Evolutionary Mismatch and How To Evaluate It: A Basic Tutorial

ABSTRACT: Evolutionary mismatch is a state of disequilibrium whereby an organism that evolved in one environment develops a phenotype that is harmful to its fitness or well-being in another environment. Mismatch is an integral part of evolution in changing environments and is becoming increasingly common for all species living in human-altered environments. It is especially important to understand mismatch in relation to our own species since humans have so radically altered their own environment and mismatches can occur for cultural evolution in addition to genetic evolution. The first part of the article provides a basic tutorial on evolutionary mismatch by clarifying central concepts in mismatch: that of ancestral environment (E1), the novel environment (E2), and the trait under study (T). Our explanation of the concept of ‘evolutionary mismatch’ necessitates not only theoretical but also practical elaboration and exploration of the following list of properties and assumptions in order to confirm the application of a mismatch model in real life cases –identifying the population, the traits, inheritance mechanism, selection pressures and fitness consequences of associated traits in E1 and E2, and lastly integrating proximate and ultimate explanations for the study of the traits in E1 and E2. The final section presents a list of practical questions for evaluating evolutionary mismatch hypotheses. We expect that even professional evolutionists can benefit from our “back to basics” approach to one of the central concepts of evolutionary theory.