PARENT SESSION
Poster Session # 1: Ecological Theory and Evolutionary Ecology.

Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Latitudinal trends in energy expenditure of endotherms.

Anderson, Kristina^*,1, ¹ University of New Mexico, Albuquerque, NM

ABSTRACT- Energy expenditure (field metabolic rates) of endotherms scales allometrically with body mass, but the remaining variation is not well understood. The purpose of this study is to examine how energy expenditure varies with environmental factors and species characteristics after accounting for mass. When plotted against latitude, mass-corrected field metabolic rates of approximately 200 bird and mammal species fall within a constraint triangle consisting of a flat upper bound and a lower bound that increases with latitude. Thus, endotherms are constrained to increasing energy expenditure (relative to body size) with increasing latitude, but are free to vary between this constraint and an upper limit of sustainable energy expenditure. An examination of some correlates of latitude suggests that the lower bound of this relationship is controlled by temperature and that ecosystem productivity does not predict energy expenditure. Species characteristics such as diet and life history play a role in determining where an animal falls within the constraint triangle. These macroecological patterns provide insight toward an integrated, theoretical understanding of energy expenditure of endotherms.

Key words: endotherms, latitude, macroecology, energy expenditure/ field metabolic rate