Data from: Transmission advantage favors selfing allele in experimental populations of self-incompatible Witheringia solanacea (Solanaceae)

The evolution of self-fertilization is one of the most commonly traversed
transitions in flowering plants, with profound implications for population
genetic structure and evolutionary potential. We investigated factors
influencing this transition using Witheringia solanacea, a predominantly
self-incompatible (SI) species within which self-compatible (SC) genotypes
have been identified. We showed that self-compatibility in this species
segregates with variation at the S-locus as inherited by plants in F1 and
F2 generations. To examine reproductive assurance and the transmission
advantage of selfing, we placed SC and SI genotypes in genetically
replicated gardens and monitored male and female reproductive success, as
well as selfing rates of SC plants. Self-compatibility did not lead to
increased fruit or seed set, even under conditions of pollinator scarcity,
and the realized selfing rate of SC plants was less than 10%. SC plants
had higher fruit abortion rates, consistent with previous evidence showing
strong inbreeding depression at the embryonic stage. Although the selfing
allele did not provide reproductive assurance under observed conditions,
it also did not cause pollen discounting, so the transmission advantage of
selfing should promote its spread. Given observed numbers of S-alleles and
selfing rates, self-compatibility should spread even under conditions of
exceedingly high initial inbreeding depression.