Data from: Digging their own macroevolutionary grave: Fossoriality as an evolutionary dead-end in snakes

The tree of life is highly asymmetrical in its clade wise species richness and this has often been attributed to variation in diversification rates either across time or lineages. Variations across lineages are usually associated with traits that increase lineage diversification. Certain traits can also hinder diversification by increasing extinction and such traits are called evolutionary dead-ends. Ecological specialization has usually been considered as an evolutionary dead-end. However, recent analyses of specializations along single axes have provided mixed support for this model. Here, we test if fossoriality, a trait that forces specialization at multiple axes, acts as an evolutionary dead-end in squamates (lizards and snakes) using recently developed phylogenetic comparative methods. We show that fossoriality is an evolutionary dead-end in snakes but not in lizards. Fossorial snakes exhibit reduced speciation and increased extinction compared to non-fossorial snakes. Our analysis also indicates that transition rates from fossoriality to non-fossoriality in snakes are significantly lower than transition rates from non-fossoriality to fossoriality. Overall our results suggest that broad scale ecological interactions that lead to specialization at multiple axes limit diversification.生命之树在各支系的物种丰富度上呈现高度不对称性，这一现象常被归因于随时间或不同支系变化的多样化速率差异。支系间的速率差异通常与提升支系多样化速率的性状相关。部分性状则会通过提高灭绝风险阻碍多样化，这类性状被称为进化死胡同（evolutionary dead-end）。生态特化通常被视作一类进化死胡同。然而，近期针对单维度特化的分析，对该模型的支持结果却莫衷一是。本研究借助新近开发的系统发育比较方法，检验穴居性（fossoriality）——一种迫使生物在多维度上发生特化的性状——是否会在有鳞类（squamates，即蜥蜴与蛇类）中充当进化死胡同。研究结果显示，穴居性在蛇类中属于进化死胡同，但在蜥蜴类中并非如此。与非穴居蛇类相比，穴居蛇类的成种速率更低、灭绝速率更高。本研究的分析还表明，蛇类中从穴居性向非穴居性的转换速率，显著低于从非穴居性向穴居性的转换速率。综合来看，本研究结果表明，能够引发多维度特化的大规模生态相互作用，会限制物种的多样化进程。