Department of Evolutionary Biology, University of Tartu and Estonian Biocentre, Tartu, Estonia.
PLoS One. 2009 Sep 30;4(9):e7276. doi: 10.1371/journal.pone.0007276.
Polymorphic Y chromosome short tandem repeats (STRs) have been widely used in population genetic and evolutionary studies. Compared to di-, tri-, and tetranucleotide repeats, STRs with longer repeat units occur more rarely and are far less commonly used.
In order to study the evolutionary dynamics of STRs according to repeat unit size, we analysed variation at 24 Y chromosome repeat loci: 1 tri-, 14 tetra-, 7 penta-, and 2 hexanucleotide loci. According to our results, penta- and hexanucleotide repeats have approximately two times lower repeat variance and diversity than tri- and tetranucleotide repeats, indicating that their mutation rate is about half of that of tri- and tetranucleotide repeats. Thus, STR markers with longer repeat units are more robust in distinguishing Y chromosome haplogroups and, in some cases, phylogenetic splits within established haplogroups.
Our findings suggest that Y chromosome STRs of increased repeat unit size have a lower rate of evolution, which has significant relevance in population genetic and evolutionary studies.
多态性 Y 染色体短串联重复（STR）已广泛应用于群体遗传和进化研究。与二核苷酸、三核苷酸和四核苷酸重复相比，重复单元较长的 STR 出现的频率更低，也远不那么常用。
为了根据重复单元大小研究 STR 的进化动态，我们分析了 24 个 Y 染色体重复位点的变异：1 个三核苷酸、14 个四核苷酸、7 个五核苷酸和 2 个六核苷酸位点。根据我们的结果，五核苷酸和六核苷酸重复的重复方差和多样性比三核苷酸和四核苷酸重复低约两倍，这表明它们的突变率约为三核苷酸和四核苷酸重复的一半。因此，具有较长重复单元的 STR 标记在区分 Y 染色体单倍群方面更稳健，并且在某些情况下，在已建立的单倍群内也存在系统发育分裂。
我们的发现表明，Y 染色体 STR 的重复单元大小增加，其进化速度较慢，这在群体遗传和进化研究中具有重要意义。
