When the relative fitness of sons and daughters differs, sex-allocation theory predicts that it would be adaptive for individuals to adjust their investment in different sexes of offspring. Sex ratio adjustment by females in response to the sexual attract. ...
Modification of offspring sex ratios in response to parental quality is predicted when the long-term fitness returns of sons and daughters differ. One factor that may influence a mothers sex allocation decision is the quality (or attractiveness) of her mate. We investigated whether the sex ratios of offspring produced by female Drosophila melanogaster are biased with respect to the age of the males to which they are mated, and whether there is an adaptive basis for this phenomenon. We found that females mated to old males (13 d post-eclosion) initially produced a greater proportion of daughters than did females mated to young males (1 d post-eclosion). This pattern does not appear to be due to a systematic difference in the numbers or mortality of the X- and Y-bearing sperm originating from old and young fathers, as the overall sex ratios of all offspring produced from a single copulation did not differ between broods fathered by the two types of males. The sons of older males fared worse in ...
Many countries with deficits in their female population see banning sex-selective abortion as a way to curb the observed sex imbalance without discussing potentially negative unintended consequences of this ban on female survival rates as parents may be forced to substitute post-natal for pre-natal sex-selection. This paper presents novel empirical evidence on the impact of access to abortion on sex ratios at birth and relative female infant mortality. We use the universe of birth and death registry data from Taiwan and exploit plausibly exogenous variation in the availability of sex-selective abortion caused by the legalization of abortions to identify the causal effects of sex-selective abortion on sex ratios at birth and excess female mortality. We find that sex-selective abortion increased the fraction of males at birth by approximately 0.7 percentage-points, accounting for approximately 100% of the observed increase in sex ratios at birth during the 1980s; and it decreased relative female ...
In utero, the male fetus is more prone to morbidity and mortality from external influences than the female fetus. Moreover, the male fetus is at greater risk of all obstetric complications than the female fetus and readers are referred to the review by Kraemer.21 Despite these adverse factors, males are invariably born in excess of females,2 implying an even higher conception rate of males over females than evinced by the sex ratio at birth.. In the first half of the 20th century, antenatal care improved dramatically in industrialised countries, which led to a fall in stillbirths, most of which would have otherwise been male. This therefore led to an increase in the M/F ratio.9,22. M/F then declined in several countries in the second half of the 20th century, and one study has proposed that M/F could be used as a sentinel health indicator.23 This is supported by data from Italy that showed that in metropolitan areas, M/F declined in comparison with the rest of the country where M/F ...
Can sex ratios at birth be used in the assessment of public health, and in the identification of causes of selected pathologies ...
While the effect of Operational Sex Ratio (OSR) on reproductive behaviour of males has been studied extensively, little is known of the response of females facing a female-biased OSR. We investigated the effect of different OSRs on female reproductive behaviour using the rosy bitterling, Rhodeus ocellatus, a freshwater fish that lays its eggs inside the gills of living freshwater mussels. Three levels of OSR (male/female ratio 1:1, 1:3 and 1:5) were tested. We demonstrated that inspection of the mussel (spawning substrate) by individual females increased with increasingly female-biased OSR, but that the rate of following territorial male decreased. Aggression towards other females was not affected by the OSR. Interestingly, when a male bitterling led a non-dominant female towards the mussel, the dominant female would become aggressive to the male and chase the non-dominant female away. Aggression towards male followed a bell-shaped pattern and was highest at an OSR of 1:3. In both the female-biased OSRs
Sex ratios in social insects have been the subject of intense study since Trivers & Hare (1976) first modified Fishers (1930) sex ratio theory to include kin selection, particularly in species with haplodiploid sex determination. Their argument made specific quantitative predictions about the investment sex ratio and predicted that it would be affected by several aspects of colony structure (mating frequency, worker reproduction, queen number, etc.). 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. Female-biased sex ratios have subsequently been confirmed in many social Hymenoptera (e.g. Queller & Strassmann 1998; Ratnieks et al. 2006).. When colonies are founded by multiple queens, by a multiply mated queen or when workers reproduce, the predictions about sex ratio also change. Many studies have explored the effect of mating frequency (e.g. Starr 1979; Nonacs ...
The study was carried out to record adverse pregnancy outcomes and to obtain information about sex ratio at birth in rural especially tribal areas in the State of Maharashtra, India. Although the tribal population is considered vulnerable to innumerable adversities, regretfully information about pregnancy wastage among them is not available. About 10% population of the state is tribal. The study of sex ratio at birth was planned as the overall sex ratio and child sex ratio had declined in the state. The cohort of antenatal cases registered in rural areas of Maharashtra in the calendar year 2008 was followed up to study the pregnancy outcomes. A retrospective study was carried out from October 2009 to August 2010. The outcomes of all the registered antenatal cases were recorded by the Auxiliary Nurse Midwives. The summary sheets were obtained by Block Medical Officers. The data was entered at the block level by trained data entry operators in specially designed web-based software. Adverse pregnancy
Sex of the fetus is genetically determined such that an equal number of sons and daughters are born in large populations. However, the ratio of female to male births across human populations varies signi fi cantly. Many factors have been impli- cated in this. The theory that natural selection should favour female o ff spring under suboptimal environmental conditions implies that pathogens may a ff ect secondary sex ratio (ratio of male to female births). Using regression models containing 13 potential confounding factors, we have found that variation of the secondary sex ratio can be predicted by seropreva- lence of Toxoplasma across 94 populations distributed across African, American, Asian and European continents. Toxoplasma seroprevalence was the third strongest predictor of secondary sex ratio, β = − 0·097, P < 0·01, after son pref- erence, β = 0·261, P < 0·05, and fertility, β = − 0·145, P < 0·001. Our preliminary results suggest that Toxoplasma gondii in- fection could be one ...
ABSTRACTRecent declines in the secondary sex ratio (SSR), defined as the ratio of males to females at birth, in some industrialized countries may be attributed to exposure to environmental toxicants such as persistent organic pollutants (POPs). This study aimed to evaluate the association of couples
The group sizes and sex ratios of vampire bat maternity and bachelor roosts are consistent with previous reports in Argentina [6,25,28,29]. Sex ratios were consistently male-biased no matter whether juvenile or adults were sampled at nets, or juveniles were caught inside maternity roosts (table 1).. There is only mixed evidence for a biased sex ratio at birth in other datasets. During a study in Costa Rica, Wilkinson ([15,16,18]; GS Wilkinson 1985, unpublished data) did not detect a male bias in the sex ratios of every newborn bat he captured from roosts at La Pacifica (18 females and 15 males) or in the sample of infant or juveniles from roosts in Palo Verde (19 females and 23 males). On the other hand, all detected pregnancies in a captive population [49] led to the births of four females and 16 males (binomial test, p = 0.012). A second captive breeding colony in Panama produced five females and nine males (nine females versus 25 males: binomial test, p = 0.009).. The male bias we observed in ...
We investigated the possible effects of ACP1 on the relationship between maternal smoking and sex ratio of offspring. ACP1 is a highly polymorphic enzyme involved in signal transduction of growth factors, glucose metabolism, flavoenzyme activity, and T-cell activation. A sample of 357 consecutive newborns from the population of Rome and a sample of 362 consecutive newborns from the population of Penne were studied. In both populations, among female newborns from smoking mothers there was a higher proportion of the A phenotype (associated with the lowest enzymatic activity) and a lower proportion of carriers of the *C allele (associated with the highest enzymatic activity) compared to female infants from nonsmoking mothers. In newborns from smoking mothers there was a positive correlation between sex ratio and ACP1 activity. The data suggest intrauterine selection induced by smoke that is dependent on sex and the ACP1 genotype of the zygote. It has been shown that low ACP1 activity is associated ...
The present study was conducted to evaluate the effect of fish oil supplementation prior to mating on secondary sex ratio of pups (the proportion of males at birth) in bitches. influenced by treatment and breed. Secondary sex ratio was higher in the treatment (105/164; 64.00%) than in the control (68/147; 46.30%) group (< 0.05; adjusted odds ratio = 2.068). Moreover secondary sex ratio was higher in Husky bitches (88/141; 62.40%) compared to German Shepherd (85/170; 50.00%; < 0.05; adjusted odds ratio = 1.661). In conclusion the present study showed that inclusion of fish oil in the diet of bitches prior to mating could increase the proportion of male pups at birth. In addition it appears that there might be variance among doggie breeds with regard to the sex ratio of offspring. studies has revealed sexual dimorphism of embryos in response to glucose during the early stages of embryo-genesis.7 8 The presence of glucose in the culture medium detrimentally impacts the development of female embryos ...
Define primary sex character. primary sex character synonyms, primary sex character pronunciation, primary sex character translation, English dictionary definition of primary sex character. Noun 1. primary sex character - the genetically determined sex characteristics bound up with reproduction primary sex characteristic, primary sexual...
Vivekananda et al(1)report that when controlled for sex, cases of sporadic amyotrophic lateral sclerosis (ALS) have a lower mean finger length ratio R [where R = (2D / 4D) and 2D and 4D are the lengths of the 2nd and 4th digits respectively] than healthy controls. These authors interpret their finding as indicating prenatal involvement of high concentrations of intrauterine testosterone, T. However, their interpretation is not the only one : another possibility arises from the reported variation of R with adult sex hormone levels(2). So (some cases of) ALS may arise either as a consequence of high maternal T levels, or of high levels of the patients own postnatal T (or both). Here I offer a means of discriminating between these two hypotheses. I have adduced substantial quantities of data to support the hypothesis that mammalian (including human) offspring sex ratios at birth are partially controlled by parental hormone levels around the time of conception(3-5). Ex hypothesi, high levels of T ...
... However because chalk and limestone are porous this terrain dries out far quicker than it would on more.
Women who want to increase their chances of giving birth to a girl should live closer to the equator, says a University of Georgia researcher, whose recent study sheds light on how temperature and day length can influence human reproduction. Most animal sex ratios are 50:50. 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. Her recent research with certain hamsters and mice shows that more males are born in winter when days are shorter, and that more females are born if day length is longer. Sparked by curiosity and these findings, she wanted to see if the same held true for humans.. She dug through the CIAs The World Factbook and other government publications to gather data on every nation with a decade of uninterrupted statistics. She gathered statistics on 202 nations. Navara then analyzed the figures based on latitude, average ...
Theory predicts that males adapt to sperm competition by increasing their investment in testis mass to transfer larger ejaculates. Experimental and comparative data support this prediction. Nevertheless, the relative importance of sperm competition in testis size evolution remains elusive, because experiments vary only sperm competition whereas comparative approaches confound it with other variables, in particular male mating rate. We addressed the relative importance of sperm competition and male mating rate by taking an experimental evolution approach. We subjected populations of Drosophila melanogaster to sex ratios of 1:1, 4:1, and 10:1 (female:male). Female bias decreased sperm competition but increased male mating rate and sperm depletion. After 28 generations of evolution, males from the 10:1 treatment had larger testes than males from other treatments. Thus, testis size evolved in response to mating rate and sperm depletion, not sperm competition. Furthermore, our experiment demonstrated ...
The population sex ratio of the majority of sexually reproducing organisms is close to 1 1 selection will normally promote the production of the rarer sex, so
Sex-selective abortion is the practice of terminating a pregnancy based upon the predicted sex of the infant. The selective abortion of female fetuses is most common in areas where cultural norms value male children over female children, especially in parts of East Asia and South Asia (particularly in countries such as Peoples Republic of China, India and Pakistan), as well as in the Caucasus, and Western Balkans. Sex-selective abortion affects the human sex ratio-the relative number of males to females in a given age group, with China and India, the two most populous countries of the world, having unbalanced gender ratios. Studies and reports focusing on sex-selective abortion are predominantly statistical; they assume that birth sex ratio-the overall ratio of boys and girls at birth for a regional population, is an indicator of sex-selective abortion. This assumption has been questioned by some scholars. Scholars who support the assumption, suggest that the expected birth sex ratio range is ...
For the 63rd year in a row, the number of boys born in the United States outnumbers births of girls - in 2002 94,232 more boys than girls were born. This is the central finding of a new Centers for Disease Control and Prevention (CDC) report that examines total sex ratios at birth for over six decades. The total sex ratio is the number of male births divided by female births times 1,000. ...
Sex Ratio is the ratio of no. of males to females in a population. Sex ratio is used to describe the number of females per 1000 of males. As per provisional census data of 2011, the national average sex ratio shows an increase from 933 in 2001 to 940 in 2011. The population ratio in India 2011 is 940 females per 1000 of males.. The following statewise sex ratio list of india is as per provisional census data of 2011 :. ...
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Define Gibbs Josiah Willard. Gibbs Josiah Willard synonyms, Gibbs Josiah Willard pronunciation, Gibbs Josiah Willard translation, English dictionary definition of Gibbs Josiah Willard. Josiah Willard 1839-1903. American mathematician and physicist who formulated the theoretical foundation of physical chemistry, developed vector analysis,...
Abortion in India is legal only up to twenty weeks of pregnancy under specific conditions and situations, which are broadly defined as: the continuance of the pregnancy would involve a risk to the life of the pregnant woman or of grave injury of physical or mental health, or there is a substantial risk that if the child were born, it would suffer from such physical or mental abnormalities as to be seriously handicapped. Recently, the Supreme Court permitted a rape survivor to terminate her pregnancy at 24 weeks, which is beyond the permissible 20 weeks limit prescribed under the Medical Termination of Pregnancy Act, 1971. An adult woman requires no other persons consent except her own. In many parts of India, daughters are not preferred and hence sex-selective abortion is commonly practised, resulting in an unnatural male to female population sex ratio due to millions of developing girls selectively being targeted for termination before birth. Gender hierarchies, cultural norms, values and ...
Definition of primary sex c's in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is primary sex c's? Meaning of primary sex c's as a legal term. What does primary sex c's mean in law?
If you thought Punjab and Haryana were the only concern areas in terms of low sex ratio, many other states too are showing long-term ominous trends. Bihar -the only major state apart from Jammu and Kashmir and Gujarat that saw sex ratio decline from 2001 to 2011 -has silently slipped from a leading position on the key gender indicator to a worrisome situation. If Bihar sticks to its trend and Punjab to its present performance, the two could be competing in 2021. Haryana-another historical culprit -maintained abysmal sex ratios in the mid-800s till 2011, when it has made a small improvement of 16 points to a still abysmal 877 ...
One of the major changes that have taken place in India over the last two decades is a significant shift in the sex ratio at birth, as techniques for prenatal sex determination have become more widely available. There has, however, been little analysis of which factors influence the decision to abort female fetuses at the individual level. Furthermore, the sparse literature does not address the relationship between fertility, spacing and the demand for sex selective abortions, which may lead to biased estimates. Using data from the three rounds of the National Family and Health Survey this paper relies on the observed spacing between births to examine the determinants of the demand for sex selective abortions. By employing a discrete hazard model it is possible to simultaneously control for the fertility and abortion decisions, while taking account of censoring and unobservable characteristics that might affect either.. ...
Objective: although numerous studies have reported the association between birth season and sex ratio, few studies have been conducted in subtropical regions in a non-Western setting. The present study assessed the effects of pregnancy season on birth sex ratio in China. Methods: We conducted a national population-based retrospective study from 2006-2008 with 3175 children-parents pairs enrolled in the Northeast regions of China. Demographics and data relating to pregnancy and birth were collected and analyzed. A multiple logistical regression model was fitted to estimate the regression coefficient and 95% confidence interval (CI) of refractive error for mother pregnancy season, adjusting for potential confounders. Results: After adjusting for parental age (cut-off point was 30 years), region, nationality, mother education level, and mother miscarriage history, there is a significant statistical different mother pregnancy season on birth-sex. Compared with mothers who were pregnant in spring, those
Downloadable! The missing women phenomenon in many Asian countries has previously been regarded as the result of son preference. However, some studies have argued half of the missing women can be explained by infection with Hepatitis B virus (HBV). We demonstrate that the probability of having a male birth is only slightly higher for HBV mothers than for mothers without HBV. The sex ratio at birth rises for the higher birth order and that in families where the first two children are female. Our findings suggest that HBV status has little impact on the missing women phenomenon. (JEL I12, J16)
some does not influence sex. Instead two X chromosomes signal the fl...A chromosome is a single DNA molecule that may contain different units...Even though it is the presence or absence of the human Y chromosome th...Early in his career Erickson was part of the research team that ident... This signaling process is not unique to embryonic sex differentiation...,Fruit,fly,gene,research,may,shed,light,on,human,disease,processes,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
When it comes to producing billionaires, America is doing great. Until 2005, multimillionaires could still make the Forbes list of the 400 richest Americans. In 2006, the Forbes 400 went billionaires only. This year, youd need a Forbes 482 to fit all the billionaires. A billion dollars is a lot of dough. Queen Elizabeth II, British monarch for five decades, would have to add $400 million to her $600 million fortune to reach $1 billion. And shed need another $300 million to reach the Forbes 400 minimum of $1.3 billion. The average Forbes 400 member has $3.8 billion.
Power Surge: The Billionaire Club, Volume 1 (MFM) by Dixie Lynn Dwyer (Power Surge: The Billionaire Club). In Their Greatest Treasure, Nash and Riker blame themselves for their lovers death. Theyre billionaires, and their clu...
Results The mortality rate for the cohort was 67.9 per 1000 live births (B=74.4; G=62.4). This declined significantly as wealth index improved (from 102.4 to 25.4 per 1000 live births). The HR for girls declined from 1.57 (95% CI 1.0 to 2.5) in the wealthiest to 0.67 (0.3 to 1.4) in the lowest tertile. There was no change in total or sex specific mortality rates according to caste or fathers education. Mothers education beyond 10th grade resulted in sharp decline in mortality (14 per 1000 live births) but did not impact the sex differential in mortality. The sex ratio at birth was worst for population with highest wealth index and highest level of maternal educational attainment. ...
Background The study was carried out to record adverse pregnancy outcomes and to obtain information about sex ratio at birth in rural especially tribal areas in the State of Maharashtra, India....
Abstract: Motivation: Reproducibility analyses of biologically relevant microarray studies have mostly focused on overlap of detected biomarkers or correlation of differential expression evidences across studies. For clinical utility, direct inter-study prediction (i.e. to establish a prediction model in one study and apply to another) for disease diagnosis or prognosis prediction is more important. Normalization plays a key role for such a task. Traditionally, sample-wise normalization has been a standard for inter-array and inter-study normalization. For gene-wise normalization, it has been implemented for intra-study or inter-study predictions in a few papers while its rationale, strategy and effect remain unexplored.. Results: In this article, we investigate the effect of gene-wise normalization in microarray inter-study prediction. Gene-specific intensity discrepancies across studies are commonly found even after proper sample-wise normalization. We explore the rationale and necessity of ...
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India will have approximately 6.8 million missing female births between 2017 and 2030 because of sex-selective abortions, according to a recently published study.
Author(s): Leticia Aviles Subject(s): CX.34, CX.35 Category: Brief Article Abstract:. Understanding the evolutionary transitions from lower to higher levels of organization (e. g., from genes to chromosomes, prokaryotic cells to eukaryotic cells, single-celled organisms to multicellular organisms, multicellular organisms to social groups) requires addressing at least two questions: What caused the lower level units to become associated into a higher level entity? Under what circumstances does the primary focus of selection shift from the lower level units to the higher level entities? Using insights gained through the study of the cooperative spiders, I explore these questions as they pertain primarily to the association of individuals into groups. I first consider the possibility that intercolony selection may be an effective evolutionary force in the cooperative spiders. I do so by discussing the evolution of their highly female-biased sex ratios within the context of a multilevel selection ...
We are interested in how demography, environmental factors, and evolutionary selective pressures influence reproductive morphology, genitalic function, mating behaviors, and holistic mating systems, especially in the leiobunine opilionids - a.k.a. harvesters, harvestpeople or "daddy-longlegs.". We combine macroevolutionary and population-level approaches to understanding the biodiversity of arthropods, incorporating next-generation genomic sequencing, functional morphology, bioinformatics, and cytological methods into our toolkit. Current projects are focused on species groups in the United States and Japan with intriguing reproductive traits: parthenogenesis, sex ratio bias, reproductive armaments, and potential reproductive endosymbionts.. ...
Blueheads," as Thalassoma bifasciatum can commonly be referred, are protogynus sequential hermaphrodites that form large, male dominated harems in which a group of females establish a female-only hierarchy. The male controls the group, provides protection and manufactures sperm; the largest female in the group is the primary egg producer and to a certain extent controls the lesser females. Because blueheads live in groups with highly biased sex ratios - many females, one male - eggs are "a dime a dozen" - theyre cheap. If the lead reproductive female should die or be killed, the next largest female in the hierarchy will hurriedly succeed her and take over as primary ova supplier with little fuss. Whereas there are an abundance of females and only a single male, the sperm he contributes is of greater importance to the group than are eggs. The eggs are expensive, sperm are cheap rule - although still valid in regards to resource allotment for an individual - in this social scenario no longer ...
Nairobi, Kenya , AFP , The family of Tanzanias only billionaire Mohammed Dewji, who was kidnapped last week in Dar es Salaam, on Monday announced a reward of nearly half a million dollars for information on his whereabouts.. Gunmen snatched Dewji, 43, listed by Forbes as Africas youngest billionaire, as he entered a hotel gym in Tanzanias economic capital last Thursday morning.. "The family is offering a reward of a billion shillings ($437,000/376,000 euros) to any person who has information leading to the whereabouts of our son," family spokesman Azim Dewji told a press conference.. Interior Minister Kangi Lugola said Saturday that security forces were "working day and night" to find Dewji, with 20 people arrested so far.. Officials have implicated foreigners in the abduction, saying he was taken by "whites". ...
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