Eco-Evolutionary Feedbacks Between Predator’s Linkage Disequilibrium and Prey Densities Maintain Diversity

Diversity occurs at multiple scales. Within a single population, there is diversity in genotypes and phenotypes. At a larger scale, within ecological communities, there is diversity in species. There have been a number of studies to investigate how diversity at these two scales influence each other through what has been termed eco-evolutionary feedbacks. Here we study a three-species ecological module called apparent competition, in which the predator is evolving in a trait that determines its interaction with two prey species. Unlike previous studies on apparent competition, which employed evolutionary frameworks with greatly simplified genetics, we study a multilocus eco-evolutionary model in which the predators evolving trait is determined by two diallelic loci. We ask how eco-evolutionary feedbacks with these two loci affect the coexistence of the prey species and the maintenance of polymorphisms within the predator species. In doing so, we uncover a novel eco-evolutionary feedback between the prey species and the linkage disequilibrium of the two loci of the predator. Through a stability analysis, we demonstrate how these feedbacks affect polymorphisms at both loci and, among others, may generate stable cycling.