Evolutionary physiology is the study of the biological evolution of physiological structures and processes; that is, the manner in which the functional characteristics of organisms have responded to natural selection or sexual selection or changed by random genetic drift across multiple generations during the history of a population or species.
Accordingly, the range of phenotypes studied by evolutionary physiologists is broad, including life history traits, behavior, whole-organism performance,[3][4] functional morphology, biomechanics, anatomy, classical physiology, endocrinology, biochemistry, and molecular evolution.
This period was followed by attempts in the early 1980s to integrate quantitative genetics into evolutionary biology, which had spillover effects on other fields, such as behavioral ecology and ecophysiology.
It generated vigorous debate, and within a few years the National Science Foundation had developed a panel titled Ecological and Evolutionary Physiology.
For example, an understanding of physiological mechanisms can help in determining whether a particular pattern of phenotypic variation or co-variation (such as an allometric relationship) represents what could possibly exist or just what selection has allowed.