Microsatellite Genotypes Reveal Some Long-Distance Gene Flow inPerkinsus marinus, a Major Pathogen of the Eastern Oyster,Crassostrea virginica(Gmelin)

Abstract

ABSTRACT As the agent of Dermo disease, Perkinsus marinus causes significant mortality and reduced fecundity its eastern oyster host, Crassostrea virginica. Passive dispersal of P. marinus between hosts subjects parasite movements to control by water currents in estuarine systems, potentially limiting connectivity among parasite populations in different estuaries. Given recent evidence for sexual reproduction in P. marinus, estimates of gene flow among locations may provide insights into this parasite's epidemiology. In this study, 1,082 wild oysters were collected from 2002 to 2008 at 15 geographical locations encompassing 4,800 km of the Gulf of Mexico and Atlantic coasts of the United States. Of these, 742 oysters (68.9% prevalence) were determined to be infected by P. marinus. Among infected oysters, 374 were determined to be infected by a single parasite genotype based on amplification of seven microsatellite loci, and therefore were amenable to analysis. Allele frequencies differed significantly amo...