Bone cortical compactness in ‘tree sloths’ reflects convergent evolution
Bone cortical compactness in ‘tree sloths’ reflects convergent evolution
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“树懒”的骨皮质致密性反映了趋同进化
DOI：
10.1111/joa.12873
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发表时间：
2018
影响因子：
2.4
通讯作者：
John A.
中科院分区：
文献类型：
--
作者：
Montañez-Rivera;Nyakatura;John A.
骨重建是调节骨微结构的主要过程之一，包括骨吸收，继而在同一位置沉积次级骨。不同类群的重塑强度不同，但在成熟陆地哺乳动物的长骨中，普遍存在着一种特有的致密皮质。先前的一项分析发现，少数树懒(Bradypus和Choloepus)标本的皮质骨被严重重塑，并以大量未成熟的次生骨为特征，这表明这些动物直到个体发育后期都在以高速度重塑自己的骨骼。这项研究的目的是测试这种重塑是否普遍存在于“树懒”中，通过对异氟烃中的肱骨皮质致密性(CC)进行定量分析。对10个异种的26个标本(包括灭绝物种和现存物种的标本)的横断面的研究结果表明，‘树懒’的CC值显著低于其他采样的异种标本。树懒两属的CC值无显著差异。我们的结果与这样的假设是一致的，即树懒的皮质骨通常经历着强烈而平衡的重塑，这种重塑一直保持到个体发育的后期(可能是整个)。从Xenarthran的系统发育来看，低CC值代表了长期分离的树懒谱系之间的另一种趋同。尽管与这一特征相关的确切的结构和/或功能需求到目前为止还不清楚，但这里提出了几个假设，包括与它们相对较低的新陈代谢以及由两个树懒属独立获得的悬挂姿势和运动对骨骼施加的机械需求之间的关系。
Bone remodeling, one of the main processes that regulate bone microstructure, consists of bone resorption followed by the deposition of secondary bone at the same location. Remodeling intensity varies among taxa, but a characteristically compact cortex is ubiquitous in the long bones of mature terrestrial mammals. A previous analysis found that cortical bone in a few ‘tree sloth’ (BradypusandCholoepus) specimens is heavily remodeled and characterized by numerous immature secondary osteons, suggesting that these animals were remodeling their bones at high rate until late in their ontogeny. This study aims at testing if this remodeling is generally present in ‘tree sloths’, using a quantitative analysis of the humeral cortical compactness (CC) among xenarthrans. The results of the investigation of humeral diaphyseal cross‐sections of 26 specimens belonging to 10 xenarthran species including specimens from both extinct and extant species indicate that in ‘tree sloths’ theCCis significantly lower than in the other sampled xenarthrans. No significant difference was found between theCCof the two genera of ‘tree sloths’. Our results are consistent with the hypothesis that the cortical bone of ‘tree sloths’ in general undergoes intense and balanced remodeling that is maintained until late (possibly throughout) in their ontogeny. In the light of xenarthran phylogeny, lowCCrepresents another convergence between the long‐separated ‘tree sloth’ lineages. Although the exact structural and/or functional demands that are associated with this trait are hitherto unknown, several hypotheses are suggested here, including a relationship to their relatively low metabolism and to the mechanical demands imposed upon the bones by the suspensory posture and locomotion, which was independently acquired by the two genera of ‘tree sloths’.
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DOI：
10.18563/journal.m3.64
发表时间：
2018
期刊：
Proceedings of the Royal Society of London. Series B: Biological Sciences
影响因子：
--
作者：
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通讯作者：
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DOI：
10.1098/rspb.2001.1702
发表时间：
2001-08-07
影响因子：
4.7
作者：
Delsuc, F;Catzeflis, FM;Douzery, EJP
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影响因子：
3.5
作者：
C. Muizon;H. Gregory McDonald;R. Salas;M. Urbina
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影响因子：
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作者：
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通讯作者：
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