1Anthropology, Hunter College of the City of New York, 2Anthropology, The Graduate Center of the City University of New York, 3New York Consortium in Evolutionary Primatology (NYCEP)
Friday All day, Plaza Level
Hydrolyzable tannins (HT) and condensed tannins (CT) are high-molecular weight, polyphenolic compounds, and are the most common type of plant secondary metabolites. Studies have indicated they are a plant defense against herbivory because they can be toxic, are bitter tasting, and they bind dietary protein rendering it unavailable for digestion. We know little about how tannins differ intraspecifically within tree leaves in tropical climates. We selected seven tree species commonly consumed by black and white colobus (Colobus guereza) and red colobus monkeys (Procolobus rufomitratus), and examined them for HT and CT. For each tree species, we analyzed samples of young (YL) and mature leaves (ML) from at least 5 individual trees to assess how tannin levels vary intraspecifically according to crown layer, leaf maturity, and individual. It has been hypothesized that stress from increased light intensity may induce CT production in upper crown leaves, but we did not find this pattern (matched pairs test, p=0.997). Although studies have suggested that ML contain more tannins, we found that Celtis africana YL contained more CTs than did ML (matched pairs test, p=0.005), while in others there were no differences between YL and ML. Intraspecific variability in leaf HT and CT varied widely depending on individual tree sampled. For example, some trees had 10 times the amount of tannin as other individuals sampled in the same week. These results highlight the need for sampling from the same tree where monkeys are feeding and further investigations into the finer levels of primate food selection.