Analysis of the Genetic Diversity and Structure of the Grey-Faced Buzzard (Butastur indicus) in Japan, Based on mtDNA

Genetic Structure in Japanese and Thai Populations of the Japanese Sparrowhawk Accipiter gularis

The Japanese sparrowhawk Accipiter gularis is a small raptor that breeds in Northeast Asia. The species consists of the widespread and mostly migratory subspecies A. g. gularis that is common in East Asia, including Japan, and the resident and endangered subspecies A. g. iwasakii which inhabits the Ryukyu and Yaeyama Islands in Okinawa, southern Japan. Given the minimal knowledge about the migration of the species, in this study we sought to compare the genetic variation of the populations breeding in Japan with those migrating through Southeast Asia. We sequenced 761 bp of mitochondrial DNA Control Region from each of 21 A. gularis collected during the breeding season in Japan and from 20 individuals intercepted on migration in Thailand. We detected 26 haplotypes among the 41 individuals which differed significantly between Japan and Thailand. Migrants in Thailand were presumed to have originated from a wide area in Eastern Eurasia. The phylogenetic and network analyses demonstrated that the haplotypes of all A. g. gularis detected in Japan were genetically close. Moreover, the Okinawa haplotypes of A. g. iwasakii were clustered with moderate genetic variation. The information presented here can be used towards implementing future conservation actions.

Genetic Structure and Diversity of Two Populations of the Eastern Buzzard (Buteo japonicus japonicus and B. j. toyoshimai) in Japan

The nominotypical subspecies of the Eastern buzzard (Buteo japonicus japonicus; BJJ) is a common raptor inhabiting East Asia and Japan. Another subspecies, B. j. toyoshimai (BJT), inhabits only the Bonin Islands of the Ogasawara Islands, where there are only an estimated 85 breeding pairs. Because of this low population size, this subspecies is classified as endangered (class IB) in Japan. The aims of the present study were to examine genetic differences between BJJ and BJT, determine the genetic structure of the Eastern Buzzard, and assess genetic diversity within each subspecies. We sequenced 1526 bp within the control region of the mtDNA of 10 BJJ individuals during the breeding season in four sites; similarly, we sequenced 23 BJJ individuals during winter in three sites. We detected 24 haplotypes among the 33 individuals. In a similar analysis performed with 12 BJT individuals, three haplotypes were detected. The phylogenetic analysis showed that BJJ and BJT have diverged into distinct clades, supporting the genetic differentiation between the subspecies. Network and mismatch distribution analyses indicated that BJJ may have experienced population expansion. In addition, comparisons with other raptors revealed a high degree of genetic diversity in the BJJ population. In contrast, the genetic diversity of the BJT population is lower than that in other raptors. Our results indicated that it is necessary to protect BJT to prevent the reduction in its genetic diversity.