Stern David B, Breinholt Jesse, Pedraza-Lara Carlos, López-Mejía Marilú, Owen Christopher L, Bracken-Grissom Heather, Fetzner James W, Crandall Keith A
Computational Biology Institute, The George Washington University, Ashburn, Virginia 20147.
Department of Biology, University of Florida, Gainesville, Florida.
Evolution. 2017 Oct;71(10):2522-2532. doi: 10.1111/evo.13326. Epub 2017 Sep 20.
Caves are perceived as isolated, extreme habitats with a uniquely specialized biota, which long ago led to the idea that caves are "evolutionary dead-ends." This implies 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 independently evolved 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 cave adaptation is not a "dead-end" for freshwater crayfish, which has positive implications for our understanding of biodiversity and conservation in cave habitats.
洞穴被视为孤立的极端栖息地，拥有独特的专门生物群落，这一观点由来已久，即洞穴是“进化的死胡同”。这意味着适应洞穴生活的分类群在能够多样化或过渡到更稳定的状态之前可能注定会灭绝。然而，这一假设尚未在具有多个独立进化的穴居群体的系统发育框架中得到明确检验。在这里，我们以淡水小龙虾为研究对象，淡水小龙虾在多个谱系中有数十种穴居物种，以此来检验这一假设。我们考虑谱系多样化和栖息地转变的历史模式以及当前地理分布范围大小的模式。我们发现，虽然穴居谱系的相对分布范围较小，很少重新回到地表，但它们与其他栖息地类型的谱系多样化模式惊人地相似，并且似乎能够长期维持谱系的多样性。这表明洞穴适应对淡水小龙虾来说并非“死胡同”，这对于我们理解洞穴栖息地的生物多样性和保护具有积极意义。
