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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGY AND MANAGEMENT OF INVASIVE WEEDS IN THE WESTERN UNITED STATES

Location: Exotic and Invasive Weeds Research

Title: Multigene analysis suggests ecological speciation in the fungal pathogen Claviceps purpurea

Authors
item Douhan, Greg - UC RIVERSIDE
item Smith, Matt - UC DAVIS
item Huyrn, K - UC RIVERSIDE
item Westbrook, A - UC DAVIS
item Beerli, P - FLORIDA STATE UNIV.
item Fisher, Alison

Submitted to: Molecular Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 21, 2008
Publication Date: October 11, 2008
Citation: Douhan, G.W., Smith, M.E., Huyrn, K.L., Westbrook, A., Beerli, P., Fisher, A.J. 2008. Multigene analysis suggests ecological speciation in the fungal pathogen Claviceps purpurea. Molecular Ecology. 17:2276-2286.

Interpretive Summary: The ergot fungus is an important pathogen of grasses and source of novel chemical compounds. Three groups within this species have been recognized based on habitat association, morphology, and alkaloid production. These groups have further been supported by genetic markers, suggesting this species may be more accurately described as a species complex. In this study, we used a multi-gene approach to test for speciation within the ergot fungus using DNA sequences. Our results suggest that these fungi are in the process of speciation and we argue that this process is driven by adaptations to ecological habitats; one group is associated with terrestrial grasses, the second group is found in wet and shady environments, and the third group is found in salt marsh habitats. All divergent ecotypes can coexist with no obvious physical barriers to prevent gene flow. However, our results suggest that no genetic exchange is occurring between these divergent groups.

Technical Abstract: Claviceps purpurea is an important pathogen of grasses and source of novel chemical compounds. Three groups within this species (G1, G2, and G3) have been recognized based on habitat association, sclerotia and conidia morphology, and alkaloid production. These groups have further been supported by genetic markers, suggesting this species may be more accurately described as a species complex. In this study, we used a multi-gene approach to test for speciation within C. purpurea using DNA sequences. We found that C. purpurea sensu lato appears to be in the early stages of speciation. The G1 types are significantly divergent from the G2/G3 types based on each of the three loci and the combined dataset, whereas the G2/G3 types are more integrated with one another. Our results suggest that these fungi are in the process of speciation and we argue that this process is driven by adaptations to ecological habitats; G1 isolates are associated with terrestrial grasses, G2 isolates are found in wet and shady environments, and G3 isolates are found in salt marsh habitats. All divergent ecotypes can coexist in sympatric populations with no obvious physical barriers to prevent gene flow. However, our results suggest that no genetic exchange is occurring between these divergent groups.

Last Modified: 10/1/2014
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