Dataset_S5.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类：空间模式（例如，纬度多样性梯度）和谱系模式（例如，被子植物在植物中的优势地位）。关于谱系模式的丰富度，学术界存在争议，即此类模式是否主要由较大的谱系拥有更快的物种累积速度（物种形成减去灭绝随时间推移；多样性速率假说）或仅仅是因其历史悠久（谱系年龄假说）所解释。然而，这些研究通常比较的是同一分类等级下已命名的谱系，如门和科。这种研究设计可能对谱系年龄假说存在偏见，因为同一等级的谱系可能在年龄上比随机选择的谱系更为相似。在本研究中，我们利用大规模、时间校准的物种水平系统发育树和谱系的随机抽样，分析了生命树中谱系丰富度模式的成因。我们发现，在主要生物群体（动物、植物、真菌、细菌、古菌）中，丰富度模式与谱系年龄的相关性最为显著。尽管如此，动物和植物中存在与多样性速率的较弱关系。这些总体结果与基于已命名谱系进行的类似大规模生命研究形成了对比，后者显示谱系年龄对丰富度的影响甚微。更为广泛地，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。