Allozymic variation in the Pacific oyster Crassostrea gigas from San Quintín Bay,Baja California, Mexico

Abstract

Allozymic variability was analyzed in adult oysters Crassostrea gigas from the 1999, 2000 and 2001 crops of San Quintín Bay, Baja California, Mexico, using starch gel electrophoresis. The analysis included 13 enzymatic systems that revealed 25 loci, of which 16 were monomorphic and 9 were polymorphic. The values of observed heterozygosis ranged from 0.01 to 0.04, while according to the literature, the value for wild oysters is approximately 0.20. The results indicate that there are no statistical differences in the allozymic variability among the annual populations analyzed; however, the χ2 test revealed that in the three years, the oyster populations did not present an equilibrium with regard to the Hardy-Weinberg theoretical model. The three populations showed a reduced genetic diversity due to inbreeding and the bottleneck effect.