Dietary composition and selection in the stream-breeding anuran assemblage from a tropical wet forest in eastern Mexico

Abstract

In this study, we analyzed seasonal variation in dietary composition and diversity, structure along the trophic axis, and prey selection in a stream-breeding anuran assemblage from Mexico. It is composed of four morphologically diverse species: three strictly arboreal (Hyalinobatrachium fleischmanni, Ptychohyla zophodes, and Rheohyla miotympanum) and one that occupies several microhabitats (Lithobates vaillanti). Dietary composition did not differ between seasons, but it differed among the four species. Araneae, Orthoptera, Homoptera, and Lepidoptera (adults) were the prey that accounted for most of the variation. Dietary diversity was higher in the dry than in the rainy season in L. vaillanti, and was higher in this species than in the other three. In the dry season, arthropods were more abundant but less diverse in the environment, and L. vaillanti and R. miotympanum consumed less prey than in the rainy season. Furthermore, we detected that the frog assemblage was nonrandomly structured only in the dry season. Hyalinobatrachium fleischmanni strongly selected Homoptera and Orthoptera, but did not select prey by their size within the size range consumed. Ptychohyla zophodes and R. miotympanum strongly selected Lepidoptera (adults and larvae) and selected their prey by their size in the dry season. Our results overall suggest that interspecific competition could be a strong force in shaping type and quantity of food consumed between the two hylids. Additionally, we found a wider array of microhabitats used and prey types consumed than previously reported for L. vaillanti. Lastly, the relatively specialized diet of the three strictly arboreal species, and their selection towards insects sensitive to habitat changes (homopterans and lepidopterans), make them particularly vulnerable to changes in arthropod communities.