Phylogeny and Evolution of Caesalpinioid Legumes

豆科（或豆科）是开花植物的第三大科，也是经济上第二重要的科。豆科植物从巨大的雨林树木到沙漠栖息地的小型一年生草本植物。在传统上公认的三个亚科，沙蝇亚科，含羞草亚科和凤蝶亚科中，沙蝇亚科是最不为人所知的，因为它主要局限于热带栖息地。因此，类凯撒豆科植物之间的进化关系鲜为人知，对特定属的认识经常存在争议。Herendeen博士和他在加拿大和英国的同事们之前的工作已经为Caesalpinioideae开发了一个一般的系统发育框架，这将用于进一步的形态学、分类学和系统发育研究。目前的形态学和分子数据表明，一些caesalpinoids谱系比Mimosoideae或Papilionoideae具有更多的基部位置。因此，基于进化关系的科分类系统不会将caesalpinoids视为单一的自然单位，而是将其视为几个早期分支谱系。豆科植物有多少个不同的谱系，相对于拟虫科和拟蝶科，它们应该在什么水平上被认识，豆科植物属之间的关系是什么，我们可以从形态进化的模式中看出什么？这些问题构成了本研究的核心。本研究的主要目的是根据形态学和DNA序列数据的分析，建立一个包括所有约160属的豆科植物的分类。为实现这一目标，将在马达加斯加、南美洲和东南亚开展实地工作，以获取尽可能多的缺失属的资料。研究人员还将研究植物标本馆的收藏，并准备解剖样本，以对分子数据集中所有物种的形态特征进行评分。他们将利用系统发育的结果为所有的凯撒科豆科植物提供一个修订的分类和亚科、部落和属的鉴定钥匙。凭借强大的系统发育和基于标本的形态数据集，他们将能够探索系统发育与形态进化模式的含义。此外，各种各样的豆科植物化石的数据将与结果相结合。这些化石可用于记录进化枝的最低年龄，并可作为生物地理学研究的历史数据点。此外，分子钟技术将用于估计进化枝的年龄。本研究产生的数据将使豆科植物成为一个理想的类群，用于实验估算进化枝年龄、评估分类多样化率和分子进化率的新方法。

The Leguminosae (or Fabaceae - the legume or bean family) is the third largest family of flowering plants, and the second most important family economically. Legumes range from giant rain forest trees to tiny herbaceous annuals of desert habitats. Of the three traditionally recognized subfamilies, Caesalpinioideae, Mimosoideae, and Papilionoideae, the Caesalpinioideae is the most poorly known because it is largely confined to tropical habitats. As a consequence, evolutionary relationships among caesalpinioid legumes are poorly known and the recognition of particular genera is often in dispute. Previous work by Dr. Herendeen and his colleagues in Canada and England has developed a general phylogenetic framework for Caesalpinioideae, which will be used to further research on morphology, taxonomy, and phylogeny. Current morphological and molecular data show that several caesalpinioid lineages have more basal positions than either the Mimosoideae or Papilionoideae. Thus a classification system for the family based on evolutionary relationships would not recognize the caesalpinioids as a single natural unit but as several early-branching lineages. How many distinct lineages of caesalpinioid legumes are there, at what level should they be recognized relative to mimosoids and papilionoids, what are the relationships among caesalpinioid genera, and what can we discern about patterns of morphological evolution? These questions form the core of the study. The primary goal of this research is to produce a classification that includes all ca. 160 genera of caesalpinioid legumes based on analyses of data from morphology and DNA sequence data. To achieve this, field work will be conducted in Madagascar, South America, and SE Asia to obtain material of as many of the missing genera as possible. The investigators will also study collections in herbaria and prepare anatomical samples to score morphological characters for all species included in the molecular data set. They will use the phylogenetic results to produce a revised classification and identification key to subfamilies, tribes, and genera for all caesalpinioid legumes. With a robust phylogeny and a specimen-based morphological data set, they will be able to explore the implications of the phylogeny with respect to patterns of morphological evolution. In addition, data on a diverse array of fossil legumes will be integrated with the results. The fossils may be used in documenting minimum ages of clades and as historical data points for biogeographic studies. In addition, molecular clock techniques will be used to estimate ages of clades. The data generated in this study will make the Leguminosae an ideal group in which to experiment with new methods in estimating ages of clades and assessing rates of taxonomic diversification and molecular evolution.