Biogeographic regionalization of the Amazon using highly diverse horse flies (Diptera: Tabanidae): insights from three decades of data

ABSTRACTDelimiting biogeographic regions based on occurrence data is an interesting approach to investigating processes behind biodiversity distribution patterns. Comparing spatial scales and identifying predictor variables of biogeographic regions have wide application for biodiversity conservation. In this study we used a comprehensive database containing more than thirty years of horse fly records to estimate species richness, endemism, and species composition, and regionalize the Amazon biogeographically. We compared five spatial scales defined by grid size (1–5º), and test five hypotheses (elevation, climate, vegetation cover, and two regionalizations from the literature) to identify predictors of the biogeographic regions. Endemism, species richness and composition were predicted by different sets of predictor variables, although the models were highly dependent on spatial scale. We identified three well-defined biogeographic regions, which have been formed by a combination of geographic distance, climate and historical factors converging with some theories proposed for mammals. Our models indicated dispersal as a key factor for regionalization, as it can be constrained by a combination of climate and historical processes changing habitats over time, although this finding was highly dependent on spatial scale. We showed that horse flies are interesting models for biogeography although they have been historically neglected.KEYWORDS: EndemismNeotropicsspatial scalespecies compositiontabanid AcknowledgmentsWe thank all the curators of the entomological collections visited, the Instituto Nacional de Pesquisas da Amazônia for the logistical support in the expeditions, and Professor Francisco Xavier (Chico) for technical support.Disclosure statementNo potential conflict of interest was reported by the author(s).Supplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/01650521.2023.2254505Additional informationFundingALH thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support (Programa Ciências Sem Fronteiras, grant number [246878/2012-6]), ‘Ação transversal: Redes Regionais de Pesquisas em Biodiversidade e Tecnologia’, grant number 79/2013 grant number [407627/2013-8], project ‘Biodiversidade de Insetos na Amazônia-Rede BIA’ and Fundação de Amparo à Pesquisa do Estado do Amazonas, Edital Universal grant number [0002/2018], Project ‘Tabanidae da Amazônia: Taxonomia e Diversidade’. TKK and DDDC thanks to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the scholarship granted (grant numbers [310214/2021-1] and [151354/2022-7], respectively).