DISSERTATION RESEARCH: Developmental mechanisms of morphological novelty and adaptation in the hindlimbs of bats (Chiroptera)

该项目旨在通过对蝙蝠脚距的调查，更好地了解进化的新奇和解剖学的多样性，这是一种在蝙蝠脚中发现的骨骼元素，但在其他哺乳动物的脚中没有。骨距是一种“新形态”，它突然出现在最早的蝙蝠身上，但在它们的祖先身上却没有发现：它在化石记录中的出现很难解释。蝙蝠的骨距是特别特殊的，因为它在蝙蝠物种之间变化很大，这表明解剖学上的变化可能具有功能和生态意义。因此，股骨距提供了一个独特的模型系统，研究过程中产生的解剖新奇和多样性的脊椎动物。在这个项目中，研究人员将把发育生物学和生物力学的方法联系起来，以解释骨距的进化，并探索其在蝙蝠全球辐射中的功能相关性。研究人员还将开展教育和推广活动，以促进跨学科研究在解决生物学持久问题方面的效用。研究人员的主要目标是利用蝙蝠（翼手目）的距来了解发育修饰如何导致新骨骼结构的形成以及这些结构中与功能相关的变异。该项目的具体目标是：1）揭示距的发育起源，并辨别其在蝙蝠中的同源性; 2）确定导致距之间结缔组织组成差异的发育过程（即，为什么有些股骨距钙化或骨化，而另一些则没有）。这些目标将使用蝙蝠胚胎的组织化学和免疫荧光检测来解决，这些蝙蝠胚胎代表了遗传学、形态学和生态学上的多样性物种。这些实验将扩展研究人员最近在股骨距功能解剖学和生物力学方面的工作。该项目将加强研究人员测试其总体假设的能力：由于软骨形成和骨化的发育调节的修改导致适应性进化，导致了骨距的进化。

This project seeks to better understand evolutionary novelty and anatomical diversity through an investigation of the bat calcar, a skeletal element found in bat feet but not in the feet of other mammals. The calcar is a 'neomorphism,'it suddenly appears in the earliest bats but is not found in their ancestors: its appearance in the fossil record is difficult to explain. The bat calcar is particularly exceptional because it varies extensively across bat species, suggesting that anatomical variation may have functional and ecological implications. Therefore, the calcar offers a unique model system for studying the processes that generate anatomical novelty and diversity in vertebrates. In this project, the researchers will link approaches from developmental biology and biomechanics in order to explain the evolution of the calcar and to explore its functional relevance across the global radiation of bats. The researchers will also create education and outreach activities that will promote the utility of interdisciplinary research for solving enduring questions in biology.The researchers' primary goal is to use the calcar of bats (Chiroptera) to understand how developmental modifications can lead to the formation of novel skeletal structures and to functionally-relevant variability in those structures. The specific objectives of this project are to 1) reveal the developmental origin of the calcar and discern its homology among bats, and 2) identify developmental processes that lead to differences in connective tissue composition among calcars (i.e., why some calcars calcify or ossify while others do not). These objectives will be addressed using histochemical and immunofluorescent assays of bat embryos representing phylogenetically, morphologically, and ecologically diverse species. These experiments will expand on the researchers' recent work on calcar functional anatomy and biomechanics. This project will strengthen the ability of the researchers to test their overarching hypothesis: the evolution of the calcar resulted from modifications in developmental regulation of chondrogenesis and ossification leading to adaptive evolution.