Bryological and Lichenological Section/ABLS
Zhou, Ping , Shaw, A.J. , Menzel, Florian .
Systematics and speciation of Sphagnum macrophyllum and S. cribrosum.
TO clarify long-standing disagreement about the taxonomic status of and phylogentic relationship between Sphagnum macrophyllum and S. cribrosum, twenty-five samples of S. macrophyllum and twenty-four of S. cribrosum, including the “wave-form” morphotype, were sampled from ten states of the eastern U.S. The data set included multiple samples from three populations in North Carolina: seven plants of S. macrophyllum from a site in the Green Swamp, plus 15 plants of normal and “wave-form” morphotypes of S. cribrosum from Singletary Lake. Three anonymous genomic regions (RAPDa, RAPDb and RAPDf) were sequenced for all the samples; two (nuclear) LEAFY introns (LEAFY1 and LEAFY2) and one chloroplast locus (TrnG) were sequenced for all the samples excluding the twenty-two within-population North Carolina samples. The results showed that S. macrophyllum and S. cribrosum are reciprocally monophyletic with parsimony bootstrap support and significant Bayesian posterior probabilities. Genetic analyses based on the neutral coalescence model using summary statistics suggest that the simplest allopatric speciation model—isolation model with no subsequent gene flow and constant population sizes cannot be rejected. However, the data do suggest asymmetric gene flow between the two species since divergence under another speciation model-- "isolation with migration", which is implemented in Bayesian framework using Markov chain Monte Carlo method.
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1 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 10:15 AM