PARENT SESSION
Poster Session #31: Animal Population and Community Ecology I.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

The relationship between body size and energy flow in mammal communities.

Ernest, Morgan^*,1,2, Stevens, Richard², Willig, Michael², Brown, James¹, ¹ Department of Biology, Albuquerque, NM² Department of Biological Sciences, Lubbock, TX

ABSTRACT- A major theme in ecology is the influence of energy on community and ecosystem properties. While this research traditionally focused on the relationship between energy and species richness, current research increasingly focuses on the relationship between body size and energy flow. Two of these studies are Damuth's rule which finds that energy use by populations of species is independent of body size and Holling's Textural-Discontinuity Hypothesis which claims that species clump in body size space, reflecting underlying discontinuities in resource availability. These studies make contradictory predictions concerning energy flow through local communities. Damuth's rule implies that in local communities energy flow should be independent of body size while Holling's hypothesis predicts that energy flow should be body size specific and closely correspond with lumps of species in body size space. I examined these predictions using detailed community data for 5 small mammal communities from 4 different habitats: Chihuahuan desert, tropical rainforest, alpine tundra, and temperate coniferous forest. Individual body size was used to estimate the energy use for each individual using the allometric equation for basal metabolic rate. For all communities the relationship between the body size distribution and energy flow was highly multimodal. Furthermore, the mean body size for most species was closely associated with the modes in energy flow. These results lend support for Holling's Hypothesis and raises questions concerning the applicability of Damuth's rule to local communities.

KEY WORDS: body size, energy flow, Damuth's rule, Holling's Textural-Discontinuity Hypothesis