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Lackey ACR, Boughman JW. Female discrimination against heterospecific mates does not depend on mating habitat. Behav Ecol 2014. [DOI: 10.1093/beheco/aru111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Kim D, Waller J, Aspbury AS, Gabor CR. Mating Preferences of the Gynogenetic Amazon Molly Differ Between Populations Sympatric with Different Host Species. Ethology 2014. [DOI: 10.1111/eth.12278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Diana Kim
- Department of Biology; Texas State University; San Marcos TX USA
| | - John Waller
- Department of Biology, Experimental Evolution, Ecology & Behaviour; Lund University; Lund Sweden
| | | | - Caitlin R. Gabor
- Department of Biology; Texas State University; San Marcos TX USA
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Räsänen K, Hendry AP. Asymmetric reproductive barriers and mosaic reproductive isolation: insights from Misty lake-stream stickleback. Ecol Evol 2014; 4:1166-75. [PMID: 24772291 PMCID: PMC3997330 DOI: 10.1002/ece3.1012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/30/2014] [Accepted: 01/31/2014] [Indexed: 01/25/2023] Open
Abstract
Ecological speciation seems to occur readily but is clearly not ubiquitous - and the relative contributions of different reproductive barriers remain unclear in most systems. We here investigate the potential importance of selection against migrants in lake/stream stickleback (Gasterosteus aculeatus) from the Misty Lake system, Canada. This system is of particular interest because one population contrast (Lake vs. Outlet stream) shows very low genetic and morphological divergence, whereas another population contrast (Lake vs. Inlet stream) shows dramatic genetic and morphological divergence apparently without strong and symmetric reproductive barriers. To test whether selection against migrants might solve this "conundrum of missing reproductive isolation", we performed a fully factorial reciprocal transplant experiment using 225 individually marked stickleback collected from the wild. Relative fitness of the different ecotypes (Lake, Inlet, and Outlet) was assessed based on survival and mass change in experimental enclosures. We found that Inlet fish performed poorly in the lake (selection against migrants in that direction), whereas Lake fish outperformed Inlet fish in all environments (no selection against migrants in the opposite direction). As predicted from their phenotypic and genetic similarity, Outlet and Lake fish performed similarly in all environments. These results suggest that selection against migrants is asymmetric and, together with previous work, indicates that multiple reproductive barriers contribute to reproductive isolation. Similar mosaic patterns of reproductive isolation are likely in other natural systems.
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Affiliation(s)
- Katja Räsänen
- Redpath Museum and Department of Biology, McGill University 859 Sherbrooke St. W, Montréal, QC, H3A 2K6, Canada
| | - Andrew P Hendry
- Redpath Museum and Department of Biology, McGill University 859 Sherbrooke St. W, Montréal, QC, H3A 2K6, Canada
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55
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Chaffee DW, Griffin H, Gilman RT. Sexual imprinting: what strategies should we expect to see in nature? Evolution 2013; 67:3588-99. [PMID: 24299410 DOI: 10.1111/evo.12226] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 07/30/2013] [Indexed: 12/01/2022]
Abstract
Sexual imprinting occurs when juveniles learn mate preferences by observing the phenotypes of other members of their populations, and it is ubiquitous in nature. Imprinting strategies, that is which individuals and phenotypes are observed and how strong preferences become, vary among species. Imprinting can affect trait evolution and the probability of speciation, and different imprinting strategies are expected to have different effects. However, little is known about how and why different imprinting strategies evolve, or which strategies we should expect to see in nature. We used a mathematical model to study how the evolution of sexual imprinting depends on (1) imprinting costs and (2) the sex-specific fitness effects of the phenotype on which individuals imprint. We found that even small fixed costs prevent the evolution of sexual imprinting, but small relative costs do not. When imprinting does evolve, we identified the conditions under which females should evolve to imprint on their fathers, their mothers, or on other members of their populations. Our results provide testable hypotheses for empirical work and help to explain the conditions under which sexual imprinting might evolve to promote speciation.
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Affiliation(s)
- Dalton W Chaffee
- National Institute for Mathematical and Biological Synthesis, 1122 Volunteer Boulevard, Suite 106, University of Tennessee, Knoxville, Tennessee, 37996-3410
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56
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Zinck L, Lima SQ. Mate choice in Mus musculus is relative and dependent on the estrous state. PLoS One 2013; 8:e66064. [PMID: 23762466 PMCID: PMC3677927 DOI: 10.1371/journal.pone.0066064] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/03/2013] [Indexed: 11/20/2022] Open
Abstract
Mate choice is a critical behavioral decision process with profound impact on evolution. However, the mechanistic basis of mate choice is poorly understood. In this study we focused on assortative mate choice, which is known to contribute to the reproductive isolation of the two European subspecies of house mouse, Mus musculus musculus and Mus musculus domesticus. To understand the decision process, we developed both full mating and limited-contact paradigms and tested musculus females' preference for musculus versus domesticus males, mimicking the natural musculus/domesticus contact zone. As hypothesized, when allowed to mate we found that sexually receptive musculus females exhibited a robust preference to mate with musculus males. In contrast, when non-receptive, females did not exhibit a preference and rather alternated between males in response to male mount attempts. Moreover in a no-choice condition, females mated readily with males from both subspecies. Finally, when no physical contact was allowed, and therefore male's behavior could not influence female's behavior, female's preference for its own subspecies was maintained independently of the estrous state. Together, our results suggest that the assortative preference is relative and based on a comparison of the options available rather than on an absolute preference. The results of the limited-contact experiments highlight the interplay between female's internal state and the nature of the interaction with prospective mates in the full mating conditions. With these experiments we believe we established an assortative mate preference assay that is appropriate for the investigation of its underlying substrates.
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Affiliation(s)
- Léa Zinck
- Champalimaud Neuroscience Program, Champalimaud Centre for the Unknown, Lisbon, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Susana Q. Lima
- Champalimaud Neuroscience Program, Champalimaud Centre for the Unknown, Lisbon, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
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58
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Head ML, Kozak GM, Boughman JW. Female mate preferences for male body size and shape promote sexual isolation in threespine sticklebacks. Ecol Evol 2013; 3:2183-96. [PMID: 23919161 PMCID: PMC3728956 DOI: 10.1002/ece3.631] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 05/09/2013] [Accepted: 05/10/2013] [Indexed: 12/22/2022] Open
Abstract
Female mate preferences for ecologically relevant traits may enhance natural selection, leading to rapid divergence. They may also forge a link between mate choice within species and sexual isolation between species. Here, we examine female mate preference for two ecologically important traits: body size and body shape. We measured female preferences within and between species of benthic, limnetic, and anadromous threespine sticklebacks (Gasterosteus aculeatus species complex). We found that mate preferences differed between species and between contexts (i.e., within vs. between species). Within species, anadromous females preferred males that were deep bodied for their size, benthic females preferred larger males (as measured by centroid size), and limnetic females preferred males that were more limnetic shaped. In heterospecific mating trials between benthics and limnetics, limnetic females continued to prefer males that were more limnetic like in shape when presented with benthic males. Benthic females showed no preferences for size when presented with limnetic males. These results show that females use ecologically relevant traits to select mates in all three species and that female preference has diverged between species. These results suggest that sexual selection may act in concert with natural selection on stickleback size and shape. Further, our results suggest that female preferences may track adaptation to local environments and contribute to sexual isolation between benthic and limnetic sticklebacks.
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Affiliation(s)
- Megan L Head
- Centre for Ecology and Conservation, School of Biosciences, University of Exeter Cornwall Campus, Penryn, TR10 9EZ, UK
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59
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Phenotypic divergence among west European populations of Reed Bunting Emberiza schoeniclus: the effects of migratory and foraging behaviours. PLoS One 2013; 8:e63248. [PMID: 23667594 PMCID: PMC3646775 DOI: 10.1371/journal.pone.0063248] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 04/02/2013] [Indexed: 11/19/2022] Open
Abstract
Divergent selection and local adaptation are responsible for many phenotypic differences between populations, potentially leading to speciation through the evolution of reproductive barriers. Here we evaluated the morphometric divergence among west European populations of Reed Bunting in order to determine the extent of local adaptation relative to two important selection pressures often associated with speciation in birds: migration and diet. We show that, as expected by theory, migratory E. s. schoeniclus had longer and more pointed wings and a slightly smaller body mass than the resident subspecies, with the exception of E. s. lusitanica, which despite having rounder wings was the smallest of all subspecies. Tail length, however, did not vary according to the expectation (shorter tails in migrants) probably because it is strongly correlated with wing length and might take longer to evolve. E. s. witherbyi, which feed on insects hiding inside reed stems during the winter, had a very thick, stubby bill. In contrast, northern populations, which feed on seeds, had thinner bills. Despite being much smaller, the southern E. s. lusitanica had a significantly thicker, longer bill than migratory E. s. schoeniclus, whereas birds from the UK population had significantly shorter, thinner bills. Geometric morphometric analyses revealed that the southern subspecies have a more convex culmen than E. s. schoeniclus, and E. s. lusitanica differs from the nominate subspecies in bill shape to a greater extent than in linear bill measurements, especially in males. Birds with a more convex culmen are thought to exert a greater strength at the bill tip, which is in agreement with their feeding technique. Overall, the three subspecies occurring in Western Europe differ in a variety of traits following the patterns predicted from their migratory and foraging behaviours, strongly suggesting that these birds have became locally adapted through natural selection.
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60
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Servedio MR, Dukas R. Effects on population divergence of within-generational learning about prospective mates. Evolution 2013; 67:2363-75. [PMID: 23888857 DOI: 10.1111/evo.12127] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 03/18/2013] [Indexed: 11/28/2022]
Abstract
Although learned mate preferences are suspected to have important effects during speciation, theoretical models have largely neglected the effects on speciation and population divergence of within-generational learning, that is, learning based upon prior experience with potential mates. Here, we use population genetic models to address this deficit. Focusing on the situation of secondary contact between populations that still hybridize, we consider models of learning by females and by males under polygyny. We assess the effects of learning to prefer conspecifics from previous conspecific encounters, learning to avoid heterospecifics from previous heterospecific encounters, and learning to prefer familiar types. We examine the amount of population divergence that results from learning in these models. We also assess the effect of learning on the spread of an allele that strengthens assortative mating in both models. We find that learning can have counterintuitive, but logical and understandable effects that differ with the version of the model assessed. In general, population divergence is expected to increase most consistently when females learn to strengthen their preferences for conspecifics from previous encounters with conspecifics. Our results also suggest that within-generational learning will generally inhibit the spread of alleles strengthening assortative mating.
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Affiliation(s)
- Maria R Servedio
- Department of Biology, University of North Carolina, Coker Hall, CB# 3280, Chapel Hill, North Carolina 27599, USA.
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Seymour M, Räsänen K, Holderegger R, Kristjánsson BK. Connectivity in a pond system influences migration and genetic structure in threespine stickleback. Ecol Evol 2013; 3:492-502. [PMID: 23531709 PMCID: PMC3605840 DOI: 10.1002/ece3.476] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 12/11/2012] [Accepted: 12/11/2012] [Indexed: 11/08/2022] Open
Abstract
Neutral genetic structure of natural populations is primarily influenced by migration (the movement of individuals and, subsequently, their genes) and drift (the statistical chance of losing genetic diversity over time). Migration between populations is influenced by several factors, including individual behavior, physical barriers, and environmental heterogeneity among populations. However, drift is expected to be stronger in populations with low immigration rate and small effective population size. With the technological advancement in geological information systems and spatial analysis tools, landscape genetics now allows the development of realistic migration models and increased insight to important processes influencing diversity of natural populations. In this study, we investigated the relationship between landscape connectivity and genetic distance of threespine stickleback (Gasterosteus aculeatus) inhabiting a pond complex in Belgjarskógur, Northeast Iceland. We used two landscape genetic approaches (i.e., least-cost-path and isolation-by-resistance) and asked whether gene flow, as measured by genetic distance, was more strongly associated with Euclidean distance (isolation-by-distance) or with landscape connectivity provided by areas prone to flooding (as indicated by Carex sp. cover)? We found substantial genetic structure across the study area, with pairwise genetic distances among populations (DPS) ranging from 0.118 to 0.488. Genetic distances among populations were more strongly correlated with least-cost-path and isolation-by-resistance than with Euclidean distance, whereas the relative contribution of isolation-by-resistance and Euclidian distance could not be disentangled. These results indicate that migration among stickleback populations occurs via periodically flooded areas. Overall, this study highlights the importance of transient landscape elements influencing migration and genetic structure of populations at small spatial scales.
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Affiliation(s)
- Mathew Seymour
- Department of Aquatic Ecology and Institute of Integrative Biology, EAWAGETH Zurich, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland
- Department of Aquaculture and Fish Biology, Hólar University CollegeHáeyri 1, 550 Skagafjörður, Iceland
| | - Katja Räsänen
- Department of Aquatic Ecology and Institute of Integrative Biology, EAWAGETH Zurich, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland
| | - Rolf Holderegger
- Biodiversity and Conservation Biology, WSL Swiss Federal Research InstituteCH-8903 Birmensdorf, Switzerland
| | - Bjarni K Kristjánsson
- Department of Aquaculture and Fish Biology, Hólar University CollegeHáeyri 1, 550 Skagafjörður, Iceland
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Conte GL, Schluter D. Experimental confirmation that body size determines mate preference via phenotype matching in a stickleback species pair. Evolution 2013; 67:1477-84. [PMID: 23617922 DOI: 10.1111/evo.12041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/05/2012] [Indexed: 11/29/2022]
Abstract
Mate choice by phenotype matching, whereby individuals prefer a mate whose phenotype is similar to their own, should facilitate speciation with gene flow. This is because the genes that control mate signal (the phenotype being matched) also determine the preferred mate signal ("mate preference"). Speciation is made even easier if phenotype matching is based on a trait under divergent natural selection. In this case, assortative mating should readily evolve as a byproduct of divergent selection on the trait. Previous observational studies of assortative mating between sympatric, hybridizing threespine stickleback species (Gasterosteus aculeatus complex) suggested that phenotype matching might occur by body size, a trait under divergent natural selection. To test this, we used experimental manipulation of body size to rule out the effects of confounding variables. We found that size-manipulated benthic and limnetic stickleback females prefer mates whose body size more closely matches their own. It is thus likely that assortative mating by phenotype matching has facilitated the origin and persistence of benthic and limnetic threespine sticklebacks in the face of gene flow.
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Affiliation(s)
- Gina L Conte
- Biodiversity Research Centre and Zoology Department, University of British Columbia, Vancouver, British, Columbia, Canada, V6T 1Z4.
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66
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Ward JL, Blum MJ. Exposure to an environmental estrogen breaks down sexual isolation between native and invasive species. Evol Appl 2012; 5:901-12. [PMID: 23346234 PMCID: PMC3552407 DOI: 10.1111/j.1752-4571.2012.00283.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 05/15/2012] [Indexed: 11/30/2022] Open
Abstract
Environmental change can increase the likelihood of interspecific hybridization by altering properties of mate recognition and discrimination between sympatric congeners. We examined how exposure to an environmentally widespread endocrine-disrupting chemical (EDC), bisphenol A (BPA), affected visual communication signals and behavioral isolation between an introduced freshwater fish and a native congener (genus: Cyprinella). Exposure to BPA induced changes in the expression of male secondary traits as well as male and female mate choice, leading to an overall reduction in prezygotic isolation between congeners. Changes in female mate discrimination were not tightly linked to changes in male phenotypic traits, suggesting that EDC exposure may alter female choice thresholds independently of the effects of exposure on males. These findings indicate that environmental exposure to EDCs can lead to population declines via the erosion of species boundaries and by promoting the establishment and spread of non-native species via hybridization.
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Affiliation(s)
- Jessica L Ward
- Department of Ecology and Evolutionary Biology, Tulane UniversityNew Orleans, LA, USA
- Department of Fisheries, Wildlife and Conservation Biology and Department of Ecology, Evolution and Behavior, University of MinnesotaSaint Paul, MN, USA
| | - Michael J Blum
- Department of Ecology and Evolutionary Biology, Tulane UniversityNew Orleans, LA, USA
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67
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Kozak GM, Head ML, Lackey ACR, Boughman JW. Sequential mate choice and sexual isolation in threespine stickleback species. J Evol Biol 2012. [DOI: 10.1111/jeb.12034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- G. M. Kozak
- Department of Zoology; University of Wisconsin; Madison WI USA
| | - M. L. Head
- Centre for Ecology and Conservation; School of Biosciences; University of Exeter; Penryn UK
| | - A. C. R. Lackey
- Department of Zoology, BEACON, Ecology, Evolutionary Biology & Behavior Program; Michigan State University; East Lansing MI USA
| | - J. W. Boughman
- Department of Zoology, BEACON, Ecology, Evolutionary Biology & Behavior Program; Michigan State University; East Lansing MI USA
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Verzijden MN, ten Cate C, Servedio MR, Kozak GM, Boughman JW, Svensson EI. The impact of learning on sexual selection and speciation. Trends Ecol Evol 2012; 27:511-9. [DOI: 10.1016/j.tree.2012.05.007] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 05/11/2012] [Accepted: 05/17/2012] [Indexed: 10/28/2022]
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McKinnon JS, Hamele N, Frey N, Chou J, McAleavey L, Greene J, Paulson W. Male choice in the stream-anadromous stickleback complex. PLoS One 2012; 7:e37951. [PMID: 22701589 PMCID: PMC3372497 DOI: 10.1371/journal.pone.0037951] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Accepted: 04/30/2012] [Indexed: 12/04/2022] Open
Abstract
Studies of mating preferences and pre-mating reproductive isolation have often focused on females, but the potential importance of male preferences is increasingly appreciated. We investigated male behavior in the context of reproductive isolation between divergent anadromous and stream-resident populations of threespine stickleback, Gasterosteus aculeatus, using size-manipulated females of both ecotypes. Specifically, we asked if male courtship preferences are present, and if they are based on relative body size, non-size aspects of ecotype, or other traits. Because male behaviors were correlated with each other, we conducted a principal components analysis on the correlations and ran subsequent analyses on the principal components. The two male ecotypes differed in overall behavioral frequencies, with stream-resident males exhibiting consistently more vigorous and positive courtship than anadromous males, and an otherwise aggressive behavior playing a more positive role in anadromous than stream-resident courtship. We observed more vigorous courtship toward smaller females by (relatively small) stream-resident males and the reverse pattern for (relatively large) anadromous males. Thus size-assortative male courtship preferences may contribute to reproductive isolation in this system, although preferences are far from absolute. We found little indication of males responding preferentially to females of their own ecotype independent of body size.
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Affiliation(s)
- Jeffrey S McKinnon
- Department of Biology, East Carolina University, Greenville, North Carolina, United States of America.
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70
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Snowberg LK, Bolnick DI. Partitioning the effects of spatial isolation, nest habitat, and individual diet in causing assortative mating within a population of threespine stickleback. Evolution 2012; 66:3582-94. [PMID: 23106720 PMCID: PMC3869085 DOI: 10.1111/j.1558-5646.2012.01701.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Assortative mating is measured as a phenotypic or genotypic correlation between mates. Although biologists typically view assortative mating in terms of mate preference for similar partners, correlations between mates can also arise from phenotypic spatial structure arising from spatial isolation or habitat preferences. Here, we test whether diet-assortative mating within an ecologically variable population of threespine stickleback results from small-scale geographic isolation or microhabitat preference. We find evidence for assortative mating in the form of a positive correlation between mated pairs' diets (measured using stable isotopes). Stable isotopes reveal diet differences between different nesting areas and among individuals using different nest habitat within a nesting area. This spatial segregation of diet types should generate some assortative mating, but is insufficient to explain the observed assortment strength. Significant male-female isotope correlations remain after controlling for spatial variables. We therefore conclude that sticklebacks' diet-assortative mating arises from additional behavioral preference. More generally, our results illustrate the point that spatial segregation can only drive appreciable levels of phenotypic assortative mating when environment-phenotype correlations are parallel and strong in both sexes. Consequently, intraspecific assortative mating may typically entail mating preferences rather than just spatial cosegregation of phenotypes.
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Affiliation(s)
- L K Snowberg
- Department of Ecology, Evolution, and Behavior, University of Texas at Austin, Austin, Texas 78712, USA.
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71
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Abstract
Early acquisition of mate preferences or mate-preference learning is associated with signal diversity and speciation in a wide variety of animal species. However, the diversity of mechanisms of mate-preference learning across taxa remains poorly understood. Using the butterfly Bicyclus anynana we uncover a mechanism that can lead to directional sexual selection via mate-preference learning: a bias in learning enhanced ornamentation, which is independent of preexisting mating biases. Naïve females mated preferentially with wild-type males over males with enhanced wing ornamentation, but females briefly exposed to enhanced males mated significantly more often with enhanced males. In contrast, females exposed to males with reduced wing ornamentation did not learn to prefer drab males. Thus, we observe both a learned change of a preexisting mating bias, and a bias in ability to learn enhanced male ornaments over reduced ornaments. Our findings demonstrate that females are able to change their preferences in response to a single social event, and suggest a role for biased learning in the evolution of visual sexual ornamentation.
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72
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Abstract
Character displacement occurs when competition for either resources or successful reproduction imposes divergent selection on interacting species, causing divergence in traits associated with resource use or reproduction. Here, we describe how character displacement can be mediated either by genetically canalized changes (i.e., changes that reflect allelic or genotype frequency changes) or by phenotypic plasticity. We also discuss how these two mechanisms influence the tempo of character displacement. Specifically, we suggest that, under some conditions, character displacement mediated by phenotypic plasticity might occur more rapidly than that mediated by genetically canalized changes. Finally, we describe how these two mechanisms may act together and determine character displacement's mode, such that it proceeds through an initial phase in which trait divergence is environmentally induced to a later phase in which divergence becomes genetically canalized. This plasticity-first hypothesis predicts that character displacement should be generally mediated by ancestral plasticity and that it will arise similarly in multiple, independently evolving populations. We conclude by highlighting future directions for research that would test these predictions.
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Affiliation(s)
- David W Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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73
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KOZAK GM, BOUGHMAN JW. Plastic responses to parents and predators lead to divergent shoaling behaviour in sticklebacks. J Evol Biol 2012; 25:759-69. [DOI: 10.1111/j.1420-9101.2012.02471.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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74
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Abstract
Populations that have independently evolved reproductive isolation from their ancestors while remaining reproductively cohesive have undergone parallel speciation. A specific type of parallel speciation, known as parallel ecological speciation, is one of several forms of evidence for ecology's role in speciation. In this paper we search the literature for candidate examples of parallel ecological speciation in plants. We use four explicit criteria (independence, isolation, compatibility, and selection) to judge the strength of evidence for each potential case. We find that evidence for parallel ecological speciation in plants is unexpectedly scarce, especially relative to the many well-characterized systems in animals. This does not imply that ecological speciation is uncommon in plants. It only implies that evidence from parallel ecological speciation is rare. Potential explanations for the lack of convincing examples include a lack of rigorous testing and the possibility that plants are less prone to parallel ecological speciation than animals.
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Divergent Selection and Then What Not: The Conundrum of Missing Reproductive Isolation in Misty Lake and Stream Stickleback. INTERNATIONAL JOURNAL OF ECOLOGY 2012. [DOI: 10.1155/2012/902438] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In ecological speciation, reproductive isolation evolves as a consequence of adaptation to different selective environments. A frequent contributor to this process is the evolution of positive assortative mate choice between ecotypes. We tested this expectation for lake and inlet stream threespine stickleback (Gasterosteus aculeatus) from the Misty system (Vancouver Island, Canada), which show strong genetically based adaptive divergence and little genetic exchange in nature. This, and work on other stickleback systems, led us to expect positive assortative mating. Yet, our standard “no-choice” laboratory experiment on common-garden fish revealed no evidence for this—despite divergence in traits typically mediating assortative mating in stickleback. These results remind us that divergent natural selection may not inevitably lead to the evolution of positive assortative mate choice. The apparent lack of strong and symmetric reproductive barriers in this system presents a conundrum: why are such barriers not evident despite strong adaptive divergence and low gene flow in nature?
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