Modelling problems in conservation genetics using Drosophila: Consequences of Harems

Abstract

Polygamous mating systems occur in most mammals and some birds. They are predicted to reduce effective population sizes and to increase inbreeding and loss of genetic variation. To evaluate this theory experimentally, ten replicate lines of a Harem treatment with seven females and one male and nine replicate lines of an equal sex ratio (ESR) treatment with four pairs of parents per generation were maintained for eight generations. Equalization of family sizes was used in both treatments. Loss in average gene diversity was greater in harems than ESR (0·165 v 0·063), the effective population size lower (6·6 v 13·9), and the relative reproductive fitness lower (0·21 v 0·46). Harem mating structures should be avoided or circumvented wherever possible in the management of captive populations.