Comparative genetic and demographic responses to climate change in three peatland butterflies in the Jura massif

Climate is a main driver of species distributions, but all species are not equally affected by climate change, and their differential responses to similar climatic constraints might dramatically affect the local species composition. In the context of climate warming, a better knowledge of the ability of dispersal-limited and habitat-specialist species to track climate change at local scale is urgently needed. Comparing the population genetic and demographic impacts of past climate cycles in multiple co-distributed species with similar ecological requirements can help predicting their future response to climate warming, but such comparative studies remain rare. Here, we studied the relationship between demographic history and past changes in spatial distribution of three protected peatland butterfly species (Boloria aquilonaris, Coenonympha tullia, Lycaena helle) in the Jura massif (France), using a genomic approach (ddRAD sequencing) and species distribution modeling (SDM). We found that these species have a similar and narrow thermal niche, and share a common demographic history of recent post-glacial decline and fragmentation of populations. Each species functions as a single metapopulation more or less structured at the regional scale, with a North- South gradient of decreasing genetic diversity that fits the local dynamics of the ice cover overtime. However, we found no correlation between changes in the quantity or quality of suitable areas and effective population size over time, suggesting that species ranges moved beyond the Jura massif during the less favorable climatic periods, and that other factors than climate are at play in the dramatic decline currently observed in the three species.