Autosomal and Y-chromosomal STR markers reveal a close relationship between Hokkaido Ainu and Ryukyu islanders

Abstract

Understanding the phylogenetic relationship between Hokkaido Ainu and Ryukyu islanders has been of great interest in human genetics, archaeology, and anthropology. We examined short tandem repeat (STR) polymorphisms on autosomes and Y-chromosomes for Ainu, and compared this with data from Ryukyu islanders. A statistical test for nine autosomal (A-STR) loci gave no indication that the Ainu had experienced any bottleneck effect(s). The genetic distances (R_st) based on the A-STR data consistently showed substantial differentiation between the Ainu and all other populations. The haplotype analysis based on Y-chromosomal (Y-STR) data revealed 10 distinct haplotypes found in 19 Ainu males; 7 out of 10 were Ainu-specific haplotypes, whereas two haplotypes were shared with two males from main-island Okinawa and Miyako island, respectively, indicating a strong, close relationship between the Ainu and the Ryukyu islanders. The time to the most recent common ancestor of the Y-lineages obtained in the Ainu and the Ryukyu islanders was estimated to be 37745 years ago. Overall, the A-STR showed uniqueness of the Ainu, and the Y-STR haplotypes revealed strong evidence for a link between the two indigenous populations of the Hokkaido and the Ryukyu islands.