Current population genetics of Japanese harbor seals: Two distinct populations found within a small area

Abstract

AbstractWe used microsatellite loci to understand the current population genetics of Japanese harbor seals, and found that they were subdivided into two distinct populations, one in Erimo and the other in eastern Hokkaido, despite being only 150 km apart and having no obvious geographical boundaries between them. Strong population subdivision between the two areas may be due to the small number of haul‐out sites and population size, and that a single habitat type is used for haul‐out sites in Japan. Also, at Erimo, there are numerous rocky reefs at a single haul‐out site that stretch up to 1.3 km offshore from land, while 10 haul‐out sites in eastern Hokkaido, separated by a maximum of 30 km, are interspersed along 75 km of the coast. The direction in which the rocky reefs stretch away from land or in which the haul‐out sites are facing may be limiting the movement of Japanese harbor seals and causing strong population subdivision between Erimo and eastern Hokkaido. No recent genetic bottlenecks were detected, although the seals in Erimo and eastern Hokkaido were reported to have experienced declines in population size over the past few decades.