Genetic Bottlenecks Driven by Population Disconnection

Authors

  • THOMAS BROQUET,

    1. Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
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    • Current address: Team “Diversity and Connectivity in Coastal Marine Landscapes,” Roscoff Biological Station, UMR 7144 CNRS – Pierre and Marie Curie University, 29682 Roscoff, France, emailthomas.broquet@sb-roscoff.fr

  • SONIA ANGELONE,

    1. WSL Swiss Federal Research Institute, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland
    2. University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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  • JULIE JAQUIERY,

    1. Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
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    • Current address: INRA/Agrocampus Ouest, UMR 1099 BiO3P, Biology of Organisms and Populations Applied to Plant Protection, Domaine de la Motte, 35653 Le Rheu, France

  • PIERRE JOLY,

    1. UMR 5023 Ecology of Fluvial Hydrosystems, Bât. Darwin C, Université Lyon 1, F-69622 Villeurbanne, France
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  • JEAN-PAUL LENA,

    1. UMR 5023 Ecology of Fluvial Hydrosystems, Bât. Darwin C, Université Lyon 1, F-69622 Villeurbanne, France
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  • THIERRY LENGAGNE,

    1. UMR 5023 Ecology of Fluvial Hydrosystems, Bât. Darwin C, Université Lyon 1, F-69622 Villeurbanne, France
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  • SANDRINE PLENET,

    1. UMR 5023 Ecology of Fluvial Hydrosystems, Bât. Darwin C, Université Lyon 1, F-69622 Villeurbanne, France
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  • EMILIEN LUQUET,

    1. UMR 5023 Ecology of Fluvial Hydrosystems, Bât. Darwin C, Université Lyon 1, F-69622 Villeurbanne, France
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  • NICOLAS PERRIN

    1. Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
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Abstract

Abstract: Connectivity among populations plays a crucial role in maintaining genetic variation at a local scale, especially in small populations affected strongly by genetic drift. The negative consequences of population disconnection on allelic richness and gene diversity (heterozygosity) are well recognized and empirically established. It is not well recognized, however, that a sudden drop in local effective population size induced by such disconnection produces a temporary disequilibrium in allelic frequency distributions that is akin to the genetic signature of a demographic bottleneck. To document this effect, we used individual-based simulations and empirical data on allelic richness and gene diversity in six pairs of isolated versus well-connected (core) populations of European tree frogs. In our simulations, population disconnection depressed allelic richness more than heterozygosity and thus resulted in a temporary excess in gene diversity relative to mutation drift equilibrium (i.e., signature of a genetic bottleneck). We observed a similar excess in gene diversity in isolated populations of tree frogs. Our results show that population disconnection can create a genetic bottleneck in the absence of demographic collapse.

Abstract

ResumenLa conectividad entre poblaciones juega un papel crucial en el mantenimiento de la variación genética a escala local, especialmente en poblaciones pequeñas afectadas por la deriva génica. Las consecuencias negativas de la desconexión de la población sobre la riqueza alélica y la diversidad genética (heterocigosidad) están bien reconocidas y establecidas empíricamente. Sin embargo, no está bien reconocido que una disminución repentina en el tamaño poblacional efectivo inducida por tal desconexión produce un desequilibrio temporal en las distribuciones de frecuencias alélicas que es comparable con la firma genética de un cuello de botella demográfico. Para documentar este efecto, utilizamos simulaciones basadas en individuos y datos empíricos de la riqueza alélica y diversidad genética en seis pares de poblaciones aisladas deHyla arboreaversus poblaciones bien conectadas (núcleo). En nuestras simulaciones, la desconexión poblacional deprimió la riqueza alélica más que la heterocigosidad y por lo tanto resultó en un exceso temporal de diversidad genética en relación con el equilibrio por deriva mutacional (i. e., firma de un cuello de botella genético). Observamos un exceso similar en la diversidad genética en poblaciones aisladas de H. arbórea. Nuestros resultados muestran que la desconexión de la población puede crear un cuello de botella genético en la ausencia de un colapso demográfico.

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