A first approach to evaluate the vulnerability of islands’ vertebrates to climate change in Mexico

Mexican islands are one of the most diverse territories in the world and consequently their conservation should be a national and international priority. Three main threats to islands’ diversity have been detected: invasive species, land use change and climate change. Most studies have been focused on invasive species and land use change. Actually, as far as we know, this work is the first approach to evaluate climate change impacts on the biodiversity of islands in Mexico. We had two main goals: to list the vertebrate species that have been registered in Mexican islands and to model the possible impacts of climate change in the distribution of islands’ vertebrates. To evaluate climate change impacts, we used the ecological niche modeling that relates geographic occurrences with environmental variables to create a bioclimatic profile that can be projected in other time and other geographic areas. In our results we obtained a list of species registered in Mexican islands that increased in more than twice the number of species acknowledged by the Mexican government and the ecological niche modeling of 54 vertebrate species. We found that the species list effort was very important, because knowing which species exist is the first step to preserve them. In terms of ecological niche modeling, we modeled mammals, reptiles and amphibians. From these three groups, reptiles were the group with greatest losses and more species in the top-ten vulnerable list. If we considered a no dispersion scenario, all evaluated species presented losses regarding their current potential distribution area. If the full dispersion scenario was taken into account, the net change value resulted positive for the majority of the species evaluated, consequently if no barriers exist and the dispersion ability is good enough, changes in climatic conditions might not be an important threat. However, this is not the case for most species evaluated. Areas with a higher number of species (richest areas) do show changes in the future with shifts to the east and north of the country. Finally, we could find significant differences between times and scenarios in terms of suitable area losses. Greatest losses can be found in the long term RCP 8.5 Wm –2 in comparison to the long term RCP 4.5 Wm –2 , meaning that the direction that humanity takes in terms of climate change will have consequences on island biodiversity. In this work, we did not take into account the sea level rise, which is expected to have important impacts on islands species.