Genetic heterogeneity, detected by PCR-SSCP, among samples of larval Pacific oysters ( Crassostrea gigas ) supports the hypothesis of large variance in reproductive success

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Li, Gang, Hedgecock, Dennis
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1998
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Pacific; Crassostrea gigas
• Online Access: http://dx.doi.org/10.1139/f97-312; http://www.nrcresearchpress.com/doi/pdf/10.1139/f97-312

Differences in genetic composition among samples of larvae produced during a single spawning season by a semi-isolated population of Pacific oysters (Crassostrea gigas) in Dabob Bay, Washington, confirm a specific prediction of the hypothesis that this and other marine animals have large variances in reproductive success. To study the genetics of single larvae, we cloned and sequenced part of the mitochondrial genome and developed polymerase chain reaction (PCR) primers to amplify four segments totaling nearly 2300 base pairs, or 13% of the genome. PCR products were digested with restriction enzymes into smaller fragments, which were then screened for single-strand conformational polymorphisms (SSCP). Seven plankton samples (total N = 877), taken between 10 and 21 August 1993, showed a common composite PCR-SSCP haplotype that comprised from 53 to 85% of samples. Nevertheless, exact probability and permutation tests reveal that early and late samples from north Dabob Bay differed significantly from the rest. These differences cannot be ascribed to spatial variation and are consistent with the hypothesis that larvae are produced by relatively few adults, in accord with previous observations of substantial genetic drift in this large population.