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Original article (peer-reviewed)

Journal Journal of Evolutionary Biology
Page(s) 1
Title of proceedings Journal of Evolutionary Biology
DOI 10.1111/jeb.12219


The evolution of self-compatibility (SC) by the loss of self-incompatibility (SI) is regarded as one of the most frequent transitions in flowering plants. SI systems are generally characterized by specific interactions between the male and female specificity genes encoded at the S-locus. Recent empirical studies have revealed that the evolution of SC is often driven by male SC- conferring mutations at the S-locus rather than by female mutations. In this study, using a forward simulation model, we compared the fixation proba- bilities of male vs. female SC-conferring mutations at the S-locus. We explic- itly considered the effects of pollen availability in the population and bias in the occurrence of SC-conferring mutations on the male and female specific- ity genes. We found that male SC-conferring mutations were indeed more likely to be fixed than were female SC-conferring mutations in a wide range of parameters. This pattern was particularly strong when pollen availability was relatively high. Under such a condition, even if the occurrence of muta- tions was biased strongly towards the female specificity gene, male SC- conferring mutations were much more often fixed. Our study demonstrates that fixation probabilities of those two types of mutation vary strongly depending on ecological and genetic conditions, although both types result in the same evolutionary consequence—the loss of SI.