Impact of climate and land cover changes on the potential distribution of four endemic salamanders in Mexico

Abstract

Anthropogenic changes, such as land use and climate change, are the greatest threats to biodiversity, especially for amphibians, which are the most endangered vertebrate class worldwide. Species distribution modelling was applied to assess how expected future climate and land cover change scenarios might influence the geographic distribution and habitat connectivity of four salamanders endemic to Mexico: Aquiloeurycea cephalica (Cope, 1865), Isthmura bellii (Gray, 1850), Pseudoeurycea robertsi (Taylor, 1939), and Pseudoeurycea leprosa (Cope, 1869). For this, the Community Climate System Model (CCSM4) with two Representative Concentration Pathways (RCP 45 and RCP 85) and two modelling methods (Maxent in ENMeval and an ensemble model in biomod2) were used. The most important environmental variables explaining the distribution of the target species, as well as the environmental niche overlap between them, were also determined. Abies forest cover was one of the most important variables explaining the current distribution of P. robertsi (contribution of 39%), P. leprosa (contribution of 18%), and A. cephalica (contribution of 22%) with a positive effect. The distribution of these three species was also limited by maximum temperatures, whereas the I. bellii distribution was more limited by minimum temperatures. The environmental niches of P. leprosa and A. cephalica were significantly similar (D = 0.637, I = 0.801, p-value = 0.02), as well as the environmental niches of P. robertsi and P. leprosa (D = 0.640, I = 0.797, p-value = 0.01). As expected, all salamander species were predicted to face a reduction in their potential distribution (reductions between 2.64 and 32.16%) and landscape connectivity (reductions between 4.93 and 73.92%) under future scenarios of climate and land cover change. Different models and scenarios were inconsistent in determining which species’ distribution would suffer the biggest reduction in the future. However, P. robertsi suffered the largest reduction in connectivity under both scenarios of climate change. Similarly, our results suggest that Sierra de las Cruces and Corredor Biológico Chichinautzin are very important areas in terms of connectivity. Unfortunately, great losses of Abies and Pinus forests were also predicted to occur in these areas between 2011 and 2014. According to these findings, the preservation of Abies forests of the Trans-Mexican Volcanic Belt is essential to preserve P. robertsi, P. leprosa, and A. cephalica salamanders, whereas the preservation of Corredor Biológico Chichinautzin and Sierra de las Cruces is essential to maintain landscape connectivity for P. leprosa, A. cephalica, and I. bellii. Thus, these areas should be prioritized in conservation programs.