1
|
André GI, Firman RC, Simmons LW. The effect of genital stimulation on competitive fertilization success in house mice. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.05.015] [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]
|
2
|
Churchill ER, Dytham C, Bridle JR, Thom MDF. Social and physical environment independently affect oviposition decisions in Drosophila. Behav Ecol 2021; 32:1391-1399. [PMID: 34949961 PMCID: PMC8691557 DOI: 10.1093/beheco/arab105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/23/2021] [Accepted: 09/07/2021] [Indexed: 11/29/2022] Open
Abstract
In response to environmental stimuli, including variation in the presence of conspecifics, genotypes show highly plastic responses in behavioral and physiological traits influencing reproduction. Although extensively documented in males, such female responses are rather less studied. We expect females to be highly responsive to environmental variation and to differentially allocate resources to increase offspring fitness, given the major contribution of mothers to offspring number, size, and developmental conditions. Using Drosophila melanogaster, we (a) manipulate exposure to conspecific females, which mothers could use to anticipate the number of potential mates and larval density, and; (b) test how this interacts with the spatial distribution of potential oviposition sites, with females from higher densities expected to prefer clustered resources that can support a larger number of larvae. We found that high density females were slower to start copulating and reduced their copulation duration, the opposite effect to that observed in males. There was a parallel, perhaps related, effect on egg production: females previously housed in groups laid fewer eggs than those housed in solitude. Resource patchiness also influenced oviposition behavior: females preferred aggregated substrate, which attracted more females to lay eggs. However, we found no interaction between prior housing conditions and resource patchiness, indicating that females did not perceive the value of different resource distributions differently when exposed to environments that could signal expected levels of larval competition. We show that, although exposure to consexual competition changes copulatory behaviors of females, the distribution of oviposition resources has a greater effect on oviposition decisions.
Collapse
Affiliation(s)
- Emily R Churchill
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | | | - Jon R Bridle
- Department for Genetics, Evolution and Environment, University College London, London, UK
| | - Michael D F Thom
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| |
Collapse
|
3
|
|
4
|
Firman RC. Of mice and women: advances in mammalian sperm competition with a focus on the female perspective. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200082. [PMID: 33070720 DOI: 10.1098/rstb.2020.0082] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although initially lagging behind discoveries being made in other taxa, mammalian sperm competition is now a productive and advancing field of research. Sperm competition in mammals is not merely a 'sprint-race' between the gametes of rival males, but rather a race over hurdles; those hurdles being the anatomical and physiological barriers provided by the female reproductive tract, as well as the egg and its vestments. With this in mind, in this review, I discuss progress in the field while focusing on the female perspective. I highlight ways by which sperm competition can have positive effects on female reproductive success and discuss how competitive outcomes are not only owing to dynamics between the ejaculates of rival males, but also attributable to mechanisms by which female mammals bias paternity toward favourable sires. Drawing on examples across different species-from mice to humans-I provide an overview of the accumulated evidence which firmly establishes that sperm competition is a key selective force in the evolution of male traits and detail how females can respond to increased sperm competitiveness with increased egg resistance to fertilization. I also discuss evidence for facultative responses to the sperm competition environment observed within mammal species. Overall, this review identifies shortcomings in our understanding of the specific mechanisms by which female mammals 'select' sperm. More generally, this review demonstrates how, moving forward, mammals will continue to be effective animal models for studying both evolutionary and facultative responses to sperm competition. This article is part of the theme issue 'Fifty years of sperm competition'.
Collapse
Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| |
Collapse
|
5
|
Abstract
Promiscuous mating by females leads to competition between males for fertilization success. When fertilization is internal, this means that rival males’ sperm must compete within the female reproductive tract to reach the eggs. Males of diverse species deposit a mating plug during copulation, which is hypothesized to assist in the race for fertilization following multiple mating. Here, we tested this by using stable isotope labeling to discriminate the ejaculates of competing male voles in direct competition. This revealed that the mating plug simultaneously inhibits the sperm of rival males while promoting transport of a male’s own sperm, both of which are beneficial in the competition for fertilizations. Mating plugs are produced by many sexually reproducing animals and are hypothesized to promote male fertilization success under promiscuous mating. However, tests of this hypothesis have been constrained by an inability to discriminate ejaculates of different males in direct competition. Here, we use stable isotope labeling in vivo and proteomics to achieve this in a promiscuous rodent, Myodes glareolus. We show that, although the first male’s plug is usually dislodged, it can be retained throughout the second male’s copulation. Retained plugs did not completely block rival sperm but did significantly limit their numbers. Differences in the number of each male’s sperm progressing through the female reproductive tract were also explained by natural variation in the size of mating plugs and reproductive accessory glands from which major plug proteins originate. Relative sperm numbers in turn predicted the relative fertilization success of rival males. Our application of stable isotopes to label ejaculates resolves a longstanding debate by revealing how rodent mating plugs promote fertilization success under competitive conditions. This approach opens new opportunities to reveal cryptic mechanisms of postcopulatory sexual selection among diverse animal taxa.
Collapse
|
6
|
Firman RC, Garcia‐Gonzalez F, Simmons LW, André GI. A competitive environment influences sperm production, but not testes tissue composition, in house mice. J Evol Biol 2018; 31:1647-1654. [DOI: 10.1111/jeb.13360] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 07/26/2018] [Accepted: 07/28/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Renée C. Firman
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
| | - Francisco Garcia‐Gonzalez
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
- Estacion Biológica de Doñana CSIC Sevilla Spain
| | - Leigh W. Simmons
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
| | - Gonçalo I. André
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
| |
Collapse
|
7
|
André GI, Firman RC, Simmons LW. Phenotypic plasticity in genitalia: baculum shape responds to sperm competition risk in house mice. Proc Biol Sci 2018; 285:20181086. [PMID: 30051823 PMCID: PMC6053933 DOI: 10.1098/rspb.2018.1086] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 06/15/2018] [Indexed: 12/26/2022] Open
Abstract
Males are known to adjust their expenditure on testes growth and sperm production in response to sperm competition risk. Genital morphology can also contribute to competitive fertilization success but whether male genital morphology can respond plastically to the sperm competition environment has received little attention. Here, we exposed male house mice to two different sperm competition environments during their sexual development and quantified phenotypic plasticity in baculum morphology. The sperm competition environment generated plasticity in body growth. Males maturing under sperm competition risk were larger and heavier than males maturing under no sperm competition risk. We used a landmark-based geometric morphometric approach to measure baculum size and shape. Independent of variation in body size, males maintained under risk of sperm competition had a relatively thicker and more distally extended baculum bulb compared with males maintained under no sperm competition risk. Plasticity in baculum shape paralleled evolutionary responses to selection from sperm competition reported in previous studies of house mice. Our findings provide experimental evidence of socially mediated phenotypic plasticity in male genitalia.
Collapse
Affiliation(s)
- Gonçalo I André
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
| | - Renée C Firman
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
| |
Collapse
|
8
|
Perry JC, Joag R, Hosken DJ, Wedell N, Radwan J, Wigby S. Experimental evolution under hyper-promiscuity in Drosophila melanogaster. BMC Evol Biol 2016; 16:131. [PMID: 27311887 PMCID: PMC4910217 DOI: 10.1186/s12862-016-0699-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/05/2016] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The number of partners that individuals mate with over their lifetime is a defining feature of mating systems, and variation in mate number is thought to be a major driver of sexual evolution. Although previous research has investigated the evolutionary consequences of reductions in the number of mates, we know little about the costs and benefits of increased numbers of mates. Here, we use a genetic manipulation of mating frequency in Drosophila melanogaster to create a novel, highly promiscuous mating system. We generated D. melanogaster populations in which flies were deficient for the sex peptide receptor (SPR) gene - resulting in SPR- females that mated more frequently - and genetically-matched control populations, and allowed them to evolve for 55 generations. At several time-points during this experimental evolution, we assayed behavioural, morphological and transcriptional reproductive phenotypes expected to evolve in response to increased population mating frequencies. RESULTS We found that males from the high mating frequency SPR- populations evolved decreased ability to inhibit the receptivity of their mates and decreased copulation duration, in line with predictions of decreased per-mating investment with increased sperm competition. Unexpectedly, SPR- population males also evolved weakly increased sex peptide (SP) gene expression. Males from SPR- populations initially (i.e., before experimental evolution) exhibited more frequent courtship and faster time until mating relative to controls, but over evolutionary time these differences diminished or reversed. CONCLUSIONS In response to experimentally increased mating frequency, SPR- males evolved behavioural responses consistent with decreased male post-copulatory investment at each mating and decreased overall pre-copulatory performance. The trend towards increased SP gene expression might plausibly relate to functional differences in the two domains of the SP protein. Our study highlights the utility of genetic manipulations of animal social and sexual environments coupled with experimental evolution.
Collapse
Affiliation(s)
- Jennifer C Perry
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK. .,Jesus College, University of Oxford, Oxford, UK.
| | - Richa Joag
- University of Exeter, Penryn, UK.,Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | | | | | - Jacek Radwan
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Stuart Wigby
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK
| |
Collapse
|
9
|
Hulme-Beaman A, Dobney K, Cucchi T, Searle JB. An Ecological and Evolutionary Framework for Commensalism in Anthropogenic Environments. Trends Ecol Evol 2016; 31:633-645. [PMID: 27297117 DOI: 10.1016/j.tree.2016.05.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 05/01/2016] [Accepted: 05/03/2016] [Indexed: 10/21/2022]
Abstract
Commensalism within anthropogenic environments has not been extensively discussed, despite its impact on humans, and there is no formal framework for assessing this ecological relationship in its varied forms. Here, we examine commensalism in anthropogenic environments in detail, considering both ecological and evolutionary drivers. The many assumptions about commensalism and the nature of anthropogenic environments are discussed and we highlight dependency as a key attribute of anthropogenic commensals (anthrodependent taxa). We primarily focus on mammalian species in the anthropogenic-commensal niche, but the traits described and selective pressures presented are likely fundamental to many species engaged in intense commensal relationships with humans. Furthermore, we demonstrate that this largely understudied interaction represents an important opportunity to investigate evolutionary processes in rapidly changing environments.
Collapse
Affiliation(s)
- Ardern Hulme-Beaman
- Department of Archaeology, School of Geosciences, University of Aberdeen, St Mary's Building, Aberdeen, AB24 3UF, UK; Department of Archaeology, Classics and Egyptology, University of Liverpool, 12-14 Abercromby Square, Liverpool, L69 7WZ, UK.
| | - Keith Dobney
- Department of Archaeology, School of Geosciences, University of Aberdeen, St Mary's Building, Aberdeen, AB24 3UF, UK; Department of Archaeology, Classics and Egyptology, University of Liverpool, 12-14 Abercromby Square, Liverpool, L69 7WZ, UK
| | - Thomas Cucchi
- Department of Archaeology, School of Geosciences, University of Aberdeen, St Mary's Building, Aberdeen, AB24 3UF, UK; Muséum National d'Histoire Naturelle, CNRS UMR7209, Paris, France
| | - Jeremy B Searle
- Department of Ecology and Evolutionary Biology, Cornell University, Corson Hall, Ithaca, NY14853-2701, USA
| |
Collapse
|
10
|
|
11
|
Sutter A, Simmons LW, Lindholm AK, Firman RC. Function of copulatory plugs in house mice: mating behavior and paternity outcomes of rival males. Behav Ecol 2015. [DOI: 10.1093/beheco/arv138] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
|
12
|
Abraham S, Vera MT, Pérez-Staples D. Current Sperm Competition Determines Sperm Allocation in a Tephritid Fruit Fly. Ethology 2015. [DOI: 10.1111/eth.12355] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Solana Abraham
- Laboratorio de Investigaciones Ecoetológicas de Moscas de la Fruta y sus Enemigos Naturales (LIEMEN); PROIMI; Tucumán Argentina
- CONICET; Buenos Aires Argentina
| | - M. Teresa Vera
- CONICET; Buenos Aires Argentina
- Cátedra de Terapéutica Vegetal; Departamento de Sanidad Vegetal de la Facultad de Agronomía y Zootecnia de la UNT; Tucumán Argentina
| | | |
Collapse
|
13
|
Ben Chehida Y, Denis B, Claisse G, Joly D. [What the study of seminal fluid proteins in Drosophila tells us about the evolution of reproduction]. Med Sci (Paris) 2014; 30:651-7. [PMID: 25014456 DOI: 10.1051/medsci/20143006015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Decrease in male fertility observed in the past decades have involved sperm quantity and quality disorders. However, decrease in quality or quantity of seminal fluid may also trigger drastic reduction of female and also male fertility. The present paper documents on the composition of seminal fluid, the consequences on sperm cells and on the physiological and behavioral effects towards females. The work evidences the crucial role of seminal fluid in the postcopulatory interactions between the sexes and illustrates the selective effects in the male-female coevolution.
Collapse
Affiliation(s)
- Yacine Ben Chehida
- Laboratoire évolution, génomes et spéciation, CNRS UPR9034, 1, avenue de la terrasse, bâtiment 13, 91198 Gif-sur-Yvette Cedex, France - Université Paris-Sud, 91405 Orsay, France
| | - Béatrice Denis
- Laboratoire évolution, génomes et spéciation, CNRS UPR9034, 1, avenue de la terrasse, bâtiment 13, 91198 Gif-sur-Yvette Cedex, France - Université Paris-Sud, 91405 Orsay, France
| | - Gaëlle Claisse
- Laboratoire évolution, génomes et spéciation, CNRS UPR9034, 1, avenue de la terrasse, bâtiment 13, 91198 Gif-sur-Yvette Cedex, France - Université Paris-Sud, 91405 Orsay, France
| | - Dominique Joly
- Laboratoire évolution, génomes et spéciation, CNRS UPR9034, 1, avenue de la terrasse, bâtiment 13, 91198 Gif-sur-Yvette Cedex, France - Université Paris-Sud, 91405 Orsay, France
| |
Collapse
|
14
|
Klemme I, Bäumer J, Eccard JA, Ylönen H. Polyandrous females produce sons that are successful at post-copulatory competition. J Evol Biol 2014; 27:457-65. [DOI: 10.1111/jeb.12334] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/07/2014] [Accepted: 01/08/2014] [Indexed: 11/28/2022]
Affiliation(s)
- I. Klemme
- Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
| | - J. Bäumer
- Department of Animal Ecology; University of Potsdam; Potsdam Germany
| | - J. A. Eccard
- Department of Animal Ecology; University of Potsdam; Potsdam Germany
| | - H. Ylönen
- Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
| |
Collapse
|
15
|
Firman RC. Female fitness, sperm traits and patterns of paternity in an Australian polyandrous mouse. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1643-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
16
|
Firman RC, Simmons LW. Sperm competition risk generates phenotypic plasticity in ovum fertilizability. Proc Biol Sci 2013; 280:20132097. [PMID: 24132308 DOI: 10.1098/rspb.2013.2097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Theory predicts that sperm competition will generate sexual conflict that favours increased ovum defences against polyspermy. A recent study on house mice has shown that ovum resistance to fertilization coevolves in response to increased sperm fertilizing capacity. However, the capacity for the female gamete to adjust its fertilizability as a strategic response to sperm competition risk has never, to our knowledge, been studied. We sourced house mice (Mus domesticus) from natural populations that differ in the level of sperm competition and sperm fertilizing capacity, and manipulated the social experience of females during their sexual development to simulate conditions of either a future 'risk' or 'no risk' of sperm competition. Consistent with coevolutionary predictions, we found lower fertilization rates in ova produced by females from a high sperm competition population compared with ova from a low sperm competition population, indicating that these populations are divergent in the fertilizability of their ova. More importantly, females exposed to a 'risk' of sperm competition produced ova that had greater resistance to fertilization than ova produced by females reared in an environment with 'no risk'. Consequently, we show that variation in sperm competition risk during development generates phenotypic plasticity in ova fertilizability, which allows females to prepare for prevailing conditions during their reproductive life.
Collapse
Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, , Nedlands 6009, Australia
| | | |
Collapse
|
17
|
Simmons LW, Firman RC. EXPERIMENTAL EVIDENCE FOR THE EVOLUTION OF THE MAMMALIAN BACULUM BY SEXUAL SELECTION. Evolution 2013; 68:276-83. [DOI: 10.1111/evo.12229] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/30/2013] [Indexed: 02/05/2023]
Affiliation(s)
- Leigh W. Simmons
- Centre for Evolutionary Biology; School of Animal Biology (M092); The University of Western Australia; Crawley 6009 Australia
| | - Renée C. Firman
- Centre for Evolutionary Biology; School of Animal Biology (M092); The University of Western Australia; Crawley 6009 Australia
| |
Collapse
|
18
|
Garratt M, Bathgate R, de Graaf SP, Brooks RC. Copper-zinc superoxide dismutase deficiency impairs sperm motility and in vivo fertility. Reproduction 2013; 146:297-304. [PMID: 23847261 DOI: 10.1530/rep-13-0229] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Oxidative stress, overproduction of reactive oxygen species (ROS) in relation to defence mechanisms, is considered to be a major cause of male infertility. For protection against the deleterious effects of ROS, animals have a variety of enzymatic antioxidants that reduce these molecules to less reactive forms. The physiological role of these antioxidants in vivo has been explored extensively through genetic inhibition of gene expression; surprisingly, many of these animals remain fertile in spite of increased oxidative stress. Copper-zinc superoxide dismutase-deficient (Sod1(-/-)) male mice are one such example for which in vivo fertility has been repeatedly reported as normal, although examination of fertility has consisted of simply pairing animals of the same strain and checking for litters. This is a fairly low criterion by which to assess fertility. Herein, we show that Sod1-deficient males have zero fertilisation success in sperm competition trials that pit them against wild-type males of an otherwise identical genetic background and are almost completely infertile when mated singly with females of a different genotype. We also show that various aspects of sperm motility and function are impaired in Sod1-deficient mice. Testing the breeding capabilities of mice under more ecologically relevant conditions and with females of different genotypes may help reveal additional physiological causes of infertility.
Collapse
Affiliation(s)
- Michael Garratt
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales 2052, Australia.
| | | | | | | |
Collapse
|
19
|
Firman RC, Klemme I, Simmons LW. Strategic adjustments in sperm production within and between two island populations of house mice. Evolution 2013; 67:3061-70. [PMID: 24094355 DOI: 10.1111/evo.12164] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 04/18/2013] [Indexed: 11/28/2022]
Abstract
Sperm production is physiologically costly. Consequently, males are expected to be prudent in their sperm production, and tailor their expenditure according to prevailing social conditions. Differences in sperm production have been found across island populations of house mice that differ in the level of selection from sperm competition. Here, we determined the extent to which these differences represent phenotypic plasticity and/or population divergence in sperm production. We sourced individuals from two populations at the extreme levels of sperm competition, and raised them under common-garden conditions while manipulating the social experience of developing males. Males from the high-sperm competition population produced more sperm and better quality sperm than did males from the low-sperm competition population. In addition, males reared under a perceived "risk" of sperm competition produced greater numbers of sperm than males reared with "no risk." However, our analyses revealed that phenotypic plasticity in sperm production was greater for individuals from the high-sperm competition population. Our results are thus consistent with both population divergence and phenotypic plasticity in sperm production, and suggest that population level of sperm competition might affect the degree of adaptive plasticity in sperm production in response to sperm competition risk.
Collapse
Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Nedlands, 6009, Australia.
| | | | | |
Collapse
|