title: On the Consequences of Purging and Linkage on Fitness and Genetic Diversity.
abstract: Using computer simulation we explore the consequences of linkage on the inbreeding load of an equilibrium population, and on the efficiency of purging and the loss of genetic diversity after a reduction in population size. We find that linkage tends to cause increased inbreeding load due to the build up of coupling groups of (partially) recessive deleterious alleles. It also induces associative overdominance at neutral sites but rarely causes increased neutral genetic diversity in equilibrium populations. After a reduction in population size, linkage can cause some delay both for the expression of the inbreeding load and the corresponding purging. However, reasonable predictions can be obtained for the evolution of fitness under inbreeding and purging by using empirical estimates of the inbreeding depression rate. Purging selection against homozygotes for deleterious alleles affects the population's pedigree. Furthermore, it can slow the loss of genetic diversity compared to that expected from the variance of gametic contributions to the breeding group and even from pedigree inbreeding. Under some conditions, this can lead to a smaller loss of genetic diversity, even below that expected from population size in the absence of selection.
authors.affiliation: Departamento de Genética, Facultad de Biología, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Bersabé
authors.affiliation: Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, 36310 Vigo (Pontevedra), Spain.
authors.forename: Armando
authors.initials: A
authors.lastname: Caballero
authors.affiliation: Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, 36310 Vigo (Pontevedra), Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Pérez-Figueroa
authors.affiliation: Departamento de Genética, Facultad de Biología, Universidad Complutense, 28040 Madrid, Spain augardo@ucm.es.
authors.forename: Aurora
authors.initials: A
authors.lastname: García-Dorado
mesh_terms: D000465:Algorithms; D000483:Alleles; D003198:Computer Simulation; D019143:Evolution, Molecular; D056084:Genetic Fitness; D008040:Genetic Linkage; D014644:Genetic Variation; D005828:Genetics, Population; D007178:Inbreeding; D008957:Models, Genetic; D009154:Mutation; D011995:Recombination, Genetic; D012641:Selection, Genetic
keywords: associative overdominance; genetic diversity; inbreeding depression; inbreeding load