DISSERTATION RESEARCH: Independent evolution and ancestral conditions in the gnathostome axial column

论文研究：颚口轴柱的独立进化和祖先条件

• 批准号: 1501749
• 负责人: Michael Coates
• 金额: $ 2.03万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1501749&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Independent; evolution; ancestral

The presence of a backbone, even if only made of cartilage, is the feature that distinguishes vertebrate animals from their invertebrate relatives. Despite its central position in the body plans of all jawed vertebrates, the early evolutionary history and developmental mechanisms that gave rise to the vertebral column are not well understood. Across different vertebrate groups, and among fishes in particular, the vertebrae that make up the backbone are remarkably varied in their shape, composition, and structure. Furthermore, the early fossil record of the major groups of fishes shows that many evolved fundamental components of the vertebral column quite independently of others. The goals of this project are to document vertebral development in poorly studied groups such as sharks and skates, to determine how much independent evolution actually occurred in the deep history of vertebrae, and to provide essential comparisons with the current understanding of vertebral development in bony fishes.This project combines ancestral state reconstructions on gnathostome supertrees with computed tomography, gene expression, and fate mapping experiments to investigate the macroevolutionary patterns of vertebral evolution and development in fishes. Chondrichthyans are the main focus of the proposed research because they occupy a key phylogenetic position as the most proximate outgroup to the Osteichthyes. Chondrichthyans are often considered exemplars of ancestral vertebrate conditions in developmental and functional studies, but the primitive or derived status of much of their morphology is unclear and the subject of renewed research interest. Identifying ancestral conditions and homoplasy in the axial column complex is essential for the informed evaluation of studies and data obtained from alternative vertebrate model systems. Moreover, sharks as well as fossils are charismatic study subjects that effectively capture public interest. To help communicate the nature of this and other related projects to the public, the investigators will use computed tomographic scans (static and animated), and fossil shark specimens to educate students at local schools about the importance and relevance of evolutionary biology.

脊椎骨的存在，即使只是由软骨构成，也是脊椎动物区别于无脊椎动物亲戚的特征。尽管脊柱在所有有颌脊椎动物的身体结构中处于中心位置，但其早期进化历史和形成脊柱的发育机制尚不清楚。在不同的脊椎动物群体中，特别是在鱼类中，构成脊椎的椎骨在形状、组成和结构上都有很大的不同。此外，主要鱼类群体的早期化石记录表明，许多脊椎的基本组成部分是完全独立于其他部分进化而来的。该项目的目标是记录研究较少的群体（如鲨鱼和溜冰鱼）的椎体发育，以确定在椎骨的深层历史中实际发生了多少独立进化，并与目前对硬骨鱼类椎体发育的理解提供必要的比较。本项目将颌目超树的祖先状态重建与计算机断层扫描、基因表达和命运定位实验相结合，研究鱼类脊椎进化和发育的宏观进化模式。软骨鱼类是这项研究的主要焦点，因为它们在系统发育上占据了关键的位置，是与骨鱼类最接近的外群。在发育和功能研究中，软骨鱼通常被认为是祖先脊椎动物条件的典范，但它们的许多形态的原始或衍生状态尚不清楚，并且是新的研究兴趣的主题。确定祖先条件和轴柱复合体的同质性对于从其他脊椎动物模型系统获得的研究和数据的知情评估至关重要。此外，鲨鱼和化石都是有魅力的研究对象，能有效地吸引公众的兴趣。为了向公众宣传这个项目和其他相关项目的本质，研究人员将使用计算机断层扫描（静态和动态），以及鲨鱼化石标本，向当地学校的学生宣传进化生物学的重要性和相关性。