It's not easy eating green: physiological and microbial adjustments allow herbivory in an omnivorous lizard

KOHL, KEVIN D.; BRUN A; MAGALLANES, MELISA; LASPIUR, ALEJANDRO; ACOSTA, JUAN CARLOS; BORDENSTEIN, SETH R.; CAVIEDES-VIDAL E

Portland Oregon

Congreso; SICB Annual Meeting; 2016

Society for Integrative and Comparative Biology

While herbivory is a common feeding strategy in a number ofvertebrate classes, less than 4% of squamate reptiles feed primarilyon plant material. It has been theorized that physiological ormicrobial limitations may constrain the evolution of herbivory inlizards. Herbivorous lizards exhibit adaptations in digestivemorphology and function that allow them to better assimilate plantmaterial. However, it is unknown whether these traits are fixed orperhaps phenotypically flexible as a result of diet. Here, wemaintained a naturally omnivorous lizard, Liolaemus ruibali, on amixed diet of 50% insects and 50% plant material, or a plant-rich dietof 90% plant material. We compared parameters of digestiveperformance, gut morphology and function, and gut microbialcommunity structure between the two groups. We found that lizardsfed the plant-rich diet maintained nitrogen balance. Additionally,lizards fed the plant-rich diet exhibited significantly longer smallintestines and larger hindguts compared to those fed the mixed diet,demonstrating that gut morphology is phenotypically flexible.Lizards fed the plant-rich diet harbored small intestinal communitiesthat were more diverse and enriched in Melainabacteria andOscillospira compared to mixed-fed lizards, taxa that are associatedwith fermentation. Additionally, the relative abundance ofsulfate-reducing bacteria in the small intestine significantlycorrelated with whole-animal fiber digestibility. Thus, wehypothesize that physiological and microbial limitations do notconstrain the evolution of herbivory in lizards.42