Glenn E. Walsberg
Ecological Physiology and Biophysical Ecology
Dr. Walsberg's research focuses on the environmental physiology and biophysical ecology of birds and mammals. His research includes the following:
(A) Animal energetics, including both the physiology of energy metabolism and heat transfer as well as the use of energy as a vital resource by organisms. Energy relations have broad significance for the function and success of organisms, and therefore use of chemical potential energy and its consequent metabolic heat production has been a major theme in modern biology. Animal energy usage has most commonly been quantified by indirect calorimetry, which is almost always based upon rates of oxygen consumption or carbon dioxide production. An important complication in such analyses is that the relationship between respiratory gas exchange and metabolic heat production is intricate and variable. My analyses demonstrated that significant gaps exist in our knowledge of these relations and of the respiratory metabolism of animals. These uncertainties could have important consequences for our understanding of ecological energetics because they may produce substantial (e.g., >30%) errors in energetic analyses that are large compared to differences in energy expenditure underlying important ecological phenomena. I am therefore rigorously quantifying the relationships between metabolic heat production and respiratory gas exchange, and determining their sensitivity to variables (e.g., diet composition, thermoregulatory challenges).
(B) Ecological physiology of desert mammals. Because of their high temperatures and absence of water, subtropical deserts offer the greatest physiological challenges experienced by terrestrial organisms. Small mammals are one of the most conspicuously successful groups of animals in these habitats, but their ability to occupy hot deserts is fundamentally unexplained. One reason for this is that the climates they experience are substantially hotter and drier than generally appreciated, and are sufficiently extreme such that occupation of subtropical deserts by small mammals is not consistent with current knowledge of their physiology. One focus of Dr. Walsberg's research, therefore, is to quantify the thermal and hydric environments experienced by free-living desert mammals and to quantify the relative importance of the physiological mechanisms that allow them to occupy hot subtropical deserts.
(C) Determinants and consequences of solar heat in birds and mammals. Solar heat gain can importantly affect an animal's thermoregulatory physiology and energy balance, and is a complex function of environmental properties as well as animal properties that may be readily apparent (e.g., surface coloration) or subtle (e.g., hair optical properties). Dr. Walsbergs research has explored the manner in which such determinants are adaptively altered to modify radiative heat gain independent of coloration patterns important for visual communication or crypsis.
In each of these areas, a primary goal is to establish the role of relevant physiological mechanisms in determining the success of animals in nature. Consequently, Dr. Walsberg's research integrates laboratory and field approaches, and subsumes behavioral, biophysical, and physiological techniques.
Selected Publications
Wooden, K.M. and G.E. Walsberg. 2004. Temperature and locomotor capacity in a heterothermic Rodent. Journal of Experimental Biology, in press.
Cooper, C.E., G.E. Walsberg, and P. C. Withers. 2003. Biophysical properties of the pelt of the numbat (Myrmecobius fasciatus) and its role in thermoregulation. Journal of Experimental Biology 206: 2771-2777.
Walsberg. G.E. 2003. How useful is energy balance as an overall index of stress in animals? Hormones and Behavior 43: 16-17.
Tracy, R.L. and G.E. Walsberg. 2002. Kangaroo rats revisited: re-evaluating a classic case of desert survival. Oecologia 133:449-457.
Wooden, K.M. and G.E. Walsberg. 2002. Effect of environmental temperature on body temperature and metabolic heat production in a heterothermic rodent, Spermophilus tereticaudus. Journal of Experimental Biology 205: 2099-2105.
Tracy, R.L. and G.E. Walsberg. 2001. Intraspecific variation in water loss in a desert rodent, Dipodomys merriami. Ecology 82: 1130 -1137.
Tracy, R.L. and G.E. Walsberg. 2001. Developmental and acclimatory contributions to water loss in a desert rodent: investigating the time course of adaptive change. Journal of Comparative Physiology B 171: 669-679
Tracy, R. L. and Walsberg, G. E. 2000. Prevalence of cutaneous evaporation in Merriam's kangaroo rat and its adaptive variation at the subspecific level. Journal of Experimental Biology 203: 773-781.
Wooden, K.M. and G.E. Walsberg. 2000. Effect of wind and solar radiation on metabolic heat production in a small desert rodent, Spermophilus tereticaudus. Journal of Experimental Biology 203: 879-888
Wolf, B.O. and G.E. Walsberg. 2000. The role of the plumage in heat transfer processes in birds. American Zoologist 40:575-584.
Wolf, B.O., K.M. Wooden, and G.E. Walsberg. 2000. Effects of complex radiative and convective environments on the thermal biology of white-crowned sparrows (Zonotrichia leucophrys). Journal of Experimental Biology 203: 803-811.
Tracy, R.L. and G.E. Walsberg. 2000. Unappreciated tolerance to high ambient temperatures in a widely distributed desert rodent, Dipodomys merriami. Physiological and Biochemical Zoology 73: 809-818.
Walsberg, G.E. 2000. Small mammals in hot deserts: some generalizations re-visited. Bioscience 50: 109-122.
Chu, M. and G.E. Walsberg, G.E. 1999. Phainopepla, Phainopepla nitens. In, The Birds of North America, no. 415 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA
Hoffman, T.C.M. and G.E. Walsberg. 1999. Inhibiting ventilatory evaporation produces adaptive increase in cutaneous evaporation in mourning doves, Zenaida macroura. Journal of Experimental Biology 202: 3021-3028.
Van Hoek, A., R. Tracy, G.E. Walsberg, and D. Brown. 1999. Absence of aquaporin-4 from the kidney of the desert rodent Dipodomys deserti: A naturally occurring AQP4 knockout model. Journal of the American Society of Nephrology A132.
Walsberg, G.E., R. Tracy, and T. Hoffman. 1997. Do metabolic responses to solar radiation scale directly with intensity of irradiance? Journal of Experimental Biology 200:2115-2121.
Wolf, B.O. and G.E. Walsberg. 1996. Respiratory and Cutaneous Evaporative Water Loss at High Environmental Temperatures in a Small Bird. Journal of Experimental Biology 199: 451-457.