Status and Perspective of the Blakiston’s Fish Owl Population, Based on Genetic Diversity

Blakiston’s fish owl (Bubo blakistoni) was formerly widespread on Hokkaido island, but its population size decreased during the twentieth century due to reduction and fragmentation of its habitat through human activities. To reveal the temporal and spatial changes in population structure and genetic diversity of this fish owl species, molecular phylogeny and population genetics were investigated on more than 400 specimens including old museum specimens of about 100 years old. The results by mitochondrial DNA haplotype and microsatellite analyses showed that the population on Hokkaido was recently fragmented into small local populations. Most haplotypes were previously widespread across Hokkaido but have become fixed in local areas after the 1980s. Genetic differentiations among local populations were indicated from both mitochondrial DNA and microsatellite data and could have arisen through population fragmentation. Decrease of genetic diversity in the Hokkaido population was observed in mitochondrial DNA haplotype, microsatellite, and the major histocompatibility complex (MHC) genes. The comparative analysis using samples from Primorye of the continent showed that their mitochondrial DNA sequences were remarkably differentiated from those of the Hokkaido population. In addition, the variations of microsatellite and MHC class II B genes in the Primorye population, which is larger and stable, were higher than those of the Hokkaido population.