College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China;
Research and Collections Center, Illinois State Museum, Springfield, IL 62703.
Proc Natl Acad Sci U S A. 2017 Oct 24;114(43):11452-11457. doi: 10.1073/pnas.1703985114. Epub 2017 Oct 9.
Although eastern Asia (EAS) and eastern North America (ENA) have similar climates, plant species richness in EAS greatly exceeds that in ENA. The degree to which this diversity difference reflects the ages of the floras or their rates of evolutionary diversification has not been quantified. Measures of species diversity that do not incorporate the ages of lineages disregard the evolutionary distinctiveness of species. In contrast, phylogenetic diversity integrates both the number of species and their history of evolutionary diversification. Here we compared species diversity and phylogenetic diversity in a large number of flowering plant (angiosperm) floras distributed across EAS and ENA, two regions with similar contemporary environments and broadly shared floristic history. After accounting for climate and sample area, we found both species diversity and phylogenetic diversity to be significantly higher in EAS than in ENA. When we controlled the number of species statistically, we found that phylogenetic diversity remained substantially higher in EAS than in ENA, although it tended to converge at high latitude. This pattern held independently for herbs, shrubs, and trees. The anomaly in species and phylogenetic diversity likely resulted from differences in regional processes, related in part to high climatic and topographic heterogeneity, and a strong monsoon climate, in EAS. The broad connection between tropical and temperate floras in southern Asia also might have played a role in creating the phylogenetic diversity anomaly.
虽然东亚（EAS）和北美东部（ENA）的气候相似，但东亚的植物物种丰富度大大超过北美东部。这种多样性差异在多大程度上反映了植物区系的年龄或其进化多样化的速度尚未量化。不考虑谱系年龄的物种多样性衡量标准忽略了物种的进化独特性。相比之下，系统发育多样性综合了物种的数量及其进化多样化的历史。在这里，我们比较了分布在东亚和北美东部这两个具有相似当代环境和广泛共享植物区系历史的地区的大量开花植物（被子植物）区系的物种多样性和系统发育多样性。在考虑了气候和样本面积之后，我们发现东亚的物种多样性和系统发育多样性都明显高于北美东部。当我们从统计学上控制物种数量时，我们发现东亚的系统发育多样性仍然大大高于北美东部，尽管它在高纬度地区趋于收敛。草本植物、灌木和树木的这种模式独立存在。物种和系统发育多样性的异常可能是由于区域过程的差异造成的，部分原因是高气候和地形异质性以及强烈的季风气候。南亚热带和温带植物区系之间的广泛联系也可能在创造系统发育多样性异常方面发挥了作用。
