Dissertation Research: Integrative Study of the Evolution of Squamate Limb Reduction

PI：Crompton 9801134陆地脊椎动物(四足动物)的截肢是一种常见的现象。一些血统减少了四肢的总尺寸，或者完全失去了四肢，而另一些则简单地减少了骨骼的总数(两栖动物只有四个手指，鸟类只有三个手指)。尽管在四足动物中普遍存在肢体减少的现象，但这种现象背后的进化和发育机制却知之甚少。这项研究将采取一种综合的方法，通过澳大利亚蜥蜴Homeergis来了解截肢的形态、分子和功能方面。半人猿是研究截肢的理想模式生物，因为它的特征是在几个密切相关的物种的属内具有手指和脚趾的梯度(从5个手指和脚趾到2个手指和脚趾)。这项研究致力于比较不同物种半身人的骨骼发育模式，追踪肢体模式基因表达的变化，并记录伴随着肢体减少而发生的功能变化。截肢通常涉及一种常见的手指缺失顺序，对半身人发育的研究将为其他四足类动物的截肢提供洞察力。该项目还将阐明特定基因在构建胚胎肢体模式中的进化作用。

PI: Crompton 9801134 Limb reduction in terrestrial vertebrates (tetrapods) is a common phenomenon. Some lineages reduce the total size of their limbs or lose them altogether, while others simply reduce the total number of bones (amphibians have only four fingers and birds have only three). Despite the common occurrence of limb reduction in tetrapods, the evolutionary and developmental mechanisms underlying this phenomenon are poorly understood. This study will take an integrative approach to understanding the morphological, molecular, and functional aspects of limb reduction through the Australian lizard Hemiergis. Hemiergis is an ideal model organism for limb reduction studies because it features a gradient of digit configurations (from 5 fingers and toes to 2 fingers and toes) within a genus of several closely related species. This investigation endeavors to compare patterns of skeletal development in different species of Hemiergis, trace changes in the expression of limb patterning genes, and document the functional changes that accompany limb reduction. Limb reduction typically involves a common order of digit loss, and studies of Hemiergis development will provide insight into cases of limb reduction in other tetrapod groups. This project will also elucidate the evolutionary role of specific genes in patterrdng the embryonic limb.