1
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Macedo-Rego RC, Jennions MD, Santos ESA. Does the potential strength of sexual selection differ between mating systems with and without defensive behaviours? A meta-analysis. Biol Rev Camb Philos Soc 2024; 99:1504-1523. [PMID: 38597347 DOI: 10.1111/brv.13078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/11/2024]
Abstract
The Darwin-Bateman paradigm predicts that females enhance their fitness by being choosy and mating with high-quality males, while males should compete to mate with as many females as possible. In many species, males enhance their fitness by defending females and/or resources used by females. That is, males directly defend access to mating opportunities. However, paternity analyses have repeatedly shown that females in most species mate polyandrously, which contradicts traditional expectations that male defensive behaviours lead to monandry. Here, in an extensive meta-analysis, encompassing 109 species and 1026 effect sizes from across the animal kingdom, we tested if the occurrence of defensive behaviours modulates sexual selection on females and males. If so, we can illuminate the extent to which males really succeed in defending access to mating and fertilisation opportunities. We used four different indices of the opportunity for sexual selection that comprise pre-mating and/or post-mating episodes of selection. We found, for both sexes, that the occurrence of defensive behaviours does not modulate the potential strength of sexual selection. This implies that male defensive behaviours do not predict the true intensity of sexual selection. While the most extreme levels of sexual selection on males are in species with male defensive behaviours, which indicates that males do sometimes succeed in restricting females' re-mating ability (e.g. elephant seals, Mirounga leonina), estimates of the opportunity for sexual selection vary greatly across species, regardless of whether or not defensive behaviours occur. Indeed, widespread polyandry shows that females are usually not restricted by male defensive behaviours. In addition, our results indicate that post-mating episodes of selection, such as cryptic female choice and sperm competition, might be important factors modulating the opportunity for sexual selection. We discuss: (i) why male defensive behaviours fail to lower the opportunity for sexual selection among females or fail to elevate it for males; (ii) how post-mating events might influence sexual selection; and (iii) the role of females as active participants in sexual selection. We also highlight that inadequate data reporting in the literature prevented us from extracting effect sizes from many studies that had presumably collected the relevant data.
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Affiliation(s)
- Renato C Macedo-Rego
- Programa de Pós-graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, no. 321, São Paulo, SP 05508-090, Brazil
- Division of Ecology & Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, 10 Marais Street, Stellenbosch, 7600, South Africa
| | - Eduardo S A Santos
- Programa de Pós-graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, no. 321, São Paulo, SP 05508-090, Brazil
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2
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Somjee U, Marting P, Anzaldo S, Simmons LW, Painting CJ. Extreme range in adult body size reveals hidden trade-offs among sexually selected traits. Evolution 2024:qpae084. [PMID: 38900629 DOI: 10.1093/evolut/qpae084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 05/13/2024] [Accepted: 05/24/2024] [Indexed: 06/22/2024]
Abstract
Sexually selected weapons used to monopolize mating opportunities are predicted to trade-off with traits used in competition for fertilization. Yet, the limited size range typically found among adults of a species often precludes clear comparisons between population-level and individual-level relative trait investment. The jousting weevil, Brentus anchorago (Coleoptera: Brentidae), varies more than 26-fold in body mass, which is among the most extreme adult body size ranges of any solitary terrestrial species. We reveal a trade-off at a population level: hypermetric scaling in male weapons (slope = 1.59) and a closely mirrored reversal in allocation to postcopulatory traits (slope = 0.54). Yet, at the individual level, we find the opposite pattern; males that invest relatively more in weapons for their size class also invest more in postcopulatory traits. Across 36 dung beetle and 41 brentine weevil species, we find the allometric slope explains more trait variation at larger body size ranges; in brentines, population-level scaling patterns become more detectable in species with a larger range in adult body size. Our findings reveal that population-level allometries and individual-level trade-offs can both be important in shaping relative trait allocation; we highlight that the adult body size range is rarely examined but may be integral to gaining a deeper understanding of trade-offs in reproductive allocation.
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Affiliation(s)
- Ummat Somjee
- Department of Integrative Biology, University of Texas, Austin, TX, United States
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Peter Marting
- Department of Biological Sciences, Auburn University, Auburn, AL, United States
| | - Salvatore Anzaldo
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Leigh W Simmons
- School of Biological Sciences, University of Western Australia, Perth, WA, Australia
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3
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Reuland C, Simmons LW, Lüpold S, Fitzpatrick JL. Weapons Evolve Faster Than Sperm in Bovids and Cervids. Cells 2021; 10:cells10051062. [PMID: 33947050 PMCID: PMC8145498 DOI: 10.3390/cells10051062] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/25/2021] [Accepted: 04/27/2021] [Indexed: 12/13/2022] Open
Abstract
In polyandrous species, males face reproductive competition both before and after mating. Sexual selection thus shapes the evolution of both pre- and postcopulatory traits, creating competing demands on resource allocation to different reproductive episodes. Traits subject to strong selection exhibit accelerated rates of phenotypic divergence, and examining evolutionary rates may inform us about the relative importance and potential fitness consequences of investing in traits under either pre- or postcopulatory sexual selection. Here, we used a comparative approach to assess evolutionary rates of key competitive traits in two artiodactyl families, bovids (family Bovidae) and cervids (family Cervidae), where male–male competition can occur before and after mating. We quantified and compared evolutionary rates of male weaponry (horns and antlers), body size/mass, testes mass, and sperm morphometrics. We found that weapons evolve faster than sperm dimensions. In contrast, testes and body mass evolve at similar rates. These results suggest strong, but differential, selection on both pre- and postcopulatory traits in bovids and cervids. Furthermore, we documented distinct evolutionary rates among different sperm components, with sperm head and midpiece evolving faster than the flagellum. Finally, we demonstrate that, despite considerable differences in weapon development between bovids and cervids, the overall evolutionary patterns between these families were broadly consistent.
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Affiliation(s)
- Charel Reuland
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden;
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Crawley, WA 6009, Australia;
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland;
| | - John L. Fitzpatrick
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden;
- Correspondence:
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4
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Measuring Pre- and Post-Copulatory Sexual Selection and Their Interaction in Socially Monogamous Species with Extra-Pair Paternity. Cells 2021; 10:cells10030620. [PMID: 33799610 PMCID: PMC7999480 DOI: 10.3390/cells10030620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 01/08/2023] Open
Abstract
When females copulate with multiple males, pre- and post-copulatory sexual selection may interact synergistically or in opposition. Studying this interaction in wild populations is complex and potentially biased, because copulation and fertilization success are often inferred from offspring parentage rather than being directly measured. Here, I simulated 15 species of socially monogamous birds with varying levels of extra-pair paternity, where I could independently cause a male secondary sexual trait to improve copulation success, and a sperm trait to improve fertilization success. By varying the degree of correlation between the male and sperm traits, I show that several common statistical approaches, including univariate selection gradients and paired t-tests comparing extra-pair males to the within-pair males they cuckolded, can give highly biased results for sperm traits. These tests should therefore be avoided for sperm traits in socially monogamous species with extra-pair paternity, unless the sperm trait is known to be uncorrelated with male trait(s) impacting copulation success. In contrast, multivariate selection analysis and a regression of the proportion of extra-pair brood(s) sired on the sperm trait of the extra-pair male (including only broods where the male sired ≥1 extra-pair offspring) were unbiased, and appear likely to be unbiased under a broad range of conditions for this mating system. In addition, I investigated whether the occurrence of pre-copulatory selection impacted the strength of post-copulatory selection, and vice versa. I found no evidence of an interaction under the conditions simulated, where the male trait impacted only copulation success and the sperm trait impacted only fertilization success. Instead, direct selection on each trait was independent of whether the other trait was under selection. Although pre- and post-copulatory selection strength was independent, selection on the two traits was positively correlated across species because selection on both traits increased with the frequency of extra-pair copulations in these socially monogamous species.
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5
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Supriya K, Price TD, Rowe M. Resource variation generates positive correlations between pre- and postcopulatory sexual traits. Behav Ecol 2018. [DOI: 10.1093/beheco/ary170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- K Supriya
- Committee on Evolutionary Biology, University of Chicago, Chicago, USA
| | - Trevor D Price
- Department of Ecology and Evolution, University of Chicago, Chicago, USA
| | - Melissah Rowe
- Natural History Museum, University of Oslo, Blindern, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Blindern, Oslo, Norway
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6
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Wu H, Jiang T, Huang X, Feng J. Patterns of sexual size dimorphism in horseshoe bats: Testing Rensch's rule and potential causes. Sci Rep 2018; 8:2616. [PMID: 29422495 PMCID: PMC5805768 DOI: 10.1038/s41598-018-21077-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 01/29/2018] [Indexed: 11/10/2022] Open
Abstract
Rensch's rule, stating that sexual size dimorphism (SSD) becomes more evident and male-biased with increasing body size, has been well supported for taxa that exhibit male-biased SSD. Bats, primarily having female-biased SSD, have so far been tested for whether SSD allometry conforms to Rensch's rule in only three studies. However, these studies did not consider phylogeny, and thus the mechanisms underlying SSD variations in bats remain unclear. Thus, the present study reviewed published and original data, including body size, baculum size, and habitat types in 45 bats of the family Rhinolophidae to determine whether horseshoe bats follow Rensch's rule using a phylogenetic comparative framework. We also investigated the potential effect of postcopulatory sexual selection and habitat type on SSD. Our findings indicated that Rensch's rule did not apply to Rhinolophidae, suggesting that SSD did not significantly vary with increasing size. This pattern may be attributable interactions between weak sexual selection to male body size and strong fecundity selection for on female body size. The degree of SSD among horseshoe bats may be attributed to a phylogenetic effect rather than to the intersexual competition for food or to baculum length. Interestingly, we observed that species in open habitats exhibited greater SSD than those in dense forests, suggesting that habitat types may be associated with variations in SSD in horseshoe bats.
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Affiliation(s)
- Hui Wu
- College of Animal Science and Technology, Jilin Agricultural University, Xincheng ST 2888, Changchun, 130118, China
- Jilin Provincal Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Jingyue St 2555, Changchun, 130117, China
| | - Tinglei Jiang
- Jilin Provincal Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Jingyue St 2555, Changchun, 130117, China.
- Key Laboratory of Vegetation Ecology of Education Ministry, Institute of Grassland Science, Northeast Normal University, Changchun, 130024, China.
| | - Xiaobin Huang
- Jilin Provincal Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Jingyue St 2555, Changchun, 130117, China
| | - Jiang Feng
- College of Animal Science and Technology, Jilin Agricultural University, Xincheng ST 2888, Changchun, 130118, China.
- Jilin Provincal Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Jingyue St 2555, Changchun, 130117, China.
- Key Laboratory of Vegetation Ecology of Education Ministry, Institute of Grassland Science, Northeast Normal University, Changchun, 130024, China.
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7
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Carranza J, Roldán M, Duarte JMB. Lack of mate selectivity for genetic compatibility within the red brocket deer Mazama americana complex. Mamm Biol 2018. [DOI: 10.1016/j.mambio.2017.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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9
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(Ginny) Greenway E, Balfour VL, Shuker DM. Can females choose to avoid mating failure in the seed bug Lygaeus simulans? Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Lemaître JF, Gaillard JM. Reproductive senescence: new perspectives in the wild. Biol Rev Camb Philos Soc 2017; 92:2182-2199. [PMID: 28374548 DOI: 10.1111/brv.12328] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/23/2017] [Accepted: 03/03/2017] [Indexed: 11/26/2022]
Abstract
According to recent empirical studies, reproductive senescence, the decline in reproductive success with increasing age, seems to be nearly ubiquitous in the wild. However, a clear understanding of the evolutionary causes and consequences of reproductive senescence is still lacking and requires new and integrative approaches. After identifying the sequential and complex nature of female reproductive senescence, we show that the relative contributions of physiological decline and alterations in the efficiency of parental care to reproductive senescence remain unknown and need to be assessed in the light of current evolutionary theories of ageing. We demonstrate that, although reproductive senescence is generally studied only from the female viewpoint, age-specific female reproductive success strongly depends on male-female interactions. Thus, a reduction in male fertilization efficiency with increasing age has detrimental consequences for female fitness. Lastly, we call for investigations of the role of environmental conditions on reproductive senescence, which could provide salient insights into the underlying sex-specific mechanisms of reproductive success. We suggest that embracing such directions should allow building new bridges between reproductive senescence and the study of sperm competition, parental care, mate choice and environmental conditions.
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Affiliation(s)
- Jean-François Lemaître
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
| | - Jean-Michel Gaillard
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
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11
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Chechi TS, Ali Syed Z, Prasad NG. Virility does not imply immensity: Testis size, accessory gland size and ejaculate depletion pattern do not evolve in response to experimental manipulation of sex ratio in Drosophila melanogaster. JOURNAL OF INSECT PHYSIOLOGY 2017; 98:67-73. [PMID: 27913151 DOI: 10.1016/j.jinsphys.2016.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/21/2016] [Accepted: 11/22/2016] [Indexed: 06/06/2023]
Abstract
Sperm competition theory predicts that with increase in sperm competition, males either invest more in reproductive organ(s) and/or improve ejaculate investment. We test this idea using experimental evolution in Drosophila melanogaster. We maintained replicate populations of Drosophila melanogaster under male (M) and female (F) biased sex ratio regimes for more than a hundred generations with the result that males from the M regime evolved higher sperm competitive abilities relative to males from the F regime. In the present study, we measured the testes and the accessory gland size of virgin and singly mated males from the M and F regimes. The M and F males do not differ in either testis or accessory gland size. Additionally, ejaculate investment is not different in the M and F males, as measured by reduction in testis and accessory gland sizes. Thus, contrary to theoretical prediction and evidence from other species, we found that evolved differences in sperm competitive ability are not necessarily due to evolution of testis/accessory gland size or strategic ejaculate investment in these populations.
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Affiliation(s)
- Tejinder Singh Chechi
- Indian Institute of Science Education and Research, Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali, Punjab 140306, India
| | - Zeeshan Ali Syed
- Indian Institute of Science Education and Research, Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali, Punjab 140306, India
| | - Nagaraj Guru Prasad
- Indian Institute of Science Education and Research, Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali, Punjab 140306, India.
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12
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Lack of Evolution of Sexual Size Dimorphism in Heteromyidae (Rodentia): The Influence of Resource Defense and the Trade-Off between Pre- and Post-Copulatory Trait Investment. Evol Biol 2016. [DOI: 10.1007/s11692-016-9390-7] [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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13
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Evans JP, Garcia-Gonzalez F. The total opportunity for sexual selection and the integration of pre- and post-mating episodes of sexual selection in a complex world. J Evol Biol 2016; 29:2338-2361. [PMID: 27520979 DOI: 10.1111/jeb.12960] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 08/05/2016] [Accepted: 08/05/2016] [Indexed: 12/30/2022]
Abstract
It is well known that sexual selection can target reproductive traits during successive pre- and post-mating episodes of selection. A key focus of recent studies has been to understand and quantify how these episodes of sexual selection interact to determine overall variance in reproductive success. In this article, we review empirical developments in this field but also highlight the considerable variability in patterns of pre- and post-mating sexual selection, attributable to variation in patterns of resource acquisition and allocation, ecological and social factors, genotype-by-environment interaction and possible methodological factors that might obscure such patterns. Our aim is to highlight how (co)variances in pre- and post-mating sexually selected traits can be sensitive to changes in a range of ecological and environmental variables. We argue that failure to capture this variation when quantifying the opportunity for sexual selection may lead to erroneous conclusions about the strength, direction or form of sexual selection operating on pre- and post-mating traits. Overall, we advocate for approaches that combine measures of pre- and post-mating selection across contrasting environmental or ecological gradients to better understand the dynamics of sexual selection in polyandrous species. We also discuss some directions for future research in this area.
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Affiliation(s)
- J P Evans
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia
| | - F Garcia-Gonzalez
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia.,Doñana Biological Station, Spanish Research Council CSIC, Sevilla, Spain
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14
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Kahrl AF, Cox CL, Cox RM. Correlated evolution between targets of pre- and postcopulatory sexual selection across squamate reptiles. Ecol Evol 2016; 6:6452-6459. [PMID: 27777721 PMCID: PMC5058519 DOI: 10.1002/ece3.2344] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 06/28/2016] [Accepted: 06/30/2016] [Indexed: 11/25/2022] Open
Abstract
Sexual selection reflects the joint contributions of precopulatory selection, which arises from variance in mating success, and postcopulatory selection, which arises from variance in fertilization success. The relative importance of each episode of selection is variable among species, and comparative evidence suggests that traits targeted by precopulatory selection often covary in expression with those targeted by postcopulatory selection when assessed across species, although the strength and direction of this association varies considerably among taxa. We tested for correlated evolution between targets of pre‐ and postcopulatory selection using data on sexual size dimorphism (SSD) and testis size from 151 species of squamate reptiles (120 lizards, 31 snakes). In squamates, male–male competition for mating opportunities often favors large body size, such that the degree of male‐biased SSD is associated with the intensity of precopulatory selection. Likewise, competition for fertilization often favors increased sperm production, such that testis size (relative to body size) is associated with the intensity of postcopulatory selection. Using both conventional and phylogenetically based analyses, we show that testis size consistently decreases as the degree of male‐biased SSD increases across lizards and snakes. This evolutionary pattern suggests that strong precopulatory selection may often constrain the opportunity for postcopulatory selection and that the relative importance of each selective episode may determine the optimal resolution of energy allocation trade‐offs between traits subject to each form of sexual selection.
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Affiliation(s)
- Ariel F Kahrl
- Department of Biology University of Virginia Charlottesville Virginia 22904
| | - Christian L Cox
- Department of Biology Georgia Southern University Statesboro Georgia 30460
| | - Robert M Cox
- Department of Biology University of Virginia Charlottesville Virginia 22904
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15
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Affiliation(s)
- G. A. Parker
- Institute of Integrative Biology; University of Liverpool; Liverpool UK
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16
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Lüpold S, Simmons LW, Tomkins JL, Fitzpatrick JL. No evidence for a trade-off between sperm length and male premating weaponry. J Evol Biol 2015; 28:2187-95. [PMID: 26332435 DOI: 10.1111/jeb.12742] [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: 07/13/2015] [Revised: 08/24/2015] [Accepted: 08/25/2015] [Indexed: 01/15/2023]
Abstract
Male ornaments and armaments that mediate success in mate acquisition and ejaculate traits influencing competitive fertilization success are under intense sexual selection. However, relative investment in these pre- and post-copulatory traits depends on the relative importance of either selection episode and on the energetic costs and fitness gains of investing in these traits. Theoretical and empirical work has improved our understanding of how precopulatory sexual traits and investments in sperm production covary in this context. It has recently also been suggested that male weapon size may trade off with sperm length as another post-copulatory sexual trait, but the theoretical framework for this suggestion remains unclear. We evaluated the relationship between precopulatory armaments and sperm length, previously reported in ungulates, in five taxa as well as meta-analytically. Within and between taxa, we found no evidence for a negative or positive relationship between sperm length and male traits that are important in male-male contest competition. It is important to consider pre- and post-copulatory sexual selection together to understand fitness, and to study investments in different reproductive traits jointly rather than separately. A trade-off between pre- and post-copulatory sexual traits may not manifest itself in sperm length but rather in sperm number or function. Particularly in large-bodied taxa such as ungulates, sperm number is more variable interspecifically and likely to be under more intense selection than sperm length. We discuss our and the previous results in this context.
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Affiliation(s)
- S Lüpold
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK.,Department of Biology, Life Sciences Complex, Syracuse University, Syracuse, NY, USA
| | - L W Simmons
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia
| | - J L Tomkins
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia
| | - J L Fitzpatrick
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK
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17
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Dines JP, Mesnick SL, Ralls K, May-Collado L, Agnarsson I, Dean MD. A trade-off between precopulatory and postcopulatory trait investment in male cetaceans. Evolution 2015; 69:1560-1572. [PMID: 25929734 DOI: 10.1111/evo.12676] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 04/21/2015] [Indexed: 11/30/2022]
Abstract
Mating with multiple partners is common across species, and understanding how individual males secure fertilization in the face of competition remains a fundamental goal of evolutionary biology. Game theory stipulates that males have a fixed budget for reproduction that can lead to a trade-off between investment in precopulatory traits such as body size, armaments, and ornaments, and postcopulatory traits such as testis size and spermatogenic efficiency. Recent theoretical and empirical studies have shown that if males can monopolize access to multiple females, they will invest disproportionately in precopulatory traits and less in postcopulatory traits. Using phylogenetically controlled comparative methods, we demonstrate that across 58 cetacean species with the most prominent sexual dimorphism in size, shape, teeth, tusks, and singing invest significantly less in relative testes mass. In support of theoretical predictions, these species tend to show evidence of male contests, suggesting there is opportunity for winners to monopolize access to multiple females. Our approach provides a robust dataset with which to make predictions about male mating strategies for the many cetacean species for which adequate behavioral observations do not exist.
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Affiliation(s)
- James P Dines
- Mammalogy, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California, 90007.,Integrative and Evolutionary Biology, University of Southern California, Los Angeles, California, 90089
| | - Sarah L Mesnick
- Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 8901 La Jolla Shores Drive, La Jolla, California, 92037
| | - Katherine Ralls
- Smithsonian Conservation Biology Institute, National Zoological Park, 3001 Connecticut Ave NW, Washington, DC, 20008
| | - Laura May-Collado
- Department of Biology, University of Vermont, 109 Carrigan Drive, Burlington, Vermont, 05405
| | - Ingi Agnarsson
- Department of Biology, University of Vermont, 109 Carrigan Drive, Burlington, Vermont, 05405
| | - Matthew D Dean
- Molecular and Computational Biology, University of Southern California, Los Angeles, California, 90089
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