Dataset_S1.xlsx from The causes of species richness patterns among clades

Two major types of species richness patterns are spatial (e.g. the latitudinal diversity gradient) and clade-based (e.g. the dominance of angiosperms among plants). Studies have debated whether clade-based richness patterns are explained primarily by larger clades having faster rates of species accumulation (speciation minus extinction over time; diversification-rate hypothesis) or by simply being older (clade-age hypothesis). However, these studies typically compared named clades of the same taxonomic rank, such as phyla and families. This study design is potentially biased against the clade-age hypothesis, since clades of the same rank may be more similar in age than randomly selected clades. Here, we analyse the causes of clade-based richness patterns across the tree of life using a large-scale, time-calibrated, species-level phylogeny and random sampling of clades. We find that within major groups of organisms (animals, plants, fungi, bacteria, archaeans), richness patterns are most strongly related to clade age. Nevertheless, weaker relationships with diversification rates are present in animals and plants. These overall results contrast with similar large-scale analyses across life based on named clades, which showed little effect of clade age on richness. More broadly, these results help support the overall importance of time for explaining diverse types of species richness patterns.

物种丰富度模式主要分为两大类：空间模式（例如，纬度多样性梯度）和系统发育分支模式（例如，被子植物在植物中的优势地位）。关于基于系统发育分支的丰富度模式，研究者们争论其是否主要由较大的系统发育分支拥有更快的物种累积速率（物种分化减去灭绝随时间推移；多样性速率假说）或仅仅是由于它们更为古老（系统发育分支年龄假说）所解释。然而，这些研究通常比较的是同一分类等级上的命名系统发育分支，如门和科。这种研究设计可能对系统发育分支年龄假说存在偏见，因为同一等级的系统发育分支可能在年龄上比随机选择的分支更为相似。在本研究中，我们采用大规模、时间校准的物种水平系统发育树和系统发育分支的随机抽样，分析了系统发育分支丰富度模式在生物树上的成因。我们发现，在生物的主要群体（动物、植物、真菌、细菌、古菌）中，丰富度模式与系统发育分支年龄的关系最为密切。尽管在动物和植物中，与多样性速率的关系较弱。这些总体结果与基于命名系统发育分支的类似大规模生命分析形成对比，后者显示系统发育分支年龄对丰富度的影响微乎其微。更广泛地，这些结果有助于支持时间在解释多种类型的物种丰富度模式中的整体重要性。