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Evolution. 2019 Feb;73(2):245-261. doi: 10.1111/evo.13652. Epub 2018 Dec 12.

Ecological divergence plays an important role in strong but complex reproductive isolation in campions (Silene).

Author information

1
Department of Ecology and Genetics, Uppsala University, Norbyvägen 18 D, 75236, Uppsala, Sweden.
2
Current Address: Swedish Board of Agriculture, Vallgatan 8, 551 82, Jönköping, Sweden.
3
Department of Diversity and Evolution of Higher Plants, Institute of Ecology, Evolution and Diversity, Goethe-University, 60439, Frankfurt am Main, Germany.
4
Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.
5
ETH Zurich, Institute of Integrative Biology, Universitätstrasse 16, 8092, Zürich, Switzerland.
6
Current Address: Research Institute of Organic Agriculture FiBL, Department of Soil Sciences, Ackerstrasse 113, Box 219, 5070, Frick, Switzerland.

Abstract

New species arise through the evolution of reproductive barriers between formerly interbreeding lineages. Yet, comprehensive assessments of potential reproductive barriers, which are needed to make inferences on processes driving speciation, are only available for a limited number of systems. In this study, we estimated individual and cumulative strengths of seven prezygotic and six postzygotic reproductive barriers between the recently diverged taxa Silene dioica (L.) Clairv. and S. latifolia Poiret using both published and new data. A combination of multiple partial reproductive barriers resulted in near-complete reproductive isolation between S. dioica and S. latifolia, consistent with earlier estimates of gene flow between the taxa. Extrinsic barriers associated with adaptive ecological divergence were most important, while intrinsic postzygotic barriers had moderate individual strength but contributed only little to total reproductive isolation. These findings are in line with ecological divergence as driver of speciation. We further found extensive variation in extrinsic reproductive isolation, ranging from sites with very strong selection against migrants and hybrids to intermediate sites where substantial hybridization is possible. This situation may allow for, or even promote, heterogeneous genetic divergence.

KEYWORDS:

Adaptation; gene flow; germination; reproductive barrier; speciation

PMID:
30499144
DOI:
10.1111/evo.13652

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