Revisão sistematizada e padrões de especialização da dieta em Anura a nível global

Abstract

Post-metamorphic anurans are generalist and opportunistic mesopredators, with diets extensively described in natural history studies. However, some species and clades exhibit specialized feeding patterns, with variations in trophic niche breadth. In this context, the present study aimed to review the state of anuran diets and to understand the evolution of different diet types, investigating specialization patterns. A systematic review was conducted, extracting data from articles, including prey abundance, volume, frequency, and relative importance indices, as well as the methodologies used and the taxonomic groups studied. After standardizing the collected data, numerical (NN) and volumetric (NV) trophic niches of the species were calculated using Levins' index. Species presenting both indices simultaneously had their diets categorized into four types: A (high NN and NV), B (high NN and low NV), C (low NN and NV), and D (low NN and high NV). Based on these categories, phylogenetic mapping and ancestral state reconstructions were performed to analyze evolutionary patterns.A total of 569 articles were reviewed, with 431 focusing on natural history. A significant increase in the number of publications was observed from 2021 onward, marking the inflection point in the cumulative curve of publications per year. Geographically, most studies were conducted in Brazil, followed by the United States. The analyzed diets encompassed 584 species, with Hylidae, Leptodactylidae, and Bufonidae being the most frequently studied families. Frequently employed methods included Levins' index for trophic niche breadth, Pianka's index for prey overlap, and Jacobs' index for prey selectivity. Among the most tested hypotheses on diet variations were those related to body size and sex differences, with evidence of broader diets in certain specific groups. Evolutionarily, specialized diets (Type C) were predominant in groups such as Microhylidae, Leiuperinae, Bufonidae, Dendrobatidae, and Ceratophryidae, associated with morphological constraints, toxin sequestration, and optimal foraging theory. Significant divergences were identified, such as in Bufonidae and Leiuperinae compared to their ancestral groups. Despite geographic and taxonomic biases, the review revealed that anurans can exhibit diets distinct from the generalist and opportunistic patterns. These findings underscore the importance of investigating the ecological and evolutionary contexts of dietary specialization and standardizing methodologies to enable comparisons in future studies.