Phylogeny, macroevolutionary trends and historical biogeography of sloths: insights from a Bayesian morphological clock analysis

Sloths, like other xenarthrans, are an extremely interesting group of mammals that, after a long history of evolution and diversification in South America, became established on islands in the Caribbean and later reached North America during the Great American Biotic Interchange. In all three regions they were part of the impressive Pleistocene megafauna. Most taxa became extinct and only two small, distantly related tree-dwelling genera survived. Here we incorporate several recently described genera of sloths into an assembled morphological data supermatrix and apply Bayesian inference, using phylogenetic and morphological clock methods, to 64 sloth genera. Thus, we investigate the evolution of the group in terms of the timing of divergence of different lineages and their diversity, morphological disparity and biogeographical history. The phylogeny obtained supports the existence of the commonly recognized clades for the group. Our results provide divergence time estimates for the majo...

树懒与其他异关节总目（Xenarthra）类群一样，是一类极具科研价值的哺乳动物。它们在南美洲经历了漫长的演化与分化历程后，于加勒比海群岛定居，随后借助北美生物大交换（Great American Biotic Interchange）迁至北美洲。在上述三个区域中，树懒均属于更新世（Pleistocene）极具代表性的巨型动物群（megafauna）。绝大多数树懒分类群（taxa）已走向灭绝，仅存两个体型小巧、亲缘关系疏远的树栖属类群。本研究将多个近年新定名的树懒属类群整合至组装完成的形态学数据超级矩阵中，并采用系统发育与形态钟分析方法，针对64个树懒属类群开展贝叶斯推断（Bayesian inference）分析。借此，我们从不同支系的分化时间、类群多样性、形态分异度以及生物地理历史等维度，探究树懒类群的演化历程。所得系统发育树支持该类群目前公认的各演化支（clade）的存在。本研究结果为主要的……（majo...）