Species constrained to mountains are considered to be highly susceptible to climate change. Their restriction to high altitudes has often caused disjunct distributions and intraspecific differentiations. Up to now, patterns of disjunct distributions have rarely been taken into account for climate envelope modeling. The aim of this study was to investigate whether a region-specific modeling approach leads to more realistic predictions of future ranges under climate change.
We applied a climate envelope model on an intraspecific scale to analyze the cold-adapted ground beetle Carabus sylvestris (Coleoptera: Carabidae), showing a disjunct distribution in Central and Eastern European mountain systems. We split the species’ range into three geographic groups and modeled (1) low mountain range populations in Central Europe, populations in (2) the Alps and (3) the Carpathians individually to investigate intraspecific climate niche characteristics and their implications assuming two emission scenarios for 2050 and 2080. We compared these models with one for (4) the entire species’ range.
Our findings indicate an intraspecific climate niche variability and serious range contractions for the considered regions. The potential distribution of (1) low mountain range populations will shift almost entirely to higher altitudes of inaccessible high mountains. Suitable habitats for populations in (2) the Alps will disappear by 2080 under scenario A2a. (3) Carpathian populations will lose all favorable areas by 2050, independent of the applied scenario. However, model results for (4) the entire range do not illustrate region-specific implications of altering conditions and thus underestimate the impact of a changing climate.
Hence, the whole species is prone to climate change, which would not have been revealed without the applied scale of modeling. We conclude that an intraspecific modeling scale might foster more realistic predictions for disjunctively distributed species.