Document: JEN-3-43-14

Clearance rate of plant toxins: A mechanism for dietary specialization in mammalian herbivores.

SORENSEN, J.S.* and M.D.DEARING

University of Utah, Salt Lake City, UT, 84112, USA ¹

Abstract:
Detoxification and elimination of plant toxins are thought to be responsible for limiting dietary specialization in mammalian herbivores. This hypothesis, known as the detoxification limitation hypothesis, predicts that the few mammalian specialists that do exist should have adaptations for rapid detoxification and elimination of plant secondary compounds. We tested whether specialists clear toxins from their circulation faster than generalists. We compared the clearance rate of a plant toxin in closely related specialist (Neotoma stephensi) and generalist (N. albigula) woodrats. Both species were orally gavaged with alpha-pinene, the predominate monoterpene found in the host plant of the specialist. We collected venous blood 3, 6, 10, 15, 20, 60, 90, and 140 minutes post-gavage. Blood was analyzed for alpha-pinene concentration using head-space gas chromatography. We found that specialists possess faster clearance rates than generalists when orally dosed with alpha-pinene. The concentration of alpha-pinene detected in the blood stream of the generalist was 5.5 6.4 times greater than in the specialist over all time intervals. The faster clearance rate of the specialist may allow them to have higher intakes of toxic diets. These data suggest one mechanism that may facilitate dietary specialization and support the detoxification limitations hypothesis.

Keywords: alpha-pinene, clearance rate, dietary specialization, Neotoma, plant toxin

This abstract is being presented at: 11:15 AM in session:
Oral Session #21: Small Mammal Population Ecology.