A note on selection differential and generation length when generations overlap

Abstract

SUMMARYThe generation interval may be defined as the mean age of parents of all progeny born, or as the mean age of parents of only those progeny destined to be selected as replacements. If the mean age of parents of replacements is used, selection differentials must be calculated within parental age groups. If the mean age of parents of all progeny born is used, the selection differential contains a component due to disproportionate selection of replacements from different parental age groups.