Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
New Phytol. 2018 Jul;219(1):436-448. doi: 10.1111/nph.15144. Epub 2018 Apr 17.
What causes the disparity in biodiversity among regions is a fundamental question in biogeography, ecology, and evolutionary biology. Evolutionary and biogeographic processes (speciation, extinction, dispersal) directly determine species richness patterns, and can be studied using integrative phylogenetic approaches. However, the strikingly high richness of East Asia relative to other Northern Hemisphere regions remains poorly understood from this perspective. Here, for the first time, we test two general hypotheses (older colonization time, faster diversification rate) to explain this pattern, using the plant tribe Lysimachieae (Primulaceae) as a model system. We generated a new time-calibrated phylogeny for Lysimachieae (13 genes, 126 species), to estimate colonization times and diversification rates for each region and to test the relative importance of these two factors for explaining regional richness patterns. We find that neither time nor diversification rates alone explain richness patterns among regions in Lysimachieae. Instead, a new index that combines both factors explains global richness patterns in the group and their high East Asian biodiversity. Based on our results from Lysimachieae, we suggest that the high richness of plants in East Asia may be explained by a combination of older colonization times and faster diversification rates in this region.
造成地区间生物多样性差异的原因是生物地理学、生态学和进化生物学中的一个基本问题。进化和生物地理过程（物种形成、灭绝、扩散）直接决定了物种丰富度模式，可以通过综合系统发育方法进行研究。然而，从这个角度来看，东亚与其他北半球地区相比具有极高的丰富度，这一点仍未得到很好的理解。在这里，我们首次使用报春花科露珠草族（Lysimachieae）作为模型系统，检验了两个解释该模式的一般假说（较老的殖民时间、较快的多样化速度）。我们为露珠草族生成了一个新的时间校准系统发育树（13 个基因，126 个物种），以估计每个地区的殖民时间和多样化速度，并检验这两个因素对解释地区丰富度模式的相对重要性。我们发现，无论是时间还是多样化速度都不能单独解释露珠草族地区间的丰富度模式。相反，一个结合了这两个因素的新指数可以解释该组的全球丰富度模式及其在东亚的高生物多样性。基于我们对露珠草族的研究结果，我们认为东亚植物的高丰富度可以用该地区较老的殖民时间和较快的多样化速度来解释。
