The negative correlation between somatic aneuploidy and growth in the oyster Crassostrea gigas and implications for the effects of induced polyploidization

Abstract

This study extends previous observations that chromosome loss in somatic cells of juveniles of the pacific oyster Crassostrea gigas is associated with reduced growth rate. All four studies designed to examine this association (two using random population samples and two using full sibs) produced the same result. This consistent effect appears to be unrelated with the commonly, but not consistently, observed correlation between degree of allozyme heterozygosity and growth. We propose that the inverse relationship between aneuploidy and growth is due to the unmasking of deleterious recessive genes caused by 'progressive haploidization' of somatic cells. Because unmasking of deleterious recessive genes by random chromosome loss is unlikely in polyploid cells, this hypothesis may also provide an explanation for the observation that artificially produced polyploid shellfish usually grow at faster rates than normal diploid ones.