Developmental Evolution of Avian Digit Homology

鸟类数字同源性的发育进化

• 批准号: 0445971
• 负责人: Gunter Wagner
• 金额: $ 43.48万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0445971&HistoricalAwards=false
• 关键词: Developmental; Evolution; Avian; Digit; Homology

Project SummaryEver since the discovery of the dinosaur affinities of birds, a discrepancy has persisted between the developmental and the phylogenetic evidence regarding the identity of digits in the bird wing. The preponderance of phylogenetic evidence demonstrates that the three permanent fingers of birds are digits one, two and three, while the embryological evidence demonstrates that these fingers develop from the anlagen that, in other animals, develop into digits two, three and four. Recent results from the laboratory of Dr Fallon, University of Wisconsin, shows that there is a gene expression signature which can distinguish between digit one and digit two, and which supports the hypothesis that the fingers of birds are in fact digits one, two and (by inference) three. Specifically the expression of Hoxa-13, Hoxd-13, and Hoxd-12 is seen in all digits posterior of digit one, while digit one does not express Hoxd-12. This grant funds a collaborative effort between a developmental biology lab (Dr Fallon, University of Wisconsin) and an evolutionary biology lab (Dr Wagner, Yale University) to follow up on this result. The goal of this project is to validate the inference from gene expression pattern to digit identity by using both experimental as well as comparative data. Objectives: 1) test whether the expression patterns of Hoxa-13, Hoxd-13, and Hoxd-12 are causally relevant for the development of digit morphology. 2) Determine whether the association between Hox gene expression patterns and digit identity, as described by Dr's Vargas and Fallon, is conserved among major groups of tetrapods and in the face of natural variation in digit number. To meet objective 1 Dr Fallon will study the effect of Hoxd-12 misexpression in the digit one anlage as well as knockdown of Hoxa-13 and Hoxd-13. To meet objective 2, Dr Wagner will study the expression of Hoxa-13, Hoxd-13, and Hoxd-12 in alligator, frog and lizard embryos including two species which have lost digit one during evolution, Hemiergis peronii and Chalcides chaldices (skinks). Intellectual merit: while the identity of bird digits can be seen as a subject of limited importance, the persisting disagreement among major scientific disciplines about a matter of scientific fact raises concern. Unresolved high profile controversies like this can have a corrosive effect on the disciplinary integration of evolutionary and developmental biology. For that reason the proposed project seeks to resolve this issue with a combined developmental and evolutionary approach seeking a convergence of evidence between them. Broader impact: The broad impact of this proposal is measured in two ways: (1) by employing a highly interdisciplinary approach for evaluating a complex problem in evolutionary developmental biology; and (2) by providing a wealth of research and educational resources. These training opportunities include postdoctoral training and new summer traineeships for teachers.

自从发现鸟类与恐龙的亲缘关系以来，关于鸟类翅膀趾的同一性的发育证据和系统发育证据之间的差异一直存在。系统发育证据的优势表明，鸟类的三个永久手指是指一、指二和指三，而胚胎学证据表明，这些手指是从其他动物的原纤维发育成指二、指三和指四的。威斯康辛大学法伦博士实验室最近的研究结果表明，有一种基因表达特征可以区分数字1和数字2，这支持了鸟类手指实际上是数字1、2和（由此推断）3的假设。具体来说，Hoxa-13、Hoxd-13和Hoxd-12在数字1后的所有手指中都有表达，而数字1不表达Hoxd-12。这项拨款资助了一个发育生物学实验室（威斯康辛大学法伦博士）和进化生物学实验室（耶鲁大学瓦格纳博士）之间的合作，以跟进这一结果。该项目的目标是通过使用实验和比较数据来验证从基因表达模式到数字身份的推断。目的：1)检测Hoxa-13、Hoxd-13、Hoxd-12的表达模式与趾形态发育是否存在因果关系。2)确定Vargas和Fallon博士所描述的Hox基因表达模式与手指身份之间的关联，是否在四足动物的主要群体中以及面对手指数量的自然变化时是保守的。为了实现目标1，Fallon博士将研究Hoxd-12在手指1的错误表达以及Hoxa-13和Hoxd-13的敲低的影响。为了实现目标2，Wagner博士将研究Hoxa-13、Hoxd-13和Hoxd-12在鳄鱼、青蛙和蜥蜴胚胎中的表达，其中包括两个在进化过程中失去了数字1的物种，Hemiergis peronii和Chalcides chaldices（石龙子）。智力价值：虽然鸟类趾的身份可以被视为一个有限的重要课题，但主要科学学科之间对科学事实问题的持续分歧引起了关注。像这样悬而未决的高调争议可能会对进化生物学和发育生物学的学科整合产生腐蚀性影响。因此，拟议的项目试图以发展和进化相结合的方法解决这一问题，寻求两者之间证据的融合。更广泛的影响：该提案的广泛影响可以通过两种方式衡量：(1)采用高度跨学科的方法来评估进化发育生物学中的复杂问题；(2)提供丰富的研究和教育资源。这些培训机会包括博士后培训和新的暑期教师培训。