Divergence along a steep ecological gradient in lake whitefish (Coregonus sp.)

Authors

  • P. VONLANTHEN,

    1. Division of Aquatic Ecology & Evolution, Institute of Ecology & Evolution, University of Bern, Bern, Switzerland
    2. Department of Fish Ecology & Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
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  • D. ROY,

    1. Department of Fish Ecology & Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
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  • A. G. HUDSON,

    1. Division of Aquatic Ecology & Evolution, Institute of Ecology & Evolution, University of Bern, Bern, Switzerland
    2. Department of Fish Ecology & Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
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  • C. R. LARGIADÈR,

    1. Institute of Clinical Chemistry, Inselspital, University Hospital, and University of Bern, Inselspital, Bern, Switzerland
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  • D. BITTNER,

    1. Computational and Molecular Population Genetics Lab (CMPG), Institute of Ecology & Evolution, University of Bern, Bern, Switzerland
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  • O. SEEHAUSEN

    1. Division of Aquatic Ecology & Evolution, Institute of Ecology & Evolution, University of Bern, Bern, Switzerland
    2. Department of Fish Ecology & Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
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Pascal Vonlanthen, Division of Aquatic Ecology & Evolution, Institute of Ecology & Evolution, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland.
Tel.: +41 (0)41 349 22 02; fax: +41 (0)41 349 21 68; e-mail: pascal.vonlanthen@eawag.ch

Abstract

To understand mechanisms structuring diversity in young adaptive radiations, quantitative and unbiased information about genetic and phenotypic diversity is much needed. Here, we present the first in-depth investigation of whitefish diversity in a Swiss lake, with continuous spawning habitat sampling in both time and space. Our results show a clear cline like pattern in genetics and morphology of populations sampled along an ecological depth gradient in Lake Neuchâtel. Divergent natural selection appears to be involved in shaping this cline given that trait specific PST-values are significantly higher than FST-values when comparing populations caught at different depths. These differences also tend to increase with increasing differences in depth, indicating adaptive divergence along a depth gradient, which persists despite considerable gene flow between adjacent demes. It however remains unclear, whether the observed pattern is a result of currently stable selection-gene flow balance, incipient speciation, or reverse speciation due to anthropogenic habitat alteration causing two formerly divergent species to collapse into a single gene pool.

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