SGER/Collaborative Research: Character Weighting of Nucleotide Sequence Data

分子数据提供了帮助解决 远亲生物之间的关系。 核苷酸 序列数据具有特别提供信息的潜力。 但是一个困难是只有四种字符状态 （代表四种不同的核苷酸） 在序列中。 如果分子快速变化或者时间 由于发散较长，因此在任何特定位置的多个取代 位置可能会模糊有关关系的信息， 有机体 如果我们知道哪些位置最有可能 持续多次替换，我们可能会提供信息， 在关系分析中的权重较小。 该项目将 测试一种确定哪些职位更有可能 已经持续了多次替换。 我们将获得序列 一个科内属的特定叶绿体基因的数据 并确定哪些核苷酸位置变化 在那个家庭里 然后，我们将获得相同的序列数据， 基因从一些不同的被子植物家庭，我们 对真实的关系有一个合理的想法。 我们将使用 一个家族内核苷酸序列变异信息 以帮助决定哪些核苷酸位置提供准确的 关于不同被子植物亲缘关系的信息。 的 关系分析结果的相似性， 关于多个替换的可能性的信息 真正的关系将被用来评估的功效， 法

Molecular data offer the possibility of helping to resolve relationships among distantly related organism. Nucleotide sequence data have the potential to be especially informative. But one difficulty is that there are only four character states (representing the four different nucleotides) at any one position in the sequence. If the molecule is changing rapidly or the time since divergence is long, multiple substitutions at any particular position may obscure information about relationships of the organisms. If we knew which positions were most likely to have sustained multiple substitutions we might give that information less weight in an analysis of relationships. This project will test one method of determining which positions are more likely to have sustained multiple substitutions. We will obtain sequence data of a particular chloroplast gene for genera within one family of flowering plants and determine which nucleotide positions vary within that family. We will then obtain sequence data of that same gene from a number of divergent angiosperm families for which we have a reasonable idea of the true relationships. We will use the information on variation in nucleotide sequence within one family to help decide which nucleotide positions provide accurate information on the relationships of the divergent angiosperms. The similarity of results of analyses of relationships using information on the likelihood of multiple substitution with the true relationships will be used to evaluate the efficacy of the method.