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Natural and sexual selection against immigrants maintains differentiation among micro‐allopatric populations
Author(s) -
TOBLER M.,
RIESCH R.,
TOBLER C. M.,
SCHULZMIRBACH T.,
PLATH M.
Publication year - 2009
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2009.01844.x
Subject(s) - biology , parapatric speciation , allopatric speciation , ecological speciation , ecology , habitat , ecological selection , reproductive isolation , local adaptation , natural selection , population , cave , genetic algorithm , gene flow , adaptation (eye) , evolutionary biology , genetic variation , biochemistry , demography , neuroscience , sociology , gene
Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence lead to speciation. But what mechanisms contribute to reproductive isolation among diverging populations? We tested for natural and sexual selection against immigrants in a fish species inhabiting (and adapting to) nonsulphidic surface habitats, sulphidic surface habitats and a sulphidic cave. Gene flow is strong among sample sites situated within the same habitat type, but low among divergent habitat types. Our results indicate that females of both sulphidic populations discriminate against immigrant males during mate choice. Furthermore, using reciprocal translocation experiments, we document natural selection against migrants between nonsulphidic and sulphidic habitats, whereas migrants between sulphidic cave and surface habitats did not exhibit increased mortality within the same time period. Consequently, both natural and sexual selection may contribute to isolation among parapatric populations, and selection against immigrants may be a powerful mechanism facilitating speciation among locally adapted populations even over very small spatial distances.