Study of evolutionary changes in physiological characteristics
Natural and sexual selection are often presumed to act most directly on behavior (e.g., what an animal chooses to do when confronted by a predator), which is expressed within limits set by whole-organism performance abilities (e.g., how fast it can run) that are determined by subordinatetraits (e.g., muscle fiber-type composition). A weakness of this conceptual and operational model[1] is the absence of an explicit recognition of the place of life history traits.
^Lovegrove, B. G. (2006). "The power of fitness in mammals: perceptions from the African slipstream". Physiological and Biochemical Zoology. 79 (2): 224–236. doi:10.1086/499994. PMID16555182. S2CID24536395.