Genetic and morphometric differentiation between populations of the cupped oyster Crassostrea gigas

AVACA, M S.; NARVARTE M.A; HEUTERBISE S.; ROCHE M.A.; CORNETTE F.; LAPEGUE S.

Congreso; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

The Pacific cupped oyster, Crassostrea gigas, is one of the most common cultivated aquatic species. Because of its tolerance to wide ranges of salinity and temperature, this species has been introduced into many countries where it invaded and has become naturalized. In this study, we investigated whether the naturalized populations of C. gigas recently detected (Los Pocitos, 40°26´S/62° 25’W; El Cóndor, 41°03´S/62° 49’W) are genetically and morphometrically similar to those firstly found at San Blas (40°40´S/62°10’W). Oysters were studied by using four microsatellite markers (CG49, CG108, L10 and AMY) and several classic morphometric measures (shell height, length and width, and total weight). Genotyping of 55 oysters from the three populations revealed 30 to 43 alleles per locus. San Blas population presented a larger number of alleles - for almost all loci (except L10) - than populations of El Cóndor and Los Pocitos. No significant genetic differentiation was found between populations when only those loci found in Hardy - Weinberg equilibrium were used in FST estimation (L10, AMY; p > 0.05). Different morphometric relationships between shell variables were found at each population. Genetic similarity between populations suggests a common origin or the existence of high flow among them, and evidences the great dispersal capacity known for this species. Morphometric differences are probably due to the plastic growth patterns typically shown by these animals, which result in a wide range of ecophenotypic variants.