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Kappeler PM, Benhaiem S, Fichtel C, Fromhage L, Höner OP, Jennions MD, Kaiser S, Krüger O, Schneider JM, Tuni C, van Schaik J, Goymann W. Sex roles and sex ratios in animals. Biol Rev Camb Philos Soc 2023; 98:462-480. [PMID: 36307924 DOI: 10.1111/brv.12915] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 10/12/2022] [Accepted: 10/14/2022] [Indexed: 11/29/2022]
Abstract
In species with separate sexes, females and males often differ in their morphology, physiology and behaviour. Such sex-specific traits are functionally linked to variation in reproductive competition, mate choice and parental care, which have all been linked to sex roles. At the 150th anniversary of Darwin's theory on sexual selection, the question of why patterns of sex roles vary within and across species remains a key topic in behavioural and evolutionary ecology. New theoretical, experimental and comparative evidence suggests that variation in the adult sex ratio (ASR) is a key driver of variation in sex roles. Here, we first define and discuss the historical emergence of the sex role concept, including recent criticisms and rebuttals. Second, we review the various sex ratios with a focus on ASR, and explore its theoretical links to sex roles. Third, we explore the causes, and especially the consequences, of biased ASRs, focusing on the results of correlational and experimental studies of the effect of ASR variation on mate choice, sexual conflict, parental care and mating systems, social behaviour, hormone physiology and fitness. We present evidence that animals in diverse societies are sensitive to variation in local ASR, even on short timescales, and propose explanations for conflicting results. We conclude with an overview of open questions in this field integrating demography, life history and behaviour.
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Affiliation(s)
- Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center - Leibniz Institute of Primatology, Kellnerweg 4, 37077, Göttingen, Germany
- Department of Sociobiology/Anthropology, University of Göttingen, Kellnerweg 6, 37077, Göttingen, Germany
| | - Sarah Benhaiem
- Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, D-10315, Berlin, Germany
| | - Claudia Fichtel
- Behavioral Ecology and Sociobiology Unit, German Primate Center - Leibniz Institute of Primatology, Kellnerweg 4, 37077, Göttingen, Germany
| | - Lutz Fromhage
- Department of Biological and Environmental Science, Ambiotica, University of Jyväskylä, PO Box 35, 40014, Jyväskylä, Finland
| | - Oliver P Höner
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, D-10315, Berlin, Germany
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, ANU College of Science, The Australian National University, RN Robertson Building, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149, Münster, Germany
| | - Oliver Krüger
- Department of Animal Behavior, Bielefeld University, Morgenbreede 45, 33615, Bielefeld, Germany
| | - Jutta M Schneider
- Department of Biology, Institute of Zoology, Universität Hamburg, Martin-Luther-King Platz 3, 20146, Hamburg, Germany
| | - Cristina Tuni
- Department of Biology II, Ludwig Maximilians University of Munich, Großhaderner Str 2, 82152, Planegg-Martinsried, Germany
| | - Jaap van Schaik
- Applied Zoology and Nature Conservation, University of Greifswald, Loitzer Str. 26, 17489, Greifswald, Germany
| | - Wolfgang Goymann
- Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, Eberhard-Gwinner-Str. 6a, D-82319, Seewiesen, Germany
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Safari I, Goymann W. The evolution of reversed sex roles and classical polyandry: Insights from coucals and other animals. Ethology 2020. [DOI: 10.1111/eth.13095] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Ignas Safari
- Max‐Planck‐Institut für Ornithologie, Abteilung für Verhaltensneurobiologie Seewiesen Germany
- Coucal Project Chimala Tanzania
- Department of Biology University of Dodoma Dodoma Tanzania
| | - Wolfgang Goymann
- Max‐Planck‐Institut für Ornithologie, Abteilung für Verhaltensneurobiologie Seewiesen Germany
- Coucal Project Chimala Tanzania
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Génin F, Masters JC. Sharing the burden: A neutral approach to socioecological theory. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 165 Suppl 65:90-103. [PMID: 29380888 DOI: 10.1002/ajpa.23383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 12/11/2017] [Indexed: 11/07/2022]
Abstract
OBJECTIVE The socioecological model (SEM) is a popular collection of controversial models purporting to explain mating systems in terms of ecological and social parameters. Despite its guise of objectivity, several of its hypotheses assume Victorian gender stereotypes of active, competing males heedlessly sowing their seeds, and cautious, passive females, imprisoned by greater costs of reproduction and their consequent resourceߚdependence. METHODS We enter this debate by taking a previously neglected explanatory approach borrowed from species theory. According to the Recognition Concept of sexual species, the unit of reproductive success/fitness is irreducible to fewer than two integrated subparts (minimally a male and a female). Phyletic changes in mating systems logically effect changes in fertilization systems, leading to reproductive isolation. We take our primary assumption of the average equivalence of female and male contributions to successful reproduction from the writings of the natural philosopher, Antoinette Blackwell. RESULTS We revisit the SEM with its contradictions and extrapolations, and develop a genderߚneutral alternative hypothesis termed SpecificߚMate Contact (SMC), centered on two fundamental mating strategies: sexual animals may behave as synchronous mateߚattractors or asynchronous mateߚseekers, generating four possible mating system combinations (monogamy: two attractors; promiscuity: two seekers; polygyny: male attractor and female seeker; polyandry: female attractor and male seeker). CONCLUSIONS Our approach predicts all known primate mating systems using a neutral (nonߚsexist) principle. The approach is also neutral in the sense that it does not invoke either competition or cooperation: fertilization success is considered a posteriori and males and females are coߚadapted to this end rather than cognitively cooperative.
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Affiliation(s)
- Fabien Génin
- African Primate Initiative for Ecology and Speciation (APIES), Earth Stewardship Science Research Institute, Nelson Mandela University, Port Elizabeth, South Africa
| | - Judith C Masters
- African Primate Initiative for Ecology and Speciation (APIES), Earth Stewardship Science Research Institute, Nelson Mandela University, Port Elizabeth, South Africa.,Department of Zoology and Entomology, University of Fort Hare, Alice, South Africa
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Goymann W, Safari I, Muck C, Schwabl I. Sex roles, parental care and offspring growth in two contrasting coucal species. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160463. [PMID: 27853561 PMCID: PMC5098986 DOI: 10.1098/rsos.160463] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/06/2016] [Indexed: 06/06/2023]
Abstract
The decision to provide parental care is often associated with trade-offs, because resources allocated to parental care typically cannot be invested in self-maintenance or mating. In most animals, females provide more parental care than males, but the reason for this pattern is still debated in evolutionary ecology. To better understand sex differences in parental care and its consequences, we need to study closely related species where the sexes differ in offspring care. We investigated parental care in relation to offspring growth in two closely related coucal species that fundamentally differ in sex roles and parental care, but live in the same food-rich habitat with a benign climate and have a similar breeding phenology. Incubation patterns differed and uniparental male black coucals fed their offspring two times more often than female and male white-browed coucals combined. Also, white-browed coucals had more 'off-times' than male black coucals, during which they perched and preened. However, these differences in parental care were not reflected in offspring growth, probably because white-browed coucals fed their nestlings a larger proportion of frogs than insects. A food-rich habitat with a benign climate may be a necessary, but-perhaps unsurprisingly-is not a sufficient factor for the evolution of uniparental care. In combination with previous results (Goymann et al. 2015 J. Evol. Biol. 28, 1335-1353 (doi:10.1111/jeb.12657)), these data suggest that white-browed coucals may cooperate in parental care, because they lack opportunities to become polygamous rather than because both parents were needed to successfully raise all offspring. Our case study supports recent theory suggesting that permissive environmental conditions in combination with a particular life history may induce sexual selection in females. A positive feedback loop among sexual selection, body size and adult sex-ratio may then stabilize reversed sex roles in competition and parental care.
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Affiliation(s)
- Wolfgang Goymann
- Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Eberhard-Gwinner-Strasse 6a, 82319 Seewiesen, Germany
- Coucal Project, PO Box 26, Chimala, Tanzania
| | - Ignas Safari
- Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Eberhard-Gwinner-Strasse 6a, 82319 Seewiesen, Germany
- Coucal Project, PO Box 26, Chimala, Tanzania
- Department of Conservation Biology, University of Dodoma, PO Box 338, Dodoma, Tanzania
| | - Christina Muck
- Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Eberhard-Gwinner-Strasse 6a, 82319 Seewiesen, Germany
| | - Ingrid Schwabl
- Max-Planck-Institut für Ornithologie, Abteilung für Verhaltensneurobiologie, Eberhard-Gwinner-Strasse 6a, 82319 Seewiesen, Germany
- Coucal Project, PO Box 26, Chimala, Tanzania
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Sharpe LL, Rubow J, Cherry MI. Robbing rivals: interference foraging competition reflects female reproductive competition in a cooperative mammal. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2015.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Goymann W, Makomba M, Urasa F, Schwabl I. Social monogamy vs. polyandry: ecological factors associated with sex roles in two closely related birds within the same habitat. J Evol Biol 2015; 28:1335-53. [DOI: 10.1111/jeb.12657] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 04/29/2015] [Accepted: 05/14/2015] [Indexed: 11/28/2022]
Affiliation(s)
- W. Goymann
- Abteilung für Verhaltensneurobiologie; Max-Planck-Institut für Ornithologie; Seewiesen Germany
- Coucal Project; Chimala Tanzania
| | | | - F. Urasa
- Department of Zoology; University of Dar es Salaam; Dar es Salaam Tanzania
| | - I. Schwabl
- Abteilung für Verhaltensneurobiologie; Max-Planck-Institut für Ornithologie; Seewiesen Germany
- Coucal Project; Chimala Tanzania
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García-Peña GE, Sol D, Iwaniuk AN, Székely T. Sexual selection on brain size in shorebirds (Charadriiformes). J Evol Biol 2013; 26:878-88. [DOI: 10.1111/jeb.12104] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/21/2012] [Accepted: 12/10/2012] [Indexed: 11/30/2022]
Affiliation(s)
| | - D. Sol
- CREAF; Cerdanyola del Vallès Spain
- CSIC; Cerdanyola del Vallès Spain
| | - A. N. Iwaniuk
- National Museum of Natural History; Smithsonian Institution; Washington DC USA
- Department of Neuroscience; Canadian Centre for Behavioural Neuroscience; University of Lethbridge; Lethbridge AB Canada
| | - T. Székely
- Department of Biology and Biochemistry; University of Bath; Bath UK
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Kosztolányi A, Barta Z, Küpper C, Székely T. Persistence of an extreme male-biased adult sex ratio in a natural population of polyandrous bird. J Evol Biol 2011; 24:1842-6. [PMID: 21749544 DOI: 10.1111/j.1420-9101.2011.02305.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a number of insects, fishes and birds, the conventional sex roles are reversed: males are the main care provider, whereas females focus on matings. The reversal of typical sex roles is an evolutionary puzzle, because it challenges the foundations of sex roles, sexual selection and parental investment theory. Recent theoretical models predict that biased parental care may be a response to biased adult sex ratios (ASRs). However, estimating ASR is challenging in natural populations, because males and females often have different detectabilities. Here, we use demographic modelling with field data from 2101 individuals, including 579 molecularly sexed offspring, to provide evidence that ASR is strongly male biased in a polyandrous bird with male-biased care. The model predicts 6.1 times more adult males than females (ASR=0.860, proportion of males) in the Kentish plover Charadrius alexandrinus. The extreme male bias is consistent between years and concordant with experimental results showing strongly biased mating opportunity towards females. Based on these results, we conjecture that parental sex-role reversal may occur in populations that exhibit extreme male-biased ASR.
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Affiliation(s)
- A Kosztolányi
- Department of Ethology, Eötvös Loránd University, Budapest, Hungary.
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Muck C, Goymann W. Throat patch size and darkness covaries with testosterone in females of a sex-role reversed species. Behav Ecol 2011. [DOI: 10.1093/beheco/arr133] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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11
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Social and coevolutionary feedbacks between mating and parental investment. Trends Ecol Evol 2010; 25:99-108. [DOI: 10.1016/j.tree.2009.07.012] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 07/07/2009] [Accepted: 07/13/2009] [Indexed: 11/21/2022]
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Abstract
Sexual selection can explain major micro- and macro-evolutionary patterns. Much of current theory predicts that the strength of sexual selection (i) is driven by the relative abundance of males and females prepared to mate (i.e. the operational sex ratio, OSR) and (ii) can be generally estimated by calculating intra-sexual variation in mating success (e.g. the opportunity for sexual selection, I(s)). Here, we demonstrate the problematic nature of these predictions. The OSR and I(s) only accurately predict sexual selection under a limited set of circumstances, and more specifically, only when mate monopolization is extremely strong. If mate monopolization is not strong, using OSR or I(s) as proxies or measures of sexual selection is expected to produce spurious results that lead to the false conclusion that sexual selection is strong when it is actually weak. These findings call into question the validity of empirical conclusions based on these measures of sexual selection.
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Affiliation(s)
- H Klug
- Department of Biological and Environmental Science, University of Helsinki, Finland.
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14
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15
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Olson VA, Liker A, Freckleton RP, Székely T. Parental conflict in birds: comparative analyses of offspring development, ecology and mating opportunities. Proc Biol Sci 2008; 275:301-7. [PMID: 18029303 DOI: 10.1098/rspb.2007.1395] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Parents often conflict over how much care to provide to their offspring. This conflict is expected to produce a negative relationship between male and female parental care, the strength of which may be mediated by both ecological and life-history variables. Previous studies have observed such trade-offs, but it is not known how generally they occur. Traditional views of sexual conflict place great importance on ecological factors in determining levels of parental care, whereas alternative views propose that the key determinant is mating opportunity. We carried out a broad-scale comparative study of parental conflict using 193 species from 41 families of birds. Using phylogenetic comparative analysis, we establish the generality of intersexual parental care conflict. We also show that parental conflict, as indicated by the disparity in care between the male and the female, depends on offspring development and mating opportunities, since in precocial species both males and females responded to increased mating opportunities. Altricial birds, however, failed to show these relationships. We also found little influence of breeding climate on parental conflict. Taken together, our results suggest that sexual conflict is a key element in the evolution of parental care systems. They also support the view that the major correlates of the intersexual conflict are mating opportunities for both sexes, rather than the breeding environment.
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Affiliation(s)
- V A Olson
- Department of Biology and Biochemistry, University of Bath, 4 South, Claverton Down, Bath BA2 7AY, UK
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Bonsall MB. The evolution of anisogamy: The adaptive significance of damage, repair and mortality. J Theor Biol 2006; 238:198-210. [PMID: 15993424 DOI: 10.1016/j.jtbi.2005.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Revised: 05/05/2005] [Accepted: 05/09/2005] [Indexed: 10/25/2022]
Abstract
Classic theory on the evolution of anisogamy focuses on the trade-off between gamete productivity and provisioning and mechanisms associated with post-zygotic survival. In this article, the role of mortality acting on both zygotes and gametes is explored as a factor influencing the evolution of different sized gametes. In particular, variable mortality through differential survival or metabolic damage is shown to affect the persistence of isogamy, the evolution of more than two sexes and the evolution of anisogamy. Evolutionary stable isogamous states are shown to be locally unstable and disruptive selection can induce the evolution of anisogamy. Analysis of both the isogamous and anisogamous ESS points reveals that the persistence of either of these conditions is not always assured. The implications of variable survival on the evolution of anisogamy are discussed.
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Affiliation(s)
- Michael B Bonsall
- Department of Biological Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK.
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Thomas GH, Székely T. EVOLUTIONARY PATHWAYS IN SHOREBIRD BREEDING SYSTEMS: SEXUAL CONFLICT, PARENTAL CARE, AND CHICK DEVELOPMENT. Evolution 2005. [DOI: 10.1554/05-226.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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