Habitat amount drives the functional diversity and nestedness of anuran communities in an Atlantic Forest fragmented landscape

Abstract

Natural environments disturbed by human activities can suffer from species extinctions, but some can still harbor high taxonomic diversity. However, disturbances may have impacts beyond the species level, if the species lost represent unique functions in the ecosystem. In this study, we evaluated to what extent the amount of habitat can determine the functional diversity and nestedness of amphibian communities in an Atlantic Forest fragmented landscape in Brazil, and if there is a threshold of habitat amount beyond which there is severe loss of functional diversity. As species responses may depend on their habitat type, we performed the analyses for three different sets of species: all species, forest‐dependent species, and generalist species. We also evaluated the relative importance of turnover and nestedness components to total functional dissimilarity among sites. Habitat amount affected functional diversity of frogs, especially for forest‐dependent species where a linear reduction was detected. The functional dissimilarity among sites was mostly explained by the nestedness component. The reduction of functional diversity was mediated by an ordered loss of traits, leading to a functionally nested metacommunity. These sensitive traits were closely related to habits and reproductive modes that depend on rivers and streams. The maintenance of functional diversity of frogs in fragmented landscapes must rely on the conservation of both terrestrial and aquatic environments, as some species and their traits can disappear from remnants of native vegetation lacking some specific habitats (e.g. streams). Abstract in Portuguese is available with online material.

A meta‐analysis of the effects of fragmentation on the megadiverse herpetofauna of Brazil

“…These patterns have also been reported among diverse species of the Brazilian herpetofauna, in both forest and non-forest biomes (Almeida-Gomes et al, 2019;Moreira et al, 2016;Palmeirim et al, 2017). Another limitation of our analysis is the possible existence of spatial autocorrelation in the responses of the species included in the same study, which can bias the significance rates of statistical tests (Dale & Fortin, 2009).…”

Random placement models explain species richness and dissimilarity of frog assemblages within Atlantic Forest fragments

“…While generalist species are known to tolerate a broader range of environmental conditions, specialist (e.g. forest‐dependent) species are more dependent on specific environments for survival or reproduction (Almeida‐Gomes & Rocha, 2015; Almeida‐Gomes et al., 2019; Devictor et al., 2008; Morante‐Filho et al., 2016; Pardini et al., 2010). As a result, generalist species tend to occupy more sites and be more abundant than specialists (Brown, 1984).…”

“…Alternatively, a better fit of the area‐based model could indicate the presence of niche processes associated to patch area, such as habitat diversity. As species with different habitat requirements may respond differently to niche and neutral processes (Almeida‐Gomes et al., 2019; Morante‐Filho et al., 2016), we also tested these predictions separately for forest‐dependent and habitat‐generalist species.…”

Habitat amount and ambient temperature dictate patterns of anuran diversity along a subtropical elevational gradient

“…This provides direct support for the habitat amount hypothesis (HAH; Fahrig, 2013), rather than the more general species–area relationship. The HAH was also found to be important in predicting taxonomic diversity in small mammals and functional diversity in frogs in highly fragmented Atlantic Forest landscapes (Almeida‐Gomes et al., 2019; Vieira et al., 2018).…”