Data from: Fully-sampled phylogenies of squamates reveal evolutionary patterns in threat status

Macroevolutionary rates of diversification and anthropogenic extinction risk differ vastly throughout the Tree of Life. This results in a highly heterogeneous distribution of Evolutionary distinctiveness (ED) and threat status among species. We examine the phylogenetic distribution of ED and threat status for squamates (amphisbaenians, lizards, and snakes) using fully-sampled phylogenies containing 9574 species and expert-based estimates of threat status for ~ 4000 species. We ask whether threatened species are more closely related than would be expected by chance and whether high-risk species represent a disproportionate amount of total evolutionary history. We found currently-assessed threat status to be phylogenetically clustered at broad level in Squamata, suggesting it is critical to assess extinction risks for close relatives of threatened lineages. Our findings show no association between threat status and ED, suggesting that future extinctions may not result in a disproportionate loss of evolutionary history. Lizards in degraded tropical regions (e.g., Madagascar, India, Australia, and the West Indies) seem to be at particular risk. A low number of threatened high-ED species in areas like the Amazon, Borneo, and Papua New Guinea may be due to a dearth of adequate risk assessments. It seems we have not yet reached a tipping point of extinction risk affecting a majority of species; 63% of the assessed species are not threatened and 56% are Least Concern. Nonetheless, our results show that immediate efforts should focus on geckos, iguanas, and chameleons, representing 67% of high-ED threatened species and 57% of Unassessed high-ED lineages.

生命之树（Tree of Life）各分支的宏观演化分化速率与人类活动引发的灭绝风险差异悬殊。这使得各物种间的进化独特性（Evolutionary distinctiveness, ED）与濒危等级分布呈现高度异质性。本研究依托涵盖9574个物种的全面采样系统发育树，以及约4000个物种的专家评估濒危等级数据，针对鳞龙类（squamates，包括蚓蜥类、蜥蜴类与蛇类）的进化独特性与濒危等级的系统发育分布格局展开分析。本研究旨在解答两个科学问题：受威胁物种是否较随机预期更为近亲，以及高风险物种是否占据了不成比例的总演化历史份额。研究结果显示，当前已完成评估的濒危等级在鳞龙类中呈现宏观尺度的系统发育聚集特征，这表明对受威胁类群的近缘物种开展灭绝风险评估工作至关重要。本研究未发现濒危等级与进化独特性存在显著关联，这暗示未来的物种灭绝或不会导致演化历史出现不成比例的丢失。热带退化区域的蜥蜴类（如马达加斯加、印度、澳大利亚与西印度群岛）似乎面临尤其高的灭绝风险。亚马逊、婆罗洲与巴布亚新几内亚等区域的受威胁高进化独特性物种数量偏少，这可能缘于当前缺乏充分的灭绝风险评估工作。目前我们尚未抵达影响多数物种的灭绝风险临界点：已评估的物种中63%未受威胁，56%为无危（Least Concern）等级。尽管如此，本研究结果表明亟需即刻针对壁虎类、鬣蜥类与变色龙类开展保护行动——这三类群占据了67%的受威胁高进化独特性物种，以及57%的未评估高进化独特性类群。