An evolutionary perspective on conflict and compensation in physiological and functional traits

Abstract

Abstract Physiological and functional traits, especially those related to behavior and whole-organism performance capacities, are subject to a variety of both parallel and opposing natural and sexual selection pressures. These selection pressures show considerable interspecific variation, shaping contemporary behavioral and functional diversity, but the form and intensity of selection on physiological and functional traits can also vary intraspecifically. The same suites of traits can experience quite different selection pressures, depending on the sex or age of a given individual, as well as the presence and nature of alternative reproductive strategies and tactics. These interand intra-locus genetic conflicts have potentially important consequences for the evolutionary trajectories of traits subject to them. Consequently, any intraspecific conflicts which could displace traits from their selective optima in certain classes of individuals relative to others are expected to result in selection for mechanisms to compensate for deviation from those optima. Such conflicts include interlocus sexual conflict, intralocus sexual conflict, and interacting phenotypes, as well as conflict within a sex. In this paper, we consider the evidence for, and implications of, such conflicts for physiological and functional traits in diverse taxa, including both vertebrates and invertebrates, and evaluate the various mechanisms, ranging from behavioral and mechanical to energetic and genetic, enabling compensation. We also discuss how preand post-mating conflicts, as well as interacting phenotypes, might affect the evolution of behavior and physiological and functional traits. Investigators that seek to understand the links among behavior, morphology, physiology, and function should consider such conflicts.