The roles of phylogeny, body size and substrate use in trabecular bone variation among Philippine ‘earthworm mice’ (Rodentia: Chrotomyini)

Trabecular bone is modelled throughout an animal’s life in response to its mechanical environment, but like other skeletal anatomy, it is also subject to evolutionary influences. Yet the relative strengths of factors that affect trabecular bone architecture are little studied. We investigated these influences across the Philippine endemic murine rodent clade Chrotomyini. These mammals have robustly established phylogenetic relationships, exhibit a range of well-documented substrate-use types, and have a body size range spanning several hundred grammes, making them ideal for a tractable study of extrinsic and intrinsic influences on trabecular bone morphology.
We found slight differences in vertebral trabecular bone among different substrate-use categories, with more divergent characteristics in more ecologically specialized taxa. This suggests that the mechanical environment must be relatively extreme to affect trabecular bone morphology in small mammals. We also recovered allometric pa..., Scans of murine vertebral columns (museum specimens sourced from the Field Museum of Natural History) were collected using a GE phoenix v|tome|x µCT scanner. Spherical VOIs were chosen and segmented in ORS Dragonfly 2021. Trabecular bone morphological data were collected from medullary cavity VOIs using Dragonfly and BoneJ. See publication Methods section for additional details.,

骨小梁（trabecular bone）会在动物的一生中根据其所处的机械环境进行重塑；与其他骨骼解剖结构一样，它同样受到进化因素的调控。然而，目前针对影响骨小梁架构的各类因素的相对影响力，相关研究仍较为匮乏。我们以菲律宾特有啮齿类鼠科Chrotomyini族为研究类群，探究上述两类因素的相对影响强度。该类群哺乳动物的系统发育关系已得到充分阐明，其基质利用模式多样且有详实记录，体重跨度达数百克，因此是开展骨小梁形态受外在与内在因素影响研究的理想实验对象。研究发现，不同基质利用模式类群的椎体骨小梁存在细微差异，生态特化程度更高的类群其骨小梁特征分化更为显著。这表明，若要对小型哺乳动物的骨小梁形态产生显著影响，机械环境需达到相对极端的水平。我们还发现了异速生长相关的模式（原文此处存在截断），小鼠椎体的扫描成像（标本源自菲尔德自然历史博物馆馆藏）采用GE phoenix v|tome|x µCT扫描仪完成。研究人员在ORS Dragonfly 2021软件中选取球形感兴趣区（VOI, Volume of Interest）并进行分割；随后利用Dragonfly与BoneJ软件，从髓腔感兴趣区中采集骨小梁形态学数据。更多细节请参阅已发表论文的方法部分。