Dissertation Research: Osteological Size and Shape Variation and the Evolution of Ossification Sequence in Ostariophysan Fishes

切尔诺夫和托马斯目前对生物体形态的研究强调，发育过程的变化是相关物种形状、大小和形式差异的根本。发育事件时间的相对简单的变化可能会导致两个相关谱系之间显著的形态差异。该项目由研究生凯瑟琳·托马斯在巴里·切尔诺夫博士的指导下进行，旨在通过比较四种淡水鱼的骨骼发育来研究发育时间和形态变化之间的关系。鱼的骨骼由许多在空间和功能上相关的骨骼元素组成，每个元素的生长过程中的一个重要事件是骨骼开始骨化(或吸收钙盐)的时间。因此，骨化时间的改变可能会强烈影响成人的形态。这项研究将记录代表骨藻超目主要谱系的四种鱼类的骨骼发育模式，骨藻超目主要是淡水鱼类的集合，包括鲶鱼、四鱼和它们的近亲。骨骼骨化的发育时间将被记录下来，这一信息将用于解决以下三个问题。1)近缘物种之间骨化的相对时间有多大的差异？2)任何一组骨骼在其骨化时间上是否在物种之间表现出高度的相关性，这表明该组元素之间存在很强的功能或发育相关性？3)骨骼的发育时间与其大小和形状的变化之间是否存在关系？回答这些问题将加强我们对发育模式和过程的变化如何调节形态多样化的了解。

0073267Chernoff and ThomasCurrent studies of the morphology of organisms emphasize the idea that changes in developmental processes are fundamental to differences in the shape, size, and form of related species. A relatively simple shift in the timing of a developmental event can potentially result in striking morphological divergence between two related lineages. This project, by graduate student Katherine Thomas under the direction of Dr. Barry Chernoff, seeks to investigate the relationship between developmental timing and morphological change by comparing skeletal development in four lineages of freshwater fishes. The fish skeleton is composed of numerous spatially and functionally related bony elements, and an important event in the growth of each element is the time at which the bone begins to ossify (or take up calcium salts). Thus, changes in the timing of ossification events may strongly influence adult morphology. This study will document patterns of skeletal development in four fish species representing the major lineages within the superorder Ostariophysi, an assemblage of primarily freshwater fishes including catfishes, tetras, and their relatives. The developmental times at which bones ossify will be recorded, and this information will be used to address the following three questions. 1) How variable is the relative timing of bone ossification among related species? 2) Do any sets of bones appear to be highly correlated among species in the time at which they ossify, suggesting strong functional or developmental associations among the elements of the set? 3) Is there a relationship between the developmental time at which a bone ossifies and its variation in size and shape? Answering these questions will strengthen our knowledge of how changes in developmental patterns and processes mediate morphological diversification.