Components of fitness and the pgi polymorphism in the freshwater isopod asellus aquaticus (L.) 2. zygotic selection

Abstract

A 2[Symbol found] year study of PGI genotypes in a population of the isopod Asellus aquaticus showed consistent seasonal changes in genotype frequencies. In June and July the frequency of the 3/4 heterozygote increased from 0·1–0·25 while the frequency of the 2/3 heterozygote decreased from 0·15–0·05. Laboratory and field experiments demonstrated that this was due too differential mortality among juveniles, low oxygen concentration being the selective agent. © 1987 The Genetical Society of Great Britain.