Am Nat. 2019 Apr;193(4):514-529. doi: 10.1086/702253. Epub 2019 Feb 20.
Most groups of organisms occur in multiple regions and have different numbers of species in different regions. These richness patterns are directly explained by speciation, extinction, and dispersal. Thus, regional richness patterns may be explained by differences in when regions were colonized (more time for speciation in regions colonized earlier), differences in how often they were colonized, or differences in diversification rates (speciation minus extinction) among regions (with diversification rates potentially influenced by area, climate, and/or many other variables). Few studies have tested all three factors, and most that did examined them only in individual clades. Here, we analyze a diverse set of 15 clades of plants and animals to test the causes of regional species richness patterns within clades. We find that time was the sole variable significantly explaining richness patterns in the best-fitting models for most clades (10/15), whereas time combined with other factors explained richness in all others. Time was the most important factor explaining richness in 13 of 15 clades, and it explained 72% of the variance in species richness among regions across all 15 clades (on average). Surprisingly, time was increasingly important in older and larger clades. In contrast, the area of the regions was relatively unimportant for explaining these regional richness patterns. A systematic review yielded 15 other relevant studies, which also overwhelmingly supported time over diversification rates (13 to 1, with one study supporting both diversification rates and time). Overall, our results suggest that colonization time is a major factor explaining regional-scale richness patterns within clades (e.g., families).
大多数生物群体存在于多个区域，在不同的区域具有不同数量的物种。这些丰富度模式直接由物种形成、灭绝和扩散来解释。因此，区域丰富度模式可以通过以下因素来解释：不同地区的殖民时间（较早殖民的地区有更多的物种形成时间）、殖民频率的差异，或各地区（潜在地受到面积、气候和/或许多其他变量的影响）的多样化率（物种形成减去灭绝）的差异。很少有研究测试了所有这三个因素，而且大多数研究仅在个别分支中检验了它们。在这里，我们分析了一组多样化的植物和动物 15 个分支，以检验分支内区域物种丰富度模式的原因。我们发现，对于大多数分支（10/15），时间是唯一显著解释丰富度模式的变量，而时间与其他因素结合解释了其他所有分支的丰富度。时间是 15 个分支中的 13 个分支中解释丰富度的最重要因素，它解释了 15 个分支中所有地区之间物种丰富度的 72%的差异（平均而言）。令人惊讶的是，时间在较老和较大的分支中变得越来越重要。相比之下，地区的面积对于解释这些区域丰富度模式相对不重要。系统评价产生了 15 项其他相关研究，这些研究也压倒性地支持时间而不是多样化率（13 比 1，一项研究同时支持多样化率和时间）。总的来说，我们的结果表明，殖民时间是解释分支内（例如，家族）区域尺度丰富度模式的主要因素。
