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Invernizzi L, Bergeron P, Pelletier F, Lemaître JF, Douhard M. Sons Shorten Mother's Lifespan in Preindustrial Families with a High Level of Infant Mortality. Am Nat 2024; 204:315-326. [PMID: 39326055 DOI: 10.1086/731792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
AbstractIn dimorphic vertebrates where males are larger than females, the energetic costs of producing and rearing sons can exceed those of daughters. In humans, differences in maternal energy intake suggest that sons require 10% and 7% more energy than daughters during pregnancy and lactation, respectively. Due to a trade-off between reproduction and somatic maintenance, having sons is expected to have a more pronounced detrimental impact on a mother's lifespan than having daughters. A limitation of previous studies investigating this hypothesis is that the increased mortality cost of having sons was assumed to affect all mothers equally. Using a dataset from a preindustrial Quebec population monitored over two centuries, we found that the number of sons decreased postmenopausal lifespan only in mothers experiencing high infant mortality. Our study highlights the importance of interindividual variation in environmental conditions and maternal health when studying effects of offspring sex on reproductive costs.
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2
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Facultative and persistent offspring sex-ratio bias in relation to the social environment in cooperatively breeding red-winged fairy-wrens (Malurus elegans). Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03221-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Abstract
Females should facultatively bias offspring sex ratio when fitness returns vary among sexes. In cooperative breeders, where individuals help raise others’ young, overproducing the philopatric sex will be adaptive when helpers are absent, whereas overproducing the dispersive sex may be adaptive to reduce intrasexual competition. Thus, fitness returns are expected to vary with the social environment. However, any offspring sex-ratio biases may also result from consistent among-female differences (e.g. quality) and/or environmental variables (e.g. food availability). Yet, few studies have disentangled facultative from persistent biases. We investigated offspring sex-ratio biases in relation to the social environment in cooperatively breeding red-winged fairy-wrens (Malurus elegans). Repeated observations of the same females over nine years allowed for disentanglement of facultative from persistent biases. Females without help did not overproduce daughters, despite female helpers being associated with higher fledgling survival (resource enhancement hypothesis). Instead, females without helpers facultatively overproduced sons —the slower dispersing sex— thereby ensuring long-term helper availability. Furthermore, offspring sex ratio was not biased towards the rarer sex of helpers present in the group or population (resource competition hypothesis). However, females with sex-biased helping produced similarly skewed offspring sex ratios. This among-female association may not be surprising, because helpers are previous seasons’ offspring. Thus, in addition to facultative responses to prevailing social conditions, we found evidence for persistent biases among females. This could potentially explain previous evidence for resource competition/enhancement that have typically been interpreted as facultative responses, highlighting the need for a within-female approach to better understand the adaptiveness of sex-ratio biases.
Significance statement
Under certain conditions, females may benefit from producing a biased offspring sex ratio, but evidence for such effects in vertebrates is weak and inconsistent. Here, using observations of the same females under different social conditions, we show that cooperatively breeding red-winged fairy-wrens facultatively biased offspring sex ratio towards sons when living in pairs, thereby ensuring the availability of a workforce to assist in raising future offspring. However, biased offspring sex ratio patterns may also be the result of consistent differences among females. Indeed, we also found evidence for such patterns and suggest that this could be an explanation for previous findings which are often interpreted as facultative responses.
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3
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Hagen R, Ortmann S, Elliger A, Arnold J. Evidence for a male‐biased sex ratio in the offspring of a large herbivore: The role of environmental conditions in the sex ratio variation. Ecol Evol 2022; 12:e8938. [PMID: 35600697 PMCID: PMC9120210 DOI: 10.1002/ece3.8938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 04/13/2022] [Accepted: 05/03/2022] [Indexed: 01/21/2023] Open
Abstract
Numerous studies have examined whether the primary and/or secondary sex ratio in mammals, including humans, deviates from an equilibrium of 1:1. Although effect size in the sex ratio variation is expected to be low, a large sample size allows the identification of even small deviations from parity. In this study, we investigated whether the sex ratio of roe deer (Capreolus capreolus) offspring at birth approaches parity, using a large data set from roe deer offspring tagged in Baden‐Württemberg (Germany, 1972–2019, N = 12,437). In addition, a systematic re‐analysis of available data on the secondary sex ratios of roe deer was conducted to test whether our finding withstood the accumulation of further data. The null hypothesis that the sex ratio of roe deer (prenatal sex ratio and sex ratio at birth) approaches parity was rejected. Moreover, the secondary sex ratio of roe deer offspring deviated from the male‐biased mean for relatively cold or warm weather conditions during autumn and winter. Our study provides strong evidence for a male‐biased sex ratio in a large herbivore and weak evidence for variations in the secondary sex ratio owing to environmental conditions. The pattern is highly relevant in the context of climate change and its impact on the population dynamics of large herbivores.
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Affiliation(s)
- Robert Hagen
- Leibniz Institute for Zoo and Wildlife Research Berlin Germany
- Wildlife Research Unit Agricultural Centre Baden‐Württemberg Aulendorf Germany
| | - Sylvia Ortmann
- Leibniz Institute for Zoo and Wildlife Research Berlin Germany
| | - Andreas Elliger
- Wildlife Research Unit Agricultural Centre Baden‐Württemberg Aulendorf Germany
| | - Janosch Arnold
- Wildlife Research Unit Agricultural Centre Baden‐Württemberg Aulendorf Germany
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4
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Schwanz LE, Gunderson A, Iglesias-Carrasco M, Johnson MA, Kong JD, Riley J, Wu NC. Best practices for building and curating databases for comparative analyses. J Exp Biol 2022; 225:274297. [PMID: 35258608 DOI: 10.1242/jeb.243295] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Comparative analyses have a long history of macro-ecological and -evolutionary approaches to understand structure, function, mechanism and constraint. As the pace of science accelerates, there is ever-increasing access to diverse types of data and open access databases that are enabling and inspiring new research. Whether conducting a species-level trait-based analysis or a formal meta-analysis of study effect sizes, comparative approaches share a common reliance on reliable, carefully curated databases. Unlike many scientific endeavors, building a database is a process that many researchers undertake infrequently and in which we are not formally trained. This Commentary provides an introduction to building databases for comparative analyses and highlights challenges and solutions that the authors of this Commentary have faced in their own experiences. We focus on four major tips: (1) carefully strategizing the literature search; (2) structuring databases for multiple use; (3) establishing version control within (and beyond) your study; and (4) the importance of making databases accessible. We highlight how one's approach to these tasks often depends on the goal of the study and the nature of the data. Finally, we assert that the curation of single-question databases has several disadvantages: it limits the possibility of using databases for multiple purposes and decreases efficiency due to independent researchers repeatedly sifting through large volumes of raw information. We argue that curating databases that are broader than one research question can provide a large return on investment, and that research fields could increase efficiency if community curation of databases was established.
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Affiliation(s)
- Lisa E Schwanz
- Evolution and Ecology Research Centre, and the School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2035, Australia
| | - Alex Gunderson
- School of Science and Engineering, Tulane University, New Orleans, LA 70118, USA
| | - Maider Iglesias-Carrasco
- Ecology and Evolution of Sexual Interactions group, Doñana Biological Station-CSIC, Sevilla 41001, Spain
| | - Michele A Johnson
- Department of Biology, Trinity University, San Antonio, TX 78212, USA
| | - Jacinta D Kong
- School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - Julia Riley
- Department of Biology, Mount Allison University, Sackville, New Brunswick, E4L 1E4, Canada
| | - Nicholas C Wu
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
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5
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O'Dea RE, Lagisz M, Jennions MD, Koricheva J, Noble DW, Parker TH, Gurevitch J, Page MJ, Stewart G, Moher D, Nakagawa S. Preferred reporting items for systematic reviews and meta-analyses in ecology and evolutionary biology: a PRISMA extension. Biol Rev Camb Philos Soc 2021; 96:1695-1722. [PMID: 33960637 PMCID: PMC8518748 DOI: 10.1111/brv.12721] [Citation(s) in RCA: 129] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 04/05/2021] [Accepted: 04/08/2021] [Indexed: 12/29/2022]
Abstract
Since the early 1990s, ecologists and evolutionary biologists have aggregated primary research using meta-analytic methods to understand ecological and evolutionary phenomena. Meta-analyses can resolve long-standing disputes, dispel spurious claims, and generate new research questions. At their worst, however, meta-analysis publications are wolves in sheep's clothing: subjective with biased conclusions, hidden under coats of objective authority. Conclusions can be rendered unreliable by inappropriate statistical methods, problems with the methods used to select primary research, or problems within the primary research itself. Because of these risks, meta-analyses are increasingly conducted as part of systematic reviews, which use structured, transparent, and reproducible methods to collate and summarise evidence. For readers to determine whether the conclusions from a systematic review or meta-analysis should be trusted - and to be able to build upon the review - authors need to report what they did, why they did it, and what they found. Complete, transparent, and reproducible reporting is measured by 'reporting quality'. To assess perceptions and standards of reporting quality of systematic reviews and meta-analyses published in ecology and evolutionary biology, we surveyed 208 researchers with relevant experience (as authors, reviewers, or editors), and conducted detailed evaluations of 102 systematic review and meta-analysis papers published between 2010 and 2019. Reporting quality was far below optimal and approximately normally distributed. Measured reporting quality was lower than what the community perceived, particularly for the systematic review methods required to measure trustworthiness. The minority of assessed papers that referenced a guideline (~16%) showed substantially higher reporting quality than average, and surveyed researchers showed interest in using a reporting guideline to improve reporting quality. The leading guideline for improving reporting quality of systematic reviews is the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Here we unveil an extension of PRISMA to serve the meta-analysis community in ecology and evolutionary biology: PRISMA-EcoEvo (version 1.0). PRISMA-EcoEvo is a checklist of 27 main items that, when applicable, should be reported in systematic review and meta-analysis publications summarising primary research in ecology and evolutionary biology. In this explanation and elaboration document, we provide guidance for authors, reviewers, and editors, with explanations for each item on the checklist, including supplementary examples from published papers. Authors can consult this PRISMA-EcoEvo guideline both in the planning and writing stages of a systematic review and meta-analysis, to increase reporting quality of submitted manuscripts. Reviewers and editors can use the checklist to assess reporting quality in the manuscripts they review. Overall, PRISMA-EcoEvo is a resource for the ecology and evolutionary biology community to facilitate transparent and comprehensively reported systematic reviews and meta-analyses.
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Affiliation(s)
- Rose E. O'Dea
- Evolution & Ecology Research Centre and School of Biological and Environmental SciencesUniversity of New South WalesSydneyNSW2052Australia
| | - Malgorzata Lagisz
- Evolution & Ecology Research Centre and School of Biological and Environmental SciencesUniversity of New South WalesSydneyNSW2052Australia
| | - Michael D. Jennions
- Research School of BiologyAustralian National University46 Sullivans Creek RoadCanberra2600Australia
| | - Julia Koricheva
- Department of Biological SciencesRoyal Holloway University of LondonEghamSurreyTW20 0EXU.K.
| | - Daniel W.A. Noble
- Evolution & Ecology Research Centre and School of Biological and Environmental SciencesUniversity of New South WalesSydneyNSW2052Australia
- Research School of BiologyAustralian National University46 Sullivans Creek RoadCanberra2600Australia
| | | | - Jessica Gurevitch
- Department of Ecology and EvolutionStony Brook UniversityStony BrookNY11794‐5245U.S.A.
| | - Matthew J. Page
- School of Public Health and Preventative MedicineMonash UniversityMelbourneVIC3004Australia
| | - Gavin Stewart
- School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUU.K.
| | - David Moher
- Centre for Journalology, Clinical Epidemiology ProgramOttawa Hospital Research InstituteGeneral Campus, 501 Smyth Road, Room L1288OttawaONK1H 8L6Canada
| | - Shinichi Nakagawa
- Evolution & Ecology Research Centre and School of Biological and Environmental SciencesUniversity of New South WalesSydneyNSW2052Australia
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Augstenová B, Pensabene E, Veselý M, Kratochvíl L, Rovatsos M. Are Geckos Special in Sex Determination? Independently Evolved Differentiated ZZ/ZW Sex Chromosomes in Carphodactylid Geckos. Genome Biol Evol 2021; 13:evab119. [PMID: 34051083 PMCID: PMC8290109 DOI: 10.1093/gbe/evab119] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2021] [Indexed: 12/20/2022] Open
Abstract
Amniotes possess astonishing variability in sex determination ranging from environmental sex determination (ESD) to genotypic sex determination (GSD) with highly differentiated sex chromosomes. Geckos are one of the few amniote groups with substantial variability in sex determination. What makes them special in this respect? We hypothesized that the extraordinary variability of sex determination in geckos can be explained by two alternatives: 1) unusual lability of sex determination, predicting that the current GSD systems were recently formed and are prone to turnovers; and 2) independent transitions from the ancestral ESD to later stable GSD, which assumes that geckos possessed ancestrally ESD, but once sex chromosomes emerged, they remain stable in the long term. Here, based on genomic data, we document that the differentiated ZZ/ZW sex chromosomes evolved within carphodactylid geckos independently from other gekkotan lineages and remained stable in the genera Nephrurus, Underwoodisaurus, and Saltuarius for at least 15 Myr and potentially up to 45 Myr. These results together with evidence for the stability of sex chromosomes in other gekkotan lineages support more our second hypothesis suggesting that geckos do not dramatically differ from the evolutionary transitions in sex determination observed in the majority of the amniote lineages.
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Affiliation(s)
- Barbora Augstenová
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Eleonora Pensabene
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Milan Veselý
- Department of Zoology, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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7
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Heinsohn R, Au J, Kokko H, Webb MH, Deans RM, Crates R, Stojanovic D. Can an introduced predator select for adaptive sex allocation? Proc Biol Sci 2021; 288:20210093. [PMID: 33906398 PMCID: PMC8080011 DOI: 10.1098/rspb.2021.0093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/31/2021] [Indexed: 11/12/2022] Open
Abstract
Most species produce equal numbers of sons and daughters, and sex differences in survival after parental care do not usually affect this pattern. Temporary overproduction of the scarcer sex can be adaptive when generations overlap, the sexes differ in life-history expectations, and parents can anticipate future mating opportunities. However, an alternative strategy of maximizing the competitiveness of the more abundant sex in these circumstances remains unexplored. We develop theory showing how mothers can maximize reproductive value when future mate competition will be high by producing more sons in the advantageous early hatching positions within their broods. Our model for optimal birth order was supported by long-term data of offspring sex in a parrot facing catastrophic female mortality caused by introduced predators. Swift parrots (Lathamus discolor) suffer high female mortality due to introduced sugar gliders (Petaurus breviceps) creating fluctuating male-biased adult sex ratios. Offspring hatched early within broods fledged in better condition, and in support of our model were more likely to be male in years with higher adult female mortality. We found a highly significant rank-order correlation between observed and predicted birth sex ratios. Our study shows the potential for mothers to maximize reproductive value via strategic biases in offspring sex depending on the advantages conferred by birth order and the predictability of future mate competition. Our long-term data support the predictions and appear to suggest that sex allocation strategies may evolve surprisingly quickly when anthropogenic pressures on populations are severe.
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Affiliation(s)
- R. Heinsohn
- Fenner School of Environment and Society, Australian National University, Canberra A.C.T. 0200, Australia
| | - J. Au
- Fenner School of Environment and Society, Australian National University, Canberra A.C.T. 0200, Australia
| | - H. Kokko
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - M. H. Webb
- Fenner School of Environment and Society, Australian National University, Canberra A.C.T. 0200, Australia
| | - R. M. Deans
- Research School of Biology, Australian National University, Canberra A.C.T. 0200, Australia
| | - R. Crates
- Fenner School of Environment and Society, Australian National University, Canberra A.C.T. 0200, Australia
| | - D. Stojanovic
- Fenner School of Environment and Society, Australian National University, Canberra A.C.T. 0200, Australia
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8
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Defolie C, Merkling T, Fichtel C. Patterns and variation in the mammal parasite-glucocorticoid relationship. Biol Rev Camb Philos Soc 2020; 95:74-93. [PMID: 31608587 DOI: 10.1111/brv.12555] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 08/23/2019] [Accepted: 09/03/2019] [Indexed: 01/24/2023]
Abstract
Parasites are ubiquitous and can strongly affect their hosts through mechanisms such as behavioural changes, increased energetic costs and/or immunomodulation. When parasites are detrimental to their hosts, they should act as physiological stressors and elicit the release of glucocorticoids. Alternatively, previously elevated glucocorticoid levels could facilitate parasite infection due to neuroimmunomodulation. However, results are equivocal, with studies showing either positive, negative or no relationship between parasite infection and glucocorticoid levels. Since factors such as parasite type, infection severity or host age and sex can influence the parasite-glucocorticoid relationship, we review the main mechanisms driving this relationship. We then perform a phylogenetic meta-analysis of 110 records from 65 studies in mammalian hosts from experimental and observational studies to quantify the general direction of this relationship and to identify ecological and methodological drivers of the observed variability. Our review produced equivocal results concerning the direction of the relationship, but there was stronger support for a positive relationship, although causality remained unclear. Mechanisms such as host manipulation for parasite survival, host response to infection, cumulative effects of multiple stressors, and neuro-immunomodulatory effects of glucocorticoids could explain the positive relationship. Our meta-analysis results revealed an overall positive relationship between glucocorticoids and parasitism among both experimental and observational studies. Because all experimental studies included were parasite manipulations, we conclude that parasites caused in general an increase in glucocorticoid levels. To obtain a better understanding of the directionality of this link, experimental manipulation of glucocorticoid levels is now required to assess the causal effects of high glucocorticoid levels on parasite infection. Neither parasite type, the method used to assess parasite infection nor phylogeny influenced the relationship, and there was no evidence for publication bias. Future studies should attempt to be as comprehensive as possible, including moderators potentially influencing the parasite-glucocorticoid relationship. We particularly emphasise the importance of testing hosts of a broad age range, concomitantly measuring sex hormone levels or at least reproductive status, and for observational studies, also considering food availability, host body condition and social stressors to obtain a better understanding of the parasite-glucocorticoid relationship.
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Affiliation(s)
- Charlotte Defolie
- Sociobiology/Anthropology Department, University of Göttingen, Kellnerweg 6, 37077, Göttingen, Germany.,Behavioral Ecology & Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077, Göttingen, Germany.,Leibniz ScienceCampus "Primate Cognition", German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany
| | - Thomas Merkling
- Department of Natural Resource Sciences, McGill University, Macdonald-Stewart Building, 21111 Lakeshore Road, Ste. Anne de Bellevue, Québec, H9X 3V9, Canada
| | - Claudia Fichtel
- Behavioral Ecology & Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077, Göttingen, Germany.,Leibniz ScienceCampus "Primate Cognition", German Primate Center, Kellnerweg 4, 37077, Göttingen, Germany
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9
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James WH, Grech V. Is exposure to high levels of maternal intrauterine testosterone a causal factor common to male sex, autism, gender dysphoria, and non-right-handedness? Early Hum Dev 2020; 141:104872. [PMID: 31492544 DOI: 10.1016/j.earlhumdev.2019.104872] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We present evidence that male sex, autism, gender dysphoria and non-right-handedness share a common cause, viz. high levels of maternal first-trimester intrauterine testosterone. This provides an explanation for the (as yet unexplained) co-occurrences and co-morbidities between these conditions and pathologies.
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Affiliation(s)
- William H James
- Galton Laboratory, Department of Genetics, Evolution and Environment, University College London, United Kingdom of Great Britain and Northern Ireland.
| | - Victor Grech
- Department of Paediatrics, Medical School, Mater Dei Hospital, Malta.
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10
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James WH, Grech V. The significance of the low sex ratios of offspring and of sibs of probands with systemic lupus erythematosus or rheumatoid arthritis. Early Hum Dev 2020; 141:104871. [PMID: 31492546 DOI: 10.1016/j.earlhumdev.2019.104871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
There is good evidence that there are significantly low sex ratios (proportions male) in the offspring of patients with some immune diseases e.g. systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). There is also strong evidence that there are significantly low sex ratios in the sibs of patients with SLE and RA and it has been suggested that the low SLE sib sex ratio may be explained by male fetal loss. However, no explanations for these low sex ratios has been established. Bearing in mind the posited hormonal involvement in immune processes, this paper suggesst an additional potential solution. It is that both the pathology and the sex ratio share a hormonal cause - testosterone. The argument depends on the hormonal hypothesis of sex ratio. This paper will describe the hypothesis and describe its relevance to SLE and RA.
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Affiliation(s)
- William H James
- Galton Laboratory, Department of Genetics, Evolution and Environment, University College London.
| | - Victor Grech
- Department of Paediatrics, Medical School, Mater Dei Hospital, Malta.
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11
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Lavoie MD, Tedeschi JN, Garcia‐Gonzalez F, Firman RC. Exposure to male-dominated environments during development influences sperm sex ratios at sexual maturity. Evol Lett 2019; 3:392-402. [PMID: 31388448 PMCID: PMC6675145 DOI: 10.1002/evl3.123] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/15/2019] [Accepted: 05/21/2019] [Indexed: 11/18/2022] Open
Abstract
Different stages during development are important when it comes to phenotypic adjustments in response to external stimuli. Critical stages in mammals are the prenatal phase, where embryos are exposed to a milieu of sex steroid hormones, and the early-postnatal phase, where littermates interact and experience their incipient social environment. Further, the postmaternal environment will influence the development of traits that are linked to reproductive success in adulthood. Accumulated evidence of male-driven sex allocation establishes the currently untested hypothesis that the sperm sex ratio is a plastic trait that can be mediated to align with prevailing social conditions. Here, we used natural variation in the maternal environment and experimentally manipulated the postmaternal environment to identify the importance of these developmental phases on sperm sex ratio adjustments in wild house mice (Mus musculus domesticus). We found that male density in both environments was predictive of sperm sex ratios at sexual maturity: males from more male-biased litters and males maturing under high male density produced elevated levels of Y-chromosome-bearing sperm. Our findings indicate that the sperm sex ratio is a variable phenotypic trait that responds to the external environment, and highlight the potential that these adjustments function as a mechanism of male-driven sex allocation.
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Affiliation(s)
- Misha D. Lavoie
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
| | - Jamie N. Tedeschi
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
| | - Francisco Garcia‐Gonzalez
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
- Estacion Biológica de DoñanaCSICSevillaSpain
| | - Renée C. Firman
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
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12
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Merkling T, Hatch SA, Leclaire S, Danchin E, Blanchard P. Offspring sex-ratio and environmental conditions in a seabird with sex-specific rearing costs: a long-term experimental approach. Evol Ecol 2019. [DOI: 10.1007/s10682-019-09983-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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