Climate and land use change through the eyes of two endemic amphibians: Temporal trajectories of suitability and connectivity reveal differential responses

Abstract

Climate and land-use change are expected to cause habitat loss and fragmentation, conditioning the ability of a species to ultimately persist in a territory. Amphibians are particularly sensitive to such threats due to their life-history traits and small-ranged distributions. Reconstructing how each factor has contributed to the historical trajectories of change in landscape suitability and connectivity, and which process is prevailing (loss or fragmentation) becomes pivotal to plan conservation and mitigation actions at local scale. By combining habitat suitability modelling and circuit- and graph-theory, we determined the temporal change in habitat suitability, functional connectivity, and spatial ecological network functionality for two Italian endemic amphibian taxa, an urodele, the Italian alpine newt, and an anuran, the Apennine yellow-bellied toad. The temporal trajectories for the alpine newt showed a gradual loss of suitability and functional connectivity, which is predicted to continue in the future, but with a steep drop in the network functionality already occurred in the last thirty-year period. This suggests that restoring connectivity may be the key for conservation actions of this endemism. Differently, in the Apennine yellow bellied toad, we found that the spatial network has already collapsed, while future projections highlighted a huge habitat loss issue. Conservation efforts for this species should therefore be focused on preserving current suitable areas and identifying possible translocation sites where to settle new populations. The approach we proposed is highly generalizable and can be updated to include alternative scenarios and simulated conservation actions, providing stakeholders with a target-defined prioritization.