Sexual isolation promotes divergence between parapatric lake and stream stickleback

Berner, Daniel and Ammann, Matthias and Spencer, Eleanor and Rüegg, Attila and Lüscher, Daniel and Moser, Dario. (2017) Sexual isolation promotes divergence between parapatric lake and stream stickleback. Journal of Evolutionary Biology, 30. pp. 401-411.

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Official URL: http://edoc.unibas.ch/56084/

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Speciation can be initiated by adaptive divergence between populations in ecologically different habitats, but how sexually based reproductive barriers contribute to this process is less well understood. We here test for sexual isolation between ecotypes of threespine stickleback fish residing in adjacent lake and stream habitats in the Lake Constance basin, Central Europe. Mating trials exposing females to pairings of territorial lake and stream males in outdoor mesocosms allowing for natural reproductive behaviour reveal that mating occurs preferentially between partners of the same ecotype. Compared to random mating, this sexual barrier reduces gene flow between the ecotypes by some 36%. This relatively modest strength of sexual isolation is surprising because comparing the males between the two ecotypes shows striking differentiation in traits generally considered relevant to reproductive behaviour (body size, breeding coloration, nest size). Analysing size differences among the individuals in the mating trials further indicates that assortative mating is not related to ecotype differences in body size. Overall, we demonstrate that sexually based reproductive isolation promotes divergence in lake–stream stickleback along with other known reproductive barriers, but we also caution against inferring strong sexual isolation from the observation of strong population divergence in sexually relevant traits.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Integrative Biologie > Evolutionary Biology (Salzburger)
UniBasel Contributors:Berner, Daniel
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Wiley-Blackwell Publishing
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:19 Oct 2017 09:01
Deposited On:19 Oct 2017 09:01

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