Abstract Bioenergetic models predict co-variation between physiological and behavioral traits that contribute to energy expenditure and income. These predictions rarely consider, however, whether flexible phenotypic expression in seasonal mammals affects trait co-regulation. To investigate whether bioenergetic mechanisms are stable over time, or change dynamically in response to environmental conditions and life-history stage, we tested seasonal co-variation between metabolic and behavioral phenotypes in a highly flexible marsupial, the monito del monte (Dromiciops gliroides). Our results support the bioenergetic performance model, where high basal metabolic rate, which represents high maintenance costs, indicates a higher rate of energy processing to support proactive behavior. We also demonstrated, however, that metabolic correlates of behavior shifted across the transition from post-hibernation recovery to the onset of the breeding season. After emergence from hibernation in October, exploration rate was significantly positively associated with maintenance metabolism, in contrast, in November, exploration was significantly positively associated with aerobic capacity, which defines the upper limit energy available for investment in performance. These findings demonstrate that in wild animals inhabiting seasonal environments, trait co-variation is not static but seasonally dynamic. We suggest that such flexibility may enable individuals to meet changing ecological and life-history demands, and highlights the importance of incorporating temporal dynamics into bioenergetic models of trait integration.
Tyers et al. (Fri,) studied this question.