Gametophytic Self‐fertilization in Homosporous Plants: Development, Evaluation, and Application of a Statistical Method for Evaluating Its Importance

The methods described here make it possible to use data on sporophytic genotype frequencies to estimate the frequency of gametophytic self‐fertilization in populations of homosporous plants. Bootstrap bias reduction is effective in reducing or eliminating the bias of the maximum likelihood estimate of the gametophytic selfing rate. The bias‐corrected percentile method provides the most reliable confidence intervals for allele frequencies. The percentile method gives the most reliable confidence intervals for the gametophytic selfing rate when selfing is common. The maximum likelihood intervals, the percentile intervals, the bias‐corrected percentile intervals, and the bootstrap t intervals are all overly conservative in their construction of confidence intervals for the gametophytic selfing rate when self‐fertilization is rare. Application of the recommended methods indicates that gametophytic self‐fertilization is quite rare in two sexually reproducing populations of Pellaea andromedifolia studied by Gastony and Gottlieb (1985).