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Kustra MC, Stiver KA, Marsh-Rollo S, Hellmann JK, Alonzo SH. Social Environment Influences the Temporal Dynamics of Sneak-Spawning in a Fish with Alternative Reproductive Tactics. Am Nat 2023; 202:181-191. [PMID: 37531281 DOI: 10.1086/725057] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
AbstractSeveral predictions of sperm competition theory are not well supported empirically. One potential reason is that most current theory and empirical research ignore how the social environment influence the temporal dynamics of mating. We propose that understanding these dynamics is key to understanding sexual selection and improving the predictive power of theory. To demonstrate the importance of these dynamics, we quantify how males' social role, interactions among males, and current social environment influence the timing of mating in Symphodus ocellatus, a species with three alternative male reproductive tactics. Nesting males spawn synchronously with females; sneakers and satellites sneak-spawn with some time delay. Satellites also cooperate with nesting males. We found that satellites have shorter sneak-spawning delays than sneakers, a benefit of their cooperation with nesting males. Sneak-spawning delays decreased with increasing nest activity for sneakers but not for satellites, suggesting that sneakers may benefit from increased sperm competition intensity. Current sperm competition models ignore this potential benefit, which may be why the prediction that males should decrease investment when sperm competition involves more than two males is not well supported. Our study provides insight into mechanisms that drive variation in the timing of spawning, which could explain mismatches between theoretical and empirical results.
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2
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Morimoto J, McDonald GC, Wigby S. Social group composition modulates the role of last male sperm precedence in post-copulatory sexual selection. J Evol Biol 2023; 36:1102-1115. [PMID: 37341163 PMCID: PMC10946607 DOI: 10.1111/jeb.14191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 05/05/2023] [Accepted: 05/24/2023] [Indexed: 06/22/2023]
Abstract
In many species, the order in which males mate with a female explains much of the variation in paternity arising from post-copulatory sexual selection. Research in Drosophila suggests that mating order may account for the majority of the variance in male reproductive success. However, the effects of mating order on paternity bias might not be static but could potentially vary with social or environmental factors. To test this idea, we used an existing dataset, collated from an experiment we previously published (Morimoto et al., PLoS One, 11, 2016, e0154468), with the addition of unpublished data from the same experiment. These previous experiments manipulated larval density in Drosophila melanogaster which generated variation in male and female body size, assembled groups of individuals of different sizes, and measured the mating success and paternity share of focal males. The data presented here provides information on each focal male's mating order and the frequency in which focal males remated with same females ('repetitive matings'). We combined this information with our previously reported focal male reproductive success to partition variance in paternity into male mating order and repetitive matings across groups that differed in the body size composition of males and females. We found, as expected, that male mating order explained a considerable portion of the variance in male paternity. However, we also found that the impact of male mating order on male paternity was influenced by the body size composition of groups. Specifically, males that tended to mate last had a greater paternity advantage, and displayed lower variance, in groups containing a heterogenous mixture male body sizes than in groups with a single male body size. Repetitive mating only had a minor contribution to the variance in male paternity share across all experiments. Overall, our findings contribute to the growing body of research showing that post-copulatory sexual selection is subject to socio-ecological influences.
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Affiliation(s)
- Juliano Morimoto
- School of Biological SciencesUniversity of AberdeenAberdeenUK
- Programa de Pós‐graduação em Ecologia e ConservaçãoUniversidade Federal do ParanáCuritibaBrazil
- Institute of MathematicsUniversity of Aberdeen, King's CollegeAberdeenUK
| | - Grant C. McDonald
- Department of EcologyUniversity of Veterinary Medicine BudapestBudapestHungary
| | - Stuart Wigby
- Department of Evolution, Ecology, and Behaviour, Institute of Infection, Veterinary & Ecological SciencesUniversity of LiverpoolLiverpoolUK
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3
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Sorci G, Hussein HA, Levêque G, Saint Jalme M, Lacroix F, Hingrat Y, Lesobre L. Ranking parameters driving siring success during sperm competition in the North African houbara bustard. Commun Biol 2023; 6:305. [PMID: 36949210 PMCID: PMC10033649 DOI: 10.1038/s42003-023-04698-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 03/10/2023] [Indexed: 03/24/2023] Open
Abstract
Sperm competition is a powerful force driving the evolution of ejaculate and sperm traits. However, the outcome of sperm competition depends on many traits that extend beyond ejaculate quality. Here, we study male North African houbara bustards (Chlamydotis undulata undulata) competing for egg fertilization, after artificial insemination, with the aim to rank the importance of 14 parameters as drivers of siring success. Using a machine learning approach, we show that traits independent of male quality (i.e., insemination order, delay between insemination and egg laying) are the most important predictors of siring success. Traits describing intrinsic male quality (i.e., number of sperm in the ejaculate, mass motility index) are also positively associated with siring success, but their contribution to explaining the outcome of sperm competition is much lower than for insemination order. Overall, this analysis shows that males mating at the last position in the mating sequence have the best chance to win the competition for egg fertilization. This raises the question of the importance of female behavior as determinant of mating order.
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Affiliation(s)
- Gabriele Sorci
- Biogéosciences, UMR 6282 CNRS, Université de Bourgogne, Dijon, France.
| | - Hiba Abi Hussein
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | | | - Michel Saint Jalme
- Centre d'Ecologie et des Sciences de la Conservation, CESCO, Museum National d'Histoire Naturelle, CNRS, Ménagerie le zoo du Jardin des Plantes, Sorbonne Université, Paris, France
| | - Frédéric Lacroix
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | - Yves Hingrat
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | - Loïc Lesobre
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
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Carleial R, Pizzari T, Richardson DS, McDonald GC. Disentangling the causes of temporal variation in the opportunity for sexual selection. Nat Commun 2023; 14:1006. [PMID: 36813810 PMCID: PMC9947164 DOI: 10.1038/s41467-023-36536-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 02/06/2023] [Indexed: 02/24/2023] Open
Abstract
In principle, temporal fluctuations in the potential for sexual selection can be estimated as changes in intrasexual variance in reproductive success (i.e. the opportunity for selection). However, we know little about how opportunity measures vary over time, and the extent to which such dynamics are affected by stochasticity. We use published mating data from multiple species to investigate temporal variation in the opportunity for sexual selection. First, we show that the opportunity for precopulatory sexual selection typically declines over successive days in both sexes and shorter sampling periods lead to substantial overestimates. Second, by utilising randomised null models, we also find that these dynamics are largely explained by an accumulation of random matings, but that intrasexual competition may slow temporal declines. Third, using data from a red junglefowl (Gallus gallus) population, we show that declines in precopulatory measures over a breeding period were mirrored by declines in the opportunity for both postcopulatory and total sexual selection. Collectively, we show that variance-based metrics of selection change rapidly, are highly sensitive to sampling durations, and likely lead to substantial misinterpretation if used as indicators of sexual selection. However, simulations can begin to disentangle stochastic variation from biological mechanisms.
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Affiliation(s)
- Rômulo Carleial
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3SZ, UK. .,Science Directorate, Royal Botanic Gardens, Kew, Richmond, TW9 3AE, UK.
| | - Tommaso Pizzari
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3SZ, UK
| | | | - Grant C McDonald
- Department of Ecology, University of Veterinary Medicine Budapest, Budapest, 1077, Hungary.
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5
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Sperm Numbers as a Paternity Guard in a Wild Bird. Cells 2022; 11:cells11020231. [PMID: 35053349 PMCID: PMC8773506 DOI: 10.3390/cells11020231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/08/2022] [Accepted: 01/09/2022] [Indexed: 12/02/2022] Open
Abstract
Sperm competition is thought to impose strong selection on males to produce competitive ejaculates to outcompete rival males under competitive mating conditions. Our understanding of how different sperm traits influence fertilization success, however, remains limited, especially in wild populations. Recent literature highlights the importance of incorporating multiple ejaculate traits and pre-copulatory sexually selected traits in analyses aimed at understanding how selection acts on sperm traits. However, variation in a male’s ability to gain fertilization success may also depend upon a range of social and ecological factors that determine the opportunity for mating events both within and outside of the social pair-bond. Here, we test for an effect of sperm quantity and sperm size on male reproductive success in the red-back fairy-wren (Malurus melanocephalus) while simultaneously accounting for pre-copulatory sexual selection and potential socio-ecological correlates of male mating success. We found that sperm number (i.e., cloacal protuberance volume), but not sperm morphology, was associated with reproductive success in male red-backed fairy-wrens. Most notably, males with large numbers of sperm available for copulation achieved greater within-pair paternity success. Our results suggest that males use large sperm numbers as a defensive strategy to guard within-pair paternity success in a system where there is a high risk of sperm competition and female control of copulation. Finally, our work highlights the importance of accounting for socio-ecological factors that may influence male mating opportunities when examining the role of sperm traits in determining male reproductive success.
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Selection on Sperm Count, but Not on Sperm Morphology or Velocity, in a Wild Population of Anolis Lizards. Cells 2021; 10:cells10092369. [PMID: 34572018 PMCID: PMC8464841 DOI: 10.3390/cells10092369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/04/2021] [Accepted: 09/06/2021] [Indexed: 12/25/2022] Open
Abstract
Sperm competition is a widespread phenomenon that shapes male reproductive success. Ejaculates present many potential targets for postcopulatory selection (e.g., sperm morphology, count, and velocity), which are often highly correlated and potentially subject to complex multivariate selection. Although multivariate selection on ejaculate traits has been observed in laboratory experiments, it is unclear whether selection is similarly complex in wild populations, where individuals mate frequently over longer periods of time. We measured univariate and multivariate selection on sperm morphology, sperm count, and sperm velocity in a wild population of brown anole lizards (Anolis sagrei). We conducted a mark-recapture study with genetic parentage assignment to estimate individual reproductive success. We found significant negative directional selection and negative quadratic selection on sperm count, but we did not detect directional or quadratic selection on any other sperm traits, nor did we detect correlational selection on any trait combinations. Our results may reflect pressure on males to produce many small ejaculates and mate frequently over a six-month reproductive season. This study is the first to measure multivariate selection on sperm traits in a wild population and provides an interesting contrast to experimental studies of external fertilizers, which have found complex multivariate selection on sperm phenotypes.
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Meta-analytic evidence that animals rarely avoid inbreeding. Nat Ecol Evol 2021; 5:949-964. [PMID: 33941905 DOI: 10.1038/s41559-021-01453-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 03/24/2021] [Indexed: 02/02/2023]
Abstract
Animals are usually expected to avoid mating with relatives (kin avoidance) as incestuous mating can lead to the expression of inbreeding depression. Yet, theoretical models predict that unbiased mating with regards to kinship should be common, and that under some conditions, the inclusive fitness benefits associated with inbreeding can even lead to a preference for mating with kin. This mismatch between empirical and theoretical expectations generates uncertainty as to the prevalence of inbreeding avoidance in animals. Here, we synthesized 677 effect sizes from 139 experimental studies of mate choice for kin versus non-kin in diploid animals, representing 40 years of research, using a meta-analytical approach. Our meta-analysis revealed little support for the widely held view that animals avoid mating with kin, despite clear evidence of publication bias. Instead, unbiased mating with regards to kinship appears widespread across animals and experimental conditions. The significance of a variety of moderators was explored using meta-regressions, revealing that the degree of relatedness and prior experience with kin explained some variation in the effect sizes. Yet, we found no difference in kin avoidance between males and females, choice and no-choice experiments, mated and virgin animals or between humans and animals. Our findings highlight the need to rethink the widely held view that inbreeding avoidance is a given in experimental studies.
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Roth AM, Dingemanse NJ, Nakagawa S, McDonald GC, Løvlie H, Robledo-Ruiz DA, Pizzari T. Sexual selection and personality: Individual and group-level effects on mating behaviour in red junglefowl. J Anim Ecol 2021; 90:1288-1306. [PMID: 33630314 DOI: 10.1111/1365-2656.13454] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/01/2021] [Indexed: 11/28/2022]
Abstract
Despite increasing evidence of the importance of repeatable among-individual differences in behaviour (animal personality) in ecology and evolution, little remains known about the role of animal personalities in sexual selection. Here, we present an investigation of the hypothesis that the personalities of individuals and their sexual partners play a role in different episodes of sexual selection, and the extent to which these effects are modulated by the social environment. We first examined how two repeatable behaviours-exploration and boldness-are associated with pre- and postcopulatory sexual selection in male red junglefowl Gallus gallus, using replicate groups across three experimental sex ratio treatments. We further explored how the social environment modulates relationships between male personality and mating performance, and whether mating is assortative or disassortative with respect to exploration or boldness. Finally, we examined behavioural mechanisms linking personality with mating performance. Across all sex ratios, the fastest and slowest exploring males courted females proportionally less, and faster exploring males associated with females more and received more sexual solicitations. In female-biased groups, the fastest and slowest exploring males experienced the highest mating success and lowest sperm competition intensity. Faster exploring males also obtained more mates in female-biased groups when their competitors were, on average, slower exploring, and the proportion of matings obtained by fast-exploring males decreased with the proportion of fast-exploring males in a group, consistent with negative frequency-dependent sexual selection. While boldness did not predict mating performance, there was a tendency for individuals to mate disassortatively with respect to boldness. Collectively, our results suggest that male exploration can play a role in sexual selection, and that sexual selection on personality is complex and contingent on the social environment.
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Affiliation(s)
- Allison M Roth
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK.,Department of Biology, University of Florida, Gainesville, FL, USA
| | - Niels J Dingemanse
- Behavioural Ecology, Department of Biology, Ludwig Maximilians University of Munich, Munich, Germany
| | - Shinichi Nakagawa
- Evolution and Ecology Research Centre and School of Biological and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Grant C McDonald
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK.,Department of Ecology, University of Veterinary Medicine Budapest, Budapest, Hungary
| | - Hanne Løvlie
- Department of Physics Chemistry and Biology, IFM Biology, Linköping University, Linköping, Sweden
| | | | - Tommaso Pizzari
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK
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9
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Simmons LW, Wedell N. Fifty years of sperm competition: the structure of a scientific revolution. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200060. [PMID: 33070719 DOI: 10.1098/rstb.2020.0060] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Leigh W Simmons
- Centre for Evolutionary Biology, The University of Western Australia, Crawley 6009, Australia
| | - Nina Wedell
- Centre for Ecology and Conservation, University of Exeter, Cornwall, Penryn TR10 9FE, UK
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