Behavioral plasticity in two endemic rodents from the Andes Mountains: strategies for thermal and energetic balance

Abstract

Environmental changes involve trade-offs to the thermal and energetic balances that animals face through a diversity of physiological and behavioral strategies. In Abrothrix andinus and Akodon spegazzinii, two small rodents inhabiting the Andes Mountains, some physiological traits relevant to their thermal and energetic balance (e.g., conductance, basal metabolic rate) show relatively low plasticity. Therefore, behavioral plasticity could be a crucial mechanism for their adaptation to the environmental variability of their habitats. Following the circadian thermo-energetic hypothesis, we explored the frequency and pattern of locomotor activity in response to different energetic demands caused by experimental variations in ambient temperature (5, 16, and 31 °C) and food availability (ad libitum and deprivation) in these species. Our data revealed that the behavioral strategy for coping with such challenges differs among species and populations, and suggest that, depending on the particular ecological context, it may facilitate or hinder thermal and energetic balance. Furthermore, we found that, consistently with a more limited altitudinal distribution, A. spegazzinii exhibits lower behavioral plasticity than A. andinus. In the context of global climate change, phenotypic plasticity is key to species resilience, and the assessment of behavioral traits provides fundamental inputs for modeling the potential impact of future scenarios on the persistence of small highland mammals.