03.Diet composition and tropic niche overlap of Ameivula ocellifera Spix 1825 (Squamata: Teiidae) and Tropidurus cocorobensis Rodrigues 1987 (Squamata: Tropiduridae), sympatric species with different foraging modes, in Caatinga

Abstract

Lizard diets can be influenced by several factors, such as age, physiological aspects, food availability, behaviour and foraging mode. The latter can be an important predictor of the type of prey consumed. This study analysed Ameivula ocellifera and Tropidurus cocorobensis diets, both of which are psammophiles and coexist in an area of Caatinga in north-eastern Brazil, but use different foraging modes. Lizard stomachs were examined, and prey categories were quantified by frequency of occurrence, number, volume and relative importance index. We used PERMANOVA and SIMPER analyses to understand the dissimilarities among diets. Additionally, we estimated the degree of trophic niche overlap between species using the Pianka index. The most frequently consumed food item by A. ocellifera was Isoptera and Formicidae (Hymenoptera) for T. cocorobensis. The trophic niche overlap between the species was approximately 0.24 and, although there were many consumed prey categories in common, the proportion at which these prey categories were consumed was quite divergent. For example, the consumption of plant material, which was present in the diet of both species, was much more important for T. cocorobensis compared to the active forager A. ocellifera. Our results indicate that despite sharing the same space and consuming the same prey types, these species have significant differences in their diets. Furthermore, these divergences can be explained by several factors in the environment and even by the evolutionary history of each species, which are included in different families and are not evolutionarily close to each other. Keywords: diet; niche overlap; foraging mode; plant consumption; competition