Community genetics looks at how genetic variation within a species, or group of species, changes other species in an ecosystem or the ecosystem as a whole. These changes can involve species presence or abundance; the behavior, physiology, or evolution of a species; or the rates of ecosystem processes. The question at the core of community genetics is “How do genotypes differentially influence associated species and ecosystems?” Community genetics takes ideas from population genetics and community ecology, and in so doing provides a way of integrating the disciplines of ecology and evolution.