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OUP accepted manuscript. J Mammal 2022. [DOI: 10.1093/jmammal/gyac041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Long Y, Chen Q, Larsson H, Rzhetsky A. Observable variations in human sex ratio at birth. PLoS Comput Biol 2021; 17:e1009586. [PMID: 34855745 PMCID: PMC8638995 DOI: 10.1371/journal.pcbi.1009586] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 10/25/2021] [Indexed: 11/18/2022] Open
Abstract
The human sex ratio at birth (SRB), defined as the ratio between the number of newborn boys to the total number of newborns, is typically slightly greater than 1/2 (more boys than girls) and tends to vary across different geographical regions and time periods. In this large-scale study, we sought to validate previously-reported associations and test new hypotheses using statistical analysis of two very large datasets incorporating electronic medical records (EMRs). One of the datasets represents over half (∼ 150 million) of the US population for over 8 years (IBM Watson Health MarketScan insurance claims) while another covers the entire Swedish population (∼ 9 million) for over 30 years (the Swedish National Patient Register). After testing more than 100 hypotheses, we showed that neither dataset supported models in which the SRB changed seasonally or in response to variations in ambient temperature. However, increased levels of a diverse array of air and water pollutants, were associated with lower SRBs, including increased levels of industrial and agricultural activity, which served as proxies for water pollution. Moreover, some exogenous factors generally considered to be environmental toxins turned out to induce higher SRBs. Finally, we identified new factors with signals for either higher or lower SRBs. In all cases, the effect sizes were modest but highly statistically significant owing to the large sizes of the two datasets. We suggest that while it was unlikely that the associations have arisen from sex-specific selection mechanisms, they are still useful for the purpose of public health surveillance if they can be corroborated by empirical evidences. The human sex ratio at birth (SRB), usually slightly greater than 1/2, have been reported to vary in response to a wide array of exogenous factors. In the literature, many such factors have been posited to be associated with higher or lower SRBs, but the studies conducted so far have focused on no more than a few factors at a time and used far smaller datasets, thus prone to generating spurious correlations. We performed a series of statistical tests on 2 large, country-wide health datasets representing the United States and Sweden to investigate associations between putative exogenous factors and the SRB, and were able to validate a set of previously-reported associations while also discovering new signals. We propose to interpret these results simply as public health indicators awaiting further empirical confirmation rather than as implicated in (adaptive) sexual selection mechanisms.
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Affiliation(s)
- Yanan Long
- Department of Chemistry, The University of Chicago, Chicago, Illinois, United States of America
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
- Institute of Genomics and Systems Biology, The University of Chicago, Chicago, Illinois, United States of America
| | - Qi Chen
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Henrik Larsson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
- School of Medical Sciences, Örebro University, Örebro, Sweden
| | - Andrey Rzhetsky
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
- Institute of Genomics and Systems Biology, The University of Chicago, Chicago, Illinois, United States of America
- Department of Human Genetics and Committee on Quantitative Methods in Social, Behavioral, and Health Sciences, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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Lockley EC, Eizaguirre C. Effects of global warming on species with temperature-dependent sex determination: Bridging the gap between empirical research and management. Evol Appl 2021; 14:2361-2377. [PMID: 34745331 PMCID: PMC8549623 DOI: 10.1111/eva.13226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/05/2021] [Accepted: 03/11/2021] [Indexed: 12/31/2022] Open
Abstract
Global warming could threaten over 400 species with temperature-dependent sex determination (TSD) worldwide, including all species of sea turtle. During embryonic development, rising temperatures might lead to the overproduction of one sex and, in turn, could bias populations' sex ratios to an extent that threatens their persistence. If climate change predictions are correct, and biased sex ratios reduce population viability, species with TSD may go rapidly extinct unless adaptive mechanisms, whether behavioural, physiological or molecular, exist to buffer these temperature-driven effects. Here, we summarize the discovery of the TSD phenomenon and its still elusive evolutionary significance. We then review the molecular pathways underpinning TSD in model species, along with the hormonal mechanisms that interact with temperatures to determine an individual's sex. To illustrate evolutionary mechanisms that can affect sex determination, we focus on sea turtle biology, discussing both the adaptive potential of this threatened TSD taxon, and the risks associated with conservation mismanagement.
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Affiliation(s)
- Emma C. Lockley
- School of Biological and Chemical SciencesQueen Mary University LondonLondonUK
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Wu R, Wu X, Li S, Li G, Jiang Z, Zhong H, Wang B, Yang S, Wei W. Predator odor exposure increases social contact in adolescents and parental behavior in adulthood in Brandt's voles. Behav Processes 2021; 186:104372. [PMID: 33667486 DOI: 10.1016/j.beproc.2021.104372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 11/28/2022]
Abstract
Research suggests that predation risk during adolescence can program adult stress response and emotional behavior; however, little is known about the short-term and lasting residual effects of this experience on social behavior. We explored this concept in social Brandt's voles (Lasiopodomys brandtii). Adolescent male and female voles were exposed to distilled water, rabbit urine (as a non-predator stimulus), and cat urine for 60 min daily from postnatal day (PND) 28-49. Social play tests were conducted immediately following exposure on PND 28, 35, 42, and 49. In the social play test, repeated cat odor (CO) exposure enhanced the contact behavior of voles with their cagemate. Adolescent exposure to CO did not affect behavioral responses toward unrelated pups in the alloparental behavior test or same-sex individuals in the social interaction test. However, exposure to CO significantly enhanced the licking/grooming behavior of voles towards their own pups in the home cage parental behavior test. Repeated CO exposure significantly inhibited weight gain in male voles during adolescence. This effect was transmitted to the next generation, with lower weight gain in offspring before weaning. Following repeated CO exposure, males tended to have more female offspring whereas females produced more offspring, suggesting an adaptive strategy to increase inclusive fitness under predatory risk. These findings demonstrate that adolescent exposure to predatory risk augments adolescent social contact and adult parental behavior and suggest a role for improved inclusive fitness in mediating long-term outcomes.
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Affiliation(s)
- Ruiyong Wu
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China.
| | - Xueyan Wu
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Shan Li
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Guran Li
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Ziyi Jiang
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Haocheng Zhong
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Bo Wang
- Genetic Engineering Laboratory, School of Biological and Environmental Engineering, Xi'an University of Arts and Science, Xi'an, Shaanxi 710065, China
| | - Shengmei Yang
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Wanhong Wei
- Department of Animal Behavior, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, Jiangsu 225009, China.
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Hair cortisol levels in pregnancy as a possible determinant of fetal sex: a longitudinal study. J Dev Orig Health Dis 2021; 12:902-907. [PMID: 33407972 DOI: 10.1017/s2040174420001300] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Stress during pregnancy has been widely studied and associated to different variables, usually with negative results for the health of the mother and the newborn, such as having a higher risk of suffering postpartum depression, premature birth, obstetrics complications or low birthweight, among others. However, there are not many lines of research that study the role that the sex of the baby plays on this specific stress and vice versa. Thus, the main objective was to analyse the relationship between the sex of the offspring and the stress of the mothers in the first trimester of pregnancy. In order to achieve this, 108 women had their biological stress measured (trough hair cortisol levels) and psychological stress evaluated (the Prenatal Distress Questionnaire (PSS), the Perceived Stress Scale (PDQ) and the Stress Vulnerability Inventory (IVE)). The results revealed significant differences in maternal hair cortisol levels in the first trimester based on the sex of the baby they had given birth to (t = -2.04; P < 0.05): the concentration of the hormone was higher if the baby was a girl (164.36:54.45-284.87 pg/mg) than if it was a boy (101.13:37.95-193.56 pg/mg). These findings show that the sex of the future baby could be conditioned, among many other variables, by the mother´s stress levels during conception and first weeks of pregnancy. Further research is needed in this area to support our findings.
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Abdel Hamid ER, Sharaf NE, Ahmed HH, Ahmed A, Mossa ATH. In utero exposure to organochlorine pesticide residues and their potential impact on birth outcomes and fetal gender. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:33703-33711. [PMID: 32533481 DOI: 10.1007/s11356-020-09411-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 05/21/2020] [Indexed: 06/11/2023]
Abstract
Being the largest agriculture country in the Arab world, Egypt was one of the major consumer of organochlorine pesticides (OCPs) in this area, continued to have a heavy burden of OCPs in the environment. There is growing concern that OCPs could pass from the maternal circulation through the placenta to the fetal circulation and pose several health risks to their fetuses. The current study was intended to identify OCPs residue exposure in healthy pregnant women and to justify the potential impacts of these residues on their fetuses. In this study, the prevalence of 18 OCPs was estimated in 81 maternal and cord blood samples, using Agilent 7890, gas chromatograph equipped with micro-electron capture detector (GC-μECD). Our data signposted that the heptachlor epoxide has the highest detection rate among all residues in both maternal (32%) and cord blood serum (27.16%). DDTs were still quantifiable, but with the lowest quantifiable percentage. More than 85% of mothers' serum with detectable residues transfer OCPs residue to their fetuses in a statistically significant manner (x = 42.9, p value < 0.001). The present findings showed no significant growth retardation, or preterm delivery induced by in utero exposure to the most abundant residues. There is growing evidence that exposure to OCPs residue has profound impact on sex ratio. Methoxychlor, in this study be deemed as testosterone triggers which yields high boys ratio (x = 4.37, p < 0.05). In conclusion, Egypt continued to have a heavy burden of OCPs residues, and fetuses and infants are especially the most vulnerable groups to their adverse health effects. Exposure to OCPs may disrupt the maternal hormones, which regulate the offspring gender, but these results need to be validated in larger sample sizes.
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Affiliation(s)
| | - Nevin E Sharaf
- Department of Environmental and Occupational Medicine, National Research Centre, Giza, Egypt
| | - Hanaa H Ahmed
- Hormones Department, National Research Centre, Giza, Egypt
| | | | - Abdel-Tawab H Mossa
- Pesticide Chemistry Department, Chemical Industries Research Division, National Research Centre (NRC), 33 El Bohouth Street (former El Tahrir St.), Giza, P.O. 12622,, Egypt.
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Liczbińska G, Králík M. Body size at birth in babies born during World War II: The evidence from Poland. Am J Hum Biol 2020; 32:e23421. [PMID: 32293764 DOI: 10.1002/ajhb.23421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/27/2020] [Accepted: 03/30/2020] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES The objective of the study was to determine whether exposure of pregnant women to stresses caused by World War II (WWII) negatively affected pregnancy and perinatal outcomes. METHODS Individual medical documents deposited in the Gynaecology and Obstetrics Clinic of Medical University, Poznań (1934-1943; N = 7058) were evaluated. These were divided into two birth cohorts: before WWII and during it. Frequency tables were constructed for the numbers of pregnancy outcomes: miscarriages, stillbirths, live births, and neonatal deaths, according to the period of birth and sex of a child. The numbers of recorded days were standardized and the numbers of cases per day were computed. Statistical differences in the averages (medians) between periods and years under study were tested. Birth weight, length, and body mass index (BMI) were compared according to the periods related to WWII. RESULTS Significant differences in proportions of males, females, and subjects with unknown sex were found between the periods: a higher proportion of males and different structure of/within negative outcomes were found during WWII. Children born during WWII were heavier and longer than those born before it. CONCLUSIONS As an explanation, adverse conditions of WWII, related to the psychological stress and food shortages, could have influenced greater elimination of fetuses and neonates of male sex during pregnancy and shortly after delivery. Higher average body size in newborns recorded during WWI could be explained by a hidden process of increased early prenatal mortality of weaker individuals, differences in average gestation length between the periods, differences in parity, or some undocumented differences in social/ethnic composition of the sample.
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Affiliation(s)
- Grażyna Liczbińska
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.,Laboratory of Morphology and Forensic Anthropology (LaMorFA), Department of Anthropology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Miroslav Králík
- Laboratory of Morphology and Forensic Anthropology (LaMorFA), Department of Anthropology, Faculty of Science, Masaryk University, Brno, Czech Republic
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Effects of predator-induced stress during pregnancy on reproductive output and offspring quality in Brandt’s voles (Lasiopodomys brandtii). EUR J WILDLIFE RES 2020. [DOI: 10.1007/s10344-019-1354-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Walsh K, McCormack CA, Webster R, Pinto A, Lee S, Feng T, Krakovsky HS, O'Grady SM, Tycko B, Champagne FA, Werner EA, Liu G, Monk C. Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes. Proc Natl Acad Sci U S A 2019; 116:23996-24005. [PMID: 31611411 PMCID: PMC6883837 DOI: 10.1073/pnas.1905890116] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maternal prenatal stress influences offspring neurodevelopment and birth outcomes including the ratio of males to females born; however, there is limited understanding of what types of stress matter, and for whom. Using a data-driven approach with 27 variables from questionnaires, ambulatory diaries, and physical assessments collected early in the singleton pregnancies of 187 women, 3 latent profiles of maternal prenatal stress emerged that were differentially associated with sex at birth, birth outcomes, and fetal neurodevelopment. Most women (66.8%) were in the healthy group (HG); 17.1% were in the psychologically stressed group (PSYG), evidencing clinically meaningful elevations in perceived stress, depression, and anxiety; and 16% were in the physically stressed group (PHSG) with relatively higher ambulatory blood pressure and increased caloric intake. The population normative male:female secondary sex ratio (105:100) was lower in the PSYG (2:3) and PHSG (4:9), and higher in the HG (23:18), consistent with research showing diminished male births in maternal stress contexts. PHSG versus HG infants were born 1.5 wk earlier (P < 0.05) with 22% compared to 5% born preterm. PHSG versus HG fetuses had decreased fetal heart rate-movement coupling (P < 0.05), which may indicate slower central nervous system development, and PSYG versus PHSG fetuses had more birth complications, consistent with previous findings among offspring of women with psychiatric illness. Social support most strongly differentiated the HG, PSYG, and PHSG groups, and higher social support was associated with increased odds of male versus female births. Stress phenotypes in pregnant women are associated with male vulnerability and poor fetal outcomes.
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Affiliation(s)
- Kate Walsh
- Ferkauf Graduate School of Psychology, Yeshiva University, The Bronx, NY 10461
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032
| | - Clare A McCormack
- Center for Science and Society, Columbia University, New York, NY 10027
| | - Rachel Webster
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032
| | - Anita Pinto
- Data Science, Columbia University, New York, NY 10027
| | - Seonjoo Lee
- Division of Behavioral Medicine, New York State Psychiatric Institute, New York, NY 10032
- Department of Biostatistics (in Psychiatry), Mailman School of Public Health, Columbia University, New York, NY 10032
| | - Tianshu Feng
- Department of Biostatistics (in Psychiatry), Mailman School of Public Health, Columbia University, New York, NY 10032
| | - H Sloan Krakovsky
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032
| | - Sinclaire M O'Grady
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032
| | - Benjamin Tycko
- Hackensack-Meridian Health Center for Discovery and Innovation, Nutley, NJ 07110
| | - Frances A Champagne
- Department of Psychiatry, Columbia University, New York, NY 10032
- Department of Psychology, University of Texas at Austin, Austin, TX 78712
| | - Elizabeth A Werner
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032
- Department of Psychiatry, Columbia University, New York, NY 10032
| | - Grace Liu
- Department of Psychiatry, Columbia University, New York, NY 10032
| | - Catherine Monk
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032;
- Division of Behavioral Medicine, New York State Psychiatric Institute, New York, NY 10032
- Department of Psychiatry, Columbia University, New York, NY 10032
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Fishman R, Vortman Y, Shanas U, Koren L. Non-model species deliver a non-model result: Nutria female fetuses neighboring males in utero have lower testosterone. Horm Behav 2019; 111:105-109. [PMID: 30790563 DOI: 10.1016/j.yhbeh.2019.02.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/06/2019] [Accepted: 02/14/2019] [Indexed: 12/15/2022]
Abstract
Neighboring fetuses may impact their siblings in various respects, depending on their in utero location and sex. The effects of the intrauterine position (IUP) are widely studied in model organisms, especially laboratory bred murine strains that are characterized by short gestations and altricial offspring. In some species, the proximity to a male fetus and its higher circulating testosterone masculinizes neighboring female fetuses. In utero testosterone exposure might be manifested as higher testosterone concentrations, which contribute to a variation in morphology, reproductive potential and behavior. In this study, we examined the influence of neighboring an opposite sex fetus on testosterone levels in a feral animal model characterized by a long gestation and precocious offspring. Using necropsies of culled nutria (Myocastor coypus), we accurately determined the IUP and quantified testosterone immunoreactivity in fetal hair. We found that as expected, both male and female fetuses neighboring a male in utero had longer anogenital distance. However, females adjacent to males in utero showed lower testosterone levels than male fetuses, while testosterone levels of females without a male neighbor did not differ from those of males. This surprising result suggests an alternative mode by which local exogenous steroids may modify the local fetal environment. Our study emphasizes the importance of examining known phenomena in species with different life histories, other than the traditional murine models, to enhance our understanding of the evolutionary mechanisms that are driving sexual differentiation.
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Affiliation(s)
- Ruth Fishman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yoni Vortman
- Hula Research Center, Department of Animal Sciences, Tel-Hai College, Upper Galilee 1220800, Israel
| | - Uri Shanas
- Faculty of Life Sciences, University of Haifa-Oranim, Tivon 3600600, Israel
| | - Lee Koren
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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Edwards AM, Cameron EZ, Deakin JE, Ezaz T, Pereira JC, Ferguson‐Smith MA, Robert KA. Sexual conflict in action: An antagonistic relationship between maternal and paternal sex allocation in the tammar wallaby, Notamacropus eugenii. Ecol Evol 2019; 9:4340-4348. [PMID: 31031909 PMCID: PMC6476839 DOI: 10.1002/ece3.4813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 11/22/2018] [Indexed: 01/29/2023] Open
Abstract
Sex ratio biases are often inconsistent, both among and within species and populations. While some of these inconsistencies may be due to experimental design, much of the variation remains inexplicable. Recent research suggests that an exclusive focus on mothers may account for some of the inconsistency, with an increasing number of studies showing variation in sperm sex ratios and seminal fluids. Using fluorescent in-situ hybridization, we show a significant population-level Y-chromosome bias in the spermatozoa of wild tammar wallabies, but with significant intraindividual variation between males. We also show a population-level birth sex ratio trend in the same direction toward male offspring, but a weaning sex ratio that is significantly female-biased, indicating that males are disproportionately lost during lactation. We hypothesize that sexual conflict between parents may cause mothers to adjust offspring sex ratios after birth, through abandonment of male pouch young and reactivation of diapaused embryos. Further research is required in a captive, controlled setting to understand what is driving and mechanistically controlling sperm sex ratio and offspring sex ratio biases and to understand the sexually antagonistic relationship between mothers and fathers over offspring sex. These results extend beyond sex allocation, as they question studies of population processes that assume equal input of sex chromosomes from fathers, and will also assist with future reproduction studies for management and conservation of marsupials.
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Affiliation(s)
- Amy M. Edwards
- Department of Ecology, Environment and Evolution, School of Life SciencesLa Trobe UniversityMelbourneVictoriaAustralia
| | - Elissa Z. Cameron
- School of Biological SciencesUniversity of CanterburyChristchurchNew Zealand
| | - Janine E. Deakin
- Institute for Applied EcologyUniversity of CanberraCanberraAustralian Capital TerritoryAustralia
| | - Tariq Ezaz
- Institute for Applied EcologyUniversity of CanberraCanberraAustralian Capital TerritoryAustralia
| | - Jorge C. Pereira
- Department of Veterinary MedicineUniversity of CambridgeCambridgeUK
- Cytocell Ltd.CambridgeUK
| | | | - Kylie A. Robert
- Department of Ecology, Environment and Evolution, School of Life SciencesLa Trobe UniversityMelbourneVictoriaAustralia
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Fishman R, Vortman Y, Shanas U, Koren L. Cortisol advantage of neighbouring the opposite sex in utero. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171636. [PMID: 30839724 PMCID: PMC6170571 DOI: 10.1098/rsos.171636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 08/09/2018] [Indexed: 05/14/2023]
Abstract
Population sex ratios naturally fluctuate around equality. It is argued that the production of an equal number of male and female offspring by individual parents should be favoured by selection, if all costs and benefits are equal. Theoretically, an even sex ratio should yield the highest probability for a fetus to be adjacent to a fetus of the opposite sex in utero. This may cause developmental costs or benefits that have been overlooked. We examined the physiological and developmental parameters associated with in utero sex ratios in the nutria (Myocastor coypus), an invasive wildlife species with a strong reproductive output. Using hair testing, we found that litters with even sex ratios had the highest average cortisol levels. Fetuses neighbouring the opposite sex exhibited longer trunks than those neighbouring the same sex, which might imply better lung development. Our results are the first, to our knowledge, to link intra-utero sex ratios and fetal cortisol and suggest that fetal cortisol might be a mechanism by which even sex ratios are maintained via developmental advantages.
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Affiliation(s)
- R. Fishman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Y. Vortman
- Hula Research Center, Department of Animal Sciences, Tel-Hai College, Upper Galilee 1220800, Israel
| | - U. Shanas
- Faculty of Life Sciences, University of Haifa—Oranim, Tivon 3600600, Israel
| | - L. Koren
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
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Female-biased sex ratios are associated with higher maternal testosterone levels in nutria (Myocastor coypus). Behav Ecol Sociobiol 2018. [DOI: 10.1007/s00265-018-2517-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Seyfang J, Kirkwood RN, Tilbrook AJ, Ralph CR. The sex ratio of a gilt’s birth litter can affect her fitness as a breeding female. ANIMAL PRODUCTION SCIENCE 2018. [DOI: 10.1071/an17192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Lifetime reproductive performance and behaviour are established in utero driven by genetics and the steroidal milieu of the uterine environment. Developing males synthesise androgens that can be absorbed by females in the litter. Consequently, the proportion of males in a litter has the potential to affect both lifetime reproductive performance and behaviour of female littermates. Although reproductive potential is understandably important for gilt selection, behaviour is becoming progressively more important as group housing of sows increases. Aggression can be a cause for removal from the breeding herd, and can also negatively affect reproductive performance and herd longevity. This review covers existing evidence of masculinisation in rodents and sheep, the mechanism causing masculinisation, and the knowledge gaps surrounding masculinisation in pigs. Premature culling of gilts is an economic and animal welfare issue in the pork industry resulting in low retention of gilts and reduced productivity. The selection of gilts needs to be improved to incorporate both lifetime reproductive potential and behaviour. We determined that there is cause to investigate the effect of the birth litter sex ratio of a gilt on her suitability for selection into the breeding herd.
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Panahi S, Fahami F, Deemeh MR, Tavalaee M, Gourabi H, Nasr-Esfahani MH. Chances to Have A Boy after Gender Selection by Pre-Implantation Genetic Screening Are Reduced in Couples with only Girls and without A Boy Sired by The Male Partner. INTERNATIONAL JOURNAL OF FERTILITY & STERILITY 2017; 10:350-356. [PMID: 28042415 PMCID: PMC5134750 DOI: 10.22074/ijfs.2016.4828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 06/25/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND Gender selection and family planning have their roots in human history. Despite great interest in these fields, very few scientific propositions exist which could explain why some family do not attain the desired sex. Therefore, the aim of this study was to evaluate whether sex of previous child or children could affect the outcomes of pre-implantation genetic screening (PGS). MATERIALS AND METHODS This historical cohort study including 218 PGS cases referring to Isfahan Fertility and Infertility Center (IFIC). Couples were grouped as those who their male child passed away or her husbands' has a son(s) from their previous marriage (n=70) and couples who just have daughter (n=148). Male normal blastocysts were transferred for both groups. The outcomes of PGS including pregnancy, implantation and abortion rates, along with possible confounding factors were compared between the two groups. RESULTS Significant differences in pregnancy, implantation and abortion rates were observed between couples whose their male partner had/has one boy (n=70) compared to those who have just girl(s) (n=148) despite similar number and quality of male normal blastocyst transferred in the two groups. Confounding factors were also considered. CONCLUSION The Ybearing spermatozoa in male partners with no history of previous boy have lower ability to support a normal development to term, compared to male partners with previous history of boy requesting family balancing.
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Affiliation(s)
- Soryya Panahi
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran; Department of Midwifery, School of Nursing and Midwifery Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Fariba Fahami
- Department of Midwifery, School of Nursing and Midwifery Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Reza Deemeh
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Marziyeh Tavalaee
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Hamid Gourabi
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Mohammad Hossain Nasr-Esfahani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran; Isfahan Fertility and Infertility Center, Isfahan, Iran
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17
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Borowik T, Jędrzejewska B. Heavier females produce more sons in a low‐density population of red deer. J Zool (1987) 2016. [DOI: 10.1111/jzo.12430] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- T. Borowik
- Mammal Research Institute Polish Academy of Sciences Białowieża Poland
| | - B. Jędrzejewska
- Mammal Research Institute Polish Academy of Sciences Białowieża Poland
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18
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Cameron EZ, Edwards AM, Parsley LM. Developmental sexual dimorphism and the evolution of mechanisms for adjustment of sex ratios in mammals. Ann N Y Acad Sci 2016; 1389:147-163. [PMID: 27862006 DOI: 10.1111/nyas.13288] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 09/28/2016] [Accepted: 10/05/2016] [Indexed: 12/15/2022]
Abstract
Sex allocation theory predicts biased offspring sex ratios in relation to local conditions if they would maximize parental lifetime reproductive return. In mammals, the extent of the birth sex bias is often unpredictable and inconsistent, leading some to question its evolutionary significance. For facultative adjustment of sex ratios to occur, males and females would need to be detectably different from an early developmental stage, but classic sexual dimorphism arises from hormonal influences after gonadal development. Recent advances in our understanding of early, pregonadal sexual dimorphism, however, indicate high levels of dimorphism in gene expression, caused by chromosomal rather than hormonal differences. Here, we discuss how such dimorphism would interact with and link previously hypothesized mechanisms for sex-ratio adjustment. These differences between males and females are sufficient for offspring sex both to be detectable to parents and to provide selectable cues for biasing sex ratios from the earliest stages. We suggest ways in which future research could use the advances in our understanding of sexually dimorphic developmental physiology to test the evolutionary significance of sex allocation in mammals. Such an approach would advance our understanding of sex allocation and could be applied to other taxa.
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Affiliation(s)
- Elissa Z Cameron
- School of Biological Sciences, University of Tasmania, Hobart, Australia.,School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Amy M Edwards
- School of Biological Sciences, University of Tasmania, Hobart, Australia
| | - Laura M Parsley
- School of Biological Sciences, University of Tasmania, Hobart, Australia
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19
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Correa LA, León C, Ramírez-Estrada J, Soto-Gamboa M, Sepúlveda RD, Ebensperger LA. Masculinized females produce heavier offspring in a group living rodent. J Anim Ecol 2016; 85:1552-1562. [DOI: 10.1111/1365-2656.12588] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 08/10/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Loreto A. Correa
- Departamento de Ecología; Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Cecilia León
- Departamento de Ecología; Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Juan Ramírez-Estrada
- Departamento de Ecología; Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Mauricio Soto-Gamboa
- Facultad de Ciencias; Instituto de Ciencias Ambientales y Evolutivas; Universidad Austral de Chile; Casilla 567 Valdivia Chile
| | - Roger D. Sepúlveda
- Facultad de Ciencias; Instituto de Ciencias Ambientales y Evolutivas; Universidad Austral de Chile; Casilla 567 Valdivia Chile
| | - Luis A. Ebensperger
- Departamento de Ecología; Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
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Edwards AM, Cameron EZ, Pereira JC, Wapstra E, Ferguson-Smith MA, Horton SR, Thomasson K. Gestational experience alters sex allocation in the subsequent generation. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160210. [PMID: 27493776 PMCID: PMC4968468 DOI: 10.1098/rsos.160210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
Empirical tests of adaptive maternal sex allocation hypotheses have presented inconsistent results in mammals. The possibility that mothers are constrained in their ability to adjust sex ratios could explain some of the remaining variation. Maternal effects, the influence of the maternal phenotype or genotype on her developing offspring, may constrain sex allocation through physiological changes in response to the gestational environment. We tested if maternal effects constrain future parental sex allocation through a lowered gestational stress environment in laboratory mice. Females that experienced lowered stress as embryos in utero gave birth to female-biased litters as adults, with no change to litter size. Changes in offspring sex ratio was linked to peri-conceptual glucose, as those females that had increasing blood glucose peri-conceptionally gave birth to litters with a higher male to female sex ratio. There was, however, no effect of the lowered prenatal stress for developing male embryos and their sperm sex ratio when adult. We discuss the implications of maternal effects and maternal stress environment on the lifelong physiology of the offspring, particularly as a constraint on later maternal sex allocation.
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Affiliation(s)
- A. M. Edwards
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - E. Z. Cameron
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - J. C. Pereira
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
- Cytocell Ltd., Cambridge Technopark, Newmarket Road, Cambridge, UK
| | - E. Wapstra
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | | | - S. R. Horton
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - K. Thomasson
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
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21
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Are there physiological constraints on maternal ability to adjust sex ratios in mammals? J Zool (1987) 2016. [DOI: 10.1111/jzo.12327] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Kim TB, Oh JK, Kim KT, Yoon SJ, Kim SW. Does the Mother or Father Determine the Offspring Sex Ratio? Investigating the Relationship between Maternal Digit Ratio and Offspring Sex Ratio. PLoS One 2015; 10:e0143054. [PMID: 26575995 PMCID: PMC4648576 DOI: 10.1371/journal.pone.0143054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 10/30/2015] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE In mammals, high parental testosterone levels present around the time of conception are thought to skew offspring sex ratio toward sons. The second to fourth digit ratio (digit ratio) is now widely accepted as a negative correlate of prenatal testosterone. Thus, we investigated the association between digit ratio and offspring sex ratio. METHODS A total of 508 Korean patients (257 males and 251 females) less than 60 years old who had one or more offspring were prospectively enrolled. The lengths of the 2nd and 4th digits of the right hand were measured by a single investigator using a digital vernier calliper. Next, the patients' lifetime offspring birth sex ratios were investigated. RESULTS Maternal (rather than paternal) digit ratio was significantly associated with the number of sons (r = -0.153, p = 0.015), number of daughters (r = 0.130, p = 0.039), and offspring sex ratio (r = -0.171, p = 0.007). And, the maternal digit ratio was a significant factor for predicting offspring sex ratio (B = -1.620, p = 0.008) on multiple linear regression analysis. The female patients with a lower digit ratio (< 0.95) were found to have a higher offspring sex ratio (0.609 versus 0.521, p = 0.046) compared to those with a higher digit ratio (≥ 0.95). Furthermore, females in the low digit ratio group have a probability 1.138 greater of having sons than females in the high digit ratio group. CONCLUSIONS Maternal digit ratio was negatively associated with offspring sex ratio. Females with a lower digit ratio were more likely to have more male offspring compared to those with a higher digit ratio. Thus, our results suggest that the sex of offspring might be more influenced by maternal rather than paternal factors.
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Affiliation(s)
- Tae Beom Kim
- Department of Urology, Gachon University Gil Hospital, Incheon, Republic of Korea
| | - Jin Kyu Oh
- Department of Urology, Gachon University Gil Hospital, Incheon, Republic of Korea
| | - Kwang Taek Kim
- Department of Urology, Gachon University Gil Hospital, Incheon, Republic of Korea
| | - Sang Jin Yoon
- Department of Urology, Gachon University Gil Hospital, Incheon, Republic of Korea
| | - Soo Woong Kim
- Department of Urology, Seoul National University Hospital, Seoul, Republic of Korea
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Moore EPB, Hayward M, Robert KA. High density, maternal condition, and stress are associated with male-biased sex allocation in a marsupial. J Mammal 2015. [DOI: 10.1093/jmammal/gyv129] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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24
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Setchell JM, Smith TE, Knapp LA. Androgens in a female primate: Relationships with reproductive status, age, dominance rank, fetal sex and secondary sexual color. Physiol Behav 2015; 147:245-54. [DOI: 10.1016/j.physbeh.2015.04.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 11/25/2022]
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25
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Kolk M, Schnettler S. Socioeconomic status and sex ratios at birth in Sweden: No evidence for a Trivers-Willard effect for a wide range of status indicators. Am J Hum Biol 2015; 28:67-73. [DOI: 10.1002/ajhb.22756] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 05/13/2015] [Accepted: 05/25/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Martin Kolk
- Demography Unit; Department of Sociology; Stockholm University; Stockholm SE-106 91 Sweden
| | - Sebastian Schnettler
- Department of Sociology; Faculty of History and Sociology, University of Konstanz; D-78457 Konstanz Germany
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26
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Boulton RA, Fletcher AW. Do mothers prefer helpers or smaller litters? Birth sex ratio and litter size adjustment in cotton-top tamarins (Saguinus oedipus). Ecol Evol 2015; 5:598-606. [PMID: 25691984 PMCID: PMC4328765 DOI: 10.1002/ece3.1396] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 12/15/2014] [Indexed: 11/21/2022] Open
Abstract
Sex allocation theory has been a remarkably productive field in behavioral ecology with empirical evidence regularly supporting quantitative theoretical predictions. Across mammals in general and primates in particular, however, support for the various hypotheses has been more equivocal. Population-level sex ratio biases have often been interpreted as supportive, but evidence for small-scale facultative adjustment has rarely been found. The helper repayment (HR) also named the local resource enhancement (LRE) hypothesis predicts that, in cooperatively breeding species, mothers invest more in the sex which assists with rearing future offspring and that this bias will be more pronounced in mothers who require extra assistance (i.e., due to inexperience or a lack of available alloparents). We tested these hypotheses in captive cotton-top tamarins (Saguinus oedipus) utilizing the international studbook and birth records obtained through a questionnaire from ISIS-registered institutions. Infant sex, litter size, mother's age, parity, and group composition (presence of nonreproductive subordinate males and females) were determined from these records. The HR hypothesis was supported over the entire population, which was significantly biased toward males (the "helpful" sex). We found little support for helper repayment at the individual level, as primiparous females and those in groups without alloparents did not exhibit more extreme tendencies to produce male infants. Primiparous females were, however, more likely to produce singleton litters. Singleton births were more likely to be male, which suggests that there may be an interaction between litter size adjustment and sex allocation. This may be interpreted as supportive of the HR hypothesis, but alternative explanations at both the proximate and ultimate levels are possible. These possibilities warrant further consideration when attempting to understand the ambiguous results of primate sex ratio studies so far.
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Affiliation(s)
- Rebecca A Boulton
- Department of Biological Sciences, University of ChesterChester, U.K
- School of Biology, University of St AndrewsSt Andrews, U.K
| | - Alison W Fletcher
- Department of Biological Sciences, University of ChesterChester, U.K
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27
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Schnettler S, Klüsener S. Economic stress or random variation? Revisiting German reunification as a natural experiment to investigate the effect of economic contraction on sex ratios at birth. Environ Health 2014; 13:117. [PMID: 25533777 PMCID: PMC4391084 DOI: 10.1186/1476-069x-13-117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 12/04/2014] [Indexed: 06/04/2023]
Abstract
BACKGROUND The economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SRB) following economic decline. However, as many factors influence the SRB, this hypothesis is difficult to test empirically. Thus, researchers make use of quasi-experiments such as German reunification: The economy in East, but not in West Germany, underwent a rapid decline in 1991. A co-occurrence of a decline in the East German SRB in 1991 has been interpreted by some as support for the ESH. However, another explanation might be that the low SRB in 1991 stems from increased random variation in the East German SRB due to a drastically reduced number of births during the crisis. We look into this alternative random variation hypothesis (RVH) by re-examining the German case with more detailed data. METHODS Our analysis has two parts. First, using aggregate-level birth register data for all births in the period between 1946 and 2011, we plot the quantum and variance of the SRB and the number of births and unemployment rates, separately for East and West Germany, and conduct a time series analysis on the East German SRB over time. Second, we model the odds for a male birth at the individual level in a multiple logistic regression (1991-2010, ~13.9 million births). Explanatory variables are related to the level of the individual birth, the mother of the child born, and the regional economic context. RESULTS The aggregate-level analysis reveals a higher degree of variation of the SRB in East Germany. Deviations from the time trend occur in several years, seemingly unrelated to economic development, and the deviation in 1991 is not statistically significant. The individual-level analysis confirms that the 1991-drop in the East German SRB cannot directly be attributed to economic development and that there is no statistically significant effect of economic development on sex determination in East or West Germany. CONCLUSION Outcomes support the RVH but not the ESH. Furthermore, our results speak against a statistically significant effect of the reunification event itself on the East German SRB. We discuss the relative importance of behavioral and physiological responses to macro-level stressors, a distinction that may help integrate previously mixed findings.
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Affiliation(s)
- Sebastian Schnettler
- Department of Sociology, University of Konstanz, Box 40, Universitätsstr. 10, 78457, Konstanz, Germany.
| | - Sebastian Klüsener
- Max Planck Institute for Demographic Research, Konrad-Zuse-Str. 1, 18057, Rostock, Germany.
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Ryan CP, Anderson WG, Berkvens CN, Hare JF. Maternal gestational cortisol and testosterone are associated with trade-offs in offspring sex and number in a free-living rodent (Urocitellus richardsonii). PLoS One 2014; 9:e111052. [PMID: 25353347 PMCID: PMC4213000 DOI: 10.1371/journal.pone.0111052] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/26/2014] [Indexed: 11/30/2022] Open
Abstract
The adaptive manipulation of offspring sex and number has been of considerable interest to ecologists and evolutionary biologists. The physiological mechanisms that translate maternal condition and environmental cues into adaptive responses in offspring sex and number, however, remain obscure. In mammals, research into the mechanisms responsible for adaptive sex allocation has focused on two major endocrine axes: the hypothalamic pituitary adrenal (HPA) axis and glucocorticoids, and the hypothalamic pituitary gonadal (HPG) axis and sex steroids, particularly testosterone. While stress-induced activation of the HPA axis provides an intuitive model for sex ratio and litter size adjustment, plasma glucocorticoids exist in both bound and free fractions, and may be acting indirectly, for example by affecting plasma glucose levels. Furthermore, in female mammals, activation of the HPA axis stimulates the secretion of adrenal testosterone in addition to glucocorticoids (GCs). To begin to untangle these physiological mechanisms influencing offspring sex and number, we simultaneously examined fecal glucocorticoid metabolites, free and bound plasma cortisol, free testosterone, and plasma glucose concentration during both gestation and lactation in a free-living rodent (Urocitellus richardsonii). We also collected data on offspring sex and litter size from focal females and from a larger study population. Consistent with previous work in this population, we found evidence for a trade-off between offspring sex and number, as well as positive and negative correlations between glucocorticoids and sex ratio and litter size, respectively, during gestation (but not lactation). We also observed a negative relationship between testosterone and litter size during gestation (but not lactation), but no effect of glucose on either sex ratio or litter size. Our findings highlight the importance of binding proteins, cross-talk between endocrine systems, and temporal windows in the regulation of trade-offs in offspring sex and number.
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Affiliation(s)
- Calen P. Ryan
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
| | - W. Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - James F. Hare
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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Mack LA, Lay DC, Eicher SD, Johnson AK, Richert BT, Pajor EA. Growth and reproductive development of male piglets are more vulnerable to midgestation maternal stress than that of female piglets12. J Anim Sci 2014; 92:530-48. [PMID: 24398844 DOI: 10.2527/jas.2013-6773] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- L. A. Mack
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907
| | - D. C. Lay
- USDA-Agricultural Research Service, Livestock Behavior Research Unit, West Lafayette, IN 47907
| | - S. D. Eicher
- Department of Animal Science, Iowa State University, Ames, IA 50011
| | - A. K. Johnson
- Department of Animal Science, Iowa State University, Ames, IA 50011
| | - B. T. Richert
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907
| | - E. A. Pajor
- Department of Production Animal Health, University of Calgary, Calgary, AB, CA T2N IN4
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Szenczi P, Bánszegi O, Groó Z, Altbäcker V. Anogenital distance and condition as predictors of litter sex ratio in two mouse species: a study of the house mouse (Mus musculus) and mound-building mouse (Mus spicilegus). PLoS One 2013; 8:e74066. [PMID: 24069268 PMCID: PMC3777973 DOI: 10.1371/journal.pone.0074066] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/30/2013] [Indexed: 11/23/2022] Open
Abstract
The Trivers - Willard hypothesis (1973) suggests that the maternal condition may affect the female's litter size and sex ratio. Since then other factors had been found. Previous findings revealed in the case of some mammalian species, that females with larger anogenital distance have smaller litters, while the sex ratio is male-biased. That has only been demonstrated in laboratory animals, while the genetic diversity of a wild population could mask the phenomenon seen in laboratory colonies. We examined the connection between morphological traits (weight and anogenital distance) and the reproductive capacity of two wild mice species, the house mouse and the mound-building mice. We showed in both species that anogenital distance and body weight correlated positively in pre-pubertal females, but not in adults. Neither the house mouse nor the mound-building mouse mothers' weight had effect on their litter's size and sex ratio. Otherwise connection was found between the mothers' anogenital distance and their litters' sex ratio in both species. The results revealed that females with larger anogenital distance delivered male biased litter in both species. The bias occurred as while the number of female pups remained the same; mothers with large anogenital distance delivered more male pups compared to the mothers with small anogenital distance. We concluded that a female's prenatal life affects her reproductive success more than previously anticipated.
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Affiliation(s)
- Péter Szenczi
- Department of Ethology, Eötvös Loránd University, Göd, Hungary
| | - Oxána Bánszegi
- Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zita Groó
- Department of Ethology, Eötvös Loránd University, Göd, Hungary
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Abstract
The ability to adjust sex ratios at the individual level exists among all vertebrate groups studied to date. In many cases, there is evidence for facultative adjustment of sex ratios in response to environmental and/or social cues. Because environmental and social information must be first transduced into a physiological signal to influence sex ratios, hormones likely play a role in the adjustment of sex ratio in vertebrates, because the endocrine system acts as a prime communicator that directs physiological activities in response to changing external conditions. This symposium was developed to bring together investigators whose work on adjustment of sex ratio represents a variety of vertebrate groups in an effort to draw comparisons between species in which the sex-determination process is well-established and those in which more work is needed to understand how adjustments in sex ratio are occurring. This review summarizes potential hormone targets that may underlie the mechanisms of adjustment of sex ratio in humans, non-human mammals, birds, reptiles, and fishes.
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Affiliation(s)
- Kristen J Navara
- Department of Poultry Science, The University of Georgia, Athens, GA 30602, USA
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Thogerson CM, Brady CM, Howard RD, Mason GJ, Pajor EA, Vicino GA, Garner JP. Winning the genetic lottery: biasing birth sex ratio results in more grandchildren. PLoS One 2013; 8:e67867. [PMID: 23874458 PMCID: PMC3707872 DOI: 10.1371/journal.pone.0067867] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 05/21/2013] [Indexed: 11/18/2022] Open
Abstract
Population dynamics predicts that on average parents should invest equally in male and female offspring; similarly, the physiology of mammalian sex determination is supposedly stochastic, producing equal numbers of sons and daughters. However, a high quality parent can maximize fitness by biasing their birth sex ratio (SR) to the sex with the greatest potential to disproportionately outperform peers. All SR manipulation theories share a fundamental prediction: grandparents who bias birth SR should produce more grandoffspring via the favored sex. The celebrated examples of biased birth SRs in nature consistent with SR manipulation theories provide compelling circumstantial evidence. However, this prediction has never been directly tested in mammals, primarily because the complete three-generation pedigrees needed to test whether individual favored offspring produce more grandoffspring for the biasing grandparent are essentially impossible to obtain in nature. Three-generation pedigrees were constructed using 90 years of captive breeding records from 198 mammalian species. Male and female grandparents consistently biased their birth SR toward the sex that maximized second-generation success. The most strongly male-biased granddams and grandsires produced respectively 29% and 25% more grandoffspring than non-skewing conspecifics. The sons of the most male-biasing granddams were 2.7 times as fecund as those of granddams with a 50∶50 bias (similar results are seen in grandsires). Daughters of the strongest female-biasing granddams were 1.2 times as fecund as those of non-biasing females (this effect is not seen in grandsires). To our knowledge, these results are the first formal test of the hypothesis that birth SR manipulation is adaptive in mammals in terms of grandchildren produced, showing that SR manipulation can explain biased birth SR in general across mammalian species. These findings also have practical implications: parental control of birth SR has the potential to accelerate genetic loss and risk of extinction within captive populations of endangered species.
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Affiliation(s)
- Collette M. Thogerson
- Ecological Services, U.S. Fish & Wildlife Service, Arlington, Virginia, United States of America
| | - Colleen M. Brady
- Department of Animal Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Richard D. Howard
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Georgia J. Mason
- Department of Animal and Poultry Science, University of Guelph, Ontario, Canada
| | | | - Greg A. Vicino
- Collections Husbandry Science, San Diego Zoo Global, San Diego, California, United States of America
| | - Joseph P. Garner
- Department of Comparative Medicine, and by Courtesy, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
- * E-mail:
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Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio. Naturwissenschaften 2013; 100:559-69. [DOI: 10.1007/s00114-013-1052-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 04/18/2013] [Accepted: 04/19/2013] [Indexed: 11/30/2022]
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Schnettler S. Revisiting a sample of U.S. billionaires: how sample selection and timing of maternal condition influence findings on the Trivers-Willard effect. PLoS One 2013; 8:e57446. [PMID: 23437389 PMCID: PMC3578789 DOI: 10.1371/journal.pone.0057446] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Accepted: 01/23/2013] [Indexed: 11/18/2022] Open
Abstract
Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that lead parents with high levels of resources to bias offspring sex composition to favor sons and parents with low levels of resources to favor daughters. This hypothesis has been tested in samples of wealthy individuals but with mixed results. Here, I argue that both sample selection due to a high number of missing cases and a lacking specification of the timing of wealth accumulation contribute to this equivocal pattern. This study improves on both issues: First, analyses are based on a data set of U.S. billionaires with near-complete information on the sex of offspring. Second, subgroups of billionaires are distinguished according to the timing when they acquired their wealth. Informed by recent insights on the timing of a potential TW effect in animal studies, I state two hypotheses. First, billionaires have a higher share of male offspring than the general population. Second, this effect is larger for heirs and heiresses who are wealthy at the time of conception of all of their children than for self-made billionaires who acquired their wealth during their adult lives, that is, after some or all of their children have already been conceived. Results do not support the first hypothesis for all subgroups of billionaires. But for males, results are weakly consistent with the second hypothesis: Heirs but not self-made billionaires have a higher share of male offspring than the U.S. population. Heiresses, on the other hand, have a much lower share of male offspring than the U.S. average. This hints to a possible interplay of at least two mechanisms affecting sex composition. Implications for future research that would allow disentangling the distinct mechanisms are discussed.
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James WH. Hypotheses on the stability and variation of human sex ratios at birth. J Theor Biol 2012; 310:183-6. [DOI: 10.1016/j.jtbi.2012.06.038] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/13/2012] [Accepted: 06/28/2012] [Indexed: 11/26/2022]
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Parental status and gender preferences for children: is differential fertility stopping consistent with the trivers-willard hypothesis? J Biosoc Sci 2012; 45:683-704. [PMID: 22989525 DOI: 10.1017/s0021932012000557] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Based on evolutionary reasoning, Trivers & Willard (1973) predicted status-biased sex composition and parental investment with son-preferencing effects in higher, and daughter-preferencing effects in lower status groups. Previous research shows mixed results. This study uses event-history methods and Swedish register data to study one possible mechanism in isolation: do parents in different status groups vary in their proclivities to continue fertility based on the sex composition of previous offspring? The results show no support for the Trivers-Willard hypothesis on a wide range of different status indicators. Future research on the stated hypothesis should focus on physiological rather than behavioural mechanisms.
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James WH. The relevance of the epidemiology of human sex ratios at birth to some medical problems. Paediatr Perinat Epidemiol 2012; 26:181-9. [PMID: 22471677 DOI: 10.1111/j.1365-3016.2012.01267.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human sex ratio (proportion male at birth) shows considerable variation which is central to reproductive epidemiology. For example, it has reportedly shown significant secular trends and wartime variation, and it has shown replicated variation with parental exposure to several deleterious chemicals. However, scientific progress in identifying the causes of these forms of variation has been very slow and, as described here, this has elicited some scepticism. Benefits may be expected from identifying these causes. Two (non-competing) hypotheses have emerged, the first relating to the hormonal regulation of sex ratio at conception, and the second to the sex-selective effects of stressors during pregnancy. It is shown here that if the first of these hypotheses was substantially correct, it would illuminate a number of scientific and medical problems, for example, the causes of autism and of selected sex-related congenital malformations and obstetric pathologies.
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Affiliation(s)
- William H James
- Department of Genetics, Evolution and Environment, University College London, London, UK.
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Bánszegi O, Szenczi P, Dombay K, Bilkó A, Altbäcker V. Anogenital distance as a predictor of attractiveness, litter size and sex ratio of rabbit does. Physiol Behav 2012; 105:1226-30. [PMID: 22251966 DOI: 10.1016/j.physbeh.2012.01.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 12/26/2011] [Accepted: 01/04/2012] [Indexed: 11/17/2022]
Abstract
In the case of some mammalian species, females with larger anogenital distance (AGD) have smaller litters, where the sex ratio is male-biased. The first aim of the present study was to test whether this phenomenon exists in the Lagomorph group, especially in rabbits. The results revealed that does with large AGD have significantly smaller and lighter litters with a male biased sex ratio; with fewer females but not more males. The second aim of the present study was to test whether males differentiate between females differing in their AGD and are thus capable of choosing the more fertile and fecund does. Males showed a stronger response to the chin marks of females with small AGD than to the marks of females with large AGD. Our results suggest that variation in the prenatal hormonal environment, reflected through variation in AGD, could have long-term consequences on mate choice and population dynamics.
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Affiliation(s)
- Oxána Bánszegi
- Department of Ethology, Eötvös Loránd University, H-2131 Göd, Jávorka u. 14., Hungary.
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Rosenfeld CS. Periconceptional influences on offspring sex ratio and placental responses. Reprod Fertil Dev 2012; 24:45-58. [DOI: 10.1071/rd11906] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Maternal diet and secondary factors can strikingly influence fetal outcomes, including biasing offspring sex ratio and altering the molecular biological responses of the conceptus, namely within the placenta. Alterations in the in utero environment might also lead to profound developmental origin of health and disease (DOHaD) outcomes into adulthood, including increased risk for cardiovascular disease, obesity and cancer, with males in general being at greater risk for these diseases. Female mice maintained on a very high fat (VHF) diet birth more sons than those on a chow-based and low fat (LF), high carbohydrate diet, with the latter group producing more daughters. However, neither the underlying mechanisms that contribute to this shift in offspring sex ratio nor when they occur during pregnancy have been resolved. In this review, we consider the evidence that maternal diet and other factors influence secondary sex ratio in a variety of species, including humans, and discuss when this skewing might occur. Additionally, we examine how fetal sex and maternal diet influences gene expression patterns in the mouse placenta, which serves as the primary nutrient acquisition and communication organ between the mother and her developing pups. These adaptations to diet observed as changes in gene expression are likely to provide insight into how the placenta buffers the fetus proper from environmental shifts in nutrient availability during pregnancy and whether male and female conceptuses respond differently to such challenges.
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40
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Monclús R, Tiulim J, Blumstein DT. Older mothers follow conservative strategies under predator pressure: the adaptive role of maternal glucocorticoids in yellow-bellied marmots. Horm Behav 2011; 60:660-5. [PMID: 21930131 DOI: 10.1016/j.yhbeh.2011.08.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/31/2011] [Accepted: 08/31/2011] [Indexed: 11/29/2022]
Abstract
When the maternal environment is a good predictor of the offspring environment, maternal glucocorticoid (GC) levels might serve to pre-program offspring to express certain phenotypes or life-history characteristics that will increase their fitness. We conducted a field study to assess the effects of naturally occurring maternal GC levels on their offspring in yellow-bellied marmots (Marmota flaviventris) subjected to different predator pressures. Maternal fecal corticosteroid metabolites (FCM) were positively correlated with predator pressure. Predators had both direct and indirect effects on pups. We found that older mothers with higher FCM levels had smaller and female-biased litters. Moreover, sons from older mothers with high FCM levels dispersed significantly more than those from older mothers with low FCM levels, whereas the opposite pattern was found in pups from younger mothers. These age-related effects may permit females to make adaptive decisions that increase their pups' fitness according to their current situation.
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Affiliation(s)
- Raquel Monclús
- Department of Ecology and Evolutionary Biology, University of California, 621 Charles E Young Drive South, Los Angeles, CA 90095-1606, USA.
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41
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Ryan CP, Anderson WG, Gardiner LE, Hare JF. Stress-induced sex ratios in ground squirrels: support for a mechanistic hypothesis. Behav Ecol 2011. [DOI: 10.1093/beheco/arr169] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Grant VJ, Konečná M, Sonnweber RS, Irwin RJ, Wallner B. Macaque mothers’ preconception testosterone levels relate to dominance and to sex of offspring. Anim Behav 2011. [DOI: 10.1016/j.anbehav.2011.07.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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43
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Mixed sex allocation strategies in a polytocous mammal, the house mouse (Mus musculus). Behav Ecol Sociobiol 2011. [DOI: 10.1007/s00265-011-1229-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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44
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ROBERT KA, SCHWANZ LE. Emerging sex allocation research in mammals: marsupials and the pouch advantage. Mamm Rev 2010. [DOI: 10.1111/j.1365-2907.2010.00168.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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45
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Grant VJ, Chamley LW. Can mammalian mothers influence the sex of their offspring peri-conceptually? Reproduction 2010; 140:425-33. [PMID: 20591970 DOI: 10.1530/rep-10-0137] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Although controversial, growing evidence from evolutionary biology suggests that the mammalian mother may have a role in influencing the sex of her offspring. However, there is competing information on the molecular mechanisms by which such influence could be manifested. The new initiatives are based on hypotheses from evolutionary biology: the 'good condition' hypothesis, which suggests that post conception, higher levels of maternal glucose may differentially promote the development of male embryos; and the 'maternal dominance' hypothesis, which proposes that before conception, higher follicular testosterone may influence the development of the ovum so that it emerges already adapted to receive an X- or a Y-chromosome-bearing spermatozoon. Now, it seems these hypothesised mechanisms could be operating in synchrony, each complementing and reinforcing the other. On the other hand, there are continuing problems in identifying a precise sequence of mechanisms as evidenced from research in sperm-sorting. Research on high-fat diets and the sex ratio in polytocous species may indicate important differences in proximate mechanisms for sex allocation between polytocous and monotocous mammals.
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Affiliation(s)
- Valerie J Grant
- Department of Psychological Medicine Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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Navara KJ. Programming of offspring sex ratios by maternal stress in humans: assessment of physiological mechanisms using a comparative approach. J Comp Physiol B 2010; 180:785-96. [PMID: 20544204 DOI: 10.1007/s00360-010-0483-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 05/18/2010] [Accepted: 05/20/2010] [Indexed: 01/23/2023]
Abstract
Sex ratio adjustment has become a hot topic in ecology and evolutionary biology, as documentations of sex ratio skews are numerous, and include examples in diverse animal species. Over the past several decades, scientists have repeatedly debated whether human sex ratios also significantly deviate toward one sex or the other based on environmental or social conditions. An increasing number of studies supports the idea that exposure to stressful conditions can influence the sexes of offspring produced by humans, a majority of which document significantly fewer males after exposure to adverse conditions such as severe life events, economic disruption, or natural disasters. From a comparative standpoint, these findings are similar to studies in non-human mammals and other vertebrate species showing a bias toward females during times of stress. However, the mechanisms by which stress-related biases in the offspring sex ratio may occur remain elusive, and the involvement of glucocorticoids indicating a true influence of stress itself remains unstudied. Here, I review the evidence that stressful events induce sex ratio adjustment in humans. Additionally, I discuss the possibility for glucocorticoid mediation of sex ratio adjustment and the potential reproductive stages during which stress-induced sex ratio adjustment may occur in humans and other mammals.
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Affiliation(s)
- Kristen J Navara
- Department of Poultry Science, The University of Georgia, 203 Poultry Science Building, 110 Cedar Street, Athens, GA 30605, USA.
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Serum testosterone in females exposed to natural sour gas with respect to polymorphisms of XRCC1, GSTM1, and GSTT1. Mol Biol Rep 2010; 38:89-94. [DOI: 10.1007/s11033-010-0081-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 03/05/2010] [Indexed: 11/26/2022]
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Dunn E, Kapoor A, Leen J, Matthews SG. Prenatal synthetic glucocorticoid exposure alters hypothalamic-pituitary-adrenal regulation and pregnancy outcomes in mature female guinea pigs. J Physiol 2010; 588:887-99. [PMID: 20064858 DOI: 10.1113/jphysiol.2009.182139] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Preterm delivery occurs in approximately 10% of all pregnancies. Prenatal exposure to synthetic glucocorticoids (sGCs) reduces the incidence of respiratory distress syndrome (RDS) in these babies. Therefore, administration of multiple courses of sGCs became common practice. Animal and human studies have demonstrated that multiple courses of sGCs can have long-term effects. While the majority of animal studies have been undertaken in male offspring, it is emerging that there are profound sex differences in the consequences of prenatal sGC exposure. To our knowledge, no studies have determined the effects of prenatal sGC exposure on hypothalamic-pituitary-adrenal (HPA) axis function in female offspring while accounting for reproductive cycle status, or determined if there are effects on pregnancy parameters. Pregnant guinea pigs were administered three courses of betamethasone (Beta), dexamethasone (Dex) or vehicle on gestational days 40/41, 50/51 and 60/61. In adulthood (age range: postnatal days 126-165), basal and activated HPA axis function were assessed at various stages of the reproductive cycle. The female offspring were then mated and underwent an undisturbed pregnancy. Females were killed in the luteal phase of the reproductive cycle following litter weaning, and molecular analysis undertaken. In the luteal phase, Beta-exposed females exhibited significantly lower basal salivary cortisol levels (P < 0.05). Dex-exposed females also exhibited significantly lower basal salivary cortisol levels during the luteal phase (P < 0.05), but increased basal salivary cortisol levels during the ostrous phase (P < 0.01). The Beta-exposed females exhibited increased glucocorticoid receptor (GR) mRNA expression in the CA1/2 region of the hippocampus (P < 0.05) and MC2R mRNA in the adrenal cortex (P < 0.05). The Dex-exposed animals exhibited higher hippocampal GR and mineralocorticoid receptor (MR) mRNA levels (P < 0.05). Beta-exposed females showed reduced fecundity (P < 0.05). In Dex-exposed females there was a lower male to female sex ratio. In conclusion, prenatal sGC exposure affects HPA axis activity, in a cycle-dependent manner, and long-term reproductive success. The clinical implications of the findings on endocrine function and pregnancy in females are profound and further follow-up is warranted in human cohorts. Furthermore, we have shown there are considerable difference in phenotypes between the Beta- and Dex-exposed females and the specific endocrine and maternal outcome is contingent on the specific sGCs administered during pregnancy.
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Affiliation(s)
- Elizabeth Dunn
- Department of Physiology, Faculty of Medicine, University of Toronto, Medical Sciences Building, Toronto, Ontario, Canada
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García-Herreros M, Bermejo-Álvarez P, Rizos D, Gutiérrez-Adán A, Fahey AG, Lonergan P. Intrafollicular testosterone concentration and sex ratio in individually cultured bovine embryos. Reprod Fertil Dev 2010; 22:533-8. [DOI: 10.1071/rd09157] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/17/2009] [Indexed: 11/23/2022] Open
Abstract
Recent studies have suggested a relationship between bovine follicular fluid testosterone concentration and the likelihood of the oocyte being fertilised by an X- or Y-bearing spermatozoon; however, this theory has been challenged. To further test this hypothesis, follicles were dissected from the ovaries of slaughtered heifers, measured and carefully ruptured. The cumulus–oocyte complex (COC) was removed and the follicular fluid collected and testosterone concentration determined by radioimmunoassay. COCs were matured, fertilised and cultured in an individually identifiable manner; all cleaved embryos (2- to 4-cell stage, n = 164) had their sex determined by PCR. Testosterone concentrations were positively skewed. There was no significant difference between follicular fluid testosterone concentrations in male and female embryos (mean ± s.e.m. 51.5 ± 5.59 and 49.5 ± 7.42 ng mL–1, respectively). Linear, quadratic and cubic logistical regression showed that follicular testosterone concentration could not reliably predict the sex of the embryo with odds ratios of 1.001, 1.013 and 1.066, repectively, and coefficient of determination (R2) values of 0.0003, 0.0126 and 0.0567, respectively. Follicular size and testosterone concentration were not related (R2 = 0.087). Finally, follicular size had no influence on embryo sex determination (P = 0.70). In conclusion, under the conditions of the present study, the likelihood of an oocyte being fertilised by an X- or Y-bearing spermatozoon was not affected by the size of the follicle from which it was derived, nor by the testosterone concentration in the follicular fluid.
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Rodríguez PEA, Sanchez MS. Maternal exposure to triclosan impairs thyroid homeostasis and female pubertal development in Wistar rat offspring. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2010; 73:1678-88. [PMID: 21058171 DOI: 10.1080/15287394.2010.516241] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Although the effects of triclosan have been examined in male reproductive functions, it is unknown whether this potent antibacterial agent affects pregnancy and female pubertal development. Effects of maternal exposure to triclosan on thyroid homeostasis (TH) and reproductive-tract development in female Wistar rats were thus studied. Dams were exposed daily to triclosan (0, 1, 10, or 50 mg/kg/d) from 8 d before mating to lactation day 21. Offspring were also exposed after weaning. In vivo triclosan estrogenic activity was screened by uterotrophic assay and vaginal opening (VO), with first estrus and uterus and ovarian weight determined in offspring. Dam blood samples were taken during pregnancy and lactation to examine the effect of triclosan on TH. No apparent external signs of toxicity or differences in mean numbers of implantation sites were observed in treated rats. Triclosan treatment decreased total serum T(4) and T(3) in pregnant rats and also lowered sex ratio, lowered pup body weights on postnatal day (PND) 20, and delayed VO in offspring. In addition, the highest dose of triclosan significantly reduced the live birth index (percentage) and 6-d survival index. Data indicate that triclosan impairs thyroid homeostasis and reproductive toxicity in adult rats and produces fetal toxicity in offspring exposed in utero, during lactation, and after weaning.
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Affiliation(s)
- Pablo E A Rodríguez
- Subsecretaria CEPROCOR, Ministerio de Ciencia y Tecnologia, Cordoba, Argentina
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