Cyriac V P, Kodandaramaiah U
IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE) and School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India.
J Evol Biol. 2018 Apr;31(4):587-598. doi: 10.1111/jeb.13248. Epub 2018 Mar 3.
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 nonfossorial snakes. Our analysis also indicates that transition rates from fossoriality to nonfossoriality in snakes are significantly lower than transition rates from nonfossoriality to fossoriality. Overall our results suggest that broad-scale ecological interactions that lead to specialization at multiple axes limit diversification.
生命之树在其分支物种丰富度上高度不对称，这通常归因于不同时间或谱系间多样化速率的差异。谱系间的差异通常与增加谱系多样化的性状相关。某些性状也可能通过增加灭绝率来阻碍多样化，这类性状被称为进化死胡同。生态特化通常被认为是一种进化死胡同。然而，最近对单轴特化的分析对此模型的支持不一。在此，我们使用最近开发的系统发育比较方法，测试穴居性（一种迫使在多个轴上特化的性状）在有鳞目动物（蜥蜴和蛇）中是否作为一种进化死胡同。我们表明，穴居性在蛇类中是进化死胡同，但在蜥蜴中并非如此。与非穴居蛇相比，穴居蛇的物种形成减少且灭绝增加。我们的分析还表明，蛇类从穴居性向非穴居性的转变速率显著低于从非穴居性向穴居性的转变速率。总体而言，我们的结果表明，导致多轴特化的广泛生态相互作用会限制多样化。
