1
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Rueger T, MacDonald C, Harrison HB, Gardiner NM, Jones GP, Mills SC. Strength of Sexual Selection and Sex Roles Vary between Social Groups in a Coral Reef Cardinalfish. Am Nat 2024; 204:289-303. [PMID: 39179236 DOI: 10.1086/731422] [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: 08/26/2024]
Abstract
AbstractThe strength and direction of sexual selection can vary among populations. However, spatial variability is rarely explored at the level of the social group. Here we investigate sexual selection and sex roles in the paternally mouthbrooding, socially monogamous, and site-attached pajama cardinalfish, Sphaeramia nematoptera. Females were larger and more aggressive and had a longer dorsal fin filament, indicating reversed sex roles. At the scale of social groups, we show that the Bateman gradient and reproductive variance depend on the sex ratio and size of groups. In small and medium-sized groups with balanced or male-biased sex ratios, Bateman gradients were steeper for females, whereas gradients were equally steep for both sexes in large groups or when the sex ratio was female biased. For both sexes, reproductive variance increased with group size and with a higher male-to-female sex ratio. In S. nematoptera, mating opportunities outside the socially monogamous pair appear to impact sexual selection. We conclude that strength and direction of sexual selection can be masked by social dynamics in group-living species when considering only population and large-scale demographic processes.
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2
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Revathi Venkateswaran V, Gokhale CS, Mangel M, Eliassen S. Effects of time spent in pregnancy or brooding on immunocompetence. Ecol Evol 2024; 14:e10764. [PMID: 38187919 PMCID: PMC10767163 DOI: 10.1002/ece3.10764] [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: 05/19/2023] [Revised: 10/05/2023] [Accepted: 11/10/2023] [Indexed: 01/09/2024] Open
Abstract
Sexes of a species may show different characteristics beyond the differences in their sexual organs and such sexual dimorphism often occurs in the level of immune response when exposed to pathogens (immunocompetence). In general, females have increased longevity relative to males, which is associated with higher immunocompetence. However, males have higher immunocompetence in some species, such as pipefishes and seahorses. Experimental evidence suggests that this could be because males, rather than females, carry fertilized eggs to birth in these species. This observation suggests that an increase in immunocompetence may be related to the level of parental investment and not to a particular sex. We use state-dependent life-history theory to study optimal investment in offspring production relative to parent immunocompetence, varying the relative time that a parent spends in brooding or pregnancy within a breeding cycle. When offspring is dependent on a parent's survival for a large part of the breeding cycle, we predict higher investments in immunity and longer life expectancies.
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Affiliation(s)
- Vandana Revathi Venkateswaran
- Research Group for Theoretical Models of Eco‐evolutionary Dynamics, Department of Evolutionary TheoryMax Planck Institute for Evolutionary BiologyPlönGermany
- Department of Plant Biology, School of Integrative BiologyUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
| | - Chaitanya S. Gokhale
- Research Group for Theoretical Models of Eco‐evolutionary Dynamics, Department of Evolutionary TheoryMax Planck Institute for Evolutionary BiologyPlönGermany
| | - Marc Mangel
- Institute of Marine Sciences and Department of Applied MathematicsUniversity of CaliforniaSanta CruzCaliforniaUSA
- Theoretical Ecology Group, Department of Biological SciencesUniversity of BergenBergenNorway
| | - Sigrunn Eliassen
- Theoretical Ecology Group, Department of Biological SciencesUniversity of BergenBergenNorway
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3
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van Eyndhoven F, Cameron EZ, Flanagan SP. High rates of male courtship in a female-ornamented pipefish. ROYAL SOCIETY OPEN SCIENCE 2023; 10:231428. [PMID: 37885981 PMCID: PMC10598436 DOI: 10.1098/rsos.231428] [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: 09/21/2023] [Accepted: 10/04/2023] [Indexed: 10/28/2023]
Abstract
In species with sex-specific signalling traits that appear to be ornamental (i.e. are conspicuous and with no obvious natural selection benefit), the ornamented sex typically initiates courtship and is most active in courtship. Here, we report for the first time courtship displays in the extremely sexually dimorphic, female-ornamented wide-bodied pipefish (Stigmatopora nigra), revealing unexpected behaviours. Females use their sex-specific ornament during courtship displays, as expected, but rarely in female-female interactions. Surprisingly, males initiated 61% of reciprocated courtship bouts and chased females in 17% of the bouts. This chasing behaviour could be a form of male harassment or be indicative of female disinterest in ardent males, either of which was unexpected to be found in this female-ornamented species. Our results highlight the need to study the details of species' behaviours in considering the potential roles of sexual selection and sexual conflict in shaping sexual dimorphism.
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Affiliation(s)
- Fleur van Eyndhoven
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Elissa Z. Cameron
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Sarah P. Flanagan
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
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4
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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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5
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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: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [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
- Department of Anthropology, East Carolina University, Greenville, NC, USA.
| | - Steven R Beissinger
- Department of Environmental Science, Policy and Management and Museum of Vertebrate Zoology, University of California, Berkeley, CA, 94720, USA
| | - Claus Wedekind
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland
| | - Michael D Jennions
- Ecology & 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
- ELKH-PE Evolutionary Ecology Research Group, University of Pannonia, 8210, Veszprém, Hungary
- Behavioural Ecology Research Group, Center for Natural Sciences, University of Pannonia, 8210, Veszprém, Hungary
| | - Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute of Primate Biology, 37077, Göttingen, Germany
- Department of Sociobiology/Anthropology, University of Göttingen, 37077, Göttingen, Germany
| | - Franz J Weissing
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Karen L Kramer
- Department of Anthropology, University of Utah, Salt Lake City, UT, USA
| | - Therese Hesketh
- Institute of Global Health, University College London, London, UK
- Centre for Global Health, Zhejiang University School of Medicine, Hangzhou, P.R. China
| | - Jérôme Boissier
- IHPE Univ Perpignan Via Domitia, CNRS, Ifremer, Univ Montpellier, Perpignan, France
| | - Caroline Uggla
- Stockholm University Demography Unit, Sociology Department, Stockholm University, 106 91, Stockholm, Sweden
| | - Mike Hollingshaus
- Kem C. Gardner Policy Institute, David Eccles School of Business, University of Utah, Salt Lake City, UT, USA
| | - Tamás Székely
- Milner Centre for Evolution, University of Bath, Bath, BA2 7AY, UK.
- ELKH-DE Reproductive Strategies Research Group, Department of Zoology and Human Biology, University of Debrecen, H-4032, Debrecen, Hungary.
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6
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Azad T, Alonzo SH, Bonsall MB, Klug H. Life history, mating dynamics and the origin of parental care. J Evol Biol 2021; 35:379-390. [PMID: 34783118 DOI: 10.1111/jeb.13959] [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: 03/30/2021] [Revised: 10/14/2021] [Accepted: 10/25/2021] [Indexed: 11/29/2022]
Abstract
Parental care, mating dynamics and life history co-evolve. Understanding the diversity of reproductive patterns found in nature is a major focus of evolutionary ecology research. Previous research suggests that the origin of parental care of eggs will be favoured when egg and adult death rates and juvenile survival are relatively high. However, the previous research that explored the link between care and life history did not account for among-species variation in mating dynamics. As mating dynamics are generally expected to influence care, we explore, theoretically, the life-history conditions (stage-specific rates of maturation and survival) that favour parental care across three mating scenarios: reproductive rate (1) is unaffected by males (assuming that some males are present), (2) increases as male abundance increases or (3) decreases as male abundance increases. Across scenarios, all forms of care were most strongly favoured when egg and adult death rates, juvenile survival and female egg maturation rates were relatively high. When reproductive rate was unaffected by male abundance or increased as male abundance increased, as we might expect in systems in which females are mate-limited, all forms of care were most strongly favoured when male egg maturation rate (i.e. the rate at which male eggs develop, mature and hatch) was moderate or high. When greater male abundance inhibited reproduction, which might occur in systems with intense male-male competition, all forms of care were most strongly favoured when male egg maturation rate was low-to-moderate. These results suggest that life history affects the evolution of parental care, and sex-specific life history can interact with mating dynamics to influence the origin of care.
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Affiliation(s)
- Tamjeed Azad
- Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, Chattanooga, Tennessee, USA.,Department of Computer Science, Columbia University, New York, New York, USA
| | - Suzanne H Alonzo
- Ecology and Evolutionary Biology Department, University of California Santa Cruz, Santa Cruz, California, USA.,Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, USA
| | - Michael B Bonsall
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford, UK.,St. Peter's College, University of Oxford, Oxford, UK
| | - Hope Klug
- Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, Chattanooga, Tennessee, USA.,SimCenter, University of Tennessee at Chattanooga, Chattanooga, Tennessee, USA
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7
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Fritzsche K, Henshaw JM, Johnson BD, Jones AG. The 150th anniversary of The Descent of Man: Darwin and the impact of sex-role reversal on sexual selection research. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The year 2021 marks the 150th anniversary of the publication of Charles Darwin’s extraordinary book The Descent of Man and Selection in Relation to Sex. Here, we review the history and impact of a single profound insight from The Descent of Man: that, in some few species, females rather than males compete for access to mates. In other words, these species are ‘sex-role reversed’ with respect to mating competition and sexual selection compared to the majority of species in which sexual selection acts most strongly on males. Over the subsequent 150 years, sex-role-reversed species have motivated multiple key conceptual breakthroughs in sexual selection. The surprising mating dynamics of such species challenged scientists’ preconceptions, forcing them to examine implicit assumptions and stereotypes. This wider worldview has led to a richer and more nuanced understanding of animal mating systems and, in particular, to a proper appreciation for the fundamental role that females play in shaping these systems. Sex-role-reversed species have considerable untapped potential and will continue to contribute to sexual selection research in the decades to come.
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Affiliation(s)
- Karoline Fritzsche
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104 Freiburg, Germany
| | - Jonathan M Henshaw
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104 Freiburg, Germany
| | | | - Adam G Jones
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA
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8
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Sexual Selection: Evolutionary Foundations. Anim Behav 2021. [DOI: 10.1007/978-3-030-82879-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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9
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Morimoto J. Bateman (1948): was it all wrong? A comment on Hoquet (2020). Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.04.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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10
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Hoquet T. Bateman's principles: why biology needs history and philosophy. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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12
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Whittington CM, Friesen CR. The evolution and physiology of male pregnancy in syngnathid fishes. Biol Rev Camb Philos Soc 2020; 95:1252-1272. [PMID: 32372478 DOI: 10.1111/brv.12607] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 12/24/2022]
Abstract
The seahorses, pipefishes and seadragons (Syngnathidae) are among the few vertebrates in which pregnant males incubate developing embryos. Syngnathids are popular in studies of sexual selection, sex-role reversal, and reproductive trade-offs, and are now emerging as valuable comparative models for the study of the biology and evolution of reproductive complexity. These fish offer the opportunity to examine the physiology, behavioural implications, and evolutionary origins of embryo incubation, independent of the female reproductive tract and female hormonal milieu. Such studies allow us to examine flexibility in regulatory systems, by determining whether the pathways underpinning female pregnancy are also co-opted in incubating males, or whether novel pathways have evolved in response to the common challenges imposed by incubating developing embryos and releasing live young. The Syngnathidae are also ideal for studies of the evolution of reproductive complexity, because they exhibit multiple parallel origins of complex reproductive phenotypes. Here we assay the taxonomic distribution of syngnathid parity mode, examine the selective pressures that may have led to the emergence of male pregnancy, describe the biology of syngnathid reproduction, and highlight pressing areas for future research. Experimental tests of a range of hypotheses, including many generated with genomic tools, are required to inform overarching theories about the fitness implications of pregnancy and the evolution of male pregnancy. Such information will be widely applicable to our understanding of fundamental reproductive and evolutionary processes in animals.
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Affiliation(s)
- Camilla M Whittington
- The University of Sydney, School of Life and Environmental Sciences, Sydney, New South Wales, 2006, Australia.,The University of Sydney, Sydney School of Veterinary Science, Sydney, New South Wales, 2006, Australia
| | - Christopher R Friesen
- The University of Wollongong, School of Earth, Atmospheric and Life Sciences, Faculty of Science, Medicine and Health, Wollongong, New South Wales, 2522, Australia.,Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales, 2522, Australia
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13
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Louder MIM, Hauber ME, Louder ANA, Hoover JP, Schelsky WM. Greater opportunities for sexual selection in male than in female obligate brood parasitic birds. J Evol Biol 2019; 32:1310-1315. [PMID: 31568626 DOI: 10.1111/jeb.13537] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 08/25/2019] [Indexed: 11/28/2022]
Abstract
Females are expected to have evolved to be more discriminatory in mate choice than males as a result of greater reproductive investment into larger gametes (eggs vs. sperm). In turn, males are predicted to be more promiscuous than females, showing both a larger variance in the number of mates and a greater increase in reproductive success with more mates, yielding more intense sexual selection on males vs. females (Bateman's Paradigm). However, sex differences in costly parental care strategies can either reinforce or counteract the initial asymmetry in reproductive investment, which may be one cause for some studies failing to conform with predictions of Bateman's Paradigm. For example, in many bird species with small female-biased initial investment but extensive biparental care, both sexes should be subject to similar strengths of sexual selection because males and females are similarly restricted in their ability to pursue additional mates. Unlike 99% of avian species, however, obligate brood parasitic birds lack any parental care in either sex, predicting a conformation to Bateman's Paradigm. Here we use microsatellite genotyping to demonstrate that in brood parasitic brown-headed cowbirds (Molothrus ater), per capita annual reproductive success increases with the number of mates in males, but not in females. Furthermore, also as predicted, the variance of the number of mates and offspring is greater in males than in females. Thus, contrary to previous findings in this species, our results conform to predictions of the Bateman's Paradigm for taxa without parental care.
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Affiliation(s)
- Matthew I M Louder
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Mark E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, Champaign, IL, USA.,Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Amber N A Louder
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Jeffrey P Hoover
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Wendy M Schelsky
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA
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14
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Henshaw JM, Fromhage L, Jones AG. Sex roles and the evolution of parental care specialization. Proc Biol Sci 2019; 286:20191312. [PMID: 31455191 DOI: 10.1098/rspb.2019.1312] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Males and females are defined by the relative size of their gametes (anisogamy), but secondary sexual dimorphism in fertilization, parental investment and mating competition is widespread and often remarkably stable over evolutionary timescales. Recent theory has clarified the causal connections between anisogamy and the most prevalent differences between the sexes, but deviations from these patterns remain poorly understood. Here, we study how sex differences in parental investment and mating competition coevolve with parental care specialization. Parental investment often consists of two or more distinct activities (e.g. provisioning and defence) and parents may care more efficiently by specializing in a subset of these activities. Our model predicts that efficient care specialization broadens the conditions under which biparental investment can evolve in lineages that historically had uniparental care. Major transitions in sex roles (e.g. from female-biased care with strong male mating competition to male-biased care with strong female competition) can arise following ecologically induced changes in the costs or benefits of different care types, or in the sex ratio at maturation. Our model provides a clear evolutionary mechanism for sex-role transitions, but also predicts that such transitions should be rare. It consequently contributes towards explaining widespread phylogenetic inertia in parenting and mating systems.
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Affiliation(s)
- Jonathan M Henshaw
- Department of Biological Sciences, University of Idaho, 875 Perimeter MS 3051, Moscow, ID, USA.,Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Finland
| | - Lutz Fromhage
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Finland
| | - Adam G Jones
- Department of Biological Sciences, University of Idaho, 875 Perimeter MS 3051, Moscow, ID, USA
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15
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Masonjones H, Rose E, Elson J, Roberts B, Curtis-Quick J. High density, early maturing, and morphometrically unique Hippocampus erectus population makes a Bahamian pond a priority site for conservation. ENDANGER SPECIES RES 2019. [DOI: 10.3354/esr00949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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16
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Scheepers MJ, Gouws G. Mating System, Reproductive Success, and Sexual Selection in Bluntnose Klipfishes (Clinus cottoides). J Hered 2019; 110:351-360. [PMID: 30726981 DOI: 10.1093/jhered/esz008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/31/2019] [Indexed: 11/14/2022] Open
Abstract
A critical part of the sexual selection process in animals is the genetic mating system. Quantifying mating systems, especially in species with cryptic life histories can be challenging. One approach is to use genotypic markers and accurate parentage analysis, along with methods to account for bias when sampling natural populations, to calculate sexual selection metrics derived from Bateman's principles. In this study, 3 microsatellites were used to genotype 48 adults (23 female and 25 male) and 342 offspring from known mothers of live-bearing bluntnose klipfish. Parentage analysis was performed to interpret mating and reproductive success for both sexes. Metrics quantified were the opportunity for selection (I), the opportunity for sexual selection (Is), absolute (βss), and standardized (β'ss) Bateman gradients and the maximum intensity of precopulatory sexual selection (s'max). Multiple mating by both sexes were revealed by parentage analysis. However, females did not show significant Bateman gradients or a significant maximum intensity of precopulatory sexual selection (s'max), whereas male sexual selection metrics were all significantly greater than 0. These results suggest a polygynandrous mating system for this species. There is an opportunity for sexual selection to act on males but not females in this population, which is evolutionary tied to anisogamy, parental investment, and sex roles.
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Affiliation(s)
- Martinus Johannes Scheepers
- Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa
- National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB), South Africa
| | - Gavin Gouws
- National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB), South Africa
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17
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Janicke T, Ritchie MG, Morrow EH, Marie-Orleach L. Sexual selection predicts species richness across the animal kingdom. Proc Biol Sci 2019; 285:rspb.2018.0173. [PMID: 29720412 DOI: 10.1098/rspb.2018.0173] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/10/2018] [Indexed: 12/13/2022] Open
Abstract
Our improving knowledge of the animal tree of life consistently demonstrates that some taxa diversify more rapidly than others, but what contributes to this variation remains poorly understood. An influential hypothesis proposes that selection arising from competition for mating partners plays a key role in promoting speciation. However, empirical evidence showing a link between proxies of this sexual selection and species richness is equivocal. Here, we collected standardized metrics of sexual selection for a broad range of animal taxa, and found that taxonomic families characterized by stronger sexual selection on males show relatively higher species richness. Thus, our data support the hypothesis that sexual selection elevates species richness. This could occur either by promoting speciation and/or by protecting species against extinction.
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Affiliation(s)
- Tim Janicke
- Evolution, Behaviour and Environment Group, School of Life Sciences, University of Sussex, Brighton, UK.,Centre d'Écologie Fonctionnelle et Évolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, École Pratique des Hautes Études, 34090 Montpellier, France
| | - Michael G Ritchie
- Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews, UK
| | - Edward H Morrow
- Evolution, Behaviour and Environment Group, School of Life Sciences, University of Sussex, Brighton, UK
| | - Lucas Marie-Orleach
- Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews, UK
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18
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Hare RM, Simmons LW. Sexual selection and its evolutionary consequences in female animals. Biol Rev Camb Philos Soc 2018; 94:929-956. [DOI: 10.1111/brv.12484] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/31/2018] [Accepted: 11/02/2018] [Indexed: 01/01/2023]
Affiliation(s)
- Robin M. Hare
- Centre for Evolutionary Biology, School of Biological Sciences University of Western Australia 35 Stirling Highway, Perth, 6009 Australia
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences University of Western Australia 35 Stirling Highway, Perth, 6009 Australia
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19
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Mobley KB, Morrongiello JR, Warr M, Bray DJ, Wong BBM. Female ornamentation and the fecundity trade-off in a sex-role reversed pipefish. Ecol Evol 2018; 8:9516-9525. [PMID: 30377519 PMCID: PMC6194251 DOI: 10.1002/ece3.4459] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 07/14/2018] [Accepted: 07/20/2018] [Indexed: 11/12/2022] Open
Abstract
Sexual ornaments found only in females are a rare occurrence in nature. One explanation for this is that female ornaments are costly to produce and maintain and, therefore, females must trade-off resources related to reproduction to promote ornament expression. Here, we investigate whether a trade-off exists between female ornamentation and fecundity in the sex-role reversed, wide-bodied pipefish, Stigmatopora nigra. We measured two components of the disk-shaped, ventral-striped female ornament, body width, and stripe thickness. After controlling for the influence of body size, we found no evidence of a cost of belly width or stripe thickness on female fecundity. Rather, females that have larger ornaments have higher fecundity and thus accurately advertise their reproductive value to males without incurring a cost to fecundity. We also investigated the relationship between female body size and egg size and found that larger females suffer a slight decrease in egg size and fecundity, although this decrease was independent of female ornamentation. More broadly, considered in light of similar findings in other taxa, lack of an apparent fecundity cost of ornamentation in female pipefish underscores the need to revisit theoretical assumptions concerning the evolution of female ornamentation.
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Affiliation(s)
- Kenyon B. Mobley
- Department of Evolutionary EcologyMax Planck Institute for Evolutionary BiologyPlönGermany
| | | | - Matthew Warr
- School of Biological SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Dianne J. Bray
- Vertebrate ZoologyMuseum VictoriaMelbourneVictoriaAustralia
| | - Bob B. M. Wong
- School of Biological SciencesMonash UniversityMelbourneVictoriaAustralia
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20
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Amundsen T. Sex roles and sexual selection: lessons from a dynamic model system. Curr Zool 2018; 64:363-392. [PMID: 30402079 PMCID: PMC6007278 DOI: 10.1093/cz/zoy036] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 04/24/2018] [Indexed: 12/21/2022] Open
Abstract
Our understanding of sexual selection has greatly improved during the last decades. The focus is no longer solely on males, but also on how female competition and male mate choice shape ornamentation and other sexually selected traits in females. At the same time, the focus has shifted from documenting sexual selection to exploring variation and spatiotemporal dynamics of sexual selection, and their evolutionary consequences. Here, I review insights from a model system with exceptionally dynamic sexual selection, the two-spotted goby fish Gobiusculus flavescens. The species displays a complete reversal of sex roles over a 3-month breeding season. The reversal is driven by a dramatic change in the operational sex ratio, which is heavily male-biased at the start of the season and heavily female-biased late in the season. Early in the season, breeding-ready males outnumber mature females, causing males to be highly competitive, and leading to sexual selection on males. Late in the season, mating-ready females are in excess, engage more in courtship and aggression than males, and rarely reject mating opportunities. With typically many females simultaneously courting available males late in the season, males become selective and prefer more colorful females. This variable sexual selection regime likely explains why both male and female G. flavescens have ornamental colors. The G. flavescens model system reveals that sexual behavior and sexual selection can be astonishingly dynamic in response to short-term fluctuations in mating competition. Future work should explore whether sexual selection is equally dynamic on a spatial scale, and related spatiotemporal dynamics.
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Affiliation(s)
- Trond Amundsen
- Department of Biology, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
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21
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Karageorge KW, Wilson RR. An integrative mating system assessment of a nonmodel, economically important Pacific rockfish ( Sebastes melanops) reveals nonterritorial polygamy and conservation implications for a large species flock. Ecol Evol 2017; 7:11277-11291. [PMID: 29299300 PMCID: PMC5743636 DOI: 10.1002/ece3.3579] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 08/01/2017] [Accepted: 08/11/2017] [Indexed: 11/23/2022] Open
Abstract
Characterizing the mating systems of long-lived, economically important Pacific rockfishes comprising the viviparous Sebastes species flock is crucial for their conservation. However, direct assignment of mating success to sires is precluded by open, offshore populations and high female fecundity. We addressed this challenge by integrating paternity-assigned mating success of females with the adult sex ratio (ASR) of the population, male evolutionary responses to receptive females, and reproductive life history traits-in the framework of sexual selection theory-to assess the mating system of Sebastes melanops. Microsatellite parentage analysis of 17 pregnant females, 1,256 of their progeny, and 106 adults from the population yielded one to four sires per brood, a mean of two sires, and a female mate frequency distribution with a truncated normal (random) pattern. The 11 multiple paternity broods all contained higher median allele richness than the six single paternity broods (Wilcoxon test: W = 0, p < .001), despite similar levels of average heterozygosity. By sampling sperm and alleles from different males, polyandrous females gain opportunities to enhance their sperm supply and to lower the cost of mating with genetically incompatible males through reproductive compensation. A mean of two mates per mated female with a variance of one, an ASR = 1.2 females per male, and the expected population mean of 2.4 mates for mated males (and the estimated 35 unavailable sires), fits polygamous male mate frequency distributions that distinguish polygynandry and polyandrogyny mating systems, that is, variations of polygamy, but not polyandry. Inference for polygamy is consistent with weak premating sexual selection on males, expected in mid-water, schooling S. melanops, owing to polyandrous mating, moderately aggregated receptive females, an even ASR, and no territories and nests used for reproduction. Each of these characteristics facilitates more mating males and erodes conspicuous sexual dimorphism. Evaluation of male evolutionary responses of demersal congeners that express reproductively territorial behavior revealed they have more potential mechanisms for producing premating sexual selection, greater variation in reproductive success, and a reduced breeding effective population size of adults and annual effective size of a cohort, compared to S. melanops modeled with two mates per adult. Such divergence in behavior and mating system by territorial species may differentially lower their per capita birth rates, subsequent population growth, and slow their recovery from exploitation.
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Affiliation(s)
- Kurt W. Karageorge
- Department of Biological SciencesCalifornia State UniversityLong BeachCAUSA
| | - Raymond R. Wilson
- Department of Biological SciencesCalifornia State UniversityLong BeachCAUSA
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22
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Chandler CH. When and why does sex chromosome dosage compensation evolve? Ann N Y Acad Sci 2017; 1389:37-51. [DOI: 10.1111/nyas.13307] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 11/21/2016] [Accepted: 12/01/2016] [Indexed: 01/07/2023]
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23
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Flanagan SP, Rosenqvist G, Jones AG. Mate quality and the temporal dynamics of breeding in a sex-role-reversed pipefish, S. typhle. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2255-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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24
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Anthes N, Häderer IK, Michiels NK, Janicke T. Measuring and interpreting sexual selection metrics: evaluation and guidelines. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12707] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Nils Anthes
- Animal Evolutionary Ecology Group Institute for Evolution and Ecology University of Tübingen Auf der Morgenstelle 28 72076 Tübingen Germany
| | - Ines K. Häderer
- Animal Evolutionary Ecology Group Institute for Evolution and Ecology University of Tübingen Auf der Morgenstelle 28 72076 Tübingen Germany
| | - Nico K. Michiels
- Animal Evolutionary Ecology Group Institute for Evolution and Ecology University of Tübingen Auf der Morgenstelle 28 72076 Tübingen Germany
| | - Tim Janicke
- Centre d'Écologie Fonctionnelle et Évolutive UMR 5175 CNRS University of Montpellier 1919 Route de Mende 34293 Montpellier Cedex 05 France
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25
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Marie-Orleach L, Janicke T, Vizoso DB, David P, Schärer L. Quantifying episodes of sexual selection: Insights from a transparent worm with fluorescent sperm. Evolution 2016; 70:314-28. [PMID: 26787006 DOI: 10.1111/evo.12861] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 12/03/2015] [Accepted: 12/22/2015] [Indexed: 01/14/2023]
Abstract
Sexual selection operates through consecutive episodes of selection that ultimately contribute to the observed variance in reproductive success between individuals. Understanding the relative importance of these episodes is challenging, particularly because the relevant postcopulatory fitness components are often difficult to assess. Here, we investigate different episodes of sexual selection on the male sex function, by assessing how (precopulatory) mating success, and (postcopulatory) sperm-transfer efficiency and sperm-fertilizing efficiency contribute to male reproductive success. Specifically, we used a transgenic line of the transparent flatworm, Macrostomum lignano, which expresses green fluorescent protein (GFP) in all cell types, including sperm cells, enabling in vivo sperm tracking and paternity analysis. We found that a large proportion of variance in male reproductive success arose from the postcopulatory episodes. Moreover, we also quantified selection differentials on 10 morphological traits. Testis size and seminal vesicle size showed significant positive selection differentials, which were mainly due to selection on sperm-transfer efficiency. Overall, our results demonstrate that male reproductive success in M. lignano is not primarily limited by the number of matings achieved, but rather by the ability to convert matings into successful fertilizations, which is facilitated by producing many sperm.
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Affiliation(s)
- Lucas Marie-Orleach
- Zoological Institute, University of Basel, Basel, Switzerland. .,Centre for Biological Diversity, University of St Andrews, St Andrews, United Kingdom.
| | - Tim Janicke
- Zoological Institute, University of Basel, Basel, Switzerland.,Centre d'Écologie Fonctionnelle et Évolutive, Montpellier, France
| | - Dita B Vizoso
- Zoological Institute, University of Basel, Basel, Switzerland
| | - Patrice David
- Centre d'Écologie Fonctionnelle et Évolutive, Montpellier, France
| | - Lukas Schärer
- Zoological Institute, University of Basel, Basel, Switzerland
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26
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Janicke T, Häderer IK, Lajeunesse MJ, Anthes N. Darwinian sex roles confirmed across the animal kingdom. SCIENCE ADVANCES 2016; 2:e1500983. [PMID: 26933680 PMCID: PMC4758741 DOI: 10.1126/sciadv.1500983] [Citation(s) in RCA: 225] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/30/2015] [Indexed: 06/01/2023]
Abstract
Since Darwin's conception of sexual selection theory, scientists have struggled to identify the evolutionary forces underlying the pervasive differences between male and female behavior, morphology, and physiology. The Darwin-Bateman paradigm predicts that anisogamy imposes stronger sexual selection on males, which, in turn, drives the evolution of conventional sex roles in terms of female-biased parental care and male-biased sexual dimorphism. Although this paradigm forms the cornerstone of modern sexual selection theory, it still remains untested across the animal tree of life. This lack of evidence has promoted the rise of alternative hypotheses arguing that sex differences are entirely driven by environmental factors or chance. We demonstrate that, across the animal kingdom, sexual selection, as captured by standard Bateman metrics, is indeed stronger in males than in females and that it is evolutionarily tied to sex biases in parental care and sexual dimorphism. Our findings provide the first comprehensive evidence that Darwin's concept of conventional sex roles is accurate and refute recent criticism of sexual selection theory.
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Affiliation(s)
- Tim Janicke
- Centre d’Écologie Fonctionnelle et Évolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, École Pratique des Hautes Études, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Ines K. Häderer
- Animal Evolutionary Ecology Group, Institute for Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Marc J. Lajeunesse
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Nils Anthes
- Animal Evolutionary Ecology Group, Institute for Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
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27
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A rigorous comparison of sexual selection indexes via simulations of diverse mating systems. Proc Natl Acad Sci U S A 2016; 113:E300-8. [PMID: 26739567 DOI: 10.1073/pnas.1518067113] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sexual selection is a cornerstone of evolutionary theory, but measuring it has proved surprisingly difficult and controversial. Various proxy measures--e.g., the Bateman gradient and the opportunity for sexual selection--are widely used in empirical studies. However, we do not know how reliably these measures predict the strength of sexual selection across natural systems, and most perform poorly in theoretical worst-case scenarios. Here we provide a rigorous comparison of eight commonly used indexes of sexual selection. We simulated 500 biologically plausible mating systems, based on the templates of five well-studied species that cover a diverse range of reproductive life histories. We compared putative indexes to the actual strength of premating sexual selection, measured as the strength of selection on a simulated "mating trait." This method sidesteps a key weakness of empirical studies, which lack an appropriate yardstick against which proxy measures can be assessed. Our model predicts that, far from being useless, the best proxy measures reliably track the strength of sexual selection across biologically realistic scenarios. The maximum intensity of precopulatory sexual selection s'max (the Jones index) outperformed all other indexes and was highly correlated with the strength of sexual selection. In contrast, the Bateman gradient and the opportunity for sexual selection were poor predictors of sexual selection, despite their continuing popularity.
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28
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Landis SH, Sundin J, Rosenqvist G, Poirier M, Jørgensen GØ, Roth O. Female pipefish can detect the immune status of their mates. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-2004-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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29
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Furness AI, Morrison KR, Orr TJ, Arendt JD, Reznick DN. Reproductive mode and the shifting arenas of evolutionary conflict. Ann N Y Acad Sci 2015; 1360:75-100. [PMID: 26284738 DOI: 10.1111/nyas.12835] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/21/2015] [Accepted: 06/05/2015] [Indexed: 12/11/2022]
Abstract
In sexually reproducing organisms, the genetic interests of individuals are not perfectly aligned. Conflicts among family members are prevalent since interactions involve the transfer of limited resources between interdependent players. Intrafamilial conflict has traditionally been considered along three major axes: between the sexes, between parents and offspring, and between siblings. In these interactions, conflict is expected over traits in which the resulting phenotypic value is determined by multiple family members who have only partially overlapping fitness optima. We focus on four major categories of animal reproductive mode (broadcast spawning, egg laying, live bearing, and live bearing with matrotrophy) and identify the shared phenotypes or traits over which conflict is expected, and then review the empirical literature for evidence of their occurrence. Major transitions among reproductive mode, such as a shift from external to internal fertilization, an increase in egg-retention time, modifications of embryos and mothers for nutrient transfer, the evolution of postnatal parental care, and increased interaction with the kin network, mark key shifts that both change and expand the arenas in which conflict is played out.
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Affiliation(s)
- Andrew I Furness
- Department of Biology, University of California, Riverside, California.,Department of Ecology and Evolutionary Biology, University of California, Irvine, California
| | - Keenan R Morrison
- Department of Biology, University of California, Riverside, California
| | - Teri J Orr
- Department of Biology, University of California, Riverside, California.,Department of Biology, University of Massachusetts, Amherst, Massachusetts
| | - Jeff D Arendt
- Department of Biology, University of California, Riverside, California
| | - David N Reznick
- Department of Biology, University of California, Riverside, California
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30
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Blackburn GS, Maddison WP. Insights to the mating strategies of Habronattus americanus jumping spiders from natural behaviour and staged interactions in the wild. BEHAVIOUR 2015. [DOI: 10.1163/1568539x-00003273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We documented natural behaviour and staged intersexual interactions ofHabronattusamericanusjumping spiders in the wild in order to clarify three aspects of their mating strategies: (1) Do males invest more than females in locomotory mate search? (2) Do females exert strong mate choice? (3) Do direct contests occur among males? Males apparently invested heavily in mate search, travelling more than females yet eating nothing. Conversely, females frequently hunted and spent 10% of their time feeding. Females encountered one male per hour, likely affording them a high degree of choice among prospective mates. Accordingly, they promoted the termination of each interaction and ultimately rejected nearly all courting males. Male–male interactions were brief and did not feature direct antagonism. Our findings suggest that mate competition inH. americanusis characterized by male scramble competition for dispersed females, and that female mate choice may exert strong selection on male sexual display traits.
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Affiliation(s)
- Gwylim S. Blackburn
- Department of Zoology, University of British Columbia, 4200-6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
| | - Wayne P. Maddison
- Department of Zoology, University of British Columbia, 4200-6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
- Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
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31
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Relationships between pair formation, site fidelity and sex in a coral reef cardinalfish. Behav Processes 2014; 107:119-26. [DOI: 10.1016/j.beproc.2014.07.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 06/11/2014] [Accepted: 07/26/2014] [Indexed: 11/23/2022]
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32
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Collet JM, Dean RF, Worley K, Richardson DS, Pizzari T. The measure and significance of Bateman's principles. Proc Biol Sci 2014; 281:20132973. [PMID: 24648220 PMCID: PMC3973258 DOI: 10.1098/rspb.2013.2973] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/20/2014] [Indexed: 11/12/2022] Open
Abstract
Bateman's principles explain sex roles and sexual dimorphism through sex-specific variance in mating success, reproductive success and their relationships within sexes (Bateman gradients). Empirical tests of these principles, however, have come under intense scrutiny. Here, we experimentally show that in replicate groups of red junglefowl, Gallus gallus, mating and reproductive successes were more variable in males than in females, resulting in a steeper male Bateman gradient, consistent with Bateman's principles. However, we use novel quantitative techniques to reveal that current methods typically overestimate Bateman's principles because they (i) infer mating success indirectly from offspring parentage, and thus miss matings that fail to result in fertilization, and (ii) measure Bateman gradients through the univariate regression of reproductive over mating success, without considering the substantial influence of other components of male reproductive success, namely female fecundity and paternity share. We also find a significant female Bateman gradient but show that this likely emerges as spurious consequences of male preference for fecund females, emphasizing the need for experimental approaches to establish the causal relationship between reproductive and mating success. While providing qualitative support for Bateman's principles, our study demonstrates how current approaches can generate a misleading view of sex differences and roles.
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Affiliation(s)
- Julie M. Collet
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
- School of Biological Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
- Department of Genetics, Evolution and Environment, University College London, The Darwin Building, Gower Street, London WC1E 6BT, UK
| | - Rebecca F. Dean
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
- Department of Genetics, Evolution and Environment, University College London, The Darwin Building, Gower Street, London WC1E 6BT, UK
- Department of Evolutionary Biology, Uppsala University, Norbyvägen 18D, Uppsala 752 36, Sweden
| | - Kirsty Worley
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
- Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - David S. Richardson
- Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Tommaso Pizzari
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
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33
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Roth O, Sundin J, Berglund A, Rosenqvist G, Wegner KM. Male mate choice relies on major histocompatibility complex class I in a sex-role-reversed pipefish. J Evol Biol 2014; 27:929-38. [DOI: 10.1111/jeb.12365] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 03/05/2014] [Accepted: 03/06/2014] [Indexed: 11/29/2022]
Affiliation(s)
- O. Roth
- Evolutionary Ecology of Marine Fishes; GEOMAR Helmholtz Centre for Ocean Research Kiel; Kiel Germany
| | - J. Sundin
- Department of Animal Ecology; Evolutionary Biology Centre (EBC); Uppsala University; Uppsala Sweden
| | - A. Berglund
- Department of Animal Ecology; Evolutionary Biology Centre (EBC); Uppsala University; Uppsala Sweden
| | - G. Rosenqvist
- Department of Biology; Norwegian University of Science and Technology; Trondheim Norway
| | - K. M. Wegner
- Coastal Ecology; Alfred Wegener Institute-Helmholtz Centre for Polar and Marine Research; List Germany
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34
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Stockley P, Campbell A. Female competition and aggression: interdisciplinary perspectives. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130073. [PMID: 24167303 PMCID: PMC3826202 DOI: 10.1098/rstb.2013.0073] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This paper introduces a Theme Issue combining interdisciplinary perspectives in the study of female competition and aggression. Despite a history of being largely overlooked, evidence is now accumulating for the widespread evolutionary significance of female competition. Here, we provide a synthesis of contributions to this Theme Issue on humans and other vertebrates, and highlight directions for future research. Females compete for resources needed to survive and reproduce, and for preferred mates. Although female aggression takes diverse forms, under most circumstances relatively low-risk competitive strategies are favoured, most probably due to constraints of offspring production and care. In social species, dominance relationships and threats of punishment can resolve social conflict without resort to direct aggression, and coalitions or alliances may reduce risk of retaliation. Consistent with these trends, indirect aggression is a low cost but effective form of competition among young women. Costs are also minimized by flexibility in expression of competitive traits, with aggressive behaviour and competitive signalling tailored to social and ecological conditions. Future research on female competition and the proximate mediators of female aggression will be greatly enhanced by opportunities for interdisciplinary exchange, as evidenced by contributions to this Theme Issue.
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Affiliation(s)
- Paula Stockley
- Mammalian Behaviour and Evolution Group, Institute of Integrative Biology, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK
| | - Anne Campbell
- Science Laboratories, Department of Psychology, Durham University, Durham DH1 3LE, UK
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35
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Nakadera Y, Koene JM. Reproductive strategies in hermaphroditic gastropods: conceptual and empirical approaches. CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0272] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An individual optimizes its reproductive success by adopting a particular reproductive strategy. Studying the details of a reproductive strategy leads to an understanding of how sexual selection acts, as the former is the process via which the individual reproduces successfully. Hermaphroditic gastropods display a bewildering diversity of reproductive strategies, which may be due to their mode of gender expression, when compared with well-studied separate-sexed species. Extensive theoretical, observational, and experimental research has been conducted on this topic. However, despite our knowledge about the reproductive system of hermaphroditic gastropods, we still need to fill the gap between pre- and post-copulatory processes and reproductive success. Here, we review and propose conceptual and empirical approaches aimed at understanding reproductive strategies of hermaphroditic gastropods. In sum, our suggestions are (i) to focus on sex-biased traits, (ii) to take biologically reliable measurements at both the pre- and post-copulatory level that relate to reproductive success, and (iii) to examine the fitness consequences of biased sex allocation.
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Affiliation(s)
- Yumi Nakadera
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081HV, Amsterdam, the Netherlands
| | - Joris M. Koene
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081HV, Amsterdam, the Netherlands
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36
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Fritzsche K, Arnqvist G. HOMAGE TO BATEMAN: SEX ROLES PREDICT SEX DIFFERENCES IN SEXUAL SELECTION. Evolution 2013; 67:1926-36. [DOI: 10.1111/evo.12086] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 01/08/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Karoline Fritzsche
- Animal Ecology, Department of Ecology and Genetics; Evolutionary Biology Centre; Uppsala University; Norbyvägen 18D, SE-752 36; Uppsala Sweden
| | - Göran Arnqvist
- Animal Ecology, Department of Ecology and Genetics; Evolutionary Biology Centre; Uppsala University; Norbyvägen 18D, SE-752 36; Uppsala Sweden
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37
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Schärer L, Pen I. Sex allocation and investment into pre- and post-copulatory traits in simultaneous hermaphrodites: the role of polyandry and local sperm competition. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120052. [PMID: 23339243 PMCID: PMC3576586 DOI: 10.1098/rstb.2012.0052] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sex allocation theory predicts the optimal allocation to male and female reproduction in sexual organisms. In animals, most work on sex allocation has focused on species with separate sexes and our understanding of simultaneous hermaphrodites is patchier. Recent theory predicts that sex allocation in simultaneous hermaphrodites should strongly be affected by post-copulatory sexual selection, while the role of pre-copulatory sexual selection is much less clear. Here, we review sex allocation and sexual selection theory for simultaneous hermaphrodites, and identify several strong and potentially unwarranted assumptions. We then present a model that treats allocation to sexually selected traits as components of sex allocation and explore patterns of allocation when some of these assumptions are relaxed. For example, when investment into a male sexually selected trait leads to skews in sperm competition, causing local sperm competition, this is expected to lead to a reduced allocation to sperm production. We conclude that understanding the evolution of sex allocation in simultaneous hermaphrodites requires detailed knowledge of the different sexual selection processes and their relative importance. However, little is currently known quantitatively about sexual selection in simultaneous hermaphrodites, about what the underlying traits are, and about what drives and constrains their evolution. Future work should therefore aim at quantifying sexual selection and identifying the underlying traits along the pre- to post-copulatory axis.
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Affiliation(s)
- Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland.
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Abstract
We give a historic overview and critical perspective of polyandry in the context of sexual selection. Early approaches tended to obfuscate the fact that the total matings (copulations) by the two sexes is equal, neglecting female interests and that females often mate with (or receive ejaculates from) more than one male (polyandry). In recent years, we have gained much more insight into adaptive reasons for polyandry, particularly from the female perspective. However, costs and benefits of multiple mating are unlikely to be equal for males and females. These must be assessed for each partner at each potential mating between male i and female j, and will often be highly asymmetric. Interests of i and j may be in conflict, with (typically, ultimately because of primordial sex differences) i benefitting and j losing from mating, although theoretically the reverse can also obtain. Polyandry reduces the sex difference in Bateman gradients, and the probability of sexual conflict over mating by: (i) reducing the potential expected value of each mating to males in inverse proportion to the number of mates per female per clutch, and also often by (ii) increasing ejaculate costs through increased sperm allocation. It can nevertheless create conflict over fertilization and increase conflict over parental investment. The observed mean mating frequency for the population (and hence the degree of polyandry) is likely, at least in part, to reflect a resolution of sexual conflict. Immense diversity exists across and within taxa in the extent of polyandry, and views on its significance have changed radically, as we illustrate using avian polyandry as a case study. Despite recent criticisms, the contribution of the early pioneers of sexual selection, Darwin and Bateman, remains generally valid, and should not, therefore, be negated; as with much in science, pioneering advances are more often amplified and refined, rather than replaced with entirely new paradigms.
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Affiliation(s)
- Geoff A Parker
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
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Sanna D, Biagi F, Alaya HB, Maltagliati F, Addis A, Romero A, De Juan J, Quignard JP, Castelli A, Franzoi P, Torricelli P, Casu M, Carcupino M, Francalacci P. Mitochondrial DNA variability of the pipefish Syngnathus abaster. JOURNAL OF FISH BIOLOGY 2013; 82:856-876. [PMID: 23464548 DOI: 10.1111/jfb.12027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 11/15/2012] [Indexed: 06/01/2023]
Abstract
This study provides data on the genetic structuring of the pipefish Syngnathus abaster in the western Mediterranean and Adriatic Seas. A total of 109 specimens were collected in brackish-water biotopes. The control region and three other regions of the mitochondrial genome were analysed. The most relevant result was the high genetic structuring found by Bayesian inference (BI), maximum likelihood (ML) and network analyses, which were consistent in showing three well-separated clusters of S. abaster populations. Furthermore, BI and ML did not support the monophyly of the taxon S. abaster. These results suggest the occurrence of a species complex in the study area, whose differentiation may have occurred since the Pleistocene. The results also show a very high genetic variability at the inter-population level, with no shared haplotypes among sites. Evolutionary forces due to the fragmented nature of the brackish-water habitats may account for the high genetic divergence found among the groups and populations. Finally, although dispersal by rafting over long distances may occasionally occur, this study suggests linear stepping-stone model of colonization to be most likely. The complexity of the results obtained suggests that further studies are needed to elucidate the phylogeny of S. abaster.
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Affiliation(s)
- D Sanna
- Dipartimento di Scienze della Natura e del Territorio - Sezione di Zoologia, Archeozoologia e Genetica, Università di Sassari, Via Francesco Muroni 25, 07100, Sassari, Italy
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Kvarnemo C, Simmons LW. Polyandry as a mediator of sexual selection before and after mating. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120042. [PMID: 23339234 PMCID: PMC3576577 DOI: 10.1098/rstb.2012.0042] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The Darwin–Bateman paradigm recognizes competition among males for access to multiple mates as the main driver of sexual selection. Increasingly, however, females are also being found to benefit from multiple mating so that polyandry can generate competition among females for access to multiple males, and impose sexual selection on female traits that influence their mating success. Polyandry can reduce a male's ability to monopolize females, and thus weaken male focused sexual selection. Perhaps the most important effect of polyandry on males arises because of sperm competition and cryptic female choice. Polyandry favours increased male ejaculate expenditure that can affect sexual selection on males by reducing their potential reproductive rate. Moreover, sexual selection after mating can ameliorate or exaggerate sexual selection before mating. Currently, estimates of sexual selection intensity rely heavily on measures of male mating success, but polyandry now raises serious questions over the validity of such approaches. Future work must take into account both pre- and post-copulatory episodes of selection. A change in focus from the products of sexual selection expected in males, to less obvious traits in females, such as sensory perception, is likely to reveal a greater role of sexual selection in female evolution.
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Affiliation(s)
- Charlotta Kvarnemo
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
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Gowaty PA, Kim YK, Anderson WW. Mendel's law reveals fatal flaws in Bateman's 1948 study of mating and fitness. Fly (Austin) 2013; 7:28-38. [PMID: 23360967 PMCID: PMC3660748 DOI: 10.4161/fly.23505] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 12/09/2012] [Accepted: 01/04/2013] [Indexed: 11/19/2022] Open
Abstract
Bateman's experimental study of Drosophila melanogaster produced conclusions that are now part of the bedrock premises of modern sexual selection. Today it is the most cited experimental study in sexual selection, and famous as the first experimental demonstration of sex differences in the relationship between number of mates and relative reproductive success. We repeated the experimental methodology of the original to evaluate its reliability. The results indicate that Bateman's methodology of visible mutations to assign parentage and reproductive success to subject adults is significantly biased. When combined in offspring, the mutations decrease offspring survival, so that counts of mate number and reproductive success are mismeasured. Bateman's method overestimates the number of subjects with no mates and underestimates the number with one or more mates for both sexes. Here we discuss why Bateman's paper is important and present additional analyses of data from our monogamy trials. Monogamy trials can inform inferences about the force of sexual selection in populations because in monogamy trials male-male competition and female choice are absent. Monogamy trials also would have provided Bateman with an a priori test of the fit of his data to Mendel's laws, an unstated, but vital assumption of his methodology for assigning parentage from which he inferred the number of mates per individual subject and their reproductive success. Even under enforced monogamous mating, offspring frequencies of double mutant, single mutant and no mutant offspring were significantly different from Mendelian expectations proving that Bateman's method was inappropriate for answering the questions he posed. Double mutant offspring (those with a mutation from each parent) suffered significant inviability as did single mutant offspring whenever they inherited their mother's marker but the wild-type allele at their father's marker locus. These inviability effects produced two important inaccuracies in Bateman's results and conclusions. (1) Some matings that actually occurred were invisible and (2) reproductive success of some mothers was under-estimated. Both observations show that Bateman's conclusions about sex differences in number of mates and reproductive success were unwarranted, based on biased observations. We speculate about why Bateman's classic study remained without replication for so long, and we discuss why repetition almost 60 years after the original is still timely, necessary and critical to the scientific enterprise. We highlight overlooked alternative hypotheses to urge that modern tests of Bateman's conclusions go beyond confirmatory studies to test alternative hypotheses to explain the relationship between mate number and reproductive success.
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Affiliation(s)
- Patricia Adair Gowaty
- Department of Ecology and Evolutionary Biology; University of California, Los Angeles; Los Angeles, CA USA
- Institute of the Environment and Sustainability; University of California, Los Angeles; Los Angeles, CA USA
- Smithsonian Tropical Research Institute; Washington, DC USA
| | - Yong-Kyu Kim
- Department of Genetics; University of Georgia; Athens, GA USA
- Department of Biology; Emory University; Atlanta, GA USA
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Roth O, Klein V, Beemelmanns A, Scharsack JP, Reusch TBH. Male Pregnancy and Biparental Immune Priming. Am Nat 2012; 180:802-14. [DOI: 10.1086/668081] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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43
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Mobley KB, Jones AG. OVERCOMING STATISTICAL BIAS TO ESTIMATE GENETIC MATING SYSTEMS IN OPEN POPULATIONS: A COMPARISON OF BATEMAN'S PRINCIPLES BETWEEN THE SEXES IN A SEX-ROLE-REVERSED PIPEFISH. Evolution 2012; 67:646-60. [DOI: 10.1111/j.1558-5646.2012.01819.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kokko H, Klug H, Jennions MD. Unifying cornerstones of sexual selection: operational sex ratio, Bateman gradient and the scope for competitive investment. Ecol Lett 2012; 15:1340-1351. [PMID: 22925080 DOI: 10.1111/j.1461-0248.2012.01859.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/10/2012] [Accepted: 07/23/2012] [Indexed: 11/28/2022]
Abstract
What explains variation in the strength of sexual selection across species, populations or differences between the sexes? Here, we show that unifying two well-known lines of thinking provides the necessary conceptual framework to account for variation in sexual selection. The Bateman gradient and the operational sex ratio (OSR) are incomplete in complementary ways: the former describes the fitness gain per mating and the latter the potential difficulty of achieving it. We combine this insight with an analysis of the scope for sexually selected traits to spread despite naturally selected costs. We explain why the OSR sometimes does not affect the strength of sexual selection. An explanation of sexual selection becomes more logical when a long 'dry time' ('time out', recovery after mating due to e.g. parental care) is understood to reduce the expected time to the next mating when in the mating pool (i.e. available to mate again). This implies weaker selection to shorten the wait. An integrative view of sexual selection combines an understanding of the origin of OSR biases with how they are reflected in the Bateman gradient, and how this can produce selection for mate acquisition traits despite naturally selected costs.
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Affiliation(s)
- Hanna Kokko
- Centre of Excellence in Biological Interactions, Division of Ecology, Evolution & Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - Hope Klug
- Department of Biological & Environmental Sciences, University of Tennessee Chattanooga, 215 Holt Hall, Dept 2653, 615 McCallie Aven, Chattanooga, TN, 37403, USA
| | - Michael D Jennions
- Centre of Excellence in Biological Interactions, Division of Ecology, Evolution & Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
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Gerlach NM, McGlothlin JW, Parker PG, Ketterson ED. Reinterpreting Bateman gradients: multiple mating and selection in both sexes of a songbird species. Behav Ecol 2012. [DOI: 10.1093/beheco/ars077] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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No evidence of sexual selection in a repetition of Bateman's classic study of Drosophila melanogaster. Proc Natl Acad Sci U S A 2012; 109:11740-5. [PMID: 22689966 DOI: 10.1073/pnas.1207851109] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We are unique in reporting a repetition of Bateman [Bateman AJ (1948) Heredity (Edinb) 2:349-368] using his methods of parentage assignment, which linked sex differences in variance of reproductive success and variance in number of mates in small populations of Drosophila melanogaster. Using offspring phenotypes, we inferred who mated with whom and assigned offspring to parents. Like Bateman, we cultured adults expressing dramatic phenotypes, so that each adult was heterozygous-dominant at its unique marker locus but had only wild-type alleles at all other subjects' marker loci. Assuming no viability effects of parental markers on offspring, the frequencies of parental phenotypes in offspring follow mendelian expectations: one-quarter will be double-mutants who inherit the dominant gene from each parent, the offspring from which Bateman counted the number of mates per breeder; half of the offspring must be single mutants inheriting the dominant gene of one parent and the wild-type allele of the other parent; and one-quarter would inherit neither of their parent's marker mutations. Here we show that inviability of double-mutant offspring biased inferences of mate number and number of offspring on which rest inferences of sex differences in fitness variances. Bateman's method overestimated subjects with zero mates, underestimated subjects with one or more mates, and produced systematically biased estimates of offspring number by sex. Bateman's methodology mismeasured fitness variances that are the key variables of sexual selection.
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48
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Jones PH, Van Zant JL, Dobson FS. Variation in reproductive success of male and female Columbian ground squirrels (Urocitellus columbianus). CAN J ZOOL 2012. [DOI: 10.1139/z2012-042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The imbalanced reproductive success of polygynous mammals results in sexual selection on male traits like body size. Males and females might have more balanced reproductive success under polygynandry, where both sexes mate multiply. Using 4 years of microsatellite DNA analyses of paternity and known maternity, we investigated variation in reproductive success of Columbian ground squirrels, Urocitellus columbianus (Ord, 1815); a species with multiple mating by both sexes and multiple paternity of litters. We asked whether male reproductive success was more variable than that of females under this mating system. The overall percentage of confirmed paternity was 61.4% of 339 offspring. The mean rate of multiple paternity in litters with known fathers was 72.4% (n = 29 litters). Estimated mean reproductive success of males (10.27 offspring) was about thrice that of females (3.11 offspring). Even after this difference was taken into account statistically, males were about three times as variable in reproductive success as females (coefficients of variation = 77.84% and 26.74%, respectively). The Bateman gradient (regression slope of offspring production on number of successful mates) was significantly greater for males (βM = 1.44) than females (βF = 0.28). Thus, under a polygynandrous mating system, males exhibited greater variation in reproductive success than females.
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Affiliation(s)
- Philip H. Jones
- Department of Microbiology, College of Medicine, University of Iowa, Iowa City, IA 52246, USA
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA
| | - Jeffrey L. Van Zant
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA
- Department of Biology, Hillsdale College, 33 East College Street, Hillsdale, MI 49242, USA
| | - F. Stephen Dobson
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA
- Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique, 1919 Route de Mende, 34293 Montpellier CEDEX 5, France
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Collet J, Richardson DS, Worley K, Pizzari T. Sexual selection and the differential effect of polyandry. Proc Natl Acad Sci U S A 2012; 109:8641-5. [PMID: 22592795 PMCID: PMC3365207 DOI: 10.1073/pnas.1200219109] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In principle, widespread polyandry (female promiscuity) creates potential for sexual selection in males both before and after copulation. However, the way polyandry affects pre- and postcopulatory episodes of sexual selection remains little understood. Resolving this fundamental question has been difficult because it requires extensive information on mating behavior as well as paternity for the whole male population. Here we show that in replicate seminatural groups of red junglefowl, Gallus gallus, polyandry eroded variance in male mating success, which simultaneously weakened the overall intensity of sexual selection but increased the relative strength of postcopulatory episodes. We further illustrate the differential effect of polyandry on pre- and postcopulatory sexual selection by considering the case of male social status, a key determinant of male reproductive success in this species. In low-polyandry groups, however, status was strongly sexually selected before copulation because dominants mated with more females. In high-polyandry groups, sexual selection for status was weakened and largely restricted after copulation because dominants defended paternity by mating repeatedly with the same female. These results reveal polyandry as a potent and dynamic modulator of sexual selection episodes.
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Affiliation(s)
- Julie Collet
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - David S. Richardson
- Centre for Ecology, Evolution, and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Kirsty Worley
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom
- Centre for Ecology, Evolution, and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Tommaso Pizzari
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom
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Bergeron P, Montiglio PO, Réale D, Humphries MM, Garant D. Bateman gradients in a promiscuous mating system. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1364-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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