Genetics of Zoarces populations

The Kaloe population of Zoarces viviparus was sampled in two successive winters for males, pregnant and non-pregnant females, and the EstIII genotypes of the fish, including mother-offspring combinations, were scored. The observations were submitted to a selection component analysis which revealed significant evidence of a change in genotypic structure that occurs in the period between the foetal and the adult stage. It is argued that this genotypic distortion, which leads to a gene frequency shift, is most likely due to zygotic selection through either differential survival or differential emigration. The observations indicate that the zygotic gene frequency shift is counteracted by either male sexual or male gametic selection, but there is no statistically significant proof of this contention.