GENETIC DIFFERENTIATION AND SELECTION AGAINST MIGRANTS IN EVOLUTIONARILY REPLICATED EXTREME ENVIRONMENTS |
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Authors: | Martin Plath Markus Pfenninger Hannes Lerp Rüdiger Riesch Christoph Eschenbrenner Patrick A Slattery David Bierbach Nina Herrmann Matthias Schulte Lenin Arias–Rodriguez Jeane Rimber Indy Courtney Passow Michael Tobler |
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Institution: | 1. J. W. Goethe‐University Frankfurt/M., Evolutionary Ecology Group, , Frankfurt, a. M., Germany;2. J.W. Goethe‐University Frankfurt/M., Biodiversity & Climate Research Centre, Molecular Ecology Group, Biocampus Siesmayerstra?e, , 60323 Frankfurt, a. M., Germany;3. Department of Biology & W. M. Keck Center for Behavioral Biology, North Carolina State University, , Raleigh, North Carolina, 27695;4. Department of Animal & Plant Sciences, University of Sheffield, , Western Bank, Sheffield, S10 2TN United Kingdom;5. División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco (UJAT), C.P., , 86150 Villahermosa, Tabasco, Mexico;6. University of Potsdam, Institute of Biochemistry & Biology, Unit of Animal Ecology, , 1, 14469 Potsdam, Germany;7. Department of Zoology, Oklahoma State University, , Stillwater, Oklahoma, 74078 |
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Abstract: | We investigated mechanisms of reproductive isolation in livebearing fishes (genus Poecilia) inhabiting sulfidic and nonsulfidic habitats in three replicate river drainages. Although sulfide spring fish convergently evolved divergent phenotypes, it was unclear if mechanisms of reproductive isolation also evolved convergently. Using microsatellites, we found strongly reduced gene flow between adjacent populations from different habitat types, suggesting that local adaptation to sulfidic habitats repeatedly caused the emergence of reproductive isolation. Reciprocal translocation experiments indicate strong selection against immigrants into sulfidic waters, but also variation among drainages in the strength of selection against immigrants into nonsulfidic waters. Mate choice experiments revealed the evolution of assortative mating preferences in females from nonsulfidic but not from sulfidic habitats. The inferred strength of sexual selection against immigrants (RIs) was negatively correlated with the strength of natural selection (RIm), a pattern that could be attributed to reinforcement, whereby natural selection strengthens behavioral isolation due to reduced hybrid fitness. Overall, reproductive isolation and genetic differentiation appear to be replicated and direct consequences of local adaptation to sulfide spring environments, but the relative contributions of different mechanisms of reproductive isolation vary across these evolutionarily independent replicates, highlighting both convergent and nonconvergent evolutionary trajectories of populations in each drainage. |
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Keywords: | Ecological speciation isolation‐by‐adaptation local adaptation Poecilia mexicana reinforcement sexual isolation |
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