Perenniality induces high inbreeding depression in self-fertilising species

When predicting the fate and consequences of recurring deleterious mutationsin self-fertilising populations most models developed make the assumptionthat populations have discrete non-overlapping generations. This makesthem biologically irrelevant when considering perennial species with overlappinggenerations and where mating occurs independently of the age group.The few models studying the effect of perennial life-histories on the geneticproperties of populations in the presence of self-fertilisation have done soconsidering age-dependent selection. They find low levels of inbreeding depressionin perennial populations that do not explain empirical observations.Here we propose a simple deterministic model in continuous time with selectionat different fitness traits and feedback between population fitnessand size. We find that a perennial life-history can result in high levels ofinbreeding depression in spite of inbreeding, due to higher frequencies of heterozygousindividuals at the adult stage. We also propose that there may bedemographic advantages for self-fertilisation that are independent of reproductivesuccess