Incidence of Multiple Paternity and Inbreeding in High-Density Brown Bear Populations on the Shiretoko Peninsula, Hokkaido, Japan

A study on the Shiretoko Peninsula, Japan, reveals that approximately 15% of brown bear litters result from multiple paternity, comparable to rates observed in Scandinavian populations despite differences in population density and litter size. The research also identified low but notable instances of inbreeding, including cases involving father-daughter matings (2.7%), maternal half-siblings (0.5%), and paternal half-siblings (1.8%). No evidence was found for mother-son or full-sibling matings. These findings suggest that male-biased dispersal plays a crucial role in limiting close inbreeding, offering insights into the genetic dynamics of high-density brown bear populations. The study genotyped 837 individuals at 21 microsatellite loci and analyzed parentage across 70-82 litters to derive these conclusions.

Shimozuru, M., Shirane, Y., Tsuruga, H., Yamanaka, M., Nakanishi, M., Ishinazaka, T., Kasai, S., Nose, T., Masuda, Y., Fujimoto, Y., Mano, T., & Tsubota, T. (2019). Incidence of Multiple Paternity and Inbreeding in High-Density Brown Bear Populations on the Shiretoko Peninsula, Hokkaido, Japan. Journal of Heredity, 110(3), 321–331. https://doi.org/10.1093/jhered/esz002