Inbreeding depression maintained by recessive lethal mutations interacting with stabilizing selection on quantitative characters in a partially self-fertilizing population.
The bimodal distribution of fitness effects of new mutations and standing genetic variation, due to early-acting strongly deleterious recessive mutations and late-acting mildly deleterious mutations, is analyzed using the Kondrashov model for lethals (K), with either the infinitesimal model for selfing (IMS) or the Gaussian allele model (GAM) for quantitative genetic variance under stabilizing selection. In the combined models (KIMS and KGAM) high genomic mutation rates to lethals and weak stabilizing selection on many characters create strong interactions between early and late inbreeding depression, by changing the distribution of lineages selfed consecutively for different numbers of generations. Alternative stable equilibria can exist at intermediate selfing rates for a given set of parameters. Evolution of quantitative genetic variance under multivariate stabilizing selection can strongly influence the purging of nearly recessive lethals, and sometimes vice versa. If the selfing rate at the purging threshold for quantitative genetic variance in IMS or GAM alone exceeds that for nearly recessive lethals in K alone, then in KIMS and KGAM stabilizing selection causes selective interference with purging of lethals, increasing the mean number of lethals compared to K; otherwise, stabilizing selection causes selective facilitation in purging of lethals, decreasing the mean number of lethals.
Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, United Kingdom.|Current Address: Center for Biodiversity Dynamics, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
Russell
R
Lande
Centre d'Ecologie et des Sciences de la Conservation, Sorbonne Universités UMR MNHN-CNRS-UPMC 7204, 75005, Paris, France.
Emmanuelle
E
Porcher
D003241:Consanguinity; D014644:Genetic Variation; D000071422:Inbreeding Depression; D008957:Models, Genetic; D009154:Mutation; D012641:Selection, Genetic
Alternative equilibria; inbreeding coefficient; inbreeding depression; purging threshold; selective facilitation; selective interference