Digestive ecology of two omnivorous Canarian lizard species (Gallotia, Lacertidae)

Abstract

Omnivorous endemic Canarian lacertids (Gallotia atlantica and G. galloti) do not present any specific digestive and physiological adaptations to herbivorous diet, compared to species and populations with a different degree of herbivory in the Canarian archipelago. The only characteristics that could be related to the type of diet were the number of cusps per tooth (between species) and the number of small stones contained in droppings (between species and populations). The rest of measured traits were correlated with lizard size and for this reason G. galloti has longer intestines, heavier stomachs and livers, more teeth and cusps, and longer gut passage. These data suggest that body size is a major determinant of the reliance on plant food (mainly fleshy fruits) in these lizards and facilitates mutualistic interactions with fleshy-fruited plant species.