1Department of Biology, University of Southern California, 2Environment Agency, England, 3Institute for Population Genetics, University of Veterinary Medicine, Vienna
Saturday All day, Park Concourse
Many plants contain toxic secondary compounds, such as polyphenols, and structural carbohydrates, like cellulose, to deter herbivores. Herbivores can alter their behavior to reduce their ingestion of these plant defenses. By consuming plant parts containing smaller amounts of these compounds, selective herbivores can maximize the digestibility of their food.
We studied the dietary polyphenol and cellulose of two sympatric lemurs, the ring-tailed lemur (Lemur catta), a generalist herbivore, and the folivorous Verreaux’s sifaka (Propithecus verreauxi) in Beza Mahafaly special reserve, Madagascar. Both species’ diets shift seasonally between the wet and dry seasons. We hypothesized that the polyphenol and cellulose content of P. verreauxi’s diet would remain stable across seasons, while these would decrease from the dry to the wet season in L. catta from the fluctuating availability of fruit. We also predicted that these levels would be higher in P. verreauxi than L. catta year-round due to their folivorous diet.
We observed the lemurs and recorded the contribution of each food to their diet. By measuring the polyphenols and cellulose in each food, we were able to calculate their total intake of these compounds. Contrary to expectations, we found an increased intake of polyphenols in both species in the wet season, due to the increased availability of a few key foods. Each lemur species preferred different polyphenol-rich foods, leading to a timing gap between their peak polyphenol consumption due to the availability of these foods. These results can help us understand how plant chemical defenses influence diet choice in herbivores.
This study was funded by the National Scientific Foundation.