Procheş Serban, Wilson John R U, Cowling Richard M
Department of Botany, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, South Africa.
Proc Biol Sci. 2006 May 7;273(1590):1143-8. doi: 10.1098/rspb.2005.3427.
We use a fully dated phylogenetic tree of the angiosperm families to calculate phylogenetic diversity (PD) in four South African vegetation types with distinct evolutionary histories. Since the branch length values are in this case represented by the ages of plant lineages, PD becomes the cumulative evolutionary age (CEA) of assemblages. Unsurprisingly, total CEA increases with family and with species diversity and observed values are the same as expected from random sampling of family lists. However, when random sampling is done from species lists, observed CEAs are generally lower than expected. In vegetation types which have undergone recent diversification-grassland, fynbos and Nama-karoo-co-occurring species are more closely related than expected, but in subtropical thicket the observed CEAs are well described by random sampling. The use of CEA has great potential for assessing the age of biotic assemblages, particularly as the dating of genus and species-level phylogenies become more accurate.
我们使用被子植物科的完整年代系统发育树来计算四种具有不同进化历史的南非植被类型的系统发育多样性（PD）。由于在这种情况下分支长度值由植物谱系的年龄表示，PD 就成为了组合的累积进化年龄（CEA）。不出所料，总 CEA 随科和物种多样性的增加而增加，观察到的值与从科列表的随机抽样预期的值相同。然而，当从物种列表进行随机抽样时，观察到的 CEA 通常低于预期。在最近经历了多样化的植被类型中——草原、开普植物区系和纳马夸兰-卡鲁——共存物种的亲缘关系比预期更密切，但在亚热带灌丛中，随机抽样能很好地描述观察到的 CEA。CEA 的使用在评估生物组合的年龄方面具有巨大潜力，特别是随着属和物种水平系统发育年代测定变得更加准确。
