Diet evolution in litter frogs: reassessing the Toft’s hypotheses

Abstract

In a series of papers starting in the early 1980s, Toft proposed a general scenario to explain dietary evolution in leaf litter anurans in which species would “form a continuum from those that specialize on ants and mites, through generalists, to species that avoid ants and mites”, and these differences would in turn correlate with foraging strategies, morphology, and defense mechanisms. In this study, we reassess this hypothesis using a global dataset on the dietary composition of 120 anuran species. Surprisingly, we found that the relative contribution of ants and mites in anuran diets were largely orthogonal to one another. Moreover, we did not find evidence for the continuum of dietary composition envisioned by Toft. These results suggest that, although ants and mites have played a major role in the evolution of aposematic species, the trends found in those species might not be directly extrapolated to all leaf litter anurans.

The roles of anurans in antagonistic networks are explained by life‐habit and body‐size

“…2012; Nadaline et al . 2019), and the forest floor is full of a great diversity of prey (Becker et al . 2007; Rafael et al .…”

“…Foraging for food also increases the chances that an anuran encounters infective stages of parasites in the environment which are transmitted by physical contact (Campião et al 2016). As the diversity in amphibian's diet is heavily influenced by prey availability (Anderson et al 1999;López et al 2009López et al , 2015Falico et al 2012;Nadaline et al 2019), and the forest floor is full of a great diversity of prey (Becker et al 2007;Rafael et al 2012), anurans with terrestrial habits may encounter great variability of prey, and hence are more susceptible to a greater richness of parasite infections, as also found by Euclydes et al (2021).…”

“…We expect modular networks, as antagonist interactions tend to form specialized interaction networks (Durán et al 2018), and that specialized network leads to modularity (Dormann & Strauss 2014). Also, the role of anurans as predators will be related to their habit, as the availability of prey is associated with their diet choices (Nadaline et al 2019;Michelin et al 2020), and the anuran habit can predict what is preyed upon, as they are generalist predators (Vignoli & Luiselli 2012). Conversely, we expect larger anurans to play a central role in the parasite-anuran network since larger anurans can host a greater diversity of parasites (Campião et al 2015), and consequently share more connections with other anurans.…”

“…Also, the role of anurans as predators will be related to their habit, as the availability of prey is associated with their diet choices (Nadaline et al . 2019; Michelin et al . 2020), and the anuran habit can predict what is preyed upon, as they are generalist predators (Vignoli & Luiselli 2012).…”