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

泥炭藓(苔藓属植物)是许多北半球和南半球生态系统的主要组成部分。泥炭占主导地位的生境在区域水文方面具有重要的生态意义，泥炭的积累对全球碳收支和全球气候具有深远的意义。泥炭藓占主导地位的泥炭地最突出的是北部地区，那里堆积着大量部分分解的泥炭，大多数人将泥炭土与北半球的这种栖息地联系在一起。尽管如此，泥炭草属的物种在热带地区也是多种多样的，一种进化假说表明，南美洲是泥炭苔类物种多样性的中心。杜克大学的乔纳森·肖博士和他的同事们正在研究200-450种泥炭藻属的分类学和系统发育多样性，以调查这些和其他关于该属世界范围内物种多样性模式的想法。该项目广泛使用核基因和叶绿体基因的DNA测序，作为系统发育(谱系)亲缘关系的证据来源，并估计泥炭藻亚系内的遗传和基因组多样性水平。分子和形态证据线将结合在对杂交和隐蔽物种的推定案例的研究中，在这些案例中，相似的形态被认为掩盖了显著的遗传差异。该项目将改进世界范围内数百种泥炭藓的属下分类，并有助于了解泥炭藓随地质时间变化的机制。

0075611Shaw 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.