Meeting Abstract
Aerobic performance is strongly tied to fitness as it often determines an animal’s ability to find food, escape predators, or survive extreme conditions. At high-altitude, where severe reductions in O2 availability and cold temperatures prevail, maximum metabolic heat production (thermogenesis) is a performance trait that has evolved under natural selection. Understanding how thermogenesis evolves to permit survival at high-altitude will yield insight into the links between integrated physiology, whole-organism performance, and fitness. Previous work in deer mice (Peromyscus maniculatus) suggests that low O2 availability at high-altitude forces a trade-off, whereby developing deer mouse pups delay the onset of thermogenesis in order to preserve limited energetic resources. In order to determine the mechanistic causes of this delay, we analyzed the transcriptomes of thermogenic organs, brown adipose tissue (BAT) and skeletal muscle, across the first 27 days of post-natal development in deer mice native to low- and high-altitude. We show that developmental delays in thermogenesis are correlated with shifts in the expression of gene regulatory networks that function in nervous system control, fuel supply, and vascularization of BAT, and aerobic metabolism and mitochondrial function in skeletal muscle. These results suggest that the delay in thermogenesis is attributable to a delay in the activation and aerobic capacity of thermo-effector organs. We provide evidence that many of the regulatory changes are adaptive. Our results suggest that a delay in the development of thermo-generation is adaptive at high-altitude, and may represent an alternative resource allocation strategy to balance competing energetic trade-offs.
