PDF(Pubmed)
Abstract：
The increased limb bone density documented previously for aquatic tetrapods has been proposed to be an adaptation to overcome buoyancy during swimming and diving. It can be achieved by increasing the amount of bone deposition or by reducing the amount of bone resorption, leading to cortical thickening, loss of medullary cavity, and compaction of trabecular bone. The present study examined the effects of locomotor habit, body size, and phylogeny on the densitometric, cross-sectional, and biomechanical traits of femoral diaphysis and neck in terrestrial, semiaquatic, and aquatic carnivores, and in terrestrial and semiaquatic rodents (12 species) by using peripheral quantitative computed tomography, three-point bending, and femoral neck loading tests. Groupwise differences were analyzed with the univariate generalized linear model and the multivariate linear discriminant analysis supplemented with hierarchical clustering. While none of the individual features could separate the lifestyles or species adequately, the combinations of multiple features produced very good or excellent classifications and clusterings. In the phocid seals, the aquatic niche allowed for lower femoral bone mineral densities than expected based on the body mass alone. The semiaquatic mammals mostly had high bone mineral densities compared to the terrestrial species, which could be considered an adaptation to overcome buoyancy during swimming and shallow diving. Generally, it seems that different osteological properties at the levels of mineral density and biomechanics could be compatible with the adaptation to aquatic, semiaquatic, or terrestrial niches.
摘要：
先前记录的水生四足动物的四肢骨密度增加已被认为是克服游泳和潜水过程中浮力的一种适应方法。它可以通过增加骨沉积的量或通过减少骨吸收的量来实现，导致皮质增厚，髓腔丢失，和小梁骨的压实。本研究检查了运动习惯的影响，身体尺寸,和密度测量的系统发育，横截面,以及陆地股骨骨干和颈部的生物力学特征，半水生，和水生食肉动物，以及通过使用外周定量计算机断层扫描在陆地和半水生啮齿动物（12种）中，三点弯曲，和股骨颈负荷试验。使用单变量广义线性模型和多变量线性判别分析并辅以层次聚类进行分组差异分析。虽然没有一个个体特征可以充分区分生活方式或物种，多个特征的组合产生了非常好或极好的分类和聚类。在海豹中，水生生态位允许股骨矿物质密度低于仅基于体重的预期。与陆地物种相比，半水生哺乳动物大多具有较高的骨矿物质密度，这可以被认为是在游泳和浅水潜水过程中克服浮力的一种适应方法。一般来说,似乎在矿物质密度和生物力学水平上不同的骨骼特性可能与对水生生物的适应相容，半水生，或陆地生态位。
