MORPHOLOGICAL-VARIATION AND GENETIC-VARIATION AMONG 3 POPULATIONS OF CALICO SCALLOPS, ARGOPECTEN-GIBBUS

We surveyed morphological and genetic variation among three population s of Argopecten gibbus from the Marquesas Keys, Florida; Cape Canavera l, Florida; and Cape Lookout, North Carolina; in order to determine th e extent of the genetic isolation of these populations and to examine the hypothesis for larval transport between populations. Burnaby size- adjusted principal component analysis of 14 morphological characters r evealed significant differences among sites for the third principle co mponent, which explained 6% of the total variation. Analyses of electr ophoretic loci showed significant allele frequency heterogeneity among sites for one of seven polymorphic loci. The magnitude of the morphol ogical and genetic differences between the Marquesas Keys sample and b oth of the Atlantic coast samples was generally greater than between t he geographically more distant Cape Canaveral and Cape Lookout samples , although overall levels of variation among sites were small. Estimat es of gene flow suggest that relatively frequent migration, sufficient for panmixia in the absence of historical divergence, may occur betwe en populations. Our results suggest that oceanographic processes play a critical role in the transport of A. gibbus larvae between populatio ns. We recommend that management of the A. gibbus fishery should inclu de consideration of these processes.