Integrating historical and mechanistic biology enhances the study of adaptation

Adding a causal, mechanistic dimension to the study of character evolution will increase the strength of inferences regarding the evolutionary history of characters and their adaptive consequences. This approach has the advantage of illuminating mechanism and testing evolutionary hypotheses rigorously. We consider the advantages of combining mechanistic and historical biology in the study of behavior, physiology, and development. we present six examples to illustrate the advantages: (1) preexisting biases in sound perception in frogs; (2) preexisting biases in visual cues in swordtail fishes (3) exploitation of prey location behavior for attraction of mates in water mates; (4) heterospecific mating in asexual molly fishes: (5) developmental foundation of morphological diversification in amphibian digits; and (6) locomotor performance at low temperature and the evolution of nocturnadity in geckos. In each of these examples, the dominant role of history, combined with organasmal integration, makes ignoring history a risky proposition.