Species richness, range size, and wing development in South American melanopline grasshoppers (Orthoptera, Acrididae)

Abstract

1. Wing development can influence biogeographic patterns, and much debate has been focused on the ecological conditions that favour secondary wing reductions in insects. Although grasshoppers are mostly flight-capable, brachypterism appears to be common in many species and has been typically associated with limited dispersal abilities. 2. This study presents the first comprehensive analysis of biodiversity patterns in South American melanopline grassshoppers. Two different macroecological methodologies were applied: a range–diversity plots approach and generalised lineal models (GLMs). The study simultaneously considered three features (species richness, range size, and wing development) and four potentially explanatory hypotheses that can influence geographic biodiversity patterns: energy, environmental heterogeneity, seasonality, and habitat suitability hypotheses. 3. These analyses of dispersal abilities and distributional data indicate a clear and consistent association between wing development and biogeographical patterns in South American melanopline grasshoppers. Brachyptery was related to small distribution sizes, whereas the opposite was true for macroptery. Melanopline species richness is best explained by all the environmental hypotheses considered in the analysis (energy, environmental heterogeneity, seasonality, and habitat suitability hypotheses), whereas geographic range size is explained by the environmental heterogeneity and seasonality hypotheses. 4. Models indicate a stronger association with range size than with species richness, and it is therefore considered that range size is a key feature to elucidate the spatial patterns of biodiversity. Despite the relevance of species richness and range sizes as descriptors of macroecological and biodiversity patterns, these features are seldom investigated simultaneously.