Department of Botany, University of Reading, Whiteknights, P.O. Box 221, Reading RG6 2AS, UK.
Am J Bot. 1999 May;86(5):724-34.
A biogeographic study of Saxifraga section Saxifraga was performed based on phylogenetic analyses of ITS (internal transcribed spacer) sequences of nuclear ribosomal DNA. ITS sequences from 21 species and 31 populations were examined to identify colonization patterns for the two species of Saxifraga occurring in Macaronesia and for S. globulifera in the west Mediterranean basin. Phylogenetic analysis of the sequence data yield a single most parsimonious tree with many of the major clades well supported by bootstrap and decay values. The ITS tree provided resolution at specific and populational levels that points to two biogeographic patterns within the genus. In contrast to the molecular evidence provided by other authors for a Mediterranean origin of several Macaronesian genera of angiosperms, our results indicate that the Madeiran archipelago was colonized a single time by a species of Saxifraga originating from the Eurosiberian region. On the other hand, the molecular evidence also suggests that populations of S. globulifera from North Africa have been isolated for a long time from populations occurring in the Iberian Peninsula, and that the endemic S. reuteriana has evolved from the Iberian populations of S. globulifera. The Mediterranean Sea has probably been an effective isolating barrier for some plant groups that occur in Europe and North Africa.
基于核核糖体 DNA 的 ITS（内部转录间隔区）序列的系统发育分析，对虎耳草科虎耳草属的生物地理学进行了研究。对来自马卡罗尼西亚的两种虎耳草和西地中海盆地的虎耳草属 S. globulifera 的 21 种和 31 个种群的 ITS 序列进行了检查，以确定其殖民模式。序列数据的系统发育分析产生了一个单一的最简约树，其中许多主要分支都得到了bootstrap 和衰减值的很好支持。ITS 树在特定和种群水平上提供了分辨率，表明该属内存在两种生物地理模式。与其他作者提供的分子证据相反，这些证据表明，几个马卡罗尼西亚被子植物属起源于地中海，而我们的结果表明，马德拉群岛是由一种起源于欧亚大陆的虎耳草属物种单一殖民的。另一方面，分子证据还表明，来自北非的 S. globulifera 种群与伊比利亚半岛的种群已经长期隔离，而特有种 S. reuteriana 是从伊比利亚半岛的 S. globulifera 种群进化而来的。地中海可能是欧洲和北非一些植物群的有效隔离屏障。
