Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, 20971 Málaga, Spain.
BMC Evol Biol. 2014 Jun 14;14:129. doi: 10.1186/1471-2148-14-129.
The shape of the appendicular bones in mammals usually reflects adaptations towards different locomotor abilities. However, other aspects such as body size and phylogeny also play an important role in shaping bone design.We used 3D landmark-based geometric morphometrics to analyse the shape of the hind limb bones (i.e., femur, tibia, and pelvic girdle bones) of living and extinct terrestrial carnivorans (Mammalia, Carnivora) to quantitatively investigate the influence of body size, phylogeny, and locomotor behaviour in shaping the morphology of these bones. We also investigated the main patterns of morphological variation within a phylogenetic context.
Size and phylogeny strongly influence the shape of the hind limb bones. In contrast, adaptations towards different modes of locomotion seem to have little influence. Principal Components Analysis and the study of phylomorphospaces suggest that the main source of variation in bone shape is a gradient of slenderness-robustness.
The shape of the hind limb bones is strongly influenced by body size and phylogeny, but not to a similar degree by locomotor behaviour. The slender-robust "morphological bipolarity" found in bone shape variability is probably related to a trade-off between maintaining energetic efficiency and withstanding resistance to stresses. The balance involved in this trade-off impedes the evolution of high phenotypic variability. In fact, both morphological extremes (slender/robust) are adaptive in different selective contexts and lead to a convergence in shape among taxa with extremely different ecologies but with similar biomechanical demands. Strikingly, this "one-to-many mapping" pattern of evolution between morphology and ecology in hind limb bones is in complete contrast to the "many-to-one mapping" pattern found in the evolution of carnivoran skull shape. The results suggest that there are more constraints in the evolution of the shape of the appendicular skeleton than in that of skull shape because of the strong biomechanical constraints imposed by terrestrial locomotion.
哺乳动物附肢骨骼的形状通常反映了对不同运动能力的适应。然而，其他方面，如体型和系统发育，也在塑造骨骼设计方面发挥着重要作用。我们使用基于 3D 标志点的几何形态测量学来分析现生和已灭绝的陆生食肉动物（哺乳纲，食肉目）后肢骨骼（股骨、胫骨和骨盆带骨骼）的形状，以定量研究体型、系统发育和运动行为对这些骨骼形态的影响。我们还研究了在系统发育背景下形态变异的主要模式。
体型和系统发育强烈影响后肢骨骼的形状。相比之下，适应不同运动方式的特征似乎影响较小。主成分分析和系统发育形态空间研究表明，骨骼形状变异的主要来源是细长-粗壮度的梯度。
后肢骨骼的形状受体型和系统发育的强烈影响，但受运动行为的影响程度不同。骨骼形状变异性中发现的细长-粗壮“形态两极化”可能与维持能量效率和承受抵抗应力之间的权衡有关。这种权衡所涉及的平衡阻碍了高表型变异性的进化。事实上，形态的两个极端（细长/粗壮）在不同的选择环境中都是适应性的，导致具有非常不同生态但具有相似生物力学需求的类群在形状上趋同。引人注目的是，后肢骨骼形态与生态之间的这种“一对一映射”进化模式与食肉目头骨形状进化中的“多对一映射”模式完全相反。结果表明，由于陆地运动所施加的强烈生物力学限制，附肢骨骼形状的进化受到更多的限制，而不是头骨形状的进化。
