Freudenstein, John , Barrett, Craig F. .
Biogeography and fungal relationships in the Corallorhiza odontorhiza-wisteriana group (Orchidaceae).
Two species of Corallorhiza have unlobed lips and thin-textured perianth parts -- C. wisteriana and C. odontorhiza. The former is spring-flowering, ranging from Mexico across the United States. Corallorhiza odontorhiza is very similar in morphology, but flowers at the end of the growing season, in autumn, and has much smaller flowers. It also ranges from Mexico northward, but is only present in the eastern portion of the US and Canada. As part of a broader study of the genus, we examined variation in morphology, gene lineage, and fungal association in the context of geography for samples from across the species’ ranges. The analysis of over 80 accessions revealed that, for trnLF region and rpl32-trnL spacer sequences, accessions of C. odontorhiza form a clade, with two Mexican populations sister to the remainder from the north. Among the northern populations there is structure in the tree, but few clear geographic patterns emerge. Individuals from single populations are in some cases placed at some distance from each other in the tree, while in other cases fall together. Sister to the C. odontorhiza populations is a Mexican accession of C. wisteriana; the remainder of the C. wisteriana accessions are sister to this assemblage. Within C. wisteriana, two clades are sister – those from eastern North America and those from the west. The eastern and western groups are subtly distinguishable morphologically by orientation of the perianth parts. Surprisingly, eastern and western populations parasitize different Basidiomycete families – Russulaceae in the east and Thelephoraceae in the west. The pattern of fungal usage within Thelephoraceae did not show high specificity by orchid species, however, with many subclades of fungi being used by both orchid species. These patterns would be consistent with an origin of the group in Mexico, followed by migration northward and divergence in flowering times, with a major host shift to Russulaceae occurring in eastern C. wisteriana.
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1 - Ohio State University Herbarium, Dept of Evolution, Ecology and Organismal Biology, 1315 Kinnear Rd., Columbus, OH, 43212, USA
2 - Ohio State University Herbarium, Dept of Evolution, Ecology and Organismal Biology, 1315 Kinnear Rd., Columbus, Ohio, 43212, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 552B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 10:15 AM