Recent fragmentation of the endangered Blakiston's fish owl (Bubo blakistoni) population on Hokkaido Island, Northern Japan, Revealed by Mitochondrial DNA and Microsatellite Analyses.

Keita Omote,Chizuko Nishida,Keisuke Saito,Takao Sato,Takeshi Takenaka,Ryohji Shimura,Ryuichi Masuda,Satoshi Fujimoto

doi:10.1186/s40851-015-0014-3

Keita Omote, Chizuko Nishida + Show 6 more

Open Access

https://doi.org/10.1186/s40851-015-0014-3

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Abstract

IntroductionBlakiston’s fish owl (Bubo blakistoni) was previously widespread on Hokkaido Island, Japan, but is now distributed only in limited forest areas. The population size on Hokkaido decreased during the 20th century due to reduction and fragmentation of the owl’s habitat. To elucidate temporal and spatial changes in population structure and genetic diversity, we analyzed 439 individuals collected over the last 100 years.ResultsWe detected a population bottleneck and fragmentation event indicated by mitochondrial DNA (mtDNA) haplotype and microsatellite analyses. The lowest value for effective population size, which was estimated by moment and temporal methods from microsatellite data, occurred in the 1980s. Five haplotypes were found in the mtDNA control region; most haplotypes were previously widespread across Hokkaido, but have become fixed in separate areas after the bottleneck period. Genetic differentiation among local populations, as indicated by both mtDNA and microsatellite data, likely arose through population fragmentation.ConclusionsThe owl population may have been divided into limited areas due to loss of habitats via human activities, and have lost genetic variability within the local populations through inbreeding. Our mtDNA and microsatellite data show that genetic diversity decreased in local populations, indicating the importance of individuals moving between areas for conservation of this species on Hokkaido.

Highlights

Blakiston’s fish owl (Bubo blakistoni) was previously widespread on Hokkaido Island, Japan, but is distributed only in limited forest areas
Variation and distribution of mitochondrial DNA (mtDNA) haplotypes Part of the mtDNA control region (590 bp) was sequenced for 150 individuals, including the old museum and archaeological samples; sequences were obtained for 31 stuffed specimens and three archeological bones
Our study demonstrates that the genetic diversity in local populations decreased for the last 30 years due to population fragmentation, and that even a few movements among local populations may counter this decline in genetic diversity in Blakiston’s fish owls

Summary

Introduction

Blakiston’s fish owl (Bubo blakistoni) was previously widespread on Hokkaido Island, Japan, but is distributed only in limited forest areas. Blakistoni on Hokkaido and the southern Kuril islands (Figure 1) [1] This species is resident in riparian forests and requires a large quantity of fish for food and large hollow trees for nesting [2,3]. It can reach ages of over 20 years and inhabits restricted territories along rivers; the clutch size is usually two eggs [3,4].

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