부산대학교 도서관

To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1365-2435.2009.01559.x Byline: Michael W. Sears (2), Jack P. Hayes (1), Marilyn R. Banta (3), Donna McCormick (1) Keywords: activity; cold tolerance; Peromyscus; physiological; metabolism Abstract: Summary 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. 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. 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 [degrees]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. 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. 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. 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. Author Affiliation: (1)Department of Biology, MS 314, University of Nevada, Reno, Reno, NV 89557, USA; (2)Department of Zoology, Center for Ecology, Southern Illinois University, Carbondale, IL 62901, USA; and (3)Department of Biology, Texas State University-San Marcos, 601 University Dr., San Marcos, TX 78666, USA Article History: Received 20 June 2008; accepted 12 February 2009Handling Editor: Peter Niewiarowski Article note: (*) Correspondence author. E-mail: msears@zoology.siu.edu