Sex Ratio: The number of males per 100 females.Sex Factors: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.Sex Determination Processes: The mechanisms by which the SEX of an individual's GONADS are fixed.Sex Characteristics: Those characteristics that distinguish one SEX from the other. The primary sex characteristics are the OVARIES and TESTES and their related hormones. Secondary sex characteristics are those which are masculine or feminine but not directly related to reproduction.Sex Determination Analysis: Validation of the SEX of an individual by inspection of the GONADS and/or by genetic tests.Sex Preselection: Methods for controlling genetic SEX of offspring.Reproduction: The total process by which organisms produce offspring. (Stedman, 25th ed)Wasps: Any of numerous winged hymenopterous insects of social as well as solitary habits and having formidable stings.Sex Chromosomes: The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Hymenoptera: An extensive order of highly specialized insects including bees, wasps, and ants.Sex: The totality of characteristics of reproductive structure, functions, PHENOTYPE, and GENOTYPE, differentiating the MALE from the FEMALE organism.Birth Rate: The number of births in a given population per year or other unit of time.Sexual Behavior, Animal: Sexual activities of animals.Competitive Behavior: The direct struggle between individuals for environmental necessities or for a common goal.Sex Differentiation: The process in developing sex- or gender-specific tissue, organ, or function after SEX DETERMINATION PROCESSES have set the sex of the GONADS. Major areas of sex differentiation occur in the reproductive tract (GENITALIA) and the brain.Paternal Exposure: Exposure of the male parent, human or animal, to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals that may affect offspring.Wolbachia: A genus of bacteria comprised of a heterogenous group of gram-negative small rods and coccoid forms associated with arthropods. (From Bergey's Manual of Systematic Bacteriology, vol 1, 1984)Fertility: The capacity to conceive or to induce conception. It may refer to either the male or female.Litter Size: The number of offspring produced at one birth by a viviparous animal.Sex Distribution: The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Unsafe Sex: Sexual behaviors which are high-risk for contracting SEXUALLY TRANSMITTED DISEASES or for producing PREGNANCY.Disorders of Sex Development: In gonochoristic organisms, congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Effects from exposure to abnormal levels of GONADAL HORMONES in the maternal environment, or disruption of the function of those hormones by ENDOCRINE DISRUPTORS are included.Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Nesting Behavior: Animal behavior associated with the nest; includes construction, effects of size and material; behavior of the adult during the nesting period and the effect of the nest on the behavior of the young.Population Dynamics: The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population.Y Chromosome: The male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans and in some other male-heterogametic species in which the homologue of the X chromosome has been retained.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Birth Order: The sequence in which children are born into the family.Sex Workers: People who engage in occupational sexual behavior in exchange for economic rewards or other extrinsic considerations.Oviposition: The process of laying or shedding fully developed eggs (OVA) from the female body. The term is usually used for certain INSECTS or FISHES with an organ called ovipositor where eggs are stored or deposited before expulsion from the body.AzerbaijanEndocrinology: A subspecialty of internal medicine concerned with the metabolism, physiology, and disorders of the ENDOCRINE SYSTEM.Government PublicationsSeasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Government Publications as Topic: Discussion of documents issued by local, regional, or national governments or by their agencies or subdivisions.GeorgiaTemperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Selection, Genetic: Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.Drosophila: A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.Suppression, Genetic: Mutation process that restores the wild-type PHENOTYPE in an organism possessing a mutationally altered GENOTYPE. The second "suppressor" mutation may be on a different gene, on the same gene but located at a distance from the site of the primary mutation, or in extrachromosomal genes (EXTRACHROMOSOMAL INHERITANCE).Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Drosophila melanogaster: A species of fruit fly much used in genetics because of the large size of its chromosomes.Drosophila Proteins: Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.Environmental Medicine: Medical specialty concerned with environmental factors that may impinge upon human disease, and development of methods for the detection, prevention, and control of environmentally related disease.Occupational Medicine: Medical specialty concerned with the promotion and maintenance of the physical and mental health of employees in occupational settings.Petroleum: Naturally occurring complex liquid hydrocarbons which, after distillation, yield combustible fuels, petrochemicals, and lubricants.Gas, Natural: A combustible, gaseous mixture of low-molecular weight PARAFFIN hydrocarbons, generated below the surface of the earth. It contains mostly METHANE and ETHANE with small amounts of PROPANE; BUTANES; and higher hydrocarbons, and sometimes NITROGEN; CARBON DIOXIDE; HYDROGEN SULFIDE; and HELIUM. (from McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Extraction and Processing Industry: The industry concerned with the removal of raw materials from the Earth's crust and with their conversion into refined products.Ericaceae: The heath plant family of the order Ericales, subclass Dilleniidae, class Magnoliopsida that are generally shrubs or small trees. Leaves are alternate, simple, and leathery; flowers are symmetrical with a 4- or 5-parted corolla of partly fused petals.Indians, North American: Individual members of North American ethnic groups with ancient historic ancestral origins in Asia.Manitoba: A province of Canada, lying between the provinces of Saskatchewan and Ontario. Its capital is Winnipeg. Taking its name from Lake Manitoba, itself named for one of its islands, the name derived from Algonquian Manitou, great spirit. (From Webster's New Geographical Dictionary, 1988, p724 & Room, Brewer's Dictionary of Names, 1992, p332)United Nations: An international organization whose members include most of the sovereign nations of the world with headquarters in New York City. The primary objectives of the organization are to maintain peace and security and to achieve international cooperation in solving international economic, social, cultural, or humanitarian problems.IndiaAsia: The largest of the continents. It was known to the Romans more specifically as what we know today as Asia Minor. The name comes from at least two possible sources: from the Assyrian asu (to rise) or from the Sanskrit usa (dawn), both with reference to its being the land of the rising sun, i.e., eastern as opposed to Europe, to the west. (From Webster's New Geographical Dictionary, 1988, p82 & Room, Brewer's Dictionary of Names, 1992, p34)
1 sex ratio indicative of worker colony control. B. terrestris often does not conform to standard predictions of sex ratios ... resulting in an overall sex ratio of 1:4 (female to males). However, most studies show that this balance of bimodal sex ... Sex ratios. Due to the variability in the switch point to male production from worker production of B. terrestris ... Late-switching colonies have fewer males and a more even sex ratio of 1:1:3, thus indicating the queen's control over her ...
"Sex ratios". Population Statistics Unit, Statistics New Zealand Statistics House. "Sex Ratio". The World Factbook. CIA. ... "Ethnic group (detailed single and combination) by age group and sex, for the census usually resident population count, 2013 (RC ... For urban areas, "Subnational population estimates (UA, AU), by age and sex, at 30 June 1996, 2001, 2006-16 (2017 boundary)". ... "QuickStats About Incomes: Personal Income by Sex". New Zealand Statistics. Retrieved 9 May 2011. "QuickStats About Incomes: ...
"Sex Ratio". The World Factbook. Chen, Martha, Joann Vanek, Francie Lund, James Heintz, Renana Jhabvala, and Christine Bonner. ... These ratios are compiled and published by the World Economic Forum. The median annual income for female workers in the United ... Generally speaking, the closer the ratio is to 1, the more gender equal an economy is because neither sex has a ... Table 3: Ratio of Female-to-Male Workers Source: Global Gender Gap Report 2012, World Economic Forum Similar to the ratio of ...
Dependency ratios. total dependency ratio: 52.6 (2015 est.). youth dependency ratio: 43 (2015 est.). elderly dependency ratio: ... Sex ratio. Age. Ratio. (males/females) Total:. 1.02 At birth:. 1.07 ... potential support ratio: 10.5 (2015 est.). Life expectancy at birth. total population: 76.2 years. male: 73.2 years. female: ...
8.12 Dependency ratios. *8.13 Urbanization. *8.14 Sex ratio. *8.15 Infant mortality rate ... Dependency ratios. total dependency ratio: 84.5 (2015 est.). youth dependency ratio: 78.3 (2015 est.). elderly dependency ... Sex ratio. at birth: 1.02 male(s)/female. 0-14 years: 1.02 male(s)/female. 15-24 years: 1 male(s)/female. 25-54 years: ... potential support ratio: 16.1 (2015 est.). Urbanization. urban population: 66.9% of total population (2018). rate of ...
In most species that deviate from a 1:1 sex ratio, there is a degree of sexual dimorphism, with the more common sex being ... Robert A. Metcalf argues that data on the skewed sex ratios does not prove or disprove the hypothesis of parent-offspring ... 1 male to female sex ratio. Despite the equal parental investment in the sexes, the average frequency for females in Polistes ... In a population that has a female biased sex ratio, according to W. D. Hamilton, there could be Local Mate Competition, or LMC ...
1 sex-ratio production proves the best overall genotypic strategy". "In the way in which the success of a chosen sex ratio ... Hamilton in his 1967 paper on sex ratios in Science. In this paper Hamilton discusses sex ratios as strategies in a game, and ... This is exactly the case with the "unbeatable" sex ratios referred to." Hamilton (1967). "[...] But if, on the contrary, ... ISBN 0-8014-1319-2. Edwards, A.W.F. (1998). "Natural selection and the sex ratio: Fisher's sources". American Naturalist. 151 ( ...
1:1 sex ratio. Fisher's principle outlines why almost all species using sexual reproduction have a sex ratio of 1:1. W. D ... "Extraordinary sex ratios". Science. 156 (3774): 477-488. Bibcode:1967Sci...156..477H. doi:10.1126/science.156.3774.477. PMID ... Many ectothermic vertebrates have no sex chromosomes. If they have different sexes, sex is determined environmentally rather ... For example, female birds, snakes, and butterflies have ZW sex chromosomes, and males have ZZ sex chromosomes. ...
Sex ratio theory. Operational sex ratio is the number of sexually competing males versus the number of sexually competing ... High sex ratios indicate that there are more men than women available, while low sex ratios imply more women than men are ... Low sex ratios (more women) are correlated with more unrestricted sociosexuality, as men can afford to demand more casual sex ... High sex ratios (more men) are associated with lower SOI scores (more restricted sociosexual orientation), as men must satisfy ...
Dependency ratiosEdit. total dependency ratio: 100.2 (2015 est.). youth dependency ratio: 95.2 (2015 est.). elderly dependency ... Sex ratioEdit. At birth: 1.04 male(s)/female. Under 15 years: 1.01 male(s)/female. 15-64 years: 0.92 male(s)/female. 65 years ... potential support ratio: 20.3 (2015 est.). Contraceptive prevalence rateEdit. 5.7% (2014/15). UrbanizationEdit. urban ...
Sex ratioEdit. Recent studies have shown a shift in Vietnam's sex ratio to match that of other countries in the region, where ... 283-302; Daniel Goodkind, "Rising Sex Ratios at Birth in Confucian Asia: A Summary of Interpretive Puzzles" (Unpublished ... In 2006, the sex ratio was found to be 110 men per 100 women throughout Vietnam, higher than the established normal sex ratio ... Zeng Yi et al., "Causes and Implications of the Recent Increase in the Reported Sex Ratio of Birth in China," Population and ...
Sex ratioEdit. Apart from some eusocial wasps, organisms which reproduce sexually have a 1:1 sex ratio of male and female ... "Extraordinary sex ratios". Science. 156 (3774): 477-488. Bibcode:1967Sci...156..477H. doi:10.1126/science.156.3774.477. PMID ... As the 1:1 sex ratio is approached, the advantage associated with producing males dies away. ... Also in some species each plant is one sex while other species produce both sexes on the same plant. ...
Sex ratio: at birth: male(s)/female 1.0500 1.01 1.0424 1.0310 Sex ratio: under 15 years: male(s)/female 1.0408 n.a. 1.0153 ... After a decline in enrollment ratios during the transition to a market economy in the 1990s, school attendance is now once more ... Sex ratio: 60 years and over: male(s)/female 0.8169 0.80 n.a. 0.7933 ... Sex ratio: 15-59 years: male(s)/female 1.0003 n.a. 0.9414 0.9379 ... Sex ratio: total population: male(s)/female 1.0002 0.9947 n.a. ...
... sex-ratio bias ... and the ratios among the major nutrients are helpful guides to ...
... one population in Ontario has a female to male ratio of 4:1. Hatchling sex ratio varies based on egg temperature. During ... Adult sex ratios of painted turtle populations average around 1:1. Many populations are slightly male-heavy, but some are ... Adults outnumber juveniles in most populations, but gauging the ratios is difficult because juveniles are harder to catch; with ... It does not appear that females choose nesting sites to influence the sex of the hatchlings; within a population, nests ...
Edwards, A.W.F. (1998). "Natural Selection and the Sex Ratio: Fisher's Sources". American Naturalist. 151 (6): 564-569. doi: ... Nelder (1990) described continuous counts, continuous ratios, count ratios, and categorical modes of data. See also ... Ratio measurements have both a meaningful zero value and the distances between different measurements defined, and permit any ... The psychophysicist Stanley Smith Stevens defined nominal, ordinal, interval, and ratio scales. Nominal measurements do not ...
Hamilton WD (April 1967). "Extraordinary sex ratios. A sex-ratio theory for sex linkage and inbreeding has new implications in ... producing an extremely male-biased sex ratio. In ecologically challenged species, such biased sex ratios imply that the ... When segregation distortion acts on sex chromosomes, they can skew the sex ratio. The SR system in Drosophila pseudoobscura, ... Whenever sex chromosomes undergo segregation distortion, the population sex ratio is altered, making these systems particularly ...
Unbalanced sex-ratios were more likely to occur in slow-growing populations. ... One key natural factor affecting the seal populations is the male-biased sex-ratio, which results in increased aggressive ... and subsequent skewed gender ratios. Anthropogenic or human impacts include hunting (during the 1800s and 1900s) and the ... Smaller populations were more likely to experience mobbing as a result of the higher male/female ratio and male aggression. ...
Sex ratio distortionsEdit. Certain kinds of IVF, in particular ICSI (first applied in 1991) and blastocyst transfer (first ... can lead to intentional or unintentional demographic effects such as the skewed live-birth sex ratios seen in communist China ... This can be used to diagnose monogenic disorders with sex linkage. It can potentially be used for sex selection, wherein a ... Standard IVF done at the second or third day leads to a normal sex ratio. ...
... under Varying Operational Sex Ratios". Ethology. 102 (2): 304-322. doi:10.1111/j.1439-0310.1996.tb01127.x.. ... as well as the operational sex ratio (OSR) of the environment. ... "Size- and Sex-Selective Mortality of Adult Sockeye Salmon: Bears, Gulls, and Fish Out of Water". Transactions of the American ...
"Finger-length ratios show evidence of prenatal hormone-transfer between opposite-sex twins". Hormones and Behavior. 49 (3): 315 ... Medland, S.E.; Loehlin, J.C.; Martin, N.C. (2008). "No effect of prenatal hormone transfer on digit ratio in a large sample of ... Studies involving humans often compare opposite-sex to same-sex dizygotic twins. Females of opposite-sex twin pairs are thought ... Cohen-Bendahan CC, van de Beek C, Berenbaum SA (2005b). "Prenatal sex hormone effects on child and adult sex-typed behavior: ...
Hönekopp J, Watson S. Meta-Analysis of Digit Ratio 2D:4D Shows Greater Sex Difference in the Right Hand. „American Journal of ... A Critical Re-Evaluation of the Association Between 2D:4D Ratios and Fluctuating Asymmetry in Humans. „Annals of Human Biology ... Voracek M, Pietschnig J, Nader IW, Stieger S. Digit Ratio (2D:4D) and Sex-Role Orientation: Further Evidence and Meta-Analysis ... a b c d e f g h i j k l m n Manning JT, Kilduff L, Cook C, Crewther B, Fink B. Digit Ratio (2D:4D): A Biomarker for Prenatal ...
... the ratio of relatedness between sexes determines the sex investment ratios. As a result, it has been observed that there ... 1 sex ratio. Both the queen and the workers try to bias the sex ratio in their favor. In some species, the workers gain ... The sex-ratio conflict arises from a relatedness asymmetry, which is caused by the haplodiploidy nature of Hymenoptera. For ... Examples include the sex-ratio conflict and worker policing seen in certain species of social Hymenoptera such as ...
Peer, K.; Taborsky, M. (2004). "Female ambrosia beetles adjust their offspring sex ratio according to outbreeding opportunities ... and ants can modify sex ratios within colonies which maximizes relatedness among members and generates a workforce appropriate ... Shared gene proportions in haplo-diploid sex-determination system relationships Sex Daughter Son Mother Father Full sister Full ... In an X0 sex-determination system, males and females receive an equal number of autosomes, but when it comes to sex chromosomes ...
Göth, Anne (2007). "Incubation temperatures and sex ratios in Australian brush-turkey (Alectura lathami) mounds". Austral ... "Temperature-dependent sex ratio in a bird". Biology Letters. 1: 31-3. PMC 1629050 . PMID 17148121. doi:10.1098/rsbl.2004.0247. ... Birds have two sexes: either female or male. The sex of birds is determined by the Z and W sex chromosomes, rather than by the ... These birds do not exhibit temperature-dependent sex determination, but temperature-dependent sex mortality. ...
... such as risk of death or sex ratio) of a given age cohort within a population. Age and sex are crucial variables in the ... Isotope ratios in food, especially plant food, are directly and predictably reflected in bone chemistry, allowing researchers ... In reviewing the sexing of Egyptian skulls from Qua and Badari, Mann found that 20.3% could be assigned to a different sex than ... Sex-based differences are not inherently a form of inequality, but become an inequality when members of one sex are given ...
... also found that both sexes were more polygamous when the ratio was skewed towards the opposite sex. ... Researchers found that when the sex ratio was skewed, divorce and infidelity was more common. (Credit: O. Kruger). A joint ... "We found that a female bias in sex ratio destabilises the pair bond system, although it is unclear as to whether this is due to ... Bird mating behaviour influenced by sex ratios. Birds in female-dominated populations are more likely to ditch and divorce ...
... analogous to Fisherian sex ratio selection, that favours increased parental investment by whichever sex faces more intense ... We emphasize the need to distinguish between the ASR and the operational sex ratio (OSR). If mortality is higher when caring ... The second argument takes the reasonable premise that anisogamy produces a male-biased operational sex ratio (OSR) leading to ... Conventional sex roles imply caring females and competitive males. The evolution of sex role divergence is widely attributed to ...
Most animal sex ratios are 50:50. But that ratio can be changed by environmental factors like temperature or even by seasonal ... "Sex ratios are not necessarily tied to socioeconomic status or natural disasters, as those are always changing. There are all ... What her first-ever global analysis on birth sex ratio shows is that people living in areas with longer, darker winters - such ... Navara is currently studying the cues that affect the sex ratios in poultry. ...
In the absence of manipulation, both the sex ratio at birth and the population sex ratio are remarkably constant in human ... has distorted these natural sex ratios in large parts of Asia and North Africa. This son preference is manifest in sex- ... Abnormal sex ratios in human populations: Causes and consequences. Therese Hesketh and Zhu Wei Xing ... Measures to reduce sex selection must include strict enforcement of existing legislation, the ensuring of equal rights for ...
For these models, we calculated odds ratios (ORs) (i.e., the ratio of 2 odds or 2 male:female ratios). To account for small ... An increase in the sex ratio of births to India-born mothers in England and Wales: evidence of sex-selective abortion. Popul ... Sex ratios at birth after induced abortion. Marcelo L. Urquia, Rahim Moineddin, Prabhat Jha, Patricia J. OCampo, Kwame ... Sex ratios at birth after induced abortion. Marcelo L. Urquia, Rahim Moineddin, Prabhat Jha, Patricia J. OCampo, Kwame ...
Determinants of imbalanced sex ratio at birth in Nepal: evidence from secondary analysis of a large hospital-based study and ... Sex ratios at birth after induced abortion. Marcelo L. Urquia, Rahim Moineddin, Prabhat Jha, Patricia J. OCampo, Kwame ... Sex ratios at birth after induced abortion. Marcelo L. Urquia, Rahim Moineddin, Prabhat Jha, Patricia J. OCampo, Kwame ... Sex ratios at birth after induced abortion. Marcelo L. Urquia, Rahim Moineddin, Prabhat Jha, Patricia J. OCampo, Kwame ...
Hamilton W.D. (April 1967). "Extraordinary sex ratios. A sex-ratio theory for sex linkage and inbreeding has new implications ... primary sex ratio - ratio at fertilization secondary sex ratio - ratio at birth tertiary sex ratio - ratio in sexually mature ... Evolution of sex Operational sex ratio Sex allocation Trivers-Willard hypothesis XY sex-determination system Humans: Human sex ... The theory of sex ratio is a field of study concerned with the accurate prediction of sex ratios in all sexual species, based ...
Furthermore, the theory suggests that East German birth sex ratios should generally be lower than the observed sex ratio in ... Intersex § Population figures Operational sex ratio Sex selection Sex-selective abortion and infanticide Surplus women XY sex- ... High birth sex ratios, some claim, may be caused in part by social factors. Reported sex ratios at birth, outside the typical ... "Sex ratio at birth (per 100 female newborn, 2005-2010 data)". United Nations Data Division. "Trend Analysis of the Sex Ratio at ...
Im not evolutionary biologist, but, in humans, isnt the long run consequence of a male biased sex-ratio an equal sex ratio. ... The sex ratio imbalance during the California Gold Rush was very brief. Most of the Forty-Niners failed to find much gold, gave ... The long-run consequences of male-biased sex ratios. by Tyler Cowen June 11, 2018 at 12:32 am in *Data Source ... In areas with more male-biased sex ratios, women were historically more likely to get married and less likely to work outside ...
When the balance of the sexes is skewed towards one gender, parents are more likely to split up, leaving the father to care for ... He said: "We found that the chicks had a 50:50 sex ratio at hatching in all these species, and that the skewed adult sex ratios ... adult sex ratio bias can alter social behaviour with divorce, infidelity, and parental antagonism being more common in sex- ... Skewed sex ratios causes single fathers to bring up the young A new study from an international team of researchers finds that ...
This paper proposes a new competitive saving motive: As the sex ratio rises, Chinese parents with a son raise their savings in ... The Competitive Saving Motive: Evidence from Rising Sex Ratios and Savings Rates in China. Shang-Jin Wei, Xiaobo Zhang. NBER ... "The Competitive Saving Motive: Evidence from Rising Sex Ratios and Savings Rates in China," Journal of Political Economy, ...
For instance, high sex ratios at birth in some Asian countries are now attributed to sex-selective abortion and infanticide due ... Interesting observations about People , Sex ratio , Total population. *Qatar ranked first for sex ratio , total population ... Sex ratio at birth has recently emerged as an indicator of certain kinds of sex discrimination in some countries. ... Australia ranked first for sex ratio , total population amongst High income OECD countries in 2013. ...
... but its possible the heterogametric sex may have a lower chance of surviving to adulthood. ... but its possible the heterogametric sex may have a lower chance of surviving to adulthood. ... Sex chromosomes may be involved in skewing sex ratios, ... Sex chromosomes may be involved in skewing sex ratios, ... Heterogamety may play a natural role in sex selection, but unnatural causes can also skew a species sex ratio. For instance, ...
In every census since 1951, the two ratios have gone more or less hand in hand, dropping steadily except in the late 1970s (see ... TABLE 1: Child Sex RAtio (CSR) and Overall Sex Ratio (OSR) 1951 1961 1971 1981 1991 2001 ... However, during the same decade, the Overall Sex Ratio (OSR, which looks at the ratio of all females to males, and not just ... Sex ratio: the hidden horrors Millions of males are falling victim to illnesses at much faster rates, skewing the demographic ...
Influence of latent toxoplasmosis on the secondary sex ratio in mice - Volume 134 Issue 12 - Š. KAŇKOVÁ, P. KODYM, D. FRYNTA, R ... Hamilton, W. D. (1967). Extraordinary sex ratios. Science 156, 477-478.. Hostomská, L., Jírovec, O., Horáčková, M. and Hrubcová ... The sex ratio may be influenced by many factors, such as stress and immunosuppression, age of parents, parity and sex of ... Therefore, we speculate that Toxoplasma can alter the secondary sex ratio (i.e. male to female ratio in the offspring) of ...
... "sex-ratio distorters" and the phenotype of skewed progeny sex ratios is termed "sex-ratio." The mere transmission advantage of ... Hamilton, W. D., 1967 Extraordinary sex ratios. A sex-ratio theory for sex linkage and inbreeding has new implications in ... Selection on the Winters sex-ratio is older than on the Paris sex-ratio, the other system in D. simulans that has been ... If we apportion fitness evenly among individuals of each sex, the fitness of each male is then simply equal to the sex ratio, W ...
Sex ratio is the number of males for each female. Current world sex ratio at birth: 1.07:1 male(s)/female (107 baby boys to 100 ... Sex ratio at birth has recently emerged as an indicator of cer ... This map shows worldwide human sex ratio at birth. ... For instance, high sex ratios at birth in some Asian countries are now attributed to sex-selective abortion and infanticide due ... Sex ratio is the number of males for each female.. Current world sex ratio at birth: 1.07:1 male(s)/female (107 baby boys to ...
Ambient temperature predicts sex ratios and male longevity. Ralph Catalano et al.. Abstract. The theory that natural selection ... we find that cold ambient temperatures during gestation predict lower secondary sex ratios and longer life span of males in ... by which women subjected to environmental stressors abort frail male fetuses implies that climate change may affect sex ratio ...
These authors cited a study of Yang and colleagues2 of sex ratios near a petroleum refinery plant in Taiwan. In that study Yang ... Saadat and colleagues1 reported a significantly high sex ratio (proportion male) in births to people exposed to oil and natural ... Yang and colleagues3 contrasted the sex ratios at birth in 16 municipalities in which there was substantial involvement in the ... petrochemical industry with sex ratios in the other 345 municipalities in Taiwan. Overall, the offspring sex ratios of the ...
... the conjunction of sex hormone deficiency and alcoholic diet (G1 and G7) led to the lowest Ca/P ratios for both females and ... the deficiency of sex hormones did not change the Ca/P ratio in females or males. However, the combination of sex hormone ... the deficiency of sex hormones did change the Ca/P ratio in females and males. However, the deficiency of sex hormones in ... This was verified by the results observed in ad libitum groups in which sex hormone deficiency did not alter Ca/P ratio in both ...
In plovers, closely related populations express strikingly different adult sex ratios. This variation is mainly driven by sex ... The behavioural scientist did his research about the sex ratio of plovers supervised by Professor Dr. Joseph Hoffman and ... Families in populations with biased adult sex ratios were predominantly tended by a single parent - typically the father - ... Population sex ratio influences parental care in plovers. « One exhibition at... , Startseite , New Agreement signed... » ...
First, rising sex ratios in India have been recorded since the early 1980s, and have since continued increasing with no sign, ... Inicio Characteristics of Sex-Ratio Imbalance in India, and Future Scenarios. Characteristics of Sex-Ratio Imbalance in India, ... Second, even if sex-ratio values in India are still beneath those of China, its potential contribution to the overall " ... weight.1 The prospect of further worsening of Indias sex composition requires close monitoring of current sex-ratio trends in ...
Population-wide sex ratios and sex-specific mortality did not differ from parity, but clutch size, mass of the father, maternal ... We investigated whether hatching and fledging sex ratio and sex-specific chick mortality correlated with the ecological ... Sex ratio adjustments in common terns: influence of mate condition and maternal experience. Authors. *. María M. Benito,. * ... Artur Goławski, Zbigniew Kasprzykowski, Mateusz Ledwoń, Emilia Mróz, Federico Morelli, Brood sex ratio in expansive and non- ...
Genus Salixis a notable example of the female-biased sex ratio. Quite surprisingly, there are very few studies retesting... ... 1 sex ratios. Genus Salix is a notable example of the female-biased sex ratio. Quite surprisingly, there are very few studies ... Female-biased sex ratio despite the absence of spatial and niche segregation between sexes in alpine populations of dioecious ... Alström-Rapaport C, Lascoux M, Gullberg U (1997) Sex determination and sex ratio in the dioecious shrub Salix viminalis L. ...
We also argue that extremely female-biased sex ratios of the host species, combined with overall sex ratio parity in the ... Sex allocation has been studied for very few inquilines of social Hymenoptera. Here we report sex ratio patterns in the ... Sex Ratios in a Socially Parasitic Bee and Implications for Host-Parasite Interactions. *Nahid Shokri Bousjein. 1. , ... Shokri Bousjein, N., Staines, M., Vo, C. et al. Sex Ratios in a Socially Parasitic Bee and Implications for Host-Parasite ...
FemalesChromosomesAverage sex ratioSecondary sex ratioAbstractPopulationsEvolution ofImbalanced sex ratios at birthSpeciesAllocationPredictsEqual sex ratiosNormal sex ratio2017VariationBiasImbalance1978Reduce sex selectionHigh sexAffect sexHigher sexDifferences in sexEvolutionarily stable s1967Overall sexReproductiveDeterminationDemographicBiasesBirth sexCommon sexRarer sexShiftsConsequencesAbortionsBoys to 100 girlsMortalityDeviationsSegregationAnalysesParityManipulationIndiaOperational sex r1988Adaptive19971992ProportionFlour BeetlesParentalHatchlingsAbsenceHuman societies1991Distortions
- We found that a female bias in sex ratio destabilises the pair bond system, although it is unclear as to whether this is due to lots of unpaired females luring males away from their mate or if the male, given a greater choice of partners, decides to switch partners more frequently. (bath.ac.uk)
- Conventional sex roles imply caring females and competitive males. (nih.gov)
- The sex ratio is the ratio of males to females in a population. (wikipedia.org)
- A study performed by Danforth observed no significant difference in the number of males and females from the 1:1 sex ratio. (wikipedia.org)
- Sex-ratio of adult populations of pelagic copepods is usually skewed towards dominance of females. (wikipedia.org)
- In anthropology and demography, the human sex ratio is the ratio of males to females in a population. (wikipedia.org)
- The sex ratio for the entire world population is 101 males to 100 females. (wikipedia.org)
- Human sex ratios, either at birth or in the population as a whole, are reported in any of four ways: the ratio of males to females, the ratio of females to males, the proportion of males, or the proportion of females. (wikipedia.org)
- This article uses the ratio of males to females, unless specified otherwise. (wikipedia.org)
- Consequently, the sex ratio tends to reduce as age increases and among the elderly there is usually a greater proportion of females. (wikipedia.org)
- Whilst three populations of plover had a balance in the sex ratio of males to females and shared parenting of their offspring, the scientists found that in populations where there were more males than females, or vice versa, the parenting roles shifted leaving the males to look after the chicks. (eurekalert.org)
- The sex ratio of a species defines the proportion of males to females. (mercola.com)
- In this case, the females are the heterogametic sex. (mercola.com)
- However, during the same decade, the Overall Sex Ratio (OSR, which looks at the ratio of all females to males, and not just those in the 0-6 age group) recorded its highest gain, rising 6 points from 927 to 933. (indiatogether.org)
- The number of females would have been even higher (and thus improved the sex ratio even more) if nature had been allowed to take its course. (indiatogether.org)
- Therefore, we speculate that Toxoplasma can alter the secondary sex ratio (i.e. male to female ratio in the offspring) of infected females to increase the proportion of (congenitally infected) male offspring, which are the more migratory sex in most rodent species. (cambridge.org)
- In the later phase of infection, mice with congenital toxoplasmosis had a lower sex ratio than controls, which is in accord with the Trivers-Willard hypothesis of sex ratio manipulation, suggesting that females in poor physical condition give birth to more female offspring. (cambridge.org)
- Consumption of alcohol reduced the Ca/P ratio in both females and males. (hindawi.com)
- The isocaloric diet reduced the Ca/P ratio in females. (hindawi.com)
- In groups with the ad libitum diet, the deficiency of sex hormones did not change the Ca/P ratio in females or males. (hindawi.com)
- However, the combination of sex hormone deficiency and alcoholic diet presented the lowest values for the Ca/P ratio in both females and males. (hindawi.com)
- The ratio of adult males and females is an important demographic trait in wild populations. (uni-bielefeld.de)
- Males were generally taller than females, suggesting that a different allocation of resources may occur in both sexes. (springer.com)
- Additionally, no differences in spatial sex segregation and microhabitat preferences were found between males and females at a fine scale within the studied populations. (springer.com)
- This article studies the relationship between sex ratio at Birth (males per females) of USA and the Chinese Baby Gender Prediction Chart to help American women to choose desired gender for their next babies. (chinesefortunecalendar.com)
- The US sex ratio between males and females is 1.048 . (chinesefortunecalendar.com)
- 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. (biomedcentral.com)
- Well, the sex ratio at birth in the United States, as in Britain, is 105, meaning 105:100, or 105 males born for every 100 females. (typepad.com)
- The dioecy model provides a comprehensive framework for sex allocation that is based on the pay-offs to the colony via production of males and females, and is independent of the genetic variation among colonies. (royalsocietypublishing.org)
- 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. (scielo.br)
- 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. (flutrackers.com)
- Differential mortality in females resulted in a strongly male-skewed sex ratio in the most contaminated areas. (flutrackers.com)
- 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. (flutrackers.com)
- 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. (flutrackers.com)
- 2 The male to female ratio of live births is generally expressed as the ratio of male live births divided by total live births (M/F), and the human M/F is expected to be 0.515, with approximately 3% more males born than females. (bmj.com)
- Sex ratios can also influence the sexual and reproductive fitness of males and females (Michalczyk, ?ukasz 2011). (k-state.edu)
- the ratio between the toxic effects of a substance on adults (humans or animals, especially pregnant females) and such effects on developing embryos or fetuses. (thefreedictionary.com)
- 2. the ratio of the numbers of males to females affected by a particular disease or trait. (thefreedictionary.com)
- The distribution at birth is usually 106 boys to 100 girls, but the ratio shifts in adulthood, so that, because men have a lower life expectancy, the proportion of females is greater. (thefreedictionary.com)
- In fact, in humans there are often slightly more males born than females (105:100 is typical) due either to preferential fertilization of eggs by Y-carrying sperm causing an unequal primary ratio or to preferential survival of males during GESTATION . (thefreedictionary.com)
- In fish exposed to TC, sex determination occurred earlier, because 90% of soles were males/females at 110 DPH, whereas 45% of fish under CT were undifferentiated at that time. (stir.ac.uk)
- Regarding sex ratio, juveniles exposed to TC showed a higher proportion of females than fish under CT or constant temperature. (stir.ac.uk)
- Females mating with high quality males should, therefore, be expected to produce brood sex ratios biased towards sons, as male offspring would receive a relatively greater advantage from inheritance of their father's characteristics than would their female siblings. (lancs.ac.uk)
- This suggests that females in our population were either unable to manipulate offspring sex allocation or did not do so because selection pressures were not strong enough to produce a significant shift away from random sex allocation. (lancs.ac.uk)
- Theoretical models propose that the adjustment of offspring sex ratio by females may pre-dispose the evolution of monogeny in gall midges however empirical studies in this field are superficial. (eje.cz)
- Research was conducted to identify possible treatments that stimulate hens to skew sex ratios to produce more females than males in commercial layers. (poultryworld.net)
- The operational sex ratio (OSR), the ratio of sexually active males to sexually receptive females, is one of the main measures used to predict the intensity and direction of mating competition, influencing the opportunity for sexual selection. (concordia.ca)
- We manipulated OSR on two levels in two enclosures, a female biased treatment (3♂:6♀ = OSR 0.5) and a sex balanced treatment (3♂:3♀ = OSR 1), over two years with males from two age groups (1.5 or 2.5-years-old), and with females of various ages. (concordia.ca)
- The WHO states that abdominal obesity is defined as a waist-hip ratio above 0.90 for males and above 0.85 for females, or a body mass index (BMI) above 30.0. (wikipedia.org)
- Normally we understand the (near) 50-50 male/female population sex ratio with this simple model: if there were more males than females then individuals who are genetically disposed to have female children will have more grandchildren because their female children will find more mates. (cheaptalk.org)
- To survive, a driver must maintain tight linkage with an insensitive target locus lest it drive against itself, a condition ensured by the lack of recombination between sex chromosomes ( C harlesworth and H artl 1978 ). (genetics.org)
- Charlesworth D (2016) Plant sex chromosomes. (springer.com)
- The ratio is controlled by the SEGREGATION of SEX CHROMOSOMES in the HETEROGAMETIC SEX during MEIOSIS (see SEX DETERMINATION ). (thefreedictionary.com)
- BULL J.J. 1983: The Evolution of Sex Chromosomes and Sex Determining Mechanisms. (eje.cz)
- The ability of fathers to bias offspring sex ratios has traditionally been dismissed given the expectation of an equal proportion of X- and Y-chromosome-bearing sperm (CBS) in ejaculates due to segregation of sex chromosomes at meiosis. (pacospace.com)
- It is generally divided into four subdivisions: primary sex ratio - ratio at fertilization secondary sex ratio - ratio at birth tertiary sex ratio - ratio in sexually mature organisms Also called adult sex ratio and abbreviated to ASR. (wikipedia.org)
- We have determined whether isolated subalpine populations of Salix lapponum exhibit a biased secondary sex ratio, measured the size of the plants, and tested the spatial and ecological correlations of the bias at fine and broad scales. (springer.com)
- In the absence of manipulation, both the sex ratio at birth and the population sex ratio are remarkably constant in human populations. (pnas.org)
- We first explain how some natural fluctuation in sex ratio occurs in human populations, and we illustrate this with the example of the effects of war. (pnas.org)
- Accurate figures for sex ratio at birth are difficult to obtain in many populations because of inadequacy of vital statistics registration ( 2 ). (pnas.org)
- In the absence of manipulation, the sex ratio at birth is remarkably consistent across human populations, with 105-107 male births for every 100 female births. (pnas.org)
- When the balance of the sexes is skewed towards one gender, parents are more likely to split up, leaving the father to care for the offspring, says a study from an international team of scientists studying bird populations. (eurekalert.org)
- By influencing mate availability, adult sex ratio bias can alter social behaviour with divorce, infidelity, and parental antagonism being more common in sex-biased populations. (eurekalert.org)
- So we wanted to look at what factors were related to imbalances in adult sex ratio of plover populations. (eurekalert.org)
- The researchers hope in the future to investigate the effects of sex ratio on social behaviour in other animal populations including humans. (eurekalert.org)
- In plovers, closely related populations express strikingly different adult sex ratios. (uni-bielefeld.de)
- Families in populations with biased adult sex ratios were predominantly tended by a single parent - typically the father - whereas in balanced populations, generally both parents take care of the young, suggesting that parental cooperation breaks down under an unbalanced sex ratio. (uni-bielefeld.de)
- In all six populations, the hatching sex ratio was balanced. (uni-bielefeld.de)
- The researchers found that the adult sex ratio in a population was tightly linked to parental cooperation: In unbiased populations, it was more likely that both parents worked together to care for the young, whereas in male- or female-biased populations, there were higher rates of single parent care. (uni-bielefeld.de)
- However, in populations where the conditions for the Boomsma-Grafen model hold, kin selection will still lead to an association between sex ratio and relatedness. (royalsocietypublishing.org)
- 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. (flutrackers.com)
- Deviation of sex ratios from unity in wild animal populations has recently been demonstrated to be far more prevalent than previously thought. (biomedcentral.com)
- We used a simulation model to examine the effects of dispersal, temperature-dependent juvenile survival and sex determining mechanism (temperature-dependent sex determination (TSD) and genotypic sex determination (GSD)) and their interactions, on range limits in populations extending across a continuous range of air temperatures. (edu.au)
- The study, which examined the pair bonding and mating behaviour of 197 different species of bird, found the divorce rate was higher in species with a female-biased sex ratio. (bath.ac.uk)
- Biased sex ratios may destabilise pair-bonds and increase marital infidelity, although relevance of these findings for other species need to be thoroughly tested. (bath.ac.uk)
- In most sexually reproducing species, the ratio tends to be 1:1. (wikipedia.org)
- For various reasons, however, many species deviate from anything like an even sex ratio, either periodically or permanently. (wikipedia.org)
- In most species, the sex ratio varies according to the age profile of the population. (wikipedia.org)
- The theory of sex ratio is a field of study concerned with the accurate prediction of sex ratios in all sexual species, based on a consideration of their natural history. (wikipedia.org)
- He defines five major questions, both for his book and the field in general (slightly abbreviated here): For a dioecious species, what is the equilibrium sex ratio maintained by natural selection? (wikipedia.org)
- Fisher's principle explains why for most species, the sex ratio is approximately 1:1. (wikipedia.org)
- This ratio has been observed in many species, including the bee Macrotera portalis. (wikipedia.org)
- For species where the cost of successfully raising one offspring is roughly the same regardless of its sex, this translates to an approximately equal sex ratio. (wikipedia.org)
- Bacteria of the genus Wolbachia cause skewed sex ratios in some arthropod species as they kill males. (wikipedia.org)
- More data are available for humans than for any other species, and the human sex ratio is more studied than that of any other species, but interpreting these statistics can be difficult. (wikipedia.org)
- Like most sexual species, the sex ratio in humans is approximately 1:1. (wikipedia.org)
- 1 Among other species, the ratios vary. (mercola.com)
- For instance, in bird species the more prevalent sex tends to be the one raising the offspring. (mercola.com)
- Heterogamety may play a natural role in sex selection, but unnatural causes can also skew a species' sex ratio. (mercola.com)
- Drosophila is the most extensively studied insect taxon, and sex-chromosome meiotic drive systems have been identified in more than a dozen species ( J aenike 2001 ). (genetics.org)
- Adaptive sex allocation has frequently been studied in sexually size dimorphic species, but far less is known about patterns of sex allocation in species without pronounced sexual size dimorphism. (wiley.com)
- Our results suggest lines for future studies on adaptive sex allocation in sexually nearly monomorphic species, where adjustment of sex ratio related to parental factors and differential allocation between the offspring may also occur. (wiley.com)
- We also argue that extremely female-biased sex ratios of the host species, combined with overall sex ratio parity in the parasite, may help ameliorate disparity in effective population sizes between these two species which are locked in an evolutionary arms race. (springer.com)
- We test predictions of the model with data from a long-term study of harvester ants, and show that it correctly predicts the intermediate sex ratios we observe in our study species. (royalsocietypublishing.org)
- Sex ratios in social insects have been the subject of intense study since Trivers & Hare (1976) first modified Fisher's (1930) sex ratio theory to include kin selection, particularly in species with haplodiploid sex determination. (royalsocietypublishing.org)
- For understanding driving factors for Collembola density and diversity this study investigated (1) trophic niche differentiation of Collembola species using stable isotope analysis, (2) mode of reproduction and sex ratios in the field, (3) colonization of new habitats by parthenogenetic and sexual species and (4) the genetic variation in parthenogenetic and sexual species in Europe. (tu-darmstadt.de)
- The sex ratios of Collembola species were assessed in a temperate oak-beech forest in two months intervals during one year. (tu-darmstadt.de)
- The sex ratio of bisexual Collembola species in the litter layer generally was more female biased than that in the mineral soil. (tu-darmstadt.de)
- Nonetheless, sexual differences are often observed in parasite species including dimorphism in size, mobility, behaviour, competitive ability, or even genetic structure [ 4 - 6 ], likely to result in sex-specific fitness maximisation strategies, similarly to their hosts. (biomedcentral.com)
- It is likely that the skewed sex ratio in most species of monogenous gall midges is a consequence of differential mortality of male and female progenies under harsh conditions. (eje.cz)
- Two-sex dispersal eliminated the influence of biased sex ratios on ranges.Conclusion: The results highlight the importance of the demographic parameter of sex ratio in determining population persistence and species range limits. (edu.au)
- The field continues to be heavily influenced by Eric Charnov's 1982 book, Sex Allocation. (wikipedia.org)
- Biological research mostly concerns itself with sex allocation rather than sex ratio, sex allocation denoting the allocation of energy to either sex. (wikipedia.org)
- Sex allocation has been studied for very few inquilines of social Hymenoptera. (springer.com)
- Aenmey TK, Tierney SM, Pillay N, Schwarz MP (2006) Nesting biology of an African allodapine bee Braunsapis vitrea: female biased sex allocation in the absence of worker-like behavioural castes. (springer.com)
- Bull NJ, Schwarz MP (2001) Brood insurance via protogyny: a source of female biased sex allocation. (springer.com)
- Sex allocation theory predicts that parents should manipulate brood sex ratio in order to maximise the combined reproductive value of their progeny. (lancs.ac.uk)
- Furthermore, it has been suggested that sex allocation in chicks fathered through extrapair fertilizations should also be biased towards sons. (lancs.ac.uk)
- We suggest that, in addition to the weakness of selection pressures, the possible mechanisms responsible for the allocation of sex may not be sufficiently accurate to control offspring sex at the level of the individual egg. (lancs.ac.uk)
- CHARNOV E.L. 1982: The Theory of Sex Allocation. (eje.cz)
- Sex ratio allocation has important fitness consequences, and theory predicts that parents should adjust offspring sex ratio in cases where the fitness returns of producing male and female offspring vary. (pacospace.com)
- This research puts to rest the idea that father contribution to sex ratio variation should be disregarded in vertebrates, and will stimulate research on evolutionary constraints to sex ratios-for example, whether fathers and mothers have divergent, coinciding, or neutral sex allocation interests. (pacospace.com)
- F isher (1930) presented a qualitative argument for the maintenance of an equal sex ratio, which predicts selection on any heritable variant that increases the production of the rarer sex. (genetics.org)
- The Boomsma-Grafen model predicts that sex ratios will be split when the following three conditions hold: (i) relatedness varies among colonies, (ii) workers control investment, and (iii) workers can determine whether they are in a high or low relatedness colony. (royalsocietypublishing.org)
- These signatures likely result from the biased transmission of the driver and selection on the suppressor for the maintenance of equal sex ratios. (genetics.org)
- Suppressors have been identified in a wide variety of meiotic drive systems and are predicted to be strongly favored by natural selection for the maintenance of equal sex ratios (reviewed by J aenike 2001 ). (genetics.org)
- Furthermore, the evolution of linked enhancer genes may enable drivers to evade suppression, setting off another bout of Fisherian selection for equal sex ratios ( H artl 1975 ). (genetics.org)
- 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. (biomedcentral.com)
- The study was located in the Comilla district from the eastern region which had adverse sex ratio at birth and the Rangpur district from the western region having normal sex ratio. (www.gov.uk)
- However, among mothers with no prior abortion, second-generation mothers had a normal sex ratio, while first-generation mothers gave birth to 142 boys for every 100 girls (95% CI 125 to 162 boys for every 100 girls). (ices.on.ca)
- According to the 2017 data bank from United Nations Population Division shows the sex ratio of male births per female births is 1.073. (chinesefortunecalendar.com)
- We downloaded the US natality data from 2007 to 2017, and then calculated the sex ratio at birth. (chinesefortunecalendar.com)
- The sex ratio at birth of USA was 1.0479 in 2017. (chinesefortunecalendar.com)
- In the aggregated results of 56 Demographic and Health Surveys in African countries, the ratio is 1.03, albeit with considerable country-to-country variation. (wikipedia.org)
- According to the study, "The genetic sex-determination system explains 24% of interspecific variation in ASRs in amphibians and 36% in reptiles. (mercola.com)
- Here, we characterize naturally occurring genetic variation at the Winters sex-ratio driver ( Distorter on the X or Dox ), its progenitor gene ( Mother of Dox or MDox ), and its suppressor gene ( Not Much Yang or Nmy ), which have been previously mapped and characterized. (genetics.org)
- This variation is mainly driven by sex differences in the survival of juveniles. (uni-bielefeld.de)
- We don't know what causes one sex to survive better than the other during the juvenile stage, but understanding this intriguing variation will be the next step of our research," he added. (uni-bielefeld.de)
- Allen GA, Antos JA (1993) Sex ratio variation in the dioecious shrub Oemleria cerasiformis . (springer.com)
- Reproductive specialization results from the instability of the evolutionarily stable strategy (ESS) sex ratio, and is independent of variation in relatedness. (royalsocietypublishing.org)
- Boomsma & Grafen ( 1990 , 1991 ) explained this phenomenon as a consequence of how selection on sex ratio is altered by the variation in relatedness among colonies. (royalsocietypublishing.org)
- CRAIG T.P., PRICE P.W. & ITAMI J.K. 1992: Facultative sex ratio shifts by a herbivorous insect in response to variation in host plant quality. (eje.cz)
- We further show the role played by the sperm nucleus area as a mediator in the relationship between individual genetic variation and sex-ratio bias. (pacospace.com)
- In the simplest case, a single queen that mates once, workers are predicted to bias investment in a ratio of 3 : 1 in favour of their sisters, with whom they share higher relatedness. (royalsocietypublishing.org)
- Ectoparasites are prominent examples of this bias, given that their sex ratios vary from strongly female- to strongly male-biased both among hosts and at the metapopulation level. (biomedcentral.com)
- Here we used Peromyscus leucopus to demonstrate that sex ratio is explained by an exclusive effect of the father, and suggest a likely mechanism by which male-driven sex-ratio bias is attained. (pacospace.com)
- Measures to reduce sex selection must include strict enforcement of existing legislation, the ensuring of equal rights for women, and public awareness campaigns about the dangers of gender imbalance. (pnas.org)
- Especially California, where the sex ratio imbalance during the Gold Rush period was quite notable. (marginalrevolution.com)
- And as we all know, California today is marked by women getting married and being stay at home mothers in notably higher proportion than other parts of the U.S., such as Utah, where the sex ratio imbalance was not so extreme, right? (marginalrevolution.com)
- Fascinating anecdotes that having nothing to do with the California Gold Rush and its notable sex ratio imbalance. (marginalrevolution.com)
- Though it is possible that you feel prostitution is a fine way to exploit supply and demand in a situation of an extreme sex ratio imbalance, of course. (marginalrevolution.com)
- The sex ratio imbalance during the California Gold Rush was very brief. (marginalrevolution.com)
- For instance, high sex ratios at birth in some Asian countries are now attributed to sex-selective abortion and infanticide due to a strong preference for sons. (nationmaster.com)
- Saadat and colleagues 1 reported a significantly high sex ratio (proportion male) in births to people exposed to oil and natural gas from an Iranian oilfield. (bmj.com)
- In accordance with our hypothesis and results of previous retrospective cohort studies on human subjects, mice with toxoplasmosis produced a higher sex ratio than controls, in the early phase of latent infection. (cambridge.org)
- April, May, June and July have higher sex ratios. (chinesefortunecalendar.com)
- In modern language, the 1:1 ratio is the evolutionarily stable strategy (ESS). (wikipedia.org)
- Spending equal amounts of resources to produce offspring of either sex is an evolutionarily stable strategy: if the general population deviates from this equilibrium by favoring one sex, one can obtain higher reproductive success with less effort by producing more of the other. (wikipedia.org)
- Essentially he argues that the 1:1 ratio is the evolutionarily stable strategy. (wikipedia.org)
- Obviously, a complete sweep of a sex-linked driver dooms a male-less (or female-less) population to extinction ( H amilton 1967 ), and natural selection strongly favors genetic factors that suppress drive and restore Mendelian segregation. (genetics.org)
- HAMILTON W.D. 1967: Extraordinary sex ratios. (eje.cz)
- But that ratio can be changed by environmental factors like temperature or even by seasonal shifts, said Kristen Navara, a reproductive endocrinologist with the UGA College of Agricultural and Environmental Sciences. (uga.edu)
- quaternary sex ratio - ratio in post-reproductive organisms Measuring these requires sophisticated mathematics since they lack clear boundaries. (wikipedia.org)
- 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. (scielo.br)
- Balshine-Earn S (1996) Reproductive Rates, Operational Sex Ratios, and Mate choice in St. Peter's Fish. (concordia.ca)
- Aaron S, Passera L, Keller L (1999) Evolution of social parasitism in ants: size of sexuals, sex ratio and mechanisms of caste determination. (springer.com)
- benefit-risk ratio a determination of the potential of a research study for positive effects on patients compared to the risks of doing harm. (thefreedictionary.com)
- Second, even if sex-ratio values in India are still beneath those of China, its potential contribution to the overall "masculinization" of Asia (and, consequently, of the world's population) is particularly formidable in view of India's demographic weight.1 The prospect of further worsening of India's sex composition requires close monitoring of current sex-ratio trends in the country. (unfpa.org)
- In 2000 the country's sex ratio at birth, an important demographic indicator, was at normal levels and was estimated to be fairly close to normal (105 boys to 100 girls). (unfpa.org)
- The current growth of 1 point per year since 2006 means that the ratio might cross the 115 mark within three years, which would significantly affect the country's demographic and sex structure. (unfpa.org)
- What her first-ever global analysis on birth sex ratio shows is that people living in areas with longer, darker winters - such as in temperate and subarctic climates - have more baby boys, accounting for 51.3 percent of births. (uga.edu)
- US National Center for Biotechnology Information published a study of The Association between Season of Pregnancy and Birth-Sex among Chinese in 2014. (chinesefortunecalendar.com)
- We demonstrate that the consequences of uneven sex ratios on cultural attitudes, labor supply decisions, and occupational choices can persist in the long run, well after sex ratios are back to the natural rate. (marginalrevolution.com)
- Our results underscore the importance of nonsexual interference competition that may often underlie the fitness consequences of skewed sex ratios. (ncbs.res.in)
- As of 2014, the global sex ratio at birth is estimated at 107 boys to 100 girls (1000 boys per 934 girls). (wikipedia.org)
- Due to higher female fetal mortality, the sex ratio at birth worldwide is commonly thought to be 107 boys to 100 girls, although this value is subject to debate in the scientific community. (wikipedia.org)
- If mortality is higher when caring than competing this diminishes the likelihood of sex role divergence because this strongly limits the mating success of the earlier deserting sex. (nih.gov)
- This son preference is manifest in sex-selective abortion and in discrimination in care practices for girls, both of which lead to higher female mortality. (pnas.org)
- Since that time, improved health care and conditions for women have resulted in reductions in female mortality, but these advances have now been offset by a huge increase in the use of sex-selective abortion, which became available in the mid-1980s. (pnas.org)
- It has been proposed that these environmental factors also explain sex differences in mortality. (wikipedia.org)
- We investigated whether hatching and fledging sex ratio and sex-specific chick mortality correlated with the ecological environment (laying date, clutch size, hatching order and year quality) and parental traits (condition, arrival date, experience and breeding success), over seven consecutive years. (wiley.com)
- Population-wide sex ratios and sex-specific mortality did not differ from parity, but clutch size, mass of the father, maternal breeding experience and to some extent year quality correlated with hatching sex ratio. (wiley.com)
- No clear patterns of sex-specific mortality were found, neither global nor related to parental traits. (wiley.com)
- I eliminated all Asian and African countries during a second round of analyses to get rid of any confound associated with sex-specific abortion," she said. (uga.edu)
- Because most analyses of sex ratio focus on sexual interactions, the relative importance of sexual versus nonsexual mechanisms remains unclear. (ncbs.res.in)
- This study analyses secular trends in gender ratios for live births over the second half of the 20th century. (bmj.com)
- Previous analyses indicated a 1:4 female-biased sex ratio at the foraging grounds, and based on our results, this largely reflects the use of unshaded beach hatcheries at some of the source rookeries for decades, which resulted in mostly female hatchlings. (edu.au)
- These results provide the first insights into the effect of daily thermocycles on sex differentiation in fish, and underline the key role of natural environmental cycles on the control of sex ratios during larval development, which may be applied to the manipulation of sex ratio in aquaculture. (stir.ac.uk)
- The project, Hormonal Manipulation of Offspring Sex Ratio in White Leghorn Chickens, lead by Dr. Kristen Navara is part of the Association's comprehensive research program encompassing all phases of poultry and egg production and processing. (poultryworld.net)
- For example, the male to female ratio falls from 1.05 for the group aged 15 to 65 to 0.70 for the group over 65 in Germany, from 1.00 to 0.72 in the United States, from 1.06 to 0.91 in mainland China, and from 1.07 to 1.02 in India. (wikipedia.org)
- First, rising sex ratios in India have been recorded since the early 1980s, and have since continued increasing with no sign, so far, of reversing course. (unfpa.org)
- According to United Nations Statistics Division, the sex ratio at China is 1.15 , India is 1.107, Armenia 1.129, Azerbaijan 1.125 and Vietnam is 1.097. (chinesefortunecalendar.com)
- My guess would be that the sex ratio at birth in India would definitely improve over the next four years, and while the PCPNDT activists may want to take credit for this, my guess is that it will movies like this which would have a far greater impact, and the tragedy is we'll never be able to give them the credit they deserve. (drmalpani.com)
- How to Use 2019 Chinese Baby Calendar for Chinese Baby Gender Prediction Chart based on Sex Ratio at birth statistic data in China, USA, India, Canada and Singapore. (chinesefortunecalendar.com)
- Without understanding the seasonal sex ratio birth data from China, USA, India, Singapore and Germany, you don't know how to use the Chinese Baby Gender Prediction Chart. (chinesefortunecalendar.com)
- The ratio at China is 1.15 , India is 1.107, Armenia 1.129, Azerbaijan 1.125 and Vietnam is 1.097. (chinesefortunecalendar.com)
- Here we studied the sex ratio of experimentally infected laboratory mice, expressed here as the proportion of males in the litter. (cambridge.org)
- The proportion of daughters increased with clutch size and maternal breeding experience, suggesting a decline in breeding performance or a resources balance solved by producing more of the cheaper sex. (wiley.com)
- No correlations of sex ratio with elevation as a proxy of environmental harshness and proportion of non-flowering individuals were found. (springer.com)
- Parental investment, sexual selection and sex ratios. (nih.gov)
- 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. (nih.gov)
- No effect of parental quality or extra-pair paternity on brood sex ratio in the blue tit (Parus caeruleus). (lancs.ac.uk)
- In addition, we found no significant effect on brood sex ratio of the individual quality of either parent as indicated by their biometrics, feather mite loads, time of breeding, or parental survival. (lancs.ac.uk)
- For instance, in crocodiles the sex of hatchlings is determined by temperature during incubation of the eggs. (mercola.com)
- We discuss the implications of hatchery practices that influence sex ratios of hatchlings and recommend future research to improve the management of marine turtles in the region. (edu.au)
- Even in the absence of sex selection practices, a range of "normal" sex ratios at birth of between 103 and 108 boys per 100 girls has been observed in different economically developed countries, and among different ethnic and racial groups within a given country. (wikipedia.org)
- We discuss the possible causes of the maintenance of presence-absence polymorphism in the Winters sex-ratio genes. (genetics.org)
- He added: "Surprisingly, some of our results in birds have striking parallels in human societies - for example, the frequency of divorce is related to sex ratio in some human societies in the same way. (bath.ac.uk)
- In human societies, however, sex ratios at birth may be considerably skewed by factors such as the age of mother at birth, and by sex-selective abortion and infanticide. (wikipedia.org)