A Phylogenetic Monograph of New World Vigna sensu lato (Fabaceae)

[007520]植物学家马特·拉文和诺姆·维登与墨西哥合作者阿方索·德尔加多·萨里纳斯正在研究豆科植物的分类学和进化，这些豆科植物传统上被认为是大属的豆科植物，其东半球成员包括红豆和绿豆。它们的初步分子（DNA序列数据）和形态学研究表明，作为豆科植物的新大陆物种实际上与其他新大陆豆科植物（如Dolichopsis、Mysanthus、Phaseolus和Strophostyles）的关系比与旧大陆豆科植物的关系更密切。本研究拟对维格纳属及其他近缘属140余种的遗传和形态变异进行分析，重点分析核和叶绿体基因的DNA序列数据，并结合植物标本馆标本和野外采集的形态学特征。这项研究的一个成果将是一个基于进化亲缘关系的分类学，植物育种者将能够使用它作为最有效地选择在涉及杂交的实验中使用的物种或种族的指南。目前，这对植物育种者来说是不可用的。遗传分析也具有重要的生物地理学意义。再一次，初步证据表明，所有新世界的物种形成了一个基因上独特的群体，与另一个以非洲和亚洲为中心的基因上独特的群体关系最为密切。水上迁徙可能是这种分裂的山脉模式的一种解释，但也有可能是一个曾经广泛分布的古老山脉被灭绝事件或非洲和美洲之间的大陆漂移所分裂。研究人员希望从他们从研究物种中积累的DNA数据中识别出“遗传足迹”，这可能表明哪些物种是各自大陆上的古代物种（即追溯到大约4000万年前），哪些物种是最近从另一个大陆来的。

0075202Lavin and Weeden Botanists Matt Lavin and Norm Weeden, with Mexican collaborator Alfonso Delgado-Salinas, are studying the taxonomy and evolution of the legumes traditionally treated in the large genus Vigna, the Old World members of which include azuki bean and mungbean. Their preliminary molecular (DNA sequence data) and morphological studies show that New World species treated as Vigna in fact are more closely related to other New World legume genera like Dolichopsis, Mysanthus, Phaseolus, and Strophostyles than to the Old World Vigna. The study proposes to analyze the genetic and morphological variation of 140 or so species in Vigna and these other closely related genera, emphasizing in particular DNA sequence data from nuclear and chloroplast genes and adding morphological characters studied from herbarium specimens and field collections. One product of this study will be a taxonomy based on evolutionary relatedness, which plant breeders will be able to use as a guide for most efficiently selecting which species or races to use in experiments involving hybridization. Currently, this is not available to plant breeders for this group of plants. Genetic analysis of the species of Vigna also has biogeographic importance. Again, preliminary evidence reveals that all of the New World species form a genetically distinctive group that is most closely related to another genetically singular group centered in Africa and Asia. Over-water migration is one possible explanation for this disjunct pattern of split ranges, but it is also possible that a once-widespread, ancient range has been split by extinction events or by continental drift between Africa and the Americas. The investigators hope to identify "genetic footprints" in the DNA data they accumulate from the studied species, that may indicate which species are ancient (i.e., dating back to about 40 million years) on their respective continents, and which species are recent arrivals from another continent.