Translator Disclaimer
1 August 2008 Genetics of Intrinsic Postzygotic Isolation in a Circumpolar Plant Species, Draba Nivalis (Brassicaceae)
Inger Skrede, Christian Brochmann, Liv Borgen, Loren H. Rieseberg
Author Affiliations +

Sterility barriers, ranging from incomplete to fully developed, were recently demonstrated within taxonomic species of the genus Draba, suggesting the existence of numerous, cryptic biological species. Because these taxa are predominately selfers and of Pleistocene origin, it was concluded that hybrid sterility evolved quickly and possibly by genetic drift. Here we used genetic mapping and QTL analyses to determine the genetic basis of hybrid sterility between geographically distant populations of one of these taxonomic species, Draba nivalis. Fifty microsatellite loci were mapped, and QTL analyses identified five loci underlying seed fertility and two underlying pollen fertility. Four of five seed fertility QTLs reduced fertility in heterozygotes, an observation most consistent with drift-based fixation of underdominant sterility loci. However, several nuclear–nuclear interactions were also found, including two that acted like reciprocal translocations with lowest fitness in double heterozygotes, and two that had a pattern of fitness consistent with Bateson–Dobzhansky–Muller incompatibilities. In contrast, pollen fertility QTLs exhibited additive inheritance, with lowest fertility associated with the paternal allele, a pattern of inheritance suggestive of cytonuclear incompatibilities. The results imply that multiple genetic mechanisms underlie the rapid evolution of reproductive barriers in Draba.

Inger Skrede, Christian Brochmann, Liv Borgen, and Loren H. Rieseberg "Genetics of Intrinsic Postzygotic Isolation in a Circumpolar Plant Species, Draba Nivalis (Brassicaceae)," Evolution 62(8), 1840-1851, (1 August 2008).
Received: 18 November 2007; Accepted: 26 April 2008; Published: 1 August 2008

This article is only available to subscribers.
It is not available for individual sale.

Get copyright permission
Back to Top