Large-scale genetic structure and diversity of Arctic rainbow smelt Osmerus dentex Steindachner et Kner, 1870 throughout its distributional range based on microsatellites

Arctic rainbow smelt Osmerus dentex is one of the most abundant fish species widely distributed in the NW Pacific and Arctic seas. Studying this species can contribute to understanding the microevolutionary processes of the Arctic fauna in unstable climatic conditions and new habitats. However, little is known about the genetic structure and the mechanisms underlying its population dynamics. Ten microsatellite loci were used to genotype 822 individuals in 20 locations throughout a large part of the species’ range in the Sea of Japan, Sea of Okhotsk, Bering, Kara, and White seas (across more than 11,000 km). O. dentex displayed substantial levels of genetic differentiation (overall FST = 0.067, RST = 0.091) and STRUCTURE identified eight distinct clusters. The significant regional variation was demonstrated in both genetic diversity and population structure, most notably between Arctic and Pacific basins. On a regional scale, contrasting patterns were revealed with limited gene flow between populations of the Arctic region (FST = 0.117) and high gene flow between the Bering Sea (FST = 0.017) or Sea of Okhotsk (FST = 0.031), which were probably associated with differences in larval distribution from the spawning grounds due to different oceanographic conditions of the studied areas. These results demonstrate the effect of local contemporary forces in shaping different patterns of genetic connectivity and diversity within O. dentex.