O’GRADY, S; MORANDO, M; AVILA, L; DEARING, M/D; University of Utah; Brigham Young University; Brigham Young University; University of Utah: Correlates of herbivory in the lizard sub-family Liolaeminae

Distinct differences in gut structure and function exist in herbivores and carnivores. Despite showing morphological differences between digestive strategies, most comparative studies highlighting specializations are confounded by phylogeny through the use of distantly related species. We investigated gut specializations for herbivory with the lizard sub-family Liolaeminae. The large number of species and wide range of diet strategies in Liolaeminae make it well suited for phylogenetically independent comparisons of dietary correlates. We classified and compared the dietary strategies and gut morphology of 204 individuals from 31 species in Liolaeminae. Additionally, the presence and location of nematodes in the gut were compared among species. Herbivorous species were larger (SVL) than omnivores and insectivores, but even after controlling for body size, herbivores had larger guts. The small intestine and large intestine were 2X longer in herbivores than in omnivores and insectivores. Furthermore, the large intestine was 3X more voluminous in herbivorous species than omnivores and insectivores. In addition to a larger gut, herbivorous species had significantly more nematodes in the colon than omnivores or insectivores. Herbivorous species in Liolaeminae lacked both a cecum and colonic folds, which are common in herbivorous iguanids. In herbivores that lack many of the apparent specializations for herbivory, an enlarged gut and colonic nematodes may increase the efficiency with which plant matter is digested.