TY - JOUR
T1 - Heterozygosity and body size in triploid Pacific oysters, Crassostrea gigas Thunberg, produced from meiosis II inhibition and tetraploids
AU - Wang, Zhaoping
AU - Guo, Ximing
AU - Allen, Standish K.
AU - Wang, Rucai
PY - 2002/2/11
Y1 - 2002/2/11
N2 - Triploid molluscs grow significantly faster than diploids in most species studied so far, a phenomenon that has been referred to as triploid gigantism. Three hypotheses have been proposed, attributing triploid gigantism to sterility, increased heterozygosity, or cell size. Testing the heterozygosity hypothesis, the authors measured the body size and allozyme heterozygosity in three replicates of a normal diploid group (2n), an induced triploid group (3nCB) and a mated triploid group produced from diploid × tetraploid mating (3nDT). Body size measurements at 1 year of age showed that both 3nDT and 3nCB triploids were significantly bigger than normal diploids, by 26% and 14%, respectively, in meat weight. The 3nDT triploids were 10% bigger than the 3nCB triploids, although the difference was not statistically significant. Heterozygosity at five polymorphic loci averaged 0.48 for 3nCB and 0.57 for 3nDT triploids, which were 37% and 63% higher, respectively, than that for normal diploids (0.35). Differences in heterozygosity were highly significant among all three groups. Among the three groups, there was a strong and positive correlation between meat weight and heterozygosity. The correlation was weak or undetectable within groups or at the individual level. These results support the heterozygosity hypothesis, but do not negate the cell size and sterility hypotheses. It is possible that the cell size is the fundamental cause for triploid gigantism, which is better expressed in 3nDT (than 3nCB) triploids because of further increases in heterozygosity or other genetic factors.
AB - Triploid molluscs grow significantly faster than diploids in most species studied so far, a phenomenon that has been referred to as triploid gigantism. Three hypotheses have been proposed, attributing triploid gigantism to sterility, increased heterozygosity, or cell size. Testing the heterozygosity hypothesis, the authors measured the body size and allozyme heterozygosity in three replicates of a normal diploid group (2n), an induced triploid group (3nCB) and a mated triploid group produced from diploid × tetraploid mating (3nDT). Body size measurements at 1 year of age showed that both 3nDT and 3nCB triploids were significantly bigger than normal diploids, by 26% and 14%, respectively, in meat weight. The 3nDT triploids were 10% bigger than the 3nCB triploids, although the difference was not statistically significant. Heterozygosity at five polymorphic loci averaged 0.48 for 3nCB and 0.57 for 3nDT triploids, which were 37% and 63% higher, respectively, than that for normal diploids (0.35). Differences in heterozygosity were highly significant among all three groups. Among the three groups, there was a strong and positive correlation between meat weight and heterozygosity. The correlation was weak or undetectable within groups or at the individual level. These results support the heterozygosity hypothesis, but do not negate the cell size and sterility hypotheses. It is possible that the cell size is the fundamental cause for triploid gigantism, which is better expressed in 3nDT (than 3nCB) triploids because of further increases in heterozygosity or other genetic factors.
KW - Aquaculture
KW - Crassostrea gigas
KW - Growth
KW - Heterozygosity
KW - Triploidy
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U2 - 10.1016/S0044-8486(01)00845-6
DO - 10.1016/S0044-8486(01)00845-6
M3 - Article
AN - SCOPUS:0037060158
SN - 0044-8486
VL - 204
SP - 337
EP - 348
JO - Aquaculture
JF - Aquaculture
IS - 3-4
ER -