Genealogy-dependent variation in viability among self-incompatibility genotypes.
Many hermaphroditic plants avoid self-fertilization by rejecting pollen that express genetically determined specificities in common with the pistil. The S-locus, comprising the determinants of pistil and pollen specificity, typically shows extremely high polymorphism, with dozens to hundreds of specificities maintained within species. This article explores a conjecture, motivated by empirical findings, that the expression of recessive deleterious factors at sites closely linked to the S-locus may cause greater declines in the viability of zygotes constituted from more closely related S-alleles. Diffusion approximation models incorporating variation in viability among S-locus genotypes and antagonistic interactions between a new specificity and its immediate parent specificity are constructed and analyzed. Results indicate that variation in viability tends to reduce the number of specificities maintained in a population at stochastic steady state, and that genealogy-based antagonism reduces the rate of bifurcation of S-allele lineages. These effects may account for some of the unusual features observed in empirical studies of S-allele genealogies.
Department of Biology, Box 90338, 107 Bio Sci. Building, Duke University, Durham, NC 27708-0338, USA. marcy@duke.edu
Marcy K
MK
Uyenoyama
D000483:Alleles; D005838:Genotype; D008957:Models, Genetic; D018521:Plant Physiological Phenomena; D010944:Plants / Q000235:genetics*