Department of Ecology and Evolution, Yale University, New Haven, CT, United States.
Evolution. 2023 Nov 2;77(11):2365-2377. doi: 10.1093/evolut/qpad143.
Geographic access to isolated ecosystems is an important catalyst of adaptive radiation. Cichlid fishes repeatedly colonized rift, crater, and volcanic lakes from surrounding rivers. We test the "lake effect" on the phenotypic rate and state across 253 cichlid species. The rate of evolution was consistently higher (~10-fold) in lakes, and consistent across different dimensions of the phenotype. Rate shifts tended to occur coincident with or immediately following river-to-lake transitions, generally resulting in 2- to 5-fold faster rates than in the founding riverine lineage. By contrast, river- and lake-dwelling cichlids exhibit considerable overlap in phenotypes, generally with less disparity in lakes, but often different evolutionary optima. Taken together, these results suggest that lake radiations rapidly expand into niches largely already represented by ancestral riverine lineages, albeit in different frequencies. Lakes may provide ecological opportunity via ecological release (e.g., from predators/competitors) but need not be coupled with access to novel ecological niches.
地理上接近孤立的生态系统是适应辐射的重要催化剂。慈鲷鱼类多次从周围的河流中殖民裂谷、火山口和火山湖。我们在 253 种慈鲷物种中测试了“湖泊效应”对表型速度和状态的影响。进化速度在湖泊中始终更高（~10 倍），并且在表型的不同维度上一致。速率变化往往与河流到湖泊的转变同时发生或紧随其后，通常导致比原始河流谱系快 2-5 倍。相比之下，河流和湖泊栖居的慈鲷在表型上有很大的重叠，通常在湖泊中差异较小，但通常有不同的进化最佳状态。总的来说，这些结果表明，湖泊辐射迅速扩展到已经由祖先河流谱系代表的生态位，尽管频率不同。湖泊可能通过生态释放（例如，免受捕食者/竞争者的影响）提供生态机会，但不一定与进入新的生态位相关联。
