Meeting Abstract

P3.125  Jan. 6  Low idle, low ceiling, and low activity? Energetic answers from a Peromyscus mouse model STEYERMARK, AC*; AZAR, BL; HAUSTEIN, MD; HEITZMAN, MA; KENT, KJ; RICE, LN; VERANT, ML; WEBER, BJ; Univ. St. Thomas; Univ. St. Thomas; Univ. St. Thomas; Univ. St. Thomas; Univ. St. Thomas; Univ. St. Thomas; Univ. St. Thomas; Univ. St. Thomas acsteyermark@stthomas.edu

Basal metabolic rate (BMR) can be viewed as “maintenance metabolism”, or the the minimum metabolic rate that an organism must sustain to maintain basic bodily functions while at rest, and varies among and within species as a result of varying ecological and physiological factors. Net primary productivity (NPP) has been proposed as a unifying explanation for variability in metabolic rates between populations or species in suggesting a positive correlation between BMR and the productivity of the region in which a species evolved. At the same time, some studies have suggested relationships between BMR and maximal metabolic rate (MMR) and daily activity levels. Here, we test the prediction that individuals that evolved in low-productivity environments are adapted to low energy expenditure by exhibiting low BMR, low MMR and low activity using a Peromyscus mouse model. We report significant positive relationships between NPP and both BMR and MMR, but not between NPP and activity. In addition, we report a significant positive relationship between BMR and dry liver and kidney masses, but not with dry small intestine mass. Lastly, T4 thyroxine hormone levels were not correlated with BMR. The relationships between NPP and both BMR and MMR further support the idea that under limiting conditions, organisms evolve to idle low and run low.