O POTENCIAL EFEITO DAS MUDANÇAS CLIMÁTICAS SOBRE A COMPETIÇÃO DE ESPÉCIES NATIVAS E EXÓTICAS DE MOLUSCOS SUL-AMERICANOS

Abstract

Currently, there is an intense loss of biodiversity all over the world, causing serious problems to Humanity. There are several factors that contribute to the loss of biodiversity, such as the loss and fragmentation of habitats and global climate change. Climate change is responsible for several changes in abiotic characteristics of environments that cause several ecological problems, such as favoring the invasion of exotic species. Invasion by exotic species can cause numerous damages to the local economy, such as crop losses, forestry itself and even damage to pastures. With the current availability of species occurrences and climatological data, species distribution models began to be used to test processes in macroecology, such as niche evolution in invasion events in climate change scenarios. With the distribution models, it was possible to correlate species occurrences with climatic information to create a multivariate environmental space. Among the hundreds of invasive species, one species that stands out is the giant African snail, Achatina fulica. In our Brazilian fauna we have one of the most distinct groups in the region, the endemic giant snails of the genus Megalobulimus. In this context, this work aims to evaluate the potential effects of A. fulica on native species of molluscs of the genus Megalobulimus, in a perspective of potential ecological competition between such species on macroecological scales. Furthermore, this work intends to evaluate the potential effect of the biological invasion of A. fulica on native species in a context of future climate change. Geographic coordinates that indicate the occurrence of the species were obtained in online databases and in the literature. Soon after, they were treated in order to maintain the reliability of the models. Nineteen climatic variables from WordClim were considered. The procedures were performed in the R software and the models were tested with partitions of 70% for training and 30% for testing. We performed the t test for dependent samples, in order to observe the overlap of native species with A. fulica in the present and future scenarios and the D metric was used to measure the niche overlap. A total of 2,725 occurrence points were obtained, being 2,493 of the invasive exotic species A. fulica and 232 of the 10 native species of the genus Megalobulimus. The average of the Jaccard value of all species was 0.72 considered good, indicating that the generated models are reliable. We have seen that populations of the invasive alien species occupy areas with conditions that are also occupied by native species. For the future, it is possible that there will be a small decrease in the areas of suitability for the species A. fulica.