Yeh Jennifer
Section of Integrative Biology, School of Biological Sciences, The University of Texas at Austin, 78712, USA.
Evolution. 2002 Mar;56(3):628-41. doi: 10.1111/j.0014-3820.2002.tb01372.x.
Miniaturization has evolved numerous times and reached impressive extremes in the Anura. I compared the skeletons of miniature frog species to those of closely related larger species to assess patterns of morphological change, sampling 129 species from 12 families. Two types of morphological data were examined: (1) qualitative data on bone presence and absence; and (2) thin-plate spline morphometric descriptions of skull structure and bone shape. Phylogenetic comparative methods were used to address the shared history of species. Miniature anurans were more likely to lose skull bones and phalangeal elements of the limbs. Their skulls also showed consistent differences compared to those of their larger relatives, including relatively larger braincases and sensory capsules, verticalization of lateral elements, rostral displacement of the jaw joint, and reduction of some skull elements. These features are explained by functional constraints and by paedomorphosis. Variation among lineages in the morphological response to miniaturization was also explored. Certain lineages appear to be unusually resistant to the morphological trends that characterize miniature frogs as a whole. This study represents the first large-scale examination of morphology and miniaturization across a major, diverse group of organisms conducted in a phylogenetic framework and with statistical rigor.
小型化已经多次进化，并在无尾目中达到了令人瞩目的极端程度。我将小型蛙类物种的骨骼与亲缘关系相近的大型物种的骨骼进行比较，以评估形态变化模式，从12个科中选取了129个物种进行采样。研究了两种类型的形态学数据：（1）关于骨骼有无的定性数据；（2）对头骨结构和骨骼形状的薄板样条形态测量描述。系统发育比较方法被用于处理物种的共同历史。小型无尾目动物更有可能失去头骨骨骼和四肢的指骨。与它们的大型亲属相比，它们的头骨也表现出一致的差异，包括相对较大的脑壳和感觉囊、侧向元素的垂直化、下颌关节的喙状移位以及一些头骨元素的减少。这些特征可以通过功能限制和幼态持续来解释。还探讨了不同谱系在对小型化的形态学反应方面的差异。某些谱系似乎对表征整个小型蛙类的形态学趋势具有异常的抵抗力。这项研究是在系统发育框架内并以统计严谨性对一个主要的、多样化的生物群体进行的首次大规模形态学和小型化研究。
