PRF: Cladistic Biogeography of the Genus Gleditsia (Leguminosae)

一个多世纪以来，东亚温带和北美东部的植物区系有显著的相似之处。尽管有异常健康的化石记录，但我们远远不是一个普遍的生物地理学假说，它将被证明在许多不同的分类群中是可靠的。解决这一问题的最具信息量的方法是将对遗传差异的估计(最好是针对几个不同的数据集)与分支和生物地理分析的显式方法相结合。本文描述了木本植物皂角属(豆科：皂角亚科)的这种方法，该属包含两个假设的东亚-北美东部替代种对，以及其他洲内和洲际分离。这项研究将首先使用不同分子数据集的分支分析来识别假定的单系类群。将构建区域分支图，以辨别单系类群中的洲内和洲际分离。对东亚-北美东部分离(和其他)起源的相互竞争的生物地理假说(特别是扩散和替代)的检验将从区域分支图的拓扑结构以及分子数据提供的遗传分化估计得出。因此，皂角属将作为其他属类似方法的模式，最终目的是了解其他北半球第三纪分离的起源和生物地理历史。

The remarkable floristic similarities between temperate eastern Asia and eastern North America have been recognized for over a century. Despite an unusually healthy fossil record, we are far from a general biogeographic hypothesis that will prove to be robust across many distinct taxa. The most informative approach to this problem will combine estimates of genetic divergence, preferably for several different data sets, with explicit methods of cladistic and biogeographic analysis. Such an approach is described herein for the woody genus Gleditsia (Leguminosae: Caesalpinioideae), which contains two hypothesized eastern Asian-eastern North American vicariad species-pairs, in addition to other intra- and intercontinental disjunctions. The study will first use cladistic analysis of different molecular data sets to recognize putative monophyletic groups. Area cladograms will be constructed to discern intra- and intercontinental disjunctions within monophyletic groups. Tests of competing biogeographic hypotheses (especially dispersal vs. vicariance) for the origin of eastern Asian-eastern North American disjunctions (and others) will derive from the topology of area cladograms coupled with estimates of genetic divergence provided by the molecular data. Gleditsia will thus serve as a model for similar approaches in other genera, with the ultimate objective being to understand the origins and biogeographic history of other northern hemisphere Tertiary disjunctions.