Species constantly engage in strong interactions with other species - parasites, predators, prey, and mutualists. As a result, their traits may coevolve and diversify in geographic mosaics.
1999. Thyme is of the essence: Biochemical polymorphism and multi-species deterrence. Evolutionary Ecology Research 1: 151-171. Linhart YB 1999. Mosaic landscapes, family structure, and evolution.