Dissertation Research: Developmental Bases of Anolis Limb Evolution

论文研究：动物肢体进化的发育基础在过去的二十年中，对宏观进化时间尺度上发育过程变化的理解取得了进展，极大地提高了对世界生物多样性产生机制和过程的认识。通过关注物种内部和物种之间的历史和机制研究来补充宏观进化方法，将大大提高对形态进化过程的理解。最近在进化和发育生物学领域的分析和技术进步使得现在是整合这些学科和研究形态变化背后的微观进化过程的完美时机。特别令人感兴趣的是发育变异性和进化分化之间的关系。这种关系很重要，因为在产生发育变异方面的偏见可以被视为促进或限制进化变化，这分别取决于选择和较大或较小变异的维度之间的关系。在他们的研究中，吉布森-布朗博士和他的学生托马斯·桑格将利用在大安的列斯群岛的每个岛屿（古巴、伊斯帕尼奥拉岛、牙买加和波多黎各）上已经得到充分研究的蜥蜴的生态形态。他们建议研究蜥蜴肢体形态在多个生物层次（形态、细胞和分子）的趋同进化过程中发育机制的变化。他们将专门测试不同物种通过相同的发育机制进化出相似的肢体长度的假设。为了验证这一假设，他们的研究分为三个具体目标。他们将首先比较每个岛屿上长肢和短肢物种的相对生长情况，以确定在发育过程中确定四肢长度差异的时间。利用这些信息，他们将研究这些时期骨骼生长的细胞机制，以比较生长速率变化的发育机制。最后，他们将开始通过检查被认为在生长板中表达差异的基因来确定导致物种之间生长差异的分子机制。这也是三十多年来首次对爬行动物骨骼生长进行研究。这项研究有几个更广泛的影响超出了这个项目的范围。吉布森-布朗博士和桑格先生积极支持未被充分代表的少数民族参与这项研究项目，包括学生和教师。他们每学期都有几名本科生研究助理，其中一些人进行自己的相关研究项目。他们的工作还促进了几个生物学科和大学之间的合作。

Dissertation Research: The Developmental Bases of Anolis Limb EvolutionJeremy J. Gibson-Brown and Thomas J. SangerWashington University in Saint Louis In the past twenty years, advances in understanding of how developmental processes change over macroevolutionary time scales have greatly improved knowledge about the mechanisms and processes responsible for generating the world's biological diversity. Complementing the macroevolutionary approach with research focusing on historical and mechanistic studies, both within and between closely related species, will greatly enhance understanding of the processes underlying morphological evolution. Recent analytical and technical advances in the fields of evolutionary and developmental biology make this the perfect time to integrate these disciplines and to investigate the microevolutionary processes underlying morphologic change. Of particular interest are the relationships between developmental variability and evolutionary divergence. This relationship is important because a bias in the production of developmental variation could be viewed as facilitating or constraining evolutionary change, depending on the relationship between selection, and dimensions of greater or lesser variation, respectively. For their research Dr. Gibson-Brown and his student, Thomas Sanger, will take advantage of the well-studied ecomorphs of Anolis lizards on each island of the Greater Antilles: Cuba, Hispaniola, Jamaica, and Puerto Rico. They propose to study how developmental mechanisms have changed during the convergent evolution of lizard limb morphologies at multiple levels of the biological hierarchy (morphological, cellular, and molecular). They will specifically test the hypothesis that different species have evolved similar limb lengths using the same developmental mechanisms. To test this hypothesis their study is divided into three specific aims. They will first compare the relative growth of long-limbed and short-limbed species on each island to establish the time during development that limb length differences are determined. Using this information they will then examine the cellular mechanisms of bone growth at these times to compare the developmental mechanisms by which growth rates are changing. Finally, they will begin to identify the molecular mechanisms leading to differences in growth between species by examining genes thought to be differentially expressed in the growth plates. This will also be the first study to examine reptilian bone growth in over thirty years. This research has several broader impacts beyond the scope of this project. Dr. Gibson-Brown and Mr. Sanger actively support the participation of underrepresented minorities in this research project, including students and teachers. They incorporate several undergraduate research assistants each semester, some of whom conduct their own related research projects. Their work has also fostered collaborations between several biological disciplines and universities.