Performance, Personality, and Energetics: Correlation, Causation, and Mechanism

Abstract

The study of phenotypic evolution should be an integrative endeavor that combines different approaches and crosses disciplinary and phylogenetic boundaries to consider complex traits and organisms that historically have been studied in isolation from each other. Analyses of individual variation within populations can act to bridge studies focused at the levels of morphology, physiology, biochemistry, organismal performance, behavior, and life history. For example, the study of individual variation recently facilitated the integration of behavior into the concept of a pace-of-life syndrome and effectively linked the field of energetics with research on animal personality. Here, we illustrate how studies on the pace-of-life syndrome and the energetics of personality can be integrated within a physiology-performance-behavior-fitness paradigm that includes consideration of ecological context. We first introduce key concepts and definitions and then review the rapidly expanding literature on the links between energy metabolism and personality traits commonly studied in nonhuman animals (activity, exploration, boldness, aggressiveness, sociability). We highlight some empirical literature involving mammals and squamates that demonstrates how emerging fields can develop in rather disparate ways because of historical accidents and/or particularities of different kinds of organisms. We then briefly discuss potentially interesting avenues for future conceptual and empirical research in relation to motivation, intraindividual variation, and mechanisms underlying trait correlations. The integration of performance traits within the pace-of-life-syndrome concept has the potential to fill a logical gap between the context dependency of selection and how energetics and personality are expected to interrelate. Studies of how performance abilities and/or aspects of Darwinian fitness relate to both metabolic rate and personality traits are particularly lacking.

Selection on the morphology–physiology‐performance nexus: Lessons from freshwater stickleback morphs

“…This is most pronounced in relation to AMR in the small‐plated KAR population (Figure 2i): differences in ellipses describing drift/neutral and contemporary phenotypic distributions are predominantly driven by metabolism; however, divergence of ellipses is also apparent along the axis corresponding to critical swimming speed (abscissa), more so than observed in relation with SMR (Figure 2d) or plate area (Figure 2n). This interpretation also aligns with the hypothesis that selection acts more directly on behavior and/or energetics than on performance traits (Careau & Garland, 2012), a notion lending further urgency to arguments for inclusion of physiology in studies of adaptive divergence.…”

“…Indeed, it is argued that energetics plays a central role in mediating the physiology–morphology–performance–fitness paradigm (Arnold, 1983; Careau & Garland, 2012); thus, metabolic rate may be viewed as a parameter of fundamental importance. As many factors both intrinsic and extrinsic to the individual have an influence on metabolic rate, measurements are typically divided between resting/basal and active states.…”

Thermal preference predicts animal personality in Nile tilapia Oreochromis niloticus

“…covariation has been previously hypothesised in which personality types mirror variation in metabolic patterns (Biro & Stamps 2010;Careau & Garland 2012;Metcalfe, Van Leeuwen & Killen 2015). Alternatively the impact of the effects of stress on thermal preference due to emotional fever could also explain the change in fish distribution with naïve animals experiencing higher stress responses to the novel tank environment .…”

Reduction of Energetic Demands through Modification of Body Size and Routine Metabolic Rates in Extremophile Fish

“…Instead, fish from extreme habitats generally had a higher activity than those from the ancestral nonsulfidic surface population, and sex differences were idiosyncratic across all populations investigated (significant three-way interaction term including presence of light, presence of H 2 S, and sex; see the appendix for details). Nonetheless, future studies should more rigorously test how individual variation in behavior affects met- abolic rates and vice versa (see Biro and Stamps 2010;Careau and Garland 2012).…”