Selection of sporophytic and gametophytic self-incompatibility in the absence of a superlocus.
Self-incompatibility (SI) is a complex trait that enforces outcrossing in plant populations. SI generally involves tight linkage of genes coding for the proteins that underlie self-pollen detection and pollen identity specification. Here, we develop two-locus genetic models to address the question of whether sporophytic SI (SSI) and gametophytic SI (GSI) can invade populations of self-compatible plants when there is no linkage or weak linkage of the underlying pollen detection and identity genes (i.e., no S-locus supergene). The models assume that SI evolves as a result of exaptation of genes formerly involved in functions other than SI. Model analysis reveals that SSI and GSI can invade populations even when the underlying genes are loosely linked, provided that inbreeding depression and selfing rate are sufficiently high. Reducing recombination between these genes makes conditions for invasion more lenient. These results can help account for multiple, independent evolution of SI systems as seems to have occurred in the angiosperms.
Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada. Daniel.Schoen@mcgill.ca.
Daniel J
DJ
Schoen
Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada.
Megan J
MJ
Roda
D005075:Biological Evolution; D008040:Genetic Linkage; D055993:Germ Cells, Plant / Q000502:physiology; D019684:Magnoliopsida / Q000235:genetics / Q000502:physiology*; D008957:Models, Genetic; D054817:Pollination; D057945:Self-Fertilization