University of Utah Undergraduate Research Abstracts, Volume 3, Spring 2003

Plant Toxins Alter the Feeding Patterns of Desert Woodrats

PLANT TOXINS ALTER THE FEEDING PATTERNS OF DESERT WOODRATS Theory predicts that mammalian herbivores regulate concentrations of toxins in the blood by modifying the size, duration and frequency of feeding bouts. We hypothesized that increasing concentrations of plant toxins in the diet will cause a decrease in meal size and duration, while the number and frequency of meals will increase. This hypothesis was tested by feeding <Neotoma lepida>, a herbivorous woodrat, diets containing increasing concentrations of creosote resin, a toxic component present in its natural diet of creosote leaves. Foraging behavior was observed every 60 seconds following administration of 0, 1.5, 3, or 6% toxic diet. We found that meal size and duration as well as the number and frequency of meals decreased with increased toxin concentration. Moreover, animals were not able to maintain daily food intake on diets containing toxins. We suggest that the toxin concentrations used exceeded the toxin elimination capacity of animals. An inability to eliminate toxins quickly may prevent animals from increasing frequency of meals and cause the observed decreased in daily food intake. Our results demonstrate that increasing concentrations of plant toxins alters the feeding behavior of mammalian herbivores. Additionally, these results suggest that animals regulate toxin intake at the meal level by altering meal size with increased toxin concentrations. Emily K. Heward Senior Biology [e-mail] Faculty Sponsor: M. Denise Dearing Dept. of Biology [e-mail] Faculty Sponsor: Jennifer Sorensen- Forbey Dept. of Biology [e-mail] 57