  Coexistence of individuals with different species or phenotypes is often
found in nature in spite of competition between them. Stable coexistence of
multiple types of individuals have implications for maintenance of ecological
biodiversity and emergence of altruism in society, to name a few. Various
mechanisms of coexistence including spatial structure of populations,
heterogeneous individuals, and heterogeneous environments, have been proposed.
In reality, individuals disperse and interact on complex networks. We examine
how heterogeneous degree distributions of networks influence coexistence,
focusing on models of cyclically competing species. We show analytically and
numerically that heterogeneity in degree distributions promotes stable
coexistence.
