Ecomorphological convergence in Eleutherodactylus frogs: a case of replicate radiations in the Caribbean

Replicate radiations, the repeated multiplication of species associated with ecological divergence, have attracted much attention and generated as much debate. Due to the few well‐studied cases, it remains unclear whether replicate radiations are an exceptional result of evolution or a relatively common example of the power of adaptation by natural selection. We examined the case of Eleutherodactylus frogs, which radiated in the Caribbean islands resulting in more than 160 species that occupy very diverse habitats. A time‐calibrated phylogeny revealed that these frogs independently diversified on all larger islands producing species that occupy a broad range of microhabitats in different islands. Using phylogenetic comparative methods, we found an association between morphological traits and particular microhabitats, and for most microhabitats detected significant morphological convergence. Our results indicate Caribbean Eleutherodactylus are a novel example of replicate radiations, and highlight the predictability of evolutionary processes, as similar ecological opportunities can lead to similar outcomes.

重复辐射演化（replicate radiations）指与生态分化相关的物种反复增殖现象，长期以来备受学界关注，同时也引发了诸多争议。由于目前得到深入研究的案例寥寥无几，学界至今仍未明确：重复辐射演化究竟是演化进程中的特例，还是自然选择适应性作用的一种较为普遍的体现。本研究以卵齿蟾属（Eleutherodactylus）蛙类为研究对象，该类群在加勒比群岛发生辐射演化，衍生出160余种栖息于多样生境的物种。通过时间校准的系统发育树分析显示，这些蛙类在所有较大的加勒比岛屿上独立发生分化，不同岛屿上的物种分别占据了广泛的微生境类型。本研究运用系统发育比较分析方法（phylogenetic comparative methods），发现形态性状与特定微生境之间存在显著关联；且针对多数微生境类型，均检测到了显著的形态趋同现象。本研究结果表明，加勒比地区的卵齿蟾属蛙类是重复辐射演化的一个全新案例，同时也印证了演化进程的可预测性——相似的生态机遇可催生相似的演化结果。