A new perspective on biogeographic barrier in the flathead grey mullet (Pisces: Mugilidae) from the northwest Pacific.

This study was the first to reveal the coexistence of two lineages of flathead grey mullet in Korea. L2 was confined to the Jeju Island in Korea, implying a biogeographic boundary between the two lineages. The allopatric distribution and genetic heterogeneity between lineages may be affected by an ancient geographic isolation during the glacial period and maintained due to adaptation to oceanic characteristics. Collectively, the two lineages may be comprised of distinct species.