On the evolution of genetic incompatibility systems. II. Initial increase of strong gametophytic self-incompatibility under partial selfing and half-sib mating

This study addresses the origin of gametophytic self-incompatibility in populations undergoing a mixture of random outcrossing, sib mating, and selfing. The effect of the incompatibility system on the genotypic distribution among offspring derived from the 3 pollen sources are described. The total change in average additive genotypic value is partitioned into components reflecting trade-offs in offspring number, parent-offspring relatedness, and gametic selection. The conditions for the initial increase of a self-incompatibility allele with full activity are presented under the assumptions of complete dominance and complete recessivity of stylar expression. Low rates of inbreeding and recessivity of stylar expression of the incompatibility reaction promote the introduction of gametophytic self-incompatibility. Findings are assessed with respect to the hypothesis that incompatibility systems function as a means of regulating outcrossing distance as well as avoiding self-fertilization. Empirical evidence concerning recessivity in the stylar rejection reaction is reviewed and the response of inbreeding depression to the introduction of self-incompatibility is discussed. -from Author

Duke Scholars

Author Marcy K. Uyenoyama Biology