Costs of exploratory behavior: the energy trade-off hypothesis and the allocation model tested under caloric restriction

Abstract

In order to maintain the energy balance, animals often exhibit several physiological adjustments when subjected to a decrease in resource availability. Specifically, some rodents show increases in behavioral activity in response to food restriction; a response regarded as a paradox because it would imply an investment in locomotor activity, despite the lack of trophic resources. Here, we aim to explore the possible existence of trade-offs between metabolic variables and behavioral responses when rodents are faced to stochastic deprivation of food and caloric restriction. Adult BALB/c mice were acclimatized for four weeks to four food treatments: two caloric regimens (ad libitum and 60% restriction) and two periodicities (continuous and stochastic). In these mice, we analyzed: exploratory behavior and homecage behavior, basal metabolic rate, citrate synthase and cytochrome oxidase c enzyme activity (in liver and skeletal muscle), body temperature and non-shivering thermogenesis. Our results support the model of allocation, which indicates commitments between metabolic rates and exploratory behavior, in a caloric restricted environment. Specifically, we identify the role of thermogenesis as a pivotal budget item, modulating the reallocation of energy between behavior and basal metabolic rate. We conclude that brown adipose tissue and liver play a key role in the development of paradoxical responses when facing decreased dietary availability.

Food availability early in life impacts among and within individual variation in behaviour

“…This result seems contradictory since it might be expected that tadpoles in the low feed regime would have less energy and hence be less active than well fed tadpoles. A similar increase in the distance travelled under low-energy diets has been found in rodent species which can be attributed to a decrease in basal metabolic rate in order to allow more resources to be allocated to foraging activity (Overton and Williams 2004; Peña-Villalobos et al 2020). As X. leavis are filter feeders, the lower density of food in the low feed treatment may have meant that tadpoles would have had to increase their buccal pumping rate and swim further distances to increase their feed intake (Wassersung and Hoff 1979; Ryerson and Deban 2010).…”

Stability of olfactory behavior syndromes in the Drosophila larva

“…However, if behavior trait stabilities are heritable, they could explain why D. melanogaster strains derived from the same wild population display dramatic differences in their behavior responses to new odor environments [53][54][55] . They may also help us understand how and why starved animals show different degrees of search and exploratory behavior compared to non-starved animals [56][57][58] .…”

The active mouse rests within: Energy management among and within individuals

“…Indeed, previous studies that examined these relationships were either only looking at DEE versus RMR, RMR versus activity, or did not partition the covariances at the among‐ versus within‐individual levels (e.g. Biro et al., 2020; Careau, 2017; Careau et al., 2015, 2019; Peña‐Villalobos et al., 2020; Timonin et al., 2011). By looking at the slope of the DEE–RMR relationship, we found that the performance model was supported at the among‐individual level, whereas the allocation model applied at the within‐individual level.…”