Biology subjects

Careau, V.

Publications and source records attributed to Careau, V..

2 recordsLinked to original sources

bioRxiv2025

No rest for the rodent: energy management strategies in the naked mole-rat

Organisms have access to a limited amount of energy that must be distributed among multiple physiological processes. Broadly, the total daily energy expenditure (DEE) can be partitioned into maintenance costs (i.e., resting metabolic rate RMR) and active energy expenditure (AEE). The slope (b) between DEE and RMR provides insights into energy management strategies. In the additive model, where changes in activity are independent of maintenance energy, DEE and RMR follow a part-whole relationship with b=1. In the allocation model, where increased activity requires compensatory reductions in maintenance costs, a limit on DEE causes a DEE-RMR relationship with b<1. In the performance model, increased activity causes an increase in maintenance costs, which causes a DEE-RMR relationship with b>1. Despite their high lifetime energy expenditure and resistance to age-related metabolic decline, energy management is yet to be explored in the African naked mole-rat (NMR, Heterocephalus glaber). To investigate metabolic strategies in the NMR, repeated metabolic and activity measurements were taken in 32 individual NMRs using a multiplexed metabolic system. DEE was not repeatable, thus the DEE-RMR covariance at the among-individual level could not be fitted. At the within-individual level, however, the positive correlation between RMR and activity and the DEE-RMR relationship with b > 1 indicated support for the performance model. Hence, our results indicate that within-individual changes in activity and RMR are associated, suggesting that when a NMR increases activity on a given day, the impact on DEE are disproportionate because of a concurrent increase RMR.

ecology↗

bioRxiv2020

Derivation of predator functional responses using a mechanistic approach in a natural system

The functional response is central to our understanding of any predator-prey system as it establishes the link between trophic levels. Most functional responses are evaluated using phenomenological models linking predator acquisition rate and prey density. However, our ability to measure functional responses using such an approach is often limited in natural systems and the use of inaccurate functions can profoundly affect the outcomes of population and community models. Here, we develop a mechanistic model based on extensive data to assess the functional response of a generalist predator, the arctic fox (Vulpes lagopus), to various tundra prey species (lemmings and the nests of geese, passerines and sandpipers). We found that predator acquisition rates derived from the mechanistic model were consistent with field observations. Although sigmoidal functional responses were previously used to model fox-prey population dynamics, none of our simulations resulted in a saturating response in all prey species. Our results highlight the importance of predator searching components in predator-prey interactions, especially predator speed, while predator acquisition rates were not limited by handling processes. By combining theory with field observations, our study provides evidences that predator acquisition rate is not systematically limited at the highest prey densities observed in a natural system. We reinforce the idea that functional response categories, typically types I, II, and III, should be considered as particular cases along a continuum. Specific functions derived with a mechanistic approach for a range of densities observed in natural communities should improve our ability to model and understand predator-prey systems.

ecology↗