1
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Macedo-Rego RC, Jennions MD, Santos ESA. Does the potential strength of sexual selection differ between mating systems with and without defensive behaviours? A meta-analysis. Biol Rev Camb Philos Soc 2024; 99:1504-1523. [PMID: 38597347 DOI: 10.1111/brv.13078] [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: 04/10/2023] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/11/2024]
Abstract
The Darwin-Bateman paradigm predicts that females enhance their fitness by being choosy and mating with high-quality males, while males should compete to mate with as many females as possible. In many species, males enhance their fitness by defending females and/or resources used by females. That is, males directly defend access to mating opportunities. However, paternity analyses have repeatedly shown that females in most species mate polyandrously, which contradicts traditional expectations that male defensive behaviours lead to monandry. Here, in an extensive meta-analysis, encompassing 109 species and 1026 effect sizes from across the animal kingdom, we tested if the occurrence of defensive behaviours modulates sexual selection on females and males. If so, we can illuminate the extent to which males really succeed in defending access to mating and fertilisation opportunities. We used four different indices of the opportunity for sexual selection that comprise pre-mating and/or post-mating episodes of selection. We found, for both sexes, that the occurrence of defensive behaviours does not modulate the potential strength of sexual selection. This implies that male defensive behaviours do not predict the true intensity of sexual selection. While the most extreme levels of sexual selection on males are in species with male defensive behaviours, which indicates that males do sometimes succeed in restricting females' re-mating ability (e.g. elephant seals, Mirounga leonina), estimates of the opportunity for sexual selection vary greatly across species, regardless of whether or not defensive behaviours occur. Indeed, widespread polyandry shows that females are usually not restricted by male defensive behaviours. In addition, our results indicate that post-mating episodes of selection, such as cryptic female choice and sperm competition, might be important factors modulating the opportunity for sexual selection. We discuss: (i) why male defensive behaviours fail to lower the opportunity for sexual selection among females or fail to elevate it for males; (ii) how post-mating events might influence sexual selection; and (iii) the role of females as active participants in sexual selection. We also highlight that inadequate data reporting in the literature prevented us from extracting effect sizes from many studies that had presumably collected the relevant data.
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Affiliation(s)
- Renato C Macedo-Rego
- Programa de Pós-graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, no. 321, São Paulo, SP 05508-090, Brazil
- Division of Ecology & Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, 10 Marais Street, Stellenbosch, 7600, South Africa
| | - Eduardo S A Santos
- Programa de Pós-graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, no. 321, São Paulo, SP 05508-090, Brazil
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2
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Pollo P, Lagisz M, Yang Y, Culina A, Nakagawa S. Synthesis of sexual selection: a systematic map of meta-analyses with bibliometric analysis. Biol Rev Camb Philos Soc 2024. [PMID: 38982618 DOI: 10.1111/brv.13117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 06/16/2024] [Accepted: 06/19/2024] [Indexed: 07/11/2024]
Abstract
Sexual selection has been a popular subject within evolutionary biology because of its central role in explaining odd and counterintuitive traits observed in nature. Consequently, the literature associated with this field of study became vast. Meta-analytical studies attempting to draw inferences from this literature have now accumulated, varying in scope and quality, thus calling for a synthesis of these syntheses. We conducted a systematic literature search to create a systematic map with a report appraisal of meta-analyses on topics associated with sexual selection, aiming to identify the conceptual and methodological gaps in this secondary literature. We also conducted bibliometric analyses to explore whether these gaps are associated with the gender and origin of the authors of these meta-analyses. We included 152 meta-analytical studies in our systematic map. We found that most meta-analyses focused on males and on certain animal groups (e.g. birds), indicating severe sex and taxonomic biases. The topics in these studies varied greatly, from proximate (e.g. relationship of ornaments with other traits) to ultimate questions (e.g. formal estimates of sexual selection strength), although the former were more common. We also observed several common methodological issues in these studies, such as lack of detailed information regarding searches, screening, and analyses, which ultimately impairs the reliability of many of these meta-analyses. In addition, most of the meta-analyses' authors were men affiliated to institutions from developed countries, pointing to both gender and geographical authorship biases. Most importantly, we found that certain authorship aspects were associated with conceptual and methodological issues in meta-analytical studies. Many of our findings might simply reflect patterns in the current state of the primary literature and academia, suggesting that our study can serve as an indicator of issues within the field of sexual selection at large. Based on our findings, we provide both conceptual and analytical recommendations to improve future studies in the field of sexual selection.
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Affiliation(s)
- Pietro Pollo
- Evolution & Ecology Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Gate 9 High St., Kensington, Sydney, NSW, 2052, Australia
| | - Malgorzata Lagisz
- Evolution & Ecology Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Gate 9 High St., Kensington, Sydney, NSW, 2052, Australia
| | - Yefeng Yang
- Evolution & Ecology Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Gate 9 High St., Kensington, Sydney, NSW, 2052, Australia
| | - Antica Culina
- Ruđer Bošković Institute, Bijenička Cesta 54, Zagreb, 10000, Croatia
| | - Shinichi Nakagawa
- Evolution & Ecology Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Gate 9 High St., Kensington, Sydney, NSW, 2052, Australia
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3
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Driscoll RMH, Beaudry FEG, Cosgrove EJ, Bowman R, Fitzpatrick JW, Schoech SJ, Chen N. Allele frequency dynamics under sex-biased demography and sex-specific inheritance in a pedigreed jay population. Genetics 2024; 227:iyae075. [PMID: 38722645 PMCID: PMC11228872 DOI: 10.1093/genetics/iyae075] [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: 02/20/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 06/12/2024] Open
Abstract
Sex-biased demography, including sex-biased survival or migration, can alter allele frequency changes across the genome. In particular, we can expect different patterns of genetic variation on autosomes and sex chromosomes due to sex-specific differences in life histories, as well as differences in effective population size, transmission modes, and the strength and mode of selection. Here, we demonstrate the role that sex differences in life history played in shaping short-term evolutionary dynamics across the genome. We used a 25-year pedigree and genomic dataset from a long-studied population of Florida Scrub-Jays (Aphelocoma coerulescens) to directly characterize the relative roles of sex-biased demography and inheritance in shaping genome-wide allele frequency trajectories. We used gene dropping simulations to estimate individual genetic contributions to future generations and to model drift and immigration on the known pedigree. We quantified differential expected genetic contributions of males and females over time, showing the impact of sex-biased dispersal in a monogamous system. Due to female-biased dispersal, more autosomal variation is introduced by female immigrants. However, due to male-biased transmission, more Z variation is introduced by male immigrants. Finally, we partitioned the proportion of variance in allele frequency change through time due to male and female contributions. Overall, most allele frequency change is due to variance in survival and births. Males and females make similar contributions to autosomal allele frequency change, but males make higher contributions to allele frequency change on the Z chromosome. Our work shows the importance of understanding sex-specific demographic processes in characterizing genome-wide allele frequency change in wild populations.
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Affiliation(s)
- Rose M H Driscoll
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Felix E G Beaudry
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Elissa J Cosgrove
- Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY 14850, USA
| | - Reed Bowman
- Avian Ecology Program, Archbold Biological Station, Venus, FL 33960, USA
| | | | - Stephan J Schoech
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Nancy Chen
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
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4
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Fresneau N, Pipoly I, Gigler D, Kosztolányi A, Székely T, Liker A. The evolution of sex roles: The importance of ecology and social environment. Proc Natl Acad Sci U S A 2024; 121:e2321294121. [PMID: 38771872 PMCID: PMC11145285 DOI: 10.1073/pnas.2321294121] [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: 12/04/2023] [Accepted: 03/27/2024] [Indexed: 05/23/2024] Open
Abstract
Males and females often have different roles in reproduction, although the origin of these differences has remained controversial. Explaining the enigmatic reversed sex roles where males sacrifice their mating potential and provide full parental care is a particularly long-standing challenge in evolutionary biology. While most studies focused on ecological factors as the drivers of sex roles, recent research highlights the significance of social factors such as the adult sex ratio. To disentangle these propositions, here, we investigate the additive and interactive effects of several ecological and social factors on sex role variation using shorebirds (sandpipers, plovers, and allies) as model organisms that provide the full spectrum of sex role variation including some of the best-known examples of sex-role reversal. Our results consistently show that social factors play a prominent role in driving sex roles. Importantly, we show that reversed sex roles are associated with both male-skewed adult sex ratios and high breeding densities. Furthermore, phylogenetic path analyses provide general support for sex ratios driving sex role variations rather than being a consequence of sex roles. Together, these important results open future research directions by showing that different mating opportunities of males and females play a major role in generating the evolutionary diversity of sex roles, mating system, and parental care.
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Affiliation(s)
- Nolwenn Fresneau
- Evolutionary Ecology Research Group, Hungarian Research Network-University of Pannonia, Veszprém8200, Hungary
- Behavioural Ecology Research Group, Center for Natural Sciences, University of Pannonia, Veszprém8200, Hungary
| | - Ivett Pipoly
- Evolutionary Ecology Research Group, Hungarian Research Network-University of Pannonia, Veszprém8200, Hungary
- Behavioural Ecology Research Group, Center for Natural Sciences, University of Pannonia, Veszprém8200, Hungary
| | - Dóra Gigler
- World Wide Fund (WWF) for Nature Hungary Foundation, Budapest1141, Hungary
| | - András Kosztolányi
- Department of Zoology, University of Veterinary Medicine, Budapest1077, Hungary
| | - Tamás Székely
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Claverton Down, BathBA2 7AZ, United Kingdom
- Reproductive Strategies Research Group, Department of Evolutionary Zoology, Hungarian Research Network - University of Debrecen, Debrecen4032, Hungary
- Debrecen Biodiversity Centre, University of Debrecen, Debrecen4032, Hungary
| | - András Liker
- Evolutionary Ecology Research Group, Hungarian Research Network-University of Pannonia, Veszprém8200, Hungary
- Behavioural Ecology Research Group, Center for Natural Sciences, University of Pannonia, Veszprém8200, Hungary
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5
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Premate E, Fišer Ž, Biró A, Copilaş-Ciocianu D, Fromhage L, Jennions M, Borko Š, Herczeg G, Balázs G, Kralj-Fišer S, Fišer C. Sexual dimorphism in subterranean amphipod crustaceans covaries with subterranean habitat type. J Evol Biol 2024; 37:487-500. [PMID: 38483086 DOI: 10.1093/jeb/voae032] [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: 05/02/2023] [Revised: 01/19/2024] [Accepted: 03/12/2024] [Indexed: 05/07/2024]
Abstract
Sexual dimorphism can evolve in response to sex-specific selection pressures that vary across habitats. We studied sexual differences in subterranean amphipods Niphargus living in shallow subterranean habitats (close to the surface), cave streams (intermediate), and cave lakes (deepest and most isolated). These three habitats differ because at greater depths there is lower food availability, reduced predation, and weaker seasonality. Additionally, species near the surface have a near-even adult sex ratio (ASR), whereas species from cave lakes have a female-biased ASR. We hypothesized (a) a decrease in sexual dimorphism from shallow subterranean habitats to cave lake species because of weaker sexual selection derived from changes in the ASR and (b) an increase in female body size in cave lakes because of stronger fecundity selection on account of oligotrophy, reduced predation, and weaker seasonality. We measured body size and two sexually dimorphic abdominal appendages for all 31 species and several behaviours related to male competition (activity, risk-taking, exploration) for 12 species. Species with an equal ASR that live close to the surface exhibited sexual dimorphism in all three morphological traits, but not in behaviour. The body size of females increased from the surface to cave lakes, but no such trend was observed in males. In cave lake species, males and females differed neither morphologically nor behaviourally. Our results are consistent with the possibility that sexual and fecundity selection covary across the three habitats, which indirectly and directly, respectively, shape the degree of sexual dimorphism in Niphargus species.
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Affiliation(s)
- Ester Premate
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Žiga Fišer
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Anna Biró
- Doctoral School of Biology, Institute of Biology, ELTE-Eötvös Loránd University, Budapest, Hungary
- ELKH-ELTE-MTM Integrative Ecology Research Group, Budapest, Hungary
- Department of Systematic Zoology and Ecology, Institute of Biology, ELTE-Eötvös Loránd University, Budapest, Hungary
| | - Denis Copilaş-Ciocianu
- Laboratory of Evolutionary Ecology of Hydrobionts, Nature Research Centre, Vilnius, Lithuania
| | - Lutz Fromhage
- Department of Biological and Environmental Science, University of Jyvaskyla, Jyväskylä, Finland
| | - Michael Jennions
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Acton, Canberra, ACT, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, Stellenbosch, South Africa
| | - Špela Borko
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Gábor Herczeg
- ELKH-ELTE-MTM Integrative Ecology Research Group, Budapest, Hungary
- Department of Systematic Zoology and Ecology, Institute of Biology, ELTE-Eötvös Loránd University, Budapest, Hungary
| | - Gergely Balázs
- ELKH-ELTE-MTM Integrative Ecology Research Group, Budapest, Hungary
- Department of Systematic Zoology and Ecology, Institute of Biology, ELTE-Eötvös Loránd University, Budapest, Hungary
| | | | - Cene Fišer
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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6
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Weiss E. No Bones About It: Sex Is Binary. ARCHIVES OF SEXUAL BEHAVIOR 2024; 53:1595-1608. [PMID: 38565789 DOI: 10.1007/s10508-024-02851-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/02/2024] [Accepted: 03/04/2024] [Indexed: 04/04/2024]
Abstract
Anthropologists have led the way in formulating techniques that reveal skeletal differences between males and females. Understanding of physical differences in the pelvis related to childbirth, hormonal impacts on bones, and extensive comparative studies have provided anthropologists with an array of traits and measurements that help them estimate sex using just bones. Forensic anthropologists and bioarcheologists are improving their ability to differentiate males and females by increasing research on a variety of postcranial bones and through the use of molecular data, especially new methods called proteomics, to identify sex in prepubescent juveniles. As remains from more cultures and time periods are studied, sex identification will continue to improve, because skeletal sex differences are in large part biologically determined. Yet, anthropologists have also been at the forefront of arguing that sex lies on a spectrum. Anthropologists who view sex as on a spectrum may deter sex identification progress; from their perspective, an individual of an undetermined sex may just be a nonbinary individual. Anthropologists who consider sex is on a spectrum are coming to this conclusion in part because they are looking for anatomical ideals, mistaking pathology for variation, and confusing independent variables with dependent variables. Nonetheless, anthropologists need to continue to improve sex identification techniques to reconstruct the past accurately, which may reveal less strict sex roles than previously presumed and help with the identification of crime victims. Forensic anthropologists should also increase their efforts to identify whether individuals have undergone medical procedures intended to change one's gender due to the current rise in transitioning individuals.
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Affiliation(s)
- Elizabeth Weiss
- Department of Anthropology, San José State University, One Washington Square, San José, CA, 95192-0113, USA.
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7
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D'Amelio PB, Covas R, Ferreira AC, Fortuna R, Silva LR, Theron F, Rybak F, Doutrelant C. Benefits of Pair-Bond Duration on Reproduction in a Lifelong Monogamous Cooperative Passerine. Am Nat 2024; 203:576-589. [PMID: 38635359 DOI: 10.1086/729436] [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: 04/20/2024]
Abstract
AbstractLong-term social and genetic monogamy is rare in animals except birds, but even in birds it is infrequent and poorly understood. We investigated possible advantages of monogamy in a colonial, facultative cooperatively breeding bird from an arid, unpredictable environment, the sociable weaver (Philetairus socius). We documented divorce and extrapair paternity of 703 pairs over 10 years and separated effects of pair duration from breeding experience by analyzing longitudinal and cross-sectional datasets. Parts of the colonies were protected from nest predation, thereby limiting its stochastic and thus confounding effect on fitness measures. We found that 6.4% of sociable weaver pairs divorced and 2.2% of young were extrapair. Longer pair-bonds were associated with more clutches and fledglings per season and with reproducing earlier and later in the season, when snake predation is lower, but not with increased egg or fledgling mass or with nestling survival. Finally, the number of helpers at the nest increased with pair-bond duration. Results were similar for protected and unprotected nests. We suggest that long-term monogamy is associated with a better capacity for exploiting a temporally unpredictable environment and helps to form larger groups. These results can contribute to our understanding of why long-term monogamy is frequently associated with unpredictable environments and cooperation.
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8
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Mouginot M, Wilson ML, Desai N, Surbeck M. Differences in expression of male aggression between wild bonobos and chimpanzees. Curr Biol 2024; 34:1780-1785.e4. [PMID: 38614078 PMCID: PMC11167569 DOI: 10.1016/j.cub.2024.02.071] [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: 06/21/2023] [Revised: 01/22/2024] [Accepted: 02/28/2024] [Indexed: 04/15/2024]
Abstract
Researchers investigating the evolution of human aggression look to our closest living relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes), as valuable sources of comparative data.1,2 Males in the two species exhibit contrasting patterns: male chimpanzees sexually coerce females3,4,5,6,7,8 and sometimes kill conspecifics,9,10,11,12 whereas male bonobos exhibit less sexual coercion13,14 and no reported killing.13 Among the various attempts to explain these species differences, the self-domestication hypothesis proposes negative fitness consequences of male aggression in bonobos.2,15,16 Nonetheless, the extent to which these species differ in overall rates of aggression remains unclear due to insufficiently comparable observation methods.17,18,19,20,21,22,23 We used 14 community-years of focal follow data-the gold standard for observational studies24-to compare rates of male aggression in 3 bonobo communities at the Kokolopori Bonobo Reserve, Democratic Republic of Congo, and 2 chimpanzee communities at Gombe National Park, Tanzania. As expected, given that females commonly outrank males, we found that bonobos exhibited lower rates of male-female aggression and higher rates of female-male aggression than chimpanzees. Surprisingly, we found higher rates of male-male aggression among bonobos than chimpanzees even when limiting analyses to contact aggression. In both species, more aggressive males obtained higher mating success. Although our findings indicate that the frequency of male-male aggression does not parallel species difference in its intensity, they support the view that contrary to male chimpanzees, whose reproductive success depends on strong coalitions, male bonobos have more individualistic reproductive strategies.25.
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Affiliation(s)
- Maud Mouginot
- Institute for Advanced Study in Toulouse (IAST), Toulouse School of Economics, Université Toulouse Capitole, 31000 Toulouse, France; Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Michael L Wilson
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN 55108, USA; Institute on the Environment, University of Minnesota, Saint Paul, MN 55108, USA
| | - Nisarg Desai
- Emory National Primate Research Center, Emory University, Atlanta, GA 30329, USA
| | - Martin Surbeck
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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9
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Pappert FA, Dubin A, Torres GG, Roth O. Navigating sex and sex roles: deciphering sex-biased gene expression in a species with sex-role reversal ( Syngnathus typhle). ROYAL SOCIETY OPEN SCIENCE 2024; 11:rsos.231620. [PMID: 38577217 PMCID: PMC10987989 DOI: 10.1098/rsos.231620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/02/2024] [Accepted: 03/11/2024] [Indexed: 04/06/2024]
Abstract
Sexual dimorphism, the divergence in morphological traits between males and females of the same species, is often accompanied by sex-biased gene expression. However, the majority of research has focused on species with conventional sex roles, where females have the highest energy burden with both egg production and parental care, neglecting the diversity of reproductive roles found in nature. We investigated sex-biased gene expression in Syngnathus typhle, a sex-role reversed species with male pregnancy, allowing us to separate two female traits: egg production and parental care. Using RNA sequencing, we examined gene expression across organs (brain, head kidney and gonads) at various life stages, encompassing differences in age, sex and reproductive status. While some gene groups were more strongly associated with sex roles, such as stress resistance and immune defence, others were driven by biological sex, such as energy and lipid storage regulation in an organ- and age-specific manner. By investigating how genes regulate and are regulated by changing reproductive roles and resource allocation in a model system with an unconventional life-history strategy, we aim to better understand the importance of sex and sex role in regulating gene expression patterns, broadening the scope of this discussion to encompass a wide range of organisms.
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Affiliation(s)
- Freya A. Pappert
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
- Evolutionary Ecology of Marine Fishes, Helmholtz-Centre for Ocean Research Kiel (GEOMAR), Kiel24105, Germany
| | - Arseny Dubin
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
| | - Guillermo G. Torres
- Institute of Clinical Molecular Biology (IKMB), University Hospital Schleswig-Holstein, Kiel University, Kiel24105, Germany
| | - Olivia Roth
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
- Evolutionary Ecology of Marine Fishes, Helmholtz-Centre for Ocean Research Kiel (GEOMAR), Kiel24105, Germany
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10
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Liao A, Cavigliasso F, Savary L, Kawecki TJ. Effects of an entomopathogenic fungus on the reproductive potential of Drosophila males. Ecol Evol 2024; 14:e11242. [PMID: 38590549 PMCID: PMC10999951 DOI: 10.1002/ece3.11242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/20/2024] [Accepted: 03/25/2024] [Indexed: 04/10/2024] Open
Abstract
While mortality is often the primary focus of pathogen virulence, non-lethal consequences, particularly for male reproductive fitness, are less understood; however, they are essential for understanding how sexual selection contributes to promoting resistance. We investigated how the fungal pathogen Metarhizium brunneum affects mating ability, fertility, and seminal fluid protein (SFP) expression of male Drosophila melanogaster paired with highly receptive virgin females in non-competitive settings. Depending on sex and dose, there was a 3-6-day incubation period after infection, followed by an abrupt onset of mortality. Meanwhile, the immune response was strongly induced already 38 h after infection and continued to increase as infection progressed. Latency to mate somewhat increased during the incubation period compared to sham-treated males, but even on Day 5 post infection >90% of infected males mated within 2 h. During the incubation period, M. brunneum infection reduced male reproductive potential (the number of offspring sired without mate limitation) by 11%, with no clear increase over time. Approaching the end of the incubation period, infected males had lower ability to convert number of mating opportunities into number of offspring. After repeated mating, infected males had lower SFP expression than sham controls, more so in males that mated with few mates 24 h earlier. Overall, despite strong activation of the immune response, males' mating ability and fertility remained surprisingly little affected by the fungal infection, even shortly before the onset of mortality. This suggests that the selection for resistance acts mainly through mortality, and the scope for fertility selection to enhance resistance in non-competing settings is rather limited.
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Affiliation(s)
- Aijuan Liao
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Fanny Cavigliasso
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Loriane Savary
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Tadeusz J. Kawecki
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
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11
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Takayanagi JFGB, Siqueira JDO, Silveira PSP, Valentova JV. What Do Different People Look for in a Partner? Effects of Sex, Sexual Orientation, and Mating Strategies on Partner Preferences. ARCHIVES OF SEXUAL BEHAVIOR 2024; 53:981-1000. [PMID: 38413532 DOI: 10.1007/s10508-023-02767-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 11/17/2023] [Accepted: 11/27/2023] [Indexed: 02/29/2024]
Abstract
Partner preferences are an important differential in relationship formation and evolutionary fitness, and vary according to individual, ecological, and social factors. In this study, we evaluated the variation in preference for intelligence, kindness, physical attractiveness, health, and socioeconomic level among individuals of different sexes and sexual orientations in a Brazilian sample. We analyzed the preference scores of 778 heterosexual, bisexual, and homosexual men and women in three budgeted mate design tasks (low vs. medium vs. high budget) and their association with sociosexuality, attachment styles, homogamy, and willingness to engage in short- and long-term relationships. Results indicated a global trait preference order, with intelligence ranking first, followed by kindness, physical attractiveness, health, and lastly by socioeconomic status. Typical sex differences were observed mostly within the heterosexual group, and specific combinations of sex and sexual orientation were linked to variation in preference for physical attractiveness, kindness, and socioeconomic status. We also found unique associations of the other variables with partner preferences and with willingness to engage in short- or long-term relationships. By exploring the partner preferences of non-heterosexual individuals from a Latin American country, an underrepresented group in evolutionary psychology research, our results help understand the universal and specific factors that guide partner preferences and human sexual behavior.
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Affiliation(s)
- Joao Francisco Goes Braga Takayanagi
- Department of Experimental Psychology, Institute of Psychology, University of Sao Paulo, Professor Mello Moraes Avenue 1721, Butanta, São Paulo, SP, 05508-030, Brazil.
| | - Jose de Oliveira Siqueira
- Department of Legal Medicine, Bioethics, Occupational Medicine and Physical Medicine and Rehabilitation, Medical School, University of Sao Paulo, São Paulo, SP, Brazil
| | - Paulo Sergio Panse Silveira
- Department of Legal Medicine, Bioethics, Occupational Medicine and Physical Medicine and Rehabilitation, Medical School, University of Sao Paulo, São Paulo, SP, Brazil
- Department of Pathology (LIM01-HCFMUSP), Medical School, University of Sao Paulo, São Paulo, SP, Brazil
| | - Jaroslava Varella Valentova
- Department of Experimental Psychology, Institute of Psychology, University of Sao Paulo, Professor Mello Moraes Avenue 1721, Butanta, São Paulo, SP, 05508-030, Brazil
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12
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Xu L, Ren Y, Wu J, Cui T, Dong R, Huang C, Feng Z, Zhang T, Yang P, Yuan J, Xu X, Liu J, Wang J, Chen W, Mi D, Irwin DM, Yan Y, Xu L, Yu X, Li G. Evolution and expression patterns of the neo-sex chromosomes of the crested ibis. Nat Commun 2024; 15:1670. [PMID: 38395916 PMCID: PMC10891136 DOI: 10.1038/s41467-024-46052-x] [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: 06/21/2023] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Bird sex chromosomes play a unique role in sex-determination, and affect the sexual morphology and behavior of bird species. Core waterbirds, a major clade of birds, share the common characteristics of being sexually monomorphic and having lower levels of inter-sexual conflict, yet their sex chromosome evolution remains poorly understood. Here, by we analyse of a chromosome-level assembly of a female crested ibis (Nipponia nippon), a typical core waterbird. We identify neo-sex chromosomes resulting from fusion of microchromosomes with ancient sex chromosomes. These fusion events likely occurred following the divergence of Threskiornithidae and Ardeidae. The neo-W chromosome of the crested ibis exhibits the characteristics of slow degradation, which is reflected in its retention of abundant gametologous genes. Neo-W chromosome genes display an apparent ovary-biased gene expression, which is largely driven by genes that are retained on the crested ibis W chromosome but lost in other bird species. These results provide new insights into the evolutionary history and expression patterns for the sex chromosomes of bird species.
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Affiliation(s)
- Lulu Xu
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Yandong Ren
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Jiahong Wu
- MOE Key Laboratory of Freshwater Fish Reproduction and Development, School of Life Sciences, Southwest University, Chongqing, China
| | - Tingting Cui
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Rong Dong
- Research Center for Qinling Giant Panda, Shaanxi Academy of Forestry, Xi'an, China
| | - Chen Huang
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Zhe Feng
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Tianmin Zhang
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Peng Yang
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Jiaqing Yuan
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Xiao Xu
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Jiao Liu
- MOE Key Laboratory of Freshwater Fish Reproduction and Development, School of Life Sciences, Southwest University, Chongqing, China
| | - Jinhong Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Wu Chen
- Guangzhou Wildlife Research Center, Guangzhou Zoo, Guangzhou, China
| | - Da Mi
- Xi'an Haorui Genomics Technology Co., LTD, Xi'an, China
| | - David M Irwin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Yaping Yan
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Luohao Xu
- MOE Key Laboratory of Freshwater Fish Reproduction and Development, School of Life Sciences, Southwest University, Chongqing, China.
| | - Xiaoping Yu
- College of Life Sciences, Shaanxi Normal University, Xi'an, China.
| | - Gang Li
- College of Life Sciences, Shaanxi Normal University, Xi'an, China.
- Guangzhou Wildlife Research Center, Guangzhou Zoo, Guangzhou, China.
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13
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Gómez-Llano M, Faria GS, García-Roa R, Noble DWA, Carazo P. Male harm suppresses female fitness, affecting the dynamics of adaptation and evolutionary rescue. Evol Lett 2024; 8:149-160. [PMID: 38370549 PMCID: PMC10871930 DOI: 10.1093/evlett/qrac002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/22/2023] [Accepted: 12/19/2022] [Indexed: 02/20/2024] Open
Abstract
One of the most pressing questions we face as biologists is to understand how climate change will affect the evolutionary dynamics of natural populations and how these dynamics will in turn affect population recovery. Increasing evidence shows that sexual selection favors population viability and local adaptation. However, sexual selection can also foster sexual conflict and drive the evolution of male harm to females. Male harm is extraordinarily widespread and has the potential to suppress female fitness and compromise population growth, yet we currently ignore its net effects across taxa or its influence on local adaptation and evolutionary rescue. We conducted a comparative meta-analysis to quantify the impact of male harm on female fitness and found an overall negative effect of male harm on female fitness. Negative effects seem to depend on proxies of sexual selection, increasing inversely to the female relative size and in species with strong sperm competition. We then developed theoretical models to explore how male harm affects adaptation and evolutionary rescue. We show that, when sexual conflict depends on local adaptation, population decline is reduced, but at the cost of slowing down genetic adaptation. This trade-off suggests that eco-evolutionary feedback on sexual conflict can act like a double-edged sword, reducing extinction risk by buffering the demographic costs of climate change, but delaying genetic adaptation. However, variation in the mating system and male harm type can mitigate this trade-off. Our work shows that male harm has widespread negative effects on female fitness and productivity, identifies potential mechanistic factors underlying variability in such costs across taxa, and underscores how acknowledging the condition-dependence of male harm may be important to understand the demographic and evolutionary processes that impact how species adapt to environmental change.
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Affiliation(s)
- Miguel Gómez-Llano
- Department of Biological Sciences, University of Arkansas, Fayetteville, United States
- Department of Environmental and Life Sciences, Karlstad University, Karlstad, Sweden
| | - Gonçalo S Faria
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Roberto García-Roa
- Ethology lab, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
- Department of Biology, Lund University, Lund, Sweden
| | - Daniel W A Noble
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
| | - Pau Carazo
- Ethology lab, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
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14
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Siljestam M, Martinossi-Allibert I. Anisogamy Does Not Always Promote the Evolution of Mating Competition Traits in Males. Am Nat 2024; 203:230-253. [PMID: 38306281 DOI: 10.1086/727968] [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: 02/04/2024]
Abstract
AbstractAnisogamy has evolved in most sexually reproducing multicellular organisms allowing the definition of male and female sexes, producing small and large gametes. Anisogamy, as the initial sexual dimorphism, is a good starting point to understand the evolution of further sexual dimorphisms. For instance, it is generally accepted that anisogamy sets the stage for more intense mating competition in males than in females. We argue that this idea stems from a restrictive assumption on the conditions under which anisogamy evolved in the first place: the absence of sperm limitation (assuming that all female gametes are fertilized). Here, we relax this assumption and present a model that considers the coevolution of gamete size with a mating competition trait, starting in a population without dimorphism. We vary gamete density to produce different scenarios of gamete limitation. We show that while at high gamete density the evolution of anisogamy always results in male investment in competition, gamete limitation at intermediate gamete densities allows for either females or males to invest more into mating competition. Our results thus suggest that anisogamy does not always promote mating competition among males. The conditions under which anisogamy evolves matter, as does the competition trait.
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15
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Crino OL, Head ML, Jennions MD, Noble DWA. Mitochondrial function and sexual selection: can physiology resolve the 'lek paradox'? J Exp Biol 2024; 227:jeb245569. [PMID: 38206324 DOI: 10.1242/jeb.245569] [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] [Indexed: 01/12/2024]
Abstract
Across many taxa, males use elaborate ornaments or complex displays to attract potential mates. Such sexually selected traits are thought to signal important aspects of male 'quality'. Female mating preferences based on sexual traits are thought to have evolved because choosy females gain direct benefits that enhance their lifetime reproductive success (e.g. greater access to food) and/or indirect benefits because high-quality males contribute genes that increase offspring fitness. However, it is difficult to explain the persistence of female preferences when males only provide genetic benefits, because female preferences should erode the heritable genetic variation in fitness that sexually selected traits signal. This 'paradox of the lek' has puzzled evolutionary biologists for decades, and inspired many hypotheses to explain how heritable variation in sexually selected traits is maintained. Here, we discuss how factors that affect mitochondrial function can maintain variation in sexually selected traits despite strong female preferences. We discuss how mitochondrial function can influence the expression of sexually selected traits, and we describe empirical studies that link the expression of sexually selected traits to mitochondrial function. We explain how mothers can affect mitochondrial function in their offspring by (a) influencing their developmental environment through maternal effects and (b) choosing a mate to increase the compatibility of mitochondrial and nuclear genes (i.e. the 'mitonuclear compatibility model of sexual selection'). Finally, we discuss how incorporating mitochondrial function into models of sexual selection might help to resolve the paradox of the lek, and we suggest avenues for future research.
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Affiliation(s)
- Ondi L Crino
- School of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
| | - Megan L Head
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
| | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, 10 Marais Street, Stellenbosch 7600, South Africa
| | - Daniel W A Noble
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
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16
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Chang CC, Moiron M, Sánchez-Tójar A, Niemelä PT, Laskowski KL. What is the meta-analytic evidence for life-history trade-offs at the genetic level? Ecol Lett 2024; 27:e14354. [PMID: 38115163 DOI: 10.1111/ele.14354] [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: 06/27/2023] [Revised: 09/21/2023] [Accepted: 11/21/2023] [Indexed: 12/21/2023]
Abstract
Understanding the evolutionary mechanisms underlying the maintenance of individual differences in behavior and physiology is a fundamental goal in ecology and evolution. The pace-of-life syndrome hypothesis is often invoked to explain the maintenance of such within-population variation. This hypothesis predicts that behavioral traits are part of a suite of correlated traits that collectively determine an individual's propensity to prioritize reproduction or survival. A key assumption of this hypothesis is that these traits are underpinned by genetic trade-offs among life-history traits: genetic variants that increase fertility, reproduction and growth might also reduce lifespan. We performed a systematic literature review and meta-analysis to summarize the evidence for the existence of genetic trade-offs between five key life-history traits: survival, growth rate, body size, maturation rate, and fertility. Counter to our predictions, we found an overall positive genetic correlation between survival and other life-history traits and no evidence for any genetic correlations between the non-survival life-history traits. This finding was generally consistent across pairs of life-history traits, sexes, life stages, lab vs. field studies, and narrow- vs. broad-sense correlation estimates. Our study highlights that genetic trade-offs may not be as common, or at least not as easily quantifiable, in animals as often assumed.
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Affiliation(s)
- Chia-Chen Chang
- Department of Evolution and Ecology, University of California, Davis, California, USA
| | - Maria Moiron
- Institute of Avian Research, Wilhelmshaven, Germany
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| | | | - Petri T Niemelä
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Kate L Laskowski
- Department of Evolution and Ecology, University of California, Davis, California, USA
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17
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Eberhart-Hertel LJ, Rodrigues LF, Krietsch J, Hertel AG, Cruz-López M, Vázquez-Rojas KA, González-Medina E, Schroeder J, Küpper C. Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers. Evolution 2023; 77:2590-2605. [PMID: 37757813 DOI: 10.1093/evolut/qpad168] [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: 08/10/2021] [Revised: 08/15/2023] [Accepted: 09/25/2023] [Indexed: 09/29/2023]
Abstract
Gamete size variation between the sexes is central to the concept of sex roles, however, to what extent gamete size variation within the sexes relates to sex role variation remains unclear. Comparative and theoretical studies suggest that, when clutch size is invariable, polyandry is linked to a reduction of egg size, while increased female-female competition for mates favors early breeding when females cannot monopolize multiple males. To understand whether and how breeding phenology, egg size, and mating behavior are related at the individual level, we studied the reproductive histories of 424 snowy plover females observed in the wild over a 15-year period. Egg size, but not polyandry, were highly repeatable for individual females. Consistent with theoretical predictions, we found that polyandrous females were the earliest breeders and that early clutches contained smaller eggs than clutches initiated later. Neither egg size nor mating behavior showed clear signs of an age-related deterioration, on the contrary, prior experience acquired either through age or local recruitment enabled females to nest early. Taken together, these results suggest that gamete size variation is not linked to mating behavior at the individual level, and, consequently, the adaptive potential of such variation appears to be limited.
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Affiliation(s)
- Luke J Eberhart-Hertel
- Department of Ornithology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
- Research Group Behavioural Genetics and Evolutionary Ecology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
| | - Lourenço Falcão Rodrigues
- Department of Ecology, Autonomous University of Madrid, Madrid, Spain
- Department of Life Sciences, Imperial College London, Silwood Park Campus, United Kingdom
| | - Johannes Krietsch
- Department of Ornithology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
| | - Anne G Hertel
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
| | - Medardo Cruz-López
- Institute of Ocean Sciences and Limnology, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
| | - Karina Alejandra Vázquez-Rojas
- Research Group Behavioural Genetics and Evolutionary Ecology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
| | - Erick González-Medina
- Conservation Biology Research Group, Department of Anatomy, Cell Biology and Zoology, University of Extremadura, Badajoz, Spain
| | - Julia Schroeder
- Department of Life Sciences, Imperial College London, Silwood Park Campus, United Kingdom
| | - Clemens Küpper
- Research Group Behavioural Genetics and Evolutionary Ecology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
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18
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Székely T. Evolution of reproductive strategies: sex roles, sex ratios and phylogenies. Biol Futur 2023; 74:351-357. [PMID: 37723361 DOI: 10.1007/s42977-023-00177-0] [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] [Received: 01/30/2023] [Accepted: 08/22/2023] [Indexed: 09/20/2023]
Abstract
Behavioural variations associated with breeding-termed reproductive strategies-are some of the striking behaviours that have occupied naturalists for 1000s of years. How an animal seeks, competes for and/or chooses a mate? Do they breed with a single partner, or do they change partners between breeding events? How and when do they look after their young? Behavioural biologists, ecologists and evolutionary biologists have investigated these questions using quantitative methods since 1970s. In Debrecen, with the support and mentoring of Prof Zoltán Varga, we are investigating the causes and implications of reproductive strategies since 1988. This article reviews some of the core ideas in reproductive strategies research and explains the influence of Prof Varga on the development of these ideas. My main thesis here is that both integrative thinking and adopting a multi-pronged research approach using an explicit phylogenetic framework-both of these have been spearheaded by Prof Varga throughout his lifetime-can reveal novel aspects of reproductive strategies. Importantly, some of these academic insights have direct implications for preserving species and their habitats in the wild, and thus benefit biodiversity conservation.
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Affiliation(s)
- Tamás Székely
- Milner Centre for Evolution, University of Bath, Bath, BA2 7AY, UK.
- ELKH - DE Reproductive strategies Research Group, Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem Tér 1, Debrecen, 4032, Hungary.
- Debrecen Biodiversity Centre, University of Debrecen, Debrecen, 4032, Hungary.
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19
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Davies N, Janicke T, Morrow EH. Evidence for stronger sexual selection in males than in females using an adapted method of Bateman's classic study of Drosophila melanogaster. Evolution 2023; 77:2420-2430. [PMID: 37624087 DOI: 10.1093/evolut/qpad151] [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] [Received: 03/15/2023] [Revised: 07/10/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Bateman's principles, originally a test of Darwin's theoretical ideas, have since become fundamental to sexual selection theory and vital to contextualizing the role of anisogamy in sex differences of precopulatory sexual selection. Despite this, Bateman's principles have received substantial criticism, and researchers have highlighted both statistical and methodological errors, suggesting that Bateman's original experiment contains too much sampling bias for there to be any evidence of sexual selection. This study uses Bateman's original method as a template, accounting for two fundamental flaws in his original experiments, (a) viability effects and (b) a lack of mating behavior observation. Experimental populations of Drosophila melanogaster consisted of wild-type focal individuals and nonfocal individuals established by backcrossing the brown eye (bw-) eye-color marker-thereby avoiding viability effects. Mating assays included direct observation of mating behavior and total number of offspring, to obtain measures of mating success, reproductive success, and standardized variance measures based on Bateman's principles. The results provide observational support for Bateman's principles, particularly that (a) males had significantly more variation in number of mates compared with females and (b) males had significantly more individual variation in total number of offspring. We also find a significantly steeper Bateman gradient for males compared to females, suggesting that sexual selection is operating more intensely in males. However, female remating was limited, providing the opportunity for future study to further explore female reproductive success in correlation with higher levels of remating.
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Affiliation(s)
- Natasha Davies
- School of Life Sciences, University of Sussex, Falmer, East Sussex, United Kingdom
| | - Tim Janicke
- Applied Zoology, Technical University Dresden, Dresden, Germany
- CEFE, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France
| | - Edward H Morrow
- School of Life Sciences, University of Sussex, Falmer, East Sussex, United Kingdom
- Department for Environmental and Life Sciences, Karlstad University, Karlstad, Sweden
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20
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Polverino G, Aich U, Brand JA, Bertram MG, Martin JM, Tan H, Soman VR, Mason RT, Wong BBM. Sex-specific effects of psychoactive pollution on behavioral individuality and plasticity in fish. Behav Ecol 2023; 34:969-978. [PMID: 37969553 PMCID: PMC10636733 DOI: 10.1093/beheco/arad065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 07/17/2023] [Accepted: 07/31/2023] [Indexed: 11/17/2023] Open
Abstract
The global rise of pharmaceutical contaminants in the aquatic environment poses a serious threat to ecological and evolutionary processes. Studies have traditionally focused on the collateral (average) effects of psychoactive pollutants on ecologically relevant behaviors of wildlife, often neglecting effects among and within individuals, and whether they differ between males and females. We tested whether psychoactive pollutants have sex-specific effects on behavioral individuality and plasticity in guppies (Poecilia reticulata), a freshwater species that inhabits contaminated waterways in the wild. Fish were exposed to fluoxetine (Prozac) for 2 years across multiple generations before their activity and stress-related behavior were repeatedly assayed. Using a Bayesian statistical approach that partitions the effects among and within individuals, we found that males-but not females-in fluoxetine-exposed populations differed less from each other in their behavior (lower behavioral individuality) than unexposed males. In sharp contrast, effects on behavioral plasticity were observed in females-but not in males-whereby exposure to even low levels of fluoxetine resulted in a substantial decrease (activity) and increase (freezing behavior) in the behavioral plasticity of females. Our evidence reveals that psychoactive pollution has sex-specific effects on the individual behavior of fish, suggesting that males and females might not be equally vulnerable to global pollutants.
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Affiliation(s)
- Giovanni Polverino
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
- Department of Ecological and Biological Sciences, University of Tuscia, L.go dell'Università snc, Viterbo, 01100, Italy
| | - Upama Aich
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Jack A Brand
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Michael G Bertram
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, SE-907 36, Umeå,Sweden
| | - Jake M Martin
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, SE-907 36, Umeå,Sweden
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18b114 18, Stockholm, Sweden
| | - Hung Tan
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Vrishin R Soman
- Department of Mechanical and Aerospace Engineering, New York University, 370 Jay Street, Brooklyn, 11201, NY, USA
| | - Rachel T Mason
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
- School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, 3125, Victoria, Australia
| | - Bob B M Wong
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
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21
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Wang D, Zhang W, Yang S, Richter XYL. Sex differences in avian parental care patterns vary across the breeding cycle. Nat Commun 2023; 14:6980. [PMID: 37914691 PMCID: PMC10620184 DOI: 10.1038/s41467-023-42767-5] [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: 11/04/2022] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Parental care in birds consists of elaborate forms across stages, including nest building, incubation, and offspring provision. Despite their evolutionary importance, knowledge gaps exist in the extent to which parents contribute disproportionately to these forms and factors that are associated with variations in care patterns between sexes. Here, we analyzed 1533 bird species and discovered remarkable variability in care patterns. We show that parental care should not be viewed as a unitary trait but rather as a set of integrated features that exhibit considerable temporal and sex-specific variation. Our analyses also reveal moderate consistency in care patterns between breeding stages, pointing towards shared intrinsic factors driving sex-specific care. Notably, we found that species experiencing strong sexual selection on males or species facing paternity uncertainty display a tendency towards female-biased care. This work advances our understanding of the temporal variations in sex-specific contributions to avian parental care and their potential evolutionary drivers.
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Affiliation(s)
- Daiping Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Wenyuan Zhang
- Edward Grey Institute, Department of Biology, University of Oxford, Oxford, OX1 3SZ, UK
- Department of Biology, Quebec Centre for Biodiversity Science, McGill University, Montreal, QC, H3A 1B1, Canada
| | - Shuai Yang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xiang-Yi Li Richter
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, CH-3012, Bern, Switzerland.
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22
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Araujo G, Moura RR. Beyond classical theories: An integrative mathematical model of mating dynamics and parental care. J Evol Biol 2023; 36:1411-1427. [PMID: 37691454 DOI: 10.1111/jeb.14210] [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] [Received: 04/24/2022] [Revised: 06/29/2023] [Accepted: 07/11/2023] [Indexed: 09/12/2023]
Abstract
Classical theories, such as Bateman's principle and Trivers' parental investment theory, attempted to explain the coevolution of sexual selection and parental care through simple verbal arguments. Since then, quantitative models have demonstrated that it is rarely that simple because many non-intuitive structures and non-linear relationships are actually at play. In this study, we propose a new standard for models of mating dynamics and parental care, emphasizing the clarity and use of mathematical and probabilistic arguments, the meaning of consistency conditions, and the key role of spatial densities and the law of mass action. We used adaptive dynamics to calculate the evolutionary trajectory of the total care duration. Our results clearly show how the outcomes of parental care evolution can be diverse, depending on the quantitative balance between a set of dynamical forces arising from relevant differences and conditions in the male and female populations. The intensity of sexual selection, synergy of care, care quality, and relative mortality rates during mating interactions and caring activities act as forces driving evolutionary transitions between uniparental and biparental care. Sexual selection reduces the care duration of the selected sex, uniparental care evolves in the sex that offers the higher care quality, higher mortality during mating interactions of one sex leads to more care by that sex, and higher mortality during caring activities of one sex favours the evolution of uniparental care in the other sex. Both synergy and higher overall mortality during mating interactions can stabilize biparental care when sexual selection reduces the care duration of the selected sex. We discuss how the interaction between these forces influences the evolution of care patterns, and how sex ratios can vary and be interpreted in these contexts. We also propose new directions for future developments of our integrative model, creating new comparable analyses that share the same underlying assumptions and dynamical frameworks.
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Affiliation(s)
- Gui Araujo
- Faculty of Science and Engineering, Department of Biosciences, Swansea University, Wales, UK
- Departamento de Ciâncias Agrárias e Naturais, Núcleo de Extensão e Pesquisa em Ecologia e Evolução (NEPEE), Universidade do Estado de Minas Gerais, Ituiutaba, Brazil
| | - Rafael Rios Moura
- Departamento de Ciâncias Agrárias e Naturais, Núcleo de Extensão e Pesquisa em Ecologia e Evolução (NEPEE), Universidade do Estado de Minas Gerais, Ituiutaba, Brazil
- Pós-graduação em Ecologia, Conservação e Biodiversidade, Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Brazil
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23
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de Vries C, Lehtonen J. Sex-specific assumptions and their importance in models of sexual selection. Trends Ecol Evol 2023; 38:927-935. [PMID: 37246084 DOI: 10.1016/j.tree.2023.04.013] [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] [Received: 10/15/2022] [Revised: 04/14/2023] [Accepted: 04/24/2023] [Indexed: 05/30/2023]
Abstract
Sexual selection is a field coloured by tension and contrasting views. One contested claim is the causal link from the definition of the sexes (anisogamy) to divergent selection on the sexes. Does theory truly engage with this claim? We survey the extent to which theory makes sex-specific assumptions and engages with anisogamy, and discuss these issues in a broader context. The majority of theory in sexual selection makes sex-specific assumptions and does not engage with the definition of the sexes. While this does not invalidate existing results, debates and criticisms regarding sexual selection force us to think deeper about its logical foundations. We discuss ways to strengthen the foundations of sexual selection theory by relaxing central assumptions.
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Affiliation(s)
- Charlotte de Vries
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä 40014, Finland; Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
| | - Jussi Lehtonen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä 40014, Finland.
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Lavaut E, Valero M, Mauger S, Guillemin ML, Destombe C, Dufay M. Sexual selection in seaweed? Testing Bateman's principles in the red alga Gracilaria gracilis. Proc Biol Sci 2023; 290:20231668. [PMID: 37700657 PMCID: PMC10498045 DOI: 10.1098/rspb.2023.1668] [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: 07/25/2023] [Accepted: 08/21/2023] [Indexed: 09/14/2023] Open
Abstract
In anisogamous species, sexual selection is expected to be stronger in males. Bateman's principles state that the variance in (i) reproductive and (ii) mating success is greater for males, and (iii) the relationship between reproductive success and mating success (the Bateman gradient) is also stronger for males than for females. Sexual selection, based on Bateman's principles, has been demonstrated in animals and some angiosperms, but never in a seaweed. Here we focus on the oogamous haploid-diploid rhodophyte Gracilaria gracilis in which previous studies have shown evidence for non-random mating, suggesting the existence of male-male competition and female choice. We estimated mating and reproductive success using paternity analyses in a natural population where up to 92% of fertilizations occurred between partners of that population. The results show that the variance in mating success is significantly greater in males than in females and that the Bateman gradient is positive only in males. Distance to female partners also explains a minor part of the variance in male mating success. Although there is no evidence for sexual dimorphism, our study supports the hypothesis that sexual selection occurs in G. gracilis, probably on male traits, even if we cannot observe, characterize or quantify them yet.
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Affiliation(s)
- E. Lavaut
- IRL EBEA 3614, Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, CS 90074, Place Georges Teissier, 29688 Roscoff cedex, France
| | - M. Valero
- IRL EBEA 3614, Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, CS 90074, Place Georges Teissier, 29688 Roscoff cedex, France
| | - S. Mauger
- IRL EBEA 3614, Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, CS 90074, Place Georges Teissier, 29688 Roscoff cedex, France
| | - M. L. Guillemin
- IRL EBEA 3614, Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, CS 90074, Place Georges Teissier, 29688 Roscoff cedex, France
- Núcleo Milenio MASH, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - C. Destombe
- IRL EBEA 3614, Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, CS 90074, Place Georges Teissier, 29688 Roscoff cedex, France
| | - M. Dufay
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
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25
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Anderson AP, Renn SCP. The Ancestral Modulation Hypothesis: Predicting Mechanistic Control of Sexually Heteromorphic Traits Using Evolutionary History. Am Nat 2023; 202:241-259. [PMID: 37606950 DOI: 10.1086/725438] [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: 08/23/2023]
Abstract
AbstractAcross the animal kingdom there are myriad forms within a sex across, and even within, species, rendering concepts of universal sex traits moot. The mechanisms that regulate the development of these trait differences are varied, although in vertebrates, common pathways involve gonadal steroid hormones. Gonadal steroids are often associated with heteromorphic trait development, where the steroid found at higher circulating levels is the one involved in trait development for that sex. Occasionally, there are situations in which a gonadal steroid associated with heteromorphic trait development in one sex is involved in heteromorphic or monomorphic trait development in another sex. We propose a verbal hypothesis, the ancestral modulation hypothesis (AMH), that uses the evolutionary history of the trait-particularly which sex ancestrally possessed higher trait values-to predict the regulatory pathway that governs trait expression. The AMH predicts that the genomic architecture appears first to resolve sexual conflict in an initially monomorphic trait. This architecture takes advantage of existing sex-biased signals, the gonadal steroid pathway, to generate trait heteromorphism. In cases where the other sex experiences evolutionary pressure for the new phenotype, that sex will co-opt the existing architecture by altering its signal to match that of the original high-trait-value sex. We describe the integrated levels needed to produce this pattern and what the expected outcomes will be given the evolutionary history of the trait. We present this framework as a testable hypothesis for the scientific community to investigate and to create further engagement and analysis of both ultimate and proximate approaches to sexual heteromorphism.
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26
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Tschol M, Reid JM, Bocedi G. Environmental variance in male mating success modulates the positive versus negative impacts of sexual selection on genetic load. J Evol Biol 2023; 36:1242-1254. [PMID: 37497848 DOI: 10.1111/jeb.14202] [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] [Received: 11/26/2022] [Revised: 06/13/2023] [Accepted: 06/19/2023] [Indexed: 07/28/2023]
Abstract
Sexual selection on males is predicted to increase population fitness, and delay population extinction, when mating success negatively covaries with genetic load across individuals. However, such benefits of sexual selection could be counteracted by simultaneous increases in genome-wide drift resulting from reduced effective population size caused by increased variance in fitness. Resulting fixation of deleterious mutations could be greatest in small populations, and when environmental variation in mating traits partially decouples sexual selection from underlying genetic variation. The net consequences of sexual selection for genetic load and population persistence are therefore likely to be context dependent, but such variation has not been examined. We use a genetically explicit individual-based model to show that weak sexual selection can increase population persistence time compared to random mating. However, for stronger sexual selection such positive effects can be overturned by the detrimental effects of increased genome-wide drift. Furthermore, the relative strengths of mutation-purging and drift critically depend on the environmental variance in the male mating trait. Specifically, increasing environmental variance caused stronger sexual selection to elevate deleterious mutation fixation rate and mean selection coefficient, driving rapid accumulation of drift load and decreasing population persistence times. These results highlight an intricate balance between conflicting positive and negative consequences of sexual selection on genetic load, even in the absence of sexually antagonistic selection. They imply that environmental variances in key mating traits, and intrinsic genetic drift, should be properly factored into future theoretical and empirical studies of the evolution of population fitness under sexual selection.
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Affiliation(s)
| | - Jane M Reid
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
- Centre for Biodiversity Dynamics, Institutt for Biologi, NTNU, Trondheim, Norway
| | - Greta Bocedi
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
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27
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Andersson L, Jalovaara M, Saarela J, Uggla C. A matter of time: Bateman's principles and mating success as count and duration across social strata in contemporary Finland. Proc Biol Sci 2023; 290:20231061. [PMID: 37434521 PMCID: PMC10336387 DOI: 10.1098/rspb.2023.1061] [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: 05/12/2023] [Accepted: 06/19/2023] [Indexed: 07/13/2023] Open
Abstract
Bateman's principles heavily influence the understanding of human reproductive behaviour. Yet, few rigorous studies on Bateman's principles in contemporary industrialized populations exist. Most studies use small samples, exclude non-marital unions, and disregard recent insights on within-population heterogeneity in mating strategies. We assess mating success and reproductive success using population-wide Finnish register data on marital and non-marital cohabitations and fertility. We examine variability across social strata in the Bateman principles and analyse the mate count, the cumulated duration with a mate, and the association with reproductive success. Results support Bateman's first and second principles. Regarding Bateman's third principle, the number of mates is more positively associated with reproductive success for men than women, but this association is driven by ever having a mate. Having more than one mate is on average associated with lower reproductive success. However, for men in the lowest income quartile, having more than one mate positively predicts reproductive success. Longer union duration is associated with higher reproductive success, and more so for men. We note that sex differences in the relationship between mating success and reproductive success differ by social strata, and argue that mate duration may be an important component of mating success alongside mate count.
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Affiliation(s)
- Linus Andersson
- Department of Social Research, University of Turku, Turku, Varsinais-Suomi, 20014 Finland
- The Swedish Institute for Social Research, Stockholm University, Stockholm, 10691, Sweden
| | - Marika Jalovaara
- Department of Social Research, University of Turku, Turku, Varsinais-Suomi, 20014 Finland
| | - Jan Saarela
- Åbo Akademi, Abo, Varsinais-Suomi, 20500 Finland
| | - Caroline Uggla
- Stockholm University Demography Unit (SUDA), Department of Sociology, Stockholm University, Stockholm, 106 91, Sweden
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28
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Ross CT, Hooper PL, Smith JE, Jaeggi AV, Smith EA, Gavrilets S, Zohora FT, Ziker J, Xygalatas D, Wroblewski EE, Wood B, Winterhalder B, Willführ KP, Willard AK, Walker K, von Rueden C, Voland E, Valeggia C, Vaitla B, Urlacher S, Towner M, Sum CY, Sugiyama LS, Strier KB, Starkweather K, Major-Smith D, Shenk M, Sear R, Seabright E, Schacht R, Scelza B, Scaggs S, Salerno J, Revilla-Minaya C, Redhead D, Pusey A, Purzycki BG, Power EA, Pisor A, Pettay J, Perry S, Page AE, Pacheco-Cobos L, Oths K, Oh SY, Nolin D, Nettle D, Moya C, Migliano AB, Mertens KJ, McNamara RA, McElreath R, Mattison S, Massengill E, Marlowe F, Madimenos F, Macfarlan S, Lummaa V, Lizarralde R, Liu R, Liebert MA, Lew-Levy S, Leslie P, Lanning J, Kramer K, Koster J, Kaplan HS, Jamsranjav B, Hurtado AM, Hill K, Hewlett B, Helle S, Headland T, Headland J, Gurven M, Grimalda G, Greaves R, Golden CD, Godoy I, Gibson M, Mouden CE, Dyble M, Draper P, Downey S, DeMarco AL, Davis HE, Crabtree S, Cortez C, Colleran H, Cohen E, Clark G, Clark J, Caudell MA, Carminito CE, Bunce J, Boyette A, Bowles S, Blumenfield T, Beheim B, Beckerman S, Atkinson Q, Apicella C, Alam N, Mulder MB. Reproductive inequality in humans and other mammals. Proc Natl Acad Sci U S A 2023; 120:e2220124120. [PMID: 37216525 PMCID: PMC10235947 DOI: 10.1073/pnas.2220124120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 04/16/2023] [Indexed: 05/24/2023] Open
Abstract
To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women's fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species-including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.
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Affiliation(s)
- Cody T. Ross
- Santa Fe Institute, Santa Fe, NM87501
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Paul L. Hooper
- Santa Fe Institute, Santa Fe, NM87501
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | | | - Adrian V. Jaeggi
- Institut für Anthropologie und Anthropologisches Museum, University of Zürich, Zürich8006, Switzerland
| | - Eric Alden Smith
- Department of Anthropology, University of Washington, Seattle, WA98195
| | - Sergey Gavrilets
- Departments of Ecology and Evolutionary Biology and Mathematics, University of Tennessee, Knoxville, TN37996
| | - Fatema tuz Zohora
- International Centre for Diarrheal Disease Research, Dhaka1000, Bangladesh
| | - John Ziker
- Department of Anthropology, Boise State University, Boise, ID83725
| | | | | | - Brian Wood
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Anthropology, University of California, Los Angeles, CA90095
| | | | - Kai P. Willführ
- Institute for Social Science, University of Oldenburg, Oldenburg26129, Germany
| | - Aiyana K. Willard
- Centre for Culture and Evolution, Brunel University, LondonUB8 3PH, United Kingdom
| | - Kara Walker
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC27695
| | | | - Eckart Voland
- Institute for Philosophy, Justus-Liebig University, Giessen35390, Germany
| | | | - Bapu Vaitla
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Samuel Urlacher
- Department of Anthropology, Baylor University, Waco, TX76706
- Canadian Institute for Advanced Research, Toronto, CAM5G 1M1
| | - Mary Towner
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK74078
| | - Chun-Yi Sum
- College of General Studies, Boston University, Boston, MA02215
| | | | - Karen B. Strier
- Department of Zoology, University of Wisconsin, Madison, WI53706
| | | | - Daniel Major-Smith
- Department of Anthropology and Archaeology, University of Bristol, BristolBS8 1QU, United Kingdom
| | - Mary Shenk
- Department of Anthropology, Pennsylvania State University, University Park, PA16802
| | - Rebecca Sear
- Department of Population Health, London School of Hygiene and Tropical Medicine, LondonWC1E 7HT, United Kingdom
| | - Edmond Seabright
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Ryan Schacht
- Department of Anthropology, East Carolina University, Greenville, NC27858
| | - Brooke Scelza
- Department of Anthropology, University of California, Los Angeles, CA90095
| | - Shane Scaggs
- Department of Anthropology, Ohio State University, Columbus, OH43210
| | - Jonathan Salerno
- Department of Human Dimensions of Natural Resources, Colorado State University, Fort Collins, CO80523
| | - Caissa Revilla-Minaya
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Daniel Redhead
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Anne Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC27708
| | - Benjamin Grant Purzycki
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of the Study of Religion, Aarhus University, Aarhus8000, Denmark
| | - Eleanor A. Power
- Santa Fe Institute, Santa Fe, NM87501
- Department of Methodology, London School of Economics and Political Science, LondonWC2A 2AE, United Kingdom
| | - Anne Pisor
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Anthropology, Washington State University, Pullman, WA99164
| | - Jenni Pettay
- Department of Biology, University of Turku, Turku20014, Finland
| | - Susan Perry
- Department of Anthropology, University of California, Los Angeles, CA90095
| | - Abigail E. Page
- Department of Population Health, London School of Hygiene and Tropical Medicine, LondonWC1E 7HT, United Kingdom
| | - Luis Pacheco-Cobos
- Facultad de Ciencias Biológicas y Agropecuarias, Universidad Veracruzana, Veracruz94294, Mexico
| | - Kathryn Oths
- Department of Anthropology, University of Alabama, Tuscaloosa, AL35487
| | - Seung-Yun Oh
- Korea Insurance Research Institute, Seoul150-606, Korea
| | - David Nolin
- Department of Sociology, University of Massachusetts, Amherst, MA01003
| | - Daniel Nettle
- Département d’Etudes Cognitives, Ecole Normale Supérieure, Université PSL, Paris75230, France
| | - Cristina Moya
- Department of Anthropology, University of California, Davis, CA95616
| | - Andrea Bamberg Migliano
- Institut für Anthropologie und Anthropologisches Museum, University of Zürich, Zürich8006, Switzerland
| | - Karl J. Mertens
- Department of Anthropology, Boise State University, Boise, ID83725
| | - Rita A. McNamara
- School of Psychology, Victoria University of Wellington, Wellington6012, New Zealand
| | - Richard McElreath
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Siobhan Mattison
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Eric Massengill
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Frank Marlowe
- Department of Biological Anthropology, University of Cambridge, CambridgeCB2 1TN, United Kingdom
| | - Felicia Madimenos
- Department of Anthropology, Queens College (CUNY), New York, NY11367
| | - Shane Macfarlan
- Department of Anthropology, University of Utah, Salt Lake City, UT84112
| | - Virpi Lummaa
- Department of Biology, University of Turku, Turku20014, Finland
| | - Roberto Lizarralde
- Facultad de Ciencias Económicas y Sociales, Universidad Central de Venezuela, Caracas1010A, Venezuela
| | - Ruizhe Liu
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
| | - Melissa A. Liebert
- Department of Anthropology, Northern Arizona University, Flagstaff, AZ86011
| | - Sheina Lew-Levy
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Psychology, Durham University, DurhamDH1 3LE, United Kingdom
| | - Paul Leslie
- Department of Anthropology, University of North Carolina, Chapel Hill, NC27599
| | | | - Karen Kramer
- Department of Anthropology, University of Utah, Salt Lake City, UT84112
| | - Jeremy Koster
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH45221
| | | | | | - A. Magdalena Hurtado
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ85287
| | - Kim Hill
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ85287
| | - Barry Hewlett
- Department of Anthropology, Washington State University, Pullman, WA99164
| | - Samuli Helle
- Department of Biology, University of Turku, Turku20014, Finland
| | | | | | - Michael Gurven
- Department of Anthropology, University of California, Santa Barbara, CA93106
| | | | - Russell Greaves
- Department of Anthropology, University of Utah, Salt Lake City, UT84112
| | - Christopher D. Golden
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Irene Godoy
- Department of Animal Behaviour, Bielefeld University, Bielefeld33615, Germany
| | - Mhairi Gibson
- Department of Anthropology and Archaeology, University of Bristol, BristolBS8 1QU, United Kingdom
| | - Claire El Mouden
- School of Anthropology and Museum Ethnography, University of Oxford, OxfordOX1 2JD, United Kingdom
| | - Mark Dyble
- Department of Anthropology, University College London, LondonWC1E 6BT, United Kingdom
| | - Patricia Draper
- School of Global Integrative Studies, University of Nebraska, Lincoln, NE68588
| | - Sean Downey
- Department of Anthropology, Ohio State University, Columbus, OH43210
| | | | | | - Stefani Crabtree
- Santa Fe Institute, Santa Fe, NM87501
- Department of Environment and Society, Utah State University, Logan, UT84322
| | - Carmen Cortez
- Department of Anthropology, University of California, Davis, CA95616
| | - Heidi Colleran
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Emma Cohen
- School of Anthropology and Museum Ethnography, University of Oxford, OxfordOX1 2JD, United Kingdom
| | - Gregory Clark
- Department of Economics, University of California, Davis, CA95616
| | | | - Mark A. Caudell
- Department of Anthropology, Washington State University, Pullman, WA99164
| | - Chelsea E. Carminito
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH45221
| | - John Bunce
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Adam Boyette
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | | | - Tami Blumenfield
- Department of Anthropology, University of New Mexico, Albuquerque, NM87131
- School of Ethnology and Sociology, Yunnan University, Yunnan650106, China
| | - Bret Beheim
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
| | - Stephen Beckerman
- Department of Anthropology, Pennsylvania State University, University Park, PA16802
| | - Quentin Atkinson
- School of Psychology, University of Auckland, Auckland1010, New Zealand
| | - Coren Apicella
- Department of Psychology, University of Pennsylvania, Philadelphia, PA19104
| | - Nurul Alam
- International Centre for Diarrheal Disease Research, Dhaka1000, Bangladesh
| | - Monique Borgerhoff Mulder
- Santa Fe Institute, Santa Fe, NM87501
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig04103, Germany
- Department of Anthropology, University of California, Davis, CA95616
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29
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Lawson DW, Alami S, Somefun OD. Gendered conflict in the human family. EVOLUTIONARY HUMAN SCIENCES 2023; 5:e12. [PMID: 37587929 PMCID: PMC10426121 DOI: 10.1017/ehs.2023.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 04/02/2023] [Indexed: 08/18/2023] Open
Abstract
Sexual conflict is a thriving area of animal behaviour research. Yet parallel research in the evolutionary human sciences remains underdeveloped and has become mired by controversy. In this special collection, we aim to invigorate the study of fitness-relevant conflicts between women and men, advocating for three synergistic research priorities. First, we argue that a commitment to diversity is required to innovate the field, achieve ethical research practice, and foster fruitful dialogue with neighbouring social sciences. Accordingly, we have prioritised issues of diversity as editors, aiming to stimulate new connections and perspectives. Second, we call for greater recognition that human sex/gender roles and accompanying conflict behaviours are both subject to natural selection and culturally determined. This motivates our shift in terminology from sexual to gendered conflict when addressing human behaviour, countering stubborn tendencies to essentialise differences between women and men and directing attention to the role of cultural practices, normative sanctions and social learning in structuring conflict battlegrounds. Finally, we draw attention to contemporary policy concerns, including the wellbeing consequences of marriage practices and the gendered implications of market integration. Focus on these themes, combined with attendance to the dangers of ethnocentrism, promises to inform culturally sensitive interventions promoting gender equality worldwide.
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Affiliation(s)
- David W Lawson
- Department of Anthropology, University of California Santa Barbara, USA
| | - Sarah Alami
- The School of Collective Intelligence, Mohammed VI Polytechnic University, Morocco
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30
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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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31
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Hatchett WJ, Jueterbock AO, Kopp M, Coyer JA, Coelho SM, Hoarau G, Lipinska AP. Evolutionary dynamics of sex-biased gene expression in a young XY system: insights from the brown alga genus Fucus. THE NEW PHYTOLOGIST 2023; 238:422-437. [PMID: 36597732 DOI: 10.1111/nph.18710] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Sex-biased gene expression is considered to be an underlying cause of sexually dimorphic traits. Although the nature and degree of sex-biased expression have been well documented in several animal and plant systems, far less is known about the evolution of sex-biased genes in more distant eukaryotic groups. Here, we investigate sex-biased gene expression in two brown algal dioecious species, Fucus serratus and Fucus vesiculosus, where male heterogamety (XX/XY) has recently emerged. We find that in contrast to evolutionary distant plant and animal lineages, male-biased genes do not experience high turnover rates, but instead reveal remarkable conservation of bias and expression levels between the two species, suggesting their importance in sexual differentiation. Genes with consistent male bias were enriched in functions related to gamete production, along with sperm competition and include three flagellar proteins under positive selection. We present one of the first reports, outside of the animal kingdom, showing that male-biased genes display accelerated rates of coding sequence evolution compared with female-biased or unbiased genes. Our results imply that evolutionary forces affect male and female sex-biased genes differently on structural and regulatory levels, resulting in unique properties of differentially expressed transcripts during reproductive development in Fucus algae.
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Affiliation(s)
- William J Hatchett
- Faculty of Biosciences and Aquaculture, Nord University, 8026, Bodø, Norway
| | | | - Martina Kopp
- Faculty of Biosciences and Aquaculture, Nord University, 8026, Bodø, Norway
| | - James A Coyer
- Shoals Marine Laboratory, University of New Hampshire, Durham, NH, 03824, USA
| | - Susana M Coelho
- CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Sorbonne Université, Station Biologique de Roscoff, 29680, Roscoff, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology, 72076, Tuebingen, Germany
| | - Galice Hoarau
- Faculty of Biosciences and Aquaculture, Nord University, 8026, Bodø, Norway
| | - Agnieszka P Lipinska
- CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Sorbonne Université, Station Biologique de Roscoff, 29680, Roscoff, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology, 72076, Tuebingen, Germany
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32
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Benenson JF, Markovits H. Married women with children experience greater intrasexual competition than their male counterparts. Sci Rep 2023; 13:4498. [PMID: 36934175 PMCID: PMC10024730 DOI: 10.1038/s41598-023-31816-0] [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: 07/22/2022] [Accepted: 03/17/2023] [Indexed: 03/20/2023] Open
Abstract
Human males are considered to be more competitive than females. However, females must also compete for resources necessary for their own and their offsprings' survival. Since females use more indirect forms of competition than males, comparing observable forms of competition may be misleading. One critical driver of competition is resource asymmetry. Since competition occurs primarily within sex, reactions to resource asymmetry with same-sex peers should provide an important measure of competitiveness. We asked 596 married participants, 25-45 years of age with at least one child from three different countries to evaluate how same-sex individuals they know would react to a target individual who had a valuable resource that the same-sex individuals did not have. Half the participants evaluated reactions to same-sex targets, while the other half evaluated reactions to other-sex targets. Participants reported that women would react more negatively than men to resource asymmetry with same-sex targets, but not other-sex targets. These results suggest that women may be even more competitive than men in contexts when important resources related to reproductive success are at stake.
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Affiliation(s)
- Joyce F Benenson
- Department of Human Evolutionary Biology, Harvard University, Cambridge, 02138, USA.
| | - Henry Markovits
- Département de Psychologie, Université du Québec à Montréal, Montréal, H3C 3P8, Canada
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33
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Fargevieille A, Grégoire A, Gomez D, Doutrelant C. Evolution of female colours in birds: The role of female cost of reproduction and paternal care. J Evol Biol 2023; 36:579-588. [PMID: 36702760 DOI: 10.1111/jeb.14150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 11/10/2022] [Accepted: 12/11/2022] [Indexed: 01/28/2023]
Abstract
Female ornamentation is frequently observed in animal species and is sometimes found as more evolutionary labile than male ornamentation. A complex array of factors may explain its presence and variation. Here we assessed the role of female cost of reproduction and paternal care. Both factors have been pinpointed as important by theoretical studies but have not been investigated yet in details at the interspecific level. We worked on 133 species of North temperate Passeriformes bird species for which both the clutch volume - here taken as the proxy of female cost of reproduction - and amount of paternal care are relatively well known. Using spectrometry, we measured the whole-body coloured plumage patches and quantified three metrics corresponding to brightness (i.e. achromatic component), colour chromaticity (i.e. intensity) and colour volume (i.e. diversity). We found a strong association between male and female colour metrics. Controlling for this association, we found additional small but detectable effects of both cost of reproduction and paternal care. First, females of species with more paternal care were slightly brighter. Second, the interaction between the level of paternal care and egg volume was correlated with female colour intensity: females with more paternal care were more chromatic, with this association mostly present when their investment in reproduction was low. Together these results suggest that female cost of reproduction and paternal care are part of the multiple factors explaining variation of female coloration, besides the strong covariation between male and female coloration.
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Affiliation(s)
| | - Arnaud Grégoire
- CEFE-CNRS UMR 5175, Université de Montpellier, Montpellier Cedex 5, France
| | - Doris Gomez
- CEFE-CNRS UMR 5175, Université de Montpellier, Montpellier Cedex 5, France
| | - Claire Doutrelant
- CEFE-CNRS UMR 5175, Université de Montpellier, Montpellier Cedex 5, France
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34
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Moschilla JA, Tomkins JL, Simmons LW. Among-individual variation in behaviour and its effect on reproductive success. Anim Behav 2023. [DOI: 10.1016/j.anbehav.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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35
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Carleial R, Pizzari T, Richardson DS, McDonald GC. Disentangling the causes of temporal variation in the opportunity for sexual selection. Nat Commun 2023; 14:1006. [PMID: 36813810 PMCID: PMC9947164 DOI: 10.1038/s41467-023-36536-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 02/06/2023] [Indexed: 02/24/2023] Open
Abstract
In principle, temporal fluctuations in the potential for sexual selection can be estimated as changes in intrasexual variance in reproductive success (i.e. the opportunity for selection). However, we know little about how opportunity measures vary over time, and the extent to which such dynamics are affected by stochasticity. We use published mating data from multiple species to investigate temporal variation in the opportunity for sexual selection. First, we show that the opportunity for precopulatory sexual selection typically declines over successive days in both sexes and shorter sampling periods lead to substantial overestimates. Second, by utilising randomised null models, we also find that these dynamics are largely explained by an accumulation of random matings, but that intrasexual competition may slow temporal declines. Third, using data from a red junglefowl (Gallus gallus) population, we show that declines in precopulatory measures over a breeding period were mirrored by declines in the opportunity for both postcopulatory and total sexual selection. Collectively, we show that variance-based metrics of selection change rapidly, are highly sensitive to sampling durations, and likely lead to substantial misinterpretation if used as indicators of sexual selection. However, simulations can begin to disentangle stochastic variation from biological mechanisms.
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Affiliation(s)
- Rômulo Carleial
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3SZ, UK. .,Science Directorate, Royal Botanic Gardens, Kew, Richmond, TW9 3AE, UK.
| | - Tommaso Pizzari
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3SZ, UK
| | | | - Grant C McDonald
- Department of Ecology, University of Veterinary Medicine Budapest, Budapest, 1077, Hungary.
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36
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Levelling as a Female-Biased Competitive Tactic. EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2023. [DOI: 10.1007/s40806-023-00355-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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37
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Goymann W, Brumm H, Kappeler PM. Biological sex is binary, even though there is a rainbow of sex roles: Denying biological sex is anthropocentric and promotes species chauvinism: Denying biological sex is anthropocentric and promotes species chauvinism. Bioessays 2023; 45:e2200173. [PMID: 36543364 DOI: 10.1002/bies.202200173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/02/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022]
Abstract
Biomedical and social scientists are increasingly calling the biological sex into question, arguing that sex is a graded spectrum rather than a binary trait. Leading science journals have been adopting this relativist view, thereby opposing fundamental biological facts. While we fully endorse efforts to create a more inclusive environment for gender-diverse people, this does not require denying biological sex. On the contrary, the rejection of biological sex seems to be based on a lack of knowledge about evolution and it champions species chauvinism, inasmuch as it imposes human identity notions on millions of other species. We argue that the biological definition of the sexes remains central to recognising the diversity of life. Humans with their unique combination of biological sex and gender are different from non-human animals and plants in this respect. Denying the concept of biological sex, for whatever cause, ultimately erodes scientific progress and may open the flood gates to "alternative truths."
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Affiliation(s)
- Wolfgang Goymann
- Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Henrik Brumm
- Research Group Animal Communication and Urban Ecology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Göttingen, Germany.,Department of Sociobiology/Anthropology, University of Göttingen, Göttingen, Germany
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38
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Tuschhoff E, Wiens JJ. Evolution of sexually selected traits across animals. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1042747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Sexual selection is thought to be a major driver of phenotypic diversity and diversification in animals, but large-scale evolutionary patterns in sexually selected (SS) traits remain largely unknown. Here, we survey and analyze the evolution of these traits across animal phylogeny. We find that female mate choice appears to be the most widespread mechanism of sexual selection, but male-male competition appears to be almost as frequent in chordates and male mate choice is also common in arthropods. Among sensory types, tactile traits appear to be most widespread whereas auditory traits are relatively uncommon. Rather than being ubiquitous or randomly distributed across animals, most of these different types of SS traits are confined to clades in arthropods and chordates, which form “hotspots” for the evolution of these diverse trait types. Thus, different sensory types show accelerated rates of evolution in these clades. Moreover, different types of SS traits are strongly correlated with each other in their evolution across animals. Finally, despite the intensive interest in the role of sexual selection in speciation, we find only limited support for the idea that SS traits drive large-scale patterns of diversification and species richness across all animals.
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39
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Kokko H, Jennions MD. Is more always better when it comes to mating? PLoS Biol 2023; 21:e3001955. [PMID: 36630323 PMCID: PMC9833505 DOI: 10.1371/journal.pbio.3001955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Fitness usually increases when a male mates with more females, but is the same true for females? A new meta-analysis in PLOS Biology shows that females, like males, tend to have a positive relationship between the number of mates and their reproductive output. But why?
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Affiliation(s)
- Hanna Kokko
- Department of Evolutionary Biology and Environmental Sciences, University of Zurich, Zurich, Switzerland,* E-mail:
| | - Michael D. Jennions
- Ecology & Evolution, Research School of Biology, The Australian National University, Canberra, Australia
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40
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Sexual selection in females and the evolution of polyandry. PLoS Biol 2023; 21:e3001916. [PMID: 36626380 PMCID: PMC9831318 DOI: 10.1371/journal.pbio.3001916] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 11/14/2022] [Indexed: 01/11/2023] Open
Abstract
Over the last decades, the field of sexual selection underwent a paradigm shift from sexual-stereotype thinking of "eager" males and "coy" females towards a more nuanced perspective acknowledging that not only males but also females can benefit from multiple mating and compete for mating partners. Yet, sexual selection in females is still considered a peculiarity, and the evolution of polyandry is often viewed to result from a higher mating interest of males. Here, we present meta-analytic evidence from 77 species across a broad range of animal taxa to demonstrate that female reproductive success is overall positively correlated with mating success, suggesting that females typically benefit from multiple mating. Importantly, we found that these fitness gains likely promote the evolution of polyandry. Our findings offer support for the idea that sexual selection is widespread in females and to play a key role for the evolution of animal mating systems. Thereby, our results extend our understanding of the evolutionary consequences of sexual reproduction and contribute to a more balanced view of how sexual selection operates in males and females.
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41
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Quero A, Gonzaga MO, Vasconcellos-Neto J, Moura RR. Offspring mortality factors and parental care efficiency of the spider Manogea porracea (Araneidae) in the Brazilian savanna. ETHOL ECOL EVOL 2023. [DOI: 10.1080/03949370.2022.2152197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Adilson Quero
- Pós-graduação em Ecologia, Conservação e Biodiversidade, Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - Marcelo O. Gonzaga
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
| | - João Vasconcellos-Neto
- Departamento de Biologia Animal, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Rafael R. Moura
- Núcleo de Extensão e Pesquisa em Ecologia e Evolução (NEPEE), Departamento de Ciências Agrárias e Naturais, Universidade do Estado de Minas Gerais, Ituiutaba, MG, Brazil
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42
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Stanbrook E, Fitzpatrick JL, Balshine S, Shultz S. The evolution of monogamy in cichlids and marine reef fishes. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1045383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Although several hypotheses have been proposed to explain the emergence of social monogamy, its origin is still intensely debated. Monogamy has many potential drivers, but evolutionary causality among them remains unclear. Using phylogenetic comparative methods within a Bayesian framework we explored the evolution of monogamy in cichlids and in marine reef fishes because, while both groups are characterised by unusually high incidence of social monogamy, they face very different ecological challenges. For each group, we examined four classic hypotheses that explain the evolution of monogamy: female dispersal, male mate guarding, female–female intolerance, and the biparental care hypotheses. We also explored whether the ecological traits of diet and shelter use are evolutionarily coupled with these hypotheses or with monogamy. First, we found that the evolution of monogamy was predicted by male territoriality in cichlids and simultaneous male and female territoriality in marine reef fishes. We suggest that these results provide support for the male mate guarding hypothesis in cichlids and female–female intolerance hypothesis in marine reef fishes. Second, we demonstrate clear evidence against the biparental care hypothesis, as biparental care was a consequence, not a cause, of monogamy in our analyses. Third, as female dispersal drove the loss of monogamy in both cichlids and marine reef fishes, this suggests the female dispersal hypothesis is not driving the evolution of monogamy in either group. These findings in two highly-monogamous fish taxa largely support prior findings from primate and bird comparative studies and provide novel large-scale evidence for a link between mate guarding and the evolution of monogamy.
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43
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Collier M, Albery GF, McDonald GC, Bansal S. Pathogen transmission modes determine contact network structure, altering other pathogen characteristics. Proc Biol Sci 2022; 289:20221389. [PMID: 36515115 PMCID: PMC9748778 DOI: 10.1098/rspb.2022.1389] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Pathogen traits can vary greatly and heavily impact the ability of a pathogen to persist in a population. Although this variation is fundamental to disease ecology, little is known about the evolutionary pressures that drive these differences, particularly where they interact with host behaviour. We hypothesized that host behaviours relevant to different transmission routes give rise to differences in contact network structure, constraining the space over which pathogen traits can evolve to maximize fitness. Our analysis of 232 contact networks across mammals, birds, reptiles, amphibians, arthropods, fish and molluscs found that contact network topology varies by contact type, most notably in networks that are representative of fluid-exchange transmission. Using infectious disease model simulations, we showed that these differences in network structure suggest pathogens transmitted through fluid-exchange contact types will need traits associated with high transmissibility to successfully proliferate, compared to pathogens that transmit through other types of contact. These findings were supported through a review of known traits of pathogens that transmit in humans. Our work demonstrates that contact network structure may drive the evolution of compensatory pathogen traits according to transmission strategy, providing essential context for understanding pathogen evolution and ecology.
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Affiliation(s)
- Melissa Collier
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Gregory F. Albery
- Department of Biology, Georgetown University, Washington, DC, USA,Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Grant C. McDonald
- Department of Ecology, University of Veterinary Medicine Budapest, Budapest, Hungary
| | - Shweta Bansal
- Department of Biology, Georgetown University, Washington, DC, USA
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44
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Barbot E, Dufaÿ M, Tonnabel J, Godé C, De Cauwer I. On the function of flower number: disentangling fertility from pollinator-mediated selection. Proc Biol Sci 2022; 289:20221987. [PMID: 36448279 PMCID: PMC9709571 DOI: 10.1098/rspb.2022.1987] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/03/2022] [Indexed: 12/03/2022] Open
Abstract
In animal-pollinated angiosperms, the 'male-function' hypothesis claims that male reproductive success (RS) should benefit from large floral displays, through pollinator attraction, while female RS is expected to be mainly limited by resource availability. As appealing as this theory might be, studies comparing selection strength on flower number in both sexes rarely document the expected asymmetry. This discrepancy could arise because flower number impacts both pollinator attraction and overall gamete number. In this study, we artificially manipulate floral displays to disentangle the fertility versus pollinator attraction components of selection, both in terms of mating and RS. In females, flower number was under strong fertility selection, as predicted in the absence of pollen limitation. By contrast, in males, flower number was mainly under sexual selection, which in turn increased male RS. However, these selection patterns were not different in males with artificially increased floral displays. This suggests that sexual selection acting on flower number in males does not occur because flower number increases pollinator attraction, but rather because more pollen is available to disperse on more mates. Our study illustrates the power of disentangling various components of selection with potentially sex-specific effects for understanding the evolution of sexual dimorphism.
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Affiliation(s)
- Estelle Barbot
- Univ. Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, F-59000 Lille, France
- ISEM, Univ. Montpellier, CNRS, IRD, Montpellier, France
| | - Mathilde Dufaÿ
- CEFE, Univ. Montpellier, CNRS, Univ. Paul Valéry Montpellier 3, EPHE, IRD, Montpellier, France
| | - Jeanne Tonnabel
- ISEM, Univ. Montpellier, CNRS, IRD, Montpellier, France
- CEFE, Univ. Montpellier, CNRS, Univ. Paul Valéry Montpellier 3, EPHE, IRD, Montpellier, France
| | - Cécile Godé
- Univ. Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, F-59000 Lille, France
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45
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Schacht R, Beissinger SR, Wedekind C, Jennions MD, Geffroy B, Liker A, Kappeler PM, Weissing FJ, Kramer KL, Hesketh T, Boissier J, Uggla C, Hollingshaus M, Székely T. Adult sex ratios: causes of variation and implications for animal and human societies. Commun Biol 2022; 5:1273. [PMID: 36402823 PMCID: PMC9675760 DOI: 10.1038/s42003-022-04223-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 11/03/2022] [Indexed: 11/21/2022] Open
Abstract
Converging lines of inquiry from across the social and biological sciences target the adult sex ratio (ASR; the proportion of males in the adult population) as a fundamental population-level determinant of behavior. The ASR, which indicates the relative number of potential mates to competitors in a population, frames the selective arena for competition, mate choice, and social interactions. Here we review a growing literature, focusing on methodological developments that sharpen knowledge of the demographic variables underlying ASR variation, experiments that enhance understanding of the consequences of ASR imbalance across societies, and phylogenetic analyses that provide novel insights into social evolution. We additionally highlight areas where research advances are expected to make accelerating contributions across the social sciences, evolutionary biology, and biodiversity conservation.
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Affiliation(s)
- Ryan Schacht
- grid.255364.30000 0001 2191 0423Department of Anthropology, East Carolina University, Greenville, NC USA
| | - Steven R. Beissinger
- grid.47840.3f0000 0001 2181 7878Department of Environmental Science, Policy and Management and Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720 USA
| | - Claus Wedekind
- grid.9851.50000 0001 2165 4204Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Michael D. Jennions
- grid.1001.00000 0001 2180 7477Ecology & Evolution, Research School of Biology, The Australian National University, Acton, Canberra 2601 Australia
| | - Benjamin Geffroy
- MARBEC Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - András Liker
- grid.7336.10000 0001 0203 5854ELKH-PE Evolutionary Ecology Research Group, University of Pannonia, 8210 Veszprém, Hungary ,grid.7336.10000 0001 0203 5854Behavioural Ecology Research Group, Center for Natural Sciences, University of Pannonia, 8210 Veszprém, Hungary
| | - Peter M. Kappeler
- grid.418215.b0000 0000 8502 7018Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute of Primate Biology, 37077 Göttingen, Germany ,grid.7450.60000 0001 2364 4210Department of Sociobiology/Anthropology, University of Göttingen, 37077 Göttingen, Germany
| | - Franz J. Weissing
- grid.4830.f0000 0004 0407 1981Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Karen L. Kramer
- grid.223827.e0000 0001 2193 0096Department of Anthropology, University of Utah, Salt Lake City, UT USA
| | - Therese Hesketh
- grid.83440.3b0000000121901201Institute of Global Health, University College London, London, UK ,grid.13402.340000 0004 1759 700XCentre for Global Health, Zhejiang University School of Medicine, Hangzhou, P.R. China
| | - Jérôme Boissier
- grid.4444.00000 0001 2112 9282IHPE Univ Perpignan Via Domitia, CNRS, Ifremer, Univ Montpellier, Perpignan, France
| | - Caroline Uggla
- grid.10548.380000 0004 1936 9377Stockholm University Demography Unit, Sociology Department, Stockholm University, 106 91 Stockholm, Sweden
| | - Mike Hollingshaus
- grid.223827.e0000 0001 2193 0096Kem C. Gardner Policy Institute, David Eccles School of Business, University of Utah, Salt Lake City, UT USA
| | - Tamás Székely
- grid.7340.00000 0001 2162 1699Milner Centre for Evolution, University of Bath, Bath, BA2 7AY UK ,grid.7122.60000 0001 1088 8582ELKH-DE Reproductive Strategies Research Group, Department of Zoology and Human Biology, University of Debrecen, H-4032 Debrecen, Hungary
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46
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Kwok A, Dorken ME. Sexual selection on male but not female function in monoecious and dioecious populations of broadleaf arrowhead ( Sagittaria latifolia). Proc Biol Sci 2022; 289:20220919. [PMID: 36350202 PMCID: PMC9653219 DOI: 10.1098/rspb.2022.0919] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 10/12/2022] [Indexed: 09/30/2023] Open
Abstract
Direct measures of sexual selection in plants are rare and complicated by immobility and modular growth. For plants, instantaneous measures of fitness typically scale with size, but covariances between size and mating success could obscure the detection of sexual selection. We measured the magnitude of sexual selection in a monoecious and a dioecious population of the clonal plant Sagittaria latifolia using Bateman gradients (ßss). These gradients were calculated using parentage analysis and residual regression to account for the effects of shoot and clone size on mating and reproductive success. In both populations, (i) there was greater promiscuity via male function than via female function and (ii) ßss were positive, with significant associations between mating and reproductive success for male but not female function. Moreover, estimated βss were similar for the monoecious and dioecious populations, possibly because non-overlapping female and male sex phases in hermaphroditic S. latifolia reduced the scope for interference between sex functions during mating. This study builds on previous studies of selection on plant mating traits, and of sexual selection under experimental conditions, by showing that sexual selection can operate in natural populations of plants, including populations of hermaphrodites.
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Affiliation(s)
- Allison Kwok
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada K9J 0G2
| | - Marcel E. Dorken
- Department of Biology, Trent University, Peterborough, ON, Canada K9J 0G2
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Winkler L, Janicke T. Diet quality impairs male and female reproductive performance and affects the opportunity for selection in an insect model. Ecol Evol 2022; 12:e9533. [DOI: 10.1002/ece3.9533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 10/22/2022] [Accepted: 11/01/2022] [Indexed: 11/25/2022] Open
Affiliation(s)
| | - Tim Janicke
- Applied Zoology TU Dresden Dresden Germany
- Centre d'Écologie Fonctionnelle et Évolutive CNRS, Univ Montpellier, EPHE, IRD Montpellier Cedex 05 France
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48
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The effect of sex, age and boldness on inhibitory control. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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49
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Browne JH, Gwynne DT. Paternity sharing in insects with female competition for nuptial gifts. Ecol Evol 2022; 12:e9463. [PMID: 36329813 PMCID: PMC9618826 DOI: 10.1002/ece3.9463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 09/20/2022] [Accepted: 10/10/2022] [Indexed: 11/26/2022] Open
Abstract
Male parental investment is expected to be associated with high confidence of paternity. Studies of species with exclusive male parental care have provided support for this hypothesis because mating typically co‐occurs with each oviposition, allowing control over paternity and the allocation of care. However, in systems where males invest by feeding mates (typically arthropods), mating (and thus the investment) is separated from egg‐laying, resulting in less control over insemination, as male ejaculates compete with rival sperm stored by females, and a greater risk of investing in unrelated offspring (cuckoldry). As strong selection on males to increase paternity would compromise the fitness of all a female's other mates that make costly nutrient contributions, paternity sharing (males not excluded from siring offspring) is an expected outcome of sperm competition. Using wild‐caught females in an orthopteran and a dipteran species, in which sexually selected, ornamented females compete for male nuptial food gifts needed for successful reproduction, we examined paternity patterns and compared them with findings in other insects. We used microsatellite analysis of offspring (lifetime reproduction in the orthopteran) and stored sperm from wild‐caught females in both study species. As predicted, there was evidence of shared paternity as few males failed to sire offspring. Further support for paternity sharing is the lack of last‐male sperm precedence in our study species. Although paternity was not equal among sires, our estimates of paternity bias were similar to other insects with valuable nuptial gifts and contrasted with the finding that males are frequently excluded from siring offspring in species where males supply little more than sperm. This suggests paternity bias may be reduced in nuptial‐gift systems and may help facilitate the evolution of these paternal investments.
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Affiliation(s)
- Jessica H. Browne
- Department of Ecology and Evolutionary BiologyUniversity of Toronto MississaugaMississaugaOntarioCanada,Department of BiologyMount Allison UniversitySackvilleNew BrunswickCanada
| | - Darryl T. Gwynne
- Department of Ecology and Evolutionary BiologyUniversity of Toronto MississaugaMississaugaOntarioCanada
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Variability in energy expenditure is much greater in males than females. J Hum Evol 2022; 171:103229. [PMID: 36115145 PMCID: PMC9791915 DOI: 10.1016/j.jhevol.2022.103229] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 06/01/2022] [Accepted: 06/12/2022] [Indexed: 11/24/2022]
Abstract
In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.
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