LOSS OF GAMETOPHYTIC SELF-INCOMPATIBILITY WITH EVOLUTION OF INBREEDING DEPRESSION

Abstract : Gametophytic self-incompatibility (SI) in plants is a widespread mechanism preventing self-fertilization and the ensuing inbreeding depression, but it often evolves to self-compatibility. We analyze genetic mechanisms for the breakdown of gametophytic SI, incorporating a dynamic model for the evolution of inbreeding depression allowing for partial purging of nearly recessive lethal mutations by selfing, and accounting for pollen limitation and sheltered load linked to the S-locus. We consider two mechanisms for the breakdown of gametophytic SI: a nonfunctional S-allele and an unlinked modifier locus that inactivates the S-locus. We show that, under a wide range of conditions, self-compatible alleles can invade a self-incompatible population. Conditions for invasion are always less stringent for a nonfunctional S-allele than for a modifier locus. The spread of self-compatible genotypes is favored by extremely high or low selfing rates, a small number of S-alleles, and pollen limitation. Observed parameter values suggest that the maintenance of gametophytic SI is caused by a combination of high inbreeding depression in self-incompatible populations coupled with intermediate selfing rates of the self-compatible genotypes and sheltered load linked to the S-locus.
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Emmanuelle Porcher, Russell Lande. LOSS OF GAMETOPHYTIC SELF-INCOMPATIBILITY WITH EVOLUTION OF INBREEDING DEPRESSION. Evolution, Wiley, 2005, 59, pp.46 - 60. ⟨10.1111/j.0014-3820.2005.tb00893.x⟩. ⟨mnhn-02265362⟩

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