Evolution of Selfing: Recurrent Patterns in Molecular Adaptation

Selling has evolved in animals, fungi, and plants, and since Darwin's pioneering study, it is considered one of the most frequent evolutionary trends in flowering plants. Generally, the evolution of selling is characterized by a loss of self-incompatibility, the selfing syndrome, and changes in genome-wide polymorphism patterns. Recent interdisciplinary studies involving molecular functional experiments, genome-wide data, experimental evolution, and evolutionary ecology using Arabidopsis thaliana, Caenorbabditis elegans, and other species show that the evolution of selfing is not merely a degradation of crossing traits but a model for studying the recurrent patterns underlying adaptive molecular evolution. For example, in wild Arabidopsis relatives, self-compatibility evolved from mutations in the male specificity gene S.-LOCUS CYSTELNE-RICH PROTETN/S-LOCUS PROTEIN 11 (VS/VM, rather than the female specificity gene, S-LOUS' RECEPTOR KINASE (SRK), supporting the theoretical prediction of sexual asymmetry. Prevalence of dominant self-compatible mutations is consistent with Haldane's sieve, which acts against recessive adaptive mutations. Time estimates based on genome-wide polymorph isms and self-incompatibility genes generally support the recent origin of selling.