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Brown ER, Gettler LT, Rosenbaum S. Effects of social environments on male primate HPG and HPA axis developmental programming. Dev Psychobiol 2024; 66:e22491. [PMID: 38698633 DOI: 10.1002/dev.22491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 03/05/2024] [Accepted: 04/07/2024] [Indexed: 05/05/2024]
Abstract
Developmental plasticity is particularly important for humans and other primates because of our extended period of growth and maturation, during which our phenotypes adaptively respond to environmental cues. The hypothalamus-pituitary-gonadal (HPG) and hypothalamus-pituitary-adrenal (HPA) axes are likely to be principal targets of developmental "programming" given their roles in coordinating fitness-relevant aspects of the phenotype, including sexual development, adult reproductive and social strategies, and internal responses to the external environment. In social animals, including humans, the social environment is believed to be an important source of cues to which these axes may adaptively respond. The effects of early social environments on the HPA axis have been widely studied in humans, and to some extent, in other primates, but there are still major gaps in knowledge specifically relating to males. There has also been relatively little research examining the role that social environments play in developmental programming of the HPG axis or the HPA/HPG interface, and what does exist disproportionately focuses on females. These topics are likely understudied in males in part due to the difficulty of identifying developmental milestones in males relative to females and the general quiescence of the HPG axis prior to maturation. However, there are clear indicators that early life social environments matter for both sexes. In this review, we examine what is known about the impact of social environments on HPG and HPA axis programming during male development in humans and nonhuman primates, including the role that epigenetic mechanisms may play in this programming. We conclude by highlighting important next steps in this research area.
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Affiliation(s)
- Ella R Brown
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lee T Gettler
- Department of Anthropology, University of Notre Dame, Notre Dame, Indiana, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Stacy Rosenbaum
- Department of Anthropology, University of Michigan, Ann Arbor, Michigan, USA
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2
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Kumar S, Song R, Mishra JS. Elevated gestational testosterone impacts vascular and uteroplacental function. Placenta 2023:S0143-4004(23)00598-2. [PMID: 37977936 PMCID: PMC11087376 DOI: 10.1016/j.placenta.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/04/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
Maternal vascular adaptations to establish an adequate blood supply to the uterus and placenta are essential for optimal nutrient and oxygen delivery to the developing fetus in eutherian mammals, including humans. Numerous factors contribute to maintaining appropriate hemodynamics and placental vascular development throughout pregnancy. Failure to achieve or sustain these pregnancy-associated changes in women is strongly associated with an increased risk of antenatal complications, such as preeclampsia, a hypertensive disorder of pregnancy. The precise etiology of preeclampsia is unknown, but emerging evidence points to a potential role for androgens. The association between androgens and maternal cardiovascular and placental function merits particular attention due to the notable 2- to 3-fold elevated plasma testosterone (T) levels observed in preeclampsia. T levels in preeclamptic women positively correlate with vascular dysfunction, and preeclampsia is associated with increased androgen receptor (AR) levels in placental tissues. Moreover, animal studies replicating the pattern and magnitude of T increase observed in preeclamptic pregnancies have reproduced key features of preeclampsia, including gestational hypertension, endothelial dysfunction, heightened vasoconstriction to angiotensin II, impaired spiral artery remodeling, placental hypoxia, reduced nutrient transport, and fetal growth restriction. Collectively, these findings suggest that AR-mediated activity plays a significant role in the clinical presentation of preeclampsia. This review critically evaluates this hypothesis, considering both clinical and preclinical evidence.
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Affiliation(s)
- Sathish Kumar
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, 53706, USA; Department of Obstetrics and Gynecology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, 53792, USA.
| | - Ruolin Song
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, 53706, USA
| | - Jay S Mishra
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, 53706, USA
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3
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Naidu SJ, Arangasamy A, Selvaraju S, Binsila BK, Reddy IJ, Ravindra JP, Bhatta R. Maternal influence on the skewing of offspring sex ratio: a review. ANIMAL PRODUCTION SCIENCE 2022. [DOI: 10.1071/an21086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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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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5
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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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6
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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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7
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Fight or flight? Effects of vaginal oestrus on cortisol, testosterone, and behaviour in guinea pig female-female interaction. Behav Processes 2018; 157:625-631. [PMID: 29654828 DOI: 10.1016/j.beproc.2018.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 03/28/2018] [Accepted: 04/09/2018] [Indexed: 11/21/2022]
Abstract
It is accepted that social stress in relation to confrontation and competition can elicit behavioural and hormonal changes in social mammals. These effects have, however, been less frequently studied among female-female interactions. In the present study female-female confrontation experiments were carried out to monitor socio-positive and agonistic behaviour by controlling for the oestrus cycles of 12 individuals. Additionally, plasma cortisol (CORT) and testosterone (T) levels were determined before and after the experiments. During non-oestrus conditions a significant increase in CORT levels from pre- to post confrontation was registered and females spent more time to sit side by side. During vaginal oestrus the confrontation experiments revealed avoiding of a conspecific female by showing increased flight behaviour. However, during that period no changes in CORT levels were found. But, a non-significant increase in T was measured from pre- to post confrontation in both cycle phases, while no differences in the display of aggressive behaviours were found. These findings indicate considerable influences of different oestrus cycle phases on social stress-induced CORT secretion and the modulation of socio-positive and agonistic behaviour in female guinea pigs.
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9
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Abstract
The human sex ratio (proportion male) at birth (SRB) varies with many variables. Some of this variation has an established proximate cause. For instance, low SRB (more females) at birth are associated with various forms of stressful events or circumstances during or prior to pregnancy. These low SRB are almost certainly mainly caused by maternal-stress-induced male foetal loss. Other types of SRB variation are thought to be caused by hormonal variation in either or both parents around the time of conception. One or other of these two types of proximate cause seems to be responsible for most of the established variation of SRB. This will be illustrated here in respect of some selected forms of SRB variation. It seems likely that a clarification of the hormonal causes of SRB variation will also help explain the striking (apparent) inconsistencies in the results of reported tests of the influential Trivers-Willard hypothesis. It is further proposed that an appreciation of the evidence that parental hormones influence SRB may enhance understanding of several important pathologies (hepatitis B, toxoplasmosis, testicular cancer, prostate cancer and autism).
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Affiliation(s)
- William H James
- The Galton Laboratory, Department of Genetics, Evolution and Environment, University College London, United Kingdom.
| | - Victor Grech
- Department of Paediatrics, Mater Dei Hospital Medical School, Malta.
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10
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Setchell JM. Sexual Selection and the differences between the sexes in Mandrills (Mandrillus sphinx). AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 159:S105-29. [PMID: 26808101 DOI: 10.1002/ajpa.22904] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sexual selection has become a major focus in evolutionary and behavioral ecology. It is also a popular research topic in primatology. I use studies of mandrills (Mandrillus sphinx), a classic example of extravagant armaments and ornaments in animals, to exemplify how a long-term, multidisciplinary approach that integrates field observations with laboratory methods can contribute to on-going theoretical debates in the field of sexual selection. I begin with a brief summary of the main concepts of sexual selection theory and the differences between the sexes. I then introduce mandrills and the study population and review mandrill life history, the ontogeny of sex differences, and maternal effects. Next, I focus on male-male competition and female choice, followed by the less well-studied questions of female-female competition and male choice. This review shows how different reproductive priorities lead to very different life histories and divergent adaptations in males and females. It demonstrates how broadening traditional perspectives on sexual selection beyond the ostentatious results of intense sexual selection on males leads to an understanding of more subtle and cryptic forms of competition and choice in both sexes and opens many productive avenues in the study of primate reproductive strategies. These include the potential for studies of postcopulatory selection, female intrasexual competition, and male choice. These studies of mandrills provide comparison and, I hope, inspiration for studies of both other polygynandrous species and species with mating systems less traditionally associated with sexual selection.
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Affiliation(s)
- Joanna M Setchell
- Department of Anthropology, Evolutionary Anthropology Research Group, Behaviour Ecology and Evolution Research (BEER) Centre, Durham University, Durham, DH1 3LE, UK
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11
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Arnon L, Hazut N, Tabachnik T, Weller A, Koren L. Maternal testosterone and reproductive outcome in a rat model of obesity. Theriogenology 2016; 86:1042-1047. [PMID: 27125699 DOI: 10.1016/j.theriogenology.2016.03.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/15/2016] [Accepted: 03/19/2016] [Indexed: 01/22/2023]
Abstract
Global sex differences in obesity rates are persistent, suggesting the involvement of sex steroids. In addition, adipose tissue is a metabolic site for steroidogenesis. Here, we compared female reproductive parameters in a rat model of obesity, with the same parameters in its lean control strain, and tested for an association with integrated measures of corticosterone and testosterone. Steroids were extracted and quantified from 17 Otsuka Long Evans Tokushima Fatty (OLETF; an animal model for obesity) and 13 Long Evans Tokushima Otsuka (LETO; the lean control strain) hair samples that were collected after weaning offspring. The obese OLETF mothers had higher hair testosterone levels than the control LETO strain. Overall, testosterone, but not corticosterone, predicted litter sex ratios. Younger mothers with large litters and older mothers with small litters tended to have the highest sex ratios (i.e., male-biased litters). In the lean LETO strain, but not in the obese OLETF, maternal testosterone was positively associated with litter size and number of male pups. Corticosterone did not differ between the two strains and was not associated with testosterone or with reproductive parameters. This study suggests that long-term circulating testosterone is associated with female reproduction in multiple ways. The possible trade-off between litter size and sex ratio may be mediated by testosterone and influenced by body fat and composition, which influence the individual's well-being. Exploring the multiple roles of testosterone in females may also help explain the complex relationship between obesity and reproduction.
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Affiliation(s)
- Liat Arnon
- Faculty of Life Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Noa Hazut
- Faculty of Life Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel; Gonda Brain Research Center, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Tzlil Tabachnik
- Faculty of Life Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel; Gonda Brain Research Center, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Aron Weller
- Gonda Brain Research Center, Bar Ilan University, Ramat-Gan 5290002, Israel; Department of Psychology, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Lee Koren
- Faculty of Life Sciences, Bar Ilan University, Ramat-Gan 5290002, Israel.
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12
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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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13
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Sonnweber RS, Ravignani A, Stobbe N, Schiestl G, Wallner B, Fitch WT. Rank-dependent grooming patterns and cortisol alleviation in Barbary macaques. Am J Primatol 2015; 77:688-700. [DOI: 10.1002/ajp.22391] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 01/27/2015] [Accepted: 02/05/2015] [Indexed: 01/01/2023]
Affiliation(s)
- Ruth S. Sonnweber
- Department of Cognitive Biology; University of Vienna Althanstrasse 14; Vienna Austria
- Department of Behavioural Biology; University of Vienna Althanstrasse 14; Vienna Austria
| | - Andrea Ravignani
- Department of Cognitive Biology; University of Vienna Althanstrasse 14; Vienna Austria
- Language Evolution & Computation Research Unit; School of Philosophy, Psychology and Language Sciences; University of Edinburgh 3; Edinburgh United Kingdom
| | - Nina Stobbe
- Department of Cognitive Biology; University of Vienna Althanstrasse 14; Vienna Austria
| | - Gisela Schiestl
- Department of Behavioural Biology; University of Vienna Althanstrasse 14; Vienna Austria
| | - Bernard Wallner
- Department of Behavioural Biology; University of Vienna Althanstrasse 14; Vienna Austria
- Department of Anthropology; University of Vienna Althanstrasse 14; Vienna Austria
| | - W. Tecumseh Fitch
- Department of Cognitive Biology; University of Vienna Althanstrasse 14; Vienna Austria
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14
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Pluháček J, Steck BL. Different Sex Allocations in Two Related Species: The Case of the Extant Hippopotamus. Ethology 2015. [DOI: 10.1111/eth.12357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Jan Pluháček
- Department of Ethology; Institute of Animal Science; Praha - Uhříněves Czech Republic
- Ostrava Zoo; Ostrava Czech Republic
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15
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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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17
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Brief communication: Female fecal androgens prior to the mating season reflect readiness to conceive in reproductively quiescent wild macaques. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 151:311-5. [DOI: 10.1002/ajpa.22273] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/15/2013] [Indexed: 11/07/2022]
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Wallner B, Fieder M, Seidler H. Ownership of dwelling affects the sex ratio at birth in Uganda. PLoS One 2012; 7:e51463. [PMID: 23284697 PMCID: PMC3524175 DOI: 10.1371/journal.pone.0051463] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 10/25/2012] [Indexed: 11/26/2022] Open
Abstract
Background Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH). This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB) on a Ugandan sample. Methodology/Principal Findings Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019) compared to those who live in non-owned dwellings (0.458). Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers’ age, mothers’ education, parity and others. Conclusions/Significance The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.
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Affiliation(s)
- Bernard Wallner
- Department of Anthropology, University of Vienna, Vienna, Austria.
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Macke E, Magalhães S, Bach F, Olivieri I. Sex-ratio adjustment in response to local mate competition is achieved through an alteration of egg size in a haplodiploid spider mite. Proc Biol Sci 2012; 279:4634-42. [PMID: 23015625 PMCID: PMC3479724 DOI: 10.1098/rspb.2012.1598] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 09/04/2012] [Indexed: 11/12/2022] Open
Abstract
Sex-ratio adjustments are commonly observed in haplodiploid species. However, the underlying proximate mechanisms remain elusive. We investigated these mechanisms in Tetranychus urticae, a haplodiploid spider mite known to adjust sex ratio in response to the level of local mate competition (LMC). In this species, egg size determines fertilization probability, with larger eggs being more likely to be fertilized, and thus become female. We explored the hypothesis that sex-ratio adjustment is achieved through adjustment of egg size. By using spider mites from a large population, we found that females produced not only a higher proportion of daughters under high levels of LMC, but also larger eggs. Moreover, in populations experimentally evolving under varying levels of LMC, both the proportion of females and the egg size increased with LMC intensity. These results suggest that sex-ratio adjustment in spider mites is mediated by egg size, although the causal relationship remains to be tested.
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Affiliation(s)
- Emilie Macke
- Université Montpellier 2, CNRS, IRD, UMR 5554, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Sara Magalhães
- Centro de Biologia Ambiental, Faculdade de Ciências da Universidade de Lisboa, Edificio C2, 30 Piso Campo Grande, 1749016 Lisbon, Portugal
| | - Fabien Bach
- Université Montpellier 2, CNRS, IRD, UMR 5554, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | - Isabelle Olivieri
- Université Montpellier 2, CNRS, IRD, UMR 5554, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
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Helle S, Laaksonen T, Huitu O. Sex-specific offspring growth according to maternal testosterone, corticosterone, and glucose levels. Behav Ecol 2012. [DOI: 10.1093/beheco/ars155] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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21
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Meindl K, Windhager S, Wallner B, Schaefer K. Second-to-fourth digit ratio and facial shape in boys: the lower the digit ratio, the more robust the face. Proc Biol Sci 2012; 279:2457-63. [PMID: 22337693 DOI: 10.1098/rspb.2011.2351] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
During human ontogeny, testosterone has powerful organizational and activational effects on the male organism. This has led to the hypothesis that the prenatal environment (as studied through the second-to-fourth digit ratio, 2D : 4D) is not only associated with robust adult male faces that are perceived as dominant and masculine, but also that there is an activational step during puberty. To test the latter, we collected digit ratios and frontal photographs of right-handed Caucasian boys (aged 4-11 years) along with age, body height and body weight. Using geometric morphometrics, we show a significant relationship between facial shape and 2D : 4D before the onset of puberty (explaining 14.5% of shape variation; p = 0.014 after 10 000 permutations, n = 17). Regression analyses depict the same shape patterns as in adults, namely that the lower the 2D : 4D, the smaller and shorter the forehead, the thicker the eyebrows, the wider and shorter the nose, and the larger the lower face. Our findings add to previous evidence that certain adult male facial characteristics that elicit attributions of masculinity and dominance are determined very early in ontogeny. This has implications for future studies in various fields ranging from social perception to life-history strategies.
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Affiliation(s)
- Konstanze Meindl
- Department of Anthropology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
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