My research interests are the physiological ecology and evolutionary physiology of small mammals. In particular, I am interested in studying the proximate (i.e., non-evolutionary) and evolutionary factors that shape intraspecific variation of energy use in small mammals. I am interested in how energy use such as metabolic rate has evolved, including the evolution of the tradeoffs between energy use for immune function, thermoregulation and reproduction. I have examined the role of hormones such as thyroid, leptin and cortisol on energy use. Additionally, while most of my research has focused on addressing proximate factors or underlying mechanisms that influence physiological traits in small mammals, some of my research has entailed examining patterns of intraspecific variation as part of understanding whether and how evolution for physiological traits may have occurred. More recently, I have been investigating the relationship between immune function and energy use and the effect of stress on both.