Out in the cold: physiological capacity influences behaviour in deer mice

Abstract

Summary 1.Understanding the links between physiological performance and fitness is key to predicting the responses of individuals to environmental change, especially that imposed by climate. Of particular interest are traits linked with metabolic performance. In particular, maximal metabolic rate (MMR; which describes the upper limit to heat production) and basal metabolic rate (BMR; which describes the lower limit to heat production for a normothermic endotherm) are important causal mechanisms that determine the physiological limits for activity under cold conditions. 2. Previous work with deer mice has shown important links between maximal metabolic performance and activity. Selection for elevated MMRs was detected in nature, and higher rates of above-ground activity during periods of cold were associated with elevated MMRs. Here, we investigate further the links between activity and elevated MMRs. 3. We conducted a laboratory study to test whether BMR or MMR was correlated with activity and foraging behaviour of deer mice exposed to a series of cold temperatures (-5, -10 and -15 ° C). Each mouse had access to a warm nest box, but needed to enter a cold environmental chamber to access food, ice chips and a running wheel. Behaviours were monitored for 2 days under these experimental conditions. Prior to the experimental trials, BMR and MMR were measured. MMR was also measured after the trials. 4. The amount of time that mice spent active in the cold was negatively correlated with ambient temperature. The duration of activity per bout (when mice were out of the nest box) decreased at colder temperatures, but the number of bouts did not. The total duration of activity and duration per bout increased with an individual's MMR and change in MMR over the course of the experiment. Body mass decreased at colder temperatures, and mice with higher MMR and greater increases in MMR consumed more food. 5. Our study suggests that mice with high MMR, or a capacity to increase MMR may be best able to tolerate cold environments. Thus, physiological capacity and behaviour can influence each other in response to environmental conditions. 6. Integrative studies between behaviour and physiology in an ecological context provide greater understanding of the potential responses of organisms to environmental change. With respect to climate, such responses will depend either on the ability of individuals to induce plastic (or acclamatory) responses to environmental stressors or on the structure of genetic variation for physiological traits within a particular population. Although, some effort has been directed at understanding the evolutionary significance of metabolic traits (particularly with respect to heritabilities), we suggest that priority should be given to studies that explicitly address the mechanistic links between physiology and fitness in light of ongoing climate change.

The energy budget, thermogenic capacity and behavior in Swiss mice exposed to a consecutive decrease in temperatures

“…Energy budget in cold-exposed mice increasing feeding time (Johnson and Cabanac, 1982;Perrigo Bronson, 1985;Schwaibold and Pillay, 2006). Also in deer mice (Peromyscus maniculatus), the duration of activity per bout decreased at colder temperatures, and the amount of time spent active in the cold was negatively correlated with ambient temperature (Sears et al, 2009). Consistently, in the current study cold-exposed mice showed a reduction in the time spent on activity and exhibited increases in the time spent on feeding and resting behavior.…”

Geographic variation of resistance to water loss within two species of lungless salamanders: implications for activity

“…In birds, a decrease in abdominal temperature of the Gentoo penguin (Pygoscelis papua) was linked to reduced energetic costs while diving for prey (Bevan et al 2002). Also, deer mice (Peromyscus maniculatus) that consumed more food exhibited higher maximal metabolic rates that resulted in higher rates of activity in cold conditions, illustrating how behavioral decisions and physiological capacities influence the potential for energetic gain (Sears et al 2009). Thus, any variation in physiological traits that influence activity has direct implications for predicting the relationship between an organism and its environment.…”

Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance: a study on the Trinidadian guppy (Poecilia reticulataPeters)

“…Moreover, studies of physiological diversity may reveal the physiological basis of intraspecific variation in life history traits (Speakman, 2005;Arnott et al, 2006;Williams, 2012). Finally, phenotypic diversity may be indicative of genetic diversity and the degree to which a population can adjust to environmental change (Hayes and Jenkins, 1997;Bolnick et al, 2003;Sears et al, 2009).…”