Genetic structure of summer flounder (Paralichthys dentatus) populations north and south of Cape Hatteras

Genetic divergence among samples of summer flounder (Paralichthys dentatus, Linnaeus) was estimated to evaluate the effect of Cape Hatteras, a well-kn own zoogeographic barrier in the western Atlantic Ocean, on intraspecific g ene flow. Previous studies based on meristic and morphometric variation and tagging data suggested that gene flow might be limited among summer flound er populations north and south of Cape Hatteras, although the high vagility of both juveniles and adults suggests otherwise. We analyzed genetic diver sity revealed in the mitochondrial DNA (mtDNA) control region in samples of juveniles and adults collected in 1992 to 1995 from coastal sites from Buz zard's Bay, Massachusetts to Charleston, South Carolina. In contrast to pre vious morphological studies, analyses of mtDNA variation reveal no signific ant population subdivision centered around Cape Hatteras.