Absence of genetic differentiation among geographically close sea scallop (Placopecten magellanicus G.) Beds with CDNA and microsatellite markers

This study examined the extent of genetic differentiation between two geographically close beds (shallow and deep) of sea scallop (Placopecten magellanicus Gmelin) from Sunnyside, Trinity Bay, Newfoundland, with cDNA probes and microsatellite markers. Scallops from the deep bed had been shown to display lower oxygen consumption, higher filtration rate, and lower somatic and gamete production in situ than did scallops from the shallow bed, but differences in filtration rate were no longer found after laboratory acclimation. With three cDNA probes and three microsatellite markers, no genetic differences were found between the shallow and deep scallops collected in 1991, 1992, or 1994. This study suggests that the physiological differences observed in situ between these scallop beds appear to be mainly related to less favorable environmental conditions associated with deeper water rather than the result of genetic differentiation. The use of genetic markers allowed us to clarify the level of differentiation between physiologically distinct but proximate beds of sea scallops.