Model of genome renewal. This model applies to wine yeast which are mostly homothallic. Mutations cause recessive heterozygosities which are expressed when the diploid cells sporulate and diploidize through homothallic switching. (A). Two loci are considered,SUC and A. In the first cycle, one SUCallele mutates to suc, which becomes suc/suc. In the next cycle, A mutates to a, which becomesa/a. (B). Genome renewal also can eliminate deleterious mutations.