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LOSS OF GAMETOPHYTIC SELF‐INCOMPATIBILITY WITH EVOLUTION OF INBREEDING DEPRESSION
Author(s) -
Porcher Emmanuelle,
Lande Russell
Publication year - 2005
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2005.tb00893.x
Subject(s) - selfing , inbreeding depression , biology , genetic load , inbreeding , locus (genetics) , genetics , allele , population , genotype , pollen , evolutionary biology , ecology , gene , demography , sociology
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.