CRYPTIC SELF-INCOMPATIBILITY AND THE BREEDING SYSTEM OF CLARKIA UNGUICULATA (ONAGRACEAE)

Analysis of 2,117 segregating progeny from competitive pollinations involving self and foreign pollen reveals that Clarkia unguiculata possesses a cryptic self-incompatibility mechanism. This mechanism promotes outcrossing when foreign pollen is available, yet allows for high fecundity through selling in marginal or catastrophically reduced populations. Competitively based self-incompatibility in the species suggests that discrimination against genetically similar siblings may also be possible. The preferential self-exclusion system insures that a seed crop of maximal size and genetic heterogeneity will be produced despite unpredictable environmental perturbations.