MSA - Systematics/Evolution
Kleine, Chris , McClean, Terry , Miller, Steven L. .
Three disjunct ectomycorrhizal Russula species from Africa and Madagascar.
Species in the genus Russula are common ectomycorrhizal symbionts in caesalpinioid legume and Uapaca forests of Africa and Madagascar. However, the biogeographical factors affecting the distribution of ectomycorrhizal fungi in the Old and New World tropics are largely unknown. As part of a preliminary analysis of the biogeographical history of African and Malagasy ectomycorrhizal species, ITS and atp6 sequences of three Russula species found in both continental Africa and Madagascar were analyzed using MP, ML, and Bayesian methods to assess geographic structure and to estimate diverge times. The ITS sequence for African and Malagasy populations of R. pseudocarmicina differed by a mean of 5.1% and the atp6 sequence differed by 2.8%; all methods of phylogenetic analysis produced well-supported geographically defined clades. African and Malagasy clades were also supported for R. discopus and ITS and atp6 sequences differed by 4.0% and 1.8%, respectively. R. ochraceorivulosa also exhibited geographic structure, although the ITS (1.4%) and atp6 (0.17%) sequence differences were smaller than the other two species. Additionally, four of the Malagasy specimens of R. ochraceorivulosa shared an atp6 haplotype with an African specimen. While differences in ITS and atp6 evolutionary rates are possible, these results suggested that R. ochraceorivulosa may have a biogeographical history that differs from the other species. The lack of fossil evidence for taxa closely related to these fungi necessitated the use of more distantly related groups to estimate divergence times. These estimates suggested that African and Malagasy populations diverged well after the separation of the Gondwanan landmass 160 Mya.
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1 - University of Wyoming, Department of Botany, 1000 E. University Ave., Laramie, WY, 82071, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Cottonwood A/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 4:30 PM