Reconciling Molecular and Fossil Evidence on the Age of Angiosperms

调和关于被子植物年龄的分子和化石证据

• 批准号: 9726856
• 负责人: Michael Sanderson
• 金额: $ 15万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9726856&HistoricalAwards=false
• 关键词: Reconciling; Molecular; Fossil; Evidence; Age

9726856 Sanderson The age of the angiosperms has long been a topic of controversy in plant evolution. Traditionally, the problem was addressed primarily from a paleobotanical point of view. However, molecular studies relying on the hypothesis of a constant rate of evolution ("molecular clock") have added a new dimension to the problem, often suggesting a much older age than does fossil evidence. Many of these analyses conflict with each other, and therefore they call into question not only paleobotanical assumptions but also the validity of the molecular clock, a major issue in molecular evolution. Drs. Sanderson and Doyle will undertake a critical evaluation of the implications of molecular evidence for the age of angiosperms, especially its agreement or disagreement with fossil evidence, using both new data and new methods of analysis. They propose to combine existing and new sequence data from rbcL, atpB, and 18S rDNA genes with new data to be obtained from four slowly evolving chloroplast genes. Sampling of taxa will emphasize angiosperms with a good Cretaceous fossil record or which represent early branches in the angiosperm tree in addition to other relevant seed plants. Using new methodologies that allow hypothetical rates of evolution to vary, we hope to obtain a better assessment of (1) the error in molecular estimates of the age of angiosperms and the sources of those errors, and (2) the level of disagreement between fossil evidence for the age of angiosperms and molecular estimates when the error in divergence times is taken into account. Methods and insights derived from this study may be useful in dating other groups where there are apparent conflicts between molecular and fossil data.

小行星9726856 被子植物的年龄在植物进化中一直是一个有争议的话题。 传统上，这个问题主要从古植物学的角度来解决。 然而，依赖于恒定进化速率假设（“分子钟”）的分子研究为这个问题增加了一个新的维度，通常表明比化石证据更古老的年龄。 许多这些分析相互矛盾，因此他们不仅质疑古植物学假设，而且质疑分子钟的有效性，这是分子进化中的一个主要问题。 Sanderson和Doyle博士将利用新数据和新分析方法，对分子证据对被子植物年龄的影响进行批判性评估，特别是与化石证据的一致性或不一致性。 他们建议将来自rbcL、atpB和18S rDNA基因的现有和新的序列数据与从四个缓慢进化的叶绿体基因获得的新数据联合收割机结合。 分类群的取样将强调被子植物与一个良好的白垩纪化石记录或代表早期分支的被子植物树除了其他相关的种子植物。 使用新的方法，允许假设的进化速率变化，我们希望获得一个更好的评估（1）的错误分子估计的被子植物的年龄和这些错误的来源，（2）之间的分歧程度的化石证据的被子植物的年龄和分子估计时，分歧时间的错误被考虑在内。 从这项研究中得出的方法和见解可能有助于确定分子和化石数据之间存在明显冲突的其他群体的年龄。