Competitive speciation in quantitative genetic models

We study sympatric speciation due to competition in an environment with a b road distribution of resources. We assume that the trait under selection is a quantitative trait, and that mating is assortative with respect to this trait. Our model alternates selection according to Lotka-Volterra-type comp etition equations, with reproduction using the ideas of quantitative geneti cs. The recurrence relations defined by these equations are studied numeric ally and analytically. We find that when a population enters a new environm ent, with a broad distribution of unexploited food sources, the population distribution broadens under a variety of conditions, with peaks at the edge of the distribution indicating the formation of subpopulations. After a lo ng enough time period, the population can split into several subpopulations with little gene flow between them. (C) 2000 Academic Press.