Trophic Ecology of Leptodactylus elenae Heyer, 1978: An Analysis throughout Its Post-Metamorphic Development

Abstract

Diet is a fundamental attribute in the life history of any organism: knowledge of its composition and the strategies used by predators to capture their prey is essential to understand competitive interactions and the predator-prey dynamics that have an impact on community organization. We studied the trophic ecology of Leptodactylus elenae and obtained more information about the composition of its diet, diversity, amplitude, and overlap of thetrophic niche for the total population and between size classes. In addition, we calculated the degree of individual specialization in order to test whether diet breadth is the result of the sum of specialist individuals using small subsets of the population niche or, conversely, to generalist individuals with ample use of the resource. The individuals were collected using a system of live pitfall traps located in a partially urbanized area in Corrientes province, Argentina.Diet samples were obtained by stomach flushing technique. Individuals were grouped into three size classes. Sixty-three individuals had verifiable stomach contents (Class I = 34, Class II = 15, and Class III = 14). Eighteen categories of prey were identified, with numerical and volumetric predominance of coleopteran and insect larvae, which were also the most consumed. Diversity and evenness of prey in the diet was calculated and accumulation curves of prey items were used to evaluate representativeness (efficiency) of the samples. The overlap of trophic niches was high between the three classes, indicating that there were no differences in the numerical and volumetric composition of their prey. The degree of individual specialization was high and tended to be greater in spring than in summer. Leptodactylus elenae is a generalist predator with a high degree of individual specialization not attributable to morphological changes or seasonality. This study contributes to increasing the information on the diet of this species and raises questions for future studies.