Phylogenetic evidence from freshwater crayfishes that cave adaptation is not an evolutionary dead-end

Caves are perceived as isolated, extreme habitats with a set of uniquely specialized biota, which long ago led to the idea that caves are ‘evolutionary dead-ends.’ This suggests that cave-adapted taxa may be doomed for extinction before they can diversify or transition to a more stable state. However, this hypothesis has not been explicitly tested in a phylogenetic framework with multiple independent cave-dwelling groups. Here we use the freshwater crayfish, a group with dozens of cave-dwelling species in multiple lineages, as a system to test this hypothesis. We consider historical patterns of lineage diversification and habitat transition as well as current patterns of geographic range size. We find that while cave-dwelling lineages have small relative range sizes and rarely transition back to the surface, they exhibit remarkably similar diversification patterns to those of other habitat types and appear to be able to maintain a diversity of lineages through time. This suggests that c...洞穴向来被视为孤立且极端的生境，孕育着一系列独特特化的生物类群，这早催生了“洞穴为进化死胡同”的观点。这意味着，适应洞穴环境的类群或许在实现分化或过渡至更稳定生存状态前，就已注定走向灭绝。然而，这一假说尚未在包含多个独立穴居类群的系统发育框架（phylogenetic framework）中得到明确检验。本研究以淡水螯虾（freshwater crayfish）这一类群为研究系统——其多个支系中存在数十种穴居物种——来检验该假说。我们综合考量了支系分化与生境转换的历史模式，以及当前的地理分布范围大小格局。研究结果显示，尽管穴居支系的相对分布范围较小，且极少再转换回地表生境，但它们的分化模式与其他生境类型的类群极为相似，且似乎能够在漫长时间中维持支系多样性。这表明……