Lj. English et al., Genetic variation of wild and hatchery populations of the Pacific oyster, Crassostrea gigas (Thunberg), in Australia, AQUACULTURE, 187(3-4), 2000, pp. 283-298
Pacific oysters were introduced to Tasmania about 50 years ago from Japan;
fears had been expressed that they would have lost genetic variation during
their subsequent naturalisation. Using 17 allozyme loci, three hatchery an
d four naturalised populations of Crassostrea gigas (Thunberg) in Australia
were compared with one another and with two endemic Japanese populations.
All populations showed a high degree of genetic variability. The percent of
polymorphic loci ranged from an average of 70.6% (hatcheries) through 73.5
% (naturalised and Japan). Mean observed heterozygosities ranged from 0.267
(naturalised) through 0.285 (hatcheries) to 0.291 (Japan). Mean numbers of
alleles per locus ranged from 3.0 (hatcheries) through 3.3 (naturalised) t
o 3.5 (Japan). Most loci and populations showed good fits to Hardy-Weinberg
expectations; the few significant exceptions were heterozygote deficiencie
s. Allele-frequency differences among populations were minor, although some
times statistically significant: only about 1% of the allele frequency vari
ation could be attributed to among-population differences. The introduced o
ysters appear to have retained most of the genetic variation present in the
Japanese populations. (C) 2000 Elsevier Science B.V. All rights reserved.