Spontaneous activity rates and resting metabolism: Support for the allocation model of energy management at the among‐individual level

Abstract

Despite continuing interest in the proximate energetic constraints on individual variation in behavior, there is presently equivocal evidence for correlations between metabolism and behavior at the among‐individual level. Possible reasons for this include imprecise estimates of individual mean behavior and metabolism due to no repeated measures on one or more of the traits, analyses that do not take into account the labile nature of these traits and the uncertainty in individual estimates, and changing environmental conditions not accounted for. In this empirical study, we repeatedly measured activity rates and resting metabolic rates (RMR) of individual male mosquitofish over an extended period, lasting several months under constant laboratory conditions. Repeatability of each trait was significant (RMR: R = .41; activity: R = .72), indicating consistent variation among individuals, making covariance between them possible. Contrary to expectations, bivariate mixed model analysis revealed that more active individuals had lower RMR (r = −.58) after accounting for mass effects and other covariates. This result suggests that high activity rates require individuals to allocate less energy toward maintenance, and thus provides evidence for the “allocation” model of energy management. We suggest that it would be valuable to study whether and how behavior‐RMR correlations change over individual lifetime, a topic that has yet to be addressed.

Relationship between individual metabolic rate and patch departure behaviour: evidence from aquatic gastropods

“…Hence, in a similar way to larger foragers, foragers with higher metabolic rates are expected to exploit the resource faster when it is abundant and to leave resource patches earlier and at higher resource densities than foragers of similar size but with lower metabolic rates. However, negative correlations between basal metabolic rate and activity levels have also been observed (Cano and Nicieza 2006, Biro et al 2019), supporting the alternative hypothesis that those individuals with higher resting metabolic rates allocate less energy to movement and other behavioural activities (Nilsson 2002, Careau et al 2008). These conflicting findings underline the need for a more comprehensive exploration of the variations in foraging behaviour linked to foragers’ individual energetics.…”

Meta-analysis reveals that resting metabolic rate is not consistently related to fitness and performance in animals

“…The allocation of metabolic resources is therefore fundamentally different between endotherms and ectotherms, which might affect the correlation between RMR and fitness. The extensive variation in RMRwhich is often repeatable within individuals (Nespolo and Franco 2007;Auer et al 2016;Biro et al 2020) and heritable across generations (White and Kearney 2013;Pettersen et al 2018)is hypothesized to have consequences for fitness due to correlations between fitness-related traits and RMR (Burton et al 2011). Two main mechanistic hypotheses for the correlation between RMR and fitness have been proposed and tested in a variety of systems.…”

Integrating humans into pace-of-life studies: The Big Five personality traits and metabolic rate in young adults

“…In other words, individuals could be able to sustain energetically demanding personalities (or the behaviors associated with these personalities) by spending less energy at rest. Such a trade-off has been observed between metabolic rate and boldness in fall field crickets ( Gryllus pennsylvanicus ) [ 30 ] and with activity in mosquito fish ( Gambusia holbrooki ) [ 31 ]. In humans, there have been suggestions that total daily energy expenditure is bounded to a fixed level such that an increase in daily energy expenditure (e.g., by engaging in physical activity) is associated with a corresponding decrease in basal energy expenditure [ 32 ].…”