Current Address: Department of Biology, St. Ambrose University, Davenport, IA 52803, USA.
Hybridization and invasion: one of North America’s most devastating invasive plants shows evidence for a history of interspecific hybridization
Article first published online: 27 AUG 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
Volume 3, Issue 1, pages 40–51, January 2010
How to Cite
Blair, A. C. and Hufbauer, R. A. (2010), Hybridization and invasion: one of North America’s most devastating invasive plants shows evidence for a history of interspecific hybridization. Evolutionary Applications, 3: 40–51. doi: 10.1111/j.1752-4571.2009.00097.x
- Issue published online: 17 DEC 2009
- Article first published online: 27 AUG 2009
- Received: 2 March 2009 Accepted: 28 July 2009
- amplified fragment length polymorphism;
- biological invasion;
- diffuse knapweed;
- spotted knapweed;
Hybridization has been hypothesized to influence invasion through the generation of novel phenotypes and/or increased levels of genetic variance. Based on morphology, hybrids between diffuse knapweed and spotted knapweed, two invasive plants in North America, are present in the invaded range. Some individuals within most diffuse knapweed sites in North America exhibit intermediate diffuse × spotted floral morphology. We examined hybridization at the molecular level, using amplified fragment length polymorphisms. Approximately a quarter of the assayed North American diffuse knapweed individuals exhibited evidence of introgression from spotted knapweed. However, plants with intermediate morphology did not show evidence of mixed ancestry more often than the plants with typical diffuse knapweed morphology. The high proportion of hybrid individuals in North American diffuse knapweed sites found here, combined with evidence from recent studies, suggests that diffuse knapweed was likely introduced with admixed individuals, and the hybrids are not newly created postintroduction. A century of backcrossing with diffuse knapweed has likely decoupled the relationship between morphology and admixture at the molecular level. In contrast to the scenario encountered in North America, in the native range where diploid diffuse and spotted knapweed overlap, hybrid swarms are common. In such sites, the floral phenotype aligns more closely with the genotype.