1
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Sharda S, Hollis B, Kawecki TJ. Sex ratio affects sexual selection against mutant alleles in a locus-specific way. Behav Ecol 2024; 35:arad110. [PMID: 38162691 PMCID: PMC10756055 DOI: 10.1093/beheco/arad110] [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: 08/07/2023] [Revised: 10/11/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024] Open
Abstract
Higher male:female operational sex ratio (OSR) is often assumed to lead to stronger sexual selection on males. Yet, this premise has been directly tested by very few studies, with mixed outcomes. We investigated how OSR affects the strength of sexual selection against two deleterious alleles, a natural ebony mutant and a transgenic GFP insertion, in Drosophila melanogaster. To this end, we estimated the relative paternity share of homozygous mutant males competing against wild-type males under different OSRs (1:2, 1:1, 2:1). We also manipulated the mating pool density (18, 36, or 54 individuals) and assessed paternity over three consecutive days, during which the nature of sexual interaction changed. The strength of sexual selection against the ebony mutant increased with OSR, became weaker after the first day, and was little affected by density. In contrast, sexual selection against the GFP transgene was markedly affected by density: at the highest density, it increased with OSR, but at lower densities, it was strongest at 1:1 OSR, remaining strong throughout the experiment. Thus, while OSR can strongly affect the strength of sexual selection against "bad genes," it does not necessarily increase monotonically with male:female OSR. Furthermore, the pattern of relationship between OSR and the strength of sexual selection can be locus-specific, likely reflecting the specific phenotypic effects of the mutation.
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Affiliation(s)
- Sakshi Sharda
- Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland and
| | - Brian Hollis
- Department of Biological Sciences, University of South Carolina, 715 Sumter St., Columbia SC 29208, USA
| | - Tadeusz J Kawecki
- Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland and
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2
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Daniel DK, Bhat A. Correlations begin at home: drivers of co-occurrence patterns in personality and cognitive ability in wild populations of zebrafish. Anim Cogn 2023:10.1007/s10071-023-01787-w. [PMID: 37248284 DOI: 10.1007/s10071-023-01787-w] [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: 07/17/2022] [Revised: 04/16/2023] [Accepted: 05/11/2023] [Indexed: 05/31/2023]
Abstract
Aquatic habitats are extremely dynamic, with constantly changing ecological factors, which has now been exacerbated due to human-induced rapid environmental change. In such variable environments, it becomes essential to understand how personality and cognition in organisms affect the adaptability of individuals to different habitat conditions. To test this, we studied how personality-related traits as well as cognitive ability differ between populations of wild-caught zebrafish (Danio rerio) from habitats that differed in various environmental factors. We measured emergence into a novel environment as an indicator of boldness, and performance in a spatial task inferred from feeding latencies in a maze over repeated trials to assess learning and memory, as an indicator of cognitive ability. We found that personality affects cognition and although bolder fish are better learners, they show poorer retention of memory across populations. Although personality and cognitive ability varied between habitats, the patterns of their correlations remained similar within each population. However, the individual traits (such as sex and size) that were drivers of personality and cognition differed between the habitats, suggesting that not only do behavioral traits vary between populations, but also the factors that are important in determining them. Personality and cognitive ability and the correlations between these traits determine how well an organism performs in its habitat, as well as how likely it is to find new habitats and adapt to them. Studying these across wild zebrafish populations helps predict performance efficiencies among individuals and also explains how fish adapt to extremely dynamic environments that can lead to variation in behavioral traits and correlations between them. This study not only sheds light on the drivers of interindividual variation and co-occurrence patterns of personality and cognition, but also individual and population factors that might have an effect on them.
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Affiliation(s)
- Danita K Daniel
- Department of Biological Science, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, 741246, India
| | - Anuradha Bhat
- Department of Biological Science, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, 741246, India.
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3
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McDonald GC. The impact of small groups on pre- and postcopulatory sexual selection in polyandrous populations. Ecol Evol 2023; 13:e10057. [PMID: 37153025 PMCID: PMC10154804 DOI: 10.1002/ece3.10057] [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: 11/28/2022] [Revised: 04/08/2023] [Accepted: 04/19/2023] [Indexed: 05/09/2023] Open
Abstract
Sexual selection is a key evolutionary force but varies widely between populations. Two key factors that influence sexual selection are the extent to which females copulate with multiple males (polyandry) and variation in the social environment. Increasing research demonstrates populations are structured by complex socio-sexual networks, and the structure of these networks can influence sexual selection by shaping the relationship between male precopulatory mating success and the intensity of postcopulatory competition. However, comparatively less attention has been dedicated to the influence of group structure on sexual selection and how differences in the size of groups may impact on the relative force of pre- and postcopulatory sexual selection in polyandrous populations. The presence of groups (i.e., group structure) and the size of groups varies widely in nature and forms an implicit part of much experimental sexual selection research under laboratory conditions. Here I use simulations of mating competition within populations that vary in the size of groups they contain, to show that variation in group size, and in particular small groups, can influence sexual selection. Specifically, I show that null expectations for the operation of pre- and postcopulatory sexual selection is governed by the size of groups within populations because smaller group sizes constrain the structure of sexual networks leading to reinforcing episodes of pre- and postcopulatory sexual selection. Given broad variation in group structure in nature and the tendency for experimental sexual selection research to study replicate small groups, these effects have implications for our understanding of the operation of sexual selection in polyandrous populations.
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Affiliation(s)
- Grant C. McDonald
- Department of EcologyUniversity of Veterinary Medicine BudapestBudapestHungary
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4
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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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5
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Chuard PJC, Grant JWA, Brown GE. Mating competition and adult sex ratio in wild Trinidadian guppies. Behav Ecol 2022. [DOI: 10.1093/beheco/arac058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Most experimental tests of mating systems theory have been conducted in the laboratory, using operational sex ratios (ratio of ready-to-mate male to ready-to-mate female) that are often not representative of natural conditions. Here, we first measured the range of adult sex ratio (proportion of adult males to adult females; ASR) in two populations of Trinidadian guppies (Poecilia reticulata) differing in ambient predation risk (high vs. low). We then explored, under semi-wild conditions, the effect of ASR (i.e., 0.17, 0.50, 0.83) on mating competition patterns in these populations. ASR in the wild was female-biased and did not significantly differ between the two populations. The range of ASR in our experiment was representative of natural ASRs. As expected, we observed an increase in intrasexual aggression rates in both sexes as the relative abundance of competitors increased. In support of the risky competition hypothesis, all measured behaviors had lower rates in a high versus low predation-risk population, likely due to the costs of predation. In terms of mating tactics, a male-biased ASR did not lead males to favor forced mating over courtship, indicating that males did not compensate for the cost of competition by switching to a less costly alternative mating tactic. Overall, this study highlights the need for field experiments using natural ranges of ASRs to test the validity of mating systems theory in a more complex, ecologically relevant context.
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Affiliation(s)
- Pierre J C Chuard
- Department of Geography, Planning and Environment, Concordia University , Montréal, QC , Canada
| | - James W A Grant
- Department of Biology, Concordia University , Montréal, QC , Canada
| | - Grant E Brown
- Department of Biology, Concordia University , Montréal, QC , Canada
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6
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LaDage LD, Yu T, Zani PA. Higher Rate of Male Sexual Displays Correlates with Larger Ventral Posterior Amygdala Volume and Neuron Soma Volume in Wild-Caught Common Side-Blotched Lizards, Uta stansburiana. BRAIN, BEHAVIOR AND EVOLUTION 2022; 97:298-308. [PMID: 35537399 DOI: 10.1159/000524915] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 04/28/2022] [Indexed: 06/14/2023]
Abstract
Several areas of the vertebrate brain are involved in facilitating and inhibiting the production of sexual behaviors and displays. In the laboratory, a higher rate of sexual displays is correlated with a larger ventral posterior amygdala (VPA), an area of the brain involved in the expression of sexual display behaviors, as well as larger VPA neuronal somas. However, it remains unclear if individuals in the field reflect similar patterns, as there are likely many more selective pressures in the field that may also modulate the VPA architecture. In this study, we examined variation in VPA volume and neuron soma volume in wild-caught common side-blotched lizards (Uta stansburiana) from two different populations. In a population from Nevada, males experience high predation pressure and have decreased sexual display rates during the breeding season, whereas a population in Oregon has lower levels of predation and higher rates of male sexual displays. We found that wild-caught males from the population with lower display rates also exhibited decreased VPA volume and VPA neuron cell soma volume, which may suggest that decreased display rate, possibly due to increased predation rate, covaries with VPA attributes.
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Affiliation(s)
- Lara D LaDage
- Division of Mathematics & Natural Sciences, Penn State Altoona, Altoona, Pennsylvania, USA
| | - Tracy Yu
- Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Peter A Zani
- Department of Biology, University of Wisconsin - Stevens Point, Stevens Point, Wisconsin, USA
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7
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Watts J, Hebets EA, Tenhumberg B. Mate sampling behavior determines the density-dependence of sexual selection. Am Nat 2022; 200:467-485. [DOI: 10.1086/720716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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8
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Morales-Mata JI, Potti J, Camacho C, Martínez-Padilla J, Canal D. Phenotypic selection on an ornamental trait is not modulated by breeding density in a pied flycatcher population. J Evol Biol 2022; 35:610-620. [PMID: 35293060 PMCID: PMC9311403 DOI: 10.1111/jeb.13993] [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: 05/14/2021] [Revised: 01/25/2022] [Accepted: 02/08/2022] [Indexed: 11/29/2022]
Abstract
Most studies of phenotypic selection in the wild have focussed on morphological and life‐history traits and looked at abiotic (climatic) variation as the main driver of selection. Consequently, our knowledge of the effects of biotic environmental variation on phenotypic selection on sexual traits is scarce. Population density can be considered a proxy for the intensity of intrasexual and intersexual competition and could therefore be a key factor influencing the covariation between individual fitness and the expression of sexual traits. Here, we used an individual‐based data set from a population of pied flycatchers (Ficedula hypoleuca) monitored over 24 years to analyze the effect of breeding density on phenotypic selection on dorsal plumage colouration, a heritable and sexually selected ornament in males of this species. Using the number of recruits as a fitness proxy, our results showed overall stabilizing selection on male dorsal colouration, with intermediate phenotypes being favoured over extremely dark and dull individuals. However, our results did not support the hypothesis that breeding density mediates phenotypic selection on this sexual trait. We discuss the possible role of other biotic factors influencing selection on ornamental plumage.
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Affiliation(s)
| | - Jaime Potti
- Department of Evolutionary Ecology, Estación Biológica de Doñana (CSIC), Seville, Spain
| | - Carlos Camacho
- Department of Biological Conservation and Ecosystem Restoration, Pyrenean Institute of Ecology (IPE-CSIC), Jaca, Spain
| | - Jesús Martínez-Padilla
- Department of Biological Conservation and Ecosystem Restoration, Pyrenean Institute of Ecology (IPE-CSIC), Jaca, Spain
| | - David Canal
- Centre for Ecological Research, Institute of Ecology and Botany, Vácrátót, Hungary
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9
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Driscoll JG, Alo FM, Paoli A, Weladji RB, Holand Ø, Kumpula J, Soveri T. Influence of operational sex ratio and male age on mating competition intensity in reindeer (Rangifer tarandus). ETHOL ECOL EVOL 2022. [DOI: 10.1080/03949370.2021.1975997] [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]
Affiliation(s)
- Jeffrey G. Driscoll
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Franco M. Alo
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Amélie Paoli
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Robert B. Weladji
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Øystein Holand
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, Ås 1432, Norway
| | - Jouko Kumpula
- Natural Resources Institute of Finland (Luke), Ecosystems and Ecology, Saarikoskentie 99910, Finland
| | - Timo Soveri
- Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Paroninkuja 20, 04920 Saarentaus, Finland
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10
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Driscoll JG, Alo FM, Paoli A, Weladji RB, Holand Ø, Kumpula J, Soveri T. Influence of operational sex ratio and male age on mating competition intensity in reindeer ( Rangifer tarandus). ETHOL ECOL EVOL 2021. [DOI: 10.1080/03949370.2021.1989054] [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]
Affiliation(s)
- Jeffrey G. Driscoll
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Franco M. Alo
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Amélie Paoli
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Robert B. Weladji
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B1R6, Canada
| | - Øystein Holand
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Jouko Kumpula
- Ecosystems and Ecology, Natural Resources Institute of Finland (Luke), 99910, Finland
| | - Timo Soveri
- Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, Helsinki, Finland
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11
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Kim B, Moran NP, Reinhold K, Sánchez-Tójar A. Male size and reproductive performance in three species of livebearing fishes (Gambusia spp.): A systematic review and meta-analysis. J Anim Ecol 2021; 90:2431-2445. [PMID: 34231219 DOI: 10.1111/1365-2656.13554] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/05/2021] [Indexed: 11/27/2022]
Abstract
The genus Gambusia represents approximately 45 species of polyandrous livebearing fishes with reversed sexual size dimorphism (i.e. males smaller than females) and with copulation predominantly via male coercion. Male body size has been suggested as an important sexually selected trait, but despite abundant research, evidence for sexual selection on male body size in this genus is mixed. Studies have found that large males have an advantage in both male-male competition and female choice, but that small males perform sneaky copulations better and at higher frequency and thus may sire more offspring in this coercive mating system. Here, we synthesized this inconsistent body of evidence using pre-registered methods and hypotheses. We performed a systematic review and meta-analysis of summary and primary (raw) data combining both published (n = 19 studies, k = 106 effect sizes) and unpublished effect sizes (n = 17, k = 242) to test whether there is overall selection on male body size across studies in Gambusia. We also tested several specific hypotheses to understand the sources of heterogeneity across effects. Meta-analysis revealed an overall positive correlation between male size and reproductive performance (r = 0.23, 95% confidence interval: 0.10-0.35, n = 36, k = 348, 4,514 males, three Gambusia species). Despite high heterogeneity, the large-male advantage appeared robust across all measures studied (i.e. female choice, mating success, paternity, sperm quantity and quality), and was considerably larger for female choice (r = 0.43, 95% confidence interval: 0.28-0.59, n = 14, k = 43). Meta-regressions found several important factors explaining heterogeneity across effects, including type of sperm characteristic, male-to-female ratio, female reproductive status and environmental conditions. We found evidence of publication bias; however, its influence on our estimates was attenuated by including a substantial amount of unpublished effects, highlighting the importance of open primary data for more accurate meta-analytic estimates. In addition to positive selection on male size, our study suggests that we need to rethink the role and form of sexual selection in Gambusia and, more broadly, to consider the ecological factors that affect reproductive behaviour in livebearing fishes.
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Affiliation(s)
- Bora Kim
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| | - Nicholas Patrick Moran
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany.,Centre for Ocean Life DTU-Aqua, Technical University of Denmark, Lyngby, Denmark
| | - Klaus Reinhold
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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12
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Dougherty LR. Designing mate choice experiments. Biol Rev Camb Philos Soc 2020; 95:759-781. [PMID: 32022418 DOI: 10.1111/brv.12586] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 01/22/2020] [Accepted: 01/23/2020] [Indexed: 12/31/2022]
Abstract
The important role that mate choice plays in the lives of animals is matched by the large and active research field dedicated to studying it. Researchers work on a wide range of species and behaviours, and so the experimental approaches used to measure animal mate choice are highly variable. Importantly, these differences are often not purely cosmetic; they can strongly influence the measurement of choice, for example by varying the behaviour of animals during tests, the aspects of choice actually measured, and statistical power. Consideration of these effects are important when comparing results among studies using different types of test, or when using laboratory results to predict animal behaviour in natural populations. However, these effects have been underappreciated by the mate choice literature to date. I focus on five key experimental considerations that may influence choice: (i) should mating be allowed to occur, or should a proxy behavioural measure of preference be used instead? (ii) Should subjects be given a choice of options? (iii) Should each subject be tested more than once, either with the same or different stimuli? (iv) When given a choice, how many options should the subject choose between? (v) What form should the experimental stimuli take? I discuss the practical advantages and disadvantages of common experimental approaches, and how they may influence the measurement of mate choice in systematic ways. Different approaches often influence the ability of animals to perceive and compare stimuli presented during tests, or the perceived costs and benefits of being choosy. Given that variation in the design of mate choice experiments is likely unavoidable, I emphasise that there is no single 'correct' approach to measuring choice across species, although ecological relevance is crucial if the aim is to understand how choice acts in natural populations. I also highlight the need for quantitative estimates of the sizes of potentially important effects, without which we cannot make informed design decisions.
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Affiliation(s)
- Liam R Dougherty
- Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7RB, UK
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13
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House CM, Rapkin J, Hunt J, Hosken DJ. Operational sex ratio and density predict the potential for sexual selection in the broad-horned beetle. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.03.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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14
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Head ML, Kahn AT, Henshaw JM, Keogh JS, Jennions MD. Sexual selection on male body size, genital length and heterozygosity: Consistency across habitats and social settings. J Anim Ecol 2017; 86:1458-1468. [PMID: 28815592 DOI: 10.1111/1365-2656.12742] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/30/2017] [Indexed: 12/22/2022]
Abstract
Spatial and temporal variation in environmental factors and the social setting can help to maintain genetic variation in sexually selected traits if it affects the strength of directional selection. A key social parameter which affects the intensity of, and sometimes predicts the response to, mating competition is the operational sex ratio (OSR; ratio of receptive males to females). How the OSR affects selection for specific male traits is poorly understood. It is also unclear how sexual selection is affected by interactions between the OSR and environmental factors, such as habitat complexity, that alter key male-female interactions such as mate encounter rates. Here, we experimentally manipulated the OSR and habitat complexity and quantified sexual selection on male mosquitofish (Gambusia holbrooki) by directly measuring male reproductive success (i.e. paternity). We show that despite a more equitable sharing of paternity (i.e. higher levels of multiple paternity) under a male-biased OSR, selection on focal male traits was unaffected by the OSR or habitat complexity. Instead, sexual selection consistently, and significantly, favoured smaller bodied males, males with higher genome wide heterozygosity (based on >3,000 SNP markers) and males with a relatively long gonopodium (intromittent organ). Our results show that sexual selection on male body size, relative genital size and heterozygosity in this system is consistent across environments that vary in ecological parameters that are expected to influence mate encounter rates.
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Affiliation(s)
- Megan L Head
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
| | - Andrew T Kahn
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
| | - Jonathan M Henshaw
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
| | - J Scott Keogh
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
| | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
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15
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Gasparini C, Dosselli R, Evans JP. Sperm storage by males causes changes in sperm phenotype and influences the reproductive fitness of males and their sons. Evol Lett 2017; 1:16-25. [PMID: 30283635 PMCID: PMC6121797 DOI: 10.1002/evl3.2] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/20/2017] [Accepted: 01/25/2017] [Indexed: 01/26/2023] Open
Abstract
Recent studies suggest that environmentally induced effects on sperm phenotype can influence offspring phenotype beyond the classic Mendelian inheritance mechanism. However, establishing whether such effects are conveyed purely through ejaculates, independently of maternal environmental effects, remains a significant challenge. Here, we assess whether environmentally induced effects on sperm phenotype affects male reproductive success and offspring fitness. We experimentally manipulated the duration of sperm storage by males, and thus sperm age, in the internally fertilizing fish Poecilia reticulata. We first confirm that sperm ageing influences sperm quality and consequently males reproductive success. Specifically, we show that aged sperm exhibit impaired velocity and are competitively inferior to fresh sperm when ejaculates compete to fertilize eggs. We then used homospermic (noncompetitive) artificial insemination to inseminate females with old or fresh sperm and found that male offspring arising from fertilizations by experimentally aged sperm suffered consistently impaired sperm quality when just sexually mature (four months old) and subsequently as adults (13 months old). Although we have yet to determine whether these effects have a genetic or epigenetic basis, our analyses provide evidence that environmentally induced variation in sperm phenotype constitutes an important source of variation in male reproductive fitness that has far reaching implications for offspring fitness.
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Affiliation(s)
- Clelia Gasparini
- Centre for Evolutionary Biology, School of Biological Sciences (M092) University of Western Australia Crawley 6009 Australia
| | - Ryan Dosselli
- Centre for Evolutionary Biology, School of Biological Sciences (M092) University of Western Australia Crawley 6009 Australia.,CIBER, ARC Centre of Excellence in Plant Energy Biology University of Western Australia Crawley 6009 Australia
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences (M092) University of Western Australia Crawley 6009 Australia
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16
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Scordato ES. Geographical variation in male territory defence strategies in an avian ring species. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.01.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Martin AM, Festa-Bianchet M, Coltman DW, Pelletier F. Demographic drivers of age-dependent sexual selection. J Evol Biol 2016; 29:1437-46. [PMID: 27090379 DOI: 10.1111/jeb.12883] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 03/21/2016] [Accepted: 04/11/2016] [Indexed: 01/21/2023]
Abstract
Sexual selection has a critical role in evolution, and it is fundamental to identify what ecological factors drive its variation. Disentangling the ecological correlates of sexual selection over the long term, however, is challenging and has rarely been done in nature. We sought to assess how demographic changes influenced the intensity, direction and form of sexual selection and whether selective pressures varied with age. We tested whether breeder sex ratio, number of competitors and age structure influenced selection differentials on horn length of wild bighorn rams (Ovis canadensis) of different age classes on Ram Mountain, Alberta. We used 21 years of data including a detailed pedigree, demographic parameters and repeated morphological measurements. Sexual selection on horn length of males of all ages was directional and positive. Selection intensity increased with the number of competitors, reflecting male-male encounter rate during the rut, but was independent of breeder sex ratio or age structure. This result can also be linked to changes in population size because the number of competitors was highly correlated to total number of sheep. This demographic effect likely arises from age-dependent mating tactics. Males aged 2-4 years are weakly competitive and experienced stronger sexual selection as they accounted for a greater proportion of all males. Selection experienced by mature males appeared independent of demography. Our study provides a rare description of the demographic determinants of sexual selection in nature.
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Affiliation(s)
- A M Martin
- Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - M Festa-Bianchet
- Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - D W Coltman
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - F Pelletier
- Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada.,Canada Research Chair in Evolutionary Demography and Conservation, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
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18
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Hayes CL, Callander S, Booksmythe I, Jennions MD, Backwell PRY. Mate choice and the operational sex ratio: an experimental test with robotic crabs. J Evol Biol 2016; 29:1455-61. [DOI: 10.1111/jeb.12884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 11/28/2022]
Affiliation(s)
- C. L. Hayes
- Evolution, Ecology & Genetics; Research School of Biology; The Australian National University; Canberra ACT Australia
| | - S. Callander
- Evolution, Ecology & Genetics; Research School of Biology; The Australian National University; Canberra ACT Australia
| | - I. Booksmythe
- Evolution, Ecology & Genetics; Research School of Biology; The Australian National University; Canberra ACT Australia
| | - M. D. Jennions
- Evolution, Ecology & Genetics; Research School of Biology; The Australian National University; Canberra ACT Australia
| | - P. R. Y. Backwell
- Evolution, Ecology & Genetics; Research School of Biology; The Australian National University; Canberra ACT Australia
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19
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Head ML, Vega-Trejo R, Jacomb F, Jennions MD. Predictors of male insemination success in the mosquitofish (Gambusia holbrooki). Ecol Evol 2015; 5:4999-5006. [PMID: 26640677 PMCID: PMC4662323 DOI: 10.1002/ece3.1775] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 09/20/2015] [Indexed: 12/03/2022] Open
Abstract
Identifying targets of selection is key to understanding the evolution of sexually selected behavioral and morphological traits. Many animals have coercive mating, yet little is known about whether and how mate choice operates when these are the dominant mating tactic. Here, we use multivariate selection analysis to examine the direction and shape of selection on male insemination success in the mosquitofish (Gambusia holbrooki). We found direct selection on only one of five measured traits, but correlational selection involving all five traits. Larger males with longer gonopodia and with intermediate sperm counts were more likely to inseminate females than smaller males with shorter gonopodia and extreme sperm counts. Our results highlight the need to investigate sexual selection using a multivariate framework even in species that lack complex sexual signals. Further, female choice appears to be important in driving the evolution of male sexual traits in this species where sexual coercion is the dominant mating tactic.
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Affiliation(s)
- Megan L Head
- Division of Evolution, Ecology and Genetics Research School of Biology Australian National University Acton Canberra Australian Capital Territory 0200 Australia
| | - Regina Vega-Trejo
- Division of Evolution, Ecology and Genetics Research School of Biology Australian National University Acton Canberra Australian Capital Territory 0200 Australia
| | - Frances Jacomb
- Division of Evolution, Ecology and Genetics Research School of Biology Australian National University Acton Canberra Australian Capital Territory 0200 Australia
| | - Michael D Jennions
- Division of Evolution, Ecology and Genetics Research School of Biology Australian National University Acton Canberra Australian Capital Territory 0200 Australia
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20
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Holveck MJ, Gauthier AL, Nieberding CM. Dense, small and male-biased cages exacerbate male–male competition and reduce female choosiness in Bicyclus anynana. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.03.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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York JR, Baird TA. Testing the adaptive significance of sex-specific mating tactics in collared lizards (Crotaphytus collaris). Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12514] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Joshua R. York
- Department of Biology; University of Oklahoma; Norman OK 73019 USA
| | - Troy A. Baird
- Department of Biology; University of Central Oklahoma; Edmond OK 73034 USA
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22
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The effect of social environment on alternative mating tactics in male Endler's guppy, Poecilia wingei. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2013.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Rios Moura R, Peixoto PEC. The effect of operational sex ratio on the opportunity for sexual selection: a meta-analysis. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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24
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Aronsen T, Berglund A, Mobley KB, Ratikainen II, Rosenqvist G. SEX RATIO AND DENSITY AFFECT SEXUAL SELECTION IN A SEX-ROLE REVERSED FISH. Evolution 2013; 67:3243-57. [DOI: 10.1111/evo.12201] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 06/13/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Tonje Aronsen
- Department of Biology, Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; NO-7491 Trondheim Norway
| | - Anders Berglund
- Department of Ecology and Genetics/Animal Ecology; Uppsala University; SE-752 36 Uppsala Sweden
| | - Kenyon B. Mobley
- Department of Evolutionary Ecology; Max Planck Institute for Evolutionary Biology; 24306 Plön Germany
| | - Irja I. Ratikainen
- Department of Biology, Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; NO-7491 Trondheim Norway
| | - Gunilla Rosenqvist
- Department of Biology, Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; NO-7491 Trondheim Norway
- University of Gotland; SE-621 67 Visby Sweden
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25
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Wacker S, Mobley K, Forsgren E, Myhre LC, de Jong K, Amundsen T. OPERATIONAL SEX RATIO BUT NOT DENSITY AFFECTS SEXUAL SELECTION IN A FISH. Evolution 2013; 67:1937-49. [DOI: 10.1111/evo.12092] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 01/24/2013] [Indexed: 01/27/2023]
Affiliation(s)
- Sebastian Wacker
- Department of Biology; Norwegian University of Science and Technology; 7491 Trondheim Norway
| | - Kenyon Mobley
- Department of Biology; Norwegian University of Science and Technology; 7491 Trondheim Norway
- Max Planck Institute of Evolutionary Biology; 24306 Plön Germany
| | | | - Lise Cats Myhre
- Department of Biology; Norwegian University of Science and Technology; 7491 Trondheim Norway
| | - Karen de Jong
- Department of Biology; Norwegian University of Science and Technology; 7491 Trondheim Norway
| | - Trond Amundsen
- Department of Biology; Norwegian University of Science and Technology; 7491 Trondheim Norway
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26
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Aronsen T, Mobley K, Berglund A, Sundin J, Billing A, Rosenqvist G. The operational sex ratio and density influence spatial relationships between breeding pipefish. Behav Ecol 2013. [DOI: 10.1093/beheco/art019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Janowitz SA, Fischer K. Polyandry inBicyclus anynanaButterflies Results from Sexual Conflict over Mating. Ethology 2012. [DOI: 10.1111/eth.12017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Susann A. Janowitz
- Zoological Institute and Museum; University of Greifswald; Greifswald; Germany
| | - Klaus Fischer
- Zoological Institute and Museum; University of Greifswald; Greifswald; Germany
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28
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Ryder TB, Fleischer RC, Shriver WG, Marra PP. The ecological-evolutionary interplay: density-dependent sexual selection in a migratory songbird. Ecol Evol 2012; 2:976-87. [PMID: 22837842 PMCID: PMC3399163 DOI: 10.1002/ece3.254] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 03/02/2012] [Accepted: 03/07/2012] [Indexed: 12/02/2022] Open
Abstract
Little is understood about how environmental heterogeneity influences the spatial dynamics of sexual selection. Within human-dominated systems, habitat modification creates environmental heterogeneity that could influence the adaptive value of individual phenotypes. Here, we used the gray catbird to examine if the ecological conditions experienced in the suburban matrix (SM) and embedded suburban parks (SP) influence reproductive strategies and the strength of sexual selection. Our results show that these habitats varied in a key ecological factor, breeding density. Moreover, this ecological factor was closely tied to reproductive strategies such that local breeding density predicted the probability that a nest would contain extra-pair offspring. Partitioning reproductive variance showed that while within-pair success was more important in both habitats, extra-pair success increased the opportunity for sexual selection by 39% at higher breeding densities. Body size was a strong predictor of relative reproductive success and was under directional selection in both habitats. Importantly, our results show that the strength of sexual selection did not differ among habitats at the landscape scale but rather that fine-scale variation in an ecological factor, breeding density, influenced sexual selection on male phenotypes. Here, we document density-dependent sexual selection in a migratory bird and hypothesize that coarse-scale environmental heterogeneity, in this case generated by anthropogenic habitat modification, changed the fine-scale ecological conditions that drove the spatial dynamics of sexual selection.
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29
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de Jong K, Forsgren E, Sandvik H, Amundsen T. Measuring mating competition correctly: available evidence supports operational sex ratio theory. Behav Ecol 2012. [DOI: 10.1093/beheco/ars094] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AbstractCentral to sexual selection theory is the question of when individuals should compete for mates. Theory predicts that the sex ratio of ready-to-mate individuals (operational sex ratio; OSR) affects male and female mating competition. In accordance with this, the strength of mating competition, measured by agonistic behaviors and courtship displays, has been found to co-vary with the OSR in field populations of several species. However, laboratory experiments have often produced results that seemingly contradict OSR theory, especially for courtship behavior. We argue that this may be because experiments typically measure frequencies of competitive behaviors. Frequencies of courtship and agonistic behavior are not only affected by the level of mating competition, but also by the number of potential mates or competitors encountered. In contrast, the propensity to behave competitively at a given encounter represents a behavioral response, and thus directly reflects mating competition. We show in 2 simple models that 1) courtship frequency can be expected to respond differently from courtship propensity to changes in OSR and 2) an increase in frequency of agonistic behaviors could occur even if the propensity is not affected by the OSR. In a meta-analysis of studies on courtship competition, we show that frequency measures produced largely opposite results to propensity measures, as predicted by our model. Moreover, courtship propensity increased when the OSR became more biased toward competitors. This presents strong evidence that the OSR affects competition, in the form of courtship, as predicted by OSR theory.
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Affiliation(s)
- Karen de Jong
- Department of Biology, Norwegian University of Science and Technology (NTNU) 7491 Trondheim, Norwayand
| | - Elisabet Forsgren
- The Norwegian Institute for Nature Research (NINA) 7485 Trondheim, Norway
| | - Hanno Sandvik
- Department of Biology, Norwegian University of Science and Technology (NTNU) 7491 Trondheim, Norwayand
| | - Trond Amundsen
- Department of Biology, Norwegian University of Science and Technology (NTNU) 7491 Trondheim, Norwayand
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30
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Procter DS, Moore AJ, Miller CW. The form of sexual selection arising from male-male competition depends on the presence of females in the social environment. J Evol Biol 2012; 25:803-12. [PMID: 22404372 DOI: 10.1111/j.1420-9101.2012.02485.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- D S Procter
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK
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31
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MARIETTE MM, ZAJITSCHEK SRK, GARCIA CM, BROOKS RC. The effects of familiarity and group size on mating preferences in the guppy, Poecilia reticulata. J Evol Biol 2010; 23:1772-82. [DOI: 10.1111/j.1420-9101.2010.02042.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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32
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Klug H, Lindström K, Kokko H. Who to include in measures of sexual selection is no trivial matter. Ecol Lett 2010; 13:1094-102. [DOI: 10.1111/j.1461-0248.2010.01495.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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33
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Zajitschek SRK, Brooks RC. Inbreeding depression in male traits and preference for outbred males in Poecilia reticulata. Behav Ecol 2010. [DOI: 10.1093/beheco/arq077] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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34
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ELGEE KE, EVANS JP, RAMNARINE IW, RUSH SA, PITCHER TE. Geographic variation in sperm traits reflects predation risk and natural rates of multiple paternity in the guppy. J Evol Biol 2010; 23:1331-8. [DOI: 10.1111/j.1420-9101.2010.01996.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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35
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van Dijk RE, Pogány A, Komdeur J, Lloyd P, Székely T. Sexual conflict predicts morphology and behavior in two species of penduline tits. BMC Evol Biol 2010; 10:107. [PMID: 20416066 PMCID: PMC2873415 DOI: 10.1186/1471-2148-10-107] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 04/23/2010] [Indexed: 11/20/2022] Open
Abstract
Background The evolutionary interests of males and females rarely coincide (sexual conflict), and these conflicting interests influence morphology, behavior and speciation in various organisms. We examined consequences of variation in sexual conflict in two closely-related passerine birds with contrasting breeding systems: the Eurasian penduline tit Remiz pendulinus (EPT) exhibiting a highly polygamous breeding system with sexually antagonistic interests over parental care, and the socially monogamous Cape penduline tit Anthoscopus minutus (CPT). We derived four a priori predictions from sexual conflict theory and tested these using data collected in Central Europe (EPT) and South Africa (CPT). Firstly, we predicted that EPTs exhibit more sexually dimorphic plumage than CPTs due to more intense sexual selection. Secondly, we expected brighter EPT males to provide less care than duller males. Thirdly, since song is a sexually selected trait in many birds, male EPTs were expected to exhibit more complex songs than CPT males. Finally, intense sexual conflict in EPT was expected to lead to low nest attendance as an indication of sexually antagonistic interests, whereas we expected more cooperation between parents in CPT consistent with their socially monogamous breeding system. Results Consistent with our predictions EPTs exhibited greater sexual dimorphism in plumage and more complex song than CPTs, and brighter EPT males provided less care than duller ones. EPT parents attended the nest less frequently and less simultaneously than CPT parents. Conclusions These results are consistent with sexual conflict theory: species in which sexual conflict is more manifested (EPT) exhibited a stronger sexual dimorphism and more elaborated sexually selected traits than species with less intense sexual conflict (CPT). Our results are also consistent with the notion that EPTs attempt to force their partner to work harder as expected under sexual conflict: each member of the breeding pair attempts to shift the costs of care to the other parent. More brightly colored males benefit more from desertion than dull ones, because they are more likely to remate with a new female. Taken together, the comparison between two closely related species with contrasting breeding systems suggest that sexual conflict over care has influenced the evolution of behavior and morphology in penduline tits.
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Affiliation(s)
- René E van Dijk
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
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36
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The role of chemical communication in sexual selection: hair-pencil displays in the diamondback moth, Plutella xylostella. Anim Behav 2010. [DOI: 10.1016/j.anbehav.2009.11.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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37
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Bailey MM, Lachapelle KA, Kinnison MT. Ontogenetic selection on hatchery salmon in the wild: natural selection on artificial phenotypes. Evol Appl 2010; 3:340-51. [PMID: 25567929 PMCID: PMC3352472 DOI: 10.1111/j.1752-4571.2009.00115.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Accepted: 12/07/2009] [Indexed: 11/29/2022] Open
Abstract
Captive rearing often alters the phenotypes of organisms that are destined for release into the wild. Natural selection on these unnatural phenotypes could have important consequences for the utility of captive rearing as a restoration approach. We show that normal hatchery practices significantly advance the development of endangered Atlantic salmon (Salmo salar) fry by 30+ days. As a result, hatchery fry might be expected to face strong natural selection resulting from their developmental asynchrony. We investigated patterns of ontogenetic selection acting on hatchery produced salmon fry by experimentally manipulating fry development stage at stocking. Contrary to simple predictions, we found evidence for strong stabilizing selection on the ontogeny of unfed hatchery fry, with weaker evidence for positive directional selection on the ontogeny of fed fry. These selection patterns suggest a seasonally independent tradeoff between abiotic or biotic selection favoring advanced development and physiological selection linked to risk of starvation in unfed fry. We show, through a heuristic exercise, how such selection on ontogeny may exacerbate problems in restoration efforts by impairing fry productivity and reducing effective population sizes by 13-81%.
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Affiliation(s)
- Michael M Bailey
- School of Biology and Ecology, University of Maine Orono, ME, USA
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38
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Abstract
Sexual selection can explain major micro- and macro-evolutionary patterns. Much of current theory predicts that the strength of sexual selection (i) is driven by the relative abundance of males and females prepared to mate (i.e. the operational sex ratio, OSR) and (ii) can be generally estimated by calculating intra-sexual variation in mating success (e.g. the opportunity for sexual selection, I(s)). Here, we demonstrate the problematic nature of these predictions. The OSR and I(s) only accurately predict sexual selection under a limited set of circumstances, and more specifically, only when mate monopolization is extremely strong. If mate monopolization is not strong, using OSR or I(s) as proxies or measures of sexual selection is expected to produce spurious results that lead to the false conclusion that sexual selection is strong when it is actually weak. These findings call into question the validity of empirical conclusions based on these measures of sexual selection.
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Affiliation(s)
- H Klug
- Department of Biological and Environmental Science, University of Helsinki, Finland.
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39
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CROSHAW DEANA. Quantifying sexual selection: a comparison of competing indices with mating system data from a terrestrially breeding salamander. Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2009.01337.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Gasparini C, Marino IAM, Boschetto C, Pilastro A. Effect of male age on sperm traits and sperm competition success in the guppy (Poecilia reticulata). J Evol Biol 2009; 23:124-35. [PMID: 19912453 DOI: 10.1111/j.1420-9101.2009.01889.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Deleterious mutations can accumulate in the germline with age, decreasing the genetic quality of sperm and imposing a cost on female fitness. If these mutations also affect sperm competition ability or sperm production, then females will benefit from polyandry as it incites sperm competition and, consequently, minimizes the mutational load in the offspring. We tested this hypothesis in the guppy (Poecilia reticulata), a species characterized by polyandry and intense sperm competition, by investigating whether age affects post-copulatory male traits and sperm competition success. Females did not discriminate between old and young males in a mate choice experiment. While old males produced longer and slower sperm with larger reserves of strippable sperm, compared to young males, artificial insemination did not reveal any effect of age on sperm competition success. Altogether, these results do not support the hypothesis that polyandry evolved in response to costs associated with mating with old males in the guppy.
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Affiliation(s)
- C Gasparini
- Dipartimento di Biologia, Università di Padova, Padova, Italy.
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41
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de Jong K, Wacker S, Amundsen T, Forsgren E. Do operational sex ratio and density affect mating behaviour? An experiment on the two-spotted goby. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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42
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Lemmon EM. DIVERSIFICATION OF CONSPECIFIC SIGNALS IN SYMPATRY: GEOGRAPHIC OVERLAP DRIVES MULTIDIMENSIONAL REPRODUCTIVE CHARACTER DISPLACEMENT IN FROGS. Evolution 2009; 63:1155-70. [DOI: 10.1111/j.1558-5646.2009.00650.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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43
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Zajitschek S, Brooks R. Distinguishing the Effects of Familiarity, Relatedness, and Color Pattern Rarity on Attractiveness and Measuring Their Effects on Sexual Selection in Guppies (Poecilia reticulata). Am Nat 2008; 172:843-54. [DOI: 10.1086/593001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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44
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Biased sex ratio and low population density increase male mating success in the bug Nysius huttoni (Heteroptera: Lygaeidae). Naturwissenschaften 2008; 96:87-91. [PMID: 18839127 DOI: 10.1007/s00114-008-0455-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 09/15/2008] [Accepted: 09/18/2008] [Indexed: 10/21/2022]
Abstract
Demographic factors such as operational sex ratio (OSR) and local population density (LPD) are temporally and spatially dynamic in the natural environment but the influence of these variables on male mating success and the mechanisms behind it are still poorly understood and highly controversial. Here, we manipulated the OSR and LPD of a seed bug, Nysius huttoni, and carried out a series of mating trials to test how these variables affected male mating success. The two demographic factors had no significant interactions, suggesting that they affect male mating success independently in N. huttoni. In this species male mating success was significantly higher in both male- and female-biased OSR than in even OSR. It is suggested that, in male-biased OSR, the increased intensity of competition and interference does not result in lower male mating success; rather, males may make more effort in courting and females may have more chance to encounter better males, resulting in higher male mating success. In female-biased OSR, females may become less choosy and less likely to reject male mating attempt, leading to the higher male mating success. Lower male mating success in N. huttoni in high LPD may be due to increased interference between males and/or delayed female receptiveness for mating. OSR had a stronger effect on male mating success than LPD in N. huttoni, suggesting that OSR and LPD affect mating success in different ways and intensities.
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