부산대학교 도서관

Basal metabolic rate (BMR) represents the lowest level of aerobic metabolism in a resting, postabsorptive endotherm as measured within the thermoneutral zone. By contrast, maximal metabolic rate (V˙O2max) reflects the upper limit of aerobic metabolism achieved during intensive exercise. As BMR and V˙O2max define the boundaries of the possible levels of aerobic metabolism expressed by a normothermic individual, a key question is whether BMR and V˙O2max are correlated. In the present study, we took repeated paired measurements of thermoneutral resting metabolic rate (RMRt) and V˙O2max on 165 white-footed mice (Peromyscus leucopus). Over a single summer (May–October), repeatability (R ± SE) was low but statistically significant (P<0.05) for both RMRt and V˙O2max (R=0.15±0.08 for RMRt; R=0.27±0.12 for V˙O2max). Willingness to run during the forced-exercise trials was also significantly repeatable (R=0.16±0.08). At the residual level (within individual), RMRt and V˙O2max tended to be positively correlated (re=0.23±0.11, P=0.051), suggesting the presence of correlated phenotypic plasticity. By contrast, RMRt and V˙O2max were significantly negatively correlated at the among-individual level (rind=−0.84±0.40). To the extent that variation in RMRt reflects variation in BMR, the negative among-individual correlation does not corroborate the idea that a costly metabolic machinery is needed to support a high V˙O2max. Future research should investigate the (genetic) relationship between RMRt (and BMR) and other energetically expensive behaviors and activities to better understand how energy is allocated within individuals. [ABSTRACT FROM AUTHOR]