1
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Chung MHJ, Mahmud-Al-Hasan M, Jennions MD, Head ML. Effects of inbreeding and elevated rearing temperatures on strategic sperm investment. Behav Ecol 2024; 35:arae044. [PMID: 38903732 PMCID: PMC11187721 DOI: 10.1093/beheco/arae044] [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: 11/15/2023] [Revised: 03/24/2024] [Accepted: 06/04/2024] [Indexed: 06/22/2024] Open
Abstract
Males often strategically adjust the number of available sperm based on the social context (i.e. sperm priming response), but it remains unclear how environmental and genetic factors shape this adjustment. In freshwater ecosystems, high ambient temperatures often lead to isolated pools of hotter water in which inbreeding occurs. Higher water temperatures and inbreeding can impair fish development, potentially disrupting sperm production. We used guppies (Poecilia reticulata) to investigate how developmental temperature (26 °C, 30 °C) and male inbreeding status (inbred, outbred) influence their sperm priming response. We also tested if sperm priming was affected by whether the female was a relative (sister) and whether she was inbred or outbred. There was no effect of rearing temperature; male inbreeding status alone determined the number of available sperm in response to female presence, her inbreeding status, and her relatedness. Inbred males produced significantly more sperm in the presence of an unrelated, outbred female than when no female was present. Conversely, outbred males did not alter the number of sperm available in response to female presence or relatedness. Moreover, inbred males produced marginally more sperm when exposed to an unrelated female that was outbred rather than inbred, but there was no difference when exposed to an inbred female that was unrelated versus related. Together, a sperm priming response was only observed in inbred males when exposed to an outbred female. Outbred females in our study were larger than inbred females, suggesting that inbred males strategically allocated ejaculate resources toward females in better condition.
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Affiliation(s)
- Meng-Han Joseph Chung
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Md Mahmud-Al-Hasan
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Megan L Head
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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2
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Evans JP, Turnbull EJ, Lymbery RA. Testing for age-dependent effects of dietary restriction on the strength of condition dependence in ejaculate traits in the guppy ( Poecilia reticulata). ROYAL SOCIETY OPEN SCIENCE 2023; 10:230805. [PMID: 37650067 PMCID: PMC10465203 DOI: 10.1098/rsos.230805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/07/2023] [Indexed: 09/01/2023]
Abstract
Ejaculates can be costly to produce and depend on an individual's condition, defined as the pool of resources allocated to fitness. A method for assessing condition dependence is to manipulate resource availability and test for a reduction in trait expression. Here, we assess the effects of dietary restriction on two determinants of reproductive fitness in the guppy Poecilia reticulata-sperm production and sperm motility. Importantly, we administered dietary restriction at distinct developmental stages to test: (1) whether dietary restriction, when applied exclusively to juveniles, compromised the ejaculates of newly mature males; (2) whether any observed effects of dietary restriction seen in (1) were reversible when fish returned to an unrestricted diet; and (3) whether dietary restriction applied exclusively to adults influenced ejaculates. We found detrimental effects of resource limitation on both traits, and these were consistent across the three developmental stages tested. Furthermore, dietary restriction reduced male body weight, but this was partially reversed when diet-stressed juveniles (i.e. group 2) returned to unrestricted diets. This latter result suggests that diet-stressed males may sacrifice growth in order to maintain their investment in ejaculates. Together these findings underscore the importance of resource acquisition in determining the expression of ejaculate traits.
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Affiliation(s)
- Jonathan P. Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth 6009, WA, Australia
| | - Elizabeth J. Turnbull
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth 6009, WA, Australia
| | - Rowan A. Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth 6009, WA, Australia
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3
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Lymbery RA, Alvaro BJ, Evans JP. Does diet influence ejaculate expenditure under experimentally altered risk of sperm competition in guppies? Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Galluccio E, Lymbery RA, Wilson A, Evans JP. Personality, sperm traits and a test for their combined dependence on male condition in guppies. ROYAL SOCIETY OPEN SCIENCE 2022. [PMID: 35706668 DOI: 10.5061/dryad.00000005n] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
There is evidence that animal personality can affect sexual selection, with studies reporting that male behavioural types are associated with success during pre- and post-copulatory sexual selection. Given these links between personality and sexual traits, and the accumulating evidence that their expression can depend on an individual's dietary status (i.e. condition), a novel prediction is that changes in a male's diet should alter both the average expression of personality and sexual traits, and their covariance. We tested these predictions using the guppy Poecilia reticulata, a species previously shown to exhibit strong condition dependence in ejaculate traits and a positive correlation between sperm production and individual variation in boldness. Contrary to expectation, we found that dietary restriction-when administered in mature adult males-did not affect the expression of either behavioural (boldness and activity) or ejaculate traits, although we did find that males subjected to dietary stress exhibited a positive association between sperm velocity and boldness that was not apparent in the unrestricted diet group. This latter finding points to possible context-dependent patterns of covariance between sexually selected traits and personalities, which may have implications for patterns of selection and evolutionary processes under fluctuating environmental conditions.
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Affiliation(s)
- Edward Galluccio
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
| | - Rowan A Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
| | - Alastair Wilson
- Centre for Ecology and Evolution, University of Exeter, Cornwall Campus, Penryn, UK
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
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5
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Galluccio E, Lymbery RA, Wilson A, Evans JP. Personality, sperm traits and a test for their combined dependence on male condition in guppies. ROYAL SOCIETY OPEN SCIENCE 2022. [PMID: 35706668 DOI: 10.6084/m9.figshare.c.6002280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
There is evidence that animal personality can affect sexual selection, with studies reporting that male behavioural types are associated with success during pre- and post-copulatory sexual selection. Given these links between personality and sexual traits, and the accumulating evidence that their expression can depend on an individual's dietary status (i.e. condition), a novel prediction is that changes in a male's diet should alter both the average expression of personality and sexual traits, and their covariance. We tested these predictions using the guppy Poecilia reticulata, a species previously shown to exhibit strong condition dependence in ejaculate traits and a positive correlation between sperm production and individual variation in boldness. Contrary to expectation, we found that dietary restriction-when administered in mature adult males-did not affect the expression of either behavioural (boldness and activity) or ejaculate traits, although we did find that males subjected to dietary stress exhibited a positive association between sperm velocity and boldness that was not apparent in the unrestricted diet group. This latter finding points to possible context-dependent patterns of covariance between sexually selected traits and personalities, which may have implications for patterns of selection and evolutionary processes under fluctuating environmental conditions.
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Affiliation(s)
- Edward Galluccio
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
| | - Rowan A Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
| | - Alastair Wilson
- Centre for Ecology and Evolution, University of Exeter, Cornwall Campus, Penryn, UK
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
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6
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Galluccio E, Lymbery RA, Wilson A, Evans JP. Personality, sperm traits and a test for their combined dependence on male condition in guppies. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220269. [PMID: 35706668 PMCID: PMC9156929 DOI: 10.1098/rsos.220269] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/11/2022] [Indexed: 05/03/2023]
Abstract
There is evidence that animal personality can affect sexual selection, with studies reporting that male behavioural types are associated with success during pre- and post-copulatory sexual selection. Given these links between personality and sexual traits, and the accumulating evidence that their expression can depend on an individual's dietary status (i.e. condition), a novel prediction is that changes in a male's diet should alter both the average expression of personality and sexual traits, and their covariance. We tested these predictions using the guppy Poecilia reticulata, a species previously shown to exhibit strong condition dependence in ejaculate traits and a positive correlation between sperm production and individual variation in boldness. Contrary to expectation, we found that dietary restriction-when administered in mature adult males-did not affect the expression of either behavioural (boldness and activity) or ejaculate traits, although we did find that males subjected to dietary stress exhibited a positive association between sperm velocity and boldness that was not apparent in the unrestricted diet group. This latter finding points to possible context-dependent patterns of covariance between sexually selected traits and personalities, which may have implications for patterns of selection and evolutionary processes under fluctuating environmental conditions.
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Affiliation(s)
- Edward Galluccio
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
| | - Rowan A. Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
| | - Alastair Wilson
- Centre for Ecology and Evolution, University of Exeter, Cornwall Campus, Penryn, UK
| | - Jonathan P. Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 Western Australia, Australia
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7
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Strategic adjustment of ejaculate quality in response to variation of the socio-sexual environment. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03032-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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8
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Fitzpatrick JL. Sperm competition and fertilization mode in fishes. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200074. [PMID: 33070731 PMCID: PMC7661453 DOI: 10.1098/rstb.2020.0074] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2020] [Indexed: 12/18/2022] Open
Abstract
Sperm competition is a powerful selective force that has shaped sexual traits throughout animal evolution. Yet, how fertilization mode (i.e. external versus internal fertilization) influences the scope and potential for sperm competition to act on ejaculates remains unclear. Here, I examine how fertilization mode shapes ejaculatory responses to sperm competition in fishes, a diverse group that constitute the majority of vertebrate biological diversity. Fishes are an ideal group for this examination because they exhibit a wide range of reproductive behaviours and an unparalleled number of transitions in fertilization mode compared to any other vertebrate group. Drawing on data from cartilaginous and bony fishes, I first show that rates of multiple paternity are higher in internally than externally fertilizing fishes, contrary to the prevailing expectation. I then summarize how sperm competition acts on sperm number and quality in internally and externally fertilizing fishes, highlighting where theoretical predictions differ between these groups. Differences in how ejaculates respond to sperm competition between fertilization modes are most apparent when considering sperm size and swimming performance. Clarifying how fertilization mode influences evolutionary responses in ejaculates will inform our understanding of ejaculate evolution across the animal tree of life. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- John L. Fitzpatrick
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, Stockholm 10691, Sweden
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9
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Trade-offs of strategic sperm adjustments and their consequences under phenotype–environment mismatches in guppies. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.06.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Spagopoulou F, Vega-Trejo R, Head ML, Jennions MD. Shifts in Reproductive Investment in Response to Competitors Lower Male Reproductive Success. Am Nat 2020; 196:355-368. [PMID: 32813996 DOI: 10.1086/709821] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractIn many species, males exhibit phenotypic plasticity in sexually selected traits when exposed to social cues about the intensity of sexual competition. To date, however, few studies have tested how this plasticity affects male reproductive success. We initially tested whether male mosquitofish, Gambusia holbrooki (Poeciliidae), change their investment in traits under pre- and postcopulatory sexual selection depending on the social environment. For a full spermatogenesis cycle, focal males were exposed to visual and chemical cues of rivals that were either present (competitive treatment) or absent (control). Males from the competitive treatment had significantly slower-swimming sperm but did not differ in sperm count from control males. When two males competed for a female, competitive treatment males also made significantly fewer copulation attempts and courtship displays than control males. Further, paternity analysis of 708 offspring from 148 potential sires, testing whether these changes in reproductive traits affected male reproductive success, showed that males previously exposed to cues about the presence of rivals sired significantly fewer offspring when competing with a control male. We discuss several possible explanations for these unusual findings.
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11
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Liu J, Zhang Y, Zheng X, He XZ, Wang Q. Combined cues of male competition influence spermatozoal investment in a moth. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Junyan Liu
- School of Agriculture and Environment Massey University Palmerston North New Zealand
| | - Yujing Zhang
- Guangxi Key Laboratory of Agric‐Environment and Agric‐Products Safety National Demonstration Center for Experimental Plant Science Education College of Agriculture Guangxi University Nanning China
| | - Xia‐Lin Zheng
- Guangxi Key Laboratory of Agric‐Environment and Agric‐Products Safety National Demonstration Center for Experimental Plant Science Education College of Agriculture Guangxi University Nanning China
| | - Xiong Z. He
- School of Agriculture and Environment Massey University Palmerston North New Zealand
| | - Qiao Wang
- School of Agriculture and Environment Massey University Palmerston North New Zealand
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12
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Chung MHJ, Jennions MD, Fox RJ. Novel ablation technique shows no sperm priming response by male eastern mosquitofish to cues of female availability. Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2779-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Vega‐Trejo R, Fox RJ, Iglesias‐Carrasco M, Head ML, Jennions MD. The effects of male age, sperm age and mating history on ejaculate senescence. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13305] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Regina Vega‐Trejo
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
- Department of Zoology Stockholm University Stockholm Sweden
| | - Rebecca J. Fox
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
| | - Maider Iglesias‐Carrasco
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
| | - Megan L. Head
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
| | - Michael D. Jennions
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
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14
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Bertram MG, Ecker TE, Wong BBM, O'Bryan MK, Baumgartner JB, Martin JM, Saaristo M. The antidepressant fluoxetine alters mechanisms of pre- and post-copulatory sexual selection in the eastern mosquitofish (Gambusia holbrooki). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 238:238-247. [PMID: 29567445 DOI: 10.1016/j.envpol.2018.03.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/08/2018] [Accepted: 03/04/2018] [Indexed: 06/08/2023]
Abstract
Contamination of aquatic habitats with pharmaceuticals is a major environmental concern. Recent studies have detected pharmaceutical pollutants in a wide array of ecosystems and organisms, with many of these contaminants being highly resistant to biodegradation and capable of eliciting sub-lethal effects in non-target species. One such pollutant is fluoxetine, a widely prescribed antidepressant, which is frequently detected in surface waters globally and can alter physiology and behaviour in aquatic organisms. Despite this, relatively little is known about the potential for fluoxetine to disrupt mechanisms of sexual selection. Here, we investigate the impacts of 30-day exposure to two environmentally realistic levels of fluoxetine (low and high) on mechanisms of pre- and post-copulatory sexual selection in the eastern mosquitofish (Gambusia holbrooki). We tested 1) male mating behaviour in the absence or presence of a competitor male, and 2) sperm quality and quantity. We found that high-fluoxetine exposure increased male copulatory behaviour in the absence of a competitor, while no effect was detected under male-male competition. Further, fluoxetine exposure at both concentrations increased total sperm count relative to males from the control group, while no significant change in sperm quality was observed. Lastly, low-fluoxetine males showed a significant reduction in condition index (mass relative to length). Our study is the first to show altered mechanisms of both pre- and post-copulatory sexual selection in an aquatic species resulting from environmentally realistic fluoxetine exposure, highlighting the capacity of pharmaceutical pollution to interfere with sensitive reproductive processes in wildlife.
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Affiliation(s)
- Michael G Bertram
- School of Biological Sciences, Monash University, Victoria, Australia.
| | - Tiarne E Ecker
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Bob B M Wong
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Moira K O'Bryan
- School of Biological Sciences, Monash University, Victoria, Australia; The Development and Stem Cells Program of Monash Biomedicine Discovery Institute and the Department of Anatomy and Developmental Biology, Monash University, Victoria, Australia
| | - John B Baumgartner
- Department of Biological Sciences, Macquarie University, New South Wales, Australia
| | - Jake M Martin
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Minna Saaristo
- School of Biological Sciences, Monash University, Victoria, Australia; Department of Biosciences, Åbo Akademi University, Turku, Finland
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15
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Grueber CE, Fitzpatrick JL, Devigili A, Gasparini C, Ramnarine IW, Evans JP. Population demography and heterozygosity-fitness correlations in natural guppy populations: An examination using sexually selected fitness traits. Mol Ecol 2017; 26:4631-4643. [PMID: 28734054 DOI: 10.1111/mec.14243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 06/12/2017] [Indexed: 11/30/2022]
Abstract
Heterozygosity-fitness correlations (HFCs) have been examined in a wide diversity of contexts, and the results are often used to infer the role of inbreeding in natural populations. Although population demography, reflected in population-level genetic parameters such as allelic diversity or identity disequilibrium, is expected to play a role in the emergence and detectability of HFCs, direct comparisons of variation in HFCs across many populations of the same species, with different genetic histories, are rare. Here, we examined the relationship between individual microsatellite heterozygosity and a range of sexually selected traits in 660 male guppies from 22 natural populations in Trinidad. Similar to previous studies, observed HFCs were weak overall. However, variation in HFCs among populations was high for some traits (although these variances were not statistically different from zero). Population-level genetic parameters, specifically genetic diversity levels (number of alleles, observed/expected heterozygosity) and measures of identity disequilibrium (g2 and heterozygosity-heterozygosity correlations), were not associated with variation in population-level HFCs. This latter result indicates that these metrics do not necessarily provide a reliable predictor of HFC effect sizes across populations. Importantly, diversity and identity disequilibrium statistics were not correlated, providing empirical evidence that these metrics capture different essential characteristics of populations. A complex genetic architecture likely underpins multiple fitness traits, including those associated with male fitness, which may have reduced our ability to detect HFCs in guppy populations. Further advances in this field would benefit from additional research to determine the demographic contexts in which HFCs are most likely to occur.
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Affiliation(s)
- Catherine E Grueber
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, NSW, Australia.,San Diego Zoo Global, San Diego, CA, USA.,Department of Zoology, University of Otago, Dunedin, New Zealand
| | - John L Fitzpatrick
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
| | - Alessandro Devigili
- Department of Zoology, Stockholm University, Stockholm, Sweden.,Department of Biology, University of Padova, Padua, Italy
| | - Clelia Gasparini
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
| | - Indar W Ramnarine
- Department of Life Sciences, University of the West Indies, St Augustine, Trinidad and Tobago
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
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16
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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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17
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Devigili A, Evans JP, Di Nisio A, Pilastro A. Multivariate selection drives concordant patterns of pre- and postcopulatory sexual selection in a livebearing fish. Nat Commun 2015; 6:8291. [PMID: 26369735 PMCID: PMC4579849 DOI: 10.1038/ncomms9291] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 08/06/2015] [Indexed: 11/18/2022] Open
Abstract
In many species, females mate with multiple partners, meaning that sexual selection on male traits operates across a spectrum that encompasses the competition for mates (that is, before mating) and fertilizations (after mating). Despite being inextricably linked, pre- and postcopulatory sexual selection are typically studied independently, and we know almost nothing about how sexual selection operates across this divide. Here we bridge this knowledge gap using the livebearing fish Poecilia reticulata. We show that both selective episodes, as well as their covariance, explain a significant component of variance in male reproductive fitness. Moreover, linear and nonlinear selection simultaneously act on pre- and postcopulatory traits, and interact to generate multiple phenotypes with similar fitness. In species in which females mate with multiple partners, sexual selection acts on male traits involved in mating and fertilization. Here, the authors show that selection acting before and after mating explains a significant component of variance in male reproductive fitness in a livebearing fish.
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Affiliation(s)
- Alessandro Devigili
- Department of Biology, University of Padova, via Ugo Bassi 58/b, 35131 Padua, Italy
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, 35 Stirling Highway, Western Australia, 6009 Crawley, Australia
| | - Andrea Di Nisio
- Department of Biology, University of Padova, via Ugo Bassi 58/b, 35131 Padua, Italy
| | - Andrea Pilastro
- Department of Biology, University of Padova, via Ugo Bassi 58/b, 35131 Padua, Italy
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18
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Devigili A, Doldán-Martelli V, Pilastro A. Exploring simultaneous allocation to mating effort, sperm production, and body growth in male guppies. Behav Ecol 2015. [DOI: 10.1093/beheco/arv067] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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19
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20
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Rahman MM, Gasparini C, Turchini GM, Evans JP. Testing the interactive effects of carotenoids and polyunsaturated fatty acids on ejaculate traits in the guppy Poecilia reticulata (Pisces: Poeciliidae). JOURNAL OF FISH BIOLOGY 2015; 86:1638-1643. [PMID: 25816838 DOI: 10.1111/jfb.12661] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 01/31/2015] [Indexed: 06/04/2023]
Abstract
Using the polyandrous livebearing guppy Poecilia reticulata, this study revealed no main effects of carotenoids in the diet on ejaculate traits, but significant main effects of polyunsaturated fatty acids (PUFAs) on sperm viability and weak but significant interacting effects of both nutrients on sperm length. Collectively, these findings not only add evidence that PUFAs are critical determinants of sperm quality, but also provide tentative evidence that for some traits these effects may be moderated by carotenoid intake.
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Affiliation(s)
- M M Rahman
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, WA 6009, Australia
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Evans JP, Rahman MM, Gasparini C. Genotype-by-environment interactions underlie the expression of pre- and post-copulatory sexually selected traits in guppies. J Evol Biol 2015; 28:959-72. [DOI: 10.1111/jeb.12627] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/20/2015] [Accepted: 03/20/2015] [Indexed: 11/28/2022]
Affiliation(s)
- J. P. Evans
- Centre for Evolutionary Biology; School of Animal Biology (M092); Crawley WA Australia
| | - M. M. Rahman
- Centre for Evolutionary Biology; School of Animal Biology (M092); Crawley WA Australia
| | - C. Gasparini
- Centre for Evolutionary Biology; School of Animal Biology (M092); Crawley WA Australia
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22
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Fitzpatrick JL, Evans JP. Postcopulatory inbreeding avoidance in guppies. J Evol Biol 2014; 27:2585-94. [PMID: 25387854 DOI: 10.1111/jeb.12545] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/22/2014] [Accepted: 10/23/2014] [Indexed: 01/18/2023]
Abstract
In many species, the negative fitness effects of inbreeding have facilitated the evolution of a wide range of inbreeding avoidance mechanisms. Although avoidance mechanisms operating prior to mating are well documented, evidence for postcopulatory mechanisms of inbreeding avoidance remain scarce. Here, we examine the potential for paternity biases to favour unrelated males when their sperm compete for fertilizations though postcopulatory inbreeding avoidance mechanisms in the guppy, Poecilia reticulata. To test this possibility, we used a series of artificial inseminations to deliver an equal number of sperm from a related (either full sibling or half sibling) and unrelated male to a female while statistically controlling for differences in sperm quality between rival ejaculates. In this way, we were able to focus exclusively on postcopulatory mechanisms of inbreeding avoidance and account for differences in sperm competitiveness between rival males. Under these carefully controlled conditions, we report a significant bias in paternity towards unrelated males, although this effect was only apparent when the related male was a full sibling. We also show that sperm competition generally favours males with highly viable sperm and thus that some variance in sperm competitiveness can be attributed to difference in sperm quality. Our findings for postcopulatory inbreeding avoidance are consistent with prior work on guppies, revealing that sperm competition success declines linearly with the level of relatedness, but also that such effects are only apparent at relatedness levels of full siblings or higher. These findings reveal that postcopulatory processes alone can facilitate inbreeding avoidance.
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Affiliation(s)
- J L Fitzpatrick
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK; Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, WA, Australia
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23
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O'Dea RE, Jennions MD, Head ML. Male body size and condition affects sperm number and production rates in mosquitofish, Gambusia holbrooki. J Evol Biol 2014; 27:2739-44. [PMID: 25403851 DOI: 10.1111/jeb.12534] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 10/10/2014] [Accepted: 10/20/2014] [Indexed: 11/30/2022]
Abstract
Sperm number is an important predictor of paternity when there is sperm competition. Sperm number is often measured as maximum sperm reserves, but in species where mating is frequent, males will often be replenishing their reserves. Thus, variation in how quickly males can produce sperm is likely to be important in determining male success in sperm competition. Despite this, little is known about how male size, body condition or diet affects sperm production rates. We counted sperm number in large and small Gambusia holbrooki (eastern mosquitofish) after 3 weeks on either a high or low food diet. Sperm number was significantly higher in both larger males and in well-fed males. We then stripped ejaculates again either 1, 2, 3, 4 or 5 days later to investigate subsequent sperm production. The rate of sperm replenishment was influenced by an interaction between size and diet. Large, well-fed males had consistently high levels of sperm available over the 5 days (i.e. rapid replenishment), whereas small poorly fed males showed consistently low levels of sperm availability over the 5 days (i.e. slow replenishment). In contrast, large, poorly fed and small, well-fed males increased their sperm numbers over the first 3 days (i.e. intermediate replenishment). Our study highlights that when mating is frequent and sperm competition is high, size and condition dependence of maximal sperm number and of sperm production rate might both contribute to variation in male reproductive success.
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Affiliation(s)
- R E O'Dea
- Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT, Australia
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24
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The expression of pre- and postcopulatory sexually selected traits reflects levels of dietary stress in guppies. PLoS One 2014; 9:e105856. [PMID: 25170940 PMCID: PMC4149491 DOI: 10.1371/journal.pone.0105856] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 07/22/2014] [Indexed: 11/21/2022] Open
Abstract
Environmental and ecological conditions can shape the evolution of life history traits in many animals. Among such factors, food or nutrition availability can play an important evolutionary role in moderating an animal's life history traits, particularly sexually selected traits. Here, we test whether diet quantity and/or composition in the form of omega-3 long chain polyunsaturated fatty acids (here termed ‘n3LC’) influence the expression of pre- and postcopulatory traits in the guppy (Poecilia reticulata), a livebearing poeciliid fish. We assigned males haphazardly to one of two experimental diets supplemented with n3LC, and each of these diet treatments was further divided into two diet ‘quantity’ treatments. Our experimental design therefore explored the main and interacting effects of two factors (n3LC content and diet quantity) on the expression of precopulatory (sexual behaviour and sexual ornamentation, including the size, number and spectral properties of colour spots) and postcopulatory (the velocity, viability, number and length of sperm) sexually selected traits. Our study revealed that diet quantity had significant effects on most of the pre- and postcopulatory traits, while n3LC manipulation had a significant effect on sperm traits and in particular on sperm viability. Our analyses also revealed interacting effects of diet quantity and n3LC levels on courtship displays, and the area of orange and iridescent colour spots in the males’ colour patterns. We also confirmed that our dietary manipulations of n3LC resulted in the differential uptake of n3LC in body and testes tissues in the different n3LC groups. This study reveals the effects of diet quantity and n3LC on behavioural, ornamental and ejaculate traits in P. reticulata and underscores the likely role that diet plays in maintaining the high variability in these condition-dependent sexual traits.
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25
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Barrett LT, Evans JP, Gasparini C. The effects of perceived mating opportunities on patterns of reproductive investment by male guppies. PLoS One 2014; 9:e93780. [PMID: 24705713 PMCID: PMC3976321 DOI: 10.1371/journal.pone.0093780] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/07/2014] [Indexed: 11/19/2022] Open
Abstract
Males pay considerable reproductive costs in acquiring mates (precopulatory sexual selection) and in producing ejaculates that are effective at fertilising eggs in the presence of competing ejaculates (postcopulatory sexual selection). Given these costs, males must balance their reproductive investment in a given mating to optimise their future reproductive potential. Males are therefore expected to invest in reproduction prudently according to the likelihood of obtaining future matings. In this study we tested this prediction by determining whether male reproductive investment varies with expected future mating opportunities, which were experimentally manipulated by visually exposing male guppies (Poecilia reticulata) to high or low numbers of females in the absence of competing males. Our experiment did not reveal consistent effects of perceived future mating opportunity on either precopulatory (male mate choice and mating behaviour) or postcopulatory (sperm quality and quantity) investment. However, we did find that male size and female availability interacted to influence mating behaviour; large males visually deprived of females during the treatment phase became more choosy and showed greater interest in their preferred female than those given continuous visual access to females. Overall, our results suggest males tailor pre- rather than postcopulatory traits according to local female availability, but critically, these effects depend on male size.
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Affiliation(s)
- Luke T. Barrett
- Centre for Evolutionary Biology, School of Animal Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Jonathan P. Evans
- Centre for Evolutionary Biology, School of Animal Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Clelia Gasparini
- Centre for Evolutionary Biology, School of Animal Biology, The University of Western Australia, Crawley, Western Australia, Australia
- * E-mail:
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26
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27
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Simpson JL, Humphries S, Evans JP, Simmons LW, Fitzpatrick JL. Relationships between sperm length and speed differ among three internally and three externally fertilizing species. Evolution 2013; 68:92-104. [PMID: 24224469 DOI: 10.1111/evo.12199] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 06/04/2013] [Indexed: 11/30/2022]
Abstract
It is often assumed that longer sperm, by virtue of their increased swimming speed, have a fertilization advantage over shorter sperm when in competition to fertilize eggs. However, there is surprisingly little evidence for a positive correlation between sperm length and speed. Here we use an approach that accounts for within-male variation in sperm traits to examine the relationships between sperm length and sperm speed across a broad range of species, including three internally fertilizing species and three externally fertilizing species. Our results reveal that correlations between sperm size and speed are indeed present and possibly more common than currently thought. However, the direction of the correlations between sperm length and speed, which are more prevalent within a male's ejaculate than among males, were influenced by fertilization mode in contrasting and unexpected ways. Broadly, the patterns revealed that in externally fertilizing species sperm with longer flagellum and shorter heads relative to their flagellum swam faster, whereas in internally fertilizing species sperm with shorter flagellum and longer heads relative to their flagellum swam faster. We discuss these results in light of sperm competition theory and contrast the intraspecific patterns observed in this study with macroevolutionary patterns of sperm evolution reported elsewhere.
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Affiliation(s)
- Julia L Simpson
- Physical Ecology Group, School of Biological, Biomedical and Environmental Sciences, The University of Hull, Kingston-upon-Hull, HU6 7RX, United Kingdom
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28
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Rahman MM, Kelley JL, Evans JP. Condition-dependent expression of pre- and postcopulatory sexual traits in guppies. Ecol Evol 2013; 3:2197-213. [PMID: 23919162 PMCID: PMC3728957 DOI: 10.1002/ece3.632] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 05/09/2013] [Accepted: 05/10/2013] [Indexed: 02/03/2023] Open
Abstract
Female choice can impose persistent directional selection on male sexually selected traits, yet such traits often exhibit high levels of phenotypic variation. One explanation for this paradox is that if sexually selected traits are costly, only the fittest males are able to acquire and allocate the resources required for their expression. Furthermore, because male condition is dependent on resource allocation, condition dependence in sexual traits is expected to underlie trade-offs between reproduction and other life-history functions. In this study we test these ideas by experimentally manipulating diet quality (carotenoid levels) and quantity in the guppy (Poecilia reticulata), a livebearing freshwater fish that is an important model for understanding relationships between pre- and post-copulatory sexually selected traits. Specifically, we test for condition dependence in the expression of pre- and postcopulatory sexual traits (behavior, ornamentation, sperm traits) and determine whether diet manipulation mediates relationships among these traits. Consistent with prior work we found a significant effect of diet quantity on the expression of both pre- and postcopulatory male traits; diet-restricted males performed fewer sexual behaviors and exhibited significant reductions in color ornamentation, sperm quality, sperm number, and sperm length than those fed ad libitum. However, contrary to our expectations, we found no significant effect of carotenoid manipulation on the expression of any of these traits, and no evidence for a trade-off in resource allocation between pre- and postcopulatory episodes of sexual selection. Our results further underscore the sensitivity of behavioral, ornamental, and ejaculate traits to dietary stress, and highlight the important role of condition dependence in maintaining the high variability in male sexual traits.
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Affiliation(s)
- Md Moshiur Rahman
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia Crawley, 6009, Western Australia, Australia
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29
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Gasparini C, Evans JP. Ovarian fluid mediates the temporal decline in sperm viability in a fish with sperm storage. PLoS One 2013; 8:e64431. [PMID: 23691216 PMCID: PMC3653924 DOI: 10.1371/journal.pone.0064431] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 04/15/2013] [Indexed: 01/12/2023] Open
Abstract
A loss of sperm viability and functionality during sperm transfer and storage within the female reproductive tract can have important fitness implications by disrupting fertilization and impairing offspring development and survival. Consequently, mechanisms that mitigate the temporal decline in sperm function are likely to be important targets of selection. In many species, ovarian fluid is known to regulate and maintain sperm quality. In this paper, we use the guppy Poecilia reticulata, a highly polyandrous freshwater fish exhibiting internal fertilization and sperm storage, to determine whether ovarian fluid (OF) influences the decline in sperm viability (the proportion of live sperm in the ejaculate) over time and whether any observed effects depend on male sexual ornamentation. To address these questions we used a paired experimental design in which ejaculates from individual males were tested in vitro both in presence and absence of OF. Our results revealed that the temporal decline in sperm viability was significantly reduced in the presence of OF compared to a saline control. This finding raises the intriguing possibility that OF may play a role in mediating the decline in sperm quality due to the deleterious effects of sperm ageing, although other possible explanations for this observation are discussed. Interestingly, we also show that the age-related decline in sperm viability was contingent on male sexual ornamentation; males with relatively high levels of iridescence (indicating higher sexual attractiveness) exhibited a more pronounced decline in sperm viability over time than their less ornamented counterparts. This latter finding offers possible insights into the functional basis for the previously observed trade-off between these key components of pre- and postcopulatory sexual selection.
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Affiliation(s)
- Clelia Gasparini
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, Australia.
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30
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Breckels RD, Neff BD. The effects of elevated temperature on the sexual traits, immunology and survivorship of a tropical ectotherm. ACTA ACUST UNITED AC 2013; 216:2658-64. [PMID: 23531818 DOI: 10.1242/jeb.084962] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In 2007, the Intergovernmental Panel on Climate Change projected an average global air temperature increase of 1.1-6.4°C by the end of the 21st century. Although the tropics are predicted to experience less extreme temperature increases than regions of higher latitude, tropical ectotherms live close to their thermal limits, and are thus particularly vulnerable to increases in temperature. In this study, we examined how predicted patterns of global warming will affect survival and sexual traits in the Trinidadian guppy (Poecilia reticulata). Guppies were exposed from birth to one of four temperature treatments: 23, 25 (control), 28 or 30°C. We measured brood survival and, at sexual maturity, male ornamentation, sperm traits and immune response. Our results show that increases in temperature result in guppies that have shorter, slower sperm but that there is an optimum temperature for ornamental hue at 28°C. Given the importance of sperm quality for reproduction, these results suggest population viability could be affected by warming. However, we found no difference in brood survival or immune response to a novel antigen across the treatments, indicating that survival may not be as vulnerable as previously thought. Overall, our data suggest that male sexual traits, and in particular sperm performance, are more sensitive than survival to a warming environment.
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Affiliation(s)
- Ross D Breckels
- Department of Biology, University of Western Ontario, London, ON, Canada, N6A 5B7
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31
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Devigili A, Kelley JL, Pilastro A, Evans JP. Expression of pre- and postcopulatory traits under different dietary conditions in guppies. Behav Ecol 2012. [DOI: 10.1093/beheco/ars204] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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32
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Shifferman EM. It's all in your head: the role of quantity estimation in sperm competition. Proc Biol Sci 2012; 279:833-40. [PMID: 22171084 PMCID: PMC3259941 DOI: 10.1098/rspb.2011.2256] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 11/25/2011] [Indexed: 11/12/2022] Open
Abstract
The study of animal cognition has provided valuable data throughout the years, yet its reliance on laboratory work leaves some open questions. The main question is whether animals employ cognition in daily decision-making. The following discussion uses sperm competition (SC) as a test case for demonstrating the effect of cognition on routine choices, in this case, sexual selection. Cognition is manifested here by males' ability to represent the number of rivals competing with them. I claim that response to SC is driven by quantity estimation and the ability to assess competition magnitude cognitively. Hence, cognition can determine males' response to SC, and consequentially it can be selected within this context. This supports the argument that cognition constitutes an integral part of an individual's toolbox in solving real-life problems, and shows that physical and behavioural phenomena can expose cognition to selection and facilitate its evolution.
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Affiliation(s)
- Eran M Shifferman
- Konrad Lorenz Institute for Evolution and Cognition Research, Adolf Lorenz Gasse 2, 3422 Altenberg, Austria.
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33
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Kelly CD, Jennions MD. Sexual selection and sperm quantity: meta-analyses of strategic ejaculation. Biol Rev Camb Philos Soc 2011; 86:863-84. [PMID: 21414127 DOI: 10.1111/j.1469-185x.2011.00175.x] [Citation(s) in RCA: 214] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Clint D Kelly
- Department of Ecology, Evolution & Organismal Biology, Iowa State University, Ames, USA.
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34
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Sperm number and velocity affect sperm competition success in the guppy (Poecilia reticulata). Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1085-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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35
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Patterns of genetic variation and covariation in ejaculate traits reveal potential evolutionary constraints in guppies. Heredity (Edinb) 2010; 106:869-75. [PMID: 20959863 DOI: 10.1038/hdy.2010.130] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ejaculates comprise multiple and potentially interacting traits that determine male fertility and sperm competitiveness. Consequently, selection on these traits is likely to be intense, but the efficacy of selection will depend critically on patterns of genetic variation and covariation underlying their expression. In this study, I provide a prospective quantitative genetic analysis of ejaculate traits in the guppy Poecilia reticulata, a highly promiscuous live-bearing fish. I used a standard paternal half-sibling breeding design to characterize patterns of genetic (co)variation in components of sperm length and in vitro sperm performance. All traits exhibited high levels of phenotypic and additive genetic variation, and in several cases, patterns of genetic variation was consistent with Y-linkage. There were also highly significant negative genetic correlations between the various measures of sperm length and sperm performance. In particular, the length of the sperm's midpiece was strongly, negatively and genetically correlated with sperm's swimming velocity-an important determinant of sperm competitiveness in this and other species. Other components of sperm length, including the flagellum and head, were independently and negatively genetically correlated with the proportion of live sperm in the ejaculate (sperm viability). Whether these relationships represent evolutionary trade-offs depends on the precise relationships between these traits and competitive fertilization rates, which have yet to be fully resolved in this (and indeed most) species. Nevertheless, these prospective analyses point to potential constraints on ejaculate evolution and may explain the high level of phenotypic variability in ejaculate traits in this species.
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36
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JORDAN LA, BROOKS RC. The lifetime costs of increased male reproductive effort: courtship, copulation and the Coolidge effect. J Evol Biol 2010; 23:2403-9. [DOI: 10.1111/j.1420-9101.2010.02104.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Smith CC, Ryan MJ. Evolution of sperm quality but not quantity in the internally fertilized fish Xiphophorus nigrensis. J Evol Biol 2010; 23:1759-71. [PMID: 20626545 DOI: 10.1111/j.1420-9101.2010.02041.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Species with alternative reproductive strategies are characterized by discrete differences among males in suites of traits related to competition for fertilizations. Models predict sneaker males should allocate more resources to their ejaculates because they experience sperm competition more frequently and often occupy a disfavoured 'role' owing to subordinance in intramale competition and female preferences for larger males. We examined whether sperm number and quality differed between male strategies in the internally fertilized fish Xiphophorus nigrensis and explored the relationship between sperm morphology and performance. We found sneaker males had similar testes sizes compared to courting males but ejaculates with both more viable and longer lived sperm. Sneaker sperm also had longer midpieces, which was positively correlated with both velocity and longevity. Our study suggests that the evolution of sperm quantity and quality can be decoupled and that the sperm morphology is likely to play an important role in mediating sperm competition through its effects on sperm performance.
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Affiliation(s)
- C C Smith
- University of Texas at Austin, Section of Integrative Biology, Austin, TX 78712, USA.
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38
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Evans JP. Quantitative genetic evidence that males trade attractiveness for ejaculate quality in guppies. Proc Biol Sci 2010; 277:3195-201. [PMID: 20504807 DOI: 10.1098/rspb.2010.0826] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Polyandry, where females mate with multiple males, means that a male's reproductive success will depend both on his ability to acquire mates and the ability of his sperm to compete effectively for fertilizations. But, how do males partition their reproductive investment between these two episodes of selection? Theory predicts that increases in ejaculate investment will come at a cost to investment in other reproductive traits. Although evidence revealing such trade-offs is accumulating, we know little about their genetic basis. Here, I report patterns of genetic (co)variation for a range of traits subject to pre- and post-copulatory sexual selection in the guppy Poecilia reticulata, a promiscuous livebearing fish in which males alternate between courtship and sneak matings to obtain copulations. The analyses of genetic variation and covariation for these behaviours revealed a strong genetic predisposition for one tactic over the other. Both mating tactics were also strongly genetically integrated with the level of sexual ornamentation and ejaculate quality. Males that predominantly performed sneak matings were less ornamented but had faster swimming sperm than those that predominantly used courtship. These patterns of genetic variation and covariation reveal potential evolutionary constraints on the direction of selection of pre- and post-copulatory traits, and support sperm competition theory by revealing a trade-off between sexual attractiveness and investment in ejaculates.
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Affiliation(s)
- Jonathan P Evans
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Nedlands, Western Australia, Australia.
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39
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Gasparini C, Peretti AV, Pilastro A. Female presence influences sperm velocity in the guppy. Biol Lett 2009; 5:792-4. [PMID: 19656863 DOI: 10.1098/rsbl.2009.0413] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As sperm production is costly, males are expected to strategically allocate resources to sperm production according to mating opportunities. While sperm number adjustments have been reported in several taxa, only a few studies investigated whether sperm quality shows adaptive plasticity as well. We tested this prediction in the guppy, Poecilia reticulata. A total of 46 males were initially stripped of all retrievable sperm before being randomly allocated to one of two treatments simulating different levels of mating opportunities (visual contact with females or female deprived). After 3 days, males were stripped and sperm velocity was assayed using Computer Assisted Sperm Analysis. Males in the presence of females produced significantly faster sperm than their counterparts. Implications for the evolution of this ejaculate plasticity in the light of results of sperm competition studies are discussed.
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Affiliation(s)
- Clelia Gasparini
- Dipartimento di Biologia, Università di Padova, via Ugo Bassi 58/B 35131, Padova, Italy.
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