The best way to reduce problems related to invasive species is by preventing introductions into potentially susceptible areas. The purpose of this study was to create distribution models for the invasive gastropod Achatina fulica Bowdich, 1822 in South America in order to evaluate its potential geographic distribution and identify areas at potential risk. This mollusc, considered one of the 100 world's worst invasive alien species, is the focus of intense concern due to its impact on agriculture, human health, and native fauna. We tested two commonly used ecological niche modeling methods: Genetic Algorithm for Rule-Set Prediction (GARP) and Maximum Entropy (MaxEnt). Models were run with occurrence points obtained from several sources, including the scientifi c literature, international databases, governmental reports and newspapers, WorldClim bioclimatic variables, and altitude. Models were evaluated with the threshold-independent Receiver Operating Characteristic (ROC) and Area Under the Curve (AUC). Both models had consistent performances with similar areas predicted as susceptible, including areas already affected and new potentially susceptible areas in both tropical and temperate regions of South America.
Dinoflagellates of the genus Ceratium are predominantly found in marine environments, with a few species in inland waters. Over the last decades, the freshwater species Ceratium hirundinella and Ceratium furcoides have colonized and invaded several South American basins. The purpose of this study was to create a distribution model for the invasive dinoflagellate C. furcoides in South America in order to further investigate the basins at potential risk, as well as the environmental conditions that influence its expansion. This species is known to develop blooms due to its mobility, resistance to sedimentation, and optimized use of resources. Although nontoxic, blooms of the species cause many problems to both the natural ecosystems and water users. Potential distribution was predicted by using a maximum entropy algorithm (MaxEnt). Model was run with 101 occurrences obtained from the scientific literature, and climatic, hydrological and topographic variables. The developed model had a very good performance for the study area. The most susceptible areas identified were mainly concentrated in the basins between southeastern Brazil and northeastern Argentina. Besides already affected regions, new potentially suitable areas were identified in temperate regions of South America. The information generated here will be useful for authorities responsible for water and watershed management to monitor the spread of this species and address problems related to its establishment in new environments.
Many land snails are vulnerable to climate change as a consequence of small distribution ranges and poor dispersal. South America is a diverse region in terms of land snail fauna, but studies about the impacts of climate change on molluscan biodiversity are virtually nonexistent. Bioclimatic models provide an important tool to assess how habitat suitability may change in a warming planet. In this study, we examine potential impacts of climate change on a giant land snail (Megalobulimus sanctipauli) from the Atlantic Forest to predict future shifts in its potential distribution, and to identify protected areas that may contain suitable habitat for setting conservation priorities. Using a maximum entropy algorithm, we modeled the species' potential distribution across South America under current climatic conditions and projected the results onto two climate change scenarios for two time frames. A 2.17 % of South America on the Atlantic Forest was predicted to be currently suitable for the species, comprising the border area among Argentina, Brazil and Paraguay. Prognosis of future distribution showed a trend to a northern retraction, but a southern expansion of current potential range. More than 150 protected areas were identified to contain climatically suitable habitat for the species, but on the less optimistic outlook only~1545 km 2 of protected areas (0.009 % of South America) would remain suitable for the species by the end of the century. Our findings are expected to improve understanding of climate change impacts on native giant land snails and to contribute in conservation efforts on this malacofauna.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.