RAPID EVOLUTION OF REPRODUCTIVE ISOLATION BETWEEN INCIPIENT OUTCROSSING AND SELFING CLARKIA SPECIES

A major goal of speciation research is to understand the processes involved in the earliest stages of the evolution of reproductive isolation (RI). One important challenge has been to identify systems where lineages have very recently diverged and opportunities for hybridization are present. We cond...

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Bibliographic Details
Published inEvolution Vol. 68; no. 10; pp. 2885 - 2900
Main Authors Briscoe Runquist, Ryan D., Chu, Eric, Iverson, Justin L., Kopp, Jason C., Moeller, David A.
Format Journal Article
LanguageEnglish
Published United States Blackwell Publishing Ltd 01.10.2014
Wiley Subscription Services, Inc
Oxford University Press
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Summary:A major goal of speciation research is to understand the processes involved in the earliest stages of the evolution of reproductive isolation (RI). One important challenge has been to identify systems where lineages have very recently diverged and opportunities for hybridization are present. We conducted a comprehensive examination of the components of RI across the life cycle of two subspecies of Clarkia xantiana, which diverged recently (ca. 65,000 bp). One subspecies is primarily outcrossing, but self-compatible, whereas the other is primarily selfing. The subspecies co-occur in a zone of sympatry but hybrids are rarely observed. Premating barriers resulted in nearly complete isolation in both subspecies with flowering time and pollinator preference (for the outcrosser over the selfer) as the strongest barriers. We found that the outcrosser had consistently more competitive pollen, facilitating hybridization in one direction, but no evidence for pollen-pistil interactions as an isolating barrier. Surprisingly, postzygotic isolation was detected at the stage of hybrid seed development, but in no subsequent life stages. This crossing barrier was asymmetric with crosses from the selfer to outcrosser most frequently failing. Collectively, the results provide evidence for rapid evolution of multiple premating and postzygotic barriers despite a very recent divergence time.
Bibliography:ark:/67375/WNG-W13TKNNR-1
ArticleID:EVO12488
National Science Foundation - No. DEB-1025004
istex:0E0D21B43143C5177B470C18E49D6783593278DB
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0014-3820
1558-5646
DOI:10.1111/evo.12488