CAREER: Mechanisms and tradeoffs of dietary specialization in mammalian herbivores

University Of Utah, Salt Lake City UT

Investigators

Abstract

Limitations of the detoxification system in processing plant toxins are implicated as the mechanism explaining the paucity of dietary specialization among mammalian herbivores. In fact, little is known about how wild herbivores metabolize plant toxins and how detoxification restricts dietary specialization. Detoxification constraints are of current interest given that the toxin concentrations of many plants will double within the next century due to rising atmospheric CO2 levels. The overarching goals of the research are to understand the mechanisms that permit and tradeoffs associated with dietary specialization in herbivorous woodrats (Neotoma). Specialist woodrats are predicted to absorb lower concentrations of plant toxins compared to generalists. The research examines 3 mechanisms that may decrease toxin absorption: 1) tannin-binding proteins 2) p-glycoproteins and 3) intestinal detoxification. Specialists and generalists will be compared to determine how they differ with respect to these mechanisms. Biochemical and pharmacological methods will be employed. In addition, theory predicts that specialists have detoxification systems that are more efficient in processing plant toxins in their diet compared to generalist herbivores processing the same compounds. However, the superior ability that specialists have in processing toxins from their diet is predicted to compromise their efficiency to biotransform novel toxins, which are not contained in their normal diet. The potential tradeoffs of dietary specialization will be addressed by comparing 1) maximal levels of novel toxins that specialists and generalists can ingest; 2) capacities of detoxification pathways (functionalization and glucuronidation) using probe drugs; and 3) surveying the detoxification systems of generalists and specialists with DNA microarrays. For the education component, an intensive course is proposed for mid-level students (sophomore-junior) to train them in various aspects of research by using this research project as the example and opportunity. This course, "Scientific Immersion", will be offered in the fall semester each year to a maximum of five students.