Intraspecific variation in the 16S ribosomal gene of Crassostrea virginica

Population structure was examined in Crassostrea virginica from Pamlico Sound, North Carolina, and Chesapeake Bay, Virginia, on the Atlantic Coast and Galveston Bay, Texas, in the Gulf of Mexico. Haplotypes were identified by digesting with 10 restriction enzymes a 560-bp fragment of the mitochondrial 16S ribosomal gene amplified by polymerase chain reaction (PCR). Restriction fragment profiles disclosed few differences: most C. virginica were the same haplotype, and 10 other rare haplotypes showed no population or geographic structuring. As previous studies had established that little gene flow occurs between C, virginica on the Atlantic Coast and the Gulf of Mexico, it was concluded that functional constraints have prevented divergence in the restriction fragment sites of the 16S ribosomal gene