Law Chris J, Linden Tate J, Flynn John J
Burke Museum and Department of Biology, University of Washington, Seattle, WA, USA.
Division of Paleontology, American Museum of Natural History, New York, NY, USA.
R Soc Open Sci. 2024 Oct 23;11(10):240538. doi: 10.1098/rsos.240538. eCollection 2024 Oct.
Madagascar is one of the world's foremost biodiversity hotspots with more than 90% of its species endemic to the island. Malagasy carnivorans are one of only four extant terrestrial mammalian clades endemic to Madagascar. Although there are only eight extant species, these carnivorans exhibit remarkable phenotypic and ecological diversity that is often hypothesized to have diversified through an adaptive radiation. Here, we investigated the evolution of skull diversity in Malagasy carnivorans and tested if they exhibited characteristics of convergence and an adaptive radiation. We found that their skull disparity exceeds that of any other feliform family, as their skulls vary widely and strikingly capture a large amount of the morphological variation found across all feliforms. We also found evidence of shared adaptive zones in cranial shape between euplerid subclades and felids, herpestids and viverrids. Lastly, contrary to predictions of adaptive radiation, we found that Malagasy carnivorans do not exhibit rapid lineage diversification and only marginally faster rates of mandibular shape evolution and to a lesser extent cranial shape evolution, compared to other feliforms. These results reveal that exceptional diversification rates are not necessary to generate the striking phenotypic diversity that evolved in carnivorans after their dispersal to and isolation on Madagascar.
马达加斯加是世界上最重要的生物多样性热点地区之一，其90%以上的物种为该岛特有。马达加斯加食肉动物是马达加斯加仅有的四个现存陆地哺乳动物分支之一。虽然现存只有八个物种，但这些食肉动物表现出显著的表型和生态多样性，人们常常假设它们是通过适应性辐射而多样化的。在这里，我们研究了马达加斯加食肉动物头骨多样性的进化，并测试它们是否表现出趋同和适应性辐射的特征。我们发现，它们的头骨差异超过了任何其他猫型总科动物，因为它们的头骨差异很大，显著涵盖了所有猫型总科动物中发现的大量形态变异。我们还发现了鼬形亚科与猫科、獴科和灵猫科在颅骨形状上共享适应区的证据。最后，与适应性辐射的预测相反，我们发现马达加斯加食肉动物没有表现出快速的谱系多样化，与其他猫型总科动物相比，它们的下颌形状进化速度仅略快，颅骨形状进化速度则较慢。这些结果表明，在食肉动物扩散到马达加斯加并在那里隔离后，产生其显著的表型多样性并不一定需要异常高的多样化速率。
