Human actions have caused the fragmentation of natural vegetation, habitat loss and climate change. The Cerrado, considered one of the global hotspots of diversity, has suffered great habitat loss due to these factors, which has been aggravated by the agricultural expansion that took place during the last 60 years. In this context, we chose species of the genus Eugenia L. (Myrtaceae) occurring in the Brazilian Cerrado to describe richness patterns and range loss, and determine conservation priorities for the Cerrado. Ecological niche models (ENMs) were applied to calculate the geographical range of each species in the past (Last Glacial Maximum – LGM, 21 000 years ago), present (PIP, representing current climatic conditions – 1760 years ago) and future (near future – NF, 2080–2100). These results were combined to calculate the richness of the group and also to estimate the range loss of these species in the future. Moreover, we evaluated the irreplaceability of areas for species conservation, aiming to maximize the biotic stability of Eugenia species. Our results showed that the highest species richness in the past was found in the southwestern region of the Cerrado and, currently, the richest regions are found in the central and southeastern areas. However, in the future, we predict a shift of the greatest values of richness towards the southeastern region, an area currently occupied by the Atlantic forest. Although areas with high conservation priorities were found scattered across the biome, this shift is worrisome due to the high fragmentation rate and intensive human occupation thoughout the Atlantic region. Thus, conservation efforts should focus on areas found within these limits.
RESUMO. Neste estudo, usamos dois tipos de modelagem de distribuição de espécies (correlativo e mecanístico), com o objetivo de avaliar o efeito das mudanças climáticas sob a distribuição geográfica de Rhinella granulosa (Spix, 1824), espécie inserida principalmente no bioma Caatinga. Avaliamos a predição, levantada por outros autores, de que espécies de anfíbios distribuídos em climas quentes terão suas distribuições espaciais restringidas por aumento da temperatura considerando cenários futuros. Na abordagem correlativa, os resultados mostraram que as distribuições espaciais geradas pelo modelo de distância Euclidiana foram mais conservativas, ou seja, as áreas que apresentaram menor distância do nicho ótimo se restringiram às áreas de distribuição real da espécie (Caatinga) e às pequenas regiões que abrangem o bioma Cerrado. A abordagem mecanística apresentou resultados menos conservativos, onde o habitat indicado como adequado para R. granulosa está contido em grande parte da América do Sul, formando uma extensa área contínua. No geral, verificou-se que R. granulosa não sofrerá forte influência climática sobre sua distribuição geográfica no futuro, pelo menos até 2080, provavelmente por apresentar uma fisiologia extremamente tolerante às altas temperaturas e por possuir adaptações para suportar clima quente e seco. PALAVRAS-CHAVE.Modelagem de distribuição de espécies, tolerância termal, modelo correlativo, modelo mecanístico.ABSTRACT. Potential effects of climate change on the distribution of a Caatinga's frog Rhinella granulosa (Anura, Bufonidae). In this study, we used two types of species distribution modelling (correlative and mechanistic) in order to evaluate the effects of climate change on the geographic distribution of Rhinella granulosa (Spix, 1824), distributed in the Caatinga biome. We tested the prediction that amphibians distributed in warm weather will have their spatial distribution constrained by high temperatures in the future. Using the correlation approach, we observed that the potential distribution generated by Euclidian Distance showed more conservative areas (e.g. with a smaller distance from optimum niche) limiting it to the current distribution of the species (e.g. Caatinga), and to small areas in the Cerrado biome. The mechanistic approach showed a less conservative result, in which the habitat indicated as suitable for R. granulosa comprised a large extension of South America, encompassing a contiguous area. In general, we observed that the spatial distribution of R. granulosa would not be strongly affected by climate change, at least until 2080. Probably, this species has a tolerant physiology to high temperatures and shows adaptations that support dry and hot weather.
The world is passing through abrupt climate changes that are a threat for biodiversity. Stryphnodendron adstringens (Mart.) Coville (Fabaceae) is a tree species endemic to the "Cerrado" biome with a high economic potential. Its exploitation is done in an extractive way, which, coupled with climate changes and other landscape changes, can contribute to its decline. Here, we use ecological niche modeling (ENM) to map its distribution and environmental suitability in the past, present and future climates. The environmental variables were derived from community climate system model, for present, past and future scenarios. The maps showed that the specie had a larger distribution area in the past, during the last glacial maximum, and it decreased mainly in the Amazon rainforest region; today, the species is found mainly in the center of "Cerrado." For the different climatic scenarios predicted for the future and considering various levels of anthropogenic drivers for climate change, a drastic loss of climatically suitability area of S. adstringens is expected, which may compromise the viability of the species. Our ENMs can then be useful to better establish and delimit conservation actions for this important species in the "Cerrado" region.
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