DISSERTATION RESEARCH: The relative roles of selection and constraint in convergent ear loss across the true toads (Bufonidae)

中耳和外耳结构用来听声音，大多数陆地动物都有中耳和外耳结构。尽管青蛙和蟾蜍利用听力来寻找配偶，但许多青蛙和蟾蜍已经失去了他们的中耳和外耳结构。该项目旨在发现导致蟾蜍耳朵丧失进化的基因变化。由于其他陆地动物(包括人类)的中耳和外耳使用类似的发育途径，了解导致蟾蜍耳朵丧失的遗传变化将有助于阐明其他动物中耳和外耳丧失和畸形的潜在原因。这项研究产生的遗传数据将有助于我们更好地了解蟾蜍物种之间的关系，并为未来的研究提供新的遗传数据。除了研究生培训外，还将利用该项目产生的标本和数据创建互动博物馆展示，并将开发一系列K-12课堂练习来解释蟾蜍的耳朵结构进化。该项目调查了导致真蟾科(蟾科)中耳和外耳结构趋同丧失和潜在恢复的选择压力和遗传约束。将分析跨越7个耳朵损失事件的60个蟾蜍物种(16个无耳，44个有耳)的序列数据，以识别与中耳和外耳发育有关的50个基因的选择特征和平行的遗传变化。该数据集将评估各种选择压力的影响，并在遗传水平上寻找限制的证据，补充研究小组先前收集的大量表型水平选择和限制的证据。该项目的结果将描述选择和限制在驱动整个蟾科耳部损失中的作用，并阐明选择可能在受限的、可能代价高昂的性状损失中起作用的常见遗传途径。

Middle and outer ear structures are used for hearing sound and are shared by most land animals. Although frogs and toads use hearing to find a mate, many frogs and toads have lost their middle and outer ear structures. This project aims to discover the genetic changes that have resulted in the evolution of ear loss in toads. Since the middle and outer ears of other land animals (including humans) use similar developmental pathways, understanding the genetic changes that result in ear loss in toads will illuminate potential causes of middle and outer ear loss and malformation in other animals. The genetic data produced by this study will help us better understand the relationships between toad species and provide novel genetic data for future research. In addition to graduate training, interactive museum displays will be created from the specimens and data generated from the project, and a series of K-12 classroom exercises will be developed to explain the ear structure evolution in toads.This project investigates the selection pressures and genetic constraints that generate convergent loss and potential regain of middle and outer ear structures across the family of true toads (Bufonidae). Sequence data for 60 bufonid species (16 earless, 44 eared) spanning seven ear loss events will be analyzed to identify signatures of selection and parallel genetic changes across 50 genes involved in middle and outer ear development. The dataset will assess the effects of various selection pressures and look for evidence of constraint at the genetic level, complementing the large amount of evidence for selection and constraint at the phenotypic level that has previously been collected by the research team. Results of this project will delineate the roles of selection and constraint in driving ear loss across Bufonidae, and elucidate common genetic pathways by which selection can act in a constrained, potentially costly, trait loss.