Supplementary information from "<b>The role of environmental factors on visual communication in Neotropical anurans</b>"

Visual signals are a widespread behavioural attribute of communication among vertebrates, often employed during intrasexual competition or mate attraction, ultimately influencing reproductive success. Despite their importance, the environmental factors driving visual signal evolution remain poorly understood. We investigated this issue in Neotropical anurans by testing how environmental factors, such as humidity and vegetation heterogeneity predict richness of species employing visual signals and signal richness. Using a dataset of 236 anuran species with documented visual signals, we conducted spatial and phylogenetic analyses using Aridity Index (AI) and Normalized Difference Vegetation Index (NDVI) as proxies of humidity and environmental heterogeneity, respectively. We analysed the data for all species collectively and subsets categorised by habit (diurnal, nocturnal) and breeding habitat (lotic, non-lotic). Our results highlight that Neotropical tropical forests harbor the greatest richness of species employing visual signals, as well as the highest signal richness. Although we observed significant correlations between visual signal distribution and environmental predictors, their explanatory power was inconsistent in both assemblage-based and cross-species approaches. We proposed that visual signals in anurans are predominantly used in water-saturated environments over shorter distances, which may explain the poor correlations with broad-scaled environmental predictors. Future studies should incorporate finer spatial scales and interpopulational variations to better determine the visual signals evolution in anurans.