Throughout the biosphere, most organisms display some sort of adaptation to reduce inbreeding. In flowering plants alone, there are a staggering number of adaptations that prevent inbreeding, yet these systems break down frequently. Mutations causing self-pollination should enjoy two major selective advantages. Mutations causing self-pollination will spread in nature either because they enjoy a gene-level transmission advantage or because they boost seed production when pollination is uncertain. No study has simultaneously tested these mechanisms and evaluated their interaction, so it is not well understood why outcross-pollination mechanisms repeatedly break down. In this project, a mutation causing self-pollination will be crossed into a typically outcross-pollinated genome and replicated field experiments will examine whether this mutation spreads because of genetic or ecological reasons. This project will identify the mechanisms that cause evolutionary shifts to inbreeding, which imperil plant biodiversity. The project will train undergraduate and graduate students to use genetic markers to infer parentage and patterns of gene flow, which are critical tools in applied agricultural settings. Students will present their results at public outreach events coordinated by the Center for Cedar Glades Studies (CCGS) in Tennessee. The involvement of students in the process of direct outreach will communicate the principles of evolution and conservation biology to the public. The PIs will also work with science educators at the CCGS to develop a pollination ecology field exercise aimed at K-12 students to be included in the "Cedar Glades Activity Guide" published by the CCGS and used by many local science teachers.