Location: Sunflower Research
Title: Phylogeny of Cirsium spp. in North America: host specificity does not follow phylogeny Authors
Submitted to: PLANTS
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 16, 2012
Publication Date: October 24, 2012
Citation: Bodo Slotta, T.A., Horvath, D.P., Foley, M.E. 2012. Phylogeny of Cirsium spp. in North America: host specificity does not follow phylogeny. PLANTS. 1:61-73. Interpretive Summary: Thistles and particularly Canada thistle is a widespread and invasive weed found in natural areas, cropland, and rangelands. Population genetic analysis of several native and non-native thistles of the Great Plains of the United States indicated that there has been no cross-hybridization between Canada thistle and thistles native to North America. In addition, mapping the co-occurrence of thistles with several insects introduced long ago as biological control agents indicates the agents have low levels of preference for specific types of thistles. The low level of preference supports the concept of examining taxonomic as well as ecological factors prior to the release of new insect biological control agents.
Technical Abstract: Weedy invasive Cirsium spp. are widespread in temperate regions of North America and some of their biological control agents have attacked native Cirsium spp. A phylogenetic tree was developed from DNA sequences for the internal transcribed spacer and external transcribed spacer regions from native and non-native Great Plains Cirsium spp. and other thistles to determine if host specificity follows phylogeny. The monophyly of Cirsium spp. and Carduus within the tribe Cardinae was confirmed with native North American and European lineages of the Cirsium spp. examined. We did not detect interspecific hybridization between the introduced invasive and the native North American Cirsium spp. Selected host-biological control agent interactions were mapped onto the phylogenic tree derived by maximum likelihood analysis to examine the co-occurrence of known hosts with biological control agents. Within Cirsium-Cardueae, the insect biological control agents do not associate with host phylogenetic lines indicating little taxonomic preference for specific hosts. Thus, genetic variation within hosts located in proposed release location as well as ecological factors like geographical proximity to related plants should be fully tested prior to the release of potential biological control agents.