Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, Wisconsin 53706 USA;
Am J Bot. 2005 Sep;92(9):1520-34. doi: 10.3732/ajb.92.9.1520.
Parsimony, likelihood, and Bayesian analyses of nuclear ITS and plastid trnL-F DNA sequence data are presented for the giant genus Croton (Euphorbiaceae s.s.) and related taxa. Sampling comprises 88 taxa, including 78 of the estimated 1223 species and 29 of the 40 sections previously recognized of Croton. It also includes the satellite genus Moacroton and genera formerly placed in tribe Crotoneae. Croton and all sampled segregate genera form a monophyletic group sister to Brasiliocroton, with the exception of Croton sect. Astraea, which is reinstated to the genus Astraea. A small clade including Moacroton, Croton alabamensis, and C. olivaceus is sister to all other Croton species sampled. The remaining Croton species fall into three major clades. One of these is entirely New World, corresponding to sections Cyclostigma, Cascarilla, and Velamea sensu Webster. The second is entirely Old World and is sister to a third, also entirely New World clade, which is composed of at least 13 of Webster's sections of Croton. This study establishes a phylogenetic framework for future studies in the hyper-diverse genus Croton, indicates a New World origin for the genus, and will soon be used to evaluate wood anatomical, cytological, and morphological data in the Crotoneae tribe.
对巨型属 Croton（Euphorbiaceae s.s.）及其相关类群的核 ITS 和质体 trnL-F DNA 序列数据进行简约法、似然法和贝叶斯分析。采样包括 88 个分类群，包括估计的 1223 种中的 78 种和 Croton 先前识别的 40 个节中的 29 种。它还包括卫星属 Moacroton 和以前归入 Crotoneae 族的属。Croton 和所有采样的分离属形成一个单系群，与 Brasiliocroton 为姐妹群，除了 Croton 节 Astraea，它被恢复为 Astraea 属。一个包括 Moacroton、Croton alabamensis 和 C. olivaceus 的小分支与所有其他采样的 Croton 物种为姐妹群。其余的 Croton 物种分为三个主要分支。其中一个完全是新世界的，对应于 Webste 定义的 Cyclostigma、Cascarilla 和 Velamea 节。第二个完全是旧世界的，与第三个也是完全新世界的分支为姐妹群，该分支至少由 Webster 定义的 Croton 的 13 个节组成。本研究为未来在 Croton 这一高度多样化的属中进行的研究建立了一个系统发育框架，表明该属起源于新世界，并将很快用于评估 Crotoneae 族中的木材解剖学、细胞学和形态学数据。
