1
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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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2
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Hills A, Webster MM. Sampling biases and reproducibility: experimental design decisions affect behavioural responses in hermit crabs. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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3
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Dougherty LR. Meta-analysis shows the evidence for context-dependent mating behaviour is inconsistent or weak across animals. Ecol Lett 2021; 24:862-875. [PMID: 33471386 DOI: 10.1111/ele.13679] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 01/09/2023]
Abstract
Animals often need to invest significantly in mating behaviour in order to successfully mate. However, the expression of mating behaviour can be costly, especially in unfavourable environments, so animals are expected to adjust their behaviour in a context-dependent way to mitigate these costs. I systematically searched the literature for studies measuring animal mating behaviour (sexual signalling, response to sexual signals or the strength of mate choice) in more than one environment, and used a phylogenetically controlled meta-analysis to identify environmental factors influencing these behaviours. Across 222 studies, the strength of mate choice was significantly context-dependent, and most strongly influenced by population density, population sex ratio and predation risk. However, the average effect sizes were typically small. The amount of sexual signalling and the strength of response to sexual signals were not significantly related to the environment. Overall, this suggests that the evidence for context-dependent mating behaviour across animals is surprisingly weak.
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Affiliation(s)
- Liam R Dougherty
- Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7RB, UK
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4
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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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5
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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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6
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Cattelan S, Vidotto M, Devigili A, Pilastro A, Grapputo A. Differential gene regulation in selected lines for high and low sperm production in male guppies. Mol Reprod Dev 2020; 87:430-441. [PMID: 32100427 DOI: 10.1002/mrd.23332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/05/2020] [Indexed: 12/14/2022]
Abstract
In species where females mate with more than one male during the same reproductive event, males typically increase the number of sperm produced to boost their fertilization share. Sperm is not limitless, however, and theory predicts that their production will come at the cost of other fitness-related traits, such as body growth or immunocompetence, although these evolutionary trade-offs are notoriously difficult to highlight. To this end, we combined artificial selection for sperm production with a transcriptome analysis using Poecilia reticulata, a fish characterized by intense sperm competition in which the number of sperm transferred during mating is the most important predictor of fertilization success, yet sperm production is highly variable among males. We compared the brain and testes transcriptome in male guppies of lines artificially selected for high and low sperm production by identifying pivotal differentially expressed gene sets that may regulate spermatogenesis and immune function in this species. Despite the small differences in single genes' expression, gene set enrichment analysis showed coordinated gene expression differences associated with several pathways differentially regulated in the two selection lines. High sperm production males showed an upregulation of pathways related to immunosuppression and development of spermatozoa indicating a possible immunological cost of sperm production.
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7
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Gasparini C, Devigili A, Pilastro A. Sexual selection and ageing: interplay between pre- and post-copulatory traits senescence in the guppy. Proc Biol Sci 2020; 286:20182873. [PMID: 30963845 DOI: 10.1098/rspb.2018.2873] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Traits associated with mating and fertilization success are expected to senesce with age, but limited information is available on their relative rates of senescence. In polyandrous species, male reproductive fitness depends on both mating and fertilization success. Because successful mating is a prerequisite for post-copulatory sexual selection, ejaculate traits are expected to senesce faster than pre-copulatory traits, as pre-copulatory sexual selection is often deemed to be stronger than post-copulatory sexual selection. This pattern has generally been found in the few empirical studies conducted so far. We tested this prediction in the guppy ( Poecilia reticulata), a livebearing fish characterized by intense sperm competition, by comparing the expression of male sexual traits at two ages (four and nine months). Contrary to prediction, we found that post-copulatory traits senesced at a significantly slower rate than pre-copulatory traits. We also looked at whether early investment in those sexual traits affects longevity, and the interaction between sperm age (duration of sperm storage inside the male) and male age. Our results suggest that the relative senescence rate of pre- and post-copulatory sexual traits may vary among species with different mating systems and ecology.
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Affiliation(s)
- Clelia Gasparini
- 1 Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia , Crawley, Western Australia 6009 , Australia.,2 Department of Biology, University of Padova , 35131 Padova , Italy
| | - Alessandro Devigili
- 2 Department of Biology, University of Padova , 35131 Padova , Italy.,3 Department of Zoology, Stockholm University , Stockholm 106 91 , Sweden
| | - Andrea Pilastro
- 2 Department of Biology, University of Padova , 35131 Padova , Italy
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8
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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
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9
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Magris M, Chimetto G, Rizzi S, Pilastro A. Quick-change artists: male guppies pay no cost to repeatedly adjust their sexual strategies. Behav Ecol 2018. [DOI: 10.1093/beheco/ary087] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Martina Magris
- Department of Biology, University of Padova via U. Bassi, Padua, Italy
| | - Gianluca Chimetto
- Department of Biology, University of Padova via U. Bassi, Padua, Italy
| | - Sofia Rizzi
- Department of Biology, University of Padova via U. Bassi, Padua, Italy
| | - Andrea Pilastro
- Department of Biology, University of Padova via U. Bassi, Padua, Italy
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10
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11
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Scarponi V, Godin JGJ. Female assessment of male functional fertility during mate choice in a promiscuous fish. Ethology 2018. [DOI: 10.1111/eth.12723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Valentina Scarponi
- Department of Biology; Carleton University; Ottawa ON Canada
- Department of Life Sciences; University of Sussex; Brighton UK
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12
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Riesch R, Plath M, Bierbach D. Ecology and evolution along environmental gradients. Curr Zool 2018; 64:193-196. [PMID: 30402059 PMCID: PMC5905473 DOI: 10.1093/cz/zoy015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Rüdiger Riesch
- School of Biological Sciences, Centre for Ecology, Evolution and Behaviour, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Martin Plath
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - David Bierbach
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, D-12587, Germany
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13
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Lodi M, Staikou A, Janssen R, Koene JM. High level of sperm competition may increase transfer of accessory gland products carried by the love dart of land snails. Ecol Evol 2017; 7:11148-11156. [PMID: 29299289 PMCID: PMC5743536 DOI: 10.1002/ece3.3385] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 07/23/2017] [Accepted: 07/26/2017] [Indexed: 11/10/2022] Open
Abstract
Postcopulatory adaptations that increase reproductive success compared to rivals, like the transfer of accessory gland products that promote paternity, are common when sperm competition occurs among males. In land snails, the dart shooting behavior and its adaptive significance, in promoting individual fitness through enhanced paternity of the successful dart shooter, have been considered such an adaptation. The fitness result gained is mediated by the transfer of mucus components on the love dart capable of altering the physiology of the receiver's reproductive tract. In this context, dart shooting and mucus transfer could be considered as processes targeted by sexual selection. While the effect of dart mucus is beneficial for the dart user, so far it has remained unknown whether its transport is greater when snails experience a higher level of sperm competition. Here, we report results of a study on inter- and intraspecific variations of dart and mucus gland morphometry, considered to be traits reflecting the ability of snails to adjust the production and transfer of mucus under varying sperm competition scenarios. We investigated four populations with different densities from four dart-bearing species, Arianta arbustorum, Cepaea nemoralis, Cornu aspersum, and Helix lucorum. The results indicate that different adaptations of these traits occur among the studied species that all seem to achieve the same goal of transferring more mucus when sperm competition is higher. For example, the presence of longer and more branched mucous glands or an increase in dart surface most likely reflect increased mucus production and enhanced ability of mucus transport, respectively. Interestingly, the species for which the use of the dart is reported to be facultative, A. arbustorum, did not show any variation among the examined traits. To conclude, sexual selection in the form of sperm competition intensity seems to be an important selective force for these simultaneously hermaphroditic dart-bearing snails, driving differences in sexual traits.
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Affiliation(s)
- Monica Lodi
- Section of Animal Ecology Department of Ecological Science Faculty of Earth and Life Sciences VU University Amsterdam Amsterdam The Netherlands.,Naturalis Biodiversity Center Leiden The Netherlands
| | - Alexandra Staikou
- Department of Zoology School of Biology Aristotle University of Thessaloniki Thessaloniki Macedonia Greece
| | - Ruben Janssen
- Section of Conservation Biology Department of Environmental Sciences University of Basel Basel Switzerland
| | - Joris M Koene
- Section of Animal Ecology Department of Ecological Science Faculty of Earth and Life Sciences VU University Amsterdam Amsterdam The Netherlands.,Naturalis Biodiversity Center Leiden The Netherlands
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14
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Setoguchi S, Kudo A, Takanashi T, Ishikawa Y, Matsuo T. Social context-dependent modification of courtship behaviour in Drosophila prolongata. Proc Biol Sci 2016; 282:20151377. [PMID: 26538591 DOI: 10.1098/rspb.2015.1377] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform 'leg vibration', in which a male vibrates the female's body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to 'rubbing', which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration.
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Affiliation(s)
- Shiori Setoguchi
- Department of Agricultural and Environmental Biology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ayumi Kudo
- Department of Agricultural and Environmental Biology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takuma Takanashi
- Department of Forest Entomology, Forestry and Forest Products Research Institute, Matsuno-sato 1, Tsukuba, Ibaraki 305-8687, Japan
| | - Yukio Ishikawa
- Department of Agricultural and Environmental Biology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takashi Matsuo
- Department of Agricultural and Environmental Biology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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15
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Auge AC, Auld HL, Sherratt TN, Godin JGJ. Do Males Form Social Associations Based on Sexual Attractiveness in a Fission-Fusion Fish Society? PLoS One 2016; 11:e0151243. [PMID: 26986565 PMCID: PMC4795762 DOI: 10.1371/journal.pone.0151243] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 02/25/2016] [Indexed: 01/26/2023] Open
Abstract
Recent theory predicts that males should choose social environments that maximize their relative attractiveness to females by preferentially associating with less attractive rivals, so as to enhance their mating success. Using the Trinidadian guppy (Poecilia reticulata), a highly social species, we tested for non-random social associations among males in mixed-sex groups based on two phenotypic traits (body length and coloration) that predict relative sexual attractiveness to females and sexual (sperm) competitiveness. Based on a well-replicated laboratory dichotomous-choice test of social group preference, we could not reject the null hypothesis that focal males chose randomly between a mixed-sex group that comprised a female and a rival male that was less sexually attractive than themselves and another mixed-sex group containing a sexually more attractive male. The same conclusion was reached when females were absent from the two groups. As might be expected from these laboratory findings, free-ranging males in the field were not assorted by either body length or colour in mixed-sex shoals. The apparent lack of an evolved and expressed preference in wild male guppies from our study population to form social associations with other males based on their relative sexual attractiveness and competitiveness might be due to the fission-fusion dynamics of guppy shoals in nature. Such social dynamics likely places constraints on the formation of stable phenotype-based social associations among males. This possibility is supported by a simulation model which assumes group departure rules based on relative body size and coloration in males.
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Affiliation(s)
- Anne-Christine Auge
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Heather L. Auld
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | | | - Jean-Guy J. Godin
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
- * E-mail:
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16
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Sommer C, Olsén KH. Sex odour preference in guppy (Poecilia wingei) males is influenced by the social environment. BEHAVIOUR 2016. [DOI: 10.1163/1568539x-00003387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The social environment of animals, particularly in the early stages of life, can have great impact on species-specific and sex-specific behaviours. These changes can be irreversible and continue during the entire life. In the present study we asked the question whether the social environment of male Endler’s guppies,Poecilia wingei, housed in an all-male community could affect their preference response to female or male odour cues in a flow through Y-maze. After 30 days in an all-male group males were tested for their preference-avoidance responses to conspecific odours. The males were attracted to male-scented water but not to water scented by females. In simultaneous choice between male and female odours they demonstrated no significant preference. The males were attracted to male-scented water after they were kept for 48 h or 12 days with females. After the Y-maze tests the males’ were placed with two females and their courting behaviour were recorded. The males showed low frequencies of reproductive behaviours. In the all-male group the males had been courting each other. The results show that the social environment influence sexual odour preference and courting behaviour in guppy males.
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Affiliation(s)
- Christian Sommer
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, SE-141 89 Huddinge, Sweden
| | - K. Håkan Olsén
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, SE-141 89 Huddinge, Sweden
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17
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Scarponi V, Chowdhury D, Godin JGJ. Male Mating History Influences Female Mate Choice in the Trinidadian Guppy (Poecilia reticulata). Ethology 2015. [DOI: 10.1111/eth.12427] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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18
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Father absence and age at menarche : A test of four evolutionary models. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2015; 14:209-33. [PMID: 26190208 DOI: 10.1007/s12110-003-1004-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2002] [Revised: 11/15/2002] [Indexed: 10/23/2022]
Abstract
Life history data, attractiveness ratings of male photographs, and attitudes towards partnership and child-rearing of 321 women were used to test four evolutionary models (quantitative reproductive strategy, male short-age, polygyny indication, and maternal reproductive interests) which attempt to explain the influence of family composition on reproductive strategies. Links between early menarche and other markers of reproductive strategy were investigated. Childhood stress and absence of a father figure, whether genetically related or not, were found to have accelerated menarche whereas having younger siblings decelerated it. Early menarche was associated with attractiveness ratings, the number of partners desired for the immediate future, and the early onset of intimate relationships. It was not linked with sociosexual orientation, mate choice criteria, and investment in the subjects' own children, but these three markers were interrelated. The implications of the findings for the four evolutionary models are discussed.
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19
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Chunco AJ. Hybridization in a warmer world. Ecol Evol 2014; 4:2019-31. [PMID: 24963394 PMCID: PMC4063493 DOI: 10.1002/ece3.1052] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/01/2014] [Accepted: 03/11/2014] [Indexed: 01/09/2023] Open
Abstract
Climate change is profoundly affecting the evolutionary trajectory of individual species and ecological communities, in part through the creation of novel species assemblages. How climate change will influence competitive interactions has been an active area of research. Far less attention, however, has been given to altered reproductive interactions. Yet, reproductive interactions between formerly isolated species are inevitable as populations shift geographically and temporally as a result of climate change, potentially resulting in introgression, speciation, or even extinction. The susceptibility of hybridization rates to anthropogenic disturbance was first recognized in the 1930s. To date, work on anthropogenically mediated hybridization has focused primarily on either physical habitat disturbance or species invasion. Here, I review recent literature on hybridization to identify how ecological responses to climate change will increase the likelihood of hybridization via the dissolution of species barriers maintained by habitat, time, or behavior. Using this literature, I identify several cases where novel hybrid zones have recently formed, likely as a result of changing climate. Future research should focus on identifying areas and taxonomic groups where reproductive species interactions are most likely to be influenced by climate change. Furthermore, a better understanding of the evolutionary consequences of climate-mediated secondary contact is urgently needed. Paradoxically, hybridization is both a major conservation concern and an important source of novel genetic and phenotypic variation. Hybridization may therefore both contribute to increasing rates of extinction and stimulate the creation of novel phenotypes that will speed adaptation to novel climates. Predicting which result will occur following secondary contact will be an important contribution to conservation for many species.
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Affiliation(s)
- Amanda J Chunco
- Department of Environmental Studies, Elon University CB 2015, Elon, North Carolina 27244
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20
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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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21
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The effect of social environment on alternative mating tactics in male Endler's guppy, Poecilia wingei. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2013.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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22
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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.
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Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Nedlands, 6009, Australia.
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23
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Barbosa M, Ojanguren AF, Magurran AE. Courtship Display Persists Despite Early Social Deprivation. Ethology 2013. [DOI: 10.1111/eth.12087] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - Alfredo F. Ojanguren
- Scottish Oceans Institute; School of Biology; University of St Andrews; St Andrews; Fife; UK
| | - Anne E. Magurran
- Scottish Oceans Institute; School of Biology; University of St Andrews; St Andrews; Fife; UK
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24
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25
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Schrader M, Apodaca JJ, Macrae PSD, Travis J. Population density does not influence male gonadal investment in the Least Killifish, Heterandria formosa. Ecol Evol 2013; 2:2935-42. [PMID: 23301162 PMCID: PMC3538990 DOI: 10.1002/ece3.402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/06/2012] [Accepted: 09/17/2012] [Indexed: 11/06/2022] Open
Abstract
Comparative studies documenting a relationship between male gonadal investment and the degree of sperm competition (SC) have usually considered the association between these traits to be driven by qualitative differences in the mating system, such as whether spawning occurs in pairs or groups. However, ecological and demographic differences between conspecific populations may also generate variation in the importance of SC that can drive the evolution of male gonadal investment. In this study, we examined whether variation in population density, which is predicted to influence the level of SC in many animals, is correlated with male gonadal investment among populations of the least killifish, Heterandria formosa, a species with internal fertilization in which multiple mating is common. We complemented this field study by testing whether males respond plastically to experimentally increased levels of SC by increasing investment in testis. This experiment involved two treatments. In the first, we eliminated the potential for sperm competition (NSC) by housing a single male with a single female. In the second, we created a high risk of SC by housing five males with two females. In the field survey, we found significant differences among populations in density and relative testis mass. However, there was no evidence for a correlation between population density and relative testis mass. In our lab experiment, males did not adjust their gonadal investment in response to experiencing different levels of SC for 4 weeks. Our combined results indicate that gonadal investment in male H. formosa is not related to variation in population density.
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Affiliation(s)
- Matthew Schrader
- Department of Biological Science, Florida State University Tallahassee, Florida ; Department of Animal Biology, University of Illinois Urbana-Champaign Champaign, Illinois
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Guevara-Fiore P, Svensson PA, Endler JA. Sex as moderator of early life experience: interaction between rearing environment and sexual experience in male guppies. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.07.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Sex-specific plasticity in brain morphology depends on social environment of the guppy, Poecilia reticulata. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1403-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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de Jong K, Forsgren E, Sandvik H, Amundsen T. Measuring mating competition correctly: available evidence supports operational sex ratio theory. Behav Ecol 2012. [DOI: 10.1093/beheco/ars094] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AbstractCentral to sexual selection theory is the question of when individuals should compete for mates. Theory predicts that the sex ratio of ready-to-mate individuals (operational sex ratio; OSR) affects male and female mating competition. In accordance with this, the strength of mating competition, measured by agonistic behaviors and courtship displays, has been found to co-vary with the OSR in field populations of several species. However, laboratory experiments have often produced results that seemingly contradict OSR theory, especially for courtship behavior. We argue that this may be because experiments typically measure frequencies of competitive behaviors. Frequencies of courtship and agonistic behavior are not only affected by the level of mating competition, but also by the number of potential mates or competitors encountered. In contrast, the propensity to behave competitively at a given encounter represents a behavioral response, and thus directly reflects mating competition. We show in 2 simple models that 1) courtship frequency can be expected to respond differently from courtship propensity to changes in OSR and 2) an increase in frequency of agonistic behaviors could occur even if the propensity is not affected by the OSR. In a meta-analysis of studies on courtship competition, we show that frequency measures produced largely opposite results to propensity measures, as predicted by our model. Moreover, courtship propensity increased when the OSR became more biased toward competitors. This presents strong evidence that the OSR affects competition, in the form of courtship, as predicted by OSR theory.
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Affiliation(s)
- Karen de Jong
- Department of Biology, Norwegian University of Science and Technology (NTNU) 7491 Trondheim, Norwayand
| | - Elisabet Forsgren
- The Norwegian Institute for Nature Research (NINA) 7485 Trondheim, Norway
| | - Hanno Sandvik
- Department of Biology, Norwegian University of Science and Technology (NTNU) 7491 Trondheim, Norwayand
| | - Trond Amundsen
- Department of Biology, Norwegian University of Science and Technology (NTNU) 7491 Trondheim, Norwayand
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Shenoy K. Environmentally realistic exposure to the herbicide atrazine alters some sexually selected traits in male guppies. PLoS One 2012; 7:e30611. [PMID: 22312428 PMCID: PMC3270011 DOI: 10.1371/journal.pone.0030611] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 12/25/2011] [Indexed: 11/18/2022] Open
Abstract
Male mating signals, including ornaments and courtship displays, and other sexually selected traits, like male-male aggression, are largely controlled by sex hormones. Environmental pollutants, notably endocrine disrupting compounds, can interfere with the proper functioning of hormones, thereby impacting the expression of hormonally regulated traits. Atrazine, one of the most widely used herbicides, can alter sex hormone levels in exposed animals. I tested the effects of environmentally relevant atrazine exposures on mating signals and behaviors in male guppies, a sexually dimorphic freshwater fish. Prolonged atrazine exposure reduced the expression of two honest signals: the area of orange spots (ornaments) and the number of courtship displays performed. Atrazine exposure also reduced aggression towards competing males in the context of mate competition. In the wild, exposure levels vary among individuals because of differential distribution of the pollutants across habitats; hence, differently impacted males often compete for the same mates. Disrupted mating signals can reduce reproductive success as females avoid mating with perceptibly suboptimal males. Less aggressive males are at a competitive disadvantage and lose access to females. This study highlights the effects of atrazine on ecologically relevant mating signals and behaviors in exposed wildlife. Altered reproductive traits have important implications for population dynamics, evolutionary patterns, and conservation of wildlife species.
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Affiliation(s)
- Kausalya Shenoy
- Department of Biology, University of Kentucky, Lexington, Kentucky, United States of America.
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31
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McKellar AE, Hendry AP. Environmental factors influencing adult sex ratio in Poecilia reticulata: laboratory experiments. JOURNAL OF FISH BIOLOGY 2011; 79:937-953. [PMID: 21967582 DOI: 10.1111/j.1095-8649.2011.03065.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The potential causes of adult sex ratio variation in guppies Poecilia reticulata were tested in laboratory experiments that evaluated the mortality rates of male and female P. reticulata exposed to potential predators (Hart's rivulus Rivulus hartii and freshwater prawns Macrobrachium crenulatum) and to different resource levels. Poecilia reticulata mortality increased in the presence of R. hartii and M. crenulatum, and low resource levels had an effect on mortality only in the presence of M. crenulatum. Rivulus hartii preyed more often on male than on female P. reticulata, and this sex-biased predation was not simply the result of males being smaller than females. In contrast, no sex-biased mortality was attributable to M. crenulatum or low resource levels.
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Affiliation(s)
- A E McKellar
- Redpath Museum and Department of Biology, McGill University, 859 Sherbrooke Street West, Montréal, QC, H3A 2K6 Canada.
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Karlsson K, Eroukhmanoff F, Svensson EI. Phenotypic plasticity in response to the social environment: effects of density and sex ratio on mating behaviour following ecotype divergence. PLoS One 2010; 5. [PMID: 20862332 PMCID: PMC2940798 DOI: 10.1371/journal.pone.0012755] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 08/04/2010] [Indexed: 11/19/2022] Open
Abstract
The ability to express phenotypically plastic responses to environmental cues might be adaptive in changing environments. We studied phenotypic plasticity in mating behaviour as a response to population density and adult sex ratio in a freshwater isopod (Asellus aquaticus). A. aquaticus has recently diverged into two distinct ecotypes, inhabiting different lake habitats (reed Phragmites australis and stonewort Chara tomentosa, respectively). In field surveys, we found that these habitats differ markedly in isopod population densities and adult sex ratios. These spatially and temporally demographic differences are likely to affect mating behaviour. We performed behavioural experiments using animals from both the ancestral ecotype (“reed” isopods) and from the novel ecotype (“stonewort” isopods) population. We found that neither ecotype adjusted their behaviour in response to population density. However, the reed ecotype had a higher intrinsic mating propensity across densities. In contrast to the effects of density, we found ecotype differences in plasticity in response to sex ratio. The stonewort ecotype show pronounced phenotypic plasticity in mating propensity to adult sex ratio, whereas the reed ecotype showed a more canalised behaviour with respect to this demographic factor. We suggest that the lower overall mating propensity and the phenotypic plasticity in response to sex ratio have evolved in the novel stonewort ecotype following invasion of the novel habitat. Plasticity in mating behaviour may in turn have effects on the direction and intensity of sexual selection in the stonewort habitat, which may fuel further ecotype divergence.
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Affiliation(s)
- Kristina Karlsson
- Section for Animal Ecology, Department of Biology, Lund University, Lund, Sweden.
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33
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Zajitschek SRK, Brooks RC. Inbreeding depression in male traits and preference for outbred males in Poecilia reticulata. Behav Ecol 2010. [DOI: 10.1093/beheco/arq077] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Valero A, Magurran AE, Garcia CM. Guppy males distinguish between familiar and unfamiliar females of a distantly related species. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.05.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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Ramm SA, Stockley P. Adaptive plasticity of mammalian sperm production in response to social experience. Proc Biol Sci 2009; 276:745-51. [PMID: 18986975 DOI: 10.1098/rspb.2008.1296] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sperm competition theory predicts that males should invest prudently in ejaculates according to levels of female promiscuity. Males may therefore be sensitive to cues in their social environment associated with sexual competition, and tailor investment in sperm production accordingly. We tested this idea experimentally for the first time, to our knowledge, in a mammal by comparing reproductive traits of male house mice (Mus musculus domesticus) that had experienced contrasting encounter regimes with potential sexual competitors. We found that daily sperm production and numbers of sperm in the caput epididymis were significantly higher in subjects that had experienced a high encounter rate of social cues from three other males compared to those that had experienced a low encounter rate of social cues from just one other male. Epididymal sperm counts were negatively correlated with the frequency of scent-marking behaviour across all males in our study, suggesting that investment in ejaculate production may be traded off against traits that function in gaining copulations, although there was no difference in overall levels of scent marking between treatment groups. We conclude that social experience-mediated phenotypic plasticity in mammalian spermatogenesis is likely to be adaptive under sperm competition, enabling males to balance the energetic costs and paternity-enhancing benefits of ejaculate production, and is a potentially widespread explanation for intraspecific variation in ejaculate expenditure.
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Affiliation(s)
- Steven A Ramm
- Mammalian Behaviour and Evolution Group, University of Liverpool, Leahurst Campus, Neston CH64 7TE, UK.
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36
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Evans JP. No evidence for sperm priming responses under varying sperm competition risk or intensity in guppies. Naturwissenschaften 2009; 96:771-9. [DOI: 10.1007/s00114-009-0529-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 03/10/2009] [Accepted: 03/10/2009] [Indexed: 10/21/2022]
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37
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Environmental factors influencing adult sex ratio in Trinidadian guppies. Oecologia 2009; 159:735-45. [DOI: 10.1007/s00442-008-1257-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 12/03/2008] [Indexed: 11/25/2022]
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38
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Valero A, Macías Garcia C, Magurran AE. Heterospecific harassment of native endangered fishes by invasive guppies in Mexico. Biol Lett 2008; 4:149-52. [PMID: 18211863 DOI: 10.1098/rsbl.2007.0604] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Persistent courtship by male Trinidadian guppies (Poecilia reticulata) is costly for conspecific females. Since male guppies are known to attempt matings with other poeciliid females, we asked whether persistent courtship is also directed towards morphologically similar but phylogenetically distant females encountered following invasion. Skiffia bilineata is one of several endangered viviparous goodeids from Central México, whose remaining habitats are increasingly shared with invasive guppies. Experiments in which guppy sex ratios were manipulated to vary the proportion of heterospecific to conspecific females showed that male guppies courted and attempted forced copulations with S. bilineata females even when females of their own species were in excess. This behaviour places an additional, and previously unrecognized, burden on a group of endemic Mexican fishes already in risk of extinction.
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Affiliation(s)
- Alejandra Valero
- Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife KY16 8LB, UK
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Head ML, Lindholm AK, Brooks R. OPERATIONAL SEX RATIO AND DENSITY DO NOT AFFECT DIRECTIONAL SELECTION ON MALE SEXUAL ORNAMENTS AND BEHAVIOR. Evolution 2007; 62:135-44. [DOI: 10.1111/j.1558-5646.2007.00277.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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40
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Pilastro A, Mandelli M, Gasparini C, Dadda M, Bisazza A. Copulation duration, insemination efficiency and male attractiveness in guppies. Anim Behav 2007. [DOI: 10.1016/j.anbehav.2006.09.016] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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Environmental and genetic influences on mating strategies along a replicated food availability gradient in guppies (Poecilia reticulata). Behav Ecol Sociobiol 2006. [DOI: 10.1007/s00265-006-0299-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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42
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Viken A, Fleming IA, Rosenqvist G. Premating Avoidance of Inbreeding Absent in Female Guppies (Poecilia reticulata). Ethology 2006. [DOI: 10.1111/j.1439-0310.2006.01225.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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43
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Jensen MP, Abreu-Grobois FA, Frydenberg J, Loeschcke V. Microsatellites provide insight into contrasting mating patterns in arribada vs. non-arribada olive ridley sea turtle rookeries. Mol Ecol 2006; 15:2567-75. [PMID: 16842427 DOI: 10.1111/j.1365-294x.2006.02951.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular studies of sea turtles have shown that the frequency of multiple paternity (MP) varies between species, and between rookeries of the same species. This study uses nuclear microsatellite markers to compare the incidence of MP in two neighbouring olive ridley rookeries on the Pacific coast of Costa Rica, with contrasting nesting behaviours -- the 'arribada' population nesting at Ostional and the solitary nesters of Playa Hermosa. Using two highly polymorphic microsatellite markers, we tested 13 nests from each location and found a significant difference (P < 0.001) between the level of MP of the arribada rookery (92%- the highest found for marine turtles) and that of the solitary nesting rookery (30%). Additional analyses based on six microsatellite loci revealed no genetic differentiation between nesting females from the two locations, or between nesting females and attendant males from the Ostional breeding area. Sixty-nine per cent of the nests with MP were fathered by a minimum of three different males, and three nests showed evidence of at least four fathers. The results suggest that the differences observed in levels of MP between arribada and solitary rookeries are due to an effect of abundance of individuals on the mating system. This is supported by a regression analysis combining other paternity studies on sea turtles which shows that levels of MP increase with increasing abundance of nesting females.
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Affiliation(s)
- M P Jensen
- Department of Biological Sciences, Ecology and Genetics, University of Aarhus, Ny Munkegade, Build. 540, DK-8000 Aarhus C, Denmark.
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Kokko H, Rankin DJ. Lonely hearts or sex in the city? Density-dependent effects in mating systems. Philos Trans R Soc Lond B Biol Sci 2006; 361:319-34. [PMID: 16612890 PMCID: PMC1569612 DOI: 10.1098/rstb.2005.1784] [Citation(s) in RCA: 436] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Two very basic ideas in sexual selection are heavily influenced by numbers of potential mates: the evolution of anisogamy, leading to sex role differentiation, and the frequency dependence of reproductive success that tends to equalize primary sex ratios. However, being explicit about the numbers of potential mates is not typical to most evolutionary theory of sexual selection. Here, we argue that this may prevent us from finding the appropriate ecological equilibria that determine the evolutionary endpoints of selection. We review both theoretical and empirical advances on how population density may influence aspects of mating systems such as intrasexual competition, female choice or resistance, and parental care. Density can have strong effects on selective pressures, whether or not there is phenotypic plasticity in individual strategies with respect to density. Mating skew may either increase or decrease with density, which may be aided or counteracted by changes in female behaviour. Switchpoints between alternative mating strategies can be density dependent, and mate encounter rates may influence mate choice (including mutual mate choice), multiple mating, female resistance to male mating attempts, mate searching, mate guarding, parental care, and the probability of divorce. Considering density-dependent selection may be essential for understanding how populations can persist at all despite sexual conflict, but simple models seem to fail to predict the diversity of observed responses in nature. This highlights the importance of considering the interaction between mating systems and population dynamics, and we strongly encourage further work in this area.
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Affiliation(s)
- Hanna Kokko
- Laboratory of Ecological and Evolutionary Dynamics, Department of Biological and Environmental Science, University of Helsinki, PO Box 65 (Vükinkaari 1), 00014 Helsinki, Finland.
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45
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Rubolini D, Galeotti P, Ferrari G, Spairani M, Bernini F, Fasola M. Sperm allocation in relation to male traits, female size, and copulation behaviour in freshwater crayfish species. Behav Ecol Sociobiol 2006. [DOI: 10.1007/s00265-005-0158-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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46
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Denoël M, Hector MP, Poncin P. COURTSHIP BEHAVIOR IN THE ALPINE NEWT TRITURUS ALPESTRIS AT TWO DIFFERENT DENSITIES OF MALES. HERPETOLOGICA 2005. [DOI: 10.1655/04-55.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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47
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Candolin U, Salesto T. Effects of increased vegetation cover on nesting behavior of sticklebacks (Gasterosteus aculeatus). Behav Ecol Sociobiol 2005. [DOI: 10.1007/s00265-005-0098-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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48
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Hughes KA, Rodd FH, Reznick DN. Genetic and environmental effects on secondary sex traits in guppies (Poecilia reticulata). J Evol Biol 2005; 18:35-45. [PMID: 15669959 DOI: 10.1111/j.1420-9101.2004.00806.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Male guppies (Poecilia reticulata) exhibit extreme phenotypic and genetic variability for several traits that are important to male fitness, and several lines of evidence suggest that resource level affects phenotypic expression of these traits in nature. We tested the hypothesis that genetic variation for male secondary sex traits could be maintained by genotype-specific effects of variable resource levels (genotype-environment interaction). To do this, we measured genetic variation and covariation under two environmental conditions--relatively low and relatively high food availability. We found high levels of genetic variation for most traits, but we only found a significant G x E interaction across food levels for one trait (body size) for one population. The across-environment correlations for size were large and positive, indicating that the reaction norms for size did not cross. We also found that male colour pattern elements had nearly an order of magnitude more genetic variation than did male size. Heritability estimates indicated that Y-linked genes are responsible for some of the genetic variation in male size and colour traits. We discuss implications of these results for theories of the maintenance of genetic variation in male secondary sexual traits in guppies.
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Affiliation(s)
- K A Hughes
- School of Integrative Biology, University of Illinois, Urbana, IL 61801, USA.
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Abstract
As females of many species mate with more than one male, ejaculates often face competition from the sperm of other males. In recent years, numerous papers have been published on theoretical predictions of evolutionary, behavioural and physiological responses to variation in the strength of sperm competition (SC). These theoretical predictions have also been extensively tested. However, although predictions from SC theory are relatively straightforward, extra caution has to be paid in the design of experiments testing them. One difficulty is for example to disentangle immediate and mean SC risk and intensity. Without carefully designed experiments, it is also very easy to simultaneously increase SC risk and the probability of intense SC--a situation for which we currently have no clear predictions, as the theoretical models to date only assume variation in either SC risk or intensity. In this paper, we discuss these and some other pitfalls related to manipulations of SC risk and intensity and suggest how to avoid them.
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Affiliation(s)
- L Engqvist
- Institut für Evolutionsbiologie und Okologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.
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50
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