Frontiers of Biogeography

Species may respond to climate change by redistributing their distribution areas, but because they do not share the same climatic affinities, they should not respond in the same way. Consequently, distribution shifts of species that are currently found in sympatry may change the extent of the area of sympatry and therefore interspecific interactions at the local scale. In Western Europe, the green lizards Lacerta agilis and Lacerta bilineata live in partial sympatry, share morphological similarities, and can locally compete for resources. In this study, we used a correlative species distribution model (SDM), Maxent, to explore the effects of climate change on the distribution of suitable areas for each species and also within their sympatric area under future scenarios. Our simulations showed that all L. agilis subspecies are more likely to lose suitable habitats throughout their distribution areas whatever the scenario. Conversely, even if L. bilineata should lose less suitable areas, gains may be more restricted. In addition, when looking within the areas both reachable for L. a. agilis and L. bilineata to identify where sympatric areas will occur, we find that they should be spatially restricted. Climatic refugia potentially shared for both lizards may therefore be limited. Consequently, competitive exclusion expected in areas suitable for both species (i.e., the potential area of sympatry) could decrease in the future as climate changes likely lead L. agilis subspecies and L. bilineata to follow different species range shifts trajectories over the 21st century.