The idea that ecology matters to long term evolutionary change was a prominent element in the Modern Synthesis of mid-century that bridged three main areas of evolutionary study: adaptation, speciation, and evolutionary trends. Our general goal is to understand this potential interplay of adaptation and historical contingency in ecological and taxonomic diversification, as well as the marks of evolutionary history on community structure. The context of nearly all of our studies is the interaction between insects and their hostplants, ecological associates whose diversity and abundance make them the principal denizens of the terrestrial earth, and other kinds of interspecific interactions.