ratio (proportion of males produced by parasites) is predicted to depend upon the inbreeding rate, and it has been suggested tha...

  6. The evolution of sex ratios and sex-determining systems

    NARCIS (Netherlands)

    Uller, Tobias; Pen, Ido; Wapstra, Erik; Beukeboom, Leo W.; Komdeur, Jan

    Sex determination is a fundamental process governed by diverse mechanisms. Sex ratio selection is commonly implicated in the evolution of sex-determining systems, although formal models are rare. Here, we argue that, although sex ratio selection can induce shifts in sex determination, genomic

  7. Sex Determination, Sex Ratios, and Genetic Conflict

    NARCIS (Netherlands)

    Werren, John H.; Beukeboom, Leo W.

    1998-01-01

    Genetic mechanisms of sex determination are unexpectedly diverse and change rapidly during evolution. We review the role of genetic conflict as the driving force behind this diversity and turnover. Genetic conflict occurs when different components of a genetic system are subject to selection in

  8. Sex determination in beetles: Production of all male progeny by Parental RNAi knockdown of transformer

    Science.gov (United States)

    Shukla, Jayendra Nath; Palli, Subba Reddy

    2012-01-01

    Sex in insects is determined by a cascade of regulators ultimately controlling sex-specific splicing of a transcription factor, Doublesex (Dsx). We recently identified homolog of dsx in the red flour beetle, Tribolium castaneum (Tcdsx). Here, we report on the identification and characterization of a regulator of Tcdsx splicing in T. castaneum. Two male-specific and one female-specific isoforms of T. castaneum transformer (Tctra) were identified. RNA interference-aided knockdown of Tctra in pupa or adults caused a change in sex from females to males by diverting the splicing of Tcdsx pre-mRNA to male-specific isoform. All the pupa and adults developed from Tctra dsRNA injected final instar larvae showed male-specific sexually dimorphic structures. Tctra parental RNAi caused an elimination of females from the progeny resulting in production of all male progeny. Transformer parental RNAi could be used to produce all male population for use in pest control though sterile male release methods. PMID:22924109

  9. Criminalization of Homosexuality and Sex Ratios

    OpenAIRE

    Chang, Simon

    2015-01-01

    Sexual activities between consenting adults of the same sex are still criminalized in more than one third of the countries in the world despite a global wave of decriminalization in the past sixty years. This paper empirically investigates the effect of sex ratios, i.e. relative number of men to women, on the criminalization of same-sex sexual conducts. At the individual level, people in high sex ratio countries are found to be more hostile against homosexuality and the homosexuals than their...

  10. KINSHIP INSTITUTIONS AND SEX RATIOS IN INDIA

    National Research Council Canada - National Science Library

    TANIKA CHAKRABORTY; SUKKOO KIM

    2010-01-01

    .... 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...

  11. Determining sex ratios of turtle hatchlings

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Previous status assessments of marine turtles have assumed that the natural sex ratio of a marine turtle population is 1:1 (e.g. Conant et al. 2009). However, this...

  12. Maternal preconception diet and the sex ratio

    NARCIS (Netherlands)

    Cramer, J.S.; Lumey, L.H.

    2010-01-01

    Temporal variations in the sex ratio, or the ratio of boys to girls at birth, have been widely studied and variously attributed to social changes, conditions of war, and environmental changes. Recently, Mathews et al. ["You are what your mother eats: Evidence for maternal preconception diet

  13. Maternal preconception diet and the sex ratio

    NARCIS (Netherlands)

    Cramer, J.S.; Lumey, L.H.

    2009-01-01

    Temporal variations in the sex ratio or the ratio of boys over girls at birth have been widely studied and variously attributed to social changes, conditions of war, and environmental changes. Recently, Mathews, Johnson and Neil (2008) studied the direct evidence of individual pregnancies and

  14. PARTIALLY CONSTRAINED SEX ALLOCATION AND THE INDIRECT EFFECTS OF ASSISTED REPRODUCTIVE TECHNOLOGIES ON THE HUMAN SEX RATIO.

    Science.gov (United States)

    Hardy, Ian C W; Maalouf, Walid E

    2017-05-01

    Infertility affects around 15% of human couples and in many countries approximately 1-4% of babies are born following Assisted Reproductive Technologies (ART). Several ART techniques are used and these differentially affect the sex ratio of offspring successfully produced. These direct effects on sex ratio also have the potential to influence, indirectly, the sex ratios of offspring born to untreated couples. This is of concern because human sex ratio bias may adversely affect public health. Here the extent of indirect effects of ART that could operate, via Fisherian frequency-dependent natural selection, on the progeny sex ratio of unassisted members of a population is heuristically modelled. Given the degrees to which ART techniques bias sex ratios directly, it is predicted that well over 20% of couples would have to reproduce via ART for there to be any discernible effect on the sex ratios produced, in response, by the remainder of the population. This value is greater than the estimated prevalence of infertility problems among human couples. It is concluded that providing ART to couples with fertility problems does not currently generate significant ethical issues or public health concern in terms of indirect effects on the offspring sex ratios of untreated couples.

  15. Mother's occupation and sex ratio at birth.

    Science.gov (United States)

    Ruckstuhl, Kathreen E; Colijn, Grant P; Amiot, Volodymyr; Vinish, Erin

    2010-05-23

    Many women are working outside of the home, occupying a multitude of jobs with varying degrees of responsibilities and levels of psychological stress. We investigated whether different job types in women are associated with child sex at birth, with the hypothesis that women in job types, which are categorized as "high psychological stress" jobs, would be more likely to give birth to a daughter than a son, as females are less vulnerable to unfavourable conditions during conception, pregnancy and after parturition, and are less costly to carry to term. We investigated the effects of mother's age, maternal and paternal job type (and associated psychological stress levels) and paternal income on sex ratio at birth. Our analyses were based on 16,384 incidences of birth from a six-year (2000 to 2005 inclusive) childbirth dataset from Addenbrooke's Hospital in Cambridge, UK. We obtained a restricted data set from Addenbrooke's hospital with: maternal age, maternal and paternal occupations, and whether or not the child was first-born. Women in job types that were categorized as "high stress" were more likely to give birth to daughters, whereas women in job types that were categorized as "low stress" had equal sex ratios or a slight male bias in offspring. We also investigated whether maternal age, and her partner's income could be associated with reversed offspring sex ratio. We found no association between mother's age, her partner's job stress category or partner income on child sex. However, there was an important interaction between job stress category and partner income in some of the analyses. Partner income appears to attenuate the association between maternal job stress and sex ratios at moderate-income levels, and reverse it at high-income levels. To our knowledge this is the first report on the association between women's job type stress categories and offspring sex ratio in humans, and the potential mitigating effect of their partners' income.

  16. Mother's occupation and sex ratio at birth

    Directory of Open Access Journals (Sweden)

    Amiot Volodymyr

    2010-05-01

    Full Text Available Abstract Background Many women are working outside of the home, occupying a multitude of jobs with varying degrees of responsibilities and levels of psychological stress. We investigated whether different job types in women are associated with child sex at birth, with the hypothesis that women in job types, which are categorized as "high psychological stress" jobs, would be more likely to give birth to a daughter than a son, as females are less vulnerable to unfavourable conditions during conception, pregnancy and after parturition, and are less costly to carry to term. Methods We investigated the effects of mother's age, maternal and paternal job type (and associated psychological stress levels and paternal income on sex ratio at birth. Our analyses were based on 16,384 incidences of birth from a six-year (2000 to 2005 inclusive childbirth dataset from Addenbrooke's Hospital in Cambridge, UK. We obtained a restricted data set from Addenbrooke's hospital with: maternal age, maternal and paternal occupations, and whether or not the child was first-born. Results Women in job types that were categorized as "high stress" were more likely to give birth to daughters, whereas women in job types that were categorized as "low stress" had equal sex ratios or a slight male bias in offspring. We also investigated whether maternal age, and her partner's income could be associated with reversed offspring sex ratio. We found no association between mother's age, her partner's job stress category or partner income on child sex. However, there was an important interaction between job stress category and partner income in some of the analyses. Partner income appears to attenuate the association between maternal job stress and sex ratios at moderate-income levels, and reverse it at high-income levels. Conclusions To our knowledge this is the first report on the association between women's job type stress categories and offspring sex ratio in humans, and the

  17. Sex ratios at birth after induced abortion.

    Science.gov (United States)

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

    2016-06-14

    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. 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. 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. 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. © 2016 Canadian Medical Association or its licensors.

  18. Parental investment, sexual selection and sex ratios.

    Science.gov (United States)

    Kokko, Hanna; Jennions, Michael D

    2008-07-01

    Conventional sex roles imply caring females and competitive males. The evolution of sex role divergence is widely attributed to anisogamy initiating a self-reinforcing process. The initial asymmetry in pre-mating parental investment (eggs vs. sperm) is assumed to promote even greater divergence in post-mating parental investment (parental care). But do we really understand the process? Trivers [Sexual Selection and the Descent of Man 1871-1971 (1972), Aldine Press, Chicago] introduced two arguments with a female and male perspective on whether to care for offspring that try to link pre-mating and post-mating investment. Here we review their merits and subsequent theoretical developments. The first argument is that females are more committed than males to providing care because they stand to lose a greater initial investment. This, however, commits the 'Concorde Fallacy' as optimal decisions should depend on future pay-offs not past costs. Although the argument can be rephrased in terms of residual reproductive value when past investment affects future pay-offs, it remains weak. The factors likely to change future pay-offs seem to work against females providing more care than males. The second argument takes the reasonable premise that anisogamy produces a male-biased operational sex ratio (OSR) leading to males competing for mates. Male care is then predicted to be less likely to evolve as it consumes resources that could otherwise be used to increase competitiveness. However, given each offspring has precisely two genetic parents (the Fisher condition), a biased OSR generates frequency-dependent selection, analogous to Fisherian sex ratio selection, that favours increased parental investment by whichever sex faces more intense competition. Sex role divergence is therefore still an evolutionary conundrum. Here we review some possible solutions. Factors that promote conventional sex roles are sexual selection on males (but non-random variance in male mating success

  19. Offspring sex ratio of Iranian dentists.

    Science.gov (United States)

    Ghasemi, Hadi; Mirdehghan, Seyedeh Reihaneh; Namdari, Mahshid; Bayat, Fariborz

    2016-11-01

    To assess the impact of occupational factors on the sex ratio of dentists' children. A randomly selected 501 Iranian dentists participated in a telephone interview. The participants were contacted by their mobile number to answer questions about demographic variables (gender, age, marriage status), practice-related variables (year of graduation as general or specialist dentist, years of clinical work, working hours, average number of radiographs taken in a day, and spouse's job), and questions about their children (number, gender and date of birth of each child). Kruskal-Wallis and Chi-square tests served for statistical evaluation. Of all participating dentists, 71 % were men, about two-thirds were 35- to 50-year olds, and 89 % were married. In total, the dentists had 768 children; about 21 % had no child. Of all the children, 54 % were boys (overall sex ratio = 1.17). The offspring sex ratio was 1.13 among male dentists, 1.50 for female dentists, and 1.44 when both parents were dentists. Higher percentages of boys were prevalent among female dentists, younger dentists, and general dental practitioners (p dentists' children in this study. However, the result needs evaluation in further studies.

  20. Sex ratios in natural populations of Drosophila pseudoobscura from Mexico

    OpenAIRE

    Salceda Victor M.; Arceo-Maldonado Carolina

    2012-01-01

    Most species show an equal proportion of individuals of both sexes. In diploid species sex ratio is determined by a genic balance between sex chromosomes. In Drosophila sex is determined by the ratio of X- chromosomes versus autosomes and in some species of the genus it is related to the presence of an inversion in the sex chromosome. The present work analyses the sex ratio in 27 natural populations of Drosophila pseudoobscura that inhabit Mexico. Female fl...

  1. Tamil Nadu and the Diagonal Divide in Sex Ratios

    NARCIS (Netherlands)

    A.S. Bedi (Arjun Singh); S. Srinivasan (Sharada)

    2009-01-01

    textabstractBetween 1961 and 2001, India’s 0-6 sex ratio has steadily declined. Despite evidence to the contrary, this ratio is often characterised in terms of a diagonal divide with low 0-6 sex ratios in northern and western India and normal 0-6 sex ratios in eastern and southern India. While

  2. Effect of male densities on sex ratio variations of the predatory gall midge, Aphidoletes aphidimyza (Diptera: Cecidomyiidae

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Tabadkani

    2012-09-01

    Full Text Available Monogeny, the production of unisexual broods by individual females, is a well-known characteristic in several species of gall midges (Diptera: Cecidomyiidae. Theoretical models have proposed that monogeny may provide a system by which the arrhenogenic/thelygenic females can optionally raise or lower the number of their male/female eggs in response to changes in environmental conditions. In polygynous species, where the males mate with several females, a sex ratio bias toward females is expected to occur when environmental conditions such as food and temperature are suitable. In this paper, first, we evaluated the occurrence and intensity of monogeny in native populations of the polygynous predatory gall midge Aphidoletes aphidimyza. Then, we examined the sex ratio variations in relation to different densities of males in the populations. Two proportions of male gall midges (5 and 12 unmated males vs. 10 virgin females were obtained in plastic cages and the sex ratio of progenies was determined in each density. There was no difference between sex ratio of progenies when the females were exposed to high or low densities of males. Apparently, females cannot regulate the number of female-producing and/or male-producing progenies in response to male densities. Our results incline us to think about other benefits that may have been achieved through transition to monogeny.

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

    Science.gov (United States)

    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.

  4. Sex ratios of Mountain Plovers from egg production to fledging

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    Margaret M. Riordan

    2015-12-01

    Full Text Available Skewed sex ratios can have negative implications for population growth if they do not match a species' life history. A skewed tertiary sex ratio has been detected in a population of Mountain Plover (Charadrius montanus, a grassland shorebird experiencing population declines. To study the cause of the observed male skew, we examined three early life stages between egg and fledgling in eastern Colorado from 2010 to 2012. This allows us to distinguish between egg production and chick survival as an explanation for the observed skew. We examined the primary sex ratio in eggs produced and the secondary sex ratio in hatched chicks to see if the sex ratio bias occurs before hatching. We also determined the sex ratio at fledging to reveal sex-specific mortality of nestlings. The primary sex ratio was 1.01 (± 0.01 males per female. The secondary sex ratio consisted of 1.10 (± 0.02 males per female. The probability of a chick surviving to fledging differed between males (0.55 ± 0.13 and females (0.47 ± 0.15, but the precision of these survival estimates was low. Sex ratios in early life stages of the Mountain Plover do not explain the skewed sex ratio observed in adults in this breeding population.

  5. Computer-assisted sperm morphometry fluorescence-based analysis has potential to determine progeny sex

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    Pilar Santolaria

    2016-01-01

    Full Text Available This study was designed to determine the ability of computer-assisted sperm morphometry analysis (CASA-Morph with fluorescence to discriminate between spermatozoa carrying different sex chromosomes from the nuclear morphometrics generated and different statistical procedures in the bovine species. The study was divided into two experiments. The first was to study the morphometric differences between X- and Y-chromosome-bearing spermatozoa (SX and SY, respectively. Spermatozoa from eight bulls were processed to assess simultaneously the sex chromosome by FISH and sperm morphometry by fluorescence-based CASA-Morph. SX cells were larger than SY cells on average (P < 0.001 although with important differences between bulls. A simultaneous evaluation of all the measured features by discriminant analysis revealed that nuclear area and average fluorescence intensity were the variables selected by stepwise discriminant function analysis as the best discriminators between SX and SY. In the second experiment, the sperm nuclear morphometric results from CASA-Morph in nonsexed (mixed SX and SY and sexed (SX semen samples from four bulls were compared. FISH allowed a successful classification of spermatozoa according to their sex chromosome content. X-sexed spermatozoa displayed a larger size and fluorescence intensity than nonsexed spermatozoa (P < 0.05. We conclude that the CASA-Morph fluorescence-based method has the potential to find differences between X- and Y-chromosome-bearing spermatozoa in bovine species although more studies are needed to increase the precision of sex determination by this technique.

  6. Exploring the possibilities for stabilizing the sex ratio in India

    OpenAIRE

    Saurabh RamBihariLal Shrivastava; Prateek Saurabh Shrivastava; Jegadeesh Ramasamy

    2015-01-01

    The sex ratio is an important demographic indicator for a nation. A wide range of adverse social consequences have been observed because of a skewed sex ratio in India. If India as a nation is to achieve the Millennium Development Goal – 3 (which promotes gender equality and ensures the empowerment of women), the primary target should be involve all those involved, so that a collective and comprehensive approach can be developed to counter the public health menace of an asymmetrical sex ratio...

  7. Exploring the possibilities for stabilizing the sex ratio in India

    OpenAIRE

    Shrivastava, Saurabh; SHRIVASTAVA, Prateek; Ramasamy, Jegadeesh

    2016-01-01

    The sex ratio is an important demographic indicator for a nation. A wide range of adverse social consequences have been observed because of a skewed sex ratio in India. If India as a nation is to achieve the Millennium Development Goal – 3 (which promotes gender equality and ensures the empowerment of women), the primary target should be involve all those involved, so that a collective and comprehensive approach can be developed to counter the public health menace of an asymmetrical sex ratio...

  8. Local offspring density and sex ratio affect sex allocation in the great tit

    NARCIS (Netherlands)

    Michler, Stephanie P. M.; Nicolaus, Marion; van der Velde, Marco; Radersma, Reinder; Ubels, Richard; Both, Christiaan; Komdeur, Jan; Tinbergen, Joost M.

    2013-01-01

    The expected fitness gain for offspring of a given sex may depend on local population sex ratio and density. Knowing the influence of such social factors on brood sex ratios may contribute considerably to the understanding of sex allocation in higher vertebrates. For 3 consecutive years, we

  9. Effect of Temperature on Reproduction and Sex Ratio of Guppy (Poecilia reticulata Peters

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    H. Arfah

    2007-01-01

    Full Text Available Water temperature could affect the reproduction of broodstock and sex ratio of progeny.  In this study, broodstock of guppy (Poecilia reticulata Peters was reared in different temperature to determine its effect on reproduction of broodstock and sex ratio of their progeny. The result of study show that broodstock reared at 27°C produced more fry (16 males mean than that of 30°C (10 males, while broodstock reared at 33°C produced no progeny.  Percentage of male fish produced by broodstock reared at 30°C is higher than that of 27°C.  Incubation time of embryo before birth is sorter in broodstock reared at 30°C (4-12 days compared with 27°C (18-22 days.  However, several progeny of broodstock reared at 30°C had abnormal vertebrae. Keywords: guppy, Poecilia reticulata, sex reversal, reproduction, monosex   ABSTRAK Suhu air inkubasi diduga dapat mempengaruhi reproduksi induk ikan dan nisbah kelamin keturunannya.  Pada penelitian ini, induk ikan gapi (Poecilia reticulata Peters dipelihara pada suhu 27°C, 30°C dan suhu 33°C untuk mengetahui pengaruhnya terhadap reproduksi dan rasio kelamin keturunannya.  Hasil penelitian menunjukkan bahwa induk ikan gapi yang dipelihara pada suhu 27°C menghasilkan anak lebih banyak (rata-rata 16 ekor daripada di suhu 30°C (10 ekor, sementara induk gagal melahirkan pada suhu pemeliharaan 33°C. Proporsi anak jantan yang dihasilkan oleh induk yang dipelihara pada suhu 30°C lebih banyak dibandingkan pada suhu 27°C.  Waktu inkubasi embrio sebelum dilahirkan oleh induk yang dipelihara pada suhu 30°C lebih singkat, yaitu 4-12 hari, dibandingkan pada  suhu 27°C, 18-22 hari.  Namun demikian beberapa anak ikan yang lahir dari induk yang dipelihara pada suhu suhu 30°C mengalami abnormalitas pada bagian tulang belakangnya.  Kata kunci: ikan gapi, Poecilia reticulata, sex reversal, reproduksi, monoseks

  10. Effect of the Lebanese civil war on sex ratio.

    Science.gov (United States)

    Abu-Musa, Antoine; Usta, Ihab; Hannoun, Antoine; Nassar, Anwar

    2008-01-01

    Sex ratio is a subject of scientific interest but little is known about the factors that affect the sex ratio of humans. The aim of this study was to assess the effect of the Lebanese civil war on sex ratio. Data on all live births delivered at a large university hospital for the years 1977-2005 were used in this study. Study periods were defined as wartime (1977-1992) and post-war (1993-2005). The sex ratio in the study time period was calculated as the male proportion, i.e. males/males + females in live-born infants. Sex ratio during the war was compared with that of the post-war period. The sex ratio was similar in the war and post-war period (0.515 versus 0.513; OR = 1.007; 95% CI 0.98-1.04). The annual variation in the sex ratio during the study period did not show any significant change in any of the years. In conclusion, the Lebanese civil war did not cause a detectable change in sex ratio at birth. Factors that might have affected the sex ratio include the nature of the study population (civilians), the variable intensity of war in different periods, and the effect of stress and environmental toxins.

  11. Sex ratios in natural populations of Drosophila pseudoobscura from Mexico

    Directory of Open Access Journals (Sweden)

    Salceda Victor M.

    2012-01-01

    Full Text Available Most species show an equal proportion of individuals of both sexes. In diploid species sex ratio is determined by a genic balance between sex chromosomes. In Drosophila sex is determined by the ratio of X- chromosomes versus autosomes and in some species of the genus it is related to the presence of an inversion in the sex chromosome. The present work analyses the sex ratio in 27 natural populations of Drosophila pseudoobscura that inhabit Mexico. Female flies captured in nature were counted and their sex ratio calculated and been called generation P, then cultured individualy, allowed to leave adult offspring which was quantified in order to get its sex ratio and designated generation F1. sex ratio was calculated using the expression: number of males times 100 divided by the number of females proposed by Darwin (1871. The sex ratio of each population was taken using the average of all the individual counts from each sample. The values found varied among different generations and populations, so for generation P their values varieded 37.4 to 190.4 and in generation F1 from 31.3 up to 96.4 males for each 100 females. According to their geographical distribution four North to South transects were arranged and in them means varied from 60.8 to 81.7 males for each 100 females. All this means that in Mexican population are more females than males, exceptionally more males than females.

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

    OpenAIRE

    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 th...

  13. Do Workplace Sex Ratios Affect Partnership Formation and Dissolution?

    DEFF Research Database (Denmark)

    Svarer, Michael

    In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios are not ......In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios...... are not important for the overall transition rate from singlehood to partnership. The results suggest that the workplace constitutes a more important marriage market segment for individuals who are already in a partnership presumably due to higher search cost for (alternative) partners in general....

  14. Curious Sex Ratios and Cytoplasmic Genes Microbes Can Distort ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 6. Curious Sex Ratios and Cytoplasmic Genes Microbes Can Distort the Sex Ratio of Populations. Stephen J Freeland Laurence D Hurst. General Article Volume 2 Issue 6 June 1997 pp 68-78 ...

  15. Sex ratio distribution and fecundity of the claroteid catfish Clarotes ...

    African Journals Online (AJOL)

    Fecundity was estimated using gravimetric method. Differences in sex ratio distribution were statistically determined by Chi-square (x2), while relationship between length and fecundity, and length and weight were determined by multiple regression analysis. Sex ratio distribution varied greatly with respect to time and space ...

  16. Sex ratio, gonadal development and fecundity of the grunt ...

    African Journals Online (AJOL)

    The sex ratio, gonadosomatic index, stages of gonadal development and fecundity of the grunt, Pomadasys jubelini in the New Calabar-Bonny River were investigated. P. jubelini had a sex ratio of 1: 2.1 (male to female). Gonadosomatic index ranged from 0.33 to 7.29% with a mean of 2.89+0.08%. High gonadosomatic ...

  17. Exploring the possibilities for stabilizing the sex ratio in India

    Directory of Open Access Journals (Sweden)

    Saurabh RamBihariLal Shrivastava

    2015-12-01

    Full Text Available The sex ratio is an important demographic indicator for a nation. A wide range of adverse social consequences have been observed because of a skewed sex ratio in India. If India as a nation is to achieve the Millennium Development Goal – 3 (which promotes gender equality and ensures the empowerment of women, the primary target should be involve all those involved, so that a collective and comprehensive approach can be developed to counter the public health menace of an asymmetrical sex ratio. In conclusion, the nation’s program managers should prioritize the issue of a skewed sex ratio and work towards developing a coordinated response.Key Words: Sex ratio, policy makers, India.

  18. Sex Ratios Among Births in British Columbia, 2000-2013.

    Science.gov (United States)

    Joseph, K S; Lee, Lily; Williams, Kim

    2016-10-01

    Previous studies have reported distorted sex ratios among live births within specific immigrant groups in Canada. We carried out an investigation into sex ratios in British Columbia. All stillbirths and live births to residents of British Columbia from April 2000 to March 2013 were included in the study, with data obtained from the British Columbia Perinatal Data Registry. We examined sex ratios among births and among pregnancy terminations that resulted in a stillbirth or live birth. Analyses were stratified by congenital anomaly status, maternal residence, and parity. The study population included 567 225 stillbirths and live births. In the Fraser Health Authority, the sex ratio among births without congenital anomalies was 51.3% males (95% CI 51.1 to 51.5); this was significantly higher than the sex ratio of 40.7% males (95% CI 33.2 to 48.6) among late pregnancy terminations without congenital anomalies (P = 0.008). However, in British Columbia, excluding the Fraser Health Authority, the same sex ratios were 51.1% (95% CI 50.9 to 51.3) and 51.1% (95% CI 45.5 to 56.7), respectively (P = 0.99). Sex ratios among births to multiparous women were also significantly different in the Fraser Health Authority. Only a negligible fraction of the shortfall in female births in the Fraser Health Authority could be explained by sex ratio distortions among late pregnancy terminations. Sex ratios among stillbirths and live births to residents of the Fraser Health Authority are distorted relative to those observed elsewhere in British Columbia. This is likely due to sex differences in early pregnancy terminations. Copyright © 2016 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada. All rights reserved.

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

    NARCIS (Netherlands)

    Shyu, E.; Caswell, H.

    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

  20. Sex ratio selection and multi-factorial sex determination in the housefly : A dynamic model

    NARCIS (Netherlands)

    Kozielska, M.A.; Pen, I.R.; Beukeboom, L.W.; Weissing, F.J.

    Sex determining (SD) mechanisms are highly variable between different taxonomic groups and appear to change relatively quickly during evolution. Sex ratio selection could be a dominant force causing such changes. We investigate theoretically the effect of sex ratio selection on the dynamics of a

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

    Energy Technology Data Exchange (ETDEWEB)

    Heuther, C.A.; Martin, R.L.M.; Stoppelman, S.M. [Univ. of Cincinnati, OH (United States)] [and others

    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.

  2. Psychological distress during early gestation and offspring sex ratio

    DEFF Research Database (Denmark)

    Obel, Carsten; Henriksen, Tine Brink; Secher, Niels Jørgen

    2007-01-01

    BACKGROUND: Exposure to severe stress in early pregnancy is associated with a lower male to female ratio (sex ratio), but whether more moderate levels of psychological discomfort have the same kind of effect is unknown. In a population based follow-up study, we aimed to test whether psychological...... suggest that not only severe stress, but also more moderate and common levels of psychological distress, may decrease the sex ratio in the offspring. Stress during pregnancy is a likely candidate involved in the decreasing sex ratio observed in many countries. Udgivelsesdato: 2007-Nov...... distress was associated with the sex ratio in the offspring. METHODS: From 1989 to 1992, a cohort of 8,719 Danish-speaking pregnant women were followed until delivery. Questionnaires were administered to the women in early pregnancy and 6,629 (76%) completed the 30-item version of the General Health...

  3. Psychological distress during early gestation and offspring sex ratio

    DEFF Research Database (Denmark)

    Obel, C; Henriksen, TB; Secher, Niels Jørgen

    2007-01-01

    BACKGROUND: Exposure to severe stress in early pregnancy is associated with a lower male to female ratio (sex ratio), but whether more moderate levels of psychological discomfort have the same kind of effect is unknown. In a population based follow-up study, we aimed to test whether psychological...... suggest that not only severe stress, but also more moderate and common levels of psychological distress, may decrease the sex ratio in the offspring. Stress during pregnancy is a likely candidate involved in the decreasing sex ratio observed in many countries....... distress was associated with the sex ratio in the offspring. METHODS: From 1989 to 1992, a cohort of 8,719 Danish-speaking pregnant women were followed until delivery. Questionnaires were administered to the women in early pregnancy and 6,629 (76%) completed the 30-item version of the General Health...

  4. Extraordinary sex ratios: cultural effects on ecological consequences.

    Directory of Open Access Journals (Sweden)

    Ferenc Molnár

    Full Text Available We model sex-structured population dynamics to analyze pairwise competition between groups differing both genetically and culturally. A sex-ratio allele is expressed in the heterogametic sex only, so that assumptions of Fisher's analysis do not apply. Sex-ratio evolution drives cultural evolution of a group-associated trait governing mortality in the homogametic sex. The two-sex dynamics under resource limitation induces a strong Allee effect that depends on both sex ratio and cultural trait values. We describe the resulting threshold, separating extinction from positive growth, as a function of female and male densities. When initial conditions avoid extinction due to the Allee effect, different sex ratios cannot coexist; in our model, greater female allocation always invades and excludes a lesser allocation. But the culturally transmitted trait interacts with the sex ratio to determine the ecological consequences of successful invasion. The invading female allocation may permit population persistence at self-regulated equilibrium. For this case, the resident culture may be excluded, or may coexist with the invader culture. That is, a single sex-ratio allele in females and a cultural dimorphism in male mortality can persist; a low-mortality resident trait is maintained by father-to-son cultural transmission. Otherwise, the successfully invading female allocation excludes the resident allele and culture and then drives the population to extinction via a shortage of males. Finally, we show that the results obtained under homogeneous mixing hold, with caveats, in a spatially explicit model with local mating and diffusive dispersal in both sexes.

  5. Nestling sex ratio in the Southwestern Willow Flycatcher

    Science.gov (United States)

    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.

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

    OpenAIRE

    Paulino eMartínez; Ana eViñas; Laura eSánchez; Noelia eDíaz; Laia eRibas; Francesc ePiferrer

    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 conveni...

  7. Child underreporting, fertility, and sex ratio imbalance in China.

    Science.gov (United States)

    Goodkind, Daniel

    2011-02-01

    Child underreporting is often neglected in studies of fertility and sex ratio imbalance in China. To improve estimates of these measures, I use intercensal comparisons to identify a rise in underreporting, which followed the increased enforcement and penalization under the birth planning system in 1991. A new triangulation of evidence indicates that about 19% of children at ages 0-4 were unreported in the 2000 census, more than double that of the 1990 census. This evidence contradicts assumptions underlying the fertility estimates of most recent studies. Yet, the analysis also suggests that China's fertility in the late 1990s (and perhaps beyond) was below officially adjusted levels. I then conduct a similar intercensal analysis of sex ratios of births and children, which are the world's highest primarily because of prenatal sex selection. However, given excess underreporting of young daughters, especially pronounced just after 1990, estimated ratios are lower than reported ratios. Sex ratios in areas with a "1.5-child" policy are especially distorted because of excess daughter underreporting, as well as sex-linked stopping rules and other factors, although it is unclear whether such policies increase use of prenatal sex selection. China's sex ratio at birth, once it is standardized by birth order, fell between 2000 and 2005 and showed a continuing excess in urban China, not rural China.

  8. Should sex-ratio distorting parasites abandon horizontal transmission?

    Science.gov (United States)

    2011-01-01

    Background Sex-ratio distorting parasites are of interest due to their effects upon host population dynamics and their potential to influence the evolution of host sex determination systems. In theory, the ability to distort host sex-ratios allows a parasite with efficient vertical (hereditary) transmission to dispense completely with horizontal (infectious) transmission. However, recent empirical studies indicate that some sex-ratio distorting parasites have retained the capability for horizontal transmission. Results Numerical simulations using biologically realistic parameters suggest that a feminising parasite is only likely to lose the capability for horizontal transmission if its host occurs at low density and/or has a male-biased primary sex ratio. It is also demonstrated that even a small amount of horizontal transmission can allow multiple feminising parasites to coexist within a single host population. Finally it is shown that, by boosting its host's rate of population growth, a feminising parasite can increase its own horizontal transmission and allow the invasion of other, more virulent parasites. Conclusions The prediction that sex-ratio distorting parasites are likely to retain a degree of horizontal transmission has important implications for the epidemiology and host-parasite interactions of these organisms. It may also explain the frequent co-occurrence of several sex-ratio distorting parasite species in nature. PMID:22188680

  9. Should sex-ratio distorting parasites abandon horizontal transmission?

    Directory of Open Access Journals (Sweden)

    Ironside Joseph E

    2011-12-01

    Full Text Available Abstract Background Sex-ratio distorting parasites are of interest due to their effects upon host population dynamics and their potential to influence the evolution of host sex determination systems. In theory, the ability to distort host sex-ratios allows a parasite with efficient vertical (hereditary transmission to dispense completely with horizontal (infectious transmission. However, recent empirical studies indicate that some sex-ratio distorting parasites have retained the capability for horizontal transmission. Results Numerical simulations using biologically realistic parameters suggest that a feminising parasite is only likely to lose the capability for horizontal transmission if its host occurs at low density and/or has a male-biased primary sex ratio. It is also demonstrated that even a small amount of horizontal transmission can allow multiple feminising parasites to coexist within a single host population. Finally it is shown that, by boosting its host's rate of population growth, a feminising parasite can increase its own horizontal transmission and allow the invasion of other, more virulent parasites. Conclusions The prediction that sex-ratio distorting parasites are likely to retain a degree of horizontal transmission has important implications for the epidemiology and host-parasite interactions of these organisms. It may also explain the frequent co-occurrence of several sex-ratio distorting parasite species in nature.

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

    Science.gov (United States)

    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.

  11. Ambient temperature predicts sex ratios and male longevity

    OpenAIRE

    Catalano, Ralph; Bruckner, Tim; SMITH, KIRK R.

    2008-01-01

    The theory that natural selection has conserved mechanisms by which women subjected to environmental stressors abort frail male fetuses implies that climate change may affect sex ratio at birth and male longevity. Using time series methods, we find that cold ambient temperatures during gestation predict lower secondary sex ratios and longer life span of males in annual birth cohorts composed of Danes, Finns, Norwegians, and Swedes born between 1878 (earliest year with complete life tables) an...

  12. Sex ratio comparisons between nestlings and dead embryos of the Sparrowhawk Accipiter nisus

    NARCIS (Netherlands)

    Burg, Van den A.B.; Diermen, Van J.; Müskens, G.J.D.M.; Rijn, van S.; Zollinger, R.

    2002-01-01

    Sex ratios that differ from unity have been reported for several bird species, but are poorly understood. Skewed sex ratios may originate at ovulation (primary sex ratio) or arise through differential mortality between the sexes (secondary sex ratio). To estimate the primary sex ratio from nestlings

  13. Breeding sex ratios in adult leatherback turtles (Dermochelys coriacea) may compensate for female-biased hatchling sex ratios.

    Science.gov (United States)

    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.

  14. Breeding sex ratios in adult leatherback turtles (Dermochelys coriacea may compensate for female-biased hatchling sex ratios.

    Directory of Open Access Journals (Sweden)

    Kelly R Stewart

    Full Text Available 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.

  15. Offspring sex ratio bias and sex related characteristics of eggs in chicken

    NARCIS (Netherlands)

    Aslam, M.A.

    2014-01-01

    Understanding the factors influencing sex of egg and sex ratio in laying chicken may lead to finding potential solutions for the problem of killing of day old male chicks, which is the current practice in breeding of laying hens. In studies described in this thesis, it was investigated if the sex of

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

    Science.gov (United States)

    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. © 2016 The Author(s).

  17. Factors influencing the optimum sex ratio in a structured population.

    Science.gov (United States)

    Nunney, L; Luck, R F

    1988-02-01

    W. D. Hamilton (1967, Science 156, 477-488) calculated the optimum sex-ratio strategy for a population subdivided into local mating groups. He made three important assumptions: that the females founding each group responded precisely to the number of them initiating the group; that ail broods within a group matured synchronously; and that males were incapable of dispersing between groups. We have examined the effects of relaxing each of these assumptions and obtained the following results: (1) When broods mature asynchronously the optimum sex ratio is considerably more female biased than the Hamiltonian prediction. (2) Increasing male dispersal always decreases the optimum female bias to the sex ratio, but it is of particular interest that when moderate levels of dispersal are coupled with asynchrony of brood maturation then the optimum strategy is relatively insensitive to changes in foundress number. (3) When females cannot precisely determine the number of other foundresses initiating the group then the optimum strategy is almost exactly the strategy appropriate to a group of average size. These effects can be most easily understood in terms of local parental control (LPC) of the sex ratio. Through LPC a founding female can alter the mating success of her sons by altering the sex ratio of her brood. Asynchrony in the maturation of broods within a group increases the control that a founding female has over the mating success of her sons, whereas male dispersal reduces it. We have shown that the role of LPC and the role of inbreeding, which favors a female-biased sex ratio in haploidiploid species, are independent and that their effects can be combined into a single general formula r = (1-(r2/z2) E(alpha z/alpha r]/(1 + I). The concept of LPC can also be used to interpret two factors which have been proposed to select for the Hamiltonian sex ratios: local mate competition is LPC acting through sons; and sib mating is LPC acting through daughters.

  18. Sex choice in plants: facultative adjustment of the sex ratio in the perennial herb Begonia gracilis.

    Science.gov (United States)

    López, S; Domínguez, C A

    2003-11-01

    Sex allocation theory predicts that reproducing individuals will increase their fitness by facultatively adjusting their relative investment towards the rarer sex in response to population shifts in operational sex ratio (OSR). The evolution of facultative manipulation of sex ratio depends on the ability of the parents to track the conditions favouring skewed sex allocation and on the mechanism controlling sex allocation. In animals, which have well-developed sensorial mechanisms, facultative adjustment of sex ratios has been demonstrated on many occasions. In this paper, we show that plants have mechanisms that allow them to evaluate the population OSR. We simulated three different conditions of population OSR by manipulating the amount of pollen received by the female flowers of a monoecious herb, and examined the effect of this treatment on the allocation to male vs. female flowers. A shortage of pollen on the stigmas resulted in a more male-skewed sex allocation, whereas plants that experienced a relatively pollen rich environment tended to produce a more female-skewed sex allocation pattern. Our results for Begonia gracilis demonstrate that the individuals of this species are able to respond to the levels of pollination intensity experienced by their female flowers and adjust their patterns of sex allocation in accordance to the expectations of sex allocation theory.

  19. Sex reversal and primary sex ratios in the common frog (Rana temporaria).

    Science.gov (United States)

    Alho, Jussi S; Matsuba, Chikako; Merilä, Juha

    2010-05-01

    Sex reversal has been suggested to have profound implications for the evolution of sex chromosomes and population dynamics in ectotherms. Occasional sex reversal of genetic males has been hypothesized to prevent the evolutionary decay of nonrecombining Y chromosomes caused by the accumulation of deleterious mutations. At the same time, sex reversals can have a negative effect on population growth rate. Here, we studied phenotypic and genotypic sex in the common frog (Rana temporaria) in a subarctic environment, where strongly female-biased sex ratios have raised the possibility of frequent sex reversals. We developed two novel sex-linked microsatellite markers for the species and used them with a third, existing marker and a Bayesian modelling approach to study the occurrence of sex reversal and to determine primary sex ratios in egg clutches. Our results show that a significant proportion (0.09, 95% credible interval: 0.04-0.18) of adults that were genetically female expressed the male phenotype, but there was no evidence of sex reversal of genetic males that is required for counteracting the degeneration of Y chromosome. The primary sex ratios were mostly equal, but three clutches consisted only of genetic females and three others had a significant female bias. Reproduction of the sex-reversed genetic females appears to create all-female clutches potentially skewing the population level adult sex-ratio consistent with field observations. However, based on a simulation model, such a bias is expected to be small and transient and thus does not fully explain the observed female-bias in the field.

  20. Ambient temperature predicts sex ratios and male longevity.

    Science.gov (United States)

    Catalano, Ralph; Bruckner, Tim; Smith, Kirk R

    2008-02-12

    The theory that natural selection has conserved mechanisms by which women subjected to environmental stressors abort frail male fetuses implies that climate change may affect sex ratio at birth and male longevity. Using time series methods, we find that cold ambient temperatures during gestation predict lower secondary sex ratios and longer life span of males in annual birth cohorts composed of Danes, Finns, Norwegians, and Swedes born between 1878 (earliest year with complete life tables) and 1914 (last birth cohort for which male life span can be estimated). We conclude that ambient temperature affects the characteristics of human populations by influencing who survives gestation, a heretofore unrecognized effect of climate on humanity.

  1. Sex roles and adult sex ratios: insights from mammalian biology and consequences for primate behaviour.

    Science.gov (United States)

    Kappeler, Peter M

    2017-09-19

    Theoretical models and empirical studies in various taxa have identified important links between variation in sex roles and the number of adult males and females (adult sex ratio (ASR)) in a population. In this review, I examine these relationships in non-human primates. Because most existing theoretical models of the evolution of sex roles focus on the evolutionary origins of sex-biased behaviour, they offer only a general scaffold for predicting variation in sex roles among and within species. I argue that studies examining sex role variation at these more specific levels need to take social organization into account to identify meaningful levels for the measurement of ASR and to account for the fact that ASR and sex roles mutually influence each other. Moreover, taxon-specific life-history traits can constrain sex role flexibility and impact the operational sex ratio (OSR) by specifying the minimum length of female time outs from reproduction. Using examples from the primate literature, I highlight practical problems in estimating ASR and OSR. I then argue that interspecific variation in the occurrence of indirect forms of paternal care might indeed be linked to variation in ASR. Some studies also indicate that female aggression and bonding, as well as components of inter-sexual relationships, are sensitive to variation in ASR. Thus, links between primate sex roles and sex ratios merit further study, and such studies could prompt the development of more specific theoretical models that make realistic assumptions about taxon-specific life history and social organization.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

  2. India’s Distorted Sex Ratio: Dire Consequences for Girls

    Science.gov (United States)

    Roberts, Lisa R.; Montgomery, Susanne B.

    2017-01-01

    Female gender discrimination related to cultural preference for males is a common global problem, especially in Asian countries. Numerous laws intended to prevent discrimination on the basis of gender have been passed in India, yet the distorted female-to-male sex ratio seems to show worsening tendencies. Using detailed, two-year longitudinal chart abstraction data about delivery records of a private mission hospital in rural India, we explored if hospital birth ratio data differed in comparison to regional data, and what demographic and contextual variables may have influenced these outcomes. Using quantitative chart abstraction and qualitative contextual data, study results showed the female-to-male ratio was lower than the reported state ratio at birth. In the context of India’s patriarchal structure, with its strong son preference, women are under tremendous pressure or coerced to access community-based, sex-selective identification and female fetus abortion. Nurses may be key to turning the tide. PMID:28286369

  3. India's Distorted Sex Ratio: Dire Consequences for Girls.

    Science.gov (United States)

    Roberts, Lisa R; Montgomery, Susanne B

    2016-01-01

    Female gender discrimination related to cultural preference for males is a common global problem, especially in Asian countries. Numerous laws intended to prevent discrimination on the basis of gender have been passed in India, yet the distorted female-to-male sex ratio seems to show worsening tendencies. Using detailed, two-year longitudinal chart abstraction data about delivery records of a private mission hospital in rural India, we explored if hospital birth ratio data differed in comparison to regional data, and what demographic and contextual variables may have influenced these outcomes. Using quantitative chart abstraction and qualitative contextual data, study results showed the female-to-male ratio was lower than the reported state ratio at birth. In the context of India's patriarchal structure, with its strong son preference, women are under tremendous pressure or coerced to access community-based, sex-selective identification and female fetus abortion. Nurses may be key to turning the tide.

  4. India?s Distorted Sex Ratio: Dire Consequences for Girls

    OpenAIRE

    Roberts, Lisa R.; Montgomery, Susanne B.

    2016-01-01

    Female gender discrimination related to cultural preference for males is a common global problem, especially in Asian countries. Numerous laws intended to prevent discrimination on the basis of gender have been passed in India, yet the distorted female-to-male sex ratio seems to show worsening tendencies. Using detailed, two-year longitudinal chart abstraction data about delivery records of a private mission hospital in rural India, we explored if hospital birth ratio data differed in compari...

  5. Sex ratio of lambs born from assisted reproductive technologies

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-18

    Aug 18, 2009 ... Key words: Sex ratio, assisted reproductive technologies, sheep. INTRODUCTION. Assisted reproductive technologies, including artificial in- semination (AI) and embryo transfer (ET) have developed into powerful reproductive flock management techniques. Currently, AI alone, or in combination with an ET.

  6. Length Frequency Distribution And Sex Ratio Of Macrobrachium ...

    African Journals Online (AJOL)

    Length frequency distribution and sex ratio of Macrobrachium macrobrachion sampled by cane traps in the Lagos –Lekki lagoon system were estimated from May 2002 to April 2004. The total number of size classes for the first and second year for both male and female ranged from 10 – 12. The length range was 3 to 14cm ...

  7. Sex ratio of lambs born from assisted reproductive technologies ...

    African Journals Online (AJOL)

    The objective of the present study was to investigate sex ratio of offspring resulting from superstimulated donors from two different breeds and artificially inseminated ewes from three different breeds. Romanov (n = 5) and Charollais (n = 6) (2 - 7 years of age) donors were superovulated using FSH-p with 400 mg ...

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

    Science.gov (United States)

    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.

  9. Sex Ratio Bias Leads to the Evolution of Sex Role Reversal in Honey Locust Beetles.

    Science.gov (United States)

    Fritzsche, Karoline; Booksmythe, Isobel; Arnqvist, Göran

    2016-09-26

    The reversal of conventional sex roles was enigmatic to Darwin, who suggested that it may evolve when sex ratios are female biased [1]. Here we present direct evidence confirming Darwin's hypothesis. We investigated mating system evolution in a sex-role-reversed beetle (Megabruchidius dorsalis) using experimental evolution under manipulated sex ratios and food regimes. In female-biased populations, where reproductive competition among females was intensified, females evolved to be more attractive and the sex roles became more reversed. Interestingly, female-specific mating behavior evolved more rapidly than male-specific mating behavior. We show that sexual selection due to reproductive competition can be strong in females and can target much the same traits as in males of species with conventional mating systems. Our study highlights two central points: the role of ecology in directing sexual selection and the role that females play in mating system evolution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Sex ratio adjustment by sex-specific maternal cannibalism in hamsters.

    Science.gov (United States)

    Beery, Annaliese K; Zucker, Irving

    2012-10-10

    Mammalian offspring sex ratios can be biased via prenatal and postnatal mechanisms, including sperm selection, sex-specific embryo loss, and differential postnatal investment in males and females. Syrian hamsters routinely cannibalize some of their pups in the first days after birth. We present evidence that short day lengths, typically predictive of poor autumn and winter field conditions, are associated with male-biased sex ratios, achieved in part through selective perinatal maternal infanticide of female offspring. Higher peak litter sizes were associated with increased cannibalism rates, decreased final litter counts, and increased body mass of pups surviving to weaning. To our knowledge this is the first report of sex ratio adjustment by offspring cannibalism. Copyright © 2012 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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.

  12. Recent increase in sex ratio at birth in Viet Nam.

    Directory of Open Access Journals (Sweden)

    Christophe Z Guilmoto

    Full Text Available INTRODUCTION: Since the 1980s, sex ratio at birth (male births per 100 female births has increased in many Asian countries as a result of selective abortions, but to date there has been no such evidence for Viet Nam. Our aim in this paper is to ascertain the situation with respect to sex ratio at birth in Viet Nam over the past five years. MATERIALS AND METHODS: Original data were obtained from sample population surveys in Viet Nam recording annual birth rates since 2000 of about 450,000 women, as well as from two successive birth surveys conducted for the first time in 2007 (1.1 million births. The annual population surveys include specific information on birth history and mothers' characteristics to be used for the analysis of trends and differentials in sex ratio at birth. RESULTS AND DISCUSSION: Birth history statistics indicate that the SRB in Viet Nam has recorded a steady growth since 2001. Starting from a level probably close to the biological standard of 105, the SRB reached 108 in 2005 and 112 in 2006, a value significantly above the normal level. An independent confirmation of these results comes from the surveys of births in health facilities which yielded a SRB of 110 in 2006-07. High SRB is linked to various factors such as access to modern health care, number of prenatal visits, level of higher education and employment status, young age, province of residence and prenatal sex determination. These results suggest that prenatal sex determination followed by selective abortion has recently become more common in Viet Nam. This recent trend is a consequence of various factors such as preference for sons, declining fertility, easy access to abortion, economic development as well as the increased availability of ultrasonography facilities.

  13. Population viability at extreme sex-ratio skews produced by temperature-dependent sex determination.

    Science.gov (United States)

    Hays, Graeme C; Mazaris, Antonios D; Schofield, Gail; Laloë, Jacques-Olivier

    2017-02-08

    For species with temperature-dependent sex determination (TSD) there is the fear that rising temperatures may lead to single-sex populations and population extinction. We show that for sea turtles, a major group exhibiting TSD, these concerns are currently unfounded but may become important under extreme climate warming scenarios. We show how highly female-biased sex ratios in developing eggs translate into much more balanced operational sex ratios so that adult male numbers in populations around the world are unlikely to be limiting. Rather than reducing population viability, female-biased offspring sex ratios may, to some extent, help population growth by increasing the number of breeding females and hence egg production. For rookeries across the world (n = 75 sites for seven species), we show that extreme female-biased hatchling sex ratios do not compromise population size and are the norm, with a tendency for populations to maximize the number of female hatchlings. Only at extremely high incubation temperature does high mortality within developing clutches threaten sea turtles. Our work shows how TSD itself is a robust strategy up to a point, but eventually high mortality and female-only hatchling production will cause extinction if incubation conditions warm considerably in the future. © 2017 The Author(s).

  14. Population sex ratios: another consideration in the reintroduction - reinforcement debate?

    Directory of Open Access Journals (Sweden)

    Sergio A Lambertucci

    Full Text Available Reintroduction or reinforcement (RorR of wild populations is a common conservation strategy. Many conservation projects involve the release of individuals of poorly studied species. This may lead to inefficient results or negative impacts on the conservation efforts. Here, we provide new insights into the conservation implications and potential consequences of a skew in the sex ratio of released birds and of the number of birds supplemented for the demography of a long-lived dimorphic bird species, the Andean condor (Vulturgryphus. We demonstrate that a RorR conservation program may be less effective in conserving a species if the sex ratios of the releases and the recipient populations are not considered. We also show that releases can reduce population declines but only if carried out over long periods (i.e., several decades. This can mean high costs for release programs and the added challenge of maintaining programs over time. If RorR programs are to be implemented, bearing in mind the importance of properly assessing their effectiveness, we urge conservation researchers and managers to consider the implications of sex ratio biases for wild populations, and particularly for dimorphic species with sexually despotic behaviour.

  15. A predictive relationship between population and genetic sex ratios in clonal species

    Science.gov (United States)

    McLetchie, D. Nicholas; García-Ramos, Gisela

    2017-04-01

    Sexual reproduction depends on mate availability that is reflected by local sex ratios. In species where both sexes can clonally expand, the population sex ratio describes the proportion of males, including clonally derived individuals (ramets) in addition to sexually produced individuals (genets). In contrast to population sex ratio that accounts for the overall abundance of the sexes, the genetic sex ratio reflects the relative abundance of genetically unique mates, which is critical in predicting effective population size but is difficult to estimate in the field. While an intuitive positive relationship between population (ramet) sex ratio and genetic (genet) sex ratio is expected, an explicit relationship is unknown. In this study, we determined a mathematical expression in the form of a hyperbola that encompasses a linear to a nonlinear positive relationship between ramet and genet sex ratios. As expected when both sexes clonally have equal number of ramets per genet both sex ratios are identical, and thus ramet sex ratio becomes a linear function of genet sex ratio. Conversely, if sex differences in ramet number occur, this mathematical relationship becomes nonlinear and a discrepancy between the sex ratios amplifies from extreme sex ratios values towards intermediate values. We evaluated our predictions with empirical data that simultaneously quantified ramet and genet sex ratios in populations of several species. We found that the data support the predicted positive nonlinear relationship, indicating sex differences in ramet number across populations. However, some data may also fit the null model, which suggests that sex differences in ramet number were not extensive, or the number of populations was too small to capture the curvature of the nonlinear relationship. Data with lack of fit suggest the presence of factors capable of weakening the positive relationship between the sex ratios. Advantages of this model include predicting genet sex ratio using

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

    Science.gov (United States)

    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.

  17. Could changes in reported sex ratios at birth during China's 1958-1961 famine support the adaptive sex ratio adjustment hypothesis?

    Directory of Open Access Journals (Sweden)

    Anna Reimondos

    2013-10-01

    Full Text Available Background: The adaptive sex ratio adjustment hypothesis suggests that when mothers are in poor conditions the sex ratio of their offspring will be biased towards females. Major famines provide opportunities for testing this hypothesis because they lead to the widespread deterioration of living conditions in the affected population. Objective: This study examines changes in sex ratio at birth before, during, and after China's 1958-1961 famine, to see whether they provide any support for the adaptive sex ratio adjustment hypothesis. Methods: We use descriptive statistics to analyse data collected by both China's 1982 and 1988 fertility sample surveys and examine changes in sex ratio at birth in recent history. In addition, we examine the effectiveness of using different methods to model changes in sex ratio at birth and compare their differences. Results: During China's 1958-1961 famine, reported sex ratio at birth remained notably higher than that observed in most countries in the world. The timing of the decline in sex ratio at birth did not coincide with the timing of the famine. After the famine, although living conditions were considerably improved, the sex ratio at birth was not higher but lower than that recorded during the famine. Conclusions: The analysis of the data collected by the two fertility surveys has found no evidence that changes in sex ratio at birth during China's 1958-1961 famine and the post-famine period supported the adaptive sex ratio adjustment hypothesis.

  18. The effect of climate fluctuation on chimpanzee birth sex ratio.

    Directory of Open Access Journals (Sweden)

    Hjalmar S Kühl

    Full Text Available 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.

  19. Bare market: campus sex ratios, romantic relationships, and sexual behavior.

    Science.gov (United States)

    Uecker, Jeremy E; Regnerus, Mark D

    2010-01-01

    Using a nationally representative sample of college women, we evaluate the effect of campus sex ratios on women's relationship attitudes and behaviors. Our results suggest that women on campuses where they comprise a higher proportion of the student body give more negative appraisals of campus men and relationships, go on fewer traditional dates, are less likely to have had a college boyfriend, and are more likely to be sexually active. These effects appear to stem both from decreased dyadic power among women on campuses where they are more numerous and from their increased difficulty locating a partner on such campuses.

  20. Exploring racial variations in the spousal sex ratio of killing.

    Science.gov (United States)

    Regoeczi, W C

    2001-12-01

    The following article examines differences in the social situation of intimate partners as an explanation of racial differences in the female to male ratio of spousal homicides in Canada. An analysis of homicide data from 1961 to 1983 generated by the Canadian Centre for Justice Statistics reveals that the ratio of women killing their husbands to men killing their wives is highest for Aboriginals and lowest for Blacks, with the ratio for Whites falling in between. The possible sources of racial differences in this ratio include the proportion of couples (a) in common-law relationships, (b) who are co-residing as opposed to being separated, and (c) for whom there is a substantial age disparity between the partners. These factors are related to the spousal sex ratio of killing more generally. An exploration of interracial homicide patterns and racial variation in jealousy-motivated homicides was also undertaken. The findings reveal that controlling for the above factors substantially reduces the importance of race in predicting the gender of the homicide victim.

  1. Genetic architecture of sex determination in fish: Applications to sex ratio control in aquaculture

    Directory of Open Access Journals (Sweden)

    Paulino eMartínez

    2014-09-01

    Full Text Available 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

  2. Human semen quality and the secondary sex ratio

    Directory of Open Access Journals (Sweden)

    Jisuk Bae

    2017-01-01

    Full Text Available The aim of this study was to evaluate the association between semen quality and the secondary sex ratio (SSR, defined as the ratio of male to female live births. Our study cohort comprised 227 male partners who were enrolled prior to conception in Michigan and Texas between 2005 and 2009, and prospectively followed through delivery of a singleton birth. The male partners provided a baseline and a follow-up semen sample a month apart. Semen analysis was conducted to assess 27 parameters including five general characteristics, six sperm head measures, 14 morphology measures, and two sperm chromatin stability assay measures. Modified Poisson regression models with a robust error variance were used to estimate the relative risk (RR and 95% confidence interval (95% CI of a male birth for each semen parameter, after adjusting for potential confounders. Of the 27 semen parameters, only the percentage of bicephalic sperm was significantly associated with the SSR (2 nd vs 1 st quartile, RR, 0.65, 95% CI, 0.45-0.95, P = 0.03; 4 th vs 1 st quartile, RR, 0.61, 95% CI, 0.38-1.00, P < 0.05 before rounding to two decimal places, suggestive of a higher percentage of bicephalic sperm being associated with an excess of female births. Given the exploratory design of the present study, this preconception cohort study suggests no clear signal that human semen quality is associated with offspring sex determination.

  3. Sex, sex-ratios, and the dynamics of pelagic copepod populations

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2006-01-01

    I examine how the population biology of pelagic copepods depends on their mating biology using field data and a simple demographic model. Among calanoid copepods, two distinct patterns emerge. Firstly, copepods that lack seminal receptacle and require repeated mating to stay fertilized have near...... because they have on average a factor of 2 higher egg production rates than other pelagic copepods. Secondly, other copepods require only one mating to stay fertile, and populations of these species have strongly female-skewed adult sex-ratios in field populations. Resting eggs have not been described...... equal adult sex ratios in field populations. Winter population densities are orders of magnitude less than the critical population density required for population persistence, but populations survive winter seasons as resting eggs in the sediment. Population growth in these species is potentially high...

  4. Birds bias offspring sex ratio in response to livestock grazing.

    Science.gov (United States)

    Prior, Gina L; Evans, Darren M; Redpath, Stephen; Thirgood, Simon J; Monaghan, Pat

    2011-12-23

    Livestock grazing, which has a large influence on habitat structure, is associated with the widespread decline of various bird species across the world, yet there are few experimental studies that investigate how grazing pressure influences avian reproduction. We manipulated grazing pressure using a replicated field experiment, and found that the offspring sex ratio of a common upland passerine, the meadow pipit Anthus pratensis, varied significantly between grazing treatments. The proportion of sons was lowest in the ungrazed and intensively grazed treatments and highest in treatments grazed at low intensity (by sheep, or a mixture of sheep and cattle). This response was not related to maternal body condition. These results demonstrate the sensitivity of avian reproductive biology to variation in local conditions, and support growing evidence that too much grazing, or the complete removal of livestock from upland areas, is detrimental for common breeding birds.

  5. Age at marriage, sex-ratios, and ethnic heterogamy.

    Science.gov (United States)

    Stier, H; Shavit, Y

    1994-05-01

    "This paper focuses on the effects of age at marriage and the sex-ratio on patterns of ethnic homogamy among Israeli women. We hypothesize that later marriages are more likely than early marriages to be heterogamous as the 'marriage market' shifts from school to the work-place. By the same token, when facing severe marriage squeezes women will be forced to out-marry. Employing data from the 1983 census, we model mate selection of women from Afro-Asian and Euro-American origin in various birth-cohorts. The results do not fully support our hypotheses: we find that in and of itself, age at marriage does not enhance ethnic heterogamy." excerpt

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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…

  8. Sex hormones alter sex ratios in the Indian skipper frog, Euphlyctis cyanophlyctis: Determining sensitive stages for gonadal sex reversal.

    Science.gov (United States)

    Phuge, S K; Gramapurohit, N P

    2015-09-01

    In amphibians, although genetic factors are involved in sex determination, gonadal sex differentiation can be modified by exogenous steroid hormones suggesting a possible role of sex steroids in regulating the process. We studied the effect of testosterone propionate (TP) and estradiol-17β (E2) on gonadal differentiation and sex ratio at metamorphosis in the Indian skipper frog, Euphlyctis cyanophlyctis with undifferentiated type of gonadal differentiation. A series of experiments were carried out to determine the optimum dose and sensitive stages for gonadal sex reversal. Our results clearly indicate the importance of sex hormones in controlling gonadal differentiation of E. cyanophlyctis. Treatment of tadpoles with 10, 20, 40, and 80μg/L TP throughout larval period resulted in the development of 100% males at metamorphosis at all concentrations. Similarly, treatment of tadpoles with 40μg/L TP during ovarian and testicular differentiation resulted in the development of 90% males, 10% intersexes and 100% males respectively. Treatment of tadpoles with 10, 20, 40, and 80μg/L E2 throughout larval period likewise produced 100% females at all concentrations. Furthermore, exposure to 40μg/L E2 during ovarian and testicular differentiation produced 95% females, 5% intersexes and 91% females, 9% intersexes respectively. Both TP and E2 were also effective in advancing the stages of gonadal development. Present study shows the effectiveness of both T and E2 in inducing complete sex reversal in E. cyanophlyctis. Generally, exposure to E2 increased the larval period resulting in significantly larger females than control group while the larval period of control and TP treated groups was comparable. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Sex-ratio optimization with helpers at the nest

    NARCIS (Netherlands)

    Pen, I.R.; Weissing, F.J.

    2000-01-01

    In many cooperatively breeding animals, offspring produced earlier in life assist their parents in raising subsequent broods. Such helping behaviour is often confined to offspring of one sex. Sex-allocation theory predicts that parents overproduce offspring of the helping sex, but the expected

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

    Science.gov (United States)

    Jennions, Michael D; Fromhage, Lutz

    2017-09-19

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

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

    Science.gov (United States)

    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.

  12. Primary sex ratio adjustment by ant queens in response to local mate competition

    DEFF Research Database (Denmark)

    de Menten, Ludivine; Cremer, Sylvia; Heinze, Jürgen

    2005-01-01

    to adult sex ratios. With LMC, the primary sex ratio (proportion of haploid eggs laid by the queen) is expected to be female biased, which lowers the conflict between queens and workers over sex allocation. We compared the primary sex ratios laid by queens in monogynous and in polygynous experimental...... colonies of C. obscurior. The proportion of haploid eggs laid by queens was significantly lower in single-queen than in multiple-queen colonies. Furthermore, queens rapidly adjusted their primary sex ratios to changes in colony queen number. This is the first report of an adaptive adjustment of the primary...

  13. Offspring sex ratio in the sequentially polygamous Penduline Tit Remiz pendulinus

    NARCIS (Netherlands)

    van Dijk, Rene E.; Komdeur, Jan; van der Velde, Marco; Szentirmai, Istvan; Yang, Xutong; Ffrench-Constant, Richard; Szekely, Tamas; Friedl, T.

    2008-01-01

    Despite the growing literature on facultative sex-ratio adjustment in chromosomal sex-determining vertebrate taxa (birds, mammals), the consistency of results is often low between studies and species. Here, we investigate the primary and secondary offspring sex ratio of a small passerine bird, the

  14. An unstable social environment affects sex ratio in guinea pigs : an adaptive maternal effect?

    NARCIS (Netherlands)

    Kemme, Kristina; Kaiser, Sylvia; von Engelhardt, Nikolaus; Wewers, Dirk; Groothuis, Ton; Sachser, Norbert

    2009-01-01

    Evolutionary theory suggests that offspring sex should be adjusted to environmental conditions in order to maximize future reproductive success. In several animal taxa environmental factors indeed affect the secondary sex ratio. In humans, changes in the sex ratio at birth have been associated with

  15. Evidence of adaptive intergenerational sex ratio adjustment in contemporary human populations.

    Science.gov (United States)

    Song, Shige

    2014-03-01

    Using the abrupt decline in sex ratio at birth in China during and immediately after the 1959-1961 Great Leap Forward Famine in China as a natural experiment, this study conducts difference-in-differences analysis to test the hypothesis that changes in the sex ratio at birth of the maternal generation can produce adaptive changes in the sex ratio at birth of the offspring generation toward the opposite direction, which was derived from the developmental and evolutionary psychological literature on female reproductive strategy. The results show that, after controlling for sex-selective abortion, the decline in the sex ratio at birth in 1962-1964 caused a substantial increase in the sex ratio at birth among children whose mothers were born in 1963. Such finding suggests the presence of adaptive intergenerational sex ratio adjustment in humans. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. The validity of inferences of sex-selective infanticide, abortion and neglect from unusual reported sex ratios at birth.

    Science.gov (United States)

    James, W H

    1997-06-01

    In a 1995 study, Clark et al. report the births of 2429 boys and 2629 girls during 1956-91 in a group of Tonga speakers. The authors then extrapolated from Visaria's 1967 review of sex ratios from birth indicating the existence of a natural Black sex ratio at birth of 102 boys for every 100 girls to calculate that 250 boys had not been reported. These boys, however, may never have existed. One cannot infer present-day sex-related infanticide or induced abortion from present unanalyzed reported birth sex ratios in any society. That is the case because present sex ratios at birth are almost certainly dependent upon past sex prejudice, which is unquantifiable. Reporting bias and/or infanticide may be partly responsible for the deficit of boys in Clark et al.'s data, but other factors could also be responsible for the deficit. Sex ratios at birth and sex prejudice, and sex ratios at birth and polygyny are discussed.

  17. Maternal condition but not corticosterone is linked to offspring sex ratio in a passerine bird.

    Directory of Open Access Journals (Sweden)

    Lindsay J Henderson

    Full Text Available 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.

  18. Distortions of sex ratios at birth in the United States; evidence for prenatal gender selection.

    Science.gov (United States)

    Egan, James F X; Campbell, Winston A; Chapman, Audrey; Shamshirsaz, Alireza A; Gurram, Padmalatha; Benn, Peter A

    2011-06-01

    The normal male to female livebirth sex ratio ranges from 1.03 to 1.07. Higher ratios in China, India and Korea reflect prenatal sex selection. We reviewed sex ratios for US births to investigate potential prenatal sex selection. We reviewed all US livebirths from 1975 to 2002 using National Center for Health Statistics birth certificates in 4-year intervals. We compared the sex ratios of Blacks, Chinese, Filipinos, Asian Indians and Koreans relative to Whites. We also compared the sex ratios by birth order for first, second and third and more births (third+) from 1991 to 2002. The male to female sex ratio from 1975 to 2002 was 1.053 for Whites, 1.030 (p ratio increased from 1.071 to 1.086 for Chinese, 1.060 to 1.074 for Filipinos, 1.043 to 1.087 for Asian Indians and 1.069 to 1.088 for Koreans. The highest sex ratios were seen for third+ births to Asian Indians (1.126), Chinese (1.111) and Koreans (1.109). The male to female livebirth sex ratio in the United States exceeded expected biological variation for third+ births to Chinese, Asian Indians and Koreans strongly suggesting prenatal sex selection. Copyright © 2011 John Wiley & Sons, Ltd.

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

    OpenAIRE

    Varga, Sandra; Kytöviita, Minna-Maarit

    2011-01-01

    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 wa...

  20. Sex ratios of fledgling and recaptured subadult spotted owls in the southern Sierra Nevada

    Science.gov (United States)

    George N. Steger

    1995-01-01

    Estimates of instantaneous growth rates (A) of spotted owl (Strix occidentalis) populations have been based on demographic data that uniformly assumed an equal sex ratio among fledglings. In this study, sex ratios of subadults, banded as juveniles, and fledgling California spotted owls (S. o. occidentalis) were observed and compared to an assumed 1 : 1 ratio. The...

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

    NARCIS (Netherlands)

    Griskevicius, V.G.; Tybur, J.M.; Ackerman, J.M.; Delton, A.W.; Robertson, T.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,

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

    Science.gov (United States)

    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.

  3. Sex-specific early survival drives adult sex ratio bias in snowy plovers and impacts mating system and population growth.

    Science.gov (United States)

    Eberhart-Phillips, Luke J; Küpper, Clemens; Miller, Tom E X; Cruz-López, Medardo; Maher, Kathryn H; Dos Remedios, Natalie; Stoffel, Martin A; Hoffman, Joseph I; Krüger, Oliver; Székely, Tamás

    2017-07-03

    Adult sex ratio (ASR) is a central concept in population biology and a key factor in sexual selection, but why do most demographic models ignore sex biases? Vital rates often vary between the sexes and across life history, but their relative contributions to ASR variation remain poorly understood-an essential step to evaluate sex ratio theories in the wild and inform conservation. Here, we combine structured two-sex population models with individual-based mark-recapture data from an intensively monitored polygamous population of snowy plovers. We show that a strongly male-biased ASR (0.63) is primarily driven by sex-specific survival of juveniles rather than adults or dependent offspring. This finding provides empirical support for theories of unbiased sex allocation when sex differences in survival arise after the period of parental investment. Importantly, a conventional model ignoring sex biases significantly overestimated population viability. We suggest that sex-specific population models are essential to understand the population dynamics of sexual organisms: reproduction and population growth are most sensitive to perturbations in survival of the limiting sex. Overall, our study suggests that sex-biased early survival may contribute toward mating system evolution and population persistence, with implications for both sexual selection theory and biodiversity conservation.

  4. Sex-specific early survival drives adult sex ratio bias in snowy plovers and impacts mating system and population growth

    Science.gov (United States)

    Küpper, Clemens; Miller, Tom E. X.; Cruz-López, Medardo; Maher, Kathryn H.; dos Remedios, Natalie; Stoffel, Martin A.; Hoffman, Joseph I.; Krüger, Oliver; Székely, Tamás

    2017-01-01

    Adult sex ratio (ASR) is a central concept in population biology and a key factor in sexual selection, but why do most demographic models ignore sex biases? Vital rates often vary between the sexes and across life history, but their relative contributions to ASR variation remain poorly understood—an essential step to evaluate sex ratio theories in the wild and inform conservation. Here, we combine structured two-sex population models with individual-based mark–recapture data from an intensively monitored polygamous population of snowy plovers. We show that a strongly male-biased ASR (0.63) is primarily driven by sex-specific survival of juveniles rather than adults or dependent offspring. This finding provides empirical support for theories of unbiased sex allocation when sex differences in survival arise after the period of parental investment. Importantly, a conventional model ignoring sex biases significantly overestimated population viability. We suggest that sex-specific population models are essential to understand the population dynamics of sexual organisms: reproduction and population growth are most sensitive to perturbations in survival of the limiting sex. Overall, our study suggests that sex-biased early survival may contribute toward mating system evolution and population persistence, with implications for both sexual selection theory and biodiversity conservation. PMID:28634289

  5. High adult sex ratios and risky sexual behaviors: a systematic review.

    Directory of Open Access Journals (Sweden)

    Cedric H Bien

    Full Text Available 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.

  6. Sex Ratio and Sex Reversal in Two-year-old Class of Oyster, Crassostrea gigas (Bivalvia: Ostreidae)

    OpenAIRE

    Park, Jung Jun; Kim, Hyejin; Kang, Seung Wan; An, Cheul Min; Lee, Sung-Ho; Gye, Myung Chan; Lee, Jung Sick

    2012-01-01

    The sex ratio (F:M) in the same population of oyster, Crassostrea gigas at the commencement of the study (2007) was 1:1.0, but changed to 1:2.8 by the end of the study (2008). The sex reversal rate in two-year-old oysters was 40.2%. Specifically, female to male sex reversal rate was 66.1%, which is higher than the male to female sex reversal rate of 21.1%. The sex reversal pattern of C. gigas appears to go from male?female?male, and as such is determined to be rhythmical hermaphroditism.

  7. Sex Ratio and Sex Reversal in Two-year-old Class of Oyster, Crassostrea gigas (Bivalvia: Ostreidae).

    Science.gov (United States)

    Park, Jung Jun; Kim, Hyejin; Kang, Seung Wan; An, Cheul Min; Lee, Sung-Ho; Gye, Myung Chan; Lee, Jung Sick

    2012-12-01

    The sex ratio (F:M) in the same population of oyster, Crassostrea gigas at the commencement of the study (2007) was 1:1.0, but changed to 1:2.8 by the end of the study (2008). The sex reversal rate in two-year-old oysters was 40.2%. Specifically, female to male sex reversal rate was 66.1%, which is higher than the male to female sex reversal rate of 21.1%. The sex reversal pattern of C. gigas appears to go from male⇒female⇒male, and as such is determined to be rhythmical hermaphroditism.

  8. Sibling sex ratio of individuals diagnosed with autism spectrum disorder as children

    DEFF Research Database (Denmark)

    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...... the Danish live-birth sex ratio over the same period (0.514, p=0.001). The sibling sex ratio was not associated with the IQ in the autistic probands. INTERPRETATION: Our findings suggest a potential indirect confirmation of the androgen theory of autism....

  9. The evolution of sex ratio differences and inflorescence architectures in Begonia (Begoniaceae).

    Science.gov (United States)

    Twyford, Alex D; Ennos, Richard A; White, Chris D; Ali, Mobina Shaukat; Kidner, Catherine A

    2014-02-01

    A major benefit conferred by monoecy is the ability to alter floral sex ratio in response to selection. In monoecious species that produce flowers of a given sex at set positions on the inflorescence, floral sex ratio may be related to inflorescence architecture. We studied the loci underlying differences in inflorescence architecture between two monoecious Begonia species and related this to floral sex ratios. We performed trait comparisons and quantitative trait locus (QTL) mapping in a segregating backcross population between Central American Begonia plebeja and B. conchifolia. We focused on traits related to inflorescence architecture, sex ratios, and other reproductive traits. The inflorescence branching pattern of B. conchifolia was more asymmetric than B. plebeja, which in turn affects the floral sex ratio. Colocalizing QTLs of moderate effect influenced both the number of male flowers and the fate decisions of axillary meristems, demonstrating the close link between inflorescence architecture and sex ratio. Additional QTLs were found for stamen number (30% variance explained, VE) and pollen sterility (12.3% VE). One way in which Begonia species develop different floral sex ratios is through modifications of their inflorescence architecture. The potential pleiotropic action of QTL on inflorescence branching and floral sex ratios may have major implications for trait evolution and responses to selection. The presence of a single QTL of large effect on stamen number may allow rapid divergence for this key floral trait. We propose candidate loci for stamen number and inflorescence branching for future characterization.

  10. Spatial and temporal complexities of reproductive behavior and sex ratios: a case from parasitic insects.

    Directory of Open Access Journals (Sweden)

    Katharina Dittmar

    Full Text Available BACKGROUND: Sex ratios are important empirical data in predicting sex allocation strategy and selection in populations. Therefore, they should be sampled at crucial developmental steps before and after parental investment. In parasites with free-living (off-host developmental stages the timing and method of sampling is not trivial, because ecological niches are frequently poorly known. Consequently, information is scarce for sex ratios of these parasites between conception and sexual maturity. Often, only data from adult parasites are available, which usually were collected from the parasite's hosts. Generally, these ratios are assumed to represent operational sex ratios. METHODOLOGY/PRINCIPAL FINDINGS: We here report three years of empirical data on population sex differentials from a bat ectoparasite (Trichobius frequens with off-host developmental stages. At emergence these parasites exhibit a significant and seasonally stable female biased sex ratio. This bias is lost in the adult population on the roosting host, which shows sex ratios at equality. This is best explained by a behaviorally driven, sex-dependent mortality differential. Because consistently only subsets of females are available to mate, the operational sex ratio in the population is likely male biased. Host capture experiments throughout the day show a statistically significant, but temporary male excess in bat flies on foraging bats. This phenomenon is partly driven by the diurnal rhythms of female larviposition, and partly due to parasites remaining in the bat roost during foraging. Because most previous research in bat flies is based only on foraging bats, female contributions to physical sex ratios have been underestimated. CONCLUSION/SIGNIFICANCE: Our results highlight the importance of detailed natural history observations, and emphasize that ignoring the spatial and temporal heterogeneity of reproduction in any organism will lead to significant empirical sampling errors

  11. No evidence for selective follicle abortion underlying primary sex ratio adjustment in pigeons

    NARCIS (Netherlands)

    Goerlich, Vivian C.; Dijkstra, Cornelis; Groothuis, Antonius

    Primary sex ratio adjustment in birds has been extensively studied, yet the underlying physiological mechanisms are far from understood. Avian females are the heterogametic sex (ZW), and the future sex of the offspring is determined at chromosome segregation during meiosis I, shortly before the

  12. MATURATION, SEX RATIO AND FECUNDITY OF THE NILE PERCH ...

    African Journals Online (AJOL)

    ADMIN

    (1972) associates this phenomenon to sexual segregation where the females tend to congregate near the spawning grounds away from the open water. But, Hughes (1992) proposed protandrous sex reversal, with a few fish maturing as primary females. L. niloticus has the smallest egg sizes so far reported for African fish ...

  13. Sex Dimorphism of the Heart Diameters and Cardiothoracic Ratios ...

    African Journals Online (AJOL)

    Objective: To determine gender associated differences in the cardiothoracic ratio (CTR) and heart diameters in a normal Nigerian population. Subject and Method: The normal heart diameters and cardiothoracic ratios were measured from posteroanterior (PA) chest radiographs of healthy 510 male and 508 female ...

  14. Evidence for an altered sex ratio in clinic-referred adolescents with gender dysphoria.

    Science.gov (United States)

    Aitken, Madison; Steensma, Thomas D; Blanchard, Ray; VanderLaan, Doug P; Wood, Hayley; Fuentes, Amanda; Spegg, Cathy; Wasserman, Lori; Ames, Megan; Fitzsimmons, C Lindsay; Leef, Jonathan H; Lishak, Victoria; Reim, Elyse; Takagi, Anna; Vinik, Julia; Wreford, Julia; Cohen-Kettenis, Peggy T; de Vries, Annelou L C; Kreukels, Baudewijntje P C; Zucker, Kenneth J

    2015-03-01

    The number of adolescents referred to specialized gender identity clinics for gender dysphoria appears to be increasing and there also appears to be a corresponding shift in the sex ratio, from one favoring natal males to one favoring natal females. We conducted two quantitative studies to ascertain whether there has been a recent inversion of the sex ratio of adolescents referred for gender dysphoria. The sex ratio of adolescents from two specialized gender identity clinics was examined as a function of two cohort periods (2006-2013 vs. prior years). Study 1 was conducted on patients from a clinic in Toronto, and Study 2 was conducted on patients from a clinic in Amsterdam. Across both clinics, the total sample size was 748. In both clinics, there was a significant change in the sex ratio of referred adolescents between the two cohort periods: between 2006 and 2013, the sex ratio favored natal females, but in the prior years, the sex ratio favored natal males. In Study 1 from Toronto, there was no corresponding change in the sex ratio of 6,592 adolescents referred for other clinical problems. Sociological and sociocultural explanations are offered to account for this recent inversion in the sex ratio of adolescents with gender dysphoria. © 2015 International Society for Sexual Medicine.

  15. Sex ratios in the Arctic--do man-made chemicals matter?

    DEFF Research Database (Denmark)

    Bjerregaard, Peter; Chatwood, Susan; Denning, Bryany

    2013-01-01

    The objective was to analyze the variation of secondary sex ratios across the Arctic and to estimate the time trend. The rationale for this was claims in news media that, in the Arctic, sex ratios have become reduced due to exposure to anthropogenic contaminants in the environment....

  16. A statistical analysis of the effect of warfare on the human secondary sex ratio

    NARCIS (Netherlands)

    Graffelman, J.; Hoekstra, R.F.

    2000-01-01

    Many factors have been hypothesized to affect the human secondary sex ratio (the annual percentage of males among all live births), among them race, parental ages, and birth order. Some authors have even proposed warfare as a factor influencing live birth sex ratios. The hypothesis that during and

  17. Phenotypic sex ratios of Atriplex canescens shrubs in relation to cattle browsing

    Science.gov (United States)

    Andres F. Cibils; David M. Swift; Richard H. Hart

    2001-01-01

    Previous studies conducted at our research site on the shortgrass steppe in Colorado showed that phenotypic sex ratios of tetraploid fourwing saltbush (Atriplex canescens Pursh [Nutt]) shrubs were less female biased in grazed pastures than in adjacent exclosures. The potential effects of cattle browsing on shrub sex ratios were studied both in the field and in a...

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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

  20. Over-ripeness ovopathy: a challenging hypothesis for sex ratio modulation.

    NARCIS (Netherlands)

    Jongbloet, P.H.

    2004-01-01

    Current hypotheses do not explain the concerns about sex ratio modulation at conception, birth or during life, and particularly about sex ratio reversal, e.g. at very young or advanced maternal age, during 'anovulatory seasons', among those of low socio-economic status, or induced by specific

  1. Female-biased sex ratios in marine pelagic copepods: Comment on Gusmao et al. (2013)

    DEFF Research Database (Denmark)

    Hirst, Andrew G.; Bonnet, D; Conway, DVP

    2013-01-01

    Gusmao et al. (2013; Mar Ecol Prog Ser 482:279-298) review causes of sex ratio skew in pelagic copepods and in doing so repeatedly dispute the paper of Hirst et al. (2010) ‘Does predation control adult sex ratios and longevities in marine pelagic copepods?’ Here we respond to some important error...... in their citation of our paper and briefly highlight where future work is needed in order to attribute the causes of strong sex ratio skew seen in some copepod families......Gusmao et al. (2013; Mar Ecol Prog Ser 482:279-298) review causes of sex ratio skew in pelagic copepods and in doing so repeatedly dispute the paper of Hirst et al. (2010) ‘Does predation control adult sex ratios and longevities in marine pelagic copepods?’ Here we respond to some important errors...

  2. Falling sex ratios and emerging evidence of sex-selective abortion in Nepal: evidence from nationally representative survey data.

    Science.gov (United States)

    Frost, Melanie Dawn; Puri, Mahesh; Hinde, Peter Richard Andrew

    2013-05-14

    To quantify trends in changing sex ratios of births before and after the legalisation of abortion in Nepal. While sex-selective abortion is common in some Asian countries, it is not clear whether the legal status of abortion is associated with the prevalence of sex-selection when sex-selection is illegal. In this context, Nepal provides an interesting case study. Abortion was legalised in 2002 and prior to that, there was no evidence of sex-selective abortion. Changes in the sex ratio at birth since legalisation would suggest an association with legalisation, even though sex-selection is expressly prohibited. Analysis of data from four Demographic and Health Surveys, conducted in 1996, 2001, 2006 and 2011. Nepal. 31 842 women aged 15-49. Conditional sex ratios (CSRs) were calculated, specifically the CSR for second-born children where the first-born was female. This CSR is where the evidence of sex-selective abortion will be most visible. CSRs were looked at over time to assess the impact of legalisation as well as for population sub-groups in order to identify characteristics of women using sex-selection. From 2007 to 2010, the CSR for second-order births where the first-born was a girl was found to be 742 girls per 1000 boys (95% CI 599 to 913). Prior to legalisation of abortion (1998-2000), the same CSR was 1021 (906-1150). After legalisation, it dropped most among educated and richer women, especially in urban areas. Just 325 girls were born for every 1000 boys among the richest urban women. The fall in CSRs witnessed post-legalisation indicates that sex-selective abortion is becoming more common. This change is very likely driven by both supply and demand factors. Falling fertility has intensified the need to bear a son sooner, while legal abortion services have reduced the costs and risks associated with obtaining an abortion.

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

    Science.gov (United States)

    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

  4. Fertility transition and adverse child sex ratio in districts of India.

    Science.gov (United States)

    Mohanty, Sanjay K; Rajbhar, Mamta

    2014-11-01

    Demographic research in India over the last two decades has focused extensively on fertility change and gender bias at the micro-level, and less has been done at the district level. Using data from the Census of India 1991-2011 and other sources, this paper shows the broad pattern of fertility transition and trends in the child sex ratio in India, and examines the determinants of the child sex ratio at the district level. During 1991-2011, while the Total Fertility Rate (TFR) declined by 1.2 children per woman, the child sex ratio fell by 30 points in the districts of India. However, the reduction in fertility was slower in the high-fertility compared with the low-fertility districts. The gender differential in under-five mortality increased in many districts of India over the study period. The decline in the child sex ratio was higher in the transitional compared with the low-fertility districts. The transitional districts are at higher risk of a low child sex ratio due to an increased gender differential in mortality and increase in the practice of sex-selective abortions. The sex ratio at birth and gender differential in mortality explains one-third of the variation, while region alone explains a quarter of the variation in the child sex ratio in the districts of India.

  5. Does predation result in adult sex ratio skew in a sexually dimorphic insect genus?

    Science.gov (United States)

    Wehi, P M; Nakagawa, S; Trewick, S A; Morgan-Richards, M

    2011-11-01

    Theory proposes that sexually dimorphic, polygynous species are at particularly high risk of sex-biased predation, because conspicuous males are more often preyed upon compared to females. We tested the effects of predation on population sex ratio in a highly sexually dimorphic insect genus (Hemideina). In addition, introduction of a suite of novel mammalian predators to New Zealand during the last 800 years is likely to have modified selection pressures on native tree weta. We predicted that the balance between natural and sexual selection would be disrupted by the new predator species. We expected to see a sex ratio skew resulting from higher mortality in males with expensive secondary sexual weaponry; combat occurs outside refuge cavities between male tree weta. We took a meta-analytic approach using generalized linear mixed models to compare sex ratio variation in 58 populations for six of the seven species in Hemideina. We investigated adult sex ratio across these populations to determine how much variation in sex ratio can be attributed to sex-biased predation in populations with either low or high number of invasive mammalian predators. Surprisingly, we did not detect any significant deviation from 1 : 1 parity for adult sex ratio and found little difference between populations or species. We conclude that there is little evidence of sex-biased predation by either native or mammalian predators and observed sex ratio skew in individual populations of tree weta is probably an artefact of sampling error. We argue that sex-biased predation may be less prevalent in sexually dimorphic species than previously suspected and emphasize the usefulness of a meta-analytic approach to robustly analyse disparate and heterogeneous data. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

  6. (colouration) in progeny of Poecilia reticulate (guppy)

    African Journals Online (AJOL)

    There is high demand for ornamental fishes with improve colouration. Colouration is sex specific in Poecilia reticulate (Guppy) and the colour variation within the wild and exotic breeds is at variance. The effect of parental sex and breed on colouration of progeny in Poecilia reticulata (Guppy) was studied. Two breeds of P.

  7. A sex-ratio meiotic drive system in Drosophila simulans. I: an autosomal suppressor.

    Directory of Open Access Journals (Sweden)

    Yun Tao

    2007-11-01

    Full Text Available Sex ratio distortion (sex-ratio for short has been reported in numerous species such as Drosophila, where distortion can readily be detected in experimental crosses, but the molecular mechanisms remain elusive. Here we characterize an autosomal sex-ratio suppressor from D. simulans that we designate as not much yang (nmy, polytene chromosome position 87F3. Nmy suppresses an X-linked sex-ratio distorter, contains a pair of near-perfect inverted repeats of 345 bp, and evidently originated through retrotransposition from the distorter itself. The suppression is likely mediated by sequence homology between the suppressor and distorter. The strength of sex-ratio is greatly enhanced by lower temperature. This temperature sensitivity was used to assign the sex-ratio etiology to the maturation process of the Y-bearing sperm, a hypothesis corroborated by both light microscope observations and ultrastructural studies. It has long been suggested that an X-linked sex-ratio distorter can evolve by exploiting loopholes in the meiotic machinery for its own transmission advantage, which may be offset by other changes in the genome that control the selfish distorter. Data obtained in this study help to understand this evolutionary mechanism in molecular detail and provide insight regarding its evolutionary impact on genomic architecture and speciation.

  8. Sex ratios in juveniles and adults of Dichroplus maculipennis (Blanchard and Borellia bruneri (Rehn (Orthoptera: Acrididae

    Directory of Open Access Journals (Sweden)

    Yanina Mariottini

    2015-06-01

    Full Text Available Dichroplus maculipennis and Borellia bruneri are two of the 18 grasshopper species of actual or potential economic relevance as pests in Argentina. The objective of this study was to estimate the sex ratios for adults and older nymphs of D. maculipennis and B. bruneri in the field, and analyze possible temporal variations. The study was conducted during seven seasons (2005-06 to 2011-12 in representative plant communities of the southern Pampas region. A total of 4536 individuals of D. maculipennis, and 6038 individuals of B. bruneri were collected. The sex ratio registered in older nymphs for D. maculipennis and B. bruneri did not deviate from a 1:1 ratio (p > 0.05, suggesting that these species have such a primary sex ratio. However, a significant bias in sex composition in adults of both species was observed (p < 0.05. The sex ratio in adults of D. maculipennis was different in five of the 18 sampling dates carried out. In three sampling dates it was biased toward males, while in the other two it was biased toward females. Taking into account the sex ratio by sampling season, significant differences were recorded in two seasons. In 2007-08 the sex ratio was biased toward males (1 F:2.26 M, while in 2008-09 it was biased toward females (1.35 F:1 M. The sex ratio in adults of B. bruneri was always biased toward males (p < 0.05. We conclude that results obtained in this study indicate that various factors like differential survival, dispersion, predation, among others, could have modified the primary sex ratio in these species.

  9. Parental provisioning in relation to offspring sex and sex ratio in the great tit (Parus major)

    NARCIS (Netherlands)

    Michler, Stephanie P. M.; Bleeker, Maarten; van der Velde, Marco; Both, Christiaan; Komdeur, Jan; Tinbergen, Joost M.

    Sex-biased parental care is expected if the offspring sexes differ in their energetic needs or if they differentially affect their parents' reproductive success after independence. Furthermore, parents should adjust provisioning rate and prey size to the needs of individual nestlings and the entire

  10. Distorted Sex Ratios: A Window into RNAi-Mediated Silencing

    OpenAIRE

    Tao, Yun; Araripe, Luciana; Kingan, Sarah B; Ke, Yeyan; Xiao, Hailian; Hartl, Daniel L

    2007-01-01

    Author Summary Mendel's first law of genetics states that two alleles of a heterozygote are transmitted to the next generation at an equal ratio. The cornerstone of population genetics, this law states that the evolutionary fate of genetic variants is solely governed by their contribution to the good of their carriers. However, meiotic drive genes—which skew transmission in their own favor—can evolve under certain circumstances, even though they cause harm to the genome as a whole. Meiotic dr...

  11. Sex ratios, mating frequencies and relative abundance of sympatric millipedes in the genus Chersastus (Diplopoda: Pachybolidae

    Directory of Open Access Journals (Sweden)

    Mark Ian Cooper

    2014-12-01

    Full Text Available Three hypotheses exist for explaining climbing behavior in millipedes: 1 waterlogging, 2 detritus limiting, and 3 mate avoidance. Data of sex ratios, mating frequency and relative abundance are provided to suggest an alternative explanation for the pattern in sympatric forest millipedes. Sex ratio differences - from equality - were tested using a G-test comparing millipedes on and above ground. Mating frequencies were calculated based on the percentage of paired individuals. Relative abundance may correlate with male-biases in the sex ratios. All three factors suggest Chersastus inscriptus has a higher reproductive potential than C. anulatus. This is evidence for mating hotspots.

  12. The dynamics of sex ratio evolution: from the gene perspective to multilevel selection.

    Directory of Open Access Journals (Sweden)

    Krzysztof Argasinski

    Full Text Available The new dynamical game theoretic model of sex ratio evolution emphasizes the role of males as passive carriers of sex ratio genes. This shows inconsistency between population genetic models of sex ratio evolution and classical strategic models. In this work a novel technique of change of coordinates will be applied to the new model. This will reveal new aspects of the modelled phenomenon which cannot be shown or proven in the original formulation. The underlying goal is to describe the dynamics of selection of particular genes in the entire population, instead of in the same sex subpopulation, as in the previous paper and earlier population genetics approaches. This allows for analytical derivation of the unbiased strategic model from the model with rigorous non-simplified genetics. In effect, an alternative system of replicator equations is derived. It contains two subsystems: the first describes changes in gene frequencies (this is an alternative unbiased formalization of the Fisher-Dusing argument, whereas the second describes changes in the sex ratios in subpopulations of carriers of genes for each strategy. An intriguing analytical result of this work is that the fitness of a gene depends on the current sex ratio in the subpopulation of its carriers, not on the encoded individual strategy. Thus, the argument of the gene fitness function is not constant but is determined by the trajectory of the sex ratio among carriers of that gene. This aspect of the modelled phenomenon cannot be revealed by the static analysis. Dynamics of the sex ratio among gene carriers is driven by a dynamic "tug of war" between female carriers expressing the encoded strategic trait value and random partners of male carriers expressing the average population strategy (a primary sex ratio. This mechanism can be called "double-level selection". Therefore, gene interest perspective leads to multi-level selection.

  13. Live birth sex ratios and father's geographic origins in Jerusalem, 1964-1976.

    Science.gov (United States)

    Groeger, J; Opler, M; Kleinhaus, K; Perrin, M C; Calderon-Margalit, R; Manor, O; Paltiel, O; Conley, D; Harlap, S; Malaspina, D

    2017-05-06

    To examine whether ancestry influenced sex ratios of offspring in a birth cohort before parental antenatal sex selection influenced offspring sex. We measured the sex ratio as the percent of males according to countries of birth of paternal and maternal grandfathers in 91,459 live births from 1964 to 1976 in the Jerusalem Perinatal Study. Confidence limits (CI) were computed based on an expected sex ratio of 1.05, which is 51.4% male. Of all live births recorded, 51.4% were male. Relative to Jewish ancestry (51.4% males), significantly more males (1,761) were born to Muslim ancestry (54.5, 95% CI = 52.1-56.8, P = 0.01). Among the former, sex ratios were not significantly associated with paternal or maternal age, education, or offspring's birth order. Consistent with a preference for male offspring, the sex ratio decreased despite increasing numbers of births over the 13-year period. Sex ratios were not affected by maternal or paternal origins in North Africa or Europe. However, the offspring whose paternal grandfathers were born in Western Asia included fewer males than expected (50.7, 50.1-51.3, P = 0.02), whether the father was born abroad (50.7) or in Israel (50.8). This was observed for descendents of paternal grandfathers born in Lebanon (47.6), Turkey (49.9), Yemen & Aden (50.2), Iraq (50.5), Afghanistan (50.5), Syria (50.6), and Cyprus (50.7); but not for those from India (51.5) or Iran (51.9). The West Asian group showed the strongest decline in sex ratios with increasing paternal family size. A decreased sex ratio associated with ancestry in Western Asia is consistent with reduced ability to bear sons by a subset of Jewish men in the Jerusalem cohort. Lower sex ratios may be because of pregnancy stress, which may be higher in this subgroup. Alternatively, a degrading Y chromosome haplogroup or other genetic or epigenetic differences on male germ lines could affect birth ratios, such as differential exposure to an environmental agent, dietary

  14. Birth order, estrogens and sex-ratio adaptation in African wild dogs (Lycaon pictus).

    Science.gov (United States)

    Creel, S; Creel, N M; Monfort, S L

    1998-10-01

    Because the sex of mammals is chromosomally determined, populations generally produce a similar proportion of males and females. However, it has been recognized for more than century that individuals might increase their fitness by over-producing offspring of one sex, under certain conditions. Small biases in the secondary sex ratio are seen in many vertebrates. Here, we report that the sex ratio of primiparous African wild dogs (Lycaon pictus) is strongly biased in favor of sons (63%), while multiparous females produce an excess of daughters (64%). The direction of these biases is predicted by individual females' need for subordinate helpers. For humans, elevated estrogens have been hypothesized to bias the secondary sex ratio toward males. Consistent with this hypothesis, primiparous female wild dogs had basal estrogen levels double those of multiparous females.

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

    Directory of Open Access Journals (Sweden)

    Madhukar Shivajirao Dama

    Full Text Available 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.

  16. Different male vs. female breeding periodicity helps mitigate offspring sex ratio skews in sea turtles

    OpenAIRE

    Hays, Graeme C.; Mazaris, Antonios D.; Schofield, Gail

    2014-01-01

    The implications of climate change for global biodiversity may be profound with those species with little capacity for adaptation being thought to be particularly vulnerable to warming. A classic case of groups for concern are those animals exhibiting temperature-dependent sex-determination (TSD), such as sea turtles, where climate warming may produce single sex populations and hence extinction. We show that, globally, female biased hatchling sex ratios dominate sea turtle populations (exceed...

  17. Different male versus female breeding periodicity helps mitigate offspring sex ratio skews in sea turtles

    OpenAIRE

    Graeme Clive Hays; Gail eSchofield; Antonios D Mazaris

    2014-01-01

    The implications of climate change for global biodiversity may be profound with those species with little capacity for adaptation being thought to be particularly vulnerable to warming. A classic case of groups for concern are those animals exhibiting temperature-dependent sex-determination (TSD), such as sea turtles, where climate warming may produce single sex populations and hence extinction. We show that, globally, female biased hatchling sex ratios dominate sea turtle populations (exceed...

  18. Does predation control adult sex ratios and longevities in marine pelagic copepods?

    DEFF Research Database (Denmark)

    Hirst, A.G.; Bonnet, D.; Conway, D.V.P.

    2010-01-01

    We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late...... copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes...... in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona...

  19. Trends of human sex ratio at birth and twinning rate in Ibadan, south ...

    African Journals Online (AJOL)

    The human sex ratio at birth (SRB) and frequency of twinning are demographic parameters that vary among populations. A retrospective study was carried out to investigate the trend of SRB, as well as twinning rate in Ibadan, Nigeria. Data on sexes of singletons, twins, triplets and quadruplets from 1997 to 2008 collected ...

  20. Comparative AFLP reveals paternal sex ratio chromosome specific DNA sequences in the parasitoid wasp Trichogramma kaykai

    NARCIS (Netherlands)

    Vugt, van J.J.F.A.; Hulst, van der R.G.M.; Pruijssers, A.; Verbaarschot, P.G.H.; Stouthamer, R.; Jong, de H.

    2009-01-01

    The parasitoid wasp Trichogramma kaykai with a haplo-diploid sex determination has a B chromosome called the paternal sex ratio (PSR) chromosome that confers paternal genome loss during early embryogenesis, resulting in male offspring. So far, it is not well known whether the PSR chromosome has

  1. SEASONAL-VARIATION IN THE SEX-RATIO OF MARSH HARRIER CIRCUS-AERUGINOSUS BROODS

    NARCIS (Netherlands)

    ZIJLSTRA, M; DAAN, S; BRUINENBERGRINSMA, J

    1992-01-01

    1. Analysis of the sexes of 2260 nestlings in 735 marsh harrier broods revealed an overall excess [sex ratio (SR) = 54.8%] of males, and a significant increase in the proportion of males with progressive laying date (d = day of the year): In [SR/(1-SR)] = -1.286 + 0.013 d. 2. We argue that it is

  2. spatial-temporal variation in sex ratio and group size of ostriches

    African Journals Online (AJOL)

    Mgina

    ABSTRACT. A study was conducted on variation in sex ratio and group size of ostriches (Struthio camelus) in. Serengeti National Park and adjacent partially protected areas in northern Tanzania. Data were collected for two years (2005- 2006), along 388 km of roads. The two areas were compared with respect to ostrich sex ...

  3. Sex ratios under asymmetrical local mate competition : Theory and a test with parasitoid wasps

    NARCIS (Netherlands)

    Shuker, D.M.; Pen, I.R.; Duncan, A.B.; Reece, S.E.; West, S.A.

    Sex ratio theory allows unparalleled opportunities for testing how well animal behavior can be predicted by evolutionary theory. For example, Hamilton's theory of local mate competition (LMC) is well understood and can explain variation in sex allocation across numerous species. This allows more

  4. Occupational Perceptions of Males and Females as a Function of Sex Ratios, Salary, and Availability.

    Science.gov (United States)

    Subich, Linda Mezydlo; And Others

    1986-01-01

    Examined undergraduate students' willingness to explore, enter, and predict success in three occupations as a function of subject sex and information about occupational sex ratio, salary, and position availability. Results indicated males were more likely to report an interest in further exploration of and entry into the occupations, as well as to…

  5. Male-biased sex ratios in laboratory rearings of gypsy moth parasitoids

    Science.gov (United States)

    Roger W. Fuester; Kenneth S. Swan; Philip B. Taylor; Keith R. Hopper; Paul Ode

    2003-01-01

    Male-biased sex ratios in laboratory colonies of parasitic wasps used in biological control are harmful because they can prevent the establishment of introduced species or hinder commercial production of species used for augmentative control.

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

    Science.gov (United States)

    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

  7. Are sex ratio distorting endosymbionts responsible for mating system variation among dance flies (Diptera: Empidinae)?

    Science.gov (United States)

    Murray, Rosalind L; Herridge, Elizabeth J; Ness, Rob W; Bussière, Luc F

    2017-01-01

    Maternally inherited bacterial endosymbionts are common in many arthropod species. Some endosymbionts cause female-biased sex ratio distortion in their hosts that can result in profound changes to a host's mating behaviour and reproductive biology. Dance flies (Diptera: Empidinae) are well known for their unusual reproductive biology, including species with female-specific ornamentation and female-biased lek-like swarming behaviour. The cause of the repeated evolution of female ornaments in these flies remains unknown, but is probably associated with female-biased sex ratios in individual species. In this study we assessed whether dance flies harbour sex ratio distorting endosymbionts that might have driven these mating system evolutionary changes. We measured the incidence and prevalence of infection by three endosymbionts that are known to cause female-biased sex ratios in other insect hosts (Wolbachia, Rickettsia and Spiroplasma) across 20 species of dance flies. We found evidence of widespread infection by all three symbionts and variation in sex-specific prevalence across the taxa sampled. However, there was no relationship between infection prevalence and adult sex ratio measures and no evidence that female ornaments are associated with high prevalences of sex-biased symbiont infections. We conclude that the current distribution of endosymbiont infections is unlikely to explain the diversity in mating systems among dance fly species.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Explaining the Rapid Increase in Nigeria's Sex Ratio at Birth: Factors ...

    African Journals Online (AJOL)

    AJRH Managing Editor

    from the records of the Maternity Hospital for. 5,780 live births from 1976 to 1980, showed sex ratio of 1.2. ... sex ratio of 1.039 (1.07 for hospital deliveries, 1.037 for deliveries in maternity homes, and 1.02 for births in ..... earlier in adolescence than boys, who are more impulsive and take more risks than their sisters. Teenage ...

  10. Determinants of Declining Child Sex Ratio in India: An Empirical Investigation

    OpenAIRE

    Chakraborty, Lekha S.; Sinha, Darshy

    2006-01-01

    Using fixed effects model of pooled least squares for the last four decennial census data across fifteen major states in India; the paper examined the determinants of declining child sex ratio in India. The results suggest that the child sex ratio is inversely related to the spatial socio-economic characteristics, in particular, female literacy rate and female economic activity rate; with relatively higher elasticity coefficients for urban India. The spatial spillover effects associated with ...

  11. Explaining the Rapid Increase in Nigeria's Sex Ratio at Birth: Factors ...

    African Journals Online (AJOL)

    AJRH Managing Editor

    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 ...

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

    Directory of Open Access Journals (Sweden)

    Biliński Szczepan M

    2004-05-01

    Full Text Available Abstract 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.

  13. Revised evidence for facultative sex ratio adjustment in birds: a correction.

    Science.gov (United States)

    Cassey, Phillip; Ewen, John G; Møller, Anders P

    2006-12-22

    We provide a revision to the calculation of effect sizes and heterogeneity statistics in our original article, 'Facultative primary sex ratio variation: a lack of evidence in birds' (Ewen et al. 2004). Our revision shows that significant heterogeneity in sex ratio study effect sizes does indeed exist and that for a series of key traits the average effect sizes (while still weak) are in fact significantly different from zero.

  14. Sex ratio and time to pregnancy: analysis of four large European population surveys

    DEFF Research Database (Denmark)

    Joffe, Mike; Bennett, James; Best, Nicky

    2007-01-01

    To test whether the secondary sex ratio (proportion of male births) is associated with time to pregnancy, a marker of fertility. Design Analysis of four large population surveys. Setting Denmark and the United Kingdom. Participants 49 506 pregnancies.......To test whether the secondary sex ratio (proportion of male births) is associated with time to pregnancy, a marker of fertility. Design Analysis of four large population surveys. Setting Denmark and the United Kingdom. Participants 49 506 pregnancies....

  15. Secondary sex ratio in regions severely exposed to methylmercury "Minamata disease".

    Science.gov (United States)

    Yorifuji, Takashi; Kashima, Saori

    2016-05-01

    Secondary sex ratio (i.e., male proportion at birth) is considered to function as a sentinel health indicator. Thus, examining this ratio spatially and temporally in regions with severe environmental exposure to compounds such as methylmercury may provide insight into the evolution of exposure. We evaluated spatial and temporal distributions of the secondary sex ratio in Minamata, Japan, and neighboring areas, where severe methylmercury poisoning occurred in the 1950s and 1960s. We selected four areas exposed to methylmercury: Minamata, Ashikita, Goshonoura, and Izumi. After obtaining the number of live births, we conducted descriptive analyses by study area. We observed a reduction in male births in the exposed areas. In particular, a decline in the sex ratio of the Minamata area, where the first patient was officially identified in 1956, was seen around 1955. The ratio during 1955-1959 around Minamata was 0.496 [95% confidence interval (CI) 0.481-0.511]; the 95% CI did not include the value of 0.515 (the secondary sex ratio of the entire Japanese population during the study period). Declines in this ratio were also observed in other exposed areas around 1960, when acetaldehyde production (the origin of methylmercury) reached its peak. These analyses demonstrate that temporal and spatial distributions of the secondary sex ratio reflect the evolution of methylmercury exposure corresponding with the known history of Minamata disease.

  16. EFFECT OF GENETIC AND ENVIRONMENTAL FACTORS ON SEX RATIO IN CROSSBRED PIGS

    Directory of Open Access Journals (Sweden)

    S. Naskar

    2012-12-01

    Full Text Available The study was initiated with an idea to investigate few genetic and environmental factors that affect sex ratio of Khasi local and their different crossbreds with Hampshire pigs. Individual data were collected of pure Khasi local and its crossbred with 50, 75 and 87.5 % Hampshire inheritance in different seasons like rainy (July to October, summer (March-June and winter (Nov- Feb. The sex ratio for Khasi local crossbred with 50, 75 and 87.5 % Hampshire inheritance was 1.21 ± 0.16, 1.32 ± 0.16, 1.48 ± 0.16 an 1.32 ± 0.16 respectively with an overall mean sex ratio 1.38 ± 0.16, whereas, the sex ratio for spring, rainy and winter season was 1.31 ± 0.17, 1.29 ± 0.16 and 1.32 ± 0.15, respectively. Similarly, the sex ratio for larger litters and smaller litters was 1.40 ± 0.13 and 1.45 ± 0.13 respectively. This study concludes that crossbreds at different levels of inheritance, season and litter size had no effect on sex ratio.

  17. Testing sex ratio theory with the malaria parasite Plasmodium mexicanum in natural and experimental infections.

    Science.gov (United States)

    Neal, Allison T; Schall, Jos J

    2014-04-01

    The malaria parasite (Plasmodium) life history accords well with the assumptions of local mate competition (LMC) of sex ratio theory. Within a single meal of the blood-feeding vector, sexually dimorphic gametocyte cells produce gametes (females produce one, males several) that mate and undergo sexual recombination. The theory posits several factors drive the Plasmodium sex ratio: male fecundity (gametes/male gametocyte), number and relative abundance of parasite clones, and gametocyte density. We measured these traits for the lizard malaria parasite, Plasmodium mexicanum, with a large sample of natural infections and infections from experiments that manipulated clonal diversity. Sex ratio in single-clone infections was slightly female-biased, but matched predictions of theory for this low-fecundity species. Sex ratio was less female-biased in clonally diverse infections as predicted by LMC for the experimental, but not natural infections. Gametocyte density was not positively related to sex ratio. These results are explained by the P. mexicanum life history of naturally low clonal diversity and high gametocyte production. This is the first study of a natural malaria system that examines all traits relevant to LMC in individual vertebrate hosts and suggests a striking example of sex ratio theory having significance for human public health. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  18. Geographical variations in sex ratio trends over time in multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Maria Trojano

    Full Text Available BACKGROUND: A female/male (F/M ratio increase over time in multiple sclerosis (MS patients was demonstrated in many countries around the world. So far, a direct comparison of sex ratio time-trends among MS populations from different geographical areas was not carried out. OBJECTIVE: In this paper we assessed and compared sex ratio trends, over a 60-year span, in MS populations belonging to different latitudinal areas. METHODS: Data of a cohort of 15,996 (F = 11,290; M = 4,706 definite MS with birth years ranging from 1930 to 1989 were extracted from the international MSBase registry and the New Zealand MS database. Gender ratios were calculated by six decades based on year of birth and were adjusted for the F/M born-alive ratio derived from the respective national registries of births. RESULTS: Adjusted sex ratios showed a significant increase from the first to the last decade in the whole MS sample (from 2.35 to 2.73; p = 0.03 and in the subgroups belonging to the areas between 83° N and 45° N (from 1.93 to 4.55; p<0.0001 and between 45° N to 35° N (from 1.46 to 2.30; p<0.05 latitude, while a sex ratio stability over time was found in the subgroup from areas between 12° S and 55° S latitude. The sex ratio increase mainly affected relapsing-remitting (RR MS. CONCLUSIONS: Our results confirm a general sex ratio increase over time in RRMS and also demonstrate a latitudinal gradient of this increase. These findings add useful information for planning case-control studies aimed to explore sex-related factors responsible for MS development.

  19. No evidence for selective follicle abortion underlying primary sex ratio adjustment in pigeons.

    Science.gov (United States)

    Goerlich, Vivian C; Dijkstra, Cor; Groothuis, Ton G G

    2010-03-01

    Primary sex ratio adjustment in birds has been extensively studied, yet the underlying physiological mechanisms are far from understood. Avian females are the heterogametic sex (ZW), and the future sex of the offspring is determined at chromosome segregation during meiosis I, shortly before the oocyte is ovulated. Assuming that the mother can detect the sex of the developing oocyte before ovulation, it has been suggested that a follicle of the un-preferred sex could selectively be induced to become atretic and regress instead of being ovulated (selective follicle abortion). This potential mechanism has been proposed to underlie biased primary sex ratios in birds, including the homing pigeon (Columba livia domestica), which produces a modal clutch size of two eggs. However, without replacement by an additional, already mature follicle, abortion of a preovulatory follicle would most likely result in either reduced clutch sizes or laying gaps, since a not-yet-recruited follicle still needed to undergo the whole maturation phase. In the current study we killed female pigeons, which were adjusting embryo sex of first eggs according to change in body mass. We examined ovaries for signs of follicle abortion but did not find any supporting evidence. All females produced one or two mature follicles but only two out of the 56 experimental birds produced an additional third mature follicle. Therefore, our results do not corroborate the hypothesis that pigeon mothers manipulate primary offspring sex by selectively aborting follicles of the un-preferred sex.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  2. EFFECT OF THE SEX RATIO ON THE EGG FERTILITY OF MUSCOVY DUCK (CAIRINA MOSHCATA

    Directory of Open Access Journals (Sweden)

    Matina NICKOLOVA

    2005-04-01

    Full Text Available Study was carried out for establishing the optimal sex ratio in Muscovy duck breeding. Four variants of the ratio of the male to the female individuals were tested: 1:5(I, 1:6(II, 1:7(III and 1:8(IV. In the frames of each sex ratio (variant, two subgroups (sub-variants were formed with the aim of establishing the effect of the hierarchy relations among the drakes on egg fertility: with one male in a group (A and with more than one male in a group (B. The highest egg fertility – 97.09 % was achieved at 1:5 sex ratio (with more than one drake in a group and the lowest – 93.41 % at 1:8 sex ratio (with a single male in a group. Signifi cant decrease in egg fertility was registered when increasing the sex ratio to 1:8, that effect being displayed more weakly at more than one male in the group. When increasing the ratio, the presence of more than one drake in the family group exerted a positive infl uence on egg fertility, due to the preference of the males to certain females and the distribution of the rest of the females among the drakes placed in the hierarchy below the “alpha”, depending on their grade in the hierarchy order. The most appropriate sex ratio for Muscovy duck species was 1:5, and, when there was shortage of the male reproduction material, 1:6 ratio was also acceptable, especially if more than one drakes were placed in the family group (effect of supporting the alpha.

  3. Variation in offspring sex ratio of a long-lived sexually dimorphic raptor, the eastern imperial eagle (Aquila heliaca)

    Science.gov (United States)

    Todd E. Katzner; Daniel S. Jackson; Jamie Ivy; Evgeny A. Bragin; Andrew. Dewoody

    2014-01-01

    Sex ratio theory attempts to explain observed variation in offspring sex ratio at both the population and the brood levels. In the context of low-fecundity organisms producing high-investment offspring, the drivers of adaptive variation in sex ratio are incompletely understood. For raptors that display reverse sexual dimorphism (RSD), preferential allocation of...

  4. Sibling Sex Ratio and Birth Order in Early-Onset Gender Dysphoric Adolescents

    NARCIS (Netherlands)

    Schagen, S.E.E.; Delemarre-van de Waal, H.A.; Blanchard, R.; Cohen-Kettenis, P.T.

    2012-01-01

    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,

  5. Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

    DEFF Research Database (Denmark)

    Timmermann, Clara Amalie Gade; Choi, Anna L.; Petersen, Maria Skaalum

    2017-01-01

    This study was undertaken to assess the potential impact of maternal exposures to polychlorinated biphenyl (PCB), dichlorodiphenyl dichloroethylene (DDE) and methylmercury on the secondary sex ratios (the ratio of male to female live births) over a span of 23 years. The study includes prospective......% CI = 2-17%), respectively, of giving birth to a boy. In conclusion, maternal exposure to ΣPCB, DDE and methylmercury was associated with a slightly increased secondary sex ratio. The impact of paternal exposures could not be taken into account and deserves attention....

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

    Science.gov (United States)

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

    2012-06-01

    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. 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 >1 sex partner in the past month. 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 (NHW) women, low sex ratios were associated with having >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; NHW: ARR = 1.39, 95% CI: 1.05, 1.85; Hispanic: ARR = 3.99, 95% CI = 1.55, 10.26) and having >1 partner among NHW men (ARR = 1.92, 95% CI = 1.40, 2.64). 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.

  7. Digit Ratio (2D:4D): A Biomarker for Prenatal Sex Steroids and Adult Sex Steroids in Challenge Situations

    OpenAIRE

    Manning, John; Kilduff, Liam; Cook, Christian; Crewther, Blair; Fink, Bernhard

    2014-01-01

    Digit ratio (2D:4D), which denotes the relative length of the 2nd and 4th digits, is considered to be a biomarker of the balance between foetal testosterone and oestrogen in a narrow window of early ontogeny. Evidence from this assertion is derived from direct and indirect measures of prenatal hormonal exposure (in experimental animals, via amniotic fluid samples and in the study of sex-typical traits) in relation to 2D:4D. In contrast, the relationships between 2D:4D and levels of sex steroi...

  8. Adult sex ratios of loggerhead sea turtles (Caretta caretta in two Mediterranean foraging grounds

    Directory of Open Access Journals (Sweden)

    Paolo Casale

    2014-06-01

    Full Text Available Sea turtles show temperature-dependent sex determination (TSD and information on sex ratios at different life stages is necessary both for population dynamics models for conservation and to shed light on the possible adaptive value of TSD. Adults represent the less abundant class of sea turtle populations and adult sex ratios at foraging grounds are very difficult to obtain. We first analysed biometric data of 460 juvenile and adult loggerhead sea turtles ranging from 60 to 97.5 cm curved carapace length (CCL, in which a clear bimodal distribution of tail length (the main secondary sexual character of adult males was observed in the size class >75 cm CCL. We then sexed 142 adult turtles in this size class collected from the Tunisian shelf and from the southeastern Tyrrhenian Sea, observing a proportion of females of 51.5% (95% CI: 41.2-61.8%; n=97 and 40.0% (95% CI: 25.7-55.7%; n=45 respectively. Our results complement previous studies and support their findings of similar and more balanced sex ratios in adult and juvenile loggerhead turtles in the Mediterranean, in contrast with highly female-biased sex ratios of hatchlings.

  9. Different male versus female breeding periodicity helps mitigate offspring sex ratio skews in sea turtles

    Directory of Open Access Journals (Sweden)

    Graeme Clive Hays

    2014-09-01

    Full Text Available The implications of climate change for global biodiversity may be profound with those species with little capacity for adaptation being thought to be particularly vulnerable to warming. A classic case of groups for concern are those animals exhibiting temperature-dependent sex-determination (TSD, such as sea turtles, where climate warming may produce single sex populations and hence extinction. We show that, globally, female biased hatchling sex ratios dominate sea turtle populations (exceeding 3:1 in >50% records, which, at-a-glance, reiterates concerns for extinction. However, we also demonstrate that more frequent breeding by males, empirically shown by satellite tracking 23 individuals and supported by a generalized bio-energetic life history model, generates more balanced operational sex ratios (OSRs. Hence, concerns of increasingly skewed hatchling sex ratios and reduced population viability are less acute than previously thought for sea turtles. In fact, in some scenarios skewed hatchling sex ratios in groups with TSD may be adaptive to ensure optimum OSRs.

  10. Different sex ratios of children born to Indian and Pakistani immigrants in Norway

    Directory of Open Access Journals (Sweden)

    Brekke Torkel

    2010-08-01

    Full Text Available Abstract Background A low female-to-male ratio has been observed in different Asian countries, but this phenomenon has not been well studied among immigrants living in Western societies. In this study, we investigated whether a low female-to-male ratio exists among Indian and Pakistani immigrants living in Norway. In particular, we investigated whether the determination of sex via ultrasound examination, a common obstetric procedure that has been used in Norway since the early 1980 s, has influenced the female-to-male ratio among children born to parents of Indian or Pakistani origin. Methods We performed a retrospective cohort study of live births in mothers of Indian (n = 1597 and Pakistani (n = 5617 origin. Data were obtained from "Statistics Norway" and the female-to-male (F/M sex ratio was evaluated among 21,325 children born, in increasing birth order, during three stratified periods (i.e., 1969-1986, 1987-1996, and 1997-2005. Results A significant low female-to-male sex ratio was observed among children in the third and fourth birth order (sex ratio 65; 95% CI 51-80 from mothers of Indian origin who gave birth after 1987. Sex ratios did not deviate from the expected natural variation in the Indian cohort from 1969 to 1986, and remained stable in the Pakistani cohort during the entire study period. However, the female-to-male sex ratio seemed less skewed in recent years (i.e., 1997-2005. Conclusion Significant differences were observed in the sex ratio of children born to mothers of Indian origin compared with children born to mothers of Pakistani origin. A skewed number of female births among higher birth orders (i.e., third or later may partly reflect an increase in sex-selective abortion among mothers of Indian origin, although the numbers are too small to draw firm conclusions. Further research is needed to explain the observed differences in the female-to-male ratio among members of these ethnic groups who reside in Norway.

  11. Facultative primary sex ratio variation: a lack of evidence in birds?

    Science.gov (United States)

    Ewen, John G; Cassey, Phillip; Møller, Anders P

    2004-06-22

    The facultative control of primary sex ratio by breeding birds has become a major focus in evolutionary biology in recent years. A combination of well-developed theoretical literature and rapid publication of empirical results has created considerable confusion, with controversial claims for both extreme control of primary sex ratio versus no control around inherent random variability. We present a robust and quantitative summary of published empirical literature to assess clearly the body of evidence for female birds to control sex assignment in their offspring. Our meta-analytical approach reveals that published studies do not exhibit any variability beyond that which could be expected owing to sampling error. Therefore, we conclude that facultative control of offspring sex is not a characteristic biological phenomenon in breeding birds.

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

    Science.gov (United States)

    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

  13. Elevated mortality among birds in Chernobyl as judged from skewed age and sex ratios.

    Directory of Open Access Journals (Sweden)

    Anders Pape Møller

    Full Text Available 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

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

    Science.gov (United States)

    Scherb, Hagen; Kusmierz, Ralf; Voigt, Kristina

    2013-08-15

    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. 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. 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 Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90. 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.

  15. Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies.

    Science.gov (United States)

    Schacht, Ryan; Kramer, Karen L; Székely, Tamás; Kappeler, Peter M

    2017-09-19

    It is increasingly recognized that the relative proportion of potential mates to competitors in a population impacts a range of sex-specific behaviours and in particular mating and reproduction. However, while the adult sex ratio (ASR) has long been recognized as an important link between demography and behaviour, this relationship remains understudied. Here, we introduce the first inter-disciplinary collection of research on the causes and consequences of variation in the ASR in human and animal societies. This important topic is relevant to a wide audience of both social and biological scientists due to the central role that the relative number of males to females in a population plays for the evolution of, and contemporary variation in, sex roles across groups, species and higher taxa. The articles in this theme issue cover research on ASR across a variety of taxa and topics. They offer critical re-evaluations of theoretical foundations within both evolutionary and non-evolutionary fields, and propose innovative methodological approaches, present new empirical examples of behavioural consequences of ASR variation and reveal that the ASR plays a major role in determining population viability, especially in small populations and species with labile sex determination. This introductory paper puts the contributions of the theme issue into a broader context, identifies general trends across the literature and formulates directions for future research.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

  16. The Facial Width-to-Height Ratio Predicts Sex Drive, Sociosexuality, and Intended Infidelity.

    Science.gov (United States)

    Arnocky, Steven; Carré, Justin M; Bird, Brian M; Moreau, Benjamin J P; Vaillancourt, Tracy; Ortiz, Triana; Marley, Nicole

    2017-09-19

    Previous research has linked the facial width-to-height ratio (FWHR) to a host of psychological and behavioral characteristics, primarily in men. In two studies, we examined novel links between FWHR and sex drive. In Study 1, a sample of 145 undergraduate students revealed that FWHR positively predicted sex drive. There were no significant FWHR × sex interactions, suggesting that FWHR is linked to sexuality among both men and women. Study 2 replicated and extended these findings in a sample of 314 students collected from a different Canadian city, which again demonstrated links between the FWHR and sex drive (also in both men and women), as well as sociosexuality and intended infidelity (men only). Internal meta-analytic results confirm the link between FWHR and sex drive among both men and women. These results suggest that FWHR may be an important morphological index of human sexuality.

  17. Differential timing and latitudinal variation in sex ratio of Aquatic Warblers during the autumn migration

    Science.gov (United States)

    Wojczulanis-Jakubas, Katarzyna; Chrostek, Małgorzata E.; Jiguet, Frédéric; Martínez, Carlos Zumalacárregui; Miguélez, David; Neto, Júlio M.

    2017-12-01

    Differential migration has been extensively reported in spring, but less so in autumn, particularly in relation to sex in monomorphic bird species. Here, we analysed the autumn passage of a monomorphic, globally threatened passerine, the Aquatic Warbler Acrocephalus paludicola throughout Western Europe, with regard to age and sex. We showed that, overall, adults migrated earlier than first-year birds, and males migrated earlier than females during the autumn migration. This may be caused by an overall social dominance of adults over immatures, and differentiated migration strategy of males and females. In addition, we found male-skewed sex proportions, with a tendency to an equalised ratio in more southern stopover sites. This may indicate a male bias in the global population or different migration strategies of the sexes. Differential migration may cause the age and sex classes to be exposed differently to various threats affecting demographic structure of the species.

  18. Why is mutual mate choice not the norm? Operational sex ratios, sex roles and the evolution of sexually dimorphic and monomorphic signalling

    National Research Council Canada - National Science Library

    H. Kokko; R. A. Johnstone

    2002-01-01

    Biases in the operational sex ratio (OSR) are seen as the fundamental reason behind differential competition for mates in the two sexes, and as a strong determinant behind differences in choosiness...

  19. Digit Ratio (2D:4D): A Biomarker for Prenatal Sex Steroids and Adult Sex Steroids in Challenge Situations

    Science.gov (United States)

    Manning, John; Kilduff, Liam; Cook, Christian; Crewther, Blair; Fink, Bernhard

    2013-01-01

    Digit ratio (2D:4D) denotes the relative length of the second and fourth digits. This ratio is considered to be a biomarker of the balance between fetal testosterone (T) and estrogen (E) in a narrow window of early ontogeny. Evidence for this assertion is derived from direct and indirect measures of prenatal hormonal exposure (in experimental animals, via amniotic fluid samples and in the study of sex-typical traits) in relation to 2D:4D. In contrast, the relationships between 2D:4D and levels of sex steroids in adults are less clear, as many correlational studies of 2D:4D and adult sex steroids have concluded that this association is statistically non-significant. Here, we suggest that in order to understand the link between 2D:4D and sex hormones, one must consider both fetal organizing and adult activating effects of T and E. In particular, we hypothesize that 2D:4D correlates with organizing effects on the endocrine system that moderate activating effects in adulthood. We argue that this is particularly evident in “challenging” conditions such as aggressive and sexual encounters, in which individuals show increased levels of T. We discuss this refinement of the 2D:4D paradigm in relation to the links between 2D:4D and sports performance, and aggression. PMID:24523714

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

    Science.gov (United States)

    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.

  1. The Relationship of Body Length and Ratio Pappilla with Sex in Gobi Fish (Sicyopterus macrostetholepis

    Directory of Open Access Journals (Sweden)

    Rona Taula Sari

    2017-07-01

    Full Text Available Research about the relationship of body length and ratio papilla with sex in goby fish (S. macrostetholepis Blkr. has been done at Animal Structure and Developmental Laboratory, Biologi Department, Faculty of Matematics and Natural Sciences, Andalas University, Padang, which purposed to analyse the relationship of body length and ratio papilla with sex of goby fish (S. macrostetholepis Blkr.. The samples were taken in wild stream area at Batangkuranji river, Padang City. This research used descriptive method and data were analyzed by qualitatively and quantitatively. The results of investigation showed that in several goby fishes (S. macrostetholepis Blkr. with different sex had the same of body length and the same of ratio papilla. So, there was not relationship between of body length and ratio papilla with sex.  Goby fishes (S. macrostetholepis Blkr. it belongs to the hermaphrodite protogini, which the androgynous young females, while in adulthood, it would change sex to male. The results of this study are expected to add to the treasures of knowledge and information about reproductive gobies (S. macrostetholepis Blkr. in the preservation and development of fish farming.   

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

    Science.gov (United States)

    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.

  3. Sex ratio bias and extinction risk in an isolated population of Tuatara (Sphenodon punctatus.

    Directory of Open Access Journals (Sweden)

    Kristine L Grayson

    Full Text Available Understanding the mechanisms underlying population declines is critical for preventing the extinction of endangered populations. Positive feedbacks can hasten the process of collapse and create an 'extinction vortex,' particularly in small, isolated populations. We provide a case study of a male-biased sex ratio creating the conditions for extinction in a natural population of tuatara (Sphenodon punctatus on North Brother Island in the Cook Strait of New Zealand. We combine data from long term mark-recapture surveys, updated model estimates of hatchling sex ratio, and population viability modeling to measure the impacts of sex ratio skew. Results from the mark-recapture surveys show an increasing decline in the percentage of females in the adult tuatara population. Our monitoring reveals compounding impacts on female fitness through reductions in female body condition, fecundity, and survival as the male-bias in the population has increased. Additionally, we find that current nest temperatures are likely to result in more male than female hatchlings, owing to the pattern of temperature-dependent sex determination in tuatara where males hatch at warmer temperatures. Anthropogenic climate change worsens the situation for this isolated population, as projected temperature increases for New Zealand are expected to further skew the hatchling sex ratio towards males. Population viability models predict that without management intervention or an evolutionary response, the population will ultimately become entirely comprised of males and functionally extinct. Our study demonstrates that sex ratio bias can be an underappreciated threat to population viability, particularly in populations of long-lived organisms that appear numerically stable.

  4. Digit Ratio (2D:4D: A biomarker for prenatal sex steroids and adult sex steroids in challenge situations

    Directory of Open Access Journals (Sweden)

    John eManning

    2014-01-01

    Full Text Available Digit ratio (2D:4D, which denotes the relative length of the 2nd and 4th digits, is considered to be a biomarker of the balance between foetal testosterone and oestrogen in a narrow window of early ontogeny. Evidence from this assertion is derived from direct and indirect measures of prenatal hormonal exposure (in experimental animals, via amniotic fluid samples and in the study of sex-typical traits in relation to 2D:4D. In contrast, the relationships between 2D:4D and levels of sex steroids in adults are less clear, as many correlational studies of 2D:4D and adult sex steroids have concluded that there is little in the way of associations. Here we suggest that in order to understand the link between 2D:4D and sex hormones one must consider both foetal organising and adult activating effects of testosterone and oestrogen. In particular, we hypothesise that 2D:4D correlates with early organising effects on the endocrine system that moderate activating effects in adulthood. We argue that this can be especially observed through an elevated propensity in adults to produce testosterone in challenging conditions such as aggressive and sexual encounters. We discuss this refinement of the 2D:4D paradigm in relation to the links between 2D:4D and sports performance, and aggression.

  5. Sex Ratio at Birth in Vietnam: Results From Data in CHILILAB HDSS, 2004 to 2013.

    Science.gov (United States)

    Le, Vui Thi; Duong, Duc Minh; Nguyen, Anh Duy; Nguyen, Chuong Canh; Bui, Ha Thi Thu; Pham, Cuong Viet; Le, Thi Minh; Tran, Bich Huu

    2017-07-01

    This study aimed to explore the association of demographic and socioeconomic characteristics and imbalanced sex ratio at birth (SRB) in Chi Linh district, Hai Duong. The data were collected from a longitudinal study using a community-based periodic, referred as Chi Linh Health and Demographic Surveillance System (CHILILAB HDSS) during 2004 to 2013. A total of 7568 children were analyzed. Results showed that SRB in Chi Linh dramatically increased to the imbalanced sex ratio (114.6 boys to 100 girls) by 2013. SRB was associated with birth order and sex of preceding siblings. SRB was extremely high among families without any sons (136/100). SRB was highest among families having third or more children (175/100). Imbalanced SRB was more likely to occur among women working in small business/homemakers and others, women who attained high education level, and women in wealthy households. We suggested further efforts to tackle imbalanced SRB in periurban areas in Vietnam.

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

    Science.gov (United States)

    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…

  7. [Paternal exposure to occupational electromagnetic radiation and sex ratio of the offspring: a meta-analysis].

    Science.gov (United States)

    Tong, Shu-Hui; Liu, Yi-Ting; Liu, Yang

    2013-02-01

    To investigate the association between paternal exposure to occupational electromagnetic radiation and the sex ratio of the offspring. We searched various databases, including PubMed, Embase, Cochrane Library, OVID, Bioscience Information Service (BIOSIS), China National Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals and Wanfang Database, for the literature relevant to the association of paternal exposure to occupational electromagnetic radiation with the sex ratio of the offspring. We conducted a meta-analysis on their correlation using Stata 11.0. There was no statistically significant difference in the sex ratio between the offspring with paternal exposure to occupational electromagnetic radiation and those without (pooled OR = 1.00 [95% CI: 0.95 -1.05], P = 0.875). Subgroup analysis of both case-control and cohort studies revealed no significant difference (pooled OR = 1.03 [95% CI: 0.99 -1.08], P = 0.104 and pooled OR = 0.98 [95% CI: 0.99 -1.08], P = 0.186, respectively). Paternal exposure to occupational electromagnetic radiation is not correlated with the sex ratio of the offspring.

  8. The sex ratio of siblings of individuals with a history of developmental language disorder

    DEFF Research Database (Denmark)

    Mouridsen, Svend Erik; Hauschild, Karen-Marie

    2010-01-01

    '. The objective of this study was to extend previous studies dealing with the extreme male brain theory and to study the sex ratio (proportion of males) in the siblings of 469 individuals with a developmental language disorder (DLD) who were consecutively assessed in the same clinic during a period of 10 years...

  9. The changing sex ratios at birth during the civil war in Tajikistan: 1992-1997.

    Science.gov (United States)

    Hohmann, Sophie; Roche, Sophie; Garenne, Michel

    2010-11-01

    Sex ratios at birth are known to change during wars or shortly after. This study investigated changes in sex ratios during the civil war that occurred in Tajikistan after the dismantling of the Soviet Union. This civil war was particularly bloody and long lasting, and had many demographic consequences. According to vital registration data, some 27,000 persons died in excess of previous trends during the civil war period (1992-1997), and total mortality was sometimes estimated to be three times higher by independent observers. Birth rates dropped markedly during the war, and sex ratios at birth increased significantly from 104.6 before the war to 106.9 during the war, to return to baseline values afterwards. The change in sex ratio is investigated according to demographic evidence (migration, delayed marriage, spouse separation), substantiated with qualitative evidence (difficulties with food supply), and compared with patterns found in Europe during World War II, as well as with recent wars in the Middle East.

  10. Temporal patterns in capture rate and sex ratio of forest bats in Arkansas

    Science.gov (United States)

    Roger W. Perry; S. Andrew Carter; Ronald E. Thill

    2010-01-01

    We quantified changes in capture rates and sex ratios from May to Sept. for eight species of bats, derived from 8 y of extensive mist netting in forests of the Ouachita Mountains, Arkansas. Our primary goal was to determine patterns of relative abundance for each species of bat captured over forest streams and to determine if these patterns were similar to patterns of...

  11. Evaluation of traps used to monitor southern pine beetle aerial populations and sex ratios

    Science.gov (United States)

    James T. Cronin; Jane L. Hayes; Peter. Turchin

    2000-01-01

    Various kinds of traps have been employed to monitor and forecast population trends of the southern pine beetle (Dendroctonus frontalis Zimmermann; Coleoptera: Scolytidae), but their accuracy in assessing pine-beetle abundance and sex ratio in the field has not been evaluated directly.In trus study, we...

  12. Sex ratio of five species of pelagic copepods from Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswathy, M.; Santhakumari, V.

    Sex ratio in five species from south and southeast coast of India varied remarkably. Five species were selected for the present investigation. Range in the percentage of males was from 8 to 121 in @iUndinula vulgaris@@ (Dana), 16-425 in @i...

  13. Transmission and expression of the parasitic paternal sex ratio (PSR) chromosome

    NARCIS (Netherlands)

    Beukeboom, Leo W.; Werren, John H.

    1993-01-01

    B-chromosomes are often considered genomic parasites. They are extra to the normal chromosomal complement, are unnecessary for survival of an individual, and are often inherited at higher than Mendelian rates. Paternal Sex Ratio (PSR) is an extreme example of a parasitic B-chromosome in the wasp

  14. Mapping of paternal-sex-ratio deletion chromosomes localizes multiple regions involved in expression and transmission

    NARCIS (Netherlands)

    McAllister, BF; Beukeboom, LW; Werren, JH

    The paternal-sex-ratio (PSR) chromosome in the parasitic wasp Nasonia vitripennis is a submetacentric supernumerary (B chromosome). Males transmit PSR, but after fertilization it causes the loss of the paternal autosomes. Paternal genome loss caused by PSR results in the conversion of a female

  15. The paternal-sex-ratio (PSR) chromosome in natural populations of Nasonia (Hymenoptera Chalcidoidea)

    NARCIS (Netherlands)

    Beukeboom, L.W.; Werren, J.H.

    2000-01-01

    Selfish genetic elements may be important in promoting evolutionary change. Paternal sex ratio (PSR) is a selfish B chromosome that causes all-male families in the haplodiploid parasitic wasp Nasonia vitripennis, by inducing paternal genome loss in fertilized eggs. The natural distribution and

  16. The sex ratio of offspring is associated with the mothers' age at menarche

    DEFF Research Database (Denmark)

    Fukuda, Misao; Fukuda, Kiyomi; Shimizu, Takashi

    2011-01-01

    BACKGROUND Early menarcheal age is a risk factor for breast and ovarian cancers and is also associated with an increased spontaneous abortion rate. The aim of this study was to investigate whether there is a link between early menarcheal age and the offspring sex ratio. METHODS We recorded the sex...... years) and to the number of infants per woman (i.e. fertility index). RESULTS A low offspring sex ratio (males/females) of 0.800 was observed in mothers who entered menarche at the age of 9 years; the odds ratio (OR) (95% confidence intervals) compared with those of control group with menarche at age 14...... of 21208 live born infants, all singletons, born to 10 847 premenopausal women (mean attending age: 37.5 ± 7.2 years, range 22-54) who attended our clinics for obstetrical and gynaecological assessment. We calculated the sex ratio of newborn infants in relation to the mothers' age of menarche (from 9 to 18...

  17. Seasonal variation in Eurasian Wigeon Anas penelope sex and age ratios from hunter-based surveys

    DEFF Research Database (Denmark)

    Clausen, Kevin Kuhlmann; Dalby, Lars; Sunde, Peter

    2013-01-01

    schemes. This study found consistent seasonal variation in Eurasian Wigeon Anas penelope sex and age ratios among Danish hunter-based wing surveys, and describes how accounting for this variation might explain reported discrepancies between this and other monitoring methods. Early season flocks were...

  18. The variations of human sex ratio at birth during and after wars, and their potential explanations.

    Science.gov (United States)

    James, William H

    2009-03-07

    Data on wartime sex ratios (proportions male at birth) are reviewed. Two sorts of variation are empirically well supported viz. (a) rises during and just after both World Wars and (b) a fall in Iran during the Iran-Iraq War. Potential explanations are offered here for these rises and fall. The fall seems plausibly explained by psychological stress causing pregnant women disproportionately to abort male fetuses. The rises may be explained by either or both of two different forms of hypothesis viz. (i) Kanazawa's "returning soldier" hypothesis and (ii) variation in coital rates. The coital rate hypothesis potentially accounts, in slightly different ways, for the rises both during, and just after, some wars. The argument that coital rate affects sex ratio just after wars seems to be supported by evidence that in some combatant countries, dizygotic (DZ) twinning rates (which also reportedly vary with coital rate) peaked after the World Wars. The suggestion that war is associated with rises in sex ratio at birth was first made more than two centuries ago. However, I have been unable to locate direct supporting sex ratio data relating to any conflict before World War One. So it would be useful if historical demographers were to search for such data relating to these earlier wars.

  19. Spatial-temporal variation in sex ratio and group size of ostriches ...

    African Journals Online (AJOL)

    Struthio camelus) in Serengeti National Park and adjacent partially protected areas in northern Tanzania. Data were collected for two years (2005- 2006), along 388 km of roads. The two areas were compared with respect to ostrich sex ratio (male: ...

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

    Science.gov (United States)

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

    2011-10-01

    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.

  1. Sex ratio and women's career choice: Does a scarcity of men lead women to choose briefcase over baby?

    NARCIS (Netherlands)

    Durante, K.D.; Griskevicius, V.; Simpson, J.A.; Cantu, S.M.; Tybur, J.M.

    2012-01-01

    Although the ratio of males to females in a population is known to influence behavior in nonhuman animals, little is known about how sex ratio influences human behavior. We propose that sex ratio affects women's family planning and career choices. Using both historical data and experiments, we

  2. Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

    DEFF Research Database (Denmark)

    Timmermann, Clara Amalie Gade; Choi, Anna L; Petersen, Maria Skaalum

    2017-01-01

    or umbilical cord blood. Confounder adjusted logistic regression models were used to assess the associations between maternal exposures and the secondary sex ratio. A doubling in ΣPCB, p,p'-DDE and mercury concentrations were associated with increased odds by 8% (95% CI = 0-16%), 7% (95% CI = 0-14%) and 9% (95......This study was undertaken to assess the potential impact of maternal exposures to polychlorinated biphenyl (PCB), dichlorodiphenyl dichloroethylene (DDE) and methylmercury on the secondary sex ratios (the ratio of male to female live births) over a span of 23 years. The study includes prospective...... data from three Faroese birth cohorts, with a total of 2,152 healthy mother-child dyads recruited between 1986 and 2009. The Faroe Islands is a subarctic fishing community, where pilot whale meat and blubber are part of the traditional marine diet. Exposures were measured in maternal hair, serum...

  3. Temperature-induced sex reversal is not responsible for sex-ratio distortions in grayling Thymallus thymallus or brown trout Salmo trutta.

    Science.gov (United States)

    Pompini, M; Buser, A M; Thali, M R; Von Siebenthal, B A; Nusslé, S; Guduff, S; Wedekind, C

    2013-08-01

    On the basis of the experiments carried out over various years, it was concluded that (1) grayling Thymallus thymallus and brown trout Salmo trutta are resistant to temperature-induced sex reversal at ecologically relevant temperatures, (2) environmental sex reversal is unlikely to cause the persistent sex ratio distortion observed in at least one of the study populations and (3) sex-specific tolerance of temperature-related stress may be the cause of distorted sex ratios in populations of T. thymallus or S. trutta. © 2013 The Fisheries Society of the British Isles.

  4. Use of 2D:4D digit ratios to determine sex.

    Science.gov (United States)

    Barrett, Christopher K; Case, D Troy

    2014-09-01

    Second to fourth digit ratios (2D:4D) are sexually dimorphic in human hands and established by the 13th gestational week. Application of 2D:4D for determining sex in living individuals by Kanchan et al. (Forensic Sci Int, 181, 2008, 53.e1) produced classification rates of 80% for males and 74-78% for females. Few studies have explored the use of 2D:4D for sexing skeletal remains. We test estimated finger lengths, phalanx lengths, and 2D:4D derived from hand bones for determining sex. Maximum phalanx length was collected using a mini-osteometric board from 451 individuals of known age, sex, and ancestry in four skeletal collections. Logistic regression of 2nd and 4th digit finger and phalanx lengths produced classification rates greater than 80%. Digit ratios, however, failed to reach classification rates greater than 59%. Our results support those of Voracek (Forensic Sci Int, 185, 2009, e29) and suggest that 2D:4D may be population-specific and thus inappropriate for universal application as a means of determining sex. © 2014 American Academy of Forensic Sciences.

  5. IMBALANCED SEX RATIOS, MEN’S SEXUAL BEHAVIOR, AND STI RISK IN CHINA*

    Science.gov (United States)

    South, Scott J.; Trent, Katherine

    2011-01-01

    China has been experiencing pronounced changes in its sex ratio, but little research has explored the consequences of these changes for sexual behavior and health. We merge data from the 1999–2000 Chinese Health and Family Life Survey with community-level data from the 1982, 1990, and 2000 Chinese censuses to examine the relationship between the local sex ratio and several dimensions of men’s sexual behavior and sexual health. Multilevel logistic regression models show that, when faced with a relative abundance of age-matched women in their community, Chinese men are slightly less likely to have intercourse with commercial sex workers, but are more likely to engage in premarital noncommercial intercourse and to test positive for a sexually-transmitted infection (STI). These findings are consistent with hypotheses derived from demographic-opportunity theory, which suggests that an abundance of opposite-sex partners will increase the risk of early, frequent, and multi-partner sex and, through this, STI risk. PMID:21131616

  6. Crowd control: sex ratio affects sexually selected cuticular hydrocarbons in male Drosophila serrata.

    Science.gov (United States)

    Gershman, S N; Rundle, H D

    2017-03-01

    Although it is advantageous for males to express costly sexually selected signals when females are present, they may also benefit from suppressing these signals to avoid costly interactions with rival males. Cuticular chemical profiles frequently function as insect sexual signals; however, few studies have asked whether males alter these signals in response to their social environment. In Drosophila serrata, an Australian fly, there is sexual selection for a multivariate combination of male cuticular hydrocarbons (CHCs). Here, we show that the ratio of females to males that an adult male experiences has a strong effect on his CHC expression, with female-biased adult sex ratios eliciting greater expression of CHC profiles associated with higher male mating success. Classical models predict that male reproductive investment should be highest when there is a small but nonzero number of rivals, but we found that males expressed the most attractive combination of CHCs when there were no rivals. We found that male CHCs were highly sensitive to adult sex ratio, with males expressing higher values of CHC profiles associated with greater mating success as the ratio of females to males increased. Moreover, sex ratio has a stronger effect on male CHC expression than adult density. Finally, we explore whether sex ratio affects the variance among a group of males in their CHC expression, as might be expected if individuals respond differently to a given social environment, but find little effect. Our results reveal that subtle differences in social environment can induce plasticity in male chemical signal expression. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  7. National, regional, and global sex ratios of infant, child, and under-5 mortality and identification of countries with outlying ratios: a systematic assessment.

    Science.gov (United States)

    Alkema, Leontine; Chao, Fengqing; You, Danzhen; Pedersen, Jon; Sawyer, Cheryl C

    2014-09-01

    Under natural circumstances, the sex ratio of male to female mortality up to the age of 5 years is greater than one but sex discrimination can change sex ratios. The estimation of mortality by sex and identification of countries with outlying levels is challenging because of issues with data availability and quality, and because sex ratios might vary naturally based on differences in mortality levels and associated cause of death distributions. For this systematic analysis, we estimated country-specific mortality sex ratios for infants, children aged 1-4 years, and children under the age of 5 years (under 5s) for all countries from 1990 (or the earliest year of data collection) to 2012 using a Bayesian hierarchical time series model, accounting for various data quality issues and assessing the uncertainty in sex ratios. We simultaneously estimated the global relation between sex ratios and mortality levels and constructed estimates of expected and excess female mortality rates to identify countries with outlying sex ratios. Global sex ratios in 2012 were 1·13 (90% uncertainty interval 1·12-1·15) for infants, 0·95 (0·93-0·97) for children aged 1-5 years, and 1·08 (1·07-1·09) for under 5s, an increase since 1990 of 0·01 (-0·01 to 0·02) for infants, 0·04 (0·02 to 0·06) for children aged 1-4 years, and 0·02 (0·01 to 0·04) for under 5s. Levels and trends varied across regions and countries. Sex ratios were lowest in southern Asia for 1990 and 2012 for all age groups. Highest sex ratios were seen in developed regions and the Caucasus and central Asia region. Decreasing mortality was associated with increasing sex ratios, except at very low infant mortality, where sex ratios decreased with total mortality. For 2012, we identified 15 countries with outlying under-5 sex ratios, of which ten countries had female mortality higher than expected (Afghanistan, Bahrain, Bangladesh, China, Egypt, India, Iran, Jordan, Nepal, and Pakistan). Although excess female

  8. Logging affects fledgling sex ratios and baseline corticosterone in a forest songbird.

    Science.gov (United States)

    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.

  9. Malnutrition, sex ratio, and selection: a study based on the great leap forward famine.

    Science.gov (United States)

    Song, Shige

    2014-12-01

    This study tests the evolutionary hypothesis that maternal nutritional condition can influence offspring sex ratio at birth in humans. Using the 1959-1961 Chinese Great Leap Forward famine as a natural experiment, this study combines two large-scale national data sources and difference-in-differences method to identify the effect of famine-induced acute malnutrition on sex ratio at birth. The results show a significant famine-induced decrease in the proportion of male births in the 1958, 1961, and 1964 in the urban population but not in the rural population. Given that both the urban and rural populations suffered from the famine-induced malnutrition, and that the rural population experienced a drastic famine-induced mortality increase and fertility reduction, these results suggest the presence of a short-term famine effect, a long-term famine effect, and a selection effect. The timing of the estimated famine effects suggests that famine influences sex ratio at birth by differential implantation and differential fetal loss by fetal sex.

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

    Science.gov (United States)

    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. © 2015 John Wiley & Sons Ltd.

  11. Changing sex ratio of mortality in the Semai Senoi, 1969-1987.

    Science.gov (United States)

    Fix, A G

    1991-04-01

    An excess of male over female deaths is characteristic of modern national populations, whereas in some high-mortality societies female mortality exceeds that of males. Among the Semai Senoi, a Malaysian Orang Asli ("aboriginal") population, women experienced higher mortality than males in the decades before 1969. This differential occurred in all age classes older than 15 years so that the sex ratio progressively increased with age. A recent (1987) restudy of the Semai population found that sex-specific differential mortality is much reduced. A comparison of the 1969 and 1987 life tables shows a sharp shift in the sex ratios of mortality for the post-15-year-old age classes (the geometric means of age classes 15-44 were 0.768 in 1969 and 0.997 in 1987) so that male and female expectations of further life at age 15 are now nearly identical. In contrast to the best-known cases of high female mortality (mostly in South Asia), Semai sex differential mortality does not include the childhood ages. The Semai have traditionally been relatively sexually egalitarian, and sex bias in care has not occurred. Analysis of sex-specific causes of death for the pre-1969 population suggests that maternal mortality is the major cause of the excess female deaths. The reduced number of maternal deaths seems largely due to better health care, particularly the availability of hospital services. Interestingly, the reduction in female mortality has occurred simultaneously with increased fertility, and overall mortality has continued at relatively high levels (eO less than 36). Thus, rather than forming a component of a unitary demographic transition, declining sex differences in mortality can be accounted for by a specific factor, better maternal care.

  12. Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity.

    Science.gov (United States)

    Fawcett, Tim W; Kuijper, Bram; Weissing, Franz J; Pen, Ido

    2011-09-20

    Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because these sons will inherit their father's attractiveness and enjoy high mating success, thereby yielding greater fitness returns than daughters. However, previous research has overlooked the fact that there is a reciprocal feedback from life-history strategies to sexual selection. Here, using a simple mathematical model, we show that if mothers adaptively control offspring sex in relation to their partner's attractiveness, sexual selection is weakened and male ornamentation declines. This weakening occurs because the ability to determine offspring sex reduces the fitness difference between females with attractive and unattractive partners. We use individual-based, evolutionary simulations to show that this result holds under more biologically realistic conditions. Sexual selection and sex allocation thus interact in a dynamic fashion: The evolution of conspicuous male ornaments favors sex-ratio adjustment, but this conditional strategy then undermines the very same process that generated it, eroding sexual selection. We predict that, all else being equal, the most elaborate sexual displays should be seen in species with little or no control over offspring sex. The feedback process we have described points to a more general evolutionary principle, in which a conditional strategy weakens directional selection on another trait by reducing fitness differences.

  13. Effects of induced abortion and son preference on the imbalance of sex ratio in Korea.

    Science.gov (United States)

    Cho, N H; Hong, M S; Hayashi, K

    1996-01-01

    "This study examines the trend and determinants of pregnancy outcomes in [South] Korea during the period from the early 1960s to the early 1990s using data from a retrospective survey of pregnancies. First, pregnancy outcomes are compared between the subsamples which are divided by the year of pregnancy and by the number of existing children. Within each subsample, comparisons are also made according to premarital pregnancy, sex composition of existing children, women's education level and the place of residence. The following section focuses on the pregnancy outcomes by the contraceptive methods used when one became pregnant. Finally, selective abortions and their implications [for] fertility and the sex ratio are discussed." (EXCERPT)

  14. Causes and consequences of adult sex ratio imbalance in a historical U.S. population.

    Science.gov (United States)

    Schacht, Ryan; Smith, Ken R

    2017-09-19

    The responsiveness of individuals to partner availability has been well-documented across the literature. However, there is disagreement regarding the direction of the consequences of sex ratio imbalance. Specifically, does an excess of males or females promote male-male mating competition? In an attempt to clarify the role of the adult sex ratio (ASR) on behaviour, here we evaluate both competing and complimentary expectations derived from theory across the social and biological sciences. We use data drawn from a historical, nineteenth century population in North America and target several life-history traits thought to be affected by partner availability: age at first birth, relationship status, completed fertility and longevity. Furthermore, we assess the role of various contributors to a population's ASR. We find that both the contributors to and consequences of sex ratio imbalance vary over time. Our results largely support predictions of greater male pairbond commitment and lesser male mating effort, as well as elevated bargaining power of women in response to female scarcity. After reviewing our findings, and others from across the literature, we highlight the need to adjust predictions in response to ASR imbalance by the: (i) culturally mediated mating arena, (ii) variable role of demographic inputs across time and place, (iii) constraints to behavioural outcomes across populations, and (iv) ability and accuracy of individuals to assess partner availability.This article is part of the themed issue 'Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Joanne Braun McNeill

    Full Text Available 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.

  17. INTRASPECIFIC VARIATION IN ANT SEX RATIOS AND THE TRIVERS-HARE HYPOTHESIS.

    Science.gov (United States)

    Boomsma, J J; Grafen, A

    1990-07-01

    We consider worker-controlled sex investments in eusocial Hymenoptera (ants in particular) and assume that relatedness asymmetry is variable among colonies and that workers are able to assess the relatedness asymmetry in their own colony. We predict that such "assessing" workers should maximize their inclusive fitness by specializing in the production of the sex to which they are relatively most related, i.e., colonies whose workers have a relatedness asymmetry below the population average should specialize in males, whereas colonies whose workers have a higher than average relatedness asymmetry should specialize in making females. Our argument yields the expectation that colony sex ratios will be bimodally distributed in ant populations where relatedness asymmetry is variable owing to multiple mating, worker reproduction, and/or polygyny. No such bimodality is expected, however, in ant species where relatedness asymmetry is known to be constant, or in cases where relatedness asymmetry is supposed to be irrelevant due to allospecific brood rearing under queen control, as in the slave-making ants. Comparative data on colony sex ratios in ants are reviewed to test the predictions. The data partly support our contentions, but are as yet insufficient to be considered as decisive evidence. © 1990 The Society for the Study of Evolution.

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Sex Ratio and Twinning in Women with Hyperemesis or Pre-eclampsia

    DEFF Research Database (Denmark)

    Basso, Olga; Olsen, Jørn

    2001-01-01

    We examined twinning and fetal gender in births of women with a hospital diagnosis of pre-eclampsia or hyperemesis. We also investigated sex ratio in infants whose mothers had had hyperemesis or pre-eclampsia in a different pregnancy. From all the hospitalized cases in Denmark between 1980 and 1996...... we extracted 6,227 births with hyperemesis and 24,764 with pre-eclampsia. Twins were more frequent in pregnancies with either condition. The male to female sex ratio was 1.04 (95%CI = 1.02-1.05) in the reference population, 0.87 (95% CI = 0.82-0.91) in births with hyperemesis, and 1.10 (95% CI = 1.......07-1.12) in births with pre-eclampsia. Women with pre-eclampsia had slightly more males also in non-affected pregnancies....

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

    Directory of Open Access Journals (Sweden)

    Peter Biedermann

    2010-09-01

    Full Text Available Strongly female-biased sex ratios are typical for the fungal feeding 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.

  1. Sibling Sex Ratio and Birth Order in Early-Onset Gender Dysphoric Adolescents

    OpenAIRE

    Schagen, Sebastian E. E.; Delemarre-Van De Waal, Henriette A; Blanchard, Ray; Cohen-Kettenis, Peggy T

    2011-01-01

    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 dysphor...

  2. Declined sex ratio at birth in Fallujah (Iraq) during Iraq war with Iran.

    Science.gov (United States)

    Saadat, Mostafa

    2011-01-01

    The main objective of this study was to investigate whether the sex ratio at birth (SRB, male proportion) alter in Iraq during its war against Iran (1980-1988). Here we compared 785 births (348 males, 437 females) during 1980-1989 with 1144 births (655 males, 489 females) before 1980 and 2914 births (1496 males, 1418 females) after 1989 in Fallujah, Iraq. The SRB significantly decreased during 1980-1989 in comparison with the ratios before 1980 (OR=0.595, 95 % CI: 0.495-0.714, PIraq war began at 1980 and ended in 1988, therefore it seems that the SRB decreased in Fallujah (Iraq) during the war.

  3. Gestational dietary protein is associated with sex specific decrease in blood flow, fetal heart growth and post-natal blood pressure of progeny.

    Directory of Open Access Journals (Sweden)

    Juan H Hernandez-Medrano

    Full Text Available The incidence of adverse pregnancy outcomes is higher in pregnancies where the fetus is male. Sex specific differences in feto-placental perfusion indices identified by Doppler assessment have recently been associated with placental insufficiency and fetal growth restriction. This study aims to investigate sex specific differences in placental perfusion and to correlate these changes with fetal growth. It represents the largest comprehensive study under field conditions of uterine hemodynamics in a monotocous species, with a similar long gestation period to the human. Primiparous 14 mo heifers in Australia (n=360 and UK (n=180 were either individually or group fed, respectively, diets with differing protein content (18, 14, 10 or 7% crude protein (CP from 60 d prior to 98 days post conception (dpc. Fetuses and placentae were excised at 98 dpc (n = 48. Fetal development an median uterine artery blood flow were assessed monthly from 36 dpc until term using B-mode and Doppler ultrasonography. MUA blood flow to the male feto-placental unit increased in early pregnancy associated with increased fetal growth. Protein restriction before and shortly after conception (-60 d up to 23 dpc increased MUA diameter and indices of velocity during late pregnancy, reduced fetal heart weight in the female fetus and increased heart rate at birth, but decreased systolic blood pressure at six months of age.Sex specific differences both in feto-placental Doppler perfusion indices and response of these indices to dietary perturbations were observed. Further, maternal diet affected development of fetal cardiovascular system associated with altered fetal haemodynamics in utero, with such effects having a sex bias. The results from this study provide further insight into the gender specific circulatory differences present in the fetal period and developing cardiovascular system.

  4. Sex ratio meiotic drive as a plausible evolutionary mechanism for hybrid male sterility.

    Directory of Open Access Journals (Sweden)

    Linbin Zhang

    2015-03-01

    Full Text Available 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.

  5. WormGender - Open-Source Software for Automatic Caenorhabditis elegans Sex Ratio Measurement.

    Directory of Open Access Journals (Sweden)

    Marta K Labocha

    Full Text Available Fast and quantitative analysis of animal phenotypes is one of the major challenges of current biology. Here we report the WormGender open-source software, which is designed for accurate quantification of sex ratio in Caenorhabditis elegans. The software functions include, i automatic recognition and counting of adult hermaphrodites and males, ii a manual inspection feature that enables manual correction of errors, and iii flexibility to use new training images to optimize the software for different imaging conditions. We evaluated the performance of our software by comparing manual and automated assessment of sex ratio. Our data showed that the WormGender software provided overall accurate sex ratio measurements. We further demonstrated the usage of WormGender by quantifying the high incidence of male (him phenotype in 27 mutant strains. Mutants of nine genes (brc-1, C30G12.6, cep-1, coh-3, him-3, him-5, him-8, skr-1, unc-86 showed significant him phenotype. The WormGender is written in Java and can be installed and run on both Windows and Mac platforms. The source code is freely available together with a user manual and sample data at http://www.QuantWorm.org/. The source code and sample data are also available at http://dx.doi.org/10.6084/m9.figshare.1541248.

  6. Ownership of dwelling affects the sex ratio at birth in Uganda.

    Directory of Open Access Journals (Sweden)

    Bernard Wallner

    Full Text Available BACKGROUND: Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH. This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB on a Ugandan sample. METHODOLOGY/PRINCIPAL FINDINGS: Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019 compared to those who live in non-owned dwellings (0.458. Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers' age, mothers' education, parity and others. CONCLUSIONS/SIGNIFICANCE: The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.

  7. Sex ratio meiotic drive as a plausible evolutionary mechanism for hybrid male sterility.

    Science.gov (United States)

    Zhang, Linbin; Sun, Tianai; Woldesellassie, Fitsum; Xiao, Hailian; Tao, Yun

    2015-03-01

    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.

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

    Science.gov (United States)

    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

  9. Contrasting brood-sex ratio flexibility in two opiine (Hymenoptera: Braconidae) parasitoids of tephritid (Diptera) fruit files

    Science.gov (United States)

    Mass-rearing of fruit fly parasitoids for augmentative release would be more economical if production could be biased towards females. If sex ratios are ever to be manipulated under rearing conditions it is important to determine if, then understand why, sex ratio flexibility exists. Unequal brood-s...

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

    Science.gov (United States)

    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. © 2014 SETAC.

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

    Science.gov (United States)

    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.

  12. How do sex ratios in China influence marriage decisions and intra-household resource allocation?

    Science.gov (United States)

    Porter, Maria

    2017-01-01

    This article examines how imbalanced sex ratios influence marriage decisions and household bargaining. Using data from the 1982 Chinese census, the traditional “availability ratio” is modified to reflect the degree to which men tend to marry women from different cohorts. This ratio reflects the average tendency of men to prefer women who are close in age to women who are several years younger than them by weighting cohort sizes using the proportion of people in the population who marry someone born in a different cohort. Given that men generally marry younger women, this ratio varies independently of the size of one's own birth cohort. Yet, the ratio fluctuates considerably across individuals, as the sizes of birth cohorts in China vary across time and regions. This enables us to examine how variability in such ratios may influence marriage decisions and household bargaining. The findings suggest that women exercise greater bargaining power once married. Results indicate that as women become scarcer in the marriage market, they have healthier sons. Men also delay marriage, and consume less tobacco and alcohol. This paper also highlights how sensitive findings may be to using this modified weighted availability ratio rather than a traditional unweighted availability ratio. PMID:28989332

  13. Temperature-dependent sex determination in fish revisited: prevalence, a single sex ratio response pattern, and possible effects of climate change.

    Directory of Open Access Journals (Sweden)

    Natalia Ospina-Alvarez

    Full Text Available BACKGROUND: In gonochoristic vertebrates, sex determination mechanisms can be classified as genotypic (GSD or temperature-dependent (TSD. Some cases of TSD in fish have been questioned, but the prevalent view is that TSD is very common in this group of animals, with three different response patterns to temperature. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed field and laboratory data for the 59 fish species where TSD has been explicitly or implicitly claimed so far. For each species, we compiled data on the presence or absence of sex chromosomes and determined if the sex ratio response was obtained within temperatures that the species experiences in the wild. If so, we studied whether this response was statistically significant. We found evidence that many cases of observed sex ratio shifts in response to temperature reveal thermal alterations of an otherwise predominately GSD mechanism rather than the presence of TSD. We also show that in those fish species that actually have TSD, sex ratio response to increasing temperatures invariably results in highly male-biased sex ratios, and that even small changes of just 1-2 degrees C can significantly alter the sex ratio from 1:1 (males:females up to 3:1 in both freshwater and marine species. CONCLUSIONS/SIGNIFICANCE: We demonstrate that TSD in fish is far less widespread than currently believed, suggesting that TSD is clearly the exception in fish sex determination. Further, species with TSD exhibit only one general sex ratio response pattern to temperature. However, the viability of some fish populations with TSD can be compromised through alterations in their sex ratios as a response to temperature fluctuations of the magnitude predicted by climate change.

  14. The impact of the stopping rule on sex ratio of last births in Vietnam.

    Science.gov (United States)

    Pham, Bang Nguyen; Adair, Timothy; Hill, Peter S; Rao, Chalapati

    2012-03-01

    This study examines the hypothesis that the stopping rule - a traditional postnatal sex selection method where couples decide to cease childbearing once they bear a son - plays a role in high sex ratio of last births (SRLB). The study develops a theoretical framework to demonstrate the operation of the stopping rule in a context of son preference. This framework was used to demonstrate the impact of the stopping rule on the SRLB in Vietnam, using data from the Population Change Survey 2006. The SRLB of Vietnam was high at the level of 130 in the period 1970-2006, and particularly in the period 1986-1995, when sex-selective abortion was not available. Women were 21% more likely to stop childbearing after a male birth compared with a female birth. The SRLB was highest at parity 2 (138.7), particularly in rural areas (153.5), and extremely high (181.9) when the previous birth was female. Given the declining fertility, the stopping rule has a potential synergistic effect with sex-selective abortion to accentuate a trend of one-son families in the population.

  15. Calcium availability influences litter size and sex ratio in white-footed mice (Peromyscus leucopus.

    Directory of Open Access Journals (Sweden)

    Christina M Schmidt

    Full Text Available 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.

  16. Sex ratio and women's career choice: does a scarcity of men lead women to choose briefcase over baby?

    Science.gov (United States)

    Durante, Kristina M; Griskevicius, Vladas; Simpson, Jeffry A; Cantú, Stephanie M; Tybur, Joshua M

    2012-07-01

    Although the ratio of males to females in a population is known to influence behavior in nonhuman animals, little is known about how sex ratio influences human behavior. We propose that sex ratio affects women's family planning and career choices. Using both historical data and experiments, we examined how sex ratio influences women's career aspirations. Findings showed that a scarcity of men led women to seek high-paying careers and to delay starting a family. This effect was driven by how sex ratio altered the mating market, not just the job market. Sex ratios involving a scarcity of men led women to seek lucrative careers because of the difficulty women have in finding an investing, long-term mate under such circumstances. Accordingly, this low-male sex ratio produced the strongest desire for lucrative careers in women who are least able to secure a mate. These findings demonstrate that sex ratio has far-reaching effects in humans, including whether women choose briefcase over baby. PsycINFO Database Record (c) 2012 APA, all rights reserved

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

    Science.gov (United States)

    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.

  18. Establishing sex ratios of sea turtle foraging populations: validation of a novel testosterone hormone assay technology and sex assessment for five species.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Demographic data are essential for developing sound management and conservation plans for marine turtle populations. Sex ratios, even though they are an essential...

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

    Directory of Open Access Journals (Sweden)

    Joshua H. Temple

    2016-06-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2016-06-17

    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.

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

    Directory of Open Access Journals (Sweden)

    Collette M Thogerson

    Full Text Available 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

  2. Change in offspring sex ratio over a very short season in Lincoln’s Sparrows: the potential role of bill development

    NARCIS (Netherlands)

    Graham, E.B.; Caro, S.P.; Sockman, K.W.

    2011-01-01

    The sex ratios of offspring are targets of natural selection that can affect parental energy expenditure and fitness, adult sex ratios, and population dynamics. Parents may manipulate offspring sex ratios based on sex differences in potential reproductive success. In Lincoln’s Sparrows (Melospiza

  3. Effects of female diet and age on offspring sex ratio of the solitary parasitoid Pachycrepoideus vindemmiae (Rondani (Hymenoptera, Pteromalidae

    Directory of Open Access Journals (Sweden)

    Hao-Yuan Hu

    2012-06-01

    Full Text Available Effects of female diet and age on offspring sex ratio of the solitary parasitoid Pachycrepoideus vindemmiae (Rondani (Hymenoptera, Pteromalidae. Theories predict that females of parasitoid wasps would adjust the offspring sex ratio to environmental conditions in the oviposition patch, but the diet and age of females would also affect the sex ratio adjustment. Our focus was to test the effects of female diet and age on offspring sex ratio of the solitary parasitoid wasp, Pachycrepoideus vindemmiae (Rondani, 1875. Our results showed that females fed with honey had significantly less female biased offspring sex ratio than those fed only with water. Offspring sex ratio (male percentage decreased with female age or female longevity at the beginning of oviposition but increased at the end. There should be a sperm limitation in P. vindemmiae females at the end of oviposition, and a higher frequency of unfertilized eggs were laid then. Females also laid more unfertilized eggs at the beginning of oviposition, which would be necessary to insure the mating among offspring. Male offspring developed faster and emerged earlier, which would also reduce the risk of virginity in offspring with female-biased sex ratio.

  4. The sex ratio at birth in South Africa increased 9months after the 2010 FIFA World Cup.

    Science.gov (United States)

    Masukume, Gwinyai; Grech, Victor

    2015-12-01

    In humans in the absence of significant stress the sex ratio at birth [males/(males+females)] is in favor of more male than female live births. This study sought to determine the influence of the 2010 Fédération Internationale de Football Association (FIFA) World Cup in South Africa on the sex ratio at birth in that country specifically 9months afterwards. Publicly available data from Statistics South Africa was utilized detailing recorded live births. Analysis was carried out by Chi-squared tests. February and March 2011 about 9months after the World Cup, had the highest observed sex ratio at birth (relatively more male births) of 0.5063 for the period 2003 to 2012. The observed sex ratio at birth in the considered two months of 2011 was 0.63% (p=0.02) greater than the sex ratio at birth for corresponding periods from 2008 to 2012. The increase noted in 2011 corresponds to more than 1000 extra male births than expected for February and March 2011. The 2010 FIFA World Cup was followed about 9months afterwards by a significant increase in the sex ratio at birth. The main mechanism driving the observed increase in the sex ratio at birth in South Africa is most likely more frequent sexual intercourse at population level during the tournament. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  5. Sex ratio of newborn infants born to pregnant women with severe chronic constipation

    Directory of Open Access Journals (Sweden)

    Andrew E Czeizel

    2010-09-01

    Full Text Available Andrew E Czeizel1, Erzsébet H Puhó1, Ferenc Bánhidy21Foundation for the Community Control of Hereditary Diseases, 2Second Department of Obstetrics and Gynecology, Semmelweis University, School of Medicine, Budapest, HungaryAbstract: There was a significant male excess in the newborns of pregnant women with severe chronic constipation during pregnancy compared to pregnant women without constipation and pregnant women with new onset severe constipation, during pregnancy.Keywords: constipation, pregnancy, birth outcomes, sex ratio, male excess

  6. Sex Ratio Imbalances Among Children At Micro-Level: China And India Compared.

    OpenAIRE

    Guilmoto, Christophe,; Oliveau, Sébastien

    2007-01-01

    Sex ratio imbalances found in Asia are primarily due to the increasing proportions of sons among children in China and India: the level of gender discrimination in several regions of East China and Northwest India may be extremely pronounced and tends to display a high level of spatial concentration. Comparable data from the last censuses (2000, 2001) can be mapped at the local level, using counties (xian) for China and sub-district units (tahsil, taluk, etc.) for India. In this paper, we fir...

  7. CHANGES IN SEX RATIO AT BIRTH IN CHINA: A DECOMPOSITION BY BIRTH ORDER

    OpenAIRE

    Jiang, Quanbao; Yu, Qun; YANG, SHUCAI; Jesús J. Sánchez-Barricarte

    2016-01-01

    The long-term high sex ratio at birth (SRB) is a serious issue in China. In this study, changes in SRB were decomposed into variations in SRB by birth order and compositional changes in female births by birth order. With SRB data from China’s surveys and censuses, and SRB data from South Korea’s vital registration and censuses from 1980–2015, the trend and decomposition results in SRB were compared between China and South Korea, and the decomposition results for urban and rural SRBs, and for ...

  8. Optimization of Sex Ratio in a Selection Plan for Palas Prolificacy Line

    Directory of Open Access Journals (Sweden)

    Răzvan Popa

    2011-05-01

    Full Text Available The aim of the paper work is to optimize the sex ratio in a selection plan, according to model developed by King (1961, which will be proposed to be applied for prolificacy improvement in Prolific Line Palas. The method used in this paper work is modeling, which exist in the most animal breeding scientifically papers. After the simulations, we observed that the most convenient variant was that which prefigure use of 13 rams on reproduction activity. This variant offer a genetic gain per generation by 0.47497 additive standard deviations.

  9. The effects of sex-ratio and density on locomotor activity in the house fly, Musca domestica

    DEFF Research Database (Denmark)

    Bahrndorff, Simon; Kjaersgaard, Anders; Pertoldi, Cino

    2012-01-01

    Although locomotor activity is involved in almost all behavioral traits, there is a lack of knowledge on what factors affect it. This study examined the effects of sex-ratio and density on the circadian rhythm of locomotor activity of adult Musca domestica L. (Diptera: Muscidae) using an infra...... with and without the presence of females. Overall, this study demonstrates that locomotor activity in M. domestica is affected by sex-ratio and density. Furthermore, the predictability of locomotor activity is affected by both sex-ratio, density, and circadian rhythm. These results add to our understanding...

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

    Science.gov (United States)

    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.

  11. SEX RATIOS OF MOSQUITOES FROM LONG-TERM CENSUSES OF FLORIDA TREE HOLES

    Science.gov (United States)

    Lounibos, L. Philip; Escher, Richard L.

    2008-01-01

    Pupal sexes of the most common mosquito species were determined in the course of biweekly censuses (with replacement) of the contents of 3–7 tree holes from 1980–2003 in Vero Beach, FL. A significant (P Toxorhynchites rutilus or Ae. albopictus, the latter species occurring in this community only since 1991. Although pupae of Ae. triseriatus were recorded during every month of the year, significant male biases were detected only in February–May, August, and December. These results are interpreted in the context of multivoltinism and the previously documented differential sensitivity of male and female eggs of this species to hatching stimuli. Sex-specific responses to hatching stimuli are judged to be present but less pronounced in eggs of Ae. albopictus. Male biases in container Aedes are likely associated with sexual selection, which may also explain seasonal changes in sex ratios, whereby early males compete to mate with high-fecundity females. The overproduction of Ae. triseriatus males may be counterbalanced by increased fitness of females, which are known to predominate in delayed hatches. PMID:18437808

  12. Female-biased sex ratio, polygyny, and persistence in the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus)

    Science.gov (United States)

    Kus, Barbara E.; Howell, Scarlett; Wood, Dustin A.

    2017-01-01

    Demographic changes in populations, such as skewed sex ratios, are of concern to conservationists, especially in small populations in which stochastic and other events can produce declines leading to extirpation. We documented a decline in one of the few remaining populations of Southwestern Willow Flycatcher (Empidonax traillii extimus) in southern California, USA, which dropped from 40 to 5 adults between 2000 and 2015. Declines were unequal between sexes (94% for males, 82% for females). Adult sex ratios were female-biased in 10 of 16 yr. The proportion of paired males that were polygynous ranged from 0% to 100%, depending on the ratio of females to males in the adult population. Some males paired with up to 5 females simultaneously. We investigated the role of nestling sex ratio in the female-biased adult sex ratio by using genetic techniques to determine sex from blood samples collected from 162 nestlings in 72 nests from 2002 to 2009. Both population-level and within-brood nestling sex ratios were female-biased, and were not influenced by nest order (first or subsequent), parental mating type (monogamous or polygynous), or year. Disproportionately more females than males were recruited into the breeding population, mirroring nestling and fledgling sex ratios. It thus appears that a skewed nestling sex ratio has contributed to a female-biased adult population, which in turn has influenced mating behavior. We propose that the capacity for polygyny, which generally occurs at low levels in Southwestern Willow Flycatchers, has allowed this population to persist through a decline that might otherwise have resulted in extinction.

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

    Directory of Open Access Journals (Sweden)

    Grayson Kristine L

    2012-09-01

    Full Text Available Abstract 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

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

    Directory of Open Access Journals (Sweden)

    Doug P Vanderlaan

    Full Text Available 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.

  15. Translocations and sex ratio distortion in the onion fly, Hylemya antiqua (Meigen), and their relevance to genetic control

    NARCIS (Netherlands)

    Vosselman, L.

    1980-01-01

    Experiments on sex determination of the onion fly, Hylemya antiqua (Meigen), are reported in the first two chapters. The main purpose was to establish if the sex ratio distortion observed in certain crosses, was based on a mechanism which could be used for genetic purposes. Two

  16. Deletion analysis of the selfish B chromosome, Paternal Sex Ratio (PSR), in the parasitic wasp Nasonia vitripennis

    NARCIS (Netherlands)

    Beukeboom, Leo W.; Werren, John H.

    1993-01-01

    Paternal Sex Ratio (PSR) is a “selfish” B chromosome in the parasitoid wasp Nasonia vitripennis. It is transmitted via sperm, but causes supercondensation and destruction of the paternal chromosomes in early fertilized eggs. Because this wasp has haplodiploid sex determination, the effect of PSR is

  17. The Sex Ratio of Full and Half Siblings of People Diagnosed With ADHD in Childhood and Adolescence

    DEFF Research Database (Denmark)

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

    2014-01-01

    Objective:It has been suggested that high levels of prenatal testosterone exposure are implied in the etiology of male preponderance disorders such as autism spectrum disorder and ADHD. Within this scope, we studied the sex ratio (proportion of males) in siblings of individuals diagnosed with ADHD...... in childhood and adolescence. Method: We did a nationwide, register-based cohort study of the sex ratio in siblings of the 16,381 patients in Denmark diagnosed with ADHD at age 17 years and younger and registered in the nationwide Danish Psychiatric Central Register between January 1, 1994 and May 28, 2013....... Results: Among the 33,151 siblings, 17,041 were males and 16,110 females. This yields a sex ratio of 0.514, which is not statistically significant different from the Danish live birth sex ratio of 0.513 during the relevant years (p = .70). Conclusion: These findings provide no support for the hypothesis...

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

    Science.gov (United States)

    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. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Does famine influence sex ratio at birth? Evidence from the 1959-1961 Great Leap Forward Famine in China

    National Research Council Canada - National Science Library

    Shige Song

    2012-01-01

    ... sample survey in 1982. The study identified an abrupt decline in sex ratio at birth between April 1960, over a year after the Great Leap Forward Famine began, and October 1963, approximately 2 years after the famine ended...

  20. Local mate competition and transmission bottlenecks: a new model for understanding malaria parasite and other sex ratios.

    Science.gov (United States)

    Neal, Allison T; Taylor, Peter D

    2014-12-21

    The local mate competition model from sex ratio theory predicts female-biased sex ratios in populations that are highly subdivided during mating, and is thought to accord well with the population structure of malaria parasites. However, the selective advantage of female-biased sex ratios comes from the resulting increase in total reproductive output, an advantage the transmission biology of malaria parasite likely reduces. We develop a mathematical model to determine how bottlenecks in transmission that cause diminishing fitness returns from female production affect sex ratio evolution. We develop four variations of this model that incorporate whether or not parasite clones have the ability to detect others that occupy the same host and whether or not the number of clones affects the total mating population size. Our model indicates that transmission bottlenecks favor less female-biased sex ratios than those predicted under LMC. This effect is particularly pronounced if clones have no information about the presence of coexisting clones and the number of mating individuals per patch is fixed. The model could extend our understanding of malaria parasite sex ratios in three main ways. First, it identifies inconsistencies between the theoretical predictions and the data presented in a previous study, and proposes revised predictions that are more consistent with underlying biology of the parasite. Second, it may account for the positive association between parasite density and sex ratio observed within and between some species. Third, it predicts a relationship between mortality rates in the vector and sex ratios, which appears to be supported by the little existing data we have. While the inspiration for this model came from malaria parasites, it should apply to any system in which per capita dispersal success diminishes with increasing numbers of females in a patch. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  2. The sex ratio at birth in France was unchanged 9months after the 1998 FIFA World Cup.

    Science.gov (United States)

    Masukume, Gwinyai; Grech, Victor

    2016-08-01

    Positive psychological phenomena such as increased feelings of belonging linked to hosting the FIFA World Cup were observed in France 1998 and South Africa 2010. Approximately nine months after South Africa hosted the 2010 World Cup the sex ratio at birth increased significantly. Given the similarity of positive psychological phenomena between the two countries, this study sought to determine if the sex ratio at birth increased in France circa nine months after the 1998 World Cup. Anonymized publicly available live birth data from 1994 to 2004 inclusive was obtained from the Insee (Institut National de la Statistique et des Etudes/Économiques - National Institute of Statistics and Economic Studies). For statistical analysis, chi-squared tests were used. The sex ratio at birth for March and April 1999 did not differ significantly from that of the rest of same period from 1996 to 2000 (p=0.558), there was also no significant difference for February and March 1999. The sex ratio at birth did not increase in France after it hosted the 1998 World Cup. Possible reasons why the sex ratio at birth did not increase as it did in South Africa include a higher French prevalence of modern contraceptive use and a different kind/level of excitement for the World Cup in France since it has previously hosted large international sports tournaments. The influence of the World Cup on the sex ratio at birth depends on the context of a specific country. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Flow cytometric sexing of spider sperm reveals an equal sperm production ratio in a female-biased species

    DEFF Research Database (Denmark)

    Vanthournout, Bram; Deswarte, K; Hammad, H

    2014-01-01

    that other factors influence sex ratio variation. In this paper, we investigate whether this additional variation can be explained by the unequal production of male- and female-determining sperm cells during sperm production. Using flow cytometry, we show that males produce equal amounts of male- and female......-determining sperm cells; thus bias in sperm production does not contribute to the sex ratio bias observed in this species. This demonstrates that other factors such as parental genes suppressing endosymbiont effects and cryptic female choice might play a role in sex allocation in this species....

  4. Reproductive seasonality, sex ratio and philopatry in Argentina's common vampire bats

    Science.gov (United States)

    Delpietro, H. A.; Russo, R. G.; Lord, R. D.; Delpietro, G. L.

    2017-01-01

    Common vampire bats (Desmodus rotundus) are a key rabies vector in South America. Improved management of this species requires long-term, region-specific information. To investigate patterns of demography and dispersal, we analysed 13 642 captures of common vampire bats in Northern Argentina from the period 1969–2004. In contrast with findings from more tropical regions, we found reproductive seasonality with peak pregnancy in September and peak lactation in February. Curiously, sex ratios were consistently male-biased both in maternity roosts and at foraging sites. Males comprised 57% of 9509 adults caught at night, 57% of 1078 juveniles caught at night, 57% of 603 juveniles caught in roosts during the day, and 55% of 103 newborns and mature fetuses. Most observed roosts were in man-made structures. Movements of 1.5–54 km were most frequent in adult males, followed by young males, adult females and young females. At night, males visited maternity roosts, and non-pregnant, non-lactating females visited bachelor roosts. Males fed earlier in the night. Finally, we report new longevity records for free-ranging vampire bats: 16 and 17 years of age for a female and male, respectively. Our results are consistent with model predictions that sex-biased movements might play a key role in rabies transmission between vampire bat populations. PMID:28484615

  5. Reproductive seasonality, sex ratio and philopatry in Argentina's common vampire bats.

    Science.gov (United States)

    Delpietro, H A; Russo, R G; Carter, G G; Lord, R D; Delpietro, G L

    2017-04-01

    Common vampire bats (Desmodus rotundus) are a key rabies vector in South America. Improved management of this species requires long-term, region-specific information. To investigate patterns of demography and dispersal, we analysed 13 642 captures of common vampire bats in Northern Argentina from the period 1969-2004. In contrast with findings from more tropical regions, we found reproductive seasonality with peak pregnancy in September and peak lactation in February. Curiously, sex ratios were consistently male-biased both in maternity roosts and at foraging sites. Males comprised 57% of 9509 adults caught at night, 57% of 1078 juveniles caught at night, 57% of 603 juveniles caught in roosts during the day, and 55% of 103 newborns and mature fetuses. Most observed roosts were in man-made structures. Movements of 1.5-54 km were most frequent in adult males, followed by young males, adult females and young females. At night, males visited maternity roosts, and non-pregnant, non-lactating females visited bachelor roosts. Males fed earlier in the night. Finally, we report new longevity records for free-ranging vampire bats: 16 and 17 years of age for a female and male, respectively. Our results are consistent with model predictions that sex-biased movements might play a key role in rabies transmission between vampire bat populations.

  6. Unifying cornerstones of sexual selection: operational sex ratio, Bateman gradient and the scope for competitive investment.

    Science.gov (United States)

    Kokko, Hanna; Klug, Hope; Jennions, Michael D

    2012-11-01

    What explains variation in the strength of sexual selection across species, populations or differences between the sexes? Here, we show that unifying two well-known lines of thinking provides the necessary conceptual framework to account for variation in sexual selection. The Bateman gradient and the operational sex ratio (OSR) are incomplete in complementary ways: the former describes the fitness gain per mating and the latter the potential difficulty of achieving it. We combine this insight with an analysis of the scope for sexually selected traits to spread despite naturally selected costs. We explain why the OSR sometimes does not affect the strength of sexual selection. An explanation of sexual selection becomes more logical when a long 'dry time' ('time out', recovery after mating due to e.g. parental care) is understood to reduce the expected time to the next mating when in the mating pool (i.e. available to mate again). This implies weaker selection to shorten the wait. An integrative view of sexual selection combines an understanding of the origin of OSR biases with how they are reflected in the Bateman gradient, and how this can produce selection for mate acquisition traits despite naturally selected costs. © 2012 Blackwell Publishing Ltd/CNRS.

  7. Education and gender bias in the sex ratio at birth: evidence from India.

    Science.gov (United States)

    Echávarri, Rebeca A; Ezcurra, Roberto

    2010-02-01

    This article investigates the possible existence of a nonlinear link between female disadvantage in natality and education. To this end, we devise a theoretical model based on the key role of social interaction in explaining people's acquisition of preferences, which justifies the existence of a nonmonotonic relationship between female disadvantage in natality and education. The empirical validity of the proposed model is examined for the case of India, using district-level data. In this context, our econometric analysis pays particular attention to the role of spatial dependence to avoid any potential problems of misspecification. The results confirm that the relationship between the sex ratio at birth and education in India follows an inverted U-shape. This finding is robust to the inclusion of additional explanatory variables in the analysis, and to the choice of the spatial weight matrix used to quantify the spatial interdependence between the sample districts.

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

    OpenAIRE

    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 e...

  9. Parental behaviour is unrelated to experimentally manipulated great tit brood sex ratio

    NARCIS (Netherlands)

    Lessells, C.M.; Oddie, K.R.; Mateman, A.C.

    1998-01-01

    Parental investment may be biased with respect to parental sex or offspring sex or there may be an interaction between parental and offspring sex. We investigated whether any of these types of bias occurred in great tits, Parus major. By sexing chicks using random amplified polymorphic DNA (RAPD)

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

    Directory of Open Access Journals (Sweden)

    Hohmann SA

    2014-10-01

    Full Text Available Sophie A Hohmann,1 Cécile A Lefèvre,2,3 Michel L Garenne4–61CNRS, CERCEC, Paris, France; 2Université Paris Descartes, UMR CEPED, PRES Sorbonne Paris Cité, Paris, France; 3INED, Paris, France; 4Institut Pasteur, Epidémiologie des Maladies Emergentes, Paris, France; 5IRD, UMI Résiliences, Bondy, France; 6Medical Research Council/Wits Rural Public Health and Health Transitions Research Unit (Agincourt, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South AfricaAbstract: 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.Keywords: sex-selective abortion, sex-screening methods, value of children, demand for children, sex-preference, Southern Caucasus

  11. The effect of size and sex ratio experiences on reproductive competition in Nicrophorus vespilloides burying beetles in the wild.

    Science.gov (United States)

    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. © 2016 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.

  12. Phenotypic plasticity in response to the social environment: effects of density and sex ratio on mating behaviour following ecotype divergence.

    Directory of Open Access Journals (Sweden)

    Kristina Karlsson

    Full Text Available The ability to express phenotypically plastic responses to environmental cues might be adaptive in changing environments. We studied phenotypic plasticity in mating behaviour as a response to population density and adult sex ratio in a freshwater isopod (Asellus aquaticus. A. aquaticus has recently diverged into two distinct ecotypes, inhabiting different lake habitats (reed Phragmites australis and stonewort Chara tomentosa, respectively. In field surveys, we found that these habitats differ markedly in isopod population densities and adult sex ratios. These spatially and temporally demographic differences are likely to affect mating behaviour. We performed behavioural experiments using animals from both the ancestral ecotype ("reed" isopods and from the novel ecotype ("stonewort" isopods population. We found that neither ecotype adjusted their behaviour in response to population density. However, the reed ecotype had a higher intrinsic mating propensity across densities. In contrast to the effects of density, we found ecotype differences in plasticity in response to sex ratio. The stonewort ecotype show pronounced phenotypic plasticity in mating propensity to adult sex ratio, whereas the reed ecotype showed a more canalised behaviour with respect to this demographic factor. We suggest that the lower overall mating propensity and the phenotypic plasticity in response to sex ratio have evolved in the novel stonewort ecotype following invasion of the novel habitat. Plasticity in mating behaviour may in turn have effects on the direction and intensity of sexual selection in the stonewort habitat, which may fuel further ecotype divergence.

  13. Biased sex-ratio and sex-biased heterozygote disadvantage affect the maintenance of a genetic polymorphism and the properties of hybrid zones.

    Science.gov (United States)

    Nouvellet, P; Gourbière, S

    2013-08-01

    The evolution of biodiversity is a major issue of modern biology, and it is becoming increasingly topical as the ongoing erosion of diversity puts serious threats on human well-being. An elementary mechanism that allows maintaining diversity is the interplay between dispersal and heterozygote selective disadvantage, which can lead to self-sustainable spatial genetic structures and is central to the stability of hybrid zones. Theoretical studies supporting the importance of this mechanism assume a balanced sex-ratio and a heterozygote disadvantage equally affecting both sexes, despite the multiplicity of empirical evidence that (i) adult sex-ratio is usually biased towards either male or female and that (ii) heterozygote disadvantage often affects a single sex. We expanded the existing theory by weighting the strength of selection against heterozygote according to the biased in sex-ratio and in heterozygote disadvantage. The range of conditions allowing for the maintenance of polymorphism can then either double or vanish. We discuss the implications of such finding for birds, mammals and insects diversity. Finally, we provide simple analytical predictions about the effect of those biased on the width and speed of hybrid zones and on the time for the spread of beneficial mutations through such zones. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  14. Norethindrone-induced masculinization and progeny testing in guppy, Poecilia reticulata (Peters 1859).

    Science.gov (United States)

    Basavaraja, N; Chandrashekhara, B H; Ahamad, Rather Mansoor

    2014-03-01

    Norethindrone(NE) was evaluated for its efficacy on alteration of sex ratio of P. reticulata. Either the young fry or the brooders and the resultant fry were fed a commercial diet incorporated with NE at 0, 25, 50, 75 and 100 mg kg(-1) diet (ppm) for 30-40 d in rectangular glass aquaria; this was followed by 40-60 d rearing on NE-free diet in out-door concrete tanks. In general, the androgen treatment altered sex ratio, leading to the production of a dose dependent increase in the percentage of males. The oral administration of the steroid at 75 ppm for 40 d or 100 ppmfor 30 or 40 d to first feeding fry, yielded 100% males. On the other hand, NE administration to brooders before parturition and the resultant fry also produced an all-male population of guppy. The sex ratio of the untreated control was almost 1:1. The survival of fish in all the trials was high, ranging between 67 and 100%. Mating masculinized males ("XX" male) with normal female resulted in an all-female progeny, while crossing normal male (XY) from treatment groups with normal female sired normal sex ratio (1:1), elucidating XX-XY sex determination system in the guppy.

  15. Mapping Causes and Implications of India’s Skewed Sex Ratio and Poverty problem using Fuzzy & Neutrosophic Relational Maps

    OpenAIRE

    Gaurav; Kanika Bhutani; Megha Kumar; Swati Aggarwal

    2016-01-01

    Numerous studies by different researchers have confirmed that skewed sex ratio is a critical social problem in India. This enduring problem of gender imbalance is the collective result of factors like sex selective abortion, gender discrimination, son preference for the preservation of tribe, emergence of new technologies in medical field and many more factors. Another severe problem to be addressed in India is poverty. Many factors contribute to the perpetuation of poverty such as illiteracy...

  16. Effects of gamma radiation on development, sterility, fecundity, and sex ratio of Dermanyssus gallinae (DeGeer) (Acari: Dermanyssidae)

    Energy Technology Data Exchange (ETDEWEB)

    Entrekin, D.L.; Oliver, J.H. Jr.; Pound, J.M.

    1987-06-01

    Protonymphal Dermanyssus gallinae were irradiated with 0.50, 0.75, 1.0, 3.0, and 6.0 krad of gamma radiation and subsequently monitored regarding their developmental, feeding, and mating success. Also, sex ratios of adults treated as protonymphs were recorded as were sex ratios of embryos and F1 adults produced by these adults. Doses up to 1.0 krad did not prevent development of treated protonymphs to the adult stage or stop mating. Three krad reduced the number of treated protonymphs attaining adulthood and 6.0-krad treatment prevented all mites from developing to the adult stage. Egg (embryo) production was normal for mites treated with 0.50 krad, but significantly curtailed by doses of 0.75 krad and greater. Radiation doses used in this study did not appear to affect the normal variable sex ratios observed in untreated mites.

  17. Does famine influence sex ratio at birth? Evidence from the 1959–1961 Great Leap Forward Famine in China

    Science.gov (United States)

    Song, Shige

    2012-01-01

    The current study examined the long-term trend in sex ratio at birth between 1929 and 1982 using retrospective birth histories of 310 101 Chinese women collected in a large, nationally representative sample survey in 1982. The study identified an abrupt decline in sex ratio at birth between April 1960, over a year after the Great Leap Forward Famine began, and October 1963, approximately 2 years after the famine ended, followed by a compensatory rise between October 1963 and July 1965. These findings support the adaptive sex ratio adjustment hypothesis that mothers in good condition are more likely to give birth to sons, whereas mothers in poor condition are more likely to give birth to daughters. In addition, these findings help explain the lack of consistent evidence reported by earlier studies based on the 1944–1945 Dutch Hunger Winter or the 1942 Leningrad Siege. PMID:22456881

  18. Does famine influence sex ratio at birth? Evidence from the 1959-1961 Great Leap Forward Famine in China.

    Science.gov (United States)

    Song, Shige

    2012-07-22

    The current study examined the long-term trend in sex ratio at birth between 1929 and 1982 using retrospective birth histories of 310 101 Chinese women collected in a large, nationally representative sample survey in 1982. The study identified an abrupt decline in sex ratio at birth between April 1960, over a year after the Great Leap Forward Famine began, and October 1963, approximately 2 years after the famine ended, followed by a compensatory rise between October 1963 and July 1965. These findings support the adaptive sex ratio adjustment hypothesis that mothers in good condition are more likely to give birth to sons, whereas mothers in poor condition are more likely to give birth to daughters. In addition, these findings help explain the lack of consistent evidence reported by earlier studies based on the 1944-1945 Dutch Hunger Winter or the 1942 Leningrad Siege.

  19. Academic mothers have a pronounced seasonal variation in their offspring sex ratio.

    Science.gov (United States)

    Wallner, Bernard; Huber, Susanne; Mitterauer, Lukas; Pavlova, Borislava; Fieder, Martin

    2005-12-01

    Environmental and socio-demographic factors can influence the variation of the human sex ratio at birth (SRB = the ratio of males to males plus females). In particular, findings of seasonal, parental education, birth order, and maternal age effects on the SRB are not always in agreement, and a number of works report minimal variation. Here, we investigated the seasonality of SRB in academic and non-academic mothers employed at the University of Vienna, and who gave birth between 1963 and 2000 (n = 1932 births). All data were available from an anonymous employee database. Both groups, academic and non-academic mothers do not differ between their overall SRB. In academic mothers the SRB is significantly (P = 0.004) increased during the springtime and decreased during the summertime. Although in non-academic mothers the trend is comparable, it is far less pronounced and not significant (P = 0.345). When a multiple logistic model was applied to the data of academic mothers the only significant influencing factor on the SRB is the season, while birth order of children and mothers' age at childbirth has no effect. None of the three independent variables influence the SRB in non-academic mothers. These findings suggest a more flexible SRB rate in academic mothers than in non-academics within the seasons. We conclude that the significant seasonal variation of the SRB in academic women cannot be merely interpreted as an effect of socio-economic status but more likely as the interaction between socio-economic and environmental working conditions.

  20. Geographic clustering of the secondary sex ratio in Japan: association with demographic attributes.

    Science.gov (United States)

    Inoue, Yosuke; Umezaki, Masahiro; Watanabe, Chiho

    2013-03-01

    The secondary sex ratio (SSR) has been suggested to decrease with adverse physical and psychological environments. Previous studies have focused on reduced SSR under adverse conditions, such as war, terrorism attack and earthquake, but few studies have investigated fluctuations in SSR in moderately adverse environments. This study analysed municipality-level vital statistics records in Japan collected between 1998 and 2002 to identify high-SSR clusters and low-SSR clusters with spatial-scan statistics. In 999 runs of simulation, high- and low-SSR clusters were detected but fewer than 950 times, indicating that SSR was not geographically clustered in Japan if type I error of 5% was adopted. Explorative analyses comparing demographic attributes between high-SSR clusters and low-SSR clusters that were detected more than 500 times in 999 runs of simulation, showed that rate of spontaneous abortion, rate of artificial abortion and divorce rate were higher in low-SSR clusters, while male life expectancy, female life expectancy and total fertility rate were higher in a high-SSR cluster.

  1. A review of the established and suspected causes of variations in human sex ratio at birth.

    Science.gov (United States)

    James, William H; Grech, Victor

    2017-06-01

    The human sex ratio (proportion male) at birth (SRB) varies with many variables. Some of this variation has an established proximate cause. For instance, low SRB (more females) at birth are associated with various forms of stressful events or circumstances during or prior to pregnancy. These low SRB are almost certainly mainly caused by maternal-stress-induced male foetal loss. Other types of SRB variation are thought to be caused by hormonal variation in either or both parents around the time of conception. One or other of these two types of proximate cause seems to be responsible for most of the established variation of SRB. This will be illustrated here in respect of some selected forms of SRB variation. It seems likely that a clarification of the hormonal causes of SRB variation will also help explain the striking (apparent) inconsistencies in the results of reported tests of the influential Trivers-Willard hypothesis. It is further proposed that an appreciation of the evidence that parental hormones influence SRB may enhance understanding of several important pathologies (hepatitis B, toxoplasmosis, testicular cancer, prostate cancer and autism). Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Association of polyandry and sex-ratio drive prevalence in natural populations of Drosophila neotestacea.

    Science.gov (United States)

    Pinzone, Cheryl A; Dyer, Kelly A

    2013-10-22

    Selfish genetic elements bias their own transmission to the next generation, even at the expense of the fitness of their carrier. Sex-ratio (SR) meiotic drive occurs when an X-chromosome causes Y-bearing sperm to die during male spermatogenesis, so that it is passed on to all of the male's offspring, which are all daughters. How SR is maintained as a stable polymorphism in the absence of genetic suppressors of drive is unknown. Here, we investigate the potential for the female remating rate to affect SR dynamics in natural populations, using the fly Drosophila neotestacea. In controlled laboratory conditions, females from populations where SR is rare mate more often than females from populations where SR is common. Furthermore, only when males mate multiply does the average fertility of SR males relative to wild-type males decrease to a level that can prevent SR from spreading. Our results suggest that differences in the female mating rate among populations may contribute to SR dynamics in the wild, and thus also affect the outcome of this intragenomic conflict. In line with this, we also present evidence of a localized population crash due to SR that may have resulted from habitat fragmentation along with a reduced mating rate.

  3. Changes in Income at Macro Level Predict Sex Ratio at Birth in OECD Countries.

    Directory of Open Access Journals (Sweden)

    Ohto Kanninen

    Full Text Available 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.

  4. Flight patterns and sex ratio of beetles of the subfamily Dynastinae (Coleoptera, Melolonthidae

    Directory of Open Access Journals (Sweden)

    Larissa Simões Corrêa de Albuquerque

    2016-09-01

    Full Text Available ABSTRACT Dynastinae is one of the most representative subfamilies of Melolonthidae (Scarabaeoidea and has considerable ecological importance due mainly to interactions with plants of the families Araceae and Annonaceae. This relationship has led to the evolution of nocturnal activity patterns, which are influenced by environmental conditions. In the present study, abiotic factors were investigated to comprehend the influence on the flight patterns and identify the sex ratio of beetles from this subfamily. A study was conducted at Campo de Instrução Marechal Newton Cavalcanti in northeastern Brazil between December 2010 and November 2011. Thirteen species of Dynastinae were identified, most of which were from the genus Cyclocephala. Abundance and richness were greater in the dry season. Six species exhibited peak flight activity at specific periods of the night. More females than males were recorded for Cyclocephala distincta and C. paraguayensis. The present findings suggest that rainfall reduces the flight activity of these beetles and different time schedules may be related to mating behavior, foraging behavior and the avoidance of interspecific resource competition.

  5. Maternal Lineage of Warmblood Mares Contributes to Variation of Gestation Length and Bias of Foal Sex Ratio.

    Science.gov (United States)

    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 (pfoal (pfoals born alive at term, 48% were male and 52% female. Mare age group and maternal lineage significantly influenced the sex ratio of the foals (pfoal sex ratio in horses. In young primiparous and aged mares, the percentage of female offspring is higher than the expected 1:1 ratio.

  6. Genetic and morphological sex identification methods reveal a male-biased sex ratio in the Ivory Gull Pagophila eburnea

    OpenAIRE

    Yannic, Glenn; Broquet, Thomas; Strøm, Hallvard; Aebischer, Adrian; Dufresnes, Christophe; Maria V. Gavrilo; H. Grant Gilchrist; Mallory, Mark L.; Guy Morrison, R. I.; Sabard, Brigitte; Sermier, Roberto; Gilg, Olivier

    2016-01-01

    International audience; Sex identification of birds is relevant to studies of evolutionary biology and ecology and is often a central issue for the management and conservation of populations. The Ivory Gull Pagophila eburnea (Phipps, 1774) is a rare high-Arctic species whose main habitat is sea ice throughout the year. This species is currently listed Near Threatened by the IUCN, because populations have drastically declined in part of the species distribution in the recent past. Here we test...

  7. Effect of ejaculate, bull, and a double swim-up sperm processing method on sperm sex ratio.

    Science.gov (United States)

    Madrid-Bury, Ninoska; Fernández, Raúl; Jiménez, Adela; Pérez-Garnelo, Sonia; Moreira, Pedro Nuno; Pintado, Belén; de la Fuente, Julio; Gutiérrez-Adán, Alfonso

    2003-08-01

    Offspring gender preselection has applications of considerable economic, health and ecological interest. In this study we analysed modifications of the percentages of spermatozoa bearing Y and X chromosomes when semen samples are submitted to a double swim-up technique as a possible method for producing embryos of known sex with in vitro fertilisation protocols. As an initial experiment to provide accurate evaluation of the method we determined the possible incidence of natural deviations in the primary sex ratio between bulls or ejaculates, analysing the percentage of Y-chromosome DNA bearing spermatozoa (%Y-CDBS) with a polymerase chain reaction (PCR) amplification of X- and Y-specific fragments. Ejaculates were tested by direct semiquantitative PCR sexing and by sexing blastocysts produced in vitro with these spermatozoa. Bulls and ejaculates did not have any effect on the %Y-CDBS or on the sex ratio of embryos produced in vitro using these ejaculates. However, our double swim-up sperm preparation method produced differences in %Y-CDBS in some of the sperm fractions, suggesting that there are intrinsic differences in capacitation of X- and Y-bearing spermatozoa that might be used to produce embryos of the desired sex with in vitro fertilisation.

  8. Room model with three modal distributions of attached 220Rn progeny and dose conversion factor.

    Science.gov (United States)

    Nikezić, D; Stevanović, N

    2007-01-01

    Jacobi parametric room model was extended to the three modal distribution of aerosols, and applied to (220)Rn progeny. The computer program was developed to calculate ratios of progeny activity concentrations in different modes to (220)Rn concentration. The ratios are relatively small and they are given as functions on ventilation rate. Dose conversion factor (DCF) for (220)Rn progeny was calculated as 4.5 mSv WLM(-1), which is smaller by over three times than that for (222)Rn progeny.

  9. Operational sex ratio and density do not affect directional selection on male sexual ornaments and behavior.

    Science.gov (United States)

    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.

  10. CHANGES IN SEX RATIO AT BIRTH IN CHINA: A DECOMPOSITION BY BIRTH ORDER.

    Science.gov (United States)

    Jiang, Quanbao; Yu, Qun; Yang, Shucai; Sánchez-Barricarte, Jesús J

    2017-11-01

    The long-term high sex ratio at birth (SRB) is a serious issue in China. In this study, changes in SRB were decomposed into variations in SRB by birth order and compositional changes in female births by birth order. With SRB data from China's surveys and censuses, and SRB data from South Korea's vital registration and censuses from 1980-2015, the trend and decomposition results in SRB were compared between China and South Korea, and the decomposition results for urban and rural SRBs, and for provinces, are presented. In both China and South Korea the rise in the SRB was driven by a rise in the SRB at all birth orders, which was only partly counteracted by the change in the distribution of births by order. The overall rise in the SRB ended when there was a decline in the SRB at second birth or above in South Korea. In China the total effect of variations in SRB of all birth orders increased more for the rural population than for the urban population before 2000, resulting in a higher total SRB for rural than urban population. After 2000, the total effect of variations in SRB of all birth orders lowered the total SRB for the rural population, whereas the effect of compositional change increased the total SRB, leading to a very slight rise in the total SRB for the rural population. At the province level, there was no spatial autocorrelation for the changes in total SRB by province, the total effect of variations in SRB of all birth orders or the effect of compositional change. The effect of variations in SRB by birth order accounted for the majority of changes in total SRB in most provinces.

  11. Effects of age and sex ratios on offspring recruitment rates in translocated black rhinoceros.

    Science.gov (United States)

    Gedir, Jay V; Law, Peter R; du Preez, Pierre; Linklater, Wayne L

    2017-09-22

    Success of animal translocations depends on improving postrelease demographic rates toward establishment and subsequent growth of released populations. Short-term metrics for evaluating translocation success and its drivers, like postrelease survival and fecundity, are unlikely to represent longer-term outcomes. We used information theory to investigate 25 years of data on black rhinoceros (Diceros bicornis) translocations. We used the offspring recruitment rate (ORR) of translocated females-a metric integrating survival, fecundity, and offspring recruitment at sexual maturity-to detect determinants of success. Our unambiguously best model (AICω = 0.986) predicted that ORR increases with female age at release as a function of lower postrelease adult rhinoceros sex ratio (males:females). Delay of first postrelease reproduction and failure of some females to recruit any calves to sexual maturity most influenced the pattern of ORRs, and the leading causes of recruitment failure were postrelease female death (23% of all females) and failure to calve (24% of surviving females). We recommend translocating older females (≥6 years old) because they do not exhibit the reproductive delay and low ORRs of juveniles (<4 years old) or the higher rates of recruitment failure of juveniles and young adults (4-5.9 years old). Where translocation of juveniles is necessary, they should be released into female-biased populations, where they have higher ORRs. Our study offers the unique advantage of a long-term analysis across a large number of replicate populations-a science-by-management experiment as a proxy for a manipulative experiment, and a rare opportunity, particularly for a large, critically endangered taxon such as the black rhinoceros. Our findings differ from previous recommendations, reinforce the importance of long-term data sets and comprehensive metrics of translocation success, and suggest attention be shifted from ecological to social constraints on population

  12. Behavioral tactics of male sockeye salmon (Oncorhynchus nerka) under varying operating sex ratios

    Science.gov (United States)

    Quinn, Thomas P.; Adkison, Milo D.; Ward, Michael B.

    1996-01-01

    Previous studies have demonstrated several reproductive-behavior patterns in male salmon, including competitive and sneaking tactics, the formation of hierarchies, and non-hierarchical aggregations around ripe females. Through behavioral observations at varying spatial and temporal scales, we examined the hypothesis that operational sex ratio (OSR) determines male sockeye salmon (Oncorhynchus nerka) distribution and breeding tactics. Patterns of male distribution and behavior varied over both coarse and fine scales, associated with apparent shifts in reproductive opportunities, the physical characteristics of the breeding sites, and the deterioration of the fish as they approached death. Females spawned completely within a few days of arriving on the spawning grounds, whereas males courted the available ripe females from the date of their arrival on the spawning ground until their death. This difference in reproductive lifespans tended to elevate late-season OSRs but was partially counterbalanced by male departures and the arrival of other ripe females. The proportion of males able to dominate access to ripe females decreased and the number of large courting groups increased over the course of the season, apparently related to both increasing OSR and the deteriorating physical condition of males. However, great variation in OSR was observed within the spawning sites on a given day. OSRs were generally higher in shallow than in deep water, perhaps because larger females or more desirable breeding sites were concentrated in shallow water. The aggregations of males courting females were not stable (i.e. many arrivals and departures took place) and male aggression varied with group size. Aggression was most frequent at low OSRs and in groups of intermediate size (2–4 males per female), and much less frequent in larger groups, consistent with the needs of maximizing reproductive opportunities while minimizing unproductive energy expenditure. These results indicate

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

    Science.gov (United States)

    Marlowe, Frank W; Berbesque, J Colette

    2012-12-01

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

  14. Adult sex ratios and partner scarcity among hunter-gatherers: implications for dispersal patterns and the evolution of human sociality.

    Science.gov (United States)

    Kramer, Karen L; Schacht, Ryan; Bell, Adrian

    2017-09-19

    Small populations are susceptible to high genetic loads and random fluctuations in birth and death rates. While these selective forces can adversely affect their viability, small populations persist across taxa. Here, we investigate the resilience of small groups to demographic uncertainty, and specifically to fluctuations in adult sex ratio (ASR), partner availability and dispersal patterns. Using 25 years of demographic data for two Savannah Pumé groups of South American hunter-gatherers, we show that in small human populations: (i) ASRs fluctuate substantially from year to year, but do not consistently trend in a sex-biased direction; (ii) the primary driver of local variation in partner availability is stochasticity in the sex ratio at maturity; and (iii) dispersal outside of the group is an important behavioural means to mediate locally constrained mating options. To then simulate conditions under which dispersal outside of the local group may have evolved, we develop two mathematical models. Model results predict that if the ASR is biased, the globally rarer sex should disperse. The model's utility is then evaluated by applying our empirical data to this central prediction. The results are consistent with the observed hunter-gatherer pattern of variation in the sex that disperses. Together, these findings offer an alternative explanation to resource provisioning for the evolution of traits central to human sociality (e.g. flexible dispersal, bilocal post-marital residence and cooperation across local groups). We argue that in small populations, looking outside of one's local group is necessary to find a mate and that, motivated by ASR imbalance, the alliances formed to facilitate the movement of partners are an important foundation for the human-typical pattern of network formation across local groups.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal

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

    Science.gov (United States)

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

    2016-06-16

    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.

  16. The origin of a selfish B chromosome triggering paternal sex ratio in the parasitoid wasp Trichogramma kaykai

    NARCIS (Netherlands)

    Vugt, van J.J.F.A.; Jong, de J.H.S.G.M.; Stouthamer, R.

    2009-01-01

    This study uses molecular and cytogenetic methods to determine the origin of a B chromosome in some males of the wasp Trichogramma kaykai. This so-called paternal sex ratio (PSR) chromosome transmits only through sperm and shortly after fertilization triggers degeneration of the paternal genome,

  17. Mode of action, origin and structure of the Paternal Sex Ratio chromosome in the parasitoid wasp Trichogramma kaykai

    NARCIS (Netherlands)

    Vugt, van J.J.F.A.

    2005-01-01

    Selfish genetic elements are defined as genetic elements that have a replication advantage relative to the rest of the genome. They are ubiquitous in nature and were extensively reported for almost all species studied so far. A special type of selfish genetic element, the sex ratio distorter, is

  18. Phenotypic fitness effects of the selfish B chromosome, paternal sex ratio (PSR) in the parasitic wasp Nasonia vitripennis

    NARCIS (Netherlands)

    Beukeboom, Leo W.

    1994-01-01

    B chromosomes are often considered genomic parasites. Paternal sex ratio (PSR) is an extreme example of a parasitic B chromosome in the parasitoid wasp Nasonia vitripennis. PSR is transmitted through the sperm of carrier males and destroys the other paternal chromosomes in early fertilized eggs. PSR

  19. Status hierarchy, attractiveness hierarchy and sex ratio : Three contextual factors explaining the status-aggression link among adolescents

    NARCIS (Netherlands)

    Zwaan, Michiel; Dijkstra, Jan; Veenstra, René

    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

  20. Similar estimates of population genetic composition and sex ratio derived from carcasses and faeces of Eurasian otter Lutra lutra.

    Science.gov (United States)

    Dallas, John F; Coxon, Karen E; Sykes, Tim; Chanin, Paul R F; Marshall, Freda; Carss, David N; Bacon, Philip J; Piertney, Stuart B; Racey, Paul A

    2003-01-01

    Collecting faeces is viewed as a potentially efficient way to sample elusive animals. Nonetheless, any biases in estimates of population composition associated with such sampling remain uncharacterized. The goal of this study was to compare estimates of genetic composition and sex ratio derived from Eurasian otter Lutra lutra spraints (faeces) with estimates derived from carcasses. Twenty per cent of 426 wild-collected spraints from SW England yielded composite genotypes for 7-9 microsatellites and the SRY gene. The expected number of incorrect spraint genotypes was negligible, given the proportions of allele dropout and false allele detection estimated using paired blood and spraint samples of three captive otters. Fifty-two different spraint genotypes were detected and compared with genotypes of 70 otter carcasses from the same area. Carcass and spraint genotypes did not differ significantly in mean number of alleles, mean unbiased heterozygosity or sex ratio, although statistical power to detect all but large differences in sex ratio was low. The genetic compositions of carcass and spraint genotypes were very similar according to confidence intervals of theta and two methods for assigning composite genotypes to groups. A distinct group of approximately 11 carcass and spraint genotypes was detected using the latter methods. The results suggest that spraints can yield unbiased estimates of population genetic composition and sex ratio.

  1. Sex Ratio And Size At First Maturity Of Blue Swimming Crab (Portunus pelagicus Salemo Island Pangkep Regency

    Directory of Open Access Journals (Sweden)

    Muh. Saleh Nurdin

    2016-03-01

    Full Text Available Blue swimming crab (Portunuspelagicus is aeconomical valuable fisheries importantcommodity  due to the high demand and availability jobs created for the fishermen. Due to their high demand blue swimming crab heavily exploited from Salemo Island. This study aimed at comparing the sex ratio and the size at first maturity of blue swimming crab caught in mangrove ecosystems, coral reefs, and seagrass. Sex ratio was analyzed using chi square test and the size at first maturity was analyzed using the Spearman-Karber formula. The results showed the sex ratio ofmales and femalessmall crab caught in every ecosystem is balanced. The size at first maturity of blue swimming crab caught in mangrove, seagrass and coral reefs, each to the male 81,08 mm, 102,36 mm and 102,87 mm in width and size of female 94,54 mm, 83,35 mm, 98,31 mm width. In a reference to government regulations, the blue male swimming crab caught in the coral reef and seagrass ecosystems have yet to size at first maturity is allowed to be captured. Keywords: blue swimming crab, sex ratio,size at first maturity, Salemo Island

  2. Influence of postzygotic reproductive isolation on the interspecific transmission of the paternal sex ratio chromosome in Trichogramma

    NARCIS (Netherlands)

    Jeong, G.S.; Stouthamer, R.

    2006-01-01

    The paternal sex ratio (PSR) chromosome is a supernumerary chromosome that causes the destruction of the paternal chromosome set in the first mitosis in a fertilized egg. It is known from parasitoid wasps in the genera Nasonia and Trichogramma (Hymenoptera). In these haplodiploids, the egg

  3. A Radon Progeny Deposition Model

    Science.gov (United States)

    Guiseppe, V. E.; Elliott, S. R.; Hime, A.; Rielage, K.; Westerdale, S.

    2011-04-01

    The next generation low-background detectors operating underground aim for unprecedented low levels of radioactive backgrounds. Although the radioactive decays of airborne radon (particularly 222Rn) and its subsequent progeny present in an experiment are potential backgrounds, also problematic is the deposition of radon progeny on detector materials. Exposure to radon at any stage of assembly of an experiment can result in surface contamination by progeny supported by the long half life (22 y) of 210Pb on sensitive locations of a detector. An understanding of the potential surface contamination from deposition will enable requirements of radon-reduced air and clean room environments for the assembly of low background experiments. It is known that there are a number of environmental factors that govern the deposition of progeny onto surfaces. However, existing models have not explored the impact of some environmental factors important for low background experiments. A test stand has been constructed to deposit radon progeny on various surfaces under a controlled environment in order to develop a deposition model. Results from this test stand and the resulting deposition model are presented.

  4. Prenatal stress, gestational age and secondary sex ratio: the sex-specific effects of exposure to a natural disaster in early pregnancy.

    Science.gov (United States)

    Torche, Florencia; Kleinhaus, Karine

    2012-02-01

    Previous research suggests that maternal exposure to acute stress has a negative impact on the duration of pregnancy, and that this effect may vary by the time of exposure. It has also been proposed that stress exposure reduces the ratio of male-to-female births. To date, no study has jointly examined both outcomes, although they may be strongly related. Using population-level data with no selectivity, we jointly study the sex-specific effect of stress on the duration of pregnancy and the observed sex ratio among pregnant women exposed to a major earthquake in Chile. In a quasi-experimental design, women exposed to the earthquake in different months of gestation were compared with women pregnant 1 year earlier. Estimates from a comparison group of pregnant women living in areas not affected by the earthquake were also examined to rule out confounding trends. Regression models were used to measure the impact of earthquake exposure on gestational age and preterm birth by sex across month of gestation. A counterfactual simulation was implemented to assess the effect of the earthquake on the secondary sex ratio accounting for the differential impact of stress on gestational age by sex. Earthquake exposure in Months 2 and 3 of gestation resulted in a significant decline in gestational age and increase in preterm delivery. Effects varied by sex, and were much larger for female than male pregnancies. Among females, the probability of preterm birth increased by 0.038 [95% confidence interval (CI): 0.005, 0.072] in Month 2 and by 0.039 (95% CI: 0.002, 0.075) in Month 3. Comparable increases for males were insignificant at the conventional P age, a decline in the male-to-female ratio in Month 3 of exposure was detected [-0.058 (95% CI: -0.113, -0.003)]. Maternal exposure to an exogenous stressor early but not late in the pregnancy affects gestational age and the probability of preterm birth. This effect is much stronger in females than males. Stress exposure in early

  5. The evolution of sex ratio distorter suppression affects a 25 cM genomic region in the butterfly Hypolimnas bolina.

    Directory of Open Access Journals (Sweden)

    Emily A Hornett

    2014-12-01

    Full Text Available Symbionts that distort their host's sex ratio by favouring the production and survival of females are common in arthropods. Their presence produces intense Fisherian selection to return the sex ratio to parity, typified by the rapid spread of host 'suppressor' loci that restore male survival/development. In this study, we investigated the genomic impact of a selective event of this kind in the butterfly Hypolimnas bolina. Through linkage mapping, we first identified a genomic region that was necessary for males to survive Wolbachia-induced male-killing. We then investigated the genomic impact of the rapid spread of suppression, which converted the Samoan population of this butterfly from a 100:1 female-biased sex ratio in 2001 to a 1:1 sex ratio by 2006. Models of this process revealed the potential for a chromosome-wide effect. To measure the impact of this episode of selection directly, the pattern of genetic variation before and after the spread of suppression was compared. Changes in allele frequencies were observed over a 25 cM region surrounding the suppressor locus, with a reduction in overall diversity observed at loci that co-segregate with the suppressor. These changes exceeded those expected from drift and occurred alongside the generation of linkage disequilibrium. The presence of novel allelic variants in 2006 suggests that the suppressor was likely to have been introduced via immigration rather than through de novo mutation. In addition, further sampling in 2010 indicated that many of the introduced variants were lost or had declined in frequency since 2006. We hypothesize that this loss may have resulted from a period of purifying selection, removing deleterious material that introgressed during the initial sweep. Our observations of the impact of suppression of sex ratio distorting activity reveal a very wide genomic imprint, reflecting its status as one of the strongest selective forces in nature.

  6. The evolution of sex ratio distorter suppression affects a 25 cM genomic region in the butterfly Hypolimnas bolina.

    Science.gov (United States)

    Hornett, Emily A; Moran, Bruce; Reynolds, Louise A; Charlat, Sylvain; Tazzyman, Samuel; Wedell, Nina; Jiggins, Chris D; Hurst, Greg D D

    2014-12-01

    Symbionts that distort their host's sex ratio by favouring the production and survival of females are common in arthropods. Their presence produces intense Fisherian selection to return the sex ratio to parity, typified by the rapid spread of host 'suppressor' loci that restore male survival/development. In this study, we investigated the genomic impact of a selective event of this kind in the butterfly Hypolimnas bolina. Through linkage mapping, we first identified a genomic region that was necessary for males to survive Wolbachia-induced male-killing. We then investigated the genomic impact of the rapid spread of suppression, which converted the Samoan population of this butterfly from a 100:1 female-biased sex ratio in 2001 to a 1:1 sex ratio by 2006. Models of this process revealed the potential for a chromosome-wide effect. To measure the impact of this episode of selection directly, the pattern of genetic variation before and after the spread of suppression was compared. Changes in allele frequencies were observed over a 25 cM region surrounding the suppressor locus, with a reduction in overall diversity observed at loci that co-segregate with the suppressor. These changes exceeded those expected from drift and occurred alongside the generation of linkage disequilibrium. The presence of novel allelic variants in 2006 suggests that the suppressor was likely to have been introduced via immigration rather than through de novo mutation. In addition, further sampling in 2010 indicated that many of the introduced variants were lost or had declined in frequency since 2006. We hypothesize that this loss may have resulted from a period of purifying selection, removing deleterious material that introgressed during the initial sweep. Our observations of the impact of suppression of sex ratio distorting activity reveal a very wide genomic imprint, reflecting its status as one of the strongest selective forces in nature.

  7. Maternal Lineage of Warmblood Mares Contributes to Variation of Gestation Length and Bias of Foal Sex Ratio.

    Directory of Open Access Journals (Sweden)

    J Kuhl

    Full Text Available 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.

  8. Evolution of sexual size dimorphism and its relationship with sex ratio in carabid beetles of Genus Ceroglossus Solier

    Directory of Open Access Journals (Sweden)

    Hugo A. BENÍTEZ, Jorge AVARIA-LLAUTUREO, Cristian B. CANALES-AGUIRRE, Viviane JEREZ, Luis E. PARRA, Cristián E. HERNÁNDEZ

    2013-12-01

    Full Text Available Although the degree of mate competition, given extreme differences in sex ratio, explains much of the pattern of male-biased size dimorphism among diverse taxa, it fails for some species which have potential for intense male competition for mates and yet exhibit little or no sexual size dimorphism (SSD. This fact suggest that species with low SSD should be express the effect of evolutionary pressure in non-obvious geometrical shape promoted by sex ratio in an evolutionary time scale. To evaluate this hypothesis we used phylogenetic comparative method in a Bayesian framework to investigate the evolution of SSD and the role of sex ratio at inter-specific level in the species of Ceroglossus (Coleoptera: Carabidae. In our results the proportion farthest from 1:1 is associated with more disparate body shape, even though the entire group has minimum variation in sex ratio, which is an intrinsic life history character of this group considering its phylogenetic conservatism or phylogenetic signal. We suggest that the sex ratio has determined the dimorphism degree during evolution of this group, since both traits have increased or decreased together during the species divergence (i.e. positive phylogenetic correlation: r2≈0.85. We suggest that morphological studies of SSD will benefit from using comparative method with Bayesian approaches to assess the effect of phylogenetic history and its uncertainty. Finally, this will be allow to researchers to quantify the uncertainty of specific evolutionary hypotheses accounting for observed sexual dimorphism patterns [Current Zoology 59 (6: 769–777, 2013].

  9. Globally Declining Population of Women Folk Causing Sex Imbalance Is a Serious Concern: An Analysis of Sex Ratio around the Globe

    Directory of Open Access Journals (Sweden)

    Rajesh K. Gautam

    2015-01-01

    Full Text Available Successful existence and perpetuation of any species depend on its reproductive success. In case of humans, the theoretical proportion of males and females should be 1 : 1, but this equilibrium was disturbed in many parts of the world. What are the determinants of sex imbalance in human should be found out to combat the problem. The data were gathered for 227 countries. The sex ratio for human population of the world was found 101 males for 100 females, but it varies from 74 to 219 among the countries. The number of countries having higher number of females as compared to males is 132, as they have 99 or less males per 100 females, whereas in 71 countries the total population of males is greater than the females. And only 24 countries have balanced sex ratio. Regression analysis shows that fertility, rate of natural increase, mortality, and gender inequality index have inverse effect, and they account for 24.4%, 23.1%, 18.8%, 18.9%, 16.3%, 16.1%, and 5.1% of variability, respectively. There is great need to identify such countries and region where sex selective abortion is being practiced and to find out appropriate strategies to combat such problem.

  10. Marriage season, promptness of successful pregnancy and first-born sex ratio in a historical natural fertility population - evidence for sex-dependent early pregnancy loss?

    Science.gov (United States)

    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.

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

    OpenAIRE

    Madhukar Shivajirao Dama

    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 c...

  12. Divorce, Abortion and Children's Sex Ratio: The Impact of Divorce Reform in China

    OpenAIRE

    Sun, Ang; Zhao, Yaohui

    2014-01-01

    This paper explores how the relative circumstances of men and women following marital dissolution affect sex-selection behavior within marriages. China's 2001 divorce reform liberalized divorce in favor of women and secured women's property rights after separation. We use this improvement in women's bargaining power in marriage for a regression discontinuity analysis of the demand for sex-selective abortions. We show that the increase in women's bargaining power reduces the propensity to have...

  13. Mapping Causes and Implications of India’s Skewed Sex Ratio and Poverty problem using Fuzzy & Neutrosophic Relational Maps

    Directory of Open Access Journals (Sweden)

    Gaurav

    2016-08-01

    Full Text Available Numerous studies by different researchers have confirmed that skewed sex ratio is a critical social problem in India. This enduring problem of gender imbalance is the collective result of factors like sex selective abortion, gender discrimination, son preference for the preservation of tribe, emergence of new technologies in medical field and many more factors. Another severe problem to be addressed in India is poverty. Many factors contribute to the perpetuation of poverty such as illiteracy, bad governance, under employment and various other reasons. Despite of India's accelerated growth rate, poverty in India is still prevalent.

  14. Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio)

    Science.gov (United States)

    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.

  15. Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio).

    Science.gov (United States)

    Sharma, Prakash; Patiño, Reynaldo

    2013-04-01

    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. Published by Elsevier Inc.

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

    Directory of Open Access Journals (Sweden)

    Adrian Łukowski

    Full Text Available 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.

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Change in Body Mass Can Overrule the Effects of Maternal Testosterone on Primary Offspring Sex Ratio of First Eggs in Homing Pigeons

    NARCIS (Netherlands)

    Goerlich, V. C.; Dijkstra, C.; Boonekamp, J. J.; Groothuis, T. G. G.

    2010-01-01

    The phenomenon of primary offspring sex ratio adjustment is being extensively studied, yet knowledge of the underlying proximate mechanism is still mainly hypothetical. Female birds are the heterogametic sex, thus potentially controlling the sex of the gamete to be fertilized. In several bird

  19. Effect of male body mass index on live-birth sex ratio of singletons after assisted reproduction technology.

    Science.gov (United States)

    Zhu, Jinliang; Tang, Wenhao; Mao, Jiaming; Li, Junsheng; Zhuang, Xinjie; Liu, Ping; Qiao, Jie

    2015-12-01

    To determine the effect of male body mass index (BMI) on the probability of achieving a live birth and the sex ratio of singletons at birth after IVF and intracytoplasmic sperm injection (ICSI) treatment. A retrospective cohort study. University-affiliated infertility center. Patients seeking infertility treatment who received IVF or ICSI treatment with autologous oocytes from January 2009 to December 2013. None. Live-birth sex ratio of singletons at birth stratified by male BMI and adjusted by parental age, parental BMI, type of infertility, parity, embryo culture media, and cause of infertility. A total of 8,490 couples undergoing IVF or ICSI treatment resulted in 39.12% live births and gave birth to 2,377 live birth singletons and 943 twins. There was no significant difference in the live birth rate between groups stratified by BMI. The probability of live births for overweight and obese groups were not decreased compared with the normal-weight group; similar null findings existed in the IVF and ICSI subgroups. Of note, the sex ratio of offspring in the overweight and obese male groups was significantly higher than in the normal-weight group (1.27 vs. 1.07). Male BMI was significantly associated with sex ratio of singletons after adjusting for confounders. In twins, incidences of twins with male-male infants in the overweight/obese group were not different from the normal-weight group. Increased male BMI has no effect on live birth success, but has an increased probability of giving birth to male singletons. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  20. The effects of sex-ratio and density on locomotor activity in the house fly, Musca domestica

    DEFF Research Database (Denmark)

    Bahrndorff, Simon; Kjaersgaard, Anders; Pertoldi, Cino

    2012-01-01

    Although locomotor activity is involved in almost all behavioral traits, there is a lack of knowledge on what factors affect it. This study examined the effects of sex-ratio and density on the circadian rhythm of locomotor activity of adult Musca domestica L. (Diptera: Muscidae) using an infra-re...... of the behavioral interactions between houseflies and highlight the importance of these factors when designing behavioral experiments using M. domestica....

  1. Germ-line origins of mutation in families with hemophilia B: The sex ratio varies with the type of mutation

    Energy Technology Data Exchange (ETDEWEB)

    Ketterling, R.P.; Vielhaber, E.; Bottema, C.D.K.; Schaid, D.J.; Sommer, S.S. (Mayo Clinic/Foundation, Rochester, MN (United States)); Cohen, M.P. (Vanderbilt Univ., Nashville, TN (United States)); Sexauer, C.L. (Children' s Hospital, Oklahoma City, OK (United States))

    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.

  2. High sex ratios in rural China: declining well-being with age in never-married men

    Science.gov (United States)

    Zhou, Xudong

    2017-01-01

    In parts of rural China male-biased sex ratios at birth, combined with out-migration of women, have led to highly male-biased adult sex ratios, resulting in large numbers of men being unable to marry, in a culture where marriage and reproduction are an expectation. The aim of this study was to test the hypotheses that older unmarried men are more predisposed to depression, low self-esteem and aggression than both those who are married, and those who are younger and unmarried. Self-completion questionnaires were administered among men aged 20–40 in 48 villages in rural Guizhou province, southwestern China. Tools used included the Beck Depression Inventory, the Rosenberg's Self-esteem Scale and the Bryant-Smith Aggression Questionnaire. Regression models assessed psychological wellbeing while adjusting for socio-demographic variables. Completed questionnaires were obtained from 957 never-married men, 535 married men aged 30–40, 394 partnered men and 382 unpartnered men aged 20–29. After adjusting for socio-demographic variables, never-married men were more predisposed to depression (p low self-esteem (p < 0.05) and suicidal tendencies (p < 0.001). All the psychological measures deteriorated with age in never-married men. In contrast, married men remained stable on these dimensions with age. Never-married men are a psychologically highly vulnerable group in a society where marriage is an expectation. Since the highest birth sex–ratio cohorts have not yet reached reproductive age, the social tragedy of these men will last for at least another generation. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’. PMID:28760765

  3. Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity

    NARCIS (Netherlands)

    Fawcett, Tim W.; Kuijper, Bram; Weissing, Franz J.; Pen, Ido

    2011-01-01

    Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because

  4. Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio

    Science.gov (United States)

    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 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.

  5. Sheep grazing causes shift in sex ratio and cohort structure of Brandt's vole: Implication of their adaptation to food shortage.

    Science.gov (United States)

    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. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  6. Sex ratio estimations of loggerhead marine turtle hatchlings by incubation duration and nest temperature at Sirte beaches (Libya

    Directory of Open Access Journals (Sweden)

    Imed Jribi

    2013-10-01

    Full Text Available Hatchling sex ratios in loggerhead marine turtles (Caretta caretta were estimated on the beaches near Sirte (Libya, using two methods: incubation duration and nest mean temperature during the middle third of the incubation period. Electronic temperature/humidity loggers were deployed at a total of 13 selected nests at Al-Ghbeba, Al-Thalateen, west of Al- Thalateen, Shash and Al-Arbaeen. The incubation period ranged from 47 to 58 days and average temperature ranged from 29°C to 31.8°C. The maximum temperature during this period increased to between 0.6°C and 3.5°C, while the mean temperature also increased during the middle third of the incubation period compared with the first third and continued to increase during the last third. As expected, this study showed that the temperature in the nest decreased with increasing depth of the nest. The results showed a female-dominated sex ratio at 85.4% on the basis of incubation duration and 70.4% on the basis of mean temperature. These findings support the reported highly female-skewed sex ratios in the Mediterranean and elsewhere.

  7. Missing girls in India: infanticide, feticide and made-to-order pregnancies? Insights from hospital-based sex-ratio-at-birth over the last century.

    Science.gov (United States)

    Sahni, Mohit; Verma, Neeraj; Narula, D; Varghese, Raji Mathew; Sreenivas, V; Puliyel, Jacob M

    2008-05-21

    There are 44 million missing women in India. Gender bias; neglect of girls, infanticides and feticides are responsible. The sex ratio at birth can be used to examine the influence of antenatal sex selection on the sex ratio. Records from 321,991 deliveries at one hospital over 11 decades were utilized. The middle year in each decade was taken as representative of the decade. Data from 33,524 deliveries were then analyzed. Data for each decade was combined with that of previous decades and compared to the data of subsequent decades to look for any change in the trend. Sex ratio in the second children against sex of the first child was studied separately. The mean sex ratio for the 110 years examined was 910 girls to 1000 boys (95% CI; 891 to 930). The sex ratio dropped significantly from 935 (CI: 905 to 967) before 1979, to 892 (CI: 868 to 918) after 1980 (P = 0.04). The sex ratio in the second child was significantly lower if the first child was a girl [716 (CI: 672 to 762] (Pratio fell significantly after 1980 when ultra sound machines for antenatal sex determination became available. The sex ratio in second children if the first was a girl was even lower. Sex selective abortions after antenatal sex determination are thus implicated. However data on second children especially the excess of girls born to mothers who have a previous boy seen in the decade before the advent of antenatal ultra sound machines, suggests that other means of sex selection are also used.

  8. The contribution of dream masochism to the sex ratio difference in major depression.

    Science.gov (United States)

    Cartwright, R D; Wood, E

    1993-02-01

    Twenty-five women and twenty-one men undergoing divorce had three laboratory nights of sleep on two occasions 1 year apart. On the third night, dream reports were elicited from subjects for each period of rapid eye movement (REM) sleep. Three groups differing on dream "masochism" were compared on personality, sex role, and social adjustment. Women "masochistic" dreamers had significantly higher scores on a scale of negative aspects of traditional feminine sex role identity than men or women without such dreams. They also showed less improvement at followup and had more need for emotional support. Dream masochism may be a continuing cognitive characteristic that contributes to the vulnerability of women to major depression.

  9. Mating behaviour of the orange mud crab, Scylla olivacea: The effect of sex ratio and stocking density on mating success

    Directory of Open Access Journals (Sweden)

    Khor Waiho

    2015-11-01

    Full Text Available Mud crabs from the genus Scylla have high commercial value and are considered as one of the highly sought luxury seafood items. Thorough understanding about their biology and mating behaviour is vital in providing important information for a sustainable exploitation and future incorporation into the aquaculture industry. The mating process of S. olivacea lasted 82.0 ± 10.8 h was divided into four phases: precopulation, molting, copulation, and postcopulation. Courtship displays and fighting were shown by mature males while they were courting females. Precopulatory position lasted for 55.2 ± 10.8 h before the pairs disengaged for the female to molt. The molting process was 4.6 ± 0.3 h. Copulation (mean duration was 6.6 ± 0.5 h occurred while the female’s exoskeleton was still soft. Postcopulatory guarding lasted for 13.6 ± 0.6 h. Separation of the mating pairs indicates the end of postcopulation phase. Mating success percentage was unaffected by sex ratio, but inversely affected by stocking density. Cumulative mortality increased with increasing stocking density and unequal sex ratios. Postcopulatory guarding duration was significantly shorter in treatment with 1 male:2 females ratio and treatment with the lowest stocking density (2 crabs m−2. We proposed rearing of mud crab broodstocks for mating purpose using sex ratio of 1 male:2 females and stocking density of 6 crabs m−2 to maximize output (successful mating pairs while maintaining low mortality percentage and shorter postcopulatory guarding duration.

  10. Highly skewed sex ratios and biased fossil deposition of moa: ancient DNA provides new insight on New Zealand's extinct megafauna

    Science.gov (United States)

    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.

  11. Sex determination: genetic models for oysters.

    Science.gov (United States)

    Hedrick, Philip W; Hedgecock, Dennis

    2010-01-01

    In oysters, sex is determined partly by environment, but previous studies employing controlled crosses suggest that genetic factors are also important. Sex ratios in both full- and half-sib families of the Pacific oyster show paternal control of sex ratio and suggest that a single major gene with 2 genotypes controls sex in the Pacific oyster, with FM oysters being male and FF oysters maturing as male or female. Here, we show that such a model does indeed produce a stable polymorphism for either single or multiple age-class populations, though under limited ranges of f, the probability that an FF individual matures as a female. However, this 2-genotype model cannot explain observed heterogeneity of sex ratios among progeny from different dams within half-sib families. We propose an alternative 3-genotype model that also produces a stable polymorphism, for either single or multiple age-class populations, but over all values of f between zero and one. This model accounts for sex ratio heterogeneity among male half-sib families because it features 2 types of females, a protandric FM and a fixed female FF. Furthermore, the 3-genotype model, accounts for the frequencies of mating types inferred from the observed sex ratios of families more closely than the 2-genotype model. Although the mechanism of sex determination may ultimately prove more complex, simple genetic mechanisms can account for the broad features of sexual maturation in oyster families and the stability of sex ratios in populations.

  12. Old Habits Die Hard? Lingering Son Preference in an Era of Normalizing Sex Ratios at Birth in South Korea.

    Science.gov (United States)

    Yoo, Sam Hyun; Hayford, Sarah R; Agadjanian, Victor

    2017-01-01

    South Korea was among the first countries to report both an abnormally high sex ratio at birth (SRB) and its subsequent normalization. We examine the role of son preference in driving fertility intentions during a period of declining SRB and consider the contribution of individual characteristics and broader social context to explaining changes in intentions. We employ data from the National Survey on Fertility, Family Health and Welfare that span 1991-2012. We find that reported son preference declined to a great extent but remained substantial by the end of the observation period, and that the intention to have a third child still differed by sex of existing children. Change in individual-level factors does not explain the decline in son preference, suggesting that broad social changes were also important. This study provides a better understanding of how son preference evolves in the post-transitional context of very low fertility.

  13. Neutropenia and neutrophil-to-lymphocyte ratio in a healthy Korean population: race and sex should be considered.

    Science.gov (United States)

    Kweon, O J; Lee, M-K; Kim, H-J; Chung, J-W; Choi, S-H; Kim, H R

    2016-06-01

    We evaluated the prevalence and severity of asymptomatic neutropenia in a healthy Korean population according to sex and age. We explored normal neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in an asymptomatic Korean population and the association of these ratios with biomarkers related to inflammation, rheumatoid disease, and glucose metabolism. We analyzed complete blood cell counts in 83 740 subjects who participated in a routine health check-up program. NLR and PLR were compared to age, rheumatoid factor, C-reactive protein (CRP), erythrocyte sedimentation rate, hemoglobin A1c, and fasting glucose levels. Of the entire study population, 7.48% exhibited neutropenia; 8.61% of females and 6.69% of males. The neutropenia was more severe in females compared to males (P neutropenia should be re-established according to sex and race. NLR and PLR cutoff values for disease evaluation should be established separately according to race and age. © 2016 John Wiley & Sons Ltd.

  14. Second to fourth digit ratio (2D:4D and concentrations of circulating sex hormones in adulthood

    Directory of Open Access Journals (Sweden)

    Morris Howard A

    2011-04-01

    Full Text Available Abstract Background The second to fourth digit ratio (2D:4D is used as a marker of prenatal sex hormone exposure. The objective of this study was to examine whether circulating concentrations of sex hormones and SHBG measured in adulthood was associated with 2D:4D. Methods This analysis was based on a random sample from the Melbourne Collaborative Cohort Study. The sample consisted of of 1036 men and 620 post-menopausal women aged between 39 and 70 at the time of blood draw. Concentrations of circulating sex hormones were measured from plasma collected at baseline (1990-1994, while digit length was measured from hand photocopies taken during a recent follow-up (2003-2009. The outcome measures were circulating concentrations of testosterone, oestradiol, dehydroepiandrosterone sulphate, androstenedione, Sex Hormone Binding Globulin, androstenediol glucoronide for men only and oestrone sulphate for women only. Free testosterone and oestradiol were estimated using standard formulae derived empirically. Predicted geometric mean hormone concentrations (for tertiles of 2D:4D and conditional correlation coefficients (for continuous 2D:4D were obtained using mixed effects linear regression models. Results No strong associations were observed between 2D:4D measures and circulating concentrations of hormones for men or women. For males, right 2D:4D was weakly inversely associated with circulating testosterone (predicted geometric mean testosterone was 15.9 and 15.0 nmol/L for the lowest and highest tertiles of male right 2D:4D respectively (P-trend = 0.04. There was a similar weak association between male right 2D:4D and the ratio of testosterone to oestradiol. These associations were not evident in analyses of continuous 2D:4D. Conclusions There were no strong associations between any adult circulating concentration of sex hormone or SHGB and 2D:4D. These results contribute to the growing body of evidence indicating that 2D:4D is unrelated to adult sex

  15. Exposure to persistent organic pollutants and sperm sex chromosome ratio in men from the Faroe Islands

    DEFF Research Database (Denmark)

    Kvist, L; Giwercman, A; Weihe, P

    2014-01-01

    People in the Arctic as well as fishermen on the polluted Swedish east coast are highly exposed to persistent organic pollutants (POPs). These compounds have been shown to affect the sperm Y:X chromosome ratio. In present study, the aim was to investigate whether polychlorinated biphenyl (PCB...

  16. Temperature and its variations in birth rates and sex ratio in Greater ...

    African Journals Online (AJOL)

    That is, rates of conceptions among women generally, increase during relatively low temperature periods and vice versa. While female birth rates are negatively related with temperature, the reverse is the case with male births. This implies that the ratio of female birth decreases with increasing temperature whereas male ...

  17. Sex-specific relationship between digit ratio (2D : 4D) and romantic jealousy

    NARCIS (Netherlands)

    Park, Justin H.; Wieling, Martijn B.; Buunk, Abraham P.; Massar, Karlijn

    The ratio of index finger length to ring finger length (2D:D4) is an index of prenatal androgen exposure. In a study with 71 female and 52 male undergraduate students, we assessed the relationship between 2D:D4 and jealousy with respect to various dimensions of rival characteristics. Following the

  18. Effects of a sex-ratio distorting endosymbiont on mtDNA variation in a global insect pest

    Directory of Open Access Journals (Sweden)

    Cook James M

    2009-03-01

    Full Text Available Abstract 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

  19. An X-linked sex ratio distorter in Drosophila simulans that kills or incapacitates both noncarrier sperm and sons.

    Science.gov (United States)

    Rice, William R

    2014-07-31

    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. Copyright © 2014 Rice.

  20. Association of UV radiation with multiple sclerosis prevalence and sex ratio in France.

    Science.gov (United States)

    Orton, S-M; Wald, L; Confavreux, C; Vukusic, S; Krohn, J P; Ramagopalan, S V; Herrera, B M; Sadovnick, A D; Ebers, G C

    2011-02-01

    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. 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. 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). 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.

  1. Spousal Bargaining Over Care for Elderly Parents in China: Imbalances in Sex Ratios Influence the Allocation of Support.

    Science.gov (United States)

    Porter, Maria

    2017-01-01

    Using a unique Chinese survey of parents and adult children, this paper examines how married children negotiate with their spouses for time devoted to caring for their own parents. Applying a collective bargaining framework, I show that the sex ratio at marriage shifts household bargaining in favour of the husband's parents when women are less scarce, or against his parents when women are scarcer. Such changing dynamics in the family may potentially reverse the current preference for sons in China, implying that those with sons, rather than daughters, may be increasingly in need of state support.

  2. Does landscape fragmentation influence sex ratio of dioecious plants? A case study of Pistacia chinensis in the Thousand-Island Lake region of China.

    Directory of Open Access Journals (Sweden)

    Lin Yu

    Full Text Available The Thousand-Island Lake region in Zhejiang Province, China is a highly fragmented landscape with a clear point-in-time of fragmentation as a result of flooding to form the reservoir. Islands in the artificial lake were surveyed to examine how population sex ratio of a dioecious plant specie Pistacia chinensis B. was affected by landscape fragmentation. A natural population on the mainland near the lake was also surveyed for comparison. Population size, sex ratio and diameter at breast height (DBH of individuals were measured over 2 years. More than 1,500 individuals, distributed in 31 populations, were studied. Soil nitrogen in the different populations was measured to identify the relationship between sex ratio and micro-environmental conditions. In accordance with the results of many other reports on biased sex ratio in relation to environmental gradient, we found that poor soil nitrogen areas fostered male-biased populations. In addition, the degree of sex ratio bias increased with decreasing population size and population connectivity. The biased sex ratios were only found in younger individuals (less than 50 years old in small populations, while a stable 1∶1 sex ratio was found in the large population on the mainland. We concluded that the effects of landscape fragmentation on the dioecious population sex ratio were mainly achieved in relation to changing soil nitrogen conditions in patches and pollen limitation within and among populations. Large populations could maintain a more suitable environment in terms of nutrient conditions and pollen flow, subsequently maintaining a stable sex ratio in dioecious plant populations. Both micro-environmental factors and spatial structure should be considered in fragmented landscape for the conservation of dioecious plant species.

  3. Does landscape fragmentation influence sex ratio of dioecious plants? A case study of Pistacia chinensis in the Thousand-Island Lake region of China.

    Science.gov (United States)

    Yu, Lin; Lu, Jianbo

    2011-01-01

    The Thousand-Island Lake region in Zhejiang Province, China is a highly fragmented landscape with a clear point-in-time of fragmentation as a result of flooding to form the reservoir. Islands in the artificial lake were surveyed to examine how population sex ratio of a dioecious plant specie Pistacia chinensis B. was affected by landscape fragmentation. A natural population on the mainland near the lake was also surveyed for comparison. Population size, sex ratio and diameter at breast height (DBH) of individuals were measured over 2 years. More than 1,500 individuals, distributed in 31 populations, were studied. Soil nitrogen in the different populations was measured to identify the relationship between sex ratio and micro-environmental conditions. In accordance with the results of many other reports on biased sex ratio in relation to environmental gradient, we found that poor soil nitrogen areas fostered male-biased populations. In addition, the degree of sex ratio bias increased with decreasing population size and population connectivity. The biased sex ratios were only found in younger individuals (less than 50 years old) in small populations, while a stable 1∶1 sex ratio was found in the large population on the mainland. We concluded that the effects of landscape fragmentation on the dioecious population sex ratio were mainly achieved in relation to changing soil nitrogen conditions in patches and pollen limitation within and among populations. Large populations could maintain a more suitable environment in terms of nutrient conditions and pollen flow, subsequently maintaining a stable sex ratio in dioecious plant populations. Both micro-environmental factors and spatial structure should be considered in fragmented landscape for the conservation of dioecious plant species.

  4. The daughter deficit — Exploring declining sex ratios in India | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-02-21

    Feb 21, 2011 ... In a “normal world,” the female population equals or slightly surpasses the number of males. Except in India, that is, where the situation is just the opposite, where the gender ratio — or the number of females to males — is known to be among the most imbalanced in the world. Although China has the most ...

  5. Effect of estradiol-17β on the sex ratio, growth and survival of juvenile common snook (Centropomus undecimalis

    Directory of Open Access Journals (Sweden)

    Cristina Vaz Avelar de Carvalho

    2014-07-01

    Full Text Available Sex control in fish is a promising technique for aquaculture, since it gives advantages associated with one sex. The aim of this study was to investigate the feminization of common snook (Centropomus undecimalis by oral administration of two doses of estradiol-17β (50 and 100 mg E2 kg-1 feed and control treatment for 45 days and to evaluate their effects on the sex ratio, growth and survival of common snook juveniles. After this period, fish were fed only with commercial feed without hormone supplementation. During the period of E2 administration, the control fish grew more than those in the other treatments. At the end of the experiment in the treatment with 50 mg E2 kg-1, 26.32% of the fish were male, 68.42% were female, and 5.26% were intersex. In the treatment with 100 mg E2 kg-1, 10% of the fish were male, and 90% were female. There was no difference in growth among the treatments after 11 months. This study showed that it is possible to obtain 90% common snook females using feeds with 100 mg E2 kg-1 for 45 days without impairing the fish growth or survival.

  6. Sex ratio and size structure of Micropogonias furnieri (Desmarest, 1823 (Perciformes, Sciaenidae in Sepetiba Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    R. N. Vicentini

    Full Text Available Sex ratio and size structure constitute basic information in assessing reproductive potential and estimating stock size in fish populations. One hundred fifty-one individuals of Micropogonias furnieri caught by experimental otter trawls, in three zones (inner, central, and outer of Sepetiba Bay between October 1998 and September 1999 were examined. Males outnumbered females (1.3:1.0 in all zones but no significant differences were detected. Only in the outer zone (5.0:1.0 were male/female rates significantly different according to the chi-square test. No temporal differences were observed in sex ratio. Fish size ranged from 81 to 244 mm total length (TL with significant differences in 155 to 185 mm TL size classes, where males predominated, and a slightly higher number of females were observed for the smaller size class (TL = 95-150 mm. Size distribution varied according to the zone, with juveniles predominating in the inner and adults in the outer zone. Spatial difference in size structure observed in this study indicates that the inner bay is a rearing ground during the first life-cycle period, and movement toward the sea occurs as fish increase in size.

  7. Hidden suppression of sex ratio distortion suggests Red queen dynamics between Wolbachia and its dwarf spider host.

    Science.gov (United States)

    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. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  8. Data storage on Russian pesticide producers exposed to dioxin. Sex ratios of third generation of Russian cohort

    Energy Technology Data Exchange (ETDEWEB)

    Amirova, Z.; Kruglov, E. [Environmental Research and Protection Center, Ufa (Russian Federation); Dardynskaia, I. [Univ. of Illinois, School of Public Health, Chicago (United States)

    2004-09-15

    A cohort of Russian workers who produced 2,4,5-T and 2,4,5-TrCP at a chemical factory in Ufa was brought to light in the papers of A. Schecter, J. Ryan and O. Papke. Dioxin exposure was experimentally confirmed by PCDD/Fs determination in blood samples first for a small group of workers and their children. This study permitted to connect the information of medical institutions about chloracne from which a group of young 2,4,5-T workers suffered in 1965-67 with exposure to dioxin. This report presents the results of the detailed study of the third generation of the Russian cohort (247 workers, 314 children and 260 grandchildren). We also present the data on the sex ratio of the second generation for the initial group enlarged by 25% as compared with the group of workers analyzed by J. Ryan et al. (198 workers and 227 children). Besides, as skewed sex ratio had earlier been stated only for paternal descendants, genealogical branches of the cohort representatives were studied.

  9. Effect of Genetic Strain and Sex on Water Absorption and Water-To-Protein Ratio in Chicken Meat

    Directory of Open Access Journals (Sweden)

    MJGS Ferrari

    Full Text Available ABSTRACT The objectives of the present study were to evaluate the water and protein contents and the water-to-protein ratio of chicken parts before and after the pre-chilling process, to compare these results with the values officially recommended by the Brazilian Ministry of Agriculture, and to evaluate the effect of genetic strain and sex on these parameters. Water (% and protein (% contents, and water-to-protein ratio (WPR of boneless and skinless breast (FILLETS and breast with bone and skin (BREAST were determined before (BPC and after (APC carcass pre-chilling. A total of 585 samples were evaluated: 221 fillets/male, 216 breasts/male, 76 fillets/female, and 72 fillets/female of four different broilers strains were evaluated before (BPC and after (APC samples. Water and protein contents and water-to-protein ratio were determined according to the Brazilian legislation. Results showed that there were no significant differences between genetic strains (p<0.05 neither in samples collected before or after the chiller. There were no statistical differences in the parameters studied among genetic strains. However, a high percentage of male breast samples presented water level and water-to-protein ratio above the official limits already before pre-chilling.

  10. Period and cohort trends for mortality and cigarette consumption in England and Wales, 1946 to 1980, with emphasis on sex ratios.

    Science.gov (United States)

    Burch, P R

    1988-01-01

    In an earlier paper (Burch P. R. J. J Chron Dis 1981; 34: 87-103) changes in sex- and age-specific mortality from all causes of death in England and Wales were studied in relation to changes in sex- and age-specific cigarette consumption. The absence of a consistent correlation between the two variables, and the general characteristics of the data, suggested that studies of sex ratios might provide a better test of the hypothesis that the association between smoking and mortality has a causal basis. In this paper temporal changes in the sex ratio of cumulative cigarette consumption by cohort, and of smoking rates by age, are considered in relation to changes in the sex ratio of mortality. Again, no consistent correlations emerge and it is evident that factors other than smoking have played a dominant part in determining recent changes in the sex ratio of mortality in all age groups from 35-39 to 80-84 years. Among these "other factors" are birth cohort effects that can be attributed, in part, to birth cohort changes in the sex ratio of mortality from bronchitis and emphysema. The present results, together with other evidence (vide supra; and Burch P. R. J. J Chron Dis 1984; 37: 148-156), show that great care needs to be exercised when attempts are made to deduce causation from epidemiologic surveys.

  11. First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA

    Science.gov (United States)

    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

  12. First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA.

    Directory of Open Access Journals (Sweden)

    Camryn D Allen

    Full Text Available 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

  13. SECULAR TRENDS AND LATITUDE GRADIENTS IN SEX RATIOS AT BIRTH IN THE FORMER SOVIET REPUBLICS

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    Victor Grech

    2013-01-01

    Full Text Available Background: The male-female ratio at birth (M/F: male births divided by total births, which is anticipated to approximate 0.515, has been shown to exhibit latitude gradients and secular trends. Methods: Annual national data for male and female live births for the 15 countries that comprise the former Soviet Union were obtained from the World Health Organisation for the period 1980–2009 (115,167,569 total live births and analysed with contingency tables. Spearman correlation was also carried out to compare percentage annual gross domestic product growth (GDP% – downloaded from the World Bank and M/F. In this context, GDP% is used as a measure for economic hardship or wellbeing within the populace. Results: There have been overall highly significant secular increases in M/F (p < 0.0001 in the countries and regions investigated. M/F is significantly lower in the three more northern regions (Russian Federation, Baltic States and Central Asia. M/F 0.51324, 0.51335-0.51314 than the two more southern regions (Southern Caucasus and Eastern Europe. M/F 0.51654, 0.51635-0.51672. There was a male excess of 113,818 live births.There was a significant positive correlation between GDP% and M/F for Armenia, Azerbaijan and Uzbekistan. There was a significant negative correlation in Estonia. Conclusion: Previous studies have shown that improving socioeconomic conditions increase M/F, and the converse has also been demonstrated. This is a potential influence in this geographical area since this region has relatively recently emerged from communist rule and experienced an overall economic upturn, but is only partially supported using GDP%. Another factor may be the selective termination of female pregnancies. The latitude gradient parallels that of neighbouring Europe but no theory has been put forward to convincingly explain this finding to date.

  14. Age trend of the male to female sex ratio in surgical gastric cancer patients at a single institution.

    Science.gov (United States)

    Yu, Junxiu; He, Yongjun; Guo, Zhen

    2014-08-21

    In previous reports concerning the association between sex disparity and age, gastric cancer (GC) patients were simply divided into younger and older groups by age. We analyzed the age trend of the male to female sex ratio (MFSR) in GC based on patient sequential age in order to observe the changing process of MFSR with age. One thousand seven hundred fifty-one surgical gastric adenocarcinoma patients aged 26 to 85 years were investigated between January 1996 and December 2010. The patients were grouped by age intervals of 5 years. The Cochran-Armitage trend test was used to determine how the MFSR changed with age. The median age of the 1,751 patients with GC was 60 years (26 to 85 years). There were 1,334 male and 417 female patients (MFSR was 3.20). Cochran-Armitage trend test analysis showed that total MFSR increased significantly with age (Z = 5.964, P trend test showed that MFSR increased significantly with age from 26 to 60 years (Z = 7.433, P trend until 60 years of age. The male GC patients showed an increasing tendency, and female GC patients showed a decreasing tendency with age. This trend reached a plateau phase after 60 years of age.

  15. Latitudinal clines in bill length and sex ratio in a migratory shorebird: a case of resource partitioning?

    Science.gov (United States)

    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.

  16. Variations in sex ratio, feeding, and fecundity of Triatoma dimidiata (Hemiptera: Reduviidae) among habitats in the Yucatan Peninsula, Mexico.

    Science.gov (United States)

    Payet, V; Ramirez-Sierra, M J; Rabinovich, J; Menu, F; Dumonteil, E

    2009-06-01

    Chagas' disease is a major public health concern in most Latin American countries and its prevention is based on insect vector control. Previous work showed that in the Yucatan peninsula of Mexico, houses are transiently infested by adult Triatoma dimidiata, which then fail to establish sustained colonies. The present study was designed to evaluate the seasonality and possible causes of the dispersal of sylvatic T. dimidiata toward the houses and the subsequent failure of colonization. Dispersal was highly seasonal and correlated with temperature, pressure, and wind speed. Analysis of sex ratio, feeding status, and fecundity of sylvatic populations of T. dimidiata indicated a rather low feeding status and low potential fecundity, suggesting that seasonal dispersal may be associated with foraging for better conditions. Also, feeding status and potential fecundity tended to improve in the domestic habitat but remained largely suboptimal, suggesting that these factors may contribute to the ineffective colonization of this habitat.

  17. Seasonal changes in the gonadossomatic index, allometric condition factor and sex ratio of an auchenipterid catfish from eastern Amazonia

    Directory of Open Access Journals (Sweden)

    Tiago Magalhães da Silva Freitas

    Full Text Available The aim of the present study was to evaluate the seasonal pattern of the gonadosomatic index (GSI, condition factor (K, and sex ratio in the catfish Auchenipterichthys longimanus (Siluriformes: Auchenipteridae as an approach to identify its reproductive period. A total of 589 A. longimanus specimens (251 males and 338 females were captured in the rivers of the Caxiuanã National Forest, in the Brazilian state of Pará, between July, 2008 and July, 2009. Among the male specimens, 171 were classified as adults and 80 as juveniles, while there were 249 adults and 89 juvenile females. Using a sinusoidal equation, analysis of the GSI revealed a reproductive asynchrony between the genders, with males attaining their highest GSI values in January, while females peaked in March. For males, the sinusoidal regression for GSI values was significant only when used the complete data set (P=0.001, wears no trend was identified for bimonthly means (P=0.136. For females, by contrast, significant values were obtained for both the complete data set (P=0.012 and bimonthly GSI means (P=0.026. For the condition factor, the sinusoidal equation returned significant seasonal variation in both raw data (P=0.02 and with mean values (P=0.00 for males, but only with raw data for females (P=0.04, which appears to reflect variation in the energy budget between genders. With regard to the sex ratio, more reproductive females were captured than males in January and March, 2009, which suggests a pattern of segregation related to the reproductive process. These parameters are fundamental to the assessment, protection, and management of natural fish stocks, as well as providing guidelines for the development of conservation strategies.

  18. Periconceptional Multivitamin Supplementation Containing Folic Acid and Sex Ratio at Birth in a Chinese Population: a Prospective Cohort Study.

    Science.gov (United States)

    Zheng, Xiaoying; Pei, Lijun; Chen, Gong; Song, Xinming; Wu, Jilei; Ji, Ying

    2015-07-01

    To determine whether periconceptional use of multivitamin supplements containing folic acid increases the occurrence of male births in a Chinese population. A prospective cohort study was carried out in 18 counties in four provinces of China. Participants were naturally and voluntarily divided into an intervention group (who took a multivitamin pill containing folic acid, n = 25,418) and a control group (who did not take any multivitamin, n = 26,580). Multivitamin supplements containing folic acid was ascertained before pregnancy. Pregnant women were followed through the first trimester of pregnancy and the outcome of pregnancy (i.e. livebirth, stillbirth, or fetal death; sex at birth) was recorded. A total of 52,043 pregnancies and 51,998 births were recorded between September 2000 and August 2002. The proportion of males born to women who did and did not take the multivitamin were 54.8% (n = 13,935) and 54.0% (n = 11,483), respectively. The male to female sex ratios at birth among women who did and did not take the multivitamin were 117:100 and 121:100, respectively. The risk ratio was 1.03 [95% confidence interval 0.99, 1.06] after adjusting for confounding factors. These findings suggest that periconceptional multivitamin supplementation containing folic acid is not associated with an increased likelihood of male births in a Chinese population. However, these results may have been affected by induced abortion or selective termination of pregnancy, and the findings must therefore be cautiously interpreted. © 2015 John Wiley & Sons Ltd.

  19. Reproductive and behavioral aspects of red-winged tinamous (Rhynchotus rufescens in groups with different sex ratios

    Directory of Open Access Journals (Sweden)

    VU Cromberg

    2007-09-01

    Full Text Available The aim of this research study was to evaluate the reproductive performance of tinamous submitted to five different male:female ratios. The study was carried out with 72 birds in a randomized experimental design with 4 replications. Tinamous were housed in cages, using the ratios of one (1:1, two (2:1, three (3:1 and four (4:1 females per male, and also one male was housed with three females individually (3R:1, in a rotational system. Reproductive records of the breeding season from September 2004 to March 2005 were used. The reproductive traits studied were: number of eggs laid, fertility, and percentage of eggs damaged and cracked by pecking. Nonparametric analyses of these traits were performed using Kruskal-Wallis test. Two replications of treatments 1:1 and 4:1, and one of treatment 2:1 were video-taped for three days, 12 hours/day. The videotapes were sampled according to the scan method to fit an ethogram. Birds were also watched for one hour per day to study dominance and agonistic behavior. None of the reproductive traits was affected by mating sex ratio (p<0.05. Female dominance could be related to displacement behavior (r=1.00, and male sitting in immobility plus sitting in activity behaviors were related to lower number of damaged eggs (r=-0.90. Social dominance was indirectly determined by displacement behavior in the study situation. A large number of damaged eggs occurred in all treatments, thereby not allowing a clear conclusion on the best male:female ratio.

  20. Parallel distribution of sexes within left and right uterine horns in Holstein dairy cows: evidence that the effect of side of pregnancy on sex ratio could be breed-specific in cattle.

    Science.gov (United States)

    Gharagozlou, F; Vojgani, M; Akbarinejad, V; Niasari-Naslaji, A; Hemmati, M; Youssefi, R

    2013-11-30

    Dissimilar distribution of male and female calves within left and right uterine horns has been observed in beef cows. A retrospective study was conducted to investigate the effect of side of pregnancy on secondary sex ratio in Holstein dairy cows. Data associated with sex of calves, side of pregnancy, sire, dam, parity number of dam, AI technician, season and year were retrieved from the database of a Holstein dairy farm. In total, data consisted of 6515 birth records from 3155 dams and 244 sires across years 2001-2010. Data were analyzed using logistic regression. There was no difference in proportion of male and female calves between left (52.9% and 47.1%, respectively) and right (53.2% and 46.8%, respectively) uterine horns (P>0.05). AI technician, year, season and parity of dam did not affect secondary sex ratio (P>0.05). Secondary sex ratio of left and right uterine horns, and consequently, overall secondary sex ratio (53.1%) were skewed toward males as compared with hypothetical secondary sex ratio of 50% (Phorns in Holstein dairy cows. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Linear and threshold analysis of direct and maternal genetic effects for secondary sex ratio in Iranian buffaloes.

    Science.gov (United States)

    Ghavi Hossein-Zadeh, Navid

    2014-08-01

    The objective of this study was to estimate variance components and genetic parameters for secondary sex ratio (SSR) in Iranian buffaloes. Calving records from April 1995 to June 2010 comprising 15,207 calving events from the first three lactations of 1066 buffalo herds of Iran were analyzed using linear and threshold animal models to estimate variance components, heritabilities and genetic correlations between direct and maternal genetic effects for SSR. Linear and threshold animal models included direct and maternal genetic effects with covariance between them and maternal permanent environmental effects were implemented by Gibbs sampling methodology. Posterior means of direct and maternal heritabilities and repeatability for SSR obtained from linear animal model were 0.15, 0.10, and 0.17, respectively. Threshold estimates of direct and maternal heritabilities and repeatability for SSR were 0.48, 0.27, and 0.52, respectively. The results showed that the correlations between direct and maternal genetic effects of SSR were negative and high in both models. In addition, the ratios of maternal permanent environmental variance were low. Exploitable genetic variation in SSR can take advantage of sexual dimorphism for economically important traits which may facilitate greater selection intensity and thus greater response to selection, as well as reducing the replacement costs. Threshold animal model may be applied in selection programs where animals are to be genetically ranked for female rate.

  2. Birth order, sibling sex ratio, handedness, and sexual orientation of male and female participants in a BBC internet research project.

    Science.gov (United States)

    Blanchard, Ray; Lippa, Richard A

    2007-04-01

    This study investigated the relations among sexual orientation, fraternal birth order (number of older brothers), and hand-preference. The participants were 87,798 men and 71,981 women who took part in a Web-based research project sponsored by the British Broadcasting Corporation (BBC). The results yielded some evidence confirming prior findings that non-right-handedness is associated with homosexuality in men and women, that older brothers increase the odds of homosexuality in men, and that the effect of older brothers on sexual orientation is limited to right-handed men. The evidence was weaker than in previous studies, however, probably because the usual relations among the variables of interest were partially obscured by the effects of other factors. Thus, the homosexual men and women had higher rates of non-right-handedness than their heterosexual counterparts, but the strongest handedness finding for both sexes was a marked tendency for participants who described themselves as ambidextrous also to describe themselves as bisexual. The birth order data were strongly affected by a tendency for the male participants to report an excess of older sisters, and the female participants to report an excess of older brothers. Statistical analyses confirmed that this was an artifact of the parental stopping rule, "Continue having children until you have offspring of both sexes." In subsequent analyses, participants were divided into those who did and did not have younger siblings, on the grounds that the data of the former would be less contaminated by the stopping rule. In the former subsample, the right-handed homo/bisexual males showed the typical high ratio of older brothers to older sisters, whereas the non-right-handed homo/bisexual males did not.

  3. Sex ratio in normal and disomic sperm: Evidence that the extra chromosome 21 preferentially segregates with the Y chromosome

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, D.K.; Millie, E.A.; Hassold, T.J. [Case Western Univ., Cleveland, OH (United States)]|[Univ. Hospitals of Cleveland, OH (United States)] [and others

    1996-11-01

    In humans, deviations from a 1:1 male:female ratio have been identified in both chromosomally normal and trisomic live births: among normal newborns there is a slight excess of males, among trisomy 18 live borns a large excess of females, and among trisomy 21 live borns an excess of males. These differences could arise from differential production of or fertilization by Y- or X-bearing sperm or from selection against male or female conceptions. To examine the proportion of Y- and X- bearing sperm in normal sperm and in sperm disomic for chromosomes 18 or 21, we used three-color FISH (to the X and Y and either chromosome 18 or chromosome 21) to analyze > 300,000 sperm from 24 men. In apparently normal sperm, the sex ratio was nearly 1:1 (148,074 Y-bearing to 148,657 X-bearing sperm), and the value was not affected by the age of the donor. Certain of the donors, however, had significant excesses of Y- or X-bearing sperm. In disomy 18 sperm, there were virtually identical numbers of Y- and X-bearing sperm; thus, the excess of females in trisomy 18 presumably is due to selection against male trisomic conceptions. In contrast, we observed 69 Y-bearing and 44 X-bearing sperm disomic for chromosome 21. This is consistent with previous molecular studies, which have identified an excess of males among paternally derived cases of trisomy 21, and suggests that some of the excess of males among Down syndrome individuals is attributable to a nondisjunctional mechanism in which the extra chromosome 21 preferentially segregates with the Y chromosome. 17 refs., 2 tabs.

  4. Dosimetry of radium-223 and progeny

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, D.R. [Pacific Northwest National Lab., Richland, WA (United States); Sgouros, G. [Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    1999-01-01

    Radium-223 is a short-lived (11.4 d) alpha emitter with potential applications in radioimmunotherapy of cancer. Radium-223 can be complexed and linked to protein delivery molecules for specific tumor-cell targeting. It decays through a cascade of short-lived alpha- and beta-emitting daughters with emission of about 28 MeV of energy through complete decay. The first three alpha particles are essentially instantaneous. Photons associated with Ra-223 and progeny provide the means for tumor and normal-organ imaging and dosimetry. Two beta particles provide additional therapeutic value. Radium-223 may be produced economically and in sufficient amounts for widescale application. Many aspects of the chemistry of carrier-free isotope preparation, complexation, and linkage to the antibody have been developed and are being tested. The radiation dosimetry of a Ra-223-labeled antibody shows favorable tumor to normal tissue dose ratios for therapy. The 11.4-d half-life of Ra-223 allows sufficient time for immunoconjugate preparation, administration, and tumor localization by carrier antibodies before significant radiological decay takes place. If 0.01 percent of a 37 MBq (1 mCi) injection deposits in a one gram tumor mass, and if the activity is retained with a typical effective half-time (75 h), the absorbed dose will be 163 mGy MBq{sup {minus}1} (600 rad mCi{sup {minus}1}) administered. 49 refs., 5 figs., 2 tabs.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  7. Plasmodium falciparum gametocyte carriage, emergence, clearance and population sex ratios in anaemic and non-anaemic malarious children

    Directory of Open Access Journals (Sweden)

    Grace Olusola Gbotosho

    2011-08-01

    Full Text Available Anaemia in falciparum malaria is associated with an increased risk of gametocyte carriage, but its effects on transmission have not been extensively evaluated in malarious children. Plasmodium falciparum gametocyte carriage, emergence, clearance, population sex ratios (SR (defined as the proportion of gametocytes that are male, inbreeding rates and temporal changes in SR were evaluated in 840 malarious children. Gametocyte carriage pre-treatment was at a level of 8.1%. Anaemia at enrolment was an independent risk factor for gametocyte carriage post-treatment. The emergence of gametocytes seven days post-treatment was significantly more frequent in anaemic children (7/106 vs. 10/696, p = 0.002. In the initially detected gametocytes, the proportion of children with a male-biased SR (MBSR (> 0.5 was significantly higher in anaemic children (6/7 vs. 3/10, p = 0.027. Pre-treatment SR and estimated inbreeding rates (proportion of a mother's daughters fertilised by her sons were similar in anaemic and non-anaemic children. Pre-treatment SR became more female-biased in non-anaemic children following treatment. However, in anaemic children, SR became male-biased. Anaemia was shown to significantly increase gametocyte emergence and may significantly alter the SR of emerging gametocytes. If MBSR is more infective to mosquitoes at low gametocytaemia, then these findings may have significant implications for malaria control efforts in endemic settings where malaria-associated anaemia is common.

  8. Biased sex ratio and low population density increase male mating success in the bug Nysius huttoni (Heteroptera: Lygaeidae)

    Science.gov (United States)

    Wang, Qiao; He, Xiong Zhao; Yang, Linghuan; Hedderley, Duncan; Davis, Lorraine K.

    2009-01-01

    Demographic factors such as operational sex ratio (OSR) and local population density (LPD) are temporally and spatially dynamic in the natural environment but the influence of these variables on male mating success and the mechanisms behind it are still poorly understood and highly controversial. Here, we manipulated the OSR and LPD of a seed bug, Nysius huttoni, and carried out a series of mating trials to test how these variables affected male mating success. The two demographic factors had no significant interactions, suggesting that they affect male mating success independently in N. huttoni. In this species male mating success was significantly higher in both male- and female-biased OSR than in even OSR. It is suggested that, in male-biased OSR, the increased intensity of competition and interference does not result in lower male mating success; rather, males may make more effort in courting and females may have more chance to encounter better males, resulting in higher male mating success. In female-biased OSR, females may become less choosy and less likely to reject male mating attempt, leading to the higher male mating success. Lower male mating success in N. huttoni in high LPD may be due to increased interference between males and/or delayed female receptiveness for mating. OSR had a stronger effect on male mating success than LPD in N. huttoni, suggesting that OSR and LPD affect mating success in different ways and intensities.

  9. Seasonal variation in female mate choice and operational sex ratio in wild populations of an annual fish, Austrolebias reicherti.

    Science.gov (United States)

    Passos, Carlos; Tassino, Bettina; Reyes, Federico; Rosenthal, Gil G

    2014-01-01

    The intensity of mating competition and the potential benefits for female of mating with certain males can be influenced by several extrinsic factors, such that behavioral decisions can be highly context-dependent. Short-lived species with a single reproductive season are a unique model to study context-sensitive mating decisions. Through exhaustive sampling in the field and simultaneous choice tests in the laboratory, we evaluated operational sex ratio (OSR) and female mate choice at the beginning and end of the reproductive season in the annual killifish Austrolebias reicherti. We found seasonal change in both OSR and female mate choice. At the start of the reproductive season the OSR did not deviate from parity, and females preferred larger males. Later in the reproductive season, while the proportion of males in the ponds decreased, females became unselective with respect to male size. The particular biological cycle of annual killifish, where both life expectancy and mating opportunities decline sharply over a short timescale, could account for the seasonal change in female choice. Reduction in choosiness could arise from diminished reproductive prospects due to a decline in male availability. Moreover, as the end of the season approaches, any benefits of choosiness are presumably reduced: a female's fitness will be higher if she mates with any male than if she forgoes reproduction and dies. Future work will disentangle the mechanisms underlying seasonal changes in mating preferences, notably direct responses to demographic factors, environmental cues, or intrinsic changes during development.

  10. Sex Chromosome Drive

    OpenAIRE

    Helleu, Quentin; Gérard, Pierre R.; Montchamp-Moreau, Catherine

    2015-01-01

    Sex chromosome drivers are selfish elements that subvert Mendel's first law of segregation and therefore are overrepresented among the products of meiosis. The sex-biased progeny produced then fuels an extended genetic conflict between the driver and the rest of the genome. Many examples of sex chromosome drive are known, but the occurrence of this phenomenon is probably largely underestimated because of the difficulty to detect it. Remarkably, nearly all sex chromosome drivers are found in t...

  11. [Evaluation of Reproductive Health of Chickens and Their Progeny at a Chronic Effect of 131I].

    Science.gov (United States)

    Boudarkov, V A

    2015-01-01

    A reproductive health of hens exposed to 131I in a 30-day period with daily quantities ranging from 0.11 to 4.6 MBq/kg and 6 progenies of their offspring was evaluated. We determined that 131I did not change significantly the reproductive potential of hens if administered at a dose of 0.11 MBq, while it raised at 1.1 MBq, progressively decreased after a short-time increase at 2.1 MBq and was inhabited up to its irreversible extinction at 4.6 MBq. Irrespective of the isotope quantity administered, a decline occurred in the birth rate of the progeny where hens dominated in the sex composition. The reproductive potential (i.e., laying capacity) of the offspring of three chicken progenies that had been administered 131I at 0.11 MBq/kg, progenies 3 and 5 that had been administered 1.1 MBq/kg and progeny 1 affected with 2.1 MBq/kg increased, while for chicken progenies 1, 2, 4 and 6 that had been given 131I at 1.1. MBq/kg the reproductive capacity was within the normal range or decreased.

  12. Birth Order and Sibling Sex Ratio in a Population with High Fertility: Are Turkish Male to Female Transsexuals Different?

    Science.gov (United States)

    Bozkurt, Ali; Bozkurt, Ozlem Hekim; Sonmez, Ipek

    2015-07-01

    Western studies have consistently found that androphilic (sexually attracted to men) male-to-female transsexuals have a later birth order and a relative excess of brothers compared with appropriate control participants. However, non-Western studies on birth order and sibling sex ratio in androphilic males (transsexual or non-transsexual) are rare. The objective of the study was to test the hypothesis that androphilic male-to-female transsexuals have a late birth order and a relative excess of brothers in a non-Western culture with a higher fertility rate. The participants were 60 androphilic male-to-female transsexuals and 61 male heterosexual controls. The transsexual participants had significantly more older brothers than the control participants, but the groups did not differ in their numbers of older sisters, younger brothers, or younger sisters. The foregoing pattern is usually referred to as the "fraternal birth order effect." Slater's and Berglin's Indexes both showed that the mean birth order of the control participants was very close to that expected from a random sample drawn from a demographically stable population whereas the mean birth order of the transsexual participants was later. A measure of sibship composition, brothers/all siblings, showed that the transsexual group had a higher proportion of male siblings compared with the control group. In conclusion, the present study found that Turkish androphilic male-to-female transsexuals show the same high fraternal birth order that has been found in comparable androphilic samples in Western Europe, North America, and the South Pacific, which suggests a common underlying biological causal mechanism.

  13. Social determinants of adult sex ratios and racial/ethnic disparities in transmission of HIV and other sexually transmitted infections in the USA.

    Science.gov (United States)

    Pouget, Enrique Rodriguez

    2017-09-19

    In Black population centres in the USA, adult sex ratios (ASRs) are strongly female-biased primarily due to high male incarceration and early mortality rates. I explore the system of social determinants that shape these ASRs, and describe their apparent consequences. Evidence suggests that female-biased ASRs play a role, along with racial residential segregation, to increase mixing between core and peripheral members of sexual networks, facilitating transmission of human immunodeficiency virus and other sexually transmitted infections. Unique historical factors underlie Black male incarceration and mortality rates in the USA, making comparisons with other groups or other countries challenging.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

  14. Are environmental factors responsible for geographic variation in the sex ratio of the Greenlandic seed-bug Nysius groenlandicus?

    DEFF Research Database (Denmark)

    Bøcher, Jens Jensenius; Nachman, Gøsta Støger

    2010-01-01

    Until recently nothing indicated an unequal sex ratio in the widespread Greenland seed-bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae). However, recently populations more or less devoid of males were discovered in high arctic Northeast Greenland. This initiated an inspection of th...

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

    Directory of Open Access Journals (Sweden)

    Juan Zhang

    2016-01-01

    Full Text Available 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.

  16. What causes female bias in the secondary sex ratios of the dioecious woody shrub Salix sitchensis colonizing a primary successional landscape?

    Science.gov (United States)

    C. Che-Castaldo; C. M. Crisafulli; J. G. Bishop; W. F. Fagan

    2015-01-01

    PREMISE OF THE STUDY: Females often outnumber males in Salix populations, although the mechanisms behind female bias are not well understood and could be caused by both genetic and ecological factors. We investigated several ecological factors that could bias secondary sex ratios of Salix sitchensis colonizing Mount St. Helens after the 1980 eruption.M ETHODS...

  17. Genetic Diversity of the Invasive Gall Wasp Leptocybe invasa (Hymenoptera: Eulophidae and of its Rickettsia Endosymbiont, and Associated Sex-Ratio Differences.

    Directory of Open Access Journals (Sweden)

    Francesco Nugnes

    Full Text Available The blue-gum chalcid Leptocybe invasa Fisher & LaSalle (Hymenoptera: Eulophidae is a gall wasp pest of Eucalyptus species, likely native to Australia. Over the past 15 years it has invaded 39 countries on all continents where eucalypts are grown. The worldwide invasion of the blue gum chalcid was attributed to a single thelytokous morphospecies formally described in 2004. Subsequently, however, males have been recorded in several countries and the sex ratio of field populations has been found to be highly variable in different areas. In order to find an explanation for such sex ratio differences, populations of L. invasa from a broad geographical area were screened for the symbionts currently known as reproductive manipulators, and both wasps and symbionts were genetically characterized using multiple genes. Molecular analyses suggested that L. invasa is in fact a complex of two cryptic species involved in the rapid and efficient spread of the wasp, the first recovered from the Mediterranean region and South America, the latter from China. All screened specimens were infected by endosymbiotic bacteria belonging to the genus Rickettsia. Two closely related Rickettsia strains were found, each infecting one of the two putative cryptic species of L. invasa and associated with different average sex ratios. Rickettsia were found to be localized in the female reproductive tissues and transovarially transmitted, suggesting a possible role of Rickettsia as the causal agent of thelytokous parthenogenesis in L. invasa. Implications for the variation of sex ratio and for the management of L. invasa are discussed.

  18. Nuclear genes with sex bias in Ruditapes philippinarum (Bivalvia, veneridae): Mitochondrial inheritance and sex determination in DUI species.

    Science.gov (United States)

    Milani, Liliana; Ghiselli, Fabrizio; Nuzhdin, Sergey V; Passamonti, Marco

    2013-11-01

    Mitochondria are inherited maternally in most metazoans, but in bivalves with Doubly Uniparental Inheritance (DUI) a mitochondrial lineage is transmitted through eggs (F-type), and another through sperm (M-type). In DUI species, a sex-ratio distortion of the progeny was observed: some females produce a female-biased offspring (female-biased family), others a male-biased progeny (male-biased family), and others a 50:50 sex-ratio. A peculiar segregation pattern of M-type mitochondria in DUI organisms appears to be correlated with the sex bias of these families. According to a proposed model for the inheritance of M-type mitochondria in DUI, the transmission of sperm mitochondria is controlled by three nuclear genes, named W, X, and Z. An additional S gene with different dosage effect would be involved in sex determination. In this study, we analyzed structure and localization of three transcripts (psa, birc, and anubl1) with specific sex and family biases in the Manila clam Ruditapes philippinarum. In situ hybridization confirmed the localization of these transcripts in gametogenic cells. In other animals, homologs of these genes are involved in reproduction and ubiquitination. We hypothesized that these genes may have a role in sex determination and could also be responsible for the maintenance/degradation of spermatozoon mitochondria during embryo development of the DUI species R. philippinarum, so that we propose them as candidate factors of the W/X/Z/S system. © 2013 Wiley Periodicals, Inc.

  19. Determine sex ratios of green turtles along the U.S. West Coast through examinations of hormones

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A testosterone (T) enzyme-linked immunosorbent assay (ELISA) was validated for use with green turtle plasma in order to determine the sex of juvenile turtles. We...

  20. DNA methylation of the gonadal aromatase (cyp19a promoter is involved in temperature-dependent sex ratio shifts in the European sea bass.

    Directory of Open Access Journals (Sweden)

    Laia Navarro-Martín

    2011-12-01

    Full Text Available Sex ratio shifts in response to temperature are common in fish and reptiles. However, the mechanism linking temperature during early development and sex ratios has remained elusive. We show in the European sea bass (sb, a fish in which temperature effects on sex ratios are maximal before the gonads form, that juvenile males have double the DNA methylation levels of females in the promoter of gonadal aromatase (cyp19a, the enzyme that converts androgens into estrogens. Exposure to high temperature increased the cyp19a promoter methylation levels of females, indicating that induced-masculinization involves DNA methylation-mediated control of aromatase gene expression, with an observed inverse relationship between methylation levels and expression. Although different CpGs within the sb cyp19a promoter exhibited different sensitivity to temperature, we show that the increased methylation of the sb cyp19a promoter, which occurs in the gonads but not in the brain, is not a generalized effect of temperature. Importantly, these effects were also observed in sexually undifferentiated fish and were not altered by estrogen treatment. Thus, methylation of the sb cyp19a promoter is the cause of the lower expression of cyp19a in temperature-masculinized fish. In vitro, induced methylation of the sb cyp19a promoter suppressed the ability of SF-1 and Foxl2 to stimulate transcription. Finally, a CpG differentially methylated by temperature and adjacent to a Sox transcription factor binding site is conserved across species. Thus, DNA methylation of the aromatase promoter may be an essential component of the long-sought-after mechanism connecting environmental temperature and sex ratios in vertebrate species with temperature-dependent sex determination.

  1. Analysis of case-parent trios for imprinting effect using a loglinear model with adjustment for sex-of-parent-specific transmission ratio distortion.

    Science.gov (United States)

    Huang, Lam Opal; Infante-Rivard, Claire; Labbe, Aurélie

    2017-08-01

    Transmission ratio distortion (TRD) is a phenomenon where parental transmission of disease allele to the child does not follow the Mendelian inheritance ratio. TRD occurs in a sex-of-parent-specific or non-sex-of-parent-specific manner. An offset computed from the transmission probability of the minor allele in control-trios can be added to the loglinear model to adjust for TRD. Adjusting the model removes the inflation in the genotype relative risk (RR) estimate and Type 1 error introduced by non-sex-of-parent-specific TRD. We now propose to further extend this model to estimate an imprinting parameter. Some evidence suggests that more than 1% of all mammalian genes are imprinted. In the presence of imprinting, for example, the offspring inheriting an over-transmitted disease allele from the parent with a higher expression level in a neighboring gene is over-represented in the sample. TRD mechanisms such as meiotic drive and gametic competition occur in a sex-of-parent-specific manner. Therefore, sex-of-parent-specific TRD (ST) leads to over-representation of maternal or paternal alleles in the affected child. As a result, ST may bias the imprinting effect when present in the sample. We propose a sex-of-parent-specific transmission offset in adjusting the loglinear model to account for ST. This extended model restores the correct RR estimates for child and imprinting effects, adjusts for inflation in Type 1 error, and improves performance on sensitivity and specificity compared to the original model without ST offset. We conclude that to correctly interpret the association signal of an imprinting effect, adjustment for ST is necessary to ensure valid conclusions.

  2. Sex differences in college students' free drawings and their relationship to 2D:4D ratio and recalled childhood play behavior.

    Science.gov (United States)

    Rothkopf, Ian; Turgeon, Sarah M

    2014-02-01

    In a prior study, we observed that female-typical characteristics in elementary school girls' drawings were correlated with a feminized digit ratio (2D:4D), a marker for prenatal androgen exposure. However, this observation was limited to older girls, suggesting that social factors mediate the relationship between 2D:4D and drawing. To examine the hypothesis that the influence of prenatal androgen on girls' drawing is mediated by an effect of early androgens on sex-typical behavior, we examined 2D:4D, free drawings, and scores on the Recalled Childhood Gender Identity (RCGI) Questionnaire in a population of college students. Characteristics of participants' free drawings were assessed and those that showed sex differences were compared with 2D:4D and RCGI scores. Men had smaller 2D:4D ratios than women, used fewer total colors, used fewer pinks, purples, and blues, and had higher gender-typical scores on the RCGI. Women's drawings were more likely to contain flowers and animals and men's drawings were more likely to represent sports. Within-sex RCGI and 2D:4D scores were not significantly correlated. Significant within-sex relationships between 2D:4D and RCGI and drawing behavior were observed but the effects appeared to be independent; the hypothesis that gender-typical childhood behavior mediates the effect of prenatal androgen on drawing characteristics was not supported.

  3. The contrasting effects of ad libitum and restricted feeding of a diet very high in saturated fats on sex ratio and metabolic hormones in mice.

    Science.gov (United States)

    Alexenko, Andrei P; Mao, Jiude; Ellersieck, Mark R; Davis, Angela M; Whyte, Jeffrey J; Rosenfeld, Cheryl S; Roberts, R Michael

    2007-10-01

    Skewing of the sex ratio towards males occurs among pups born to mice fed a very high saturated fat (VHF) diet. In the present study, we tested whether the fat content of the VHF diet rather than the number of calories consumed is responsible for this effect. Eight-week-old NIH Swiss mice were placed on the VHF diet either ad libitum (VHF) or in a restricted manner (VHF-R). The VHF-R mice gained weight at a similar rate to controls fed a standard chow diet. Mice were bred at 15 wk and subsequently at 26 wk and 35 wk of age. Overall, the VHF, VHF-R, and control groups delivered 244, 242, and 274 pups, respectively, with male proportions of 0.60, 0.43, and 0.48, respectively. The pup sex ratios of the VHF group (favoring males) and VHF-R group (favoring females) each differed from 0.5 (P diet groups, maternal body weight had no effect on sex ratio. Serum leptin concentrations among the dams were similar in the VHF and VHF-R groups but higher than in the control group, while the IGF1 and corticosterone levels were comparable in all three groups. Therefore, the atypical sex ratios of offspring born to dams on the VHF diet seem to be influenced by the amount of fat consumed. Since males fed the VHF diet had neither more Y-sperm nor sired more sons than daughters, the dietary effects are manifested exclusively through the female.

  4. Rapid rise and fall of selfish sex-ratio X chromosomes in Drosophila simulans: spatiotemporal analysis of phenotypic and molecular data.

    Science.gov (United States)

    Bastide, Héloïse; Cazemajor, Michel; Ogereau, David; Derome, Nicolas; Hospital, Frédéric; Montchamp-Moreau, Catherine

    2011-09-01

    Sex-ratio drive, which has been documented in several Drosophila species, is induced by X-linked segregation distorters. Contrary to Mendel's law of independent assortment, the sex-ratio chromosome (X(SR)) is inherited by more than half the offspring of carrier males, resulting in a female-biased sex ratio. This segregation advantage allows X(SR) to spread in populations, even if it is not beneficial for the carriers. In the cosmopolitan species D. simulans, the Paris sex-ratio is caused by recently emerged selfish X(SR) chromosomes. These chromosomes have triggered an intragenomic conflict, and their propagation has been halted over a large area by the evolution of complete drive suppression. Previous molecular population genetics analyses revealed a selective sweep indicating that the invasion of X(SR) chromosomes was very recent in Madagascar (likely less than 100 years ago). Here, we show that X(SR) chromosomes are now declining at this location as well as in Mayotte and Kenya. Drive suppression is complete in the three populations, which display little genetic differentiation and share swept haplotypes, attesting to a common and very recent ancestry of the X(SR) chromosomes. Patterns of DNA sequence variation also indicate a fitness cost of the segmental duplication involved in drive. The data suggest that X(SR) chromosomes started declining first on the African continent, then in Mayotte, and finally in Madagascar and strongly support a scenario of rapid cycling of X chromosomes. Once drive suppression has evolved, standard X(ST) chromosomes locally replace costly X(SR) chromosomes in a few decades.

  5. Sex determination from hand dimensions and index/ring finger length ratio in North Saudi population: Medico-legal view

    Directory of Open Access Journals (Sweden)

    Mahrous AbdelBasset Ibrahim

    2016-12-01

    Conclusion: By using the anthropometric measurements of hand dimensions, sex can be estimated with a high accuracy. It is, therefore, an important tool to be included in forensic identification when a hand is detected at the scene in mass disasters and criminal situations.

  6. Effect of extra-pair paternity and parental quality on brood sex ratio in the scarlet rosefinch Carpodacus erythrinus

    Czech Academy of Sciences Publication Activity Database

    Poláková, Radka; Schnitzer, J.; Vinkler, Michal; Bryja, Josef; Munclinger, P.; Albrecht, Tomáš

    2012-01-01

    Roč. 61, 3-4 (2012), s. 225-232 ISSN 0139-7893 R&D Projects: GA MŠk LC06073; GA ČR GA206/06/0851 Institutional support: RVO:68081766 Keywords : sex allocation * extra-pair mating * parental attractiveness Subject RIV: EG - Zoology Impact factor: 0.494, year: 2012

  7. Effect of water temperature on sex ratio and growth rate of juvenile Pelteobagrus fulvidraco, P. vachelli and hybrids [P. fulvidraco (♀ × P. vachelli (♂

    Directory of Open Access Journals (Sweden)

    Guosong Zhang

    2016-05-01

    Full Text Available In order to explore the effect of water temperature on sex ratio and growth rate, we reared the juveniles of Pelteobagrus fulvidraco, Pelteobagrus vachelli and the hybrids from P. fulvidraco (♀ × P. vachelli (♂ at 6 different water temperature conditions (20, 23, 26, 29, 32 and 34 °C in this study. The results showed the population of male and female fish at the ratio of 1:1 when the fish from three groups was cultured at water temperatures of 26, 29, 32 and 34 °C for 45 days. The analysis for the ratio between male and female reared at various temperatures suggests that the sex differentiation in P. fulvidraco, P. vachelli and the hybrids was not temperature-dependent sex determination (TSD. Based on the mathematical relationship between weight gain (WG and water temperature, the maximum growth rate of P. fulvidraco, P. vachelli and the hybrids was achieved at 27.53, 28.36 and 28.40 °C, respectively. There is only very negligible difference between temperatures for the highest weight gain determined through mathematical modeling. However, weight gain determination shows comparatively higher growth rate at all test temperature. We initially deduced that the hybrids from P. fulvidraco (♀ × P. vachelli (♂ have heterosis. Our results indicated that the hybrids were very suitable for commercial aquaculture.

  8. Sex-ratio, seasonality and long-term variation in maturation and spawning of the brown shrimp Crangon crangon (L.) in the German Bight (North Sea)

    Science.gov (United States)

    Siegel, V.; Damm, U.; Neudecker, T.

    2008-12-01

    Aspects of the reproductive and maturation biology of the brown shrimp Crangon crangon (L.) were studied in various subareas of the German Bight (North Sea). The size-specific sex ratio of C. crangon was examined based on length frequency distribution data. The sex ratio for the smallest size groups at which sex was determined was typically around 0.5, indicating an even ratio between males and females. The proportion of females decreased in the 30-45 mm size range. In length classes larger than 50 mm, the proportion of females constantly increases to 100% at around 60 mm total length. We concluded that sex reversal from male to female may not occur in C. crangon. Size at sexual maturity was determined from the proportion of ovigerous females. Size at maturity ( L 50) was estimated as 55.4 and 62.0 mm total length for spring and winter data, respectively. The seasonal spawning cycle was studied over the period 1958-2005. Between mid February and late June and for size classes larger than 65 mm ovigerous shrimps exceeded 80% and reached up to 100% of the females in the population. This period can be seen as the core spawning season. From early August to early December the proportion of ovigerous shrimps in the female population is very low. Interannual differences in the seasonal process are obvious with a dramatic decline in C. crangon reproductive success in the late 1980s. Various options are discussed for the reasons of the decline and recovery of the reproductive performance.

  9. Temperatures for fertilization and hatching and their influence on determining the sex ratio of the silver catfish Rhamdia quelen - doi: 10.4025/actascibiolsci.v32i2.5261 Temperatures for fertilization and hatching and their influence on determining the sex ratio of the silver catfish Rhamdia quelen - doi: 10.4025/actascibiolsci.v32i2.5261

    Directory of Open Access Journals (Sweden)

    Ricardo da Silva Longo

    2010-05-01

    Full Text Available This study aimed to evaluate the effects of water temperature during fertilization and egg incubation in the determination of the sex ratio of fingerlings of silver catfish Rhamdia quelen. Water temperatures of 19, 25 and 30°C were used during the egg fertilizations, and the eggs were then incubated at temperatures of 19, 25 or 30°C for each fertilization temperature condition. An increase in temperature reduced the fertilization rate of R. quelen, while the final number of fish was reduced when a lower temperature was used during egg incubation. The temperatures of fertilization and incubation that were tested did not alter the sex ratio.This study aimed to evaluate the effects of water temperature during fertilization and egg incubation in the determination of the sex ratio of fingerlings of silver catfish Rhamdia quelen. Water temperatures of 19, 25 and 30°C were used during the egg fertilizations, and the eggs were then incubated at temperatures of 19, 25 or 30°C for each fertilization temperature condition. An increase in temperature reduced the fertilization rate of R. quelen, while the final number of fish was reduced when a lower temperature was used during egg incubation. The temperatures of fertilization and incubation that were tested did not alter the sex ratio.

  10. Sex ratio and body size in Cobitis elongatoides and Sabanejewia balcanica (Cypriniformes; Cobitidae) from a thermal spring

    Czech Academy of Sciences Publication Activity Database

    Bohlen, Jörg; Freyhof, J.; Nolte, A.

    2008-01-01

    Roč. 57, 1-2 (2008), s. 191-197 ISSN 0139-7893. [International Conference Loaches of the genus Cobitis and related genera. Šibenik, 24.09.2006-29.09.2006] R&D Projects: GA ČR GA206/05/2556; GA AV ČR IAA600450508 Institutional research plan: CEZ:AV0Z50450515 Keywords : environmental sex determination * Fish er's principle * cobitine loach Subject RIV: EG - Zoology Impact factor: 0.522, year: 2008

  11. The influence of migration on secular trends in sex ratios at birth in cuba in the past fifty years.

    Science.gov (United States)

    Grech, V

    2014-08-01

    Secular trends have been found in the male-female ratio at birth (M/F: male births divided by total births) in various countries and this ratio is anticipated to approximate 0.515. Annual national data for male and female live births in Cuba with contingency tables were obtained from the World Health Organisation and analysed. There were 3 736 718 male and 3 534 270 female births (1960-96). Births declined steadily over the entire period. The male-female ratio at birth remained relatively stable over the period 1960-1985 with significant sharp dips for the years 1966, 1980 and 1985. There was a sharp rise in M/F from 1966 to 1969, another rise after 1985, a steep drop to 1989, and then a sharp rise once more after 1993 (all p influencing M/F.

  12. Estrogenic exposure affects metamorphosis and alters sex ratios in the northern leopard frog (Rana pipiens): identifying critically vulnerable periods of development.

    Science.gov (United States)

    Hogan, Natacha S; Duarte, Paula; Wade, Michael G; Lean, David R S; Trudeau, Vance L

    2008-05-01

    During the transformation from larval tadpole to juvenile frog, there are critical periods of metamorphic development and sex differentiation that may be particularly sensitive to endocrine disruption. The aim of the present study was to identify sensitive developmental periods for estrogenic endocrine disruption in the northern leopard frog (Rana pipiens) using short, targeted exposures to the synthetic estrogen, ethinylestradiol (EE2). Post-hatch tadpoles (Gosner stage 27) were exposed over five distinct periods of metamorphosis: early (stage 27-30), mid (stage 30-36), early and mid (stage 27-36), late (stage 36-42), and the entire metamorphic period (chronic; stage 27-42). For each period, animals were sampled immediately following the EE2 exposure and at metamorphic climax (stage 42). The effects of EE2 on metamorphic development and sex differentiation were assessed through measures of length, weight, developmental stage, days to metamorphosis, sex ratios and incidence of gonadal intersex. Our results show that tadpoles exposed to EE2 during mid-metamorphosis were developmentally delayed immediately following exposure and took 2 weeks longer to reach metamorphic climax. In the unexposed groups, there was low proportion (0.15) of intersex tadpoles at stage 30 and gonads appeared to be morphologically distinct (male and female) in all individuals by stage 36. Tadpoles exposed early in development displayed a strong female-biased sex ratio compared to the controls. Moreover, these effects were also seen at metamorphic climax, approximately 2-3 months after the exposure period, demonstrating that transient early life-stage exposure to estrogen can induce effects on the reproductive organs that persist into the beginning of adult life-stages.

  13. Zeta Sperm Selection Improves Pregnancy Rate and Alters Sex Ratio in Male Factor Infertility Patients: A Double-Blind, Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Nasr Esfahani Mohammad Hossein

    2016-07-01

    Full Text Available Background Selection of sperm for intra-cytoplasmic sperm injection (ICSI is usually considered as the ultimate technique to alleviate male-factor infertility. In routine ICSI, selection is based on morphology and viability which does not necessarily preclude the chance injection of DNA-damaged or apoptotic sperm into the oocyte. Sperm with high negative surface electrical charge, named “Zeta potential”, are mature and more likely to have intact chromatin. In addition, X-bearing spermatozoa carry more negative charge. Therefore, we aimed to compare the clinical outcomes of Zeta procedure with routine sperm selection in infertile men candidate for ICSI. Materials and Methods From a total of 203 ICSI cycles studied, 101 cycles were allocated to density gradient centrifugation (DGC/Zeta group and the remaining 102 were included in the DGC group in this prospective study. Clinical outcomes were com- pared between the two groups. The ratios of Xand Y bearing sperm were assessed by fluorescence in situ hybridization (FISH and quantitative polymerase chain reaction (qPCR methods in 17 independent semen samples. Results In the present double-blind randomized clinical trial, a significant increase in top quality embryos and pregnancy rate were observed in DGC/Zeta group compared to DGC group. Moreover, sex ratio (XY/XX at birth significantly was lower in the DGC/Zeta group compared to DGC group despite similar ratio of X/Y bearings sper- matozoa following Zeta selection. Conclusion Zeta method not only improves the percentage of top embryo quality and pregnancy outcome but also alters the sex ratio compared to the conventional DGC method, despite no significant change in the ratio of Xand Ybearing sperm population (Registration number: IRCT201108047223N1.

  14. A cohort study of the association between secondary sex ratio and parental exposure to polybrominated biphenyl (PBB and polychlorinated biphenyl (PCB

    Directory of Open Access Journals (Sweden)

    Terrell Metrecia L

    2009-08-01

    Full Text Available Abstract Background Polybrominated biphenyl (PBB, a brominated flame retardant, was accidently mixed into animal feed in Michigan (1973–1974 resulting in human exposure through consumption of contaminated meat, milk and eggs. Beginning in 1976 individuals who consumed contaminated products were enrolled in the Michigan Long-Term PBB Study. This cohort presents a unique opportunity to study the association between parental exposures to PBB and offspring sex ratio. Methods We identified offspring of female PBB cohort participants (born 1975–1988 and obtained electronic birth records for those born in the state of Michigan. We linked this information to parental serum PBB and PCB concentrations collected at enrollment into the cohort. We modeled the odds of a male birth with generalized estimating equations accounting for the non-independence of siblings born to the same parents. We explored potential confounders: parental age and education at offspring's birth, parental body mass index at cohort enrollment, birth order, gestational age and year of offspring's birth. Results The overall proportion of male offspring among 865 live births to cohort mothers was 0.542. This was higher than the national male proportion of 0.514 (binomial test: p = 0.10. When both parents were in the cohort (n = 300, we found increased odds of a male birth with combined parents' enrollment PBB exposure ≥ the median concentrations (3 μg/L for mothers; 6 μg/L for fathers compared to combined parents' PBB exposure Conclusion This study adds to the body of literature on secondary sex ratio and exposure to environmental contaminants. In this population, combined parental exposure to PBBs or PCBs increased the odds of a male birth. Further research is needed to corroborate these findings and shed light on the biological mechanisms by which these types of chemicals may influence the secondary sex ratio.

  15. Effect of exposure time of pregnant females guppies, Poecilia reticulata Peters, in 17a-methyltestosterone solution on sex ratio of their offsprings

    OpenAIRE

    M. Zairin Junior; A. Yunianti; R.R.S.P.S. Dewi; Kusman Sumawidjaja

    2007-01-01

    ABSTRACTThis experiment was carried out to study the effect of female broodstocks immersion in 17amethyltestosterone (MT) solution on sex ratio of their offspring, Three-months old males and females were paired to mate in aquaria for four days.  Broodstocks were fed with frozen blood worm and water flea 2-3 tii-nes daily.  Twelve days after mating, female broodstock were treated by immersing in 2 mg/1 MT solution for 0. 6, 12, 24 and 48 hours.  Birthed guppy babies were collected and reared s...

  16. Estimating sex ratio biases in X-linked disorders: is there an excess of males in families with X-linked ichthyosis?

    Science.gov (United States)

    Gladstien, K; Shapiro, L J; Spence, M A

    1979-01-01

    We derive the conditional probabilities for estimating the sex ratio in families ascertained through affected males for the study of X-linked recessive diseases. These conditional probabilities correct for the fact that the probability that a family will be ascertained increases with the number of males in the family. Data from four published studies for X-linked ichthyosis vulgaris are analyzed, three having an excess of males and one having a highly statistically significant excess of males. It is not known if this difference in the two samples represents a biological difference between the two populations or an unrecognized ascertainment bias. PMID:517522

  17. Providing supplemental milk to piglets preweaning improves the growth but not survival of gilt progeny compared with sow progeny.

    Science.gov (United States)

    Miller, Y J; Collins, A M; Smits, R J; Thomson, P C; Holyoake, P K

    2012-12-01

    Gilt progeny have lighter weaning weights and greater postweaning medication and mortality rates compared with the progeny of older parity sows. Because weaning weight has been positively correlated with postweaning survival, this study aimed to determine whether the provision of supplemental milk preweaning could improve weaning weight and subsequent weights as well as postweaning survival of gilt progeny. The study was replicated in summer and winter as the effects of supplemental milk were expected to vary with season. The progeny of 80 gilts (parity 0) and 80 sows (parity 2 to 5) were allocated to both treatments: with or without supplemental milk in these 2 seasons with 5 sheds/season. Litter size was standardized (10 to 11 piglets) and each piglet was weighed at birth, d 21, weaning (4 wk), and 10 wk of age. Medications and mortalities were recorded both preweaning and postweaning. Pigs were housed within treatment groups postweaning, and ADFI and G:F were measured. Gilt progeny were 200 g lighter at birth in both replicates (P gilt and sow progeny by 800 g in summer (P gilts or sows (P > 0.05). Supplemental milk disappearance (the daily difference between the volume of milk provided and the residue left in the drinker) was greater in summer than winter (by 130 mL/piglet d(-1); P gilt progeny reached or exceeded that of nonsupplemented sow progeny. Gilt progeny had greater postweaning mortality (2.6%) and medication rates (6.2%) than sow progeny (1 and 2.2%, respectively; both P Gilt progeny also had less postweaning ADFI than sow progeny in winter (528 and 636 g, respectively; P 0.05). The hypothesis that supplemental milk provision did increase gilt progeny weaning weight was supported (especially in summer) but the supplementation had no effect on postweaning weights and survival. Efforts to improve gilt progeny postweaning growth and survival need to be aimed at improving health and immunity, not just weaning weight.

  18. Variations in the trabecular bone ratio of the maxilla according to sex, age, and region using micro-computed tomography in Koreans.

    Science.gov (United States)

    Kim, Sung-Tae; Won, Sung-Yoon; Kim, Sung-Hyun; Paik, Doo-Jin; Song, Wu-Chul; Koh, Ki-Seok; Kim, Hee-Jin; Hu, Kyung-Seok

    2011-03-01

    These cortical and trabecular bones maintain general bone structure. Bone mineral density (BMD) changes according to increasing age, sex, and teeth loss. From previous studies, the evaluation of BMD changes depended on conventional radiographic analysis. This study investigated the trabecular bone ratio (TBR) in maxillary bone samples based on data obtained by micro-computed tomography and estimated variations in BMD according to age, sex, and tooth loss. Thirty-eight specimens were scanned with micro-computed tomography and reconstructed three-dimensionally. Sections were made parallel to the axis of each tooth, and the TBR was measured. Data were statistically analyzed with 1-way analysis of variance and paired t-tests (α=0.05). The TBR differed significantly (P<0.05) in each tooth region in the dentate group but not in the edentulous group. The mean TBR was higher in men than in women. The TBR reduced more with increasing age in the dentate group than in the edentulous group. The TBR varies according to the presence of teeth, sex, and age in specific teeth regions.

  19. Radon progeny deposition in track-detection diffusion chambers

    CERN Document Server

    Pressyanov, D; Simeonov, G

    1999-01-01

    The sensitivity dependence for cylindrical diffusion chambers that are used for radon track-detection measurements on the deposition fraction of radon progeny atoms has been theoretically studied (sensitivity is the ratio: area track density/integrated sup 2 sup 2 sup 2 Rn activity concentration). Experimentally, the sensitivity values of both the metal- and plastic-made chambers were determined. Results indicate that the experimental sensitivity for metal chambers is in accordance with the theoretical model while a deviation of 15% is observed for plastic chambers. The uncertainty in the sensitivity values that is related to possible variations of the diffusion coefficient for sup 2 sup 1 sup 8 Po atoms was estimated to be less than 10%. (author)

  20. Fukushima simulation experiment: assessing the effects of chronic low-dose-rate internal 137Cs radiation exposure on litter size, sex ratio, and biokinetics in mice.

    Science.gov (United States)

    Nakajima, Hiroo; Yamaguchi, Yoshiaki; Yoshimura, Takashi; Fukumoto, Manabu; Todo, Takeshi

    2015-12-01

    To investigate the transgenerational effects of chronic low-dose-rate internal radiation exposure after the Fukushima Daiichi Nuclear Power Plant accident in Japan, 18 generations of mice were maintained in a radioisotope facility, with free access to drinking water containing (137)CsCl (0 and 100 Bq/ml). The (137)Cs distribution in the organs of the mice was measured after long-term ad libitum intake of the (137)CsCl water. The litter size and the sex ratio of the group ingesting the (137)Cs water were compared with those of the control group, for all 18 generations of mice. No significant difference was noted in the litter size or the sex ratio between the mice in the control group and those in the group ingesting the (137)Cs water. The fixed internal exposure doses were ∼160 Bq/g and 80 Bq/g in the muscles and other organs, respectively. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  1. Does the radiation from the interim storage in Gorleben affect the sex ratio of newborn children?; Beeinflusst die Strahlung aus dem Zwischenlager in Gorleben das Geschlechterverhaeltnis von Neugeborenen?

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann, H.W.; Schulze, H.; Wede, S. [GNS Gesellschaft fuer Nuklear-Service mbH, Gorleben (Germany); Mueller, S. [Studsvik GmbH, Pforzheim (Germany)

    2015-07-01

    In the professional world but especially in public, the question is discussed whether ionizing radiation from nuclear facilities has a significant impact on the secondary sex ratio of newborn children in the vicinity of the plants. This issue is of exceptional importance in the region around Gorleben, where the opposition to nuclear facilities and activities for decades is particularly strong. At the site borders of the interim storage facility (TBL-G) of GNS the effective individual dose is about 0.2 mSv per year, mainly caused by neutron irradiation from 108 casks with high-level radioactive waste from reprocessing. In the surrounding villages there is no radiation measurable. Statistical studies allegedly have shown evidence that in some villages in the area and during certain periods, proportionately fewer girls were born in comparison to the average for the Federal Republic of Germany. Based on these purely statistical results henceforward was also alleged that neutron-induced secondary effects such as activation or secondary gamma radiation would be responsible for it. Monte Carlo calculations and special measurements yielded values of the dose at the plant border for activation products less than E-04 mSv/a and for secondary gamma radiation of about E-03 mSv/a. These results indicate that the ionizing radiation from the Gorleben interim storage facility cannot be held accountable for shifts of the secondary sex ratio.

  2. Sex ratio at birth: scenario from normal- and high-level natural radiation areas of Kerala coast in south-west India

    Energy Technology Data Exchange (ETDEWEB)

    Koya, P.K.M.; Jaikrishan, G.; Sudheer, K.R. [Bhabha Atomic Research Centre, Low Level Radiation Research Laboratory, Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Science Group, Kollam (India); Madhusoodhanan, M. [Victoria Hospital, Department of Paediatrics, Kollam (India); Jagadeesan, C.K. [Directorate of Health Services, Thiruvananthapuram (India); Das, Birajalaxmi [Bhabha Atomic Research Centre, Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Science Group, Mumbai (India); Andrews, V.J.

    2015-11-15

    Newborns were monitored for congenital malformations in four government hospitals located in high-level (ambient dose >1.5 mGy/year) and normal-level (≤1.5 mGy/year) natural radiation areas of Kerala, India, from August 1995 to December 2012. Sex ratio at birth (SRB) among live singleton newborns and among previous children, if any, of their mothers without history of any abortion, stillbirth or twins is reported here. In the absence of environmental stress or selective abortion of females, global average of SRB is about 1050 males to 1000 females. A total of 151,478 singleton, 1031 twins, 12 triplets and 1 quadruplet deliveries were monitored during the study period. Sex ratio among live singleton newborns was 1046 males (95 % CI 1036-1057) for 1000 females (77,153 males:73,730 females) and was comparable to the global average. It was similar in high-level and normal-level radiation areas of Kerala with SRB of 1050 and 1041, respectively. It was consistently more than 1000 and had no association with background radiation levels, maternal and paternal age at birth, parental age difference, gravida status, ethnicity, consanguinity or year of birth. Analysis of SRB of the children of 139,556 women whose reproductive histories were available suggested that couples having male child were likely to opt for more children and this, together with enhanced rate of males at all birth order, was skewing the overall SRB in favour of male children. Though preference for male child was apparent, extreme steps of sex-selective abortion or infanticide were not prevalent. (orig.)

  3. Sex ratio at birth: scenario from normal- and high-level natural radiation areas of Kerala coast in south-west India.

    Science.gov (United States)

    Koya, P K M; Jaikrishan, G; Sudheer, K R; Andrews, V J; Madhusoodhanan, M; Jagadeesan, C K; Das, Birajalaxmi

    2015-11-01

    Newborns were monitored for congenital malformations in four government hospitals located in high-level (ambient dose >1.5 mGy/year) and normal-level (≤ 1.5 mGy/year) natural radiation areas of Kerala, India, from August 1995 to December 2012. Sex ratio at birth (SRB) among live singleton newborns and among previous children, if any, of their mothers without history of any abortion, stillbirth or twins is reported here. In the absence of environmental stress or selective abortion of females, global average of SRB is about 1050 males to 1000 females. A total of 151,478 singleton, 1031 twins, 12 triplets and 1 quadruplet deliveries were monitored during the study period. Sex ratio among live singleton newborns was 1046 males (95 % CI 1036-1057) for 1000 females (77,153 males:73,730 females) and was comparable to the global average. It was similar in high-level and normal-level radiation areas of Kerala with SRB of 1050 and 1041, respectively. It was consistently more than 1000 and had no association with background radiation levels, maternal and paternal age at birth, parental age difference, gravida status, ethnicity, consanguinity or year of birth. Analysis of SRB of the children of 139,556 women whose reproductive histories were available suggested that couples having male child were likely to opt for more children and this, together with enhanced rate of males at all birth order, was skewing the overall SRB in favour of male children. Though preference for male child was apparent, extreme steps of sex-selective abortion or infanticide were not prevalent.

  4. Associations of cortisol/testosterone and cortisol/sex hormone-binding globulin ratios with atherosclerosis in middle-age women.

    Science.gov (United States)

    Lee, Ju-Mi; Colangelo, Laura A; Schwartz, Joseph E; Yano, Yuichiro; Siscovick, David S; Seeman, Teresa; Schreiner, Pamela J; Liu, Kiang J; Lloyd-Jones, Donald M; Greenland, Philip

    2016-05-01

    The cortisol/testosterone (C/T) ratio has been hypothesized to be a better predictor of atherosclerosis than cortisol alone. No study has assessed whether the C/T and C/sex hormone-binding globulin (SHBG) ratios are associated with atherosclerosis in a U.S. population sample. This substudy included 367 women who had both cortisol from year 15 and testosterone and SHBG at year 16 of the Coronary Artery Risk Development in Young Adults study, an ongoing observational cohort in the United States. Of these, intima-media thickness (IMT) was available at follow-up year 20 in 339 (n = 332 with measurement at carotid bulb), and 303 were free of prevalent coronary artery calcium (CAC) at year 15. Area under the curve (AUC) of salivary cortisol was available in 302 individuals. Ratios of AUCs of cortisol to total testosterone, free testosterone, and SHBG were categorized into tertiles. Associations with CAC and IMT were assessed by regression models adjusted for age, race, body mass index, systolic blood pressure, menopause, oral contraceptive use, diabetes, alcohol, and smoking. Only the highest tertile of the AUC/free testosterone ratio was positively associated with carotid bulb IMT (β = 0.088, P = 0.006). This tertile was also positively associated with new onset CAC between year 15 and 25 (OR 3.45, 95% CI 1.18-10.06). Tertiles of cortisol or testosterone alone were not associated with new onset CAC. AUC/Free testosterone ratio may be more associated with atherosclerosis in women than either indicator alone. The ratio may serve as a suitable biomarker of cortisol-linked stress. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  5. Complementary Sex Determination in the Parasitic Wasp Diachasmimorpha longicaudata

    Science.gov (United States)

    Carabajal Paladino, Leonela; Muntaabski, Irina; Lanzavecchia, Silvia; Le Bagousse-Pinguet, Yoann; Viscarret, Mariana; Juri, Marianela; Fueyo-Sánchez, Luciana; Papeschi, Alba; Cladera, Jorge; Bressa, María José

    2015-01-01

    We studied the sex determination in Diachasmimorpha longicaudata, a parasitoid braconid wasp widely used as biological control agent of fruit pest tephritid flies. We tested the complementary sex determination hypothesis (CSD) known in at least 60 species of Hymenoptera. According to CSD, male or female development depends on the allelic composition of one sex locus (single-locus CSD) or multiple sex loci (multiple-locus CSD). Hemizygote individuals are normal haploid males, and heterozygotes for at least one sex locus are normal diploid females, but homozygotes for all the sex loci are diploid males. In order to force the occurrence of diploid males in D. longicaudata, we established highly inbred lines and examined their offspring using chromosome counting, flow cytometry, and sex ratio analysis. We found that when mother-son crosses were studied, this wasp produced about 20% of diploid males out of the total male progeny. Our results suggest that this parasitoid may represent the second genus with multiple-locus CSD in Hymenoptera. Knowledge about the sex determination system in D. longicaudata is relevant for the improvement of mass rearing protocols of this species. This information also provides the necessary background for further investigations on the underlying molecular mechanisms of sex determination in this species, and a better insight into the evolution of this pathway in Hymenoptera in particular and insects in general. PMID:25789748

  6. ARTICLE - Inbreeding depression in castor bean (Ricinus communis L. progenies

    Directory of Open Access Journals (Sweden)

    Milton Krieger

    2012-12-01

    Full Text Available The purpose of this study was to investigate inbreeding depression (DE in castor bean. From a population derived from the Guarani cultivar, 60 mother plants were sampled. Three types of progenies were obtained from each one: from self-pollination (AU, from crosses (CR and from open pollination (PL. Grain yield of the progenies was evaluated in two locations. There was a strong interaction of progenies x locations, which led to obtaining estimates within each location. Broad variation was observed in inbreeding depression, with mean values of 6.7% and 13.4%, comparing AU progenies with PL progenies. It was observed that the population has high potential for selecting promising inbred lines. The frequency of mother plants generating progenies with simultaneous high general combination capacity and low inbreeding depression was low. Recurrent selection will increase the occurrence of parent plants associating these two properties, which is necessary for obtaining superior synthetic varieties.

  7. ACC oxidase and miRNA 159a, and their involvement in fresh fruit bunch yield (FFB) via sex ratio determination in oil palm.

    Science.gov (United States)

    Somyong, Suthasinee; Poopear, Supannee; Sunner, Supreet Kaur; Wanlayaporn, Kitti; Jomchai, Nukoon; Yoocha, Thippawan; Ukoskit, Kittipat; Tangphatsornruang, Sithichoke; Tragoonrung, Somvong

    2016-06-01

    Oil palm (Elaeis guineesis Jacq.) is the most productive oil-bearing crop, yielding more oil per area than any other oil-bearing crops. However, there are still efforts to improve oil palm yield, in order to serve consumer and manufacturer demand. Oil palm produces female and male inflorescences in an alternating cycle. So, high sex ratio (SR), the ratio of female inflorescences to the total inflorescences, is a favorable trait in term of increasing yields in oil palm. This study aims to understand the genetic control for SR related traits, such as fresh fruit bunch yield (FFB), by characterizing genes at FFB quantitative trait loci (QTLs) on linkage 10 (chromosome 6) and linkage 15 (chromosome 10). Published oil palm sequences at the FFB QTLs were used to develop gene-based and simple sequence repeat (SSR) markers. We used the multiple QTL analysis model (MQM) to characterize the relationship of new markers with the SR traits in the oil palm population. The RNA expression of the most linked QTL genes was also evaluated in various tissues of oil palm. We identified EgACCO1 (encoding aminocyclopropane carboxylate (ACC) oxidase) at chromosome 10 and EgmiR159a (microRNA 159a) at chromosome 6 to be the most linked QTL genes or determinants for FFB yield and/or female inflorescence number with a phenotype variance explained (PVE) from 10.4 to 15 % and suggest that these play the important roles in sex determination and differentiation in oil palm. The strongest expression of EgACCO1 and the predicted precursor of EgmiR159a was found in ovaries and, to a lesser extent, fruit development. In addition, highly normalized expression of EgmiR159a was found in female flowers. In summary, the QTL analysis and the RNA expression reveal that EgACCO1 and EgmiR159a are the potential genetic factors involved in female flower determination and hence would affect yield in oil palm. However, to clarify how these genetic factors regulate female flower determination, more investigation

  8. [Are there Sex Differences Regarding Ski Length to Height Ratio, Ski Length to Weight Ratio, Sidecut Radius and Ski Boot Sole Abrasion among ACL Injured Male and Female Skiers?

    Science.gov (United States)

    Posch, Markus; Ruedl, Gerhard; Tecklenburg, Katja; Helle, Kenneth; Schranz, Alois; Burtscher, Martin

    2017-06-01

    Introduction  Female skiers suffer from knee injuries twice as much as male skiers, and the risk of an injury to the anterior cruciate ligament (ACL) is three times greater among females compared to males. The sex-specific ACL injury risk depends on internal (e. g. age, skiing skills, fitness level) and external (e. g. slope and weather conditions, ski equipment) factors. However, it is not clear whether male and female recreational skiers with an ACL injury differ regarding the sidecut radius and ski boot sole abrasion. Method  This questionnaire-based study was conducted in the winter seasons 2014/15 and 2015/16. During those periods, data of ACL-injured skiers were collected at an Austrian ski clinic. The questionnaire included information about demographics, skiing skills, type of fall, binding release, and injury diagnosis. Furthermore, the ski length and sidecut radius were notated from the ski, and abrasion of ski boot sole was measured at the toe and heel piece of the ski boot using a caliper. Results  In total 164 ACL-injured skiers (67 % females) with a mean age of 41.7 ± 11.5 years were recorded. Males used significantly longer skies compared to females (168.3 ± 6.6 vs. 157.5 ± 5.9 cm, p ski length to height ratio (94.0 ± 3.4 vs. 94.1 ± 3.3 %) showed no significant difference between the two sexes. The ski length to weight ratio was significantly different between females and males (2.5 ± 0.3 vs. 2.0 ± 0.2 cm/kg). The sidecut radius (13.5 ± 1.4 vs. 15.6 ± 2.6 m, p ski boot soles, neither at the toe piece (5.4 ± 1.2 vs. 5.5 ± 1.1 mm) nor at the heel piece (6.0 ± 1.7 vs. 6.0 ± 1.6 mm) between females and males. For both sexes the most common type of fall was the forward fall with body rotation (approximately 59 %). Failure of binding release was significantly more often reported by females compared to males (86 vs. 44 %, p ski length to weight ratio, and the

  9. Sex determination in crayfish: are intersex Cherax quadricarinatus (Decapoda, Parastacidae) genetically females?

    Science.gov (United States)

    Parnes, S; Khalaila, I; Hulata, G; Sagi, A

    2003-10-01

    In the Australian red-claw crayfish Cherax quadricarinatus (von Martens) (Decapoda, Parastacidae), a gonochoristic species, seven different combinations of intersex individuals (with both male and female genital openings) have been described. However, to date, the genetic basis for this phenomenon has not been investigated. This study was designed to test a simple chromosome-based sex-determination model for C. quadricarinatus that assumes the male to be the homogametic (ZZ) sex. According to our model, intersex individuals that are functionally males are genetically females (WZ). Individual crosses were performed between intersex and female crayfish, with control crosses being performed between normal males and females. The control crosses yielded, in most cases, the expected 1:1 sex ratio in the F1 progeny. Crosses between intersex individuals and females yielded a 1:3 (male:female) sex ratio in most crosses. According to our hypothesis, one-third of the females produced in a cross of a female with an intersex animal should be WW females. The hypothesis was tested by crossing normal males with F1 females, which were progeny of intersex fathers. These crosses yielded almost 100% females, a finding that conforms to the above-suggested sex determination model for C. quadricarinatus and the female WZ genotype of intersex individuals.

  10. Impact of consanguineous marriages and degrees of inbreeding on fertility, child mortality, secondary sex ratio, selection intensity, and genetic load: a cross-sectional study from Northern India.

    Science.gov (United States)

    Fareed, Mohd; Kaisar Ahmad, Mir; Azeem Anwar, Malik; Afzal, Mohammad

    2017-01-01

    The aim of our study was to understand the relationship between consanguineous marriages and reproductive outcomes. A total of 999 families were recruited from five Muslim populations of Jammu region. Family pedigrees were drawn to access the family history and inbreeding status in terms of coefficient of inbreeding (F). Fertility, mortality, secondary sex ratio, selection intensity, and lethal equivalents were measured using standard methods. The significant differences for gross fertility was found to be higher among inbred groups as compared to the unrelated families (P child mortality rates (i.e., U5MR and U18MR) have presented a persuasive increase with an upsurge in the homozygosity level. The mortality rate was found to be maximum among families with the highest value of coefficient of inbreeding (F). The selection intensity (SI) also showed inflations among families with respect to their increasing inbreeding coefficients. The greater values of lethal equivalents per gamete (LEs/gamete) were observed for autosomal inheritance in comparison with sex-linked inheritance. Our conclusive assessment brings out the deleterious consequence of consanguineous marriages on reproductive outcomes.

  11. Predicting the variation in Echinogammarus marinus at its southernmost limits under global warming scenarios: can the sex-ratio make a difference?

    Science.gov (United States)

    Guerra, Alexandra; Leite, Nuno; Marques, João Carlos; Ford, Alex T; Martins, Irene

    2014-01-01

    Understanding the environmental parameters that constrain the distribution of a species at its latitudinal extremes is critical for predicting how ecosystems react to climate change. Our first aim was to predict the variation in the amphipod populations of Echinogammarus marinus from the southernmost limit of its distribution under global warming scenarios. Our second aim was to test whether sex-ratio fluctuations - a mechanism frequently displayed by amphipods - respond to the variations in populations under altered climate conditions. To achieve these aims, scenarios were run with a validated model of E. marinus populations. Simulations were divided into: phase I - simulation of the effect of climate change on amphipod populations, and phase II - simulation of the effect of climate change on populations with male and female proportions. In both phases, temperature (T), salinity (S) and temperature and salinity (T-S) were tested. Results showed that E. marinus populations are highly sensitive to increases in temperature (>2 °C), which has adverse effects on amphipod recruitment and growth. Results from the climate change scenarios coupled with the sex-ratio fluctuations depended largely on the degree of female bias within population. Temperature increase of 2 °C had less impact on female-biased populations, particularly when conjugated with increases in salinity. Male-biased populations were highly sensitive to any variation in temperature and/or salinity; these populations exhibited a long-term decline in density. Simulations in which temperature increased more than 4 °C led to a continuous decline in the E. marinus population. According to this work, E. marinus populations at their southernmost limit are vulnerable to global warming. We anticipate that in Europe, temperature increases of 2 °C will incite a withdrawal of the population of 5°N from the amphipod species located at southernmost geographical borders. This effect is discussed in relation to the

  12. FOLIAR NUTRIENT CONTENTS AND FRUIT YIELD IN CUSTARD APPLE PROGENIES

    Directory of Open Access Journals (Sweden)

    Paulo Sérgio Lima e Silva

    2009-01-01

    Full Text Available Foliar nutrient contents are evaluated in several fruit trees with many objectives. Leaf analysis constitutes a way of evaluating the nutritional requirements of crops. Due to the positive impact that fertilizers have on crop yields, researchers frequently try to evaluate the correlations between yield and foliar nutrient contents. This work's objective was to present fruit yields from the 4th to the 6th cropping seasons, evaluate foliar nutrient contents (on the 5th cropping season, and estimate the correlations between these two groups of traits for 20 half-sibling custard apple tree progenies. The progenies were evaluated in a random block design with five replicates and four plants per plot. One hundred leaves were collected from the middle third of the canopy (in height of each of four plants in each plot. The leaves were collected haphazardly, i.e., in a random manner, but without using a drawing mechanism. In the analysis of variance, the nutrient concentrations in the leaves from plants of each plot were represented by the average of four plants in the plot. Fruit yield in the various progenies did not depend on cropping season; progeny A4 was the most productive. No Spearman correlation was found between leaf nutrient concentrations and fruit yield. Increased nutrient concentrations in the leaves were progeny-dependent, i.e., with regard to Na (progenies FE5 and JG1, Ca (progeny A4, Mg (progeny SM7, N (progeny A3, P (progeny M, and K contents (progeny JG3. Spearman's correlation was negative between Na-Mg, Na-Ca, and Mg-P contents, and positive between Mg-Ca and N-K contents.

  13. Estimation of human dose to radon progeny

    Energy Technology Data Exchange (ETDEWEB)

    Shimo, Michikuni [Gifu Coll. of Medical Technology, Sekiichi, Gifu (Japan)

    1996-12-01

    The aim of the paper is the estimation of the effective dose due to radon progeny for Japanese population. The estimation was performed by a modified UNSCEAR equation. The equation was needed the radon concentration annual occupancy time and the tidal volume on Japanese people and the dose conversion coefficient are needed. Furthermore, not only these figures but also unattached fraction and aerosol distribution data obtained in Japan and the factor related to the Japanese living style were used in the calculation. We used following figures as representative value in Japan; radon concentration: 13(6 - 25) Bq/m{sup 3} indoors and 6.7(3.5 - 13) Bq/m{sup 3} outdoors; the equilibrium factor: 0.45(0.35 - 0.57) indoors and 0.70(0.50 - 0.90) outdoors; the occupancy factor: 0.87 indoors, 0.09 outdoors and 0.04 in vehicle for male and 0.91 indoors, 0.06 outdoors and 0.03 in vehicle for female; the tidal volume: 7,000 (4,000 - 8,000) m{sup 3} for male, 6,200 (3,500 - 7,500) m{sup 3} for female. The effective doses due to radon progeny were estimated to be 0.45 mSv/y for male and 0.40 mSv/y for female, and the variance was -80 - +130%. These values were 1/2 - 1/3 as small as values shown by UNSCEAR 1993 Report and estimated by ICRP Publication 65. (author)

  14. Applications of a silicon photodiode detector for radon progeny measurements

    CERN Document Server

    Voytchev, M; Chambaudet, A; Georgiev, G; Iovtchev, M

    1999-01-01

    An application of our developed silicon photodiode detector for radon progeny measurements is presented in this paper. It was determined the deposition velocity for free (3.6+-0.7)x10 sup - sup 3 m s sup - sup 1 and attached (1.0+-0.5)x10 sup - sup 5 m s sup - sup 1 fraction of short living radon progeny.

  15. Modelling radon progeny concentration variations in thermal spas.

    Science.gov (United States)

    Nikolopoulos, Dimitrios; Vogiannis, Efstratios

    2007-02-01

    Radon and its short-lived progenies (218Po, 214Pb, 214Bi and 214Po) are well known radioactive indoor pollutants identified as the major radiation burden component of the thermal spa users. Monitoring of short-lived progeny concentration is of great importance for short-term dose estimations both for bathers and working personnel. A prediction model of the short-lived progeny concentration variations was developed and applied on published data of the thermal spas of Lesvos Island. The physical procedures involved were modeled in a set of differential equations describing radon progeny concentration variations on the basis of radon measurements. Published daughter data were fitted on model predictions adjusting non-measured parameters, e.g. attachment and deposition rate constants for attached and unattached progenies. Attachment rate constants were estimated between 50 and 200 h-1 while the deposition rate constants between 0.25 and 5 h-1 for attached progenies and 0.5 and 170 h-1 for the unattached ones. In addition, unattached 218Po, 214Pb and 214Bi progenies were found to be shifted forward in respect to radon approximately 0.001 h, 0.05 h and 0.40 h respectively, while attached 218Po, 214Pb and 214Bi progenies 0.05 h, 0.45 h and 0.65 h respectively.

  16. Maternal investment in relation to sex ratio and offspring number in a small mammal - a case for Trivers and Willard theory?

    Science.gov (United States)

    Koskela, Esa; Mappes, Tapio; Niskanen, Tuuli; Rutkowska, Joanna

    2009-09-01

    1. Optimal parental sex allocation depends on the balance between the costs of investing into sons vs. daughters and the benefits calculated as fitness returns. The outcome of this equation varies with the life history of the species, as well as the state of the individual and the quality of the environment. 2. We studied maternal allocation and subsequent fecundity costs of bank voles, Myodes glareolus, by manipulating both the postnatal sex ratio (all-male/all-female litters) and the quality of rearing environment (through manipulation of litter size by -2/+2 pups) of their offspring in a laboratory setting. 3. We found that mothers clearly biased their allocation to female rather than male offspring regardless of their own body condition. Male pups had a significantly lower growth rate than female pups, so that at weaning, males from enlarged litters were the smallest. Mothers produced more milk for female litters and also defended them more intensively than male offspring. 4. The results agree with the predictions based on the bank vole life history: there will be selection for greater investment in daughters rather than sons, as a larger size seems to be more influencial for female reproductive success in this species. Our finding could be a general rule in highly polygynous, but weakly dimorphic small mammals where females are territorial. 5. The results disagree with the narrow sense Trivers & Willard hypothesis, which states that in polygynous mammals that show higher variation in male than in female reproductive success, high-quality mothers are expected to invest more in sons than in daughters.

  17. Effect of exposure time of pregnant females guppies, Poecilia reticulata Peters, in 17a-methyltestosterone solution on sex ratio of their offsprings

    Directory of Open Access Journals (Sweden)

    M. Zairin Junior

    2007-05-01

    Full Text Available ABSTRACTThis experiment was carried out to study the effect of female broodstocks immersion in 17amethyltestosterone (MT solution on sex ratio of their offspring, Three-months old males and females were paired to mate in aquaria for four days.  Broodstocks were fed with frozen blood worm and water flea 2-3 tii-nes daily.  Twelve days after mating, female broodstock were treated by immersing in 2 mg/1 MT solution for 0. 6, 12, 24 and 48 hours.  Birthed guppy babies were collected and reared separately from their parents.  During the rearing period, the babies were fed with artemia nauplius and silkworm until identification for male and female.  Percentage of female offspring in control group were higher than those of male.  Exposure of pregnant females to MT solution for 0, 6, 12, 24, and 48 hours resulted in 42, 1'/o, 51%, 84,6%, 1 00%, dan 100% of males offspring, respectively.  The best result was obtained from 24 hours treatment.  Longer treatment duration tend to shorten time interval between treatment and birth. Key words :  Guppy, 17(x-methyltestosterone, exposure time, broodstock immersion, sex ratio   ABSTRAK Penefitian ini bertuiuan untuk mengetahui pengaruh lama waktu perendaman induk di dalam larutan hormon 17a-metiltestosteron (MT terhadap nisbah kelamin ikan gapi.  Induk Ikan gapi berumur tiga bulan dikawinkan berpasangan di dalam akuarium selama empat hari Induk diberi pakan cuk merah beku dan kutu air dengan frekuensi 2-3 kali sehari.  Dua belas hari setelah masa perkawinan, induk betina diberi perlakuan berupa perendaman di dalam larutan MT 2 mg/1 selama 0 (kontrol, 6, 12, 24, dan 48 jam.  Anak-anak ikan gapi yang baru lahir dipelihara terpisah dari induknya.  Selama masa pemeliharaan, anak ikan gapi diberi pakan nauplius artemia dan cacing rambut.  Pemeliharaan berlangsung sampai jenis kelamin anak ikan gapi dapat diidentifikasi.  Persentase anak ikan gapi betina pada semua ulangan kontrol lebih tinggi daripada

  18. Sex, age, pubertal development and use of oral contraceptives in relation to serum concentrations of DHEA, DHEAS, 17α-hydroxyprogesterone, Δ4-androstenedione, testosterone and their ratios in children, adolescents and young adults

    DEFF Research Database (Denmark)

    Søeborg, Tue; Frederiksen, Hanne; Mouritsen, Annette

    2014-01-01

    serum samples from healthy children, adolescents and young adults was evaluated. Samples were analyzed by Turboflow-LC-MS/MS. Sex hormone-binding globulin was analyzed by immunoassay. All steroid metabolite concentrations were positively associated with age and pubertal development in both sexes......The influence of sex, age, pubertal development and oral contraceptives on dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), 17α-hydroxyprogesterone (17-OHP), Δ4-androstenedione (Adione), testosterone (T), calculated free testosterone (fT), free androgen index (FAI) and selected ratios in 1798...... to sex, age and pubertal development. Use of oral contraceptives strongly influences adrenal steroidogenesis and should be considered when diagnosing and monitoring treatment of patients with disorders of sex development....

  19. RELATIVE PERFORMANCE OF SELFED AND OUTCROSSED PROGENY IN IMPATIENS CAPENSIS.

    Science.gov (United States)

    Mitchell-Olds, Thomas; Waller, Donald M

    1985-05-01

    This study compares survival and growth of progeny derived from chasmogamous (CH) and cleistogamous (CL) flowers in Impatiens capensis, a forest annual. When progeny were grown in the field, CH seeds had significantly higher survival rates over winter (64% versus 56%), and the survival advantage of outcrossed progeny was not attributable to seed weight differences. No differences in seedling growth were detected. Greenhouse comparisons revealed no difference in seed survival but a 30% growth advantage to CH seedlings. We found no changes in developmental homeostasis of three leaf shape characters between inbred and outbred progeny, nor was there any difference in variability within CH and CL families. The outcrossing advantage observed in these experiments could not have been caused by avoidance of sib competition. Theory predicts that self-pollinated progenies may be more variable than outcrossed progenies if rare, recessive alleles are important contributors to genetic variances. Electrophoretic markers indicate that progeny derived from CH flowers are predominantly outcrossed (at least 54-97%). © 1985 The Society for the Study of Evolution.

  20. Growth, fecundity and sex ratio of adult whaleworm (Anisakis simplex; Nematoda, Ascaridoidea, Anisakidae) in three whale species from the North-East Atlantic.

    Science.gov (United States)

    Ugland, Karl Inne; Strømnes, Einar; Berland, Bjørn; Aspholm, Paul Eric

    2004-04-01

    The growth rate, fecundity, and sex ratio of Anisakis simplex in minke whales (Balaenoptera acutorostrata), porpoises (Phocoena phocoena) and long-finned pilot whales (Globicephala melas) was studied on the basis of material from the North Atlantic. A total of 8,135 mature A. simplex were collected from 24 minke whales, 11 porpoises and eight pilot whales. For both males and females, the prevalence was 100% for all three host species, with a mean intensity of 1,727, 262 and 139, respectively. The mean body length of adult female A. simplex was 126 mm in minke whales, 71 mm in the porpoises and 73 mm in pilot whales; and for males the averages were, respectively, 106 mm, 57 mm and 68 mm. Eggs from the uteri of 32 females of length 87-176 mm collected in minke whale stomachs were counted in a Fuchs-Rosenthal chamber. Total egg production was measured in 14 females cultivated at sea. The female growth period was estimated to be 30-60 days, and apparently all eggs were shed during the last week of life. A female of size 150 mm produces approximately 1.5 million eggs. In the cultivation experiment, about 85% of the total egg production was shed during the first 3 days after spawning started.

  1. The Sex Ratio at Birth for 5,338,853 Deliveries in China from 2012 to 2015: A Facility-Based Study.

    Directory of Open Access Journals (Sweden)

    Yan Huang

    Full Text Available The accuracy of a population-based sex ratio at birth (SRB in China has long been questioned. To depict a more accurate profile, the present study used data from a national surveillance system for health facility births to explore the characteristics of SRB in China.Data from China's National Maternal Near Miss Surveillance System between 2012 and 2015 were used. We restricted the analysis to live births of ≥28 completed gestational weeks or ≥1000 g birth weight. The strength of association between obstetric characteristics and SRB was examined using logistic regression, taking into account the sampling strategy and clustering of births within health facilities.There were 2,785,513 boys and 2,549,269 girls born alive between 2012 and 2015 in 441 health facilities. The SRB was 111.04 in 2012, 110.16 in 2013, 108.79 in 2014, and 109.53 in 2015. The SRB was high in the eastern region, especially in rural areas. The SRBs increased with mother's age and decreased with mother's education. The SRB in women who were pregnant for the first time was 104.30. The SRB in primipara was normal (104.35, but it was extremely high in non-primipara, especially for women with three or more parities (141.76; only 5.26% of live births fell within this group. The SRBs increased significantly by the number of parities, especially in the rural areas of the central region. After adjustment for sociodemographic factors, women with three or more parities were 1.39 (95% CI 1.34, 1.43 times more likely to give birth to a boy compared with primiparae who were pregnant for the first time.Our analysis suggests that the SRB was lower than what was reported officially but higher than normal. The government should keep strengthening supervision to prevent sex-selection, especially in the wake of the two-child policy implemented in 2015.

  2. Genetic Variation Among Open-Pollinated Progeny of Eastern Cottonwood

    Science.gov (United States)

    R. E. Farmer

    1970-01-01

    Improvement programs in eastern cottonwood (Populus deltoides Bartr.) are most frequently designed to produce genetically superior clones for direct commercial use. This paper describes a progeny test to assess genetic variability on which selection might be based.

  3. Mapping the sex determination locus in the Atlantic halibut (Hippoglossus hippoglossus) using RAD sequencing.

    Science.gov (United States)

    Palaiokostas, Christos; Bekaert, Michaël; Davie, Andrew; Cowan, Mairi E; Oral, Münevver; Taggart, John B; Gharbi, Karim; McAndrew, Brendan J; Penman, David J; Migaud, Hervé

    2013-08-20

    Atlantic halibut (Hippoglossus hippoglossus) is a high-value, niche market species for cold-water marine aquaculture. Production of monosex female stocks is desirable in commercial production since females grow faster and mature later than males. Understanding the sex determination mechanism and developing sex-associated markers will shorten the time for the development of monosex female production, thus decreasing the costs of farming. Halibut juveniles were masculinised with 17 α-methyldihydrotestosterone (MDHT) and grown to maturity. Progeny groups from four treated males were reared and sexed. Two of these groups (n = 26 and 70) consisted of only females, while the other two (n = 30 and 71) contained balanced sex ratios (50% and 48% females respectively). DNA from parents and offspring from the two mixed-sex families were used as a template for Restriction-site Associated DNA (RAD) sequencing. The 648 million raw reads produced 90,105 unique RAD-tags. A linkage map was constructed based on 5703 Single Nucleotide Polymorphism (SNP) markers and 7 microsatellites consisting of 24 linkage groups, which corresponds to the number of chromosome pairs in this species. A major sex determining locus was mapped to linkage group 13 in both families. Assays for 10 SNPs with significant association with phenotypic sex were tested in both population data and in 3 additional families. Using a variety of machine-learning algorithms 97% correct classification could be obtained with the 3% of errors being phenotypic males predicted to be females. Altogether our findings support the hypothesis that the Atlantic halibut has an XX/XY sex determination system. Assays are described for sex-associated DNA markers developed from the RAD sequencing analysis to fast track progeny testing and implement monosex female halibut production for an immediate improvement in productivity. These should also help to speed up the inclusion of neomales derived from many families to maintain a

  4. IDENTIFIKASI GEN AROMA PADA PROGENI-PROGENI BACKCROSS ANTARA VARIETAS CIHERANG DENGAN PANDAN WANGI

    Directory of Open Access Journals (Sweden)

    Djarot Sasongko Hami Seno

    2011-08-01

    Full Text Available Marker-assisted PCR has been considered as the most potential method for fragrant selection. RM223 is the only suitable marker to identify mutated badh2 gene of Pandan Wangi. This research applies RM223-assisted PCR in the introgression of fragrant gene (mutated badh2 of Pandan Wangi variety, to engineer non-transgenic fragrant variety with good agronomic traits as those of Ciherang. Gene introduction was carried out through site-directed crossing; Pandan Wangi was crossed and backcrossed to Ciherang until heterozygot BC5F1, followed by selfing to obtain homozygot BC5F2. RM223-assisted selection was conducted in each cross and backcross generation. RM223 was able to identify native, mutated and heterozygot badh2 of Ciherang, Pandan Wangi, and their cross/backcross progenies, respectively. Therefore, the introgression of mutated badh2 within progenies were observed, as well as the statues of badh2 gene (native/mutated and alleles (homozygot/heterozygot. Further backcross and selfing to obtain BC5F2 is in progress

  5. Genotypic value in hybrid progenies of Panicum maximum Jacq.

    Directory of Open Access Journals (Sweden)

    Thiago Gomes dos Santos Braz

    Full Text Available ABSTRACT: Genetic breeding of forage plants has increasingly contributed to the release of more productive plants. In this regard, evaluating the genotypic value is essential when aiming to rank genotypes based on the mean free of environmental factors. Therefore, this study aimed to predict the genotypic value of agronomic and nutritive value characters of three progenies of Panicum maximum. Hybrids were evaluated in a clonal test in an incomplete-randomized design with three treatments (progenies 1, 2, and 3 and two replications (clones. Six harvests were performed at 25cm from the ground level throughout one year. Progeny 2 provided better results for total and leaf dry mass yield, regrowth, and height, and lower incidence of leaf spot. Progenies 1 and 3 had a better response for qualitative characters such as higher crude protein and digestibility and lower lignin and fiber content. Hybrid progenies of P. maximum have forage characters of interest for breeding, and when using ‘Mombaça’ grass as parents, the progeny stands out for leaf production and resistance to leaf spot and for ‘Tanzania’ grass as parent has resulted in better forage quality.

  6. Habitat use, size structure and sex ratio of the spot-legged turtle, Rhinoclemmys punctularia punctularia (Testudines: Geoemydidae, in Algodoal-Maiandeua Island, Pará, Brazil

    Directory of Open Access Journals (Sweden)

    Manoela Wariss

    2012-03-01

    Full Text Available Rhinoclemmys punctularia punctularia is a semi-aquatic chelonian found in Northern South America. We analyzed the habitat use, size structure and sex ratio of the species on Algodoal-Maiandeua Island, a protected area on the Northeastern coast of the Brazilian state of Pará. Four distinct habitats (coastal plain lake, flooded forest “igapó”, interdunal lakes, and tidal channels were surveyed during the rainy (March and April and dry (August and September seasons of 2009, using hoop traps. For the analysis of population structure, additional data were taken in March and August, 2008. A total of 169 individuals were captured in flooded forest (igapó, lakes of the coastal plain and, occasionally, in temporary pools. Capture rates were highest in the coastal plain lake, possibly due to the greater availability of the fruits that form part of the diet of R. p. punctularia. Of the physical-chemical variables measured, salinity appeared to be the only factor to have a significant negative effect on capture rates. The sex ratio was only slightly biased to females, and did not vary between habitats or seasons. Straight carapace length was significantly larger in females, but did not vary between habitats. Overall, the evidence indicates that both biotic and abiotic factors like food availability, low current and salinity, influence the habitats selection and use by R. p. punctularia on Algodoal-Maiandeua Island.Rhinoclemmys punctularia punctularia es un quelonio semi-acuático, con amplia distribución geográfica. El presente trabajo analiza la densidad relativa, proporción sexual y el uso de hábitat de esta especie en la isla de Algodoal-Maiandeua, en el litoral Norte de Brasil. Cuatro hábitats distintos fueron muestreados durante los períodos de lluvias y seco de 2009, en donde se utilizaron trampas de aro. Muestras de 2008 (marzo-agosto también se emplearon para el análisis de la estructura de la población. Asimismo, fueron encontrados

  7. Impact of insecticides used to control Spodoptera frugiperda (J.E. Smith in corn on survival, sex ratio, and reproduction of Trichogramma pretiosum Riley offspring

    Directory of Open Access Journals (Sweden)

    Jander R Souza

    2013-06-01

    Full Text Available Corn (Zea mays L. is cultivated in large areas and considered one of the world's major cereal crops. There are several arthropod pests that can reduce its production such as the fall armyworm, Spodoptera frugiperda (J.E. Smith (Lep.: Noctuidae, which is considered to be the main pest for corn. Fall armyworm is primarily controlled by insecticides. The use of biological control agents to manage this pest is growing with an emphasis on the egg parasitoid Trichogramma pretiosum Riley (Hym.: Trichogrammatidae. Thus, the aim of this research was to evaluate the impact of the following insecticides (g ai L-1 beta-cypermethrin (0.03, chlorfenapyr (0.60, chlorpyrifos (0.96, spinosad (0.16, etofenprox (0.10, triflumuron (0.08, alfa-cypermethrin/teflubenzuron (0.0425/0.0425, and lambda-cyhalothrin/thiamethoxam (0.11/0.083 on survival, sex ratio, reproduction, and T. pretiosum offspring. Distilled water was used as a control. Commercial insecticide formulations were diluted in distilled water. Bioassays used Anagasta kuehniella eggs treated with insecticides which were afterwards exposed to parasitism. Bioassays were conducted under controlled conditions at 25 ± 2 °C, 70 ± 10% RH, and 12:12 h photoperiod. Alfa-cypermethrin/teflubenzuron, beta-cypermethrin, chlorpyrifos, chlorfenapyr, spinosad, etofenprox, and lambda-cyhalothrin/thiamethoxam reduced parasitism capacity of maternal generation females as well as the percentage of insect emergence from the F1 generation. Only triflumuron was selective for T. pretiosum and can be recommended along with this parasitoid in fall armyworm management programs in corn.

  8. Characterization of the factor VIII defect in 147 patients with sporadic hemophilia A: Family studies indicate a mutation type-dependent sex ratio of mutation frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Becker, J.; Schmidt, W.; Olek, K. [Univ. of Bonn (Germany)] [and others

    1996-04-01

    The clinical manifestation of hemophilia A is caused by a wide range of different mutations. In this study the factor VIII genes of 147 severe hemophilia A patients-all exclusively from sporadic families-were screened for mutations by use of the complete panel of modern DNA techniques. The pathogenous defect could be characterized in 126 patients (85.7%). Fifty-five patients (37.4%) showed a F8A-gene inversion, 47 (32.0%) a point mutation, 14 (9.5%) a small deletion, 8 (5.4%) a large deletion, and 2 (1.4%) a small insertion. Further, four (2.7%) mutations were localized but could not be sequenced yet. No mutation could be identified in 17 patients (11.6%). Sixteen (10.9%) of the P identified mutations occurred in the B domain. Four of these were located in an adenosine nucleotide stretch at codon 1192, indicating a mutation hotspot. Somatic mosaicisms were detected in 3 (3.9%) of 76 patients` mothers, comprising 3 of 16 de novo mutations in the patients` mothers. Investigation of family relatives allowed detection of a de novo mutation in 16 of 76 two-generation and 28 of 34 three-generation families. On the basis of these data, the male:female ratio of mutation frequencies (k) was estimated as k = 3.6. By use of the quotients of mutation origin in maternal grandfather to patient`s mother or to maternal grandmother, k was directly estimated as k = 15 and k = 7.5, respectively. Considering each mutation type separately, we revealed a mutation type-specific sex ratio of mutation frequencies. Point mutations showed a 5-to-10-fold-higher and inversions a >10-fold- higher mutation rate in male germ cells, whereas deletions showed a >5-fold-higher mutation rate in female germ cells. Consequently, and in accordance with the data of other diseases like Duchenne muscular dystrophy, our results indicate that at least for X-chromosomal disorders the male:female mutation rate of a disease is determined by its proportion of the different mutation types. 68 refs., 1 fig., 5 tabs.

  9. Reduction of radon progeny concentration in ordinary room due to a mixing fan

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Jarad, F.; Sextro, R.G.

    1988-01-01

    Three experiments were carried out at the Indoor Air Quality Research House (IAQRH) at Lawrence Berkeley Laboratory, University of California, to study the effect on the radon progeny of operating a mixing fan. At the beginning of every experiment, about 15 kBq.m/sup -3/ of radon was injected into a 36 m/sup 3/ ordinary room. Measurements were conducted with three different aerosol particle concentrations of about 10/sup 2/, 10/sup 4/ and 10/sup 5/ per cm/sup 3/. Real-time measurements of radon and progeny concentrations, particles and environmental parameters, were made throughout the experiments. Measurements of plated out activity on the surfaces of internal walls of the room and fan blades were measured directly by filter papers and CR-39 nuclear track detectors placed on the surfaces. The ratio of plated out activity to the total progeny activity in the room varied from 17% to 84%, in inverse relation to the particle concentrations. More than 99% of the plateout activity was found on walls and less than 1% on the fan blades. (author).

  10. Reduction of radon progeny concentration in ordinary room due to a mixing fan

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Jarad, F. (University of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Mechanical Engineering); Sextro, R.G. (Lawrence Berkeley Lab., CA (USA))

    1988-01-01

    Three experiments were carried out at the Indoor Air Quality Research House (IAQRH) at Lawrence Berkeley Laboratory, University of California, to study the effect of operating a mixing fan on the radon progeny. In every experiment, about 15 KBq.m{sup -3} of radon was injected into a 36 m3 ordinary room. Measurements were conducted with three different aerosol particle concentrations of about 10{sup 2}, 10{sup 4} and 10{sup 5} per cm3. Real-time measurements of radon and progeny concentrations, particles, and environmental parameters were made throughout the experiments. Measurements of plate-out activity on the surfaces of internal walls of the room were measured directly by filter papers and CR-39 nuclear track detectors, while on fan blades CR-39 detectors were used. The ratio of plated-out activity to the total progeny activity in the room varied from 17% to 84%. More than 99% of the plated-out activity was found on walls and less than 1% on fan blades. (author).

  11. Inheritance of nitrogen use efficiency in inbred progenies of tropical maize based on multivariate diallel analysis.

    Science.gov (United States)

    Guedes, Fernando Lisboa; Diniz, Rafael Parreira; Balestre, Marcio; Ribeiro, Camila Bastos; Camargos, Renato Barbosa; Souza, João Cândido

    2014-01-01

    The objective of our study was to characterize and determine the patterns of genetic control in relation to tolerance and efficiency of nitrogen use by means of a complete diallel cross involving contrasting inbred progenies of tropical maize based on a univariate approach within the perspective of a multivariate mixed model. Eleven progenies, previously classified regarding the tolerance and responsiveness to nitrogen, were crossed in a complete diallel cross. Fifty-five hybrids were obtained. The hybrids and the progenies were evaluated at two different nitrogen levels, in two locations. The grain yield was measured as well as its yield components. The heritability values between the higher and lower nitrogen input environment did not differ among themselves. It was observed that the general combining ability values were similar for both approaches univariate and multivariate, when it was analyzed within each location and nitrogen level. The estimate of variance of the specific combining ability was higher than general combining ability estimate and the ratio between them was 0.54. The univariate and multivariate approaches are equivalent in experiments with good precision and high heritability. The nonadditive genetic effects exhibit greater quantities than the additive genetic effects for the genetic control of nitrogen use efficiency.

  12. Inheritance of Nitrogen Use Efficiency in Inbred Progenies of Tropical Maize Based on Multivariate Diallel Analysis

    Directory of Open Access Journals (Sweden)

    Fernando Lisboa Guedes

    2014-01-01

    Full Text Available The objective of our study was to characterize and determine the patterns of genetic control in relation to tolerance and efficiency of nitrogen use by means of a complete diallel cross involving contrasting inbred progenies of tropical maize based on a univariate approach within the perspective of a multivariate mixed model. Eleven progenies, previously classified regarding the tolerance and responsiveness to nitrogen, were crossed in a complete diallel cross. Fifty-five hybrids were obtained. The hybrids and the progenies were evaluated at two different nitrogen levels, in two locations. The grain yield was measured as well as its yield components. The heritability values between the higher and lower nitrogen input environment did not differ among themselves. It was observed that the general combining ability values were similar for both approaches univariate and multivariate, when it was analyzed within each location and nitrogen level. The estimate of variance of the specific combining ability was higher than general combining ability estimate and the ratio between them was 0.54. The univariate and multivariate approaches are equivalent in experiments with good precision and high heritability. The nonadditive genetic effects exhibit greater quantities than the additive genetic effects for the genetic control of nitrogen use efficiency.

  13. Evolution journalière du sex-ratio dans une population de Mononychellus tanajoa Bondar (Acari: Tetranychidae en laboratoire, paramètres de la dynamique des populations

    Directory of Open Access Journals (Sweden)

    Badegana, AM.

    2003-01-01

    Full Text Available Sex-ratio Daily Evolution in a Population of Mononychellus tanajoa Bondar (Acari: Tetranychidae in the Laboratory, Population Dynamics Parameters. The sex-ratio (100.males/females of offsprings laid by fertilized female parents of Mononychellus tanajoa Bondar and its daily evolution was studied in the laboratory. The highest sex-ratio value 900 (90.0% male offsprings was obtained on the first day of the oviposition and the lowest value 7.2 (6.7% male offsprings on the 16th day of the oviposition period which lasted 38.1 ± 4.9 days (mean ± standard deviation. From a total number of 118.0 ± 10.9 offsprings, 94.0 ± 10.5 (on the average 79.7% were ''laid'' during the first half of the oviposition period. The results also show that from a total number of 88.0 ± 8.3 female offsprings, 74.0 ± 8.0 (84.1% were ''laid'' during the first half of the oviposition period whereas from a total number of 30.0 ± 2.7 male offsprings, 20.0 ± 2.5 (66.7% were ''laid'' within the same period. The sex-ratio of each fertilized female parent was 31.9 ± 1.7 (24.2% ± 1.0% male offsprings and the sex-ratio within the population was 34.0 ± 0.0 (25.4% ± 0.1% male offsprings. The intrinsic rate of increase, and the rate of multiplication in one generation were 0.1380 and 79.23 respectively.

  14. Development of a Progeny Marker for Steelhead; A Thesis submitted to Oregon State University.

    Energy Technology Data Exchange (ETDEWEB)

    Shippentower, Gene E. [Oregon State Univ., Corvallis, OR (United States)

    2009-04-15

    This study was undertaken to determine if strontium chloride could be used to create a trans-generational otolith mark in steelhead (Oncorhynchus mykiss). I completed two strontium injection trials and a survey of juvenile steelhead from various steelhead hatcheries. The two trials measured Sr:Ca ratios in otoliths in response to injections and the survey measured the natural variation in Sr:Ca ratios in otoliths of juvenile hatchery steelhead in response to the natural variation. In 2003, adult female Wallowa River, Oregon O. mykiss, were captured at the hatchery and evenly divided between a control group and two treatment groups. These females received an intraperitoneal injection of 1cc/500 g of body weight of a physiologically isotonic solution (0.9% saline) containing concentrations of 0 (control), 1000, or 5000 parts per million (ppm) of strontium chloride hexahydrate (SrCl2* 6H2O). Females were housed in a single outdoor tank until spawned artificially, and a distinct external tag identified each female within each treatment group. In 2004, female steelhead were captured throughout the duration of the adult returns to the Umatilla River basin and injected with 0, 1000, 5000, or 20,000-ppm strontium. In both trials, progeny of fish treated with strontium had significantly higher Sr:Ca ratios in the primordial region of their otoliths as measured using an electron wavelength dispersive microprobe. There was no difference in fertilization rates of eggs and survival rates of fry among treatment groups. Progeny from treated mothers were on average larger than progeny of untreated mothers. The Sr:Ca ratios in otoliths collected from various populations of steelhead were greater than the control values measured in both injections studies. This study suggests that the marking technique works and the utility for such a technique could be used for empirical observations in determining the relative fitness of progeny of adult hatchery origin fish

  15. SEX ALLOCATION IN THE MONOECIOUS HERB BEGONIA SEMIOVATA.

    Science.gov (United States)

    Ågren, Jon; Schemske, Douglas W

    1995-02-01

    Sex-allocation models predict that the evolution of self-fertilization should result in a reduced allocation to male function and pollinator attraction in plants. The evolution of sex allocation may be constrained by both functional and genetic factors, however. We studied sex allocation and genetic variation for floral sex ratio and other reproductive traits in a Costa Rica population of the monoecious, highly selfing annual Begonia semiovata. Data on biomass of floral structures, flower sex ratios, and fruit set in the source population were used to calculate the average proportion of reproductive allocation invested in male function. Genetic variation and genetic correlations for floral sex ratio and for floral traits related to male and female function were estimated from the greenhouse-grown progeny of field-collected maternal families. The proportion of reproductive biomass invested in male function was low (0.34 at flowering, and 0.07 for total reproductive allocation). Significant among-family variation was detected in the size (mass) of individual male and female flowers, in the proportion of male flowers produced, and in the proportion of total flower mass invested in male flowers. Significant among-family variation was also found in flower number per inflorescence, petal length of male and female flowers, and petal number of female flowers. Except for female petal length, we found no difference in the mean value of these characters between selfed and outcrossed progeny, indicating that, with the possible exception of female petal length, the among-family variation detected was not the result of variation among families in the level of inbreeding. Significant positive phenotypic and broad-sense genetic correlations were detected between the mass of individual male and female flowers, between male and female petal length, and between number of male and number of female flowers per inflorescence. The ratio of stamen-to-pistil mass (0.33) was low compared to

  16. Current international intercomparison measurement on radon and its progeny

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, Keizo [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.

    1996-12-01

    The international intercomparison measurement on radon and its progeny was held between the EML of USDOE and several Japanese organisations, using the radon test chamber installed in EML. Japanese results of radon concentration by the active method using the ionization chamber or scintillation cell and the passive method using the solid track detector were about 5% small compared to that of EML. On the results of radon progeny, there were not any large systematic differences between EML and Japanese participants in spite of wide range of deviation except for the results at the condition of low aerosol density. (author)

  17. [Development of progeny after antenatal exposure to lithium oxybutyrate].

    Science.gov (United States)

    Smol'nikova, N M; Allakhverdiev, V D; Liubimov, B I

    1985-01-01

    Experiments on rats were made to study the effect of lithium hydroxybutyrate and to compare it with lithium carbonate effect on the development of the progeny after antenatal exposure to the drugs. It was established that the lithium salts under study did not produce any conclusive effect on the postnatal development of young rats. The activating component was discovered to be predominant in the action of lithium hydroxybutyrate, whereas the action of lithium carbonate was marked by the inhibitory component. As regards the effect on the development of the progeny, lithium hydroxybutyrate was less hazardous than lithium carbonate.

  18. Analysis of case-parent trios for imprinting effect using a loglinear model with adjustment for sex-of-parent-specific transmission ratio distortion

    DEFF Research Database (Denmark)

    Huang, Lam Opal; Infante-Rivard, Claire; Labbe, Aurélie

    2017-01-01

    of the minor allele in control-trios can be added to the loglinear model to adjust for TRD. Adjusting the model removes the inflation in the genotype relative risk (RR) estimate and Type 1 error introduced by non-sex-of-parent-specific TRD. We now propose to further extend this model to estimate an imprinting...... propose a sex-of-parent-specific transmission offset in adjusting the loglinear model to account for ST. This extended model restores the correct RR estimates for child and imprinting effects, adjusts for inflation in Type 1 error, and improves performance on sensitivity and specificity compared...

  19. Segregation and expression of transgenes in the progenies of Bt ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-04-17

    Apr 17, 2012 ... rent progenies of Bt transgenic rice crosses to conventional rice varieties was analyzed by Western dot blotting. The samples derived from GUS positive plants of. Bt transgenic rice crossed to conventional rice varieties were found to produce a higher level of toxin protein, but with greater range of variation.

  20. Selection of carioca common bean progenies resistant to white mold

    Directory of Open Access Journals (Sweden)

    Renato Sérgio Batista Carvalho

    2013-01-01

    Full Text Available A backcross breeding program between commercial common bean cultivars (VC3 and M20 and sources of resistance(Ex-Rico 23 and G122 was conducted with a view toward selecting carioca (beige with brown stripes progenies resistant to whitemold. Forty-eight progenies (27 F2:6 BC1 and 21 F1:5 BC2 were evaluated for yield, growth habit, grain type and pathogen responseby two methodologies for assessment (“straw test” and “oxalic acid”. The methods were effective in discriminating the progenies,showing differing results, for they may assess different resistance mechanisms. Thus, they should be used together. Simultaneousselection for yield, growth habit, grain type and white mold resistance proved to be viable. The most appropriate strategy was to uselower intensities of selection and prioritize traits such as resistance and grain type, which are essential for commercial acceptance.Two progenies proved their superiority for the breeding program for they combine the traits of resistance and favorable grain type.

  1. The study of triploid progenies crossed between different ploidy ...

    African Journals Online (AJOL)

    The study of triploid progenies crossed between different ploidy grapes. L Sun, G Zhang, A Yan, H Xu. Abstract. The cross between different ploidy grape was one of the effective ways to obtain new seedless cultivars, in this study, through testing the changes of the ovule weight and observing its anatomical structure, the ...

  2. Adversity before Conception Will Affect Adult Progeny in Rats

    Science.gov (United States)

    Shachar-Dadon, Alice; Schulkin, Jay; Leshem, Micah

    2009-01-01

    The authors investigated whether adversity in a female, before she conceives, will influence the affective and social behavior of her progeny. Virgin female rats were either undisturbed (controls) or exposed to varied, unpredictable, stressors for 7 days (preconceptual stress [PCS]) and then either mated immediately after the end of the stress…

  3. Segregation and expression of transgenes in the progenies of Bt ...

    African Journals Online (AJOL)

    PCR, Southern blotting and Western dot blotting analysis confirmed that cry1Ab gene was transferred to the genome of conventional rice varieties and it was highly expressed in the different progenies of Bt rice crossed to conventional rice varieties. Among these lines, the highest Bt toxin protein content reached 2.88% of ...

  4. Thoron and thoron progeny measurements in German clay houses.

    Science.gov (United States)

    Gierl, S; Meisenberg, O; Feistenauer, P; Tschiersch, J

    2014-07-01

    In recent years, elevated thoron concentrations were found in houses built of unfired clay. In this study experiments were carried out in 17 traditional and modern clay houses in Germany to obtain an overview of indoor thoron in such houses. Long-term measurements over an 8-week period were performed using a newly developed Unattended Battery-Operated Progeny Measurement Device (UBPM) for measuring thoron progeny. This instrument uses a high-voltage electric field to precipitate radon and thoron progeny on nuclear track detectors. Additional active and passive measurements of radon, thoron and their progeny were performed. The equilibrium equivalent thoron concentration was found to be between 2 and 10 Bq m(-3). Gas concentrations were found to be between 20 and 160 Bq m(-3) for radon and between 10 and 90 Bq m(-3) for thoron 20 cm from the wall. The thoron exposure contributes significantly to the inhalation dose of the dwellers (0.6-4 mSv a(-1)). © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. What is the most appropriate lipid profile ratio predictor for insulin resistance in each sex? A cross-sectional study in Korean populations (The Fifth Korea National Health and Nutrition Examination Survey).

    Science.gov (United States)

    Byun, A Ri; Lee, Sang Wha; Lee, Hong Soo; Shim, Kyung Won

    2015-01-01

    Insulin resistance (IR) reduces reactivity of the target organ to blood insulin. Researchers have attempted to evaluate IR using various serum lipid concentration ratios. We aimed to determine the most strongly IR-predictive lipid profile ratios for each sex by studying associations between lipid concentration ratios and IR using data from the fifth Korea National Health and Nutrition Examination Survey (KNHANES V-1) 2010. Overall, 8958 individuals participated in health interview and examination surveys. Among them, 1910 individuals who completed physical examinations and 8-h fasting blood tests and were older than 20 years of age were enrolled (929 men and 981 women). The lipid-ratio-related study outcomes were the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL-C/HDL-C), triglyceride (TG)/HDL-C, and non-HDL-C (LDL-C + TG/5)/HDL-C ratios. We divided subjects into 4 groups according to lipid profile ratio quartiles for a comparison of homeostasis model assessment (HOMA)-IR values. Regression analyses were performed after adjusting for the confounding factors of age, body mass index, and diabetes mellitus history. HOMA-IR values tended to increase significantly along with LDL-C/HDL-C, TG/HDL-C, and non-HDL-C/HDL-C ratios in both sexes. In men, multiple linear regression analyses showed that after adjusting for confounding factors, a significant positive association remained only with the LDL-C/HDL-C ratio (p = 0.0238, R(2) = 0.3605, root mean squared error [MSE] =0.3512). In women, multiple linear regression analyses showed that after adjusting for confounding factors, significant positive associations remained with the LDL-C/HDL-C (p < 0.0001, R-square = 0.2329, root MSE = 0.3776), TG/HDL-C (p = 0.0001, R(2) = 0.2373, root MSE = 0.3766), and non-HDL-C/HDL-C ratios (p < 0.0001, R(2) = 0.2456, root MSE = 0.3745). The LDL-C/HDL-C ratio in men and LDL-C/HDL-C, TG/HDL-C, and non

  6. The Effect of PCSK1 Variants on Waist, Waist-Hip Ratio and Glucose Metabolism Is Modified by Sex and Glucose Tolerance Status

    DEFF Research Database (Denmark)

    Gjesing, Anette P; Vestmar, Marie A; Jørgensen, Torben

    2011-01-01

    Background: We aimed to evaluate the effects of the G-allele of rs6232 and the C-allele of rs6235 within PCSK1 on measures of body fat and glucose homeostasis in Danish individuals and to assess interactions of genotypes with age, sex and glucose tolerance status. Data were included in meta...... investigated in a subset of 62 glucose-tolerant men during a meal challenge including measures of serum incretins. In men we found an effect on body composition in sex-stratified analyses where the rs6235 C-allele conferred an increased waist circumference of 0.8 cm per allele (0.2–1.5, p = 0......-allele was associated nominally with a 0.6% (0.1–1%, p = 0.01) reduction in fasting glucose, it interacted with glucose tolerance status for traits related to glucose metabolism and analysis among individuals having abnormal glucose tolerance revealed a 5% (20.7–9%, p = 0.02) elevated level of acute insulin response...

  7. Behavior of radon progeny in low frequency electromagnetic fields

    CERN Document Server

    Oda, K; Yamamoto, T

    1999-01-01

    Whether the electro-magnetic (EM) fields are carcinogenic or not still remains to be discussed from scientific point of view. Recently a possibility was pointed out that increased deposition of radon progeny in the EM-fields should enhance exposure dose to internal body. We investigated the behavior of charged sup 2 sup 2 sup 2 Rn progeny and aerosols containing them by measuring the pattern and the magnitude of the deposition rate of decay products on both CR-39 track detectors and imaging plates under various conditions. We concluded that the attachment to wire cables should be increased mainly by electric component of low frequency EM-fields and possibly by electric field induced by strong changing magnetic ones.

  8. Prediction of genetic gains from selection in Arabica coffee progenies.

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Baião de Oliveira

    2011-01-01

    Full Text Available Gains from selection for yield were estimated in Arabica coffee progenies carrying rust-resistance genes. Theexperiment in augmented block design was installed in Três Pontas, state of Minas Gerais. Three blocks were established with sixplants per plot, spaced 3.50 x 0.90 m, in 96 regular (F2 progenies and two control treatments. The plant response to rust wasevaluated on a grade scale in 2008. Yield (bags per hectare was estimated in the growing seasons 2005 to 2008. Significantdifferences between treatments for yield were observed in all harvests, except 2005. The presence of genetic variability amongprogenies allowed significant gain from selection for yield. Under the experimental conditions of this study, selection for yield can beperformed in the first high-yield year, without major losses compared to genetic gain from selection for yield when based on the meanof four harvests.

  9. Selection of arabica coffee progenies tolerant to heat stress

    Directory of Open Access Journals (Sweden)

    Alexsandro Lara Teixeira

    2015-07-01

    Full Text Available Due to high temperatures, practically all coffee farms in the state of Rondonia are of the C. canephora species. Thus, importing arabica coffee from other states becomes necessary for composition of blends, as well as for the specialty or gourmet coffee market. The purpose of this study was to select arabica coffee genotypes that exhibit satisfactory agronomic performance under high temperature conditions. The experiment was conducted in OuroPreto do Oeste, RO, Brazil, with mean annual temperature of 25.8°C and mean annual rainfall of 2300mm year-1. The experiment was composed of 114 arabica coffee genotypes, with 103 progenies and eleven control cultivars, provided by EPAMIG. A randomized block experimental design was used with three replications, spacing of 3.0x1.0 meters and five plants per plot. All the crop seasons showed significant difference for the green coffee yield trait. In joint analysis, significant differences were detected among progenies and control cultivars. In the average of the four harvests, green coffee yield was 32.38 bags ha-1. The cultivars 'CatuaíVermelho IAC 15', 'Obatã IAC 1669-20' and 'Catucaí Amarelo 2SLCAK' stood out, achieving yields greater than 40 bags ha-1. The gain obtained from selection was 14.33 bags ha-1, which is equivalent to an increase of 44.04% in production of green coffee. The progeny H514-7-10-6-2-3-9 stood out with an average yield of 51.20 bags ha-1. In regard to maturation cycle, 56% of the progenies were classified as early maturity and 44% as medium maturity. Late maturity genotypes were not observed

  10. Inheritance of fruit colour in normal and irradiated progenies of brinjal

    Energy Technology Data Exchange (ETDEWEB)

    Gopimony, R.; George, M.K.; Gopinathan Nair, V. (College of Agriculture, Vellayani, Kerala (India))

    1980-12-01

    The inheritance of fruit colour in brinjal (Solanum melongena) was studied by analysing the progeny belonging to the F/sub 1/M/sub 2/, F/sub 1/M/sub 1/ and F/sub 2/M/sub 2/ generations, resulting from a cross between the varieties insanum and purple giant, followed by gamma irradiation. The F/sub 2/ phenotypic frequencies fitted very well with the dihybrid ratio indicating that the fruit colour is governed by two independently inherited genes. Three colour mutants, namely, purple, mottled green and white were induced in the F/sub 1/M/sub 1/ generation by the irradiation. The appearance of these mutants is explained due to independent mutations at either or both of the two goenetic loci. The colour pattern in the F/sub 2/M/sub 2/ progenies derived from the F/sub 1/M/sub 1/ mutants substantiates the two gene mechanism for the inheritance of fruit colour. The genotypes for the different colour types in the F/sub 1/, F/sub 2/ and F/sub 1/M/sub 1/ mutants have been indicated and discussed.

  11. Our men are grinding out: a qualitative examination of sex ratio imbalances, relationship power, and low-income African American women's health.

    Science.gov (United States)

    Bontempi, Jean M Breny; Eng, Eugenia; Quinn, Sandra Crouse

    2008-01-01

    In the United States, the number of HIV/AIDS cases among women of color is increasing, with African American women now comprising 60% of all female AIDS cases. Scholars have attributed this imbalance to social factors. The aim of this study was to explore the impact that relationship power has on heterosexual women's ability to practice safer sex. Five focus groups were conducted with 24 African American women, aged 18-57 years, residing in public housing in rural North Carolina over a six-month period in 2000. Findings suggest that women maintain their independence, despite inequities in relationship power and remain strong to make a better life for their families. Recommendations are made to promote and build upon this social identity that women have in order to help them practice healthier behaviors.

  12. Adult sex ratio effects on male survivorship of Drosophila melanogaster Meigen (Diptera, Drosophilidae Efeito da razão sexual de adultos na curva de sobrevivência de machos de Drosophila melanogaster Meigen (Diptera, Drosophilidae

    Directory of Open Access Journals (Sweden)

    Marcelo Costa

    2010-01-01

    Full Text Available The behavioral biology has a central role in evolutionary biology mainly because the antagonistic relations that occur in the sexual reproduction. One involves the effect of reproduction on the future life expectation. In this scenario, changes in male operational sex ratio could lead to an increase in mortality due to costs associated with excessive courtship and mating displays. Thus, this work experimentally altered the male sex ratio of Drosophila melanogaster Meigen, 1830, to determine its impact on mortality. The results indicated that mortality increases as the sex ratio changes, including modifications in the survivorship curve type and in the curve concavity, measured by entropy.A biologia comportamental tem um papel central na biologia evolutiva principalmente pelas relações antagônicas que ocorrem na reprodução sexuada. Uma destas relações envolve o efeito da reprodução sobre a expectativa de vida futura. Neste cenário, alterações na razão sexual operacional de machos podem levar a um aumento na mortalidade por causa dos custos associados com o excesso de displays de corte e cópulas. Neste sentido este trabalho alterou experimentalmente a razão sexual em machos de Drosophila melanogaster Meigen, 1830, para determinar os efeitos em termos de mortalidade. Os resultados indicam que a mortalidade aumenta a medida que a razão sexual se enviesa incluindo alterações no tipo de curva de sobrevivência e da concavidade da curva, medida pela entropia.

  13. Progeny Clustering: A Method to Identify Biological Phenotypes

    Science.gov (United States)

    Hu, Chenyue W.; Kornblau, Steven M.; Slater, John H.; Qutub, Amina A.

    2015-01-01

    Estimating the optimal number of clusters is a major challenge in applying cluster analysis to any type of dataset, especially to biomedical datasets, which are high-dimensional and complex. Here, we introduce an improved method, Progeny Clustering, which is stability-based and exceptionally efficient in computing, to find the ideal number of clusters. The algorithm employs a novel Progeny Sampling method to reconstruct cluster identity, a co-occurrence probability matrix to assess the clustering stability, and a set of reference datasets to overcome inherent biases in the algorithm and data space. Our method was shown successful and robust when applied to two synthetic datasets (datasets of two-dimensions and ten-dimensions containing eight dimensions of pure noise), two standard biological datasets (the Iris dataset and Rat CNS dataset) and two biological datasets (a cell phenotype dataset and an acute myeloid leukemia (AML) reverse phase protein array (RPPA) dataset). Progeny Clustering outperformed some popular clustering evaluation methods in the ten-dimensional synthetic dataset as well as in the cell phenotype dataset, and it was the only method that successfully discovered clinically meaningful patient groupings in the AML RPPA dataset. PMID:26267476

  14. Phytochemical profile of morphologically selected yerba-mate progenies

    Directory of Open Access Journals (Sweden)

    Alice Teresa Valduga

    2016-02-01

    Full Text Available ABSTRACT Yerba-mate (Ilex paraguariensis St. Hil is a native South American species. Plant progenies are populations that differ in terms of their productivity, morphology and phytochemical profile. This study aimed to determine the concentration of primary and secondary metabolites, such as antioxidants, in leaves, of yerba-mate progenies selected based on morphological characteristics. We evaluated the centesimal composition of secondary metabolites in the leaves of five yerba-mate plants. Methylxanthines and phenolic compounds were determined by UPLC-PDA, and antioxidant activity by measuring DPPH scavenging. Significant differences were found in centesimal composition and the contents of caffeine, theobromine, rutin and chlorogenic acid, as well as antioxidant activities, in selected progenies. The IC50 values were correlated with the chlorogenic acid levels (r2 = 0.5242 and soluble content (r2 = 0.7686. The morphological characteristics observed in yerba-mate leaves can be used as a tool for plant selection, to obtain matrices with different phytochemical profiles as a genetic material source.

  15. Safe sex

    Science.gov (United States)

    ... sex; Sexually transmitted - safe sex; GC - safe sex; Gonorrhea - safe sex; Herpes - safe sex; HIV - safe sex; ... contact. STIs include: Chlamydia Genital herpes Genital warts Gonorrhea Hepatitis HIV HPV Syphilis STIs are also called ...

  16. A non invasive method for the study of the sex-ratio in a population of Myotis myotis and Myotis blythii (Chiroptera in Piedmont region (Italy

    Directory of Open Access Journals (Sweden)

    F. Borghese

    2009-01-01

    Full Text Available This study contributes to the knowledge of demographic structures of the two sympatric, sister species Myotis myotis and Myotis blythii (Chiroptera. The sites investigated were the Abbazia di Santa Maria in Staffarda and the Castello Ducale in Agliè, known to accommodate the larger Myotis colonies in North-Western Italy. Sampling were conduced in summer 2006. During this season tens to hundreds of females gather togheter to form the so called nurseries, composed by mothers with their litters. With the end of summer, males reach the nurseries for mating. Since these species are severely endangered of extinction, we adopted a non-invasive, opportunistic sampling method based on collection of feces, although tissues from died specimens were harvested as a control of the method. Total DNAs extracted from stool samples were amplified using a pair of specific primers for the DBY8 locus on the Y chromosome, along with an internal control shared by both sexes. The results showed that the colony located in the Abbazia di Staffarda is a typical nursery, while in the Castello di Agliè the situation in composite, because sorting of individuals describes this latter community as both a nursery and a reproductive colony.

  17. Inherited XX sex reversal originating from wild medaka populations.

    Science.gov (United States)

    Shinomiya, A; Otake, H; Hamaguchi, S; Sakaizumi, M

    2010-11-01

    The teleost fish, medaka (Oryzias latipes), has an XX/XY sex-determining mechanism. A Y-linked DM domain gene, DMY, has been isolated by positional cloning as the sex-determining gene in this species. Previously, we conducted a field survey of genotypic sex and found that approximately 1% of wild medaka are sex-reversed (XX males and XY females). Here, we performed genetic analyses of nine spontaneous XX sex-reversed males to elucidate its genetic basis. In all cases, the F(1) progeny were all females, whereas XX males reappeared in the backcross (BC) progeny, suggesting that XX sex reversal is a recessive trait. Although the incidences of sex reversal in the BC progeny were mostly low, 40% were males derived from one XX male. We performed linkage analysis using 55 BC males and located a single major factor, sda-1 (sex-determining autosomal factor-1), controlling sex reversal in an autosomal linkage group. Thus, genes involved in the sex-determining pathway can be isolated from spontaneous mutants in wild populations.

  18. Efficacy of exogenous hormone (GnRHa) for induced breeding of climbing perch Anabas testudineus (Bloch, 1792) and influence of operational sex ratio on spawning success.

    Science.gov (United States)

    Mandal, Babita; Kumar, Rajesh; Jayasankar, P

    2016-08-01

    The climbing perch, Anabas testudineus, is an air-breathing fish having great consumer preference as a food fish and is considered a prime candidate species for aquaculture. Spawning success is an important issue while using hormones for captive induced breeding. In the first experiment, a trial was conducted to assess the efficacy of a synthetic Gonadotropin Releasing Hormone analog (sGnRHa) on the spawning success of climbing perch. Female fish were administered six different doses each with a single intramuscular injection of sGnRHa hormone at 0.002 (TOD1), 0.005 (TOD2), 0.01 (TOD3), 0.015 (TOD4), 0.02 (TOD5), 0.03 (TOD6) μg/g body weight. Similarly, males were administered half of the hormone dose of females in all the respective treatment groups. The greatest (Pclimbing perch. For this study a different female to male ratio (1:1, 1:2, 1:3 and 1:4) and male to female ratio (1:1, 1:2 and 1:3) were used. There were a greater (Pclimbing perch. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep

    Directory of Open Access Journals (Sweden)

    Amigues Yves

    2002-07-01

    Full Text Available Abstract Inheritance of the ovulation rate (OR in the Lacaune meat breed was studied through records from a small nucleus of 36 hyper-prolific ewes screened on farms on the basis of their natural litter size, and from progeny data of three selected Lacaune sires. These sires were chosen at the AI centre according to their breeding values estimated for the mean and the variability of their daughters' litter size. Non-carrier Lacaune dairy ewes were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve sons (four from each sire were used in turn to inseminate non-carrier Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC progeny were brought from private farms and gathered after weaning on an experimental farm where ovulation rates were recorded in the first and second breeding seasons. With an average of 6.5 records each, the mean OR of hyper-prolific ewes was very high (5.34, and 38.4% of records showed a rate of 6 or more. F1 data showed high repeatability of OR (r = 0.54 within ewe, with significant variability among ewes. High OR (≥ 4 were observed in each family. A segregation analysis provided a significant likelihood ratio and classified the three founders as heterozygous. BC ewes also displayed high repeatability of OR (r = 0.47 and the mean OR varied considerably between families (from 1.24 to 1.78. Seven of the 12 BC families presented high-ovulating ewes (at least one record ≥ 4 and segregation analysis yielded a highly significant likelihood ratio as compared to an empirical test distribution. The high variability of the mean ovulation rate shown by a small group of daughters of BC ewes inseminated by putative carrier F1 rams, and the very high ovulation rate observed for some of these ewe lambs, confirmed the segregation of a major gene with two co-dominant alleles borne by an autosome. The difference between homozygous non-carriers and heterozygous ewes was about one ovulation on the observed scale and 2

  20. Temporal variability of the quality of Taraxacum officinale seed progeny from the East-Ural radioactive trace: is there an interaction between low level radiation and weather conditions?

    Science.gov (United States)

    Pozolotina, Vera N; Antonova, Elena V

    2017-03-01

    The multiple stressors, in different combinations, may impact differently upon seed quality, and low-level doses of radiation may enhance synergistic or antagonistic effects. During 1991-2014 we investigated the quality of the dandelion (Taraxacum officinale s.l.) seed progeny growing under low-level radiation exposure at the East-Ural Radioactive Trace (EURT) area (result of the Kyshtym accident, Russia), and in plants from areas exposed to background radiation. The viability of the dandelion seed progeny was assessed according to chronic radiation exposure, accounting for the variability of weather conditions among years. Environmental factors (temperature, precipitation, and their ratio in different months) can modify the radiobiological effects. We found a wide range of possible responses to multiple stressors: inhibition, stimulation, and indifferent effects in different seasons. The intraspecific variability of the quality of dandelion seed progeny was greatly increased under conditions of low doses of chronic irradiation. Temperature was the most significant factor for seed progeny formation in the EURT zone, whereas the sums of precipitation and ratios of precipitation to temperature dominantly affected organisms from the background population.

  1. EVALUATION OF LOWER FACE HEIGHTS AND RATIOS ACCORDING TO SEX. 213\tEvaluación de las alturas y proporciones de la parte inferior de la cara en relación al sexo

    Directory of Open Access Journals (Sweden)

    Ayla Kurkcuoglu

    2016-03-01

    . This study was conducted with the aim of determining lower face height ratios in Baskent University students and evidencing possible sex-related differences. The study was performed on 95 female and 101 male, aged 18-25, atotal of 196 Turkish volunteer students. Lateral photogrammetric images were acquired by the same person for all subjects in natural head position, with their mouth closed in normal posture. The images were transferred to a computing environment. The determination of six anthropometric points in the vertical plane, the measurement of their relative distances and the calculation of seven ratios were done by the same person on all photographs. A significant difference according to the subjects' sex was identified in all seven parameters measured among the anthropometric landmarks. When the lower face height ratios were evaluated the largest one was the upper vermilion height/lower vermilion height ratio both in males and females,and the smallest one was the upper vermilion height/upper lip height ratio in female subjects and the upper lip height/height of the lower face  in males. We hypothesize that the knowledge of certain facial ratios and their differences according to sex and race may serve as a guide for therapy planning in different surgical interventions, orthodontic follow-up and personal identification. 

  2. GENETIC VARIABILITY IN YOUNG PROGENIES OF AÇAIZEIRO

    Directory of Open Access Journals (Sweden)

    João Tomé de Farias Neto

    2005-12-01

    Full Text Available This work aimed at studying the genetic variability in young progenies of açaizeiro population. The experiment wasinstalled in the physical base of Tomé-Açu of the Embrapa Eastern Amazônia, involving the study of 25 progenies of half sibdelineated in látice 5 x 5. The experiment consisted of two repetitions and five plants per plot. Plant height (AP and diameter (DFC,number of live leaves (NFV and tillers (NP were obtained twelve months after planting. The analyses of variance showed that,except plant height and number of leaves characteristics, it had significant differences 5 % of probability for diameter plant andnumber of tillers. Values estimated in the superior extremity of the interval of variation for the characteristic appraised point outpromising individuals to be selected for producing fruits, regarding diameter of the plant, due to the fact that these characters arecorrelated positively. The biggest estimates of genetic parameters had been gotten in relation to the characteristic number of tillers,followed by plant diameter.

  3. Sudetic larch in Germany - Results of provenance and progeny research

    Energy Technology Data Exchange (ETDEWEB)

    Weisgerber, H. [Forest Centre for Management Planning, Research and Ecology, Hann Muenden (Germany)

    1995-12-31

    There are only a few older sources of Sudetic larch in Germany. They distinguish themselves by outstanding growth and low susceptibility to canker. This impression was confirmed by results of provenance research. The Sudetic larch tested in comparison with numerous other provenances proved to be fast-growing, site-tolerant, to a large extent insusceptible to canker, with straight but also slightly to moderately curved stems. The Sudetic provenances behave remarkably uniformly as regards these characteristics. In addition to provenance research investigations have been going on for a long time in Germany into individual differences within the Sudetic larch populations. A report is given on the results of progeny tests from free and controlled pollination, using the example of a seed orchard consisting of 54 clones. We point also to possibilities for improving stem quality by selection steps. The results of provenance and progeny research on Sudetic larch are in the meantime being put to use to a large extent in practical forestry. The forest administrations of various federal lands recommend the use of reproductive material of Sudetic origin and from seed orchards. 20 refs, 3 figs

  4. Genome structure and emerging evidence of an incipient sex chromosome in Populus

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Tongming [ORNL; DiFazio, Stephen P [West Virginia University; Gunter, Lee E [ORNL; Zhang, Xinye [ORNL; Sewell, Mitchell [ORNL; Woolbright, Dr. Scott [North Arizona University; Allan, Dr. Gery [North Arizona University; Kelleher, Colin [University of British Columbia, Vancouver; Douglas, Carl [University of British Columbia, Vancouver; Wang, Prof. Mingxiu [Nanjing Forestry University, China; Tuskan, Gerald A [ORNL

    2008-01-01

    The genus Populus consists of dioecious woody species with largely unknown genetic mechanisms for gender determination. We have discovered genetic and genomic features in the peritelomeric region of chromosome XIX that suggest this region of the Populus genome is in the process of developing characteristics of a sex chromosome. We have identified a gender-associated locus that consistently maps to this region. Furthermore, comparison of genetic maps across multiple Populus families reveals consistently distorted segregation within this region. We have intensively characterized this region using an F1 interspecific cross involving the female genotype that was used for genome sequencing. This region shows suppressed recombination and high divergence between the alternate haplotypes, as revealed by dense map-based genome assembly using microsatellite markers. The suppressed recombination, distorted segregation, and haplotype divergence were observed only for the maternal parent in this cross. Furthermore, the progeny of this cross showed a strongly male-biased sex ratio, in agreement with Haldane's rule that postulates that the heterogametic sex is more likely to be absent, rare, or sterile in interspecific crosses. Together, these results support the role of chromosome XIX in sex determination and suggest that sex determination in Populus occurs through a ZW system in which the female is the heterogametic gender.

  5. Maternal-engineered nanomaterial exposure disrupts progeny cardiac function and bioenergetics.

    Science.gov (United States)

    Hathaway, Quincy A; Nichols, Cody E; Shepherd, Danielle L; Stapleton, Phoebe A; McLaughlin, Sarah L; Stricker, Janelle C; Rellick, Stephanie L; Pinti, Mark V; Abukabda, Alaeddin B; McBride, Carroll R; Yi, Jinghai; Stine, Seth M; Nurkiewicz, Timothy R; Hollander, John M

    2017-03-01

    Nanomaterial production is expanding as new industrial and consumer applications are introduced. Nevertheless, the impacts of exposure to these compounds are not fully realized. The present study was designed to determine whether gestational nano-sized titanium dioxide exposure impacts cardiac and metabolic function of developing progeny. Pregnant Sprague-Dawley rats were exposed to nano-aerosols (~10 mg/m 3 , 130- to 150-nm count median aerodynamic diameter) for 7-8 nonconsecutive days, beginning at gestational day 5-6 Physiological and bioenergetic effects on heart function and cardiomyocytes across three time points, fetal (gestational day 20 ), neonatal (4-10 days), and young adult (6-12 wk), were evaluated. Functional analysis utilizing echocardiography, speckle-tracking based strain, and cardiomyocyte contractility, coupled with mitochondrial energetics, revealed effects of nano-exposure. Maternal exposed progeny demonstrated a decrease in E- and A-wave velocities, with a 15% higher E-to-A ratio than controls. Myocytes isolated from exposed animals exhibited ~30% decrease in total contractility, departure velocity, and area of contraction. Bioenergetic analysis revealed a significant increase in proton leak across all ages, accompanied by decreases in metabolic function, including basal respiration, maximal respiration, and spare capacity. Finally, electron transport chain complex I and IV activities were negatively impacted in the exposed group, which may be linked to a metabolic shift. Molecular data suggest that an increase in fatty acid metabolism, uncoupling, and cellular stress proteins may be associated with functional deficits of the heart. In conclusion, gestational nano-exposure significantly impairs the functional capabilities of the heart through cardiomyocyte impairment, which is associated with mitochondrial dysfunction. NEW & NOTEWORTHY Cardiac function is evaluated, for the first time, in progeny following maternal nanomaterial inhalation. The

  6. Mapping and validation of the major sex-determining region in Nile tilapia (Oreochromis niloticus L. Using RAD sequencing.

    Directory of Open Access Journals (Sweden)

    Christos Palaiokostas

    Full Text Available Sex in Oreochromis niloticus (Nile tilapia is principally determined by an XX/XY locus but other genetic and environmental factors also influence sex ratio. Restriction Associated DNA (RAD sequencing was used in two families derived from crossing XY males with females from an isogenic clonal line, in order to identify Single Nucleotide Polymorphisms (SNPs and map the sex-determining region(s. We constructed a linkage map with 3,802 SNPs, which corresponded to 3,280 informative markers, and identified a major sex-determining region on linkage group 1, explaining nearly 96% of the phenotypic variance. This sex-determining region was mapped in a 2 cM interval, corresponding to approximately 1.2 Mb in the O. niloticus draft genome. In order to validate this, a diverse family (4 families; 96 individuals in total and population (40 broodstock individuals test panel were genotyped for five of the SNPs showing the highest association with phenotypic sex. From the expanded data set, SNPs Oni23063 and Oni28137 showed the highest association, which persisted both in the case of family and population data. Across the entire dataset all females were found to be homozygous for these two SNPs. Males were heterozygous, with the exception of five individuals in the population and two in the family dataset. These fish possessed the homozygous genotype expected of females. Progeny sex ratios (over 95% females from two of the males with the "female" genotype indicated that they were neomales (XX males. Sex reversal induced by elevated temperature during sexual differentiation also resulted in phenotypic males with the "female" genotype. This study narrows down the region containing the main sex-determining locus, and provides genetic markers tightly linked to this locus, with an association that persisted across the population. These markers will be of use in refining the production of genetically male O. niloticus for aquaculture.

  7. All eggs are not equal: the maternal environment affects progeny reproduction and developmental fate in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Simon C Harvey

    Full Text Available BACKGROUND: Maternal effects on progeny traits are common and these can profoundly alter progeny life history. Maternal effects can be adaptive, representing attempts to appropriately match offspring phenotype to the expected environment and are often mediated via trade-offs between progeny number and quality. Here we have investigated the effect of maternal food availability on progeny life history in the free-living nematode Caenorhabditis elegans. METHODOLOGY/PRINCIPAL FINDINGS: The maternal environment affects both reproductive traits and progeny development. Comparisons of the progeny of worms from high and low maternal food environments indicates that low maternal food availability reduces progeny reproduction in good environments, increases progeny reproduction in poor environments and decreases the likelihood that progeny will develop as dauer larvae. These analyses also indicate that the effects on progeny are not a simple consequence of changes in maternal body size, but are associated with an increase in the size of eggs produced by worms at low maternal food availabilities. CONCLUSIONS/SIGNIFICANCE: These results indicate that the maternal environment affects both progeny reproduction and development in C. elegans and therefore that all progeny are not equal. The observed effects are consistent with changes to egg provisioning, which are beneficial in harsh environments, and of changes to progeny development, which are beneficial in harsh environments and detrimental in benign environments. These changes in progeny life history suggest that mothers in poor quality environments may be producing larger eggs that are better suited to poor conditions.

  8. Efeito de diferentes meios de cultivo no desenvolvimento e proporção do sexo de embriões bovinos produzidos in vitro Effect of different culture media on development and sex ratio of bovine embryos fertilized in vitro

    Directory of Open Access Journals (Sweden)

    S.G.T. Gilardi

    2004-10-01

    Full Text Available Avaliou-se o efeito da suplementação de meios de cultivo sobre o desenvolvimento e proporção do sexo de embriões bovinos fertilizados in vitro. Complexos cumulus-oócitos obtidos de ovários de matadouro foram maturados e fertilizados in vitro. Os zigotos (n= 484 foram distribuídos aleatoriamente em meio CR2aa, contendo soro fetal bovino (SFB (T1, albumina sérica bovina (BSA (T2 ou BSA mais insulina:transferrina:selênio e vitaminas (BSA+ (T3, no cultivo embrionário in vitro, a uma atmosfera de 5% CO2 a 38,8ºC em ar. A taxa de clivagem foi observada 72-76 horas pós-fertilização (PF e a taxa de blastocistos com sete e oito dias PF. Os blastocistos (n= 63 foram sexados pela técnica de reação em cadeia de polimerase. A taxa de clivagem em T2 foi maior (P0,05 entre T2 e T3, porém menor (P0,05 entre os tratamentos. O T1 influenciou o desenvolvimento de blastocistos, mas não teve efeito sobre a proporção do sexo.The effect of culture media on the development and on the sex ratio of bovine embryos fertilized in vitro was studied. Cumulus oocyte-complexes from slaughterhouse ovaries were matured and fertilized in vitro. Zygotes (n= 484 were randomly allotted to different culture media and cultured with their cumulus cells in CR2aa medium and an atmosphere of 5% CO2 in air at 38.8ºC. The fetal calf serum (FCS, bovine seric albumin (BSA or BSA plus insulin:transferrin:selenium and vitamins (BSA+ supplementation effect on embryo culture was evaluated. Cleavage rate was assessed at 72-76h post-fertilization (PF and blastocyst rate on days 7 and 8 PF. The blastocysts (n= 63 were also sexed using polymerase chain reaction. Cleavage rate for BSA medium supplemented was higher (P0.05, but lower (P<0.01 than FCS. Culture medium FCS supplemented affected blastocyst development but not the sex ratio.

  9. First detection of radon progeny recoil tracks by MIMAC

    Science.gov (United States)

    Riffard, Q.; Santos, D.; Guillaudin, O.; Bosson, G.; Bourrion, O.; Bouvier, J.; Descombes, T.; Fourel, C.; Muraz, J.-F.; Lebreton, L.; Maire, D.; Colas, P.; Ferrer-Ribas, E.; Giomataris, I.; Busto, J.; Fouchez, D.; Brunner, J.; Tao, C.

    2017-06-01

    The MIMAC experiment is a μ-TPC project for directional dark matter search. Directional detection strategy is based on the measurement of the WIMP flux anisotropy due to the solar system motion with respect to the dark matter halo. The main purpose of MIMAC project is the measurement of nuclear recoil energy and 3D direction from the WIMP elastic scattering on target nuclei. Since June 2012 a bi-chamber prototype is operating at the Modane underground laboratory. In this paper, we report the first ionization energy and 3D track observations of NRs produced by the radon progeny. This measurement shows the capability of the MIMAC detector and opens the possibility to explore the low energy recoil directionality signature.

  10. RADON PROGENY AS AN EXPERIMENTAL TOOL FOR DOSIMETRY OF NANOAEROSOLS

    Energy Technology Data Exchange (ETDEWEB)

    Ruzer, Lev; Ruzer, Lev S.; Apte, Michael G.

    2008-02-25

    The study of aerosol exposure and dosimetry measurements and related quantitation of health effects are important to the understanding of the consequences of air pollution, and are discussed widely in the scientific literature. During the last 10 years the need to correlate aerosol exposure and biological effects has become especially important due to rapid development of a new, revolutionary industry ?-- nanotechnology. Nanoproduct commerce is predicted to top $1 trillion by 2015. Quantitative assessment of aerosol particle behavior in air and in lung deposition, and dosimetry in different parts of the lung, particularly for nanoaerosols, remains poor despite several decades of study. Direct measurements on humans are still needed in order to validate the hollow cast, animal studies, and lung deposition modeling. We discuss here the use of nanoscale radon decay products as an experimental tool in the study of local deposition and lung dosimetry for nanoaerosols. The issue of the safe use of radon progeny in such measurements is discussed based on a comparison of measured exposure in 3 settings: general population, miners, and in a human experiment conducted at the Paul Scherer Institute (PSI) in Switzerland. One of the properties of radon progeny is that they consist partly of 1 nm radioactive particles called unattached activity; having extremely small size and high diffusion coefficients, these particles can be potentially useful as radioactive tracers in the study of nanometer-sized aerosols. We present a theoretical and experimental study of the correlation between the unattached activity and aerosol particle surface area, together with a description of its calibration and method for measurement of the unattached fraction.

  11. Curious Sex Ratios and Cytoplasmic Genes

    Indian Academy of Sciences (India)

    (ii) that these individuals vary in all sorts of characteristics. (iii)that ... of fitness: it is a measure of the net effect of heritable characteristics on reproductive success. .... Such genes reside within cell organelles such as mitochondria and chloroplasts. Many insects and crustaceans also harbour endosymbionts such as bacteria.

  12. Coexistence of genotypic and temperature-dependent sex determination in pejerrey Odontesthes bonariensis.

    Directory of Open Access Journals (Sweden)

    Yoji Yamamoto

    Full Text Available In this study, we examined whether a homolog of the master sex-determining gene amhy of Odontesthes hatcheri is present and plays any role in testis determination of pejerrey O. bonariensis, a species otherwise known for its strong temperature-dependent sex determination (TSD. Screening of wild and laboratory-reared pejerrey for amhy revealed a high, although not complete linkage with phenotypic sex. The sex ratio in an amhy+/-/amhy-/- full sibling progeny reared during the thermolabile period of sex determination at an intermediate temperature of 25°C was 68.7% male:31.3% female; all amhy+/- fish developed as males whereas about 2/3 and 1/3 of the amhy-/- were female and male, respectively. Expression analyses revealed that amhy transcription began during embryo stage and decreased by the end of sex determination period. The autosomal amha was present in all individuals regardless of amhy genotype; its expression increased significantly from the end of the same period in the gonads of all amhy+/- but only in part of the amhy-/- animals. After histological gonadal differentiation, all gonads of amhy-/- animals with amha ISH signals were testes and those without it were ovaries. These results suggest that amhy is important for testicular differentiation in pejerrey, at least at intermediate temperatures. Thus, we hypothesize that amhy+/- animals differentiate as males by expression of either amhy alone or amhy and amha together whereas the amhy-/- probably rely solely on amha expression. These findings represent the first clear genomic evidence that genotypic and environmental sex determinants can coexist in species with marked TSD such as the pejerrey. The finding of amhy will make possible to monitor wild pejerrey populations for mismatches between genotypic and phenotypic sex and may prove instrumental for field studies addressing the effects of endocrine disruptors or abnormal temperatures on reproduction and the ecological relevance of TSD

  13. Genetic parameters and estimated genetic gains in young rubber tree progenies

    Directory of Open Access Journals (Sweden)

    Cecília Khusala Verardi

    2013-04-01

    Full Text Available The objective of this work was to assess the genetic parameters and to estimate genetic gains in young rubber tree progenies. The experiments were carried out during three years, in a randomized block design, with six replicates and ten plants per plot, in three representative Hevea crop regions of the state of São Paulo, Brazil. Twenty-two progenies were evaluated, from three to five years old, for rubber yield and annual girth growth. Genetic gain was estimated with the multi-effect index (MEI. Selection by progenies means provided greater estimated genetic gain than selection based on individuals, since heritability values of progeny means were greater than the ones of individual heritability, for both evaluated variables, in all the assessment years. The selection of the three best progenies for rubber yield provided a selection gain of 1.28 g per plant. The genetic gains estimated with MEI using data from early assessments (from 3 to 5-year-old were generally high for annual girth growth and rubber yield. The high genetic gains for annual girth growth in the first year of assessment indicate that progenies can be selected at the beginning of the breeding program. Population effective size was consistent with the three progenies selected, showing that they were not related and that the population genetic variability is ensured. Early selection with the genetic gains estimated by MEI can be made on rubber tree progenies.

  14. Cellulose content of tuber cell walls of progeny from a cross ...

    African Journals Online (AJOL)

    Two transgenic potato lines, csr2-1 and csr4-8, containing two different antisense genes, csr2 and csr4, respectively, were crossed to investigate the possibility of achieving reduction in cellulose content in the tuber cell walls of the progeny. The progeny containing both transgenes (double csr2/csr4 transformant) exhibited ...

  15. Relation of Zn, Fe, Cu and Mn between progenies of mate-tree and soil

    Directory of Open Access Journals (Sweden)

    Josiane Cava Guimarães

    2014-06-01

    Full Text Available The mate tea tree (Ilex Paraguariensis St. Hil. has considerable growth in acid a low fertility soils. The knowledge of soil and plant relation will contribute to genetic improvement programs, as highly capable progenies in nutrient acquisition may be selected. The objective of this study was to evaluate the interference of provenance and, or progenies, in relations established among the extractable contents of Zn, Fe, Cu and Mn, via Mehlich-1 (1:10; and EDTA (1%, with the corresponding contents in the mate tea tree leaves. In the experiment two provenances, Ivaí-PR and Barão de Cotegipe-RS, with five progenies each considered as treatments. The samples were distributed in four randomized blocks, totalizing 120 plant leaf samples, related to 120 soil samples of a Red Distrophic Latosol. The results were analyzed and fitted in regression equations. In Ivaí provenance Zn and Mn from the soil correlated with their contents in the leaves for progeny 04, for both extracts. For provenances 08 and 10, soil Mn via EDTA correlated with leaf Mn contents, while via Mehlich-1 only for progeny 10. In the provenance of Barão de Cotegipe, the correlations between soil and leaves for Zn, Fe and Cu occurred for the EDTA extract in the progenies 61, 65 and 69 respectively. For Mn and Cu, via Melich-1 the correlations occurred for progenies 53 and 69 respectively, and still for Cu, via EDTA, for progeny 53.

  16. O sexo masculino vulnerável: razão de masculinidade entre os óbitos fetais brasileiros The vulnerable male, or the sex ratio among fetal deaths in Brazil

    Directory of Open Access Journals (Sweden)

    Alexandre Dias Porto Chiavegatto Filho

    2012-04-01

    Full Text Available Alguns estudos apontam para a existência de vulnerabilidades biológicas inatas masculinas, especialmente no período perinatal. Foi realizada uma análise transversal da mortalidade fetal brasileira segundo sexo, entre 2000 e 2009 (inclusive, conforme características maternas (idade, escolaridade e duração da gestação, utilizando-se dados disponibilizados pelos sistema DATASUS do Ministério da Saúde. Todos os óbitos fetais do período foram incluídos na análise, excetuando-se os casos em que o sexo do feto não foi declarado. A razão de masculinidade (RM encontrada para os óbitos fetais foi de 1,188. As categorias mais relacionadas com maior risco (idade entre 10 e 14 anos, nenhuma escolaridade e gestação com menos de 22 semanas apresentaram maior RM, sendo esses valores, em todos os casos, estatisticamente maiores do que os observados nas outras categorias analisadas (p Some studies indicate the existence of innate male vulnerabilities, especially during the perinatal period. The current study is a cross-sectional analysis of fetal mortality in Brazil according to sex from 2000 to 2009, stratified by maternal characteristics (age, schooling, and gestational age, using Ministry of Health data (DATASUS. The analysis included all fetal deaths from 2000 to 2009, except when the sex of the fetus was not recorded. The male/female sex ratio (SR for all fetal deaths was 1.188. Analysis of maternal characteristics showed that the SR was statistically higher (p < 0.01 in mothers that were younger (10-14 years, had no formal schooling, and with gestational age < 22 weeks. The study showed a statistically higher-than-expected SR (p < 0.01 for 13 underlying causes of death and a lower SR for two others. The results suggest a potential innate male vulnerability.

  17. Golden Ratio

    Indian Academy of Sciences (India)

    Our attraction to another body increases if the body is sym- metrical and in proportion. If a face or a structure is in pro- portion, we are more likely to notice it and find it beautiful. The universal ratio of beauty is the 'Golden Ratio', found in many structures. This ratio comes from Fibonacci numbers. In this article, we explore this ...

  18. Golden Ratio

    Indian Academy of Sciences (India)

    Our attraction to another body increases if the body is symmetricaland in proportion. If a face or a structure is in proportion,we are more likely to notice it and find it beautiful.The universal ratio of beauty is the 'Golden Ratio', found inmany structures. This ratio comes from Fibonacci numbers.In this article, we explore this ...

  19. Early growth performance of full-sib Acacia auriculiformis x Acacia mangium F1 hybrid progenies at three different sites

    Science.gov (United States)

    Shah Aimin, Atirah Abdullah; Abdullah, Mohd Zaki; Muhammad, Norwati; Ratnam, Wickneswari

    2014-09-01

    Field trials of 14 full sib Acacia auriculiformis x Acacia mangium F1 hybrid progenies were evaluated for growth performance at three sites (Bintulu, Mentakab and Segamat). Results indicated that there were significant differences (p> 0.05) for diameter breast height (Dbh) and total height (Ht) among the progenies and different sites. Superior progenies have been identified for future tree selection and improvement.

  20. Maternal Diet and Insulin-Like Signaling Control Intergenerational Plasticity of Progeny Size and Starvation Resistance.

    Directory of Open Access Journals (Sweden)

    Jonathan D Hibshman

    2016-10-01

    Full Text Available Maternal effects of environmental conditions produce intergenerational phenotypic plasticity. Adaptive value of these effects depends on appropriate anticipation of environmental conditions in the next generation, and mismatch between conditions may contribute to disease. However, regulation of intergenerational plasticity is poorly understood. Dietary restriction (DR delays aging but maternal effects have not been investigated. We demonstrate maternal effects of DR in the roundworm C. elegans. Worms cultured in DR produce fewer but larger progeny. Nutrient availability is assessed in late larvae and young adults, rather than affecting a set point in young larvae, and maternal age independently affects progeny size. Reduced signaling through the insulin-like receptor daf-2/InsR in the maternal soma causes constitutively large progeny, and its effector daf-16/FoxO is required for this effect. nhr-49/Hnf4, pha-4/FoxA, and skn-1/Nrf also regulate progeny-size plasticity. Genetic analysis suggests that insulin-like signaling controls progeny size in part through regulation of nhr-49/Hnf4, and that pha-4/FoxA and skn-1/Nrf function in parallel to insulin-like signaling and nhr-49/Hnf4. Furthermore, progeny of DR worms are buffered from adverse consequences of early-larval starvation, growing faster and producing more offspring than progeny of worms fed ad libitum. These results suggest a fitness advantage when mothers and their progeny experience nutrient stress, compared to an environmental mismatch where only progeny are stressed. This work reveals maternal provisioning as an organismal response to DR, demonstrates potentially adaptive intergenerational phenotypic plasticity, and identifies conserved pathways mediating these effects.

  1. Inference of genetic diversity in popcorn S3 progenies.

    Science.gov (United States)

    Pena, G F; do Amaral, A T; Ribeiro, R M; Ramos, H C C; Boechat, M S B; Santos, J S; Mafra, G S; Kamphorst, S H; de Lima, V J; Vivas, M; de Souza Filho, G A

    2016-05-09

    Molecular markers are a useful tool for identification of complementary heterotic groups in breeding programs aimed at the production of superior hybrids, particularly for crops such as popcorn in which heterotic groups are not well-defined. The objective of the present study was to analyze the genetic diversity of 47 genotypes of tropical popcorn to identify possible heterotic groups for the development of superior hybrids. Four genotypes of high genetic value were studied: hybrid IAC 125, strain P2, and varieties UENF 14 and BRS Angela. In addition, 43 endogamous S3 progenies obtained from variety UENF 14 were used. Twenty-five polymorphic SSR-EST markers were analyzed. A genetic distance matrix was obtained and the following molecular diversity parameters were estimated: number of alleles, number of effective alleles, polymorphism information content (PIC), observed and expected heterozygosities, Shannon diversity index, and coefficient of inbreeding. We found a moderate PIC and high diversity index, indicating that the studied population presents both good discriminatory ability and high informativeness for the utilized markers. The dendrogram built based on the dissimilarity matrix indicated six distinct groups. Our findings demonstrate the genetic diversity among the evaluated genotypes and provide evidence for heterotic groups in popcorn. Furthermore, the functional genetic diversity indicates that there are informative genetic markers for popcorn.

  2. Sexing young snowy owls

    Science.gov (United States)

    Seidensticker, M.T.; Holt, D.W.; Detienne, J.; Talbot, S.; Gray, K.

    2011-01-01

    We predicted sex of 140 Snowy Owl (Bubo scandiacus) nestlings out of 34 nests at our Barrow, Alaska, study area to develop a technique for sexing these owls in the field. We primarily sexed young, flightless owls (3844 d old) by quantifying plumage markings on the remiges and tail, predicting sex, and collecting blood samples to test our field predictions using molecular sexing techniques. We categorized and quantified three different plumage markings: two types of bars (defined as markings that touch the rachis) and spots (defined as markings that do not touch the rachis). We predicted sex in the field assuming that males had more spots than bars and females more bars than spots on the remiges and rectrices. Molecular data indicated that we correctly sexed 100% of the nestlings. We modeled the data using random forests and classification trees. Both models indicated that the number and type of markings on the secondary feathers were the most important in classifying nestling sex. The statistical models verified our initial qualitative prediction that males have more spots than bars and females more bars than spots on flight feathers P6P10 for both wings and tail feathers T1 and T2. This study provides researchers with an easily replicable and highly accurate method for sexing young Snowy Owls in the field, which should aid further studies of sex-ratios and sex-related variation in behavior and growth of this circumpolar owl species. ?? 2011 The Raptor Research Foundation, Inc.

  3. Spatial dependence in experiments of progeny selection for bean ( Phaseolus vulgaris L. yield

    Directory of Open Access Journals (Sweden)

    Michele Jorge da Silva

    Full Text Available ABSTRACT In field experiments, it is often assumed that errors are statistically independent, but not always this condition is met, compromising the results. An inappropriate choice of the analytical model can compromise the efficiency of breeding programs in preventing unpromising genotypes from being selected and maintained in the next selection cycles resulting in waste of time and resources. The objective of this study was to evaluate the spatial dependence of errors in experiments evaluating grain yield of bean progenies using analyses in lattice and randomized blocks. And also evaluate the efficiency of geostatistical models to describe the structure of spatial variability of errors. The data used in this study derived from experiments arranged in the lattice design and analyzed as lattice or as randomized blocks. The Durbin-Watson test was used to verify the existence of spatial autocorrelation. The theoretical semivariogram was fitted using geostatistical models (exponential, spherical and Gaussian to describe the spatial variability of errors. The likelihood ratio test was applied to assess the significance of the geostatistical model parameters. Of the eight experiments evaluated, five had moderate spatial dependence for the randomized blocks analysis and one for both analyses, in lattice and randomized blocks. The area of the experiments was not a determinant factor of the spatial dependence. The spherical, exponential and Gaussian geostatistical models with nugget effect were suitable to represent the spatial structure in the randomized block analysis. The analysis in lattice was efficient to ensure the independence of errors.

  4. Production of wide hybrids and backcross progenies between Diplotaxis erucoides and crop brassicas.

    Science.gov (United States)

    Vyas, P; Prakash, S; Shivanna, K R

    1995-03-01

    Intergeneric hybrids were produced between D. erucoides (♀), a wild species, and four cultivated species of Brassica, B. campestris, B. juncea, B. napus and B. oleracea, through embryo rescue. The hybrid nature of these plants was confirmed through morphological and cytological studies. Backcross pollinations with the pollen of the respective cultivars yielded BC progenies in the hybrids D. erucoides x B. juncea and D. erucoides x B. napus but not in D. erucoides x B. campestris and D. erucoides x B. oleracea. The hybrid D. erucoides x B. campestris was also used as a bridge species and crossed with B. juncea to raise the hybrid and backcross progenies. F2 progenies were more amenable than f1 hybrids for raising backcross progenies. Although D. erucoides is considered to be a close relative of B. campestris and B. oleracea, incompatibility barriers of this species with different cultivars do not reflect this relationship.

  5. [Genetic polymorphism of clones and their seed progeny in the scotch pine clone plantation].

    Science.gov (United States)

    Korshikov, I I; Demkovich, A E

    2010-01-01

    Genetic variation at 12 allozyme loci (10 of them being polymorphic ones) has been studied in the archive-clone plantation of 23 Pinus sylvestris plus-trees and their seed progeny in the south-east of Ukraine. More than a half of clones had 4-8 heterozygous loci, whereas their seed progeny was marked by a lower variation than maternal trees. Seed progeny was obtained at a high outcrossing rate (t(m) = 95%). The clone progeny was characterized by a high percentage of abnormal allele segregation in megagametophytes. There was also a high frequency of significant deviation in distribution of seed embryo genotypes from the theoretically expected one according to the Hardy-Weinberg law.

  6. Molecular marker analysis of F1 progenies and their parents for ...

    African Journals Online (AJOL)

    Molecular marker analysis of F1 progenies and their parents for carotenoids inheritance in African cassava (Manihot esculenta Crantz). DN Njoku, VE Gracen, SK Offei, IK Asante, EY Danquah, CN Egesi, E Okogbenin ...

  7. Assessment of radon equilibrium factor from distribution parameters of simultaneous radon and radon progeny measurements.

    Science.gov (United States)

    Chen, Jing; Marro, Leonora

    2011-11-01

    In Canada, a radon and radon progeny survey was carried out in the 1970s in 19 cities. To the authors' knowledge, this is the only large survey of simultaneous radon and radon progeny measurements up to the present time. However, the survey was carried out for the purpose of establishing geographic variation of radon and radon progeny; therefore, radon equilibrium factors, F, were not assessed at that time. From the summary results of this large simultaneous radon and radon progeny survey, the characteristics of radon equilibrium factor were assessed. The average F factor assessed from this survey in 12,576 houses is 0.54. The current assessment may indicate that the typical F value of 0.4 recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the International Commission on Radiological Protection (ICRP) could lead to a downward bias in the estimation of radon doses to the lung.

  8. Campylobacter epidemiology from breeders to their progeny in Eastern Spain.

    Science.gov (United States)

    Ingresa-Capaccioni, S; Jiménez-Trigos, E; Marco-Jiménez, F; Catalá, P; Vega, S; Marin, C

    2016-03-01

    While horizontal transmission is a route clearly linked to the spread of Campylobacter at the farm level, few studies support the transmission of Campylobacter spp. from breeder flocks to their offspring. Thus, the present study was carried out to investigate the possibility of vertical transmission. Breeders were monitored from the time of housing day-old chicks, then throughout the laying period (0 to 60 wk) and throughout their progeny (broiler fattening, 1 to 42 d) until slaughter. All samples were analyzed according with official method ISO 10272:2006. Results revealed that on breeder farms, Campylobacter isolation started from wk 16 and reached its peak at wk 26, with 57.0% and 93.2% of positive birds, respectively. After this point, the rate of positive birds decreased slightly to 86.0% at 60 wk. However, in broiler production all day-old chicks were found negative for Campylobacter spp, and the bacteria was first isolated at d 14 of age (5.0%), with a significant increase in detection during the fattening period with 62% of Campylobacter positive animals at the end of the production cycle. Moreover, non-positive sample was determined from environmental sources. These results could be explained because Campylobacter may be in a low concentration or in a non-culturable form, as there were several studies that successfully detected Campylobacter DNA, but failed to culture. This form can survive in the environment and infect successive flocks; consequently, further studies are needed to develop more modern, practical, cost-effective and suitable techniques for routine diagnosis. © 2016 Poultry Science Association Inc.

  9. The hESC line Envy expresses high levels of GFP in all differentiated progeny.

    Science.gov (United States)

    Costa, Magdaline; Dottori, Mirella; Ng, Elizabeth; Hawes, Susan M; Sourris, Koula; Jamshidi, Pegah; Pera, Martin F; Elefanty, Andrew G; Stanley, Edouard G

    2005-04-01

    Human embryonic stem cells (hESCs) have been advanced as a potential source of cells for use in cell replacement therapies. The ability to identify hESCs and their differentiated progeny readily in transplantation experiments will facilitate the analysis of hESC potential and function in vivo. We have generated a hESC line designated 'Envy', in which robust levels of green fluorescent protein (GFP) are expressed in stem cells and all differentiated progeny.

  10. Control of respirable particles and radon progeny with portable air cleaners

    Energy Technology Data Exchange (ETDEWEB)

    Offermann, F.J.; Sextro, R.G.; Fisk, W.J.; Nazaroff, W.W.; Nero, A.V.; Revzan, K.L.; Yater, J.

    1984-02-01

    Eleven portable air cleaning devices have been evaluated for control of indoor concentrations of respirable particles and radon progeny. Following injection of cigarette smoke and radon in a room-size chamber, decay rates for particles and radon progeny concentrations were measured with and without air cleaner operation. Particle concentrations were obtained for total number concentration and for number concentration by particle size. In tests with no air cleaner the natural decay rate for cigarette smoke was observed to be 0.2 hr/sup -1/. Air cleaning rates for particles were found to be negligible for several small panel-filters, a residential ion-generator, and a pair of mixing fans. The electrostatic precipitators and extended surface filters tested had significant particle removal rates, and a HEPA-type filter was the most efficient air cleaner. The evaluation of radon progeny control produced similar results; the air cleaners which were effective in removing particles were also effective in removing radon progeny. At low particle concentrations plateout of the unattached radon progeny is an important removal mechanism. Based on data from these tests, the plateout rate for unattached progeny was found to be 15 hr/sup -1/. The unattached fraction and the overall removal rate due to deposition of attached and unattached nuclides have been estimated for each radon decay product as a function of particle concentration. While air cleaning can be effective in reducing total radon progeny, concentrations of unattached radon progeny can increase with increasing air cleaning. 39 references, 26 figures, 9 tables.

  11. Effects of exposing Drosophila melanogaster parents to ethanol on expression of vestigial in their progeny.

    Science.gov (United States)

    Giesel, J T; Niemann, M M

    1985-03-01

    When parental Drosophila melanogaster were chronically exposed at 28 degrees C or 24 degrees C to ethanol during their larval and pupal stages of development, their progeny, produced when parents were 5-16-day-old adults, showed modified expression of vestigial alleles in heterozygous and homozygous combinations. Parental alcohol effects were dependent on parental rearing temperature. We conclude that parental environment (alcohol, temperature) causes heritable but transitory changes in progeny phenotype that are elicited by exposure of germ cells to alcohol.

  12. High Correlated Paternity Leads to Negative Effects on Progeny Performance in Two Mediterranean Shrub Species.

    Directory of Open Access Journals (Sweden)

    Sofia Nora

    Full Text Available Anthropogenic habitat deterioration can promote changes in plant mating systems that subsequently may affect progeny performance, thereby conditioning plant recruitment for the next generation. However, very few studies yet tested mating system parameters other than outcrossing rates; and the direct effects of the genetic diversity of the pollen received by maternal plants (i.e. correlated paternity has often been overlooked. In this study, we investigated the relation between correlated paternity and progeny performance in two common Mediterranean shrubs, Myrtus communis and Pistacia lentiscus. To do so, we collected open-pollinated progeny from selected maternal plants, calculated mating system parameters using microsatellite genotyping and conducted sowing experiments under greenhouse and field conditions. Our results showed that some progeny fitness components were negatively affected by the high correlated paternity of maternal plants. In Myrtus communis, high correlated paternity had a negative effect on the proportion and timing of seedling emergence in the natural field conditions and in the greenhouse sowing experiment, respectively. In Pistacia lentiscus, seedling emergence time under field conditions was also negatively influenced by high correlated paternity and a progeny survival analysis in the field experiment showed greater mortality of seedlings from maternal plants with high correlated paternity. Overall, we found effects of correlated paternity on the progeny performance of Myrtus communis, a self-compatible species. Further, we also detected effects of correlated paternity on the progeny emergence time and survival in Pistacia lentiscus, an obligate outcrossed species. This study represents one of the few existing empirical examples which highlight the influence that correlated paternity may exert on progeny performance in multiple stages during early seedling growth.

  13. High Correlated Paternity Leads to Negative Effects on Progeny Performance in Two Mediterranean Shrub Species.

    Science.gov (United States)

    Nora, Sofia; Aparicio, Abelardo; Albaladejo, Rafael G

    2016-01-01

    Anthropogenic habitat deterioration can promote changes in plant mating systems that subsequently may affect progeny performance, thereby conditioning plant recruitment for the next generation. However, very few studies yet tested mating system parameters other than outcrossing rates; and the direct effects of the genetic diversity of the pollen received by maternal plants (i.e. correlated paternity) has often been overlooked. In this study, we investigated the relation between correlated paternity and progeny performance in two common Mediterranean shrubs, Myrtus communis and Pistacia lentiscus. To do so, we collected open-pollinated progeny from selected maternal plants, calculated mating system parameters using microsatellite genotyping and conducted sowing experiments under greenhouse and field conditions. Our results showed that some progeny fitness components were negatively affected by the high correlated paternity of maternal plants. In Myrtus communis, high correlated paternity had a negative effect on the proportion and timing of seedling emergence in the natural field conditions and in the greenhouse sowing experiment, respectively. In Pistacia lentiscus, seedling emergence time under field conditions was also negatively influenced by high correlated paternity and a progeny survival analysis in the field experiment showed greater mortality of seedlings from maternal plants with high correlated paternity. Overall, we found effects of correlated paternity on the progeny performance of Myrtus communis, a self-compatible species. Further, we also detected effects of correlated paternity on the progeny emergence time and survival in Pistacia lentiscus, an obligate outcrossed species. This study represents one of the few existing empirical examples which highlight the influence that correlated paternity may exert on progeny performance in multiple stages during early seedling growth.

  14. Prediction of direct and indirect genetic gains and genotypic correlations in rubber tree progenies

    Directory of Open Access Journals (Sweden)

    Cecília Khusala Verardi

    2011-09-01

    Full Text Available The objective of this work was to estimate the genetic parameters, genotypic and phenotypic correlations, and direct and indirect genetic gains among and within rubber tree (Hevea brasiliensis progenies. The experiment was set up at the Municipality of Jaú, SP, Brazil. A randomized complete block design was used, with 22 treatments (progenies, 6 replicates, and 10 plants per plot at a spacing of 3x3 m. Three‑year‑old progenies were assessed for girth, rubber yield, and bark thickness by direct and indirect gains and genotypic correlations. The number of latex vessel rings showed the best correlations, correlating positively and significantly with girth and bark thickness. Selection gains among progenies were greater than within progeny for all the variables analyzed. Total gains obtained were high, especially for girth increase and rubber yield, which were 93.38 and 105.95%, respectively. Young progeny selection can maximize the expected genetic gains, reducing the rubber tree selection cycle.

  15. Meiotic behavior in apomictic Brachiaria ruziziensis × B. brizantha (Poaceae progenies

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    Veridiana Aparecida Fuzinatto

    2012-12-01

    Full Text Available Hybrids combining desirable traits from divergent parents are the main objective of some Brachiaria (Syn. Urochloa P. Beauv. breeding programs. There is great interest in the development of apomictic hybrid cultivars that combine desirable genes such as resistance to spittlebugs, high nutritive value, and tolerance to acid soils. Microsporogenesis of six apomictic progenies resulting from a tetraploid (2n = 4x = 36 cross between B. ruziziensis × B. brizantha was evaluated under light microscopy. Genetic recombination, ensured by multivalent chromosome association and crossing-over at prophase occurred in low frequency among progenies, and in one, recombination was almost nonexistent. The percentage of meiocytes with meiotic abnormalities among progenies ranged from 16.6 % to 85.6 %. Besides an observed irregular chromosome segregation typical of polyploid hybrids in these five progenies, putative meiotic mutations characterized as desynapsis and divergent spindle organization occurred in three progenies. These anomalies caused frequent fractionation of the genome into several microspores of different sizes. In Brachiaria, new cultivars must be apomictic to fix the genotype. However, Brachiaria is a pseudogamous apomict, and viable gametes are necessary to produce viable seeds. Considering meiotic behavior, only two progenies are promising for advancement in the breeding program.

  16. Cytogenetic changes in the liver of progeny of irradiated male rats

    Energy Technology Data Exchange (ETDEWEB)

    Kropacova, K.; Slovinska, L.; Misurova, E. [P.J. Safarik Univ., Kosice (Slovakia)

    2002-06-01

    The transgenerational transmission of radiation damage of rat genom was studied on the basis of cytogenetic changes in somatic cells (hepatocytes). It was found, that the irradiation of rat males with dose of 3 Gy of gamma radiation caused latent cytogenetic damage to the liver, which was expressed during the course of an induced proliferation of hepatocytes (by partial hepatectomy) by lower proliferative activity and a high frequency of chromosomal aberrations. In the progeny of irradiated males (in the F{sub 1} generation), the radiation damage to DNA was manifested by similar changes, i.e. by lower proliferation activity and increase in ''spontaneous'' chromosomal aberration occurrence in liver regeneration after partial hepatectomy. Irradiating the progeny of irradiated males (the total radiation load of the progeny being 3 Gy+3 Gy) caused slighter changes in compared with irradiating the progeny of non-irradiated control males (the total radiation load of the progeny being 0 Gy+3 Gy), which suggests some kind of adaptive response, which was also found in other experimental systems and parameters. An analogous course of RNA and DNA quantitative changes in the liver of the F{sub 0} and F{sub 1} generations of rats confirms the partial transmission of radiation damage of genom to the progeny. (author)

  17. Effect of pollination mode on progeny of Panicum coloratum var. makarikariense: Implications for conservation and breeding

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    Lorena V. Armando

    2017-09-01

    Full Text Available Panicum coloratum var. makarikariense, a perennial grass native to Africa, is adapted to a wide range of soil and climatic conditions with potential to be used as forage in tropical and semi-arid regions around the world. Our objective was to understand how the pollination mode affects viable seed production and further survival of the progeny. We evaluated self- and open-pollinated progenies from different accessions by measuring the seed production of the parents and their germination performance, germination rate and seedling survival. Parents and progeny were also fingerprinted with Simple Sequence Repeats (SSR. Progeny produced through open-pollination resulted in significantly more filled seeds and superior seedling survival than self-pollination. These results indicate that accessions studied here rely heavily on cross-pollination, whereas the contribution of self-pollinated offspring to the population is likely to be low. SSR profiles showed that, on average, 85% of the progeny (arising from cross-pollination possessed paternal specific markers and 100% of them were genetically different from the maternal genotype. All plants examined had 4x = 36 chromosomes. Overall, our findings indicate that var. makarikariense is able to generate highly polymorphic progeny through segregation and recombination. This study provides reference information for the formulation of appropriate strategies for pasture germplasm management, conservation and development of breeding programs. 

  18. ATTEMPTS OF INDUCTION OF SEX-REVERSAL IN CARP (CYPRINUS CARPIO VAR. KOI USING TESTOSTERONE UNDECANOAT

    Directory of Open Access Journals (Sweden)

    A. GROZEA

    2007-10-01

    Full Text Available sexreversalprotocols to obtain inverted males (XX and which are the consequencesusing this hormone for koi carp. To induce sex-reversal, we chose to feed a normalmixed-sex progeny of koi carp with food mixed with 30 (V1, 60 (V2 and 90 (V3 mgTU / kg food, starting at the age of 30 days for a period of 60 days. When fishes had3 months old, they were moved into a bigger aquarium and they were fed withouthormones until the age of 6 months when some of fishes were sacrifices to takesamples for histological studies. At this age the main morphometric traits wereregistered. Our results indicated that the mortality percent raise dependent by thequantity of TU from food, with a maximum value in variant V3 (90 mg TU / kg foodwhere it reached 64% in koi carps until the age of 3 months. Total length was thesingle trait that registered significant differences (p0.01 and p0.05 whencomparisons among control and all the other experimental variants were made. Thissuggests that TU treatment significantly reduced length growing of the carps even itwas administered in dose of 30, 60 or 90 mg / kg food. Supplementation of food withTU modified sex ratio in studied fishes.

  19. Dietary supplementation of l-arginine and chromium picolinate in sows during gestation affects the muscle fibre characteristics but not the performance of their progeny.

    Science.gov (United States)

    Shi, Zhan; Song, Wentao; Sun, Yuecheng; Wang, Liansheng; Shi, Baoming; Shan, Anshan; Bi, Zhongpeng

    2018-01-01

    The present study investigated the effects of dietary supplementation of l-arginine and chromium picolinate (CrP) in sows during gestation on muscle fibre characteristics, performance and carcass characteristics of their progeny. Sixty healthy sows were randomly divided into four groups as a 2 × 2 factorial experiment design: one group received the control diet, another received the control diet + 10 g kg(-1) l-arginine, the third group received the control diet + 400 ppb CrP, and the fou