Convergent evolution is a major topic in evolutionary biology. Low bone cortical compactness (CC, a measure of porosity of cortical bone) in the extant genera of 'tree sloths', has been linked to their convergent slow arboreal ecology. This proposed relationship of low CC with a slow arboreal lifestyle suggests potential convergent evolution of this trait in other slow arboreal mammals. Femoral and humeral CC were analysed in 'tree sloths', lorisids, koala, and extinct paleopropithecids and Megaladapis, in comparison to closely related but ecologically distinct taxa, in a phylogenetic framework. Low CC in 'tree sloths' is unparalleled by any analysed clade and the high CC in extinct sloths suggests the recent convergence of low CC in 'tree sloths'. A tendency for low CC was found in Palaeopropithecus and Megaladapis. However, lorisids and the koala yielded unexpected CC patterns, preventing the recognition of a straightforward convergence of low CC in slow arboreal mammals. This study uncovers a complex relationship between CC and convergent evolution of slow arboreality, highlighting the multifactorial specificity of bone microstructure. This article is protected by copyright. All rights reserved.

中文翻译：

---

慢树栖哺乳动物骨皮质致密性的演变

趋同进化是进化生物学的一个主要课题。现存“树懒”属中的低骨皮质紧密度（CC，皮质骨孔隙度的量度）与它们收敛的缓慢树栖生态有关。这种低 CC 与缓慢的树栖生活方式之间的关系表明，这种特性在其他缓慢的树栖哺乳动物中存在潜在的趋同进化。在系统发育框架中，与密切相关但生态上不同的分类群相比，在“树懒”、lorisids、考拉和已灭绝的古生物和 Megaladapis 中分析了股骨和肱骨 CC。“树懒”中的低 CC 是任何分析进化枝都无法比拟的，而且已灭绝树懒中的高 CC 表明最近“树懒”中的低 CC 趋同。在 Palaeopropithecus 和 Megaladapis 中发现了低 CC 的趋势。然而，lorisids 和考拉产生了意想不到的 CC 模式，阻止了在慢速树栖哺乳动物中识别低 CC 的直接收敛。这项研究揭示了 CC 与缓慢树栖的趋同进化之间的复杂关系，突出了骨骼微结构的多因素特异性。本文受版权保护。版权所有。