Patterns of molecular evolution in avian microsatellites
Patterns of molecular evolution in avian microsatellites
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DOI：
10.1093/oxfordjournals.molbev.a026015
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发表时间：
1998-08-01
影响因子：
10.7
通讯作者：
Ellegren, H
中科院分区：
文献类型：
--
作者：
Primmer, CR;Ellegren, H
为了开发适当反映微卫星进化的模型，需要更多的知识，这些简单的序列演变的过程。在这项研究中，历史上的突变事件属于不同类别的重复类型（一个完美的双，一个复合双，和一个完美的四核苷酸重复）的三个鸟类微卫星位点进行了检查的76个等位基因的序列分析，在39个物种跨越鸟类遗传。进化的模式和克里思在不同的地点之间有很大的差异。对于完美的二核苷酸重复，当等位基因包含少至6或7个重复单位时，检测到种内长度多态性，并且对于短至（AG）的重复，证明了在进化时间尺度上的大小扩展（2）。一个显着水平的片段稳定性被发现的化合物二核苷酸重复，即使在物种被认为已经分歧超过60 MYA，符合高水平的引物序列保守在这个位点。相比之下，高变（AAAG）（n）基因座在重复区显示出非凡的不稳定性和结构异质性，包括衍生重复基序的长阵列，如（AG）（n），（AAGG）（n），（AAAAG）（n），甚至（AAAGAGAG）（n）。通常，在同一等位基因内可以发现几个基序。大量的情况下，等位基因大小的同源性检测所有三个位点。这些研究结果加强了这样一个事实，即在系统发育研究中使用之前，应更加注意标记的重复类型和突变特征。
In order to develop models which appropriately reflect microsatellite evolution, more knowledge is required about the processes by which these simple sequences evolve. In this study, historical mutation events in three avian microsatellite loci belonging to distinct classes of repeat types (one perfect di-, one compound di-, and one perfect tetranucleotide repeat) were examined by sequence analysis of 76 alleles in 39 species spanning the avian phylogeny. The mode and tempo of evolution varied greatly between loci. For the perfect dinucleotide repeat, intraspecific length polymorphism was detected when alleles contained as few as six or seven repeat units, and size expansion over evolutionary timescales was demonstrated for repeats as short as (AG)(2). A remarkable level of fragment stability was found for the compound dinucleotide repeat, even in species thought to have diverged over 60 MYA, coinciding with a high level of primer sequence conservation at this locus. In contrast, a hypervariable (AAAG)(n) locus revealed extraordinary instability and structural heterogeneity in the repeat region, including long arrays of derivative repeat motifs such as (AG)(n), (AAGG)(n), (AAAAG)(n), and even (AAAGAGAG)(n). Often, several motifs could be found within the same allele. A large number of cases of allele size homoplasy were detected for all three loci. These findings reinforce the fact that greater attention should be paid to the repeat type and the mutational charateristics of a marker before use in phylogenetic studies.