Coexistence of self-compatible and self-incompatible alleles in a plant metapopulation via spatial rock-paper-scissors dynamics

Abstract

Around 40% of flowering plants exhibit a preference for self-incompatibility systems (SI) on a macro-evolutionary scale. The dynamics of SI and self-compatible systems (SC) alleles can lead to the fixation of one genotype or coexistence, depending on factors like inbreeding depression and initial fractions. For the first time, we explore the dynamics of self-incompatible (SI) and self-compatible (SC) alleles in the presence of competitors, studying the relationship between population structure and SI frequency. Our numerical simulations consider non-instantaneous coupling between patches, focusing on a regime where the competitor’s fitness falls between inbred and outbred fitness. In this regime, SI, SC, and competitors exhibit repeating cycles of rock-paper-scissors dynamics both spatially and temporally. We find well-mixed environment leads to lower fractional population density of the focal species. Additionally in this regime, a paradoxical result emerges: in stress-free regions favorable to SI, the focal species may lose to the competitor.