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

这个项目试图通过对蝙蝠蹄的调查来更好地理解进化的新颖性和解剖学的多样性，蝙蝠蹄是一种在蝙蝠脚上发现的骨骼元素，而在其他哺乳动物的脚上却没有。卡尔卡是一种“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。蝙蝠的蹄骨特别特殊，因为它在不同的蝙蝠物种中差异很大，这表明解剖上的差异可能具有功能和生态意义。因此，足跖骨为研究脊椎动物产生解剖学新颖性和多样性的过程提供了一个独特的模型系统。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，以解释掌的进化，并探索其在蝙蝠全球辐射中的功能相关性。研究人员还将创建教育和推广活动，以促进跨学科研究的效用，以解决生物学中持久的问题。研究人员的主要目标是利用蝙蝠（翼目）的骨来了解发育变化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可变性。该项目的具体目标是：1)揭示蝙蝠跟骨的发育起源，辨别蝙蝠跟骨的同源性；2)确定导致跟骨之间结缔组织组成差异的发育过程（即，为什么有些跟骨会钙化或骨化，而另一些不会）。这些目标将通过对蝙蝠胚胎进行组织化学和免疫荧光分析来解决，这些胚胎代表了物种的系统发育、形态和生态多样性。这些实验将扩展研究人员最近在骨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验证他们的总体假设的能力：骨的进化是由于软骨形成和骨化的发育调节的改变导致适应性进化。

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.