組換現象に着目した集団ハプロタイプ構造解析法 : 分かれと出会いの系統地理学(2011年度日本動物分類学会シンポジウム)

抄録

In this review article, we describe a recently developed method that explores past introgressive hybridization following secondary contact, focusing on recombination signals along a certain chromosome portion, such as 200 kb, 1 Mb, or 5 Mb. In a case of 200 kb segment, for example, we determined nucleotide sequences in eight gene region (〜500 bp) being separated at 20-30 kb interval and assessed its haplotype structures. This allows us to estimate the time since hybridization has occurred, assuming that the lengths of introgressed segments reflect the times of generation. We applied this method to capture missed evolutionary episodes of the house mouse Mus musculus occurring in the Japanese Islands, where different subspecies lineages are known to be mingled. We detected the recombinant haplotypes not only between north Eurasian (M. m. musculus) and East Asian (M. m. castaneus) lineages but also between north Eurasian and East European (M. m. domesticus) lineages, with relatively shorter and longer introgressed segments, respectively. These results suggest that the Japanese wild mice with the genetic background of M. m. musculus experienced ancient and recent genetic introgression with M. m. castaneus and M. m. domesticus, respectively. Further efforts would be needed to improve the method, aiming at establishment of ways to fully utilize the genetic information related to recombination events in molecular phylogeographic study.