PDF(Pubmed)
Abstract：
The modular organization of tetrapod paired limbs and girdles, influenced by the expression of Hox genes is one of the primary driving forces of the evolution of animal locomotion. The increased morphological diversification of the paired limbs is correlated with reduced between-limb covariation, while correlation within the elements is usually higher than between the elements. The tailed amphibians, such as Lissotriton newts, have a biphasic lifestyle with aquatic and terrestrial environments imposing different constraints on limb skeleton. By employing the methods of computerized microtomography and 3D geometric morphometrics, we explored the pattern of morphological variation, disparity, modularity and morphological integration in the proximal parts of the anterior limbs of six species of Eurasian small bodied newts. Although the species significantly differ in limb shape, there is a great overlap in morphology of scapula and humerus, and there are no differences in morphological disparity. For the scapula, the shape differences related to the duration of the aquatic period are in length, depth and curvature. The shape of the humerus is not affected by the length of aquatic period, and shape differences between the species are related to robustness of the body. The length of aquatic period has statistically supported phylogenetic signal. The scapula and humerus are structures of varying modularity. For the humerus, the strongest support on the phylogenetic level was for the capitulum/shaft hypothesis, which can also be interpreted as functional modularity. For the scapula, the greatest support was for the antero-posterior hypothesis of modularity in case of Lissotriton vulgaris, which can be explained by different functional roles and muscle insertion patterns, while there was no phylogenetic modularity. The modularity patterns seem to correspond with the general tetrapod pattern, with modularity being more pronounced in the distal structure. The future research should include more salamandrid taxa with different habitat preferences and both adult and larval stages, in order to explore how size, phylogeny and ecology affect the morphology and covariation patterns of limbs.
摘要：
四足动物配对四肢和腰带的模块化组织，受Hox基因表达的影响是动物运动进化的主要驱动力之一。成对肢体的形态多样化增加与肢体间协变减少相关，而元素内的相关性通常高于元素之间的相关性。尾巴两栖动物，比如Lissotritonnewts，具有双相的生活方式，水生和陆地环境对肢体骨骼施加不同的约束。通过采用计算机显微层析成像和3D几何形态计量学的方法，我们探索了形态变异的模式，视差,六种欧亚小体new前肢近端的模块化和形态整合。尽管该物种的肢体形状显着不同，肩胛骨和肱骨的形态有很大的重叠,形态差异没有差异。对于肩胛骨，与水生期持续时间相关的形状差异在长度上，深度和曲率。肱骨的形状不受水生期长度的影响，物种之间的形状差异与身体的健壮性有关。水生期的长度具有统计上支持的系统发育信号。肩胛骨和肱骨是不同模块化的结构。对于肱骨来说，在系统发育水平上最有力的支持是头/轴假说，这也可以解释为功能模块化。对于肩胛骨，最大的支持是Lissotritonvulgaris案例中模块化的前后假设，这可以用不同的功能角色和肌肉插入模式来解释，而没有系统发育模块化。模块化模式似乎与一般的四足动物模式相对应，模块化在远端结构中更为明显。未来的研究应包括更多具有不同栖息地偏好以及成虫和幼虫阶段的salamandrid类群，为了探索大小，系统发育和生态学会影响四肢的形态和共变模式。
