Molecular Systematics of the Zygnematales

Zygnematales是绿藻中种类最多的成员，有55个属约7,000种。目前关于绿色植物间系统发育关系的假说认为该目是高等植物的姊妹分类群。然而，Zygnematales成员之间的系统发育关系是有问题的。这在一定程度上是因为个体受到相当大的形态变化的影响，这取决于它们发生的环境和高度可塑性的染色体数量。PIS建议检查不受这种波动影响的基因，以开发这一目藻类的系统发育模型。推导出的模型应该对陆地植物的起源和辐射以及可能对陆地栖息地的占领起作用的因素有影响。要考虑的基因都位于叶绿体中。这套基因已被证明对阐明各种陆地植物群的系统发育很有用。因此，PI产生的数据集可以直接应用于所有其他绿色植物的比较。

Zygnematales is the most diverse member of the green algae with about 7,000 species in 55 genera. Current hypotheses of phylogenetic relationships among the green plants places this order as the sister taxon of the higher plants. However, phylogenetic relationships among the members of Zygnematales are problematic. This results in part because the individuals are subject to considerable morphological modification contingent upon the environment in which they occur and upon the chromosome number which is highly plastic. The PIs propose to examine genes that are not subject to such fluctuations in order to develop a phylogenetic model for this order of algae. The derived model should have implications for the origin and radiation of the land plants and the factors that may have played a role in the occupation of terrestrial habitats. The genes to be considered are all located in the chloroplast. This suite of genes has proven useful in elucidating the phylogenies of a variety of land plant groups. Therefore, the data set produced by the PIs can be directly applied to comparisons of all other green plants.