PADRÃO DE DISTRIBUIÇÃO E ADEQUABILIDADE DE DUAS PATATIVAS (THRAUPIDAE: Sporophila) E BRAQUIÁRIAS NA AMÉRICA DO SUL

Abstract

The introduction of invasive alien species is one of the main causes of extinction of native species, species with high invasive potential are able to alter the natural characteristics of occupied environments to an ecosystem level. The responses of invasive species to climate change according to their phenological, genetic and behavioral characteristics. The invasive exotic plants of the genus Urochloa are highlighted as threats to country birds. The seedeaters (Sporophila plumbea and Sporophila beltoni; Passeriformes: Thraupidae) are birds adapted to feed the fruits of these grasses. Both birds are commonly addressed in comparative studies because of a recent association of impact and phylogenetic association, but there are no ecological niche comparisons with invasive exotic grasses. In this way, we aim to compare the predictive distribution of the two species of seedeaters mentioned above and Urochloa spp. in South America under the influence of global climate change. We collect occurrences for species in online databases and exclude those that are doubtful, biased or missing information. As 19 environmental variables were removed from the WorldClim standardized and subjected to an analysis of the main components. For future projection, we use 17 Atmospheric-Ocean Climate Change Models, considering the most pessimistic scenario of carbon emissions (RCP, 8.5). For training and testing of models we use the checkboard method and training subset had its performance restricted to the ecoregions of South America. For model evaluation, quantification of commission errors and omission through the Jaccard similarity index. For building the models we use the ENMTML package, in R software with eight modeling algorithms. The pseudo-absences were allocated in a multivariate climatic space using Bioclim and the final models produced were concatenated into a single final model using the ensemble method. It obtains 887 records for Urochloa spp., 675 for S. plumbea and 44 for S. beltoni, and Jaccard values equal to 0.88; 0.79 and 0.74; respectively. The models were able to predict new areas of suitability for the species. In future scenarios, the species S. beltoni showed total loss of suitability in the areas currently habitable, while S. plumbea presented an isolation of the patches currently suitable. Approximately 60% of the territory of South America is suitable for invasion by Urochloa spp. and there was a high overlap of areas (90%) between both birds and exotic. We have shown that the most favorable areas for the establishment of birds are under the potential threat of invasive exotic grasses of the genus, so the invasive genus has proved to be a threat to both bird species, both in the current scenario and under the effect of future climate changes.