Oceanographic barriers to gene flow promote genetic subdivision of the tunicate in a North Sea archipelago.

Pelagic larval development has the potential to connect populations over large geographic distances and prevent genetic structuring. The solitary tunicate has pelagic eggs and a swimming larval stage lasting for maximum a few days, with the potential for a homogenizing gene flow over relatively large areas. In the eastern North Sea, it is found in a geomorphologically complex archipelago with a mix of fjords and open costal habitats.

Population structure in Atlantic cod in the eastern North Sea-Skagerrak-Kattegat: early life stage dispersal and adult migration.

Background: In marine fish species, where pelagic egg and larvae drift with ocean currents, population structure has been suggested to be maintained by larval retention due to hydrographic structuring and by homing of adult fish to natal areas. Whilst natal homing of adults has been demonstrated for anadromous and coral reef fishes, there are few documented examples of philopatric migration in temperate marine fish species.

Results: Here, we demonstrate temporally stable genetic differentiation among spawning populations of Atlantic cod (Gadus morhua L.

Development of 10 microsatellite loci in the ling (Molva molva).

We developed primers for two dinucleotide and eight tetranucleotide microsatellite loci in a marine fish, the ling (Molva molva). All markers were obtained from partial genomic DNA libraries and characterized in 55 unrelated individuals from one putative population. The number of alleles ranged from five to 24 (average 10.