Range shifts as drivers of niche breadth and dispersal ability in wild populations

Range expansion can have profound ecological and evolutionary consequences that feedback on the expansion process itself. With global climate change causing widespread species range shifts to higher latitudes and altitudes, it is essential that we better understand these dynamics during native range expansion in the wild. In a recent study on poleward-spreading treefrogs (Hyla cinerea), Edwards et al. (2024) measured how morphological and physiological traits differed between populations from the recently expanded and historic range. They found that range-edge frogs had increased cold tolerance and longer legs associated with better dispersal, which could strongly affect the rate and geographic limits of expansion. Edwards et al. then show how species distribution models fit separately to the historic and expanded range more accurately predict habitat suitability near the historic range boundary. This paper provides a timely and compelling example of rapid differentiation in dispersal and niche traits during native range expansion, and explores ways in which we can model species range shifts while accounting for this phenotypic variation in space and time.