Climate Change and the Distribution of Neotropical Red-Bellied Toads (Melanophryniscus, Anura, Amphibia): How to Prioritize Species and Populations?

We used species distribution modeling to investigate the potential effects of climate change on 24 species of Neotropical anurans of the genus Melanophryniscus. These toads are small, have limited mobility, and a high percentage are endangered or present restricted geographical distributions. We looked at the changes in the size of suitable climatic regions and in the numbers of known occurrence sites within the distribution limits of all species. We used the MaxEnt algorithm to project current and future suitable climatic areas (a consensus of IPCC scenarios A2a and B2a for 2020 and 2080) for each species. 40% of the species may lose over 50% of their potential distribution area by 2080, whereas 28% of species may lose less than 10%. Four species had over 40% of the currently known occurrence sites outside the predicted 2080 areas. The effect of climate change (decrease in climatic suitable areas) did not differ according to the present distribution area, major habitat type or phylogenetic group of the studied species. We used the estimated decrease in specific suitable climatic range to set a conservation priority rank for Melanophryniscus species. Four species were set to high conservation priority: M. montevidensis, (100% of its original suitable range and all known occurrence points potentially lost by 2080), M. sp.2, M. cambaraensis, and M. tumifrons. Three species (M. spectabilis, M. stelzneri, and M. sp.3) were set between high to intermediate priority (more than 60% decrease in area predicted by 2080); nine species were ranked as intermediate priority, while eight species were ranked as low conservation priority. We suggest that monitoring and conservation actions should be focused primarily on those species and populations that are likely to lose the largest area of suitable climate and the largest number of known populations in the short-term.

本研究采用物种分布模型（species distribution modeling），探究气候变化对24种新热带区黑爪蟾属（Melanophryniscus）无尾两栖类的潜在影响。该属蟾蜍体型小巧、迁移能力有限，且多数物种处于濒危状态或地理分布范围狭窄。我们分析了所有物种分布范围内适宜气候区域的面积变化，以及已知发生位点的数量变化。本研究采用最大熵（MaxEnt）算法，针对每个物种预测了当前及未来的适宜气候区域（采用政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）的A2a与B2a情景共识方案，时段涵盖2020年与2080年）。到2080年，40%的物种可能丧失超过50%的潜在分布区，而28%的物种潜在分布区丧失比例将不足10%。有4个物种的当前已知发生位点中，超过40%将位于2080年的预测适宜区域之外。气候变化（即适宜气候区域缩减）的影响效应，与研究物种当前的分布面积、主要生境类型或系统发育类群均无显著关联。本研究基于各物种适宜气候范围的预估缩减幅度，为黑爪蟾属（Melanophryniscus）物种划定了保护优先级等级。其中4个物种被列为高保护优先级：M. montevidensis（到2080年或将完全丧失原有适宜分布范围及所有已知发生位点）、M. sp.2、M. cambaraensis以及M. tumifrons。另有3个物种（M. spectabilis、M. stelzneri及M. sp.3）被列为高-中优先级（到2080年适宜分布区预估缩减幅度超60%）；9个物种为中优先级，剩余8个物种被列为低保护优先级。本研究建议，短期监测与保护行动应优先聚焦于那些可能丧失最大面积适宜气候区域、以及最多数量已知种群的物种与种群。