Range shifts in response to past and future climate change: Can climate velocities and species' dispersal capabilities explain variation in mammalian range shifts?

Aim: Range shift is a relatively well-understood response to climate change, but our ability to predict shifts is limited. Two factors that may cause variation in range shifts across species are dispersal ability and varying rates of climate change through time and across space. Here, we assess patterns of range shifts during the late Quaternary and estimate how the velocity of climate change and the dispersal ability of a species affect the magnitude of species range shifts in response to climate change. Location: North America. Methods: We hindcast species distribution models for 122 North American mammals to five times over the past 17,000 years and forecast them to two future times given two emissions scenarios. Generalized additive models were constructed to quantify the importance of dispersal ability and the velocity of temperature and precipitation in determining the magnitude of range shift expected for individual species. Results: Hindcasted and forecasted ranges demonstrate the variety of responses to climate change. In general, species shifted their ranges in a northerly direction (NW, N, NE) regardless of the type of climate change (i.e., warming vs. cooling). The highest rates of range shifts during the past occurred during periods of relatively rapid climate change (Last Glacial Maximum/Bolling-Allerod and Bolling-Allerod/Younger Dryas transitions). Rates of range shifts for the future are projected to be significantly higher than any of the past intervals. The velocity of climate change is significantly associated with the magnitude of range shifts during climate transitions that occur over longer time-scales, while maximum dispersal distance is important during periods of rapid climate change. Main Conclusions: Our results suggest that both the dispersal ability and the velocity of climate change are significantly associated with species' range shifts. However, the importance of these two factors is context-dependent and depends on the interaction of the rate of climate change and the length of time over which the change occurs.