Differential effects of past climate warming on mountain and flatland species distributions: a multispecies North American mammal assessment

Abstract

ABSTRACTAim The magnitude of predicted range shifts during climate change is likely to be different for species living in mountainous environments compared with those living in flatland environments. The southern edges of ranges in mountain species may not shift northwards during warming as populations instead migrate up available elevational gradients; overall latitudinal range appears therefore to expand. In contrast, flatland species should shift range centroids northwards but not expand or contract their latitudinal range extent. These hypotheses were tested utilizing Late Pleistocene and modern occurrence data.Location North America.Methods The location and elevation of modern and Late Pleistocene species occurrences were collected from data bases for 26 species living in mountain or flatland environments. Regressions of elevation change over latitude, and southern and northern range edges were calculated for each species for modern and fossil data sets. A combination of regressions andanovas were used to test whether flatland species shift range edges and latitudinal extents more than mountain species do.Results Flatland species had significantly larger northward shifts at southern range edges than did mountain‐dwelling species from the Late Pleistocene to the present. There was also a significant negative correlation between the amount of change in the latitude of the southern edge of the range and the amount of elevational shifting from the Late Pleistocene to the present. Although significant, onlyc. 25% of the variance could be explained by this relationship. In addition, there was a weak indication that overall range expansion was less in flatland‐dwelling than in mountain‐dwelling species.Main conclusions The approach used here was to examine past species’ range responses to warming that occurred after the last ice ages as a means to better predict potential future responses to continued warming. The results confirm predictions of differential southern edge and overall range shifts for species occupying mountain and flatland regions in North America. The findings may be broadly applicable in other regions, thus allowing better modelling of future range and distribution related responses.