Trait-shift induced interaction modification and unusual consequences on
ecosystem dynamics

Ecosystems are traditionally modeled by networks of species with constant interaction strengths between them. However, it has been increasingly recognized that there is substantial intraspecific variation in ecologically important traits. The distribution of such traits within a species can shift in response to environmental change or interaction with other species. Although some work has examined how heritable trait variation affects eco-evolutionary dynamics, non-heritable variation caused by phenotypic plasticity, developmental differences, or species interactions may also affect the outcome of population dynamics. Using simplified models of ecosystems, I will illustrate that the dynamic shift of trait distribution within a species can modify its interactions with other species, leading to outcomes that are otherwise unexpected. These include the emergent promotion of a prey population by its predator, the facilitation of a predator by its competitor, and the coexistence of species that would otherwise exclude each other.