Pollination Fluctuations Drive Evolutionary Syndromes Linking Dispersal and Mating System

The existence of a syndrome linking dispersal rate and mating system has long been debated in evolutionary ecology, especially in plants. Some verbal models hypothesize that the ability to self-fertilize may be associated with high dispersal, since completely outcrossing species cannot reproduce when they disperse to an empty destination site. However, empirical observations fail to support a clear trend, and an association of high colonizing ability with high outcrossing has been reported. Here we develop a general metapopulation model for the joint evolution of seed dispersal and self-fertilization when local pollen limitation varies stochastically over time. Under these assumptions, we study how dispersal and mating system influence each other through selection. We predict the existence of two consistent syndromes of traits: dispersing outcrossers and nondispersing (partial) selfers. These theoretical expectations contradict the classical view and shed new light on an old problem, allowing us to reinterpret empirical data. Finally, our predictions are discussed in light of empirical data concerning the association of seed dispersal mechanism and breeding system.