Linder H P, Hardy C R
Institute of Systematic Botany, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
Philos Trans R Soc Lond B Biol Sci. 2004 Oct 29;359(1450):1623-32. doi: 10.1098/rstb.2004.1534.
The Cape Floristic Region ('fynbos biome') has very high levels of plant species diversity and endemism. Much of this diversity is concentrated in a relatively small number of clades centered in the region (Cape clades), and these form a vegetation called 'fynbos'. The general explanation for the origin of this diversity is that much of it evolved in the Pliocene and Late Miocene in response to progressive aridification. We present a phylogenetic analysis of an almost complete species sample of the largest clade of Restionaceae, the third largest Cape clade. This indicates that the radiation of the Restionaceae started between 20 and 42 Myr ago, and since then there were no, or at most gradual, changes in the speciation rate in this clade. For seven other clades, the estimated starting dates for their radiation ranges from 7 to 20 Myr ago. Combining the radiation patterns for these clades shows that ca. 15% of the modern species evolved during the Pleistocene, and almost 40% since the beginning of the Pliocene. We suggest that these clades might have radiated in response to the fynbos vegetation increasing its extent in the Cape as a result of climatic change.
开普植物区（“开普植物群系生物群落”）拥有极高的植物物种多样性和特有性。这种多样性的很大一部分集中在该地区以一些相对较少的分支为中心（开普分支），这些分支形成了一种名为“开普植物群系”的植被。对这种多样性起源的一般解释是，它的大部分是在晚上新世和上新世为应对逐渐干旱化而进化形成的。我们对帚灯草科最大分支（开普第三大分支）几乎完整的物种样本进行了系统发育分析。这表明帚灯草科的辐射始于2000万至4200万年前，从那时起，该分支的物种形成速率没有变化，或者最多只有逐渐的变化。对于其他七个分支，其辐射的估计起始日期为700万至2000万年前。综合这些分支的辐射模式表明，约15%的现代物种在更新世期间进化而来，自上新世开始以来几乎40%的物种进化而来。我们认为，这些分支可能是由于气候变化导致开普植物群系植被范围扩大而辐射进化的。
