Estimating the Effect of Phenological Mismatch on the Success of Assisted Gene Flow

Adaptation to changing environmental conditions and subsequent recovery in population growth through evolutionary rescue is critical for many declining species, but it relies on populations having sufficient genetic variation. Assisted gene flow provides a solution to low genetic variance by introducing gene flow between distinct populations, allowing evolutionary rescue to proceed. Assisted gene flow, however, requires that these populations can interbreed. Many populations are divergent in reproductive phenology, reducing hybridization rates. The potential for hybridization between plant populations can be estimated from flowering schedules, but for these estimates to be useful they must be proven accurate. In a pair of two-generation experiments, I compared prospective estimates of hybridization, derived from flowering schedules, to retrospective estimates, derived from an analysis of offspring, using flowering time as a genetic marker. In both cases, hybridization was asymmetric. The prospective and retrospective strongly agreed under controlled pollination conditions, but less so under natural pollination in the field.M.Sc