Molecular Ecology and Evolution
Barrett, Craig F. , Freudenstein, John , Taylor, D. Lee .
Host associations of the epiparasitic Striped Coralroot orchid complex.
Corallorhiza striata Lindley is a mycoheterotrophic orchid species complex that shows considerable variation in size, flower shape, phenology, and color across its North American range from Mexico to Canada. The complex also contains an endangered species, C. bentleyi Freudenstein, native to the Appalachian Mountains of Virginia and West Virginia, USA. Members of this species complex associate with taxa in the basidiomycete family Thelephoraceae. However, very little is known about the patterns of association between C. striata and fungal hosts across North America. We used DNA sequencing for 107 individual orchids (rbcL, rpl32-trnL) and their associated fungi (ITS) from 42 populations across North America to test hypotheses of: 1) strict host specificity of orchid clades and haplotypes on fungal clades or haplotypes, and 2) independence of orchid and fungal phylogenies. GenBank BLAST searches indicated that all C. striata and C. bentleyi fungal associates shared high identity with ectomycorrhizal Tomentella spp., all most closely matching Tomentella fuscocinerea. Orchid and fungal gene trees were significantly incongruent, but not independent of one another. Also, four main plastid DNA clades/taxonomic groupings associated with divergent sets of tomentelloid fungi; especially the Californian clade, in which 15 of 16 accessions grouped with a unique fungal clade. The pattern observed within the C. striata complex most closely fits a geographic mosaic model of associations in terms of specificity. These findings have important implications for the conservation of C. striata and the endangered C. bentleyi.
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1 - Ohio State University, Department of Evolution, Ecology, and Organismal Biology, OSU Herbarium (OS), Museum of Biological Diversity, 1315 Kinnear Rd., Columbus, Ohio, 43212, USA
2 - Ohio State University, Department of Evolution, Ecology, and Organismal Biology, University Herbarium, 1315 Kinnear Rd., Columbus, Ohio, 43212, USA
3 - University of Alaska Fairbanks, Institute of Arctic Biology, 311 Irving I, 902 N Koyukuk Drive, PO Box 757000, Fairbanks, AK, 99775-7000, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Maybird/Cliff Lodge - Level C
Date: Tuesday, July 28th, 2009
Time: 8:15 AM