A search for gametic disequilibrium in the plaice, Pleuronectes platessa

Abstract

Large samples of a natural population of the plaice were examined for evidence of gametic disequilibrium (D) at five and seven polymorphic enzyme loci (younger and older fish respectively). A single pairwise locus comprison gave a statistically significant value for D: Gpdh-1 and Pgi-2 in young fish. The mean D values of the 10 pairwise comparisons of the five loci in young and old fish were low, 0.00175 and 0.00420 respectively: corresponding values of R (the correlation of gene frequencies) were 0.01473 and 0.03002. The increase in these parameters in older fish might be due either to population admixture, natural selection, a smaller sample size, or to a combination of these factors. The mean D and R values for the 21 pairwise comparisons of the seven loci typed in older fish were 0.00394 and 0.2496 respectively. Two loci catalysing adjacent steps in the glycolytic pathway, Pgm-1 and Pgi-2, showed no evidence of epistatic interactions generating disequilibrium.