Phylogenetic and Geographic Patterns in the Diversity of Peatmosses(Sphagnum)

Duke University, Durham NC

Investigators

Abstract

0075611 Shaw Peatmosses (plants of the bryophyte genus Sphagnum) are a dominant component of many Northern and Southern Hemisphere ecosystems. Sphagnum-dominated habitats are ecologically important in terms of regional hydrology, and peat accumulation is of profound significance to global carbon budgets and therefore global climates. Sphagnum-dominated peatlands are most prominent in boreal regions where huge deposits of partially decomposed peat accumulate, and most people associate Sphagnum with such northern hemisphere habitats. Nonetheless, species of Sphagnum are also diverse in the tropics, and one evolutionary hypothesis suggests that South America is the center of peatmoss diversity. Dr. Jonathan Shaw of Duke University and colleagues are studying the taxonomic and phylogenetic diversity of the 200-450 species of Sphagnum in order to investigate these and other ideas about the patterns of species diversity worldwide in the genus. The project makes extensive use of DNA sequencing, of both nuclear and chloroplast genes, as sources of evidence of phylogenetic (genealogical) relatedness and to estimate levels of genetic and genomic diversity within sublineages of Sphagnum. Molecular and morphological lines of evidence will be combined in studies of presumptive cases of hybridization and of cryptic species, where similar morphologies are thought to obscure significant genetic divergence. The project will lead to an improved infrageneric classification for the hundreds of species worldwide of Sphagnum, and contribute to understanding the mechanisms of peatmoss diversification over geological time.