RUI: Phylogenetic Analysis of Begoniaceae

伊萨卡学院的苏珊·斯文森博士与布鲁克林植物园(马克·特比特博士)和爱丁堡皇家植物园(理查德·贝特曼博士等)的合作者一起研究热带植物海棠科的分类和系统发育。海棠属已公布了1000多个命名种，在分类学上是复杂的，也是具有挑战性的。对这些热带植物的园艺兴趣导致了几个主要植物园的大量活着的收藏品，但对众多物种的分类通常依赖于一组有限的花和营养特征，许多形式之间的相似性被怀疑是在许多亚组中收敛或平行进化的。目前，海棠属约有80个组(种和属之间的等级)被识别，但主要是基于一些用于标本馆鉴定的关键特征。斯文森博士强调，要从数百个物种的样本中获取DNA序列数据，这些样本来自核或叶绿体基因区域，并得到她的合作者针对相同样本分类群的叶绿体或核数据的补充。本科生将积极参与研究的各个方面。形态和解剖特征方面的工作也将开始，最终将与分子数据库整合。尽管被认为是热带植被的不同组成部分，但秋海棠科并不为人所知，目前的分类很少深入了解它们的历史生物地理或进化的有趣特征，如雌雄异株和相关的授粉(一个物种内分离的雄花和雌株)。在最近基于分子的系统发育中，单物种属Hillebrdia的基本位置特别令人困惑；这种夏威夷特有的物种可能是从地质上最近引入这些岛屿的，或者是更古老的遗迹。当以新的DNA序列数据为基础，并与传统的形态和染色体数据相结合，为该群体建立框架系统发育或家谱时，这些和其他生物学问题将得到回答。

9815816Swensen Working with collaborators at the Brooklyn Botanic Garden (Dr. Mark Tebbitt) and the Royal Botanic Gardens, Edinburgh (Dr. Richard Bateman and others), Dr. Susan Swensen at Ithaca College is studying the taxonomy and phylogeny of the tropical plant family Begoniaceae. With over a thousand named species published for the genus Begonia itself, the group is taxonomically complex and challenging. Horticultural interest in these tropical plants has led to large living collections at several major botanical gardens, but the classification of the numerous species has usually relied upon a restricted set of floral and vegetative features, and similarities among many of the forms are suspected to have evolved convergently or in parallel in many subgroups. Currently, about 80 sections (the rank between species and genus) are recognized in Begonia, but mostly on the basis of a few "key" characters used for herbarium identification. Dr. Swensen is emphasizing the acquisition of DNA sequence data from samples of several hundred species, from either nuclear or plastid gene regions, to be complemented by plastid or nuclear data from her collaborators for the same exemplar taxa. Undergraduate students will be active participants in all aspects of the research. Work will also start on morphological and anatomical characters, eventually for integration with the molecular database. Although recognized as a diverse component of tropical vegetation, the Begoniaceae are not well known, and the current classification provides little insight into their historical biogeography or into such interesting features of evolution as dioecy and associated pollination (separate staminate and pistillate plants within a species). The basal position of the single-species genus Hillebrandia in recent molecularly based phylogenies is particularly perplexing; this Hawaiian endemic may be a geologically recent introduction to the islands, or a more ancient relict. These and other biological questions will be answered when a framework phylogeny or family tree is established for the group, based on the new DNA sequence data and integrated with traditional morphological and chromosomal data.