|Ellstrand, Norman - UC RIVERSIDE|
Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2008
Publication Date: November 5, 2008
Repository URL: http://www.springerlink.com/content/8g1x6m766t38u8pu/?p=647b5917e0ad4ab3bf5f122b739c322a&pi=7
Citation: Schierenbeck, K.A., Ellstrand, N.C. 2008. Hybridization and Evolution of Invasiveness in Plants and Other Organisms. Biological Invasions 11:1093-1105. Interpretive Summary: The introduction of non-native species can result in the breeding among closely-related species or populations that have historically occurred in different areas. This genetic mixture can result in the formation of new genetic forms that are more invasive than either one of their parental species or populations. Earlier work by these authors (K. A. Schierenbeck and N. C. Ellstrand) was the impetuous for much research on this topic. We reviewed earlier cases of this phenomenon and presented many new examples. We conclude that multiple introductions and subsequent gene flow provide a serious mode of the evolution of new invasive genotypes. Additionally, this process presents a serious problem for control efforts due to the novel genetic variation found in these new evolved populations.
Technical Abstract: Less than a decade ago, we proposed that hybridization could serve as a stimulus for the evolution of invasiveness in plants (Ellstrand and Schierenbeck Proc Nat Acad Sci USA 97:7043–7050, 2000). A substantial amount of research has taken place on that topic since the publication of that paper, stimulating the symposium that makes up this special issue. Here we present an update of this emergent field, based both on the papers in this volume and on the relevant literature. We reevaluate the lists that we presented in our earlier paper of reports in which hybridization has preceded the evolution of invasiveness. We discard a few cases that were found to be in error, published only as abstracts, or based on personal communication. Then we augment the list from examples in this volume and a supplementary literature search. Despite the omissions, the total number of cases has increased. Many have been strengthened. We add a list of cases in which there has been evidence that intra-taxon hybridization has preceded the evolution of invasiveness. We also provide a number of examples from organisms other than plants. We consider how our examples suggest mechanisms whereby hybridization may act to stimulate the evolution of invasiveness. Hybridization does not represent the only evolutionary pathway to invasiveness, but it is one that can explain why the appearance of invasiveness often involves a long lag time and/or multiple introductions of exotics.