Range Expansion and Dispersal Traits of Green Treefrogs (Hyla cinerea)

Abstract

Abstract. Since the 1980s, there has been rapid and ongoing hypothesized climate-related range expansion in native Green Treefrogs (Hyla cinerea) northward and eastward in Illinois, Kentucky, and Indiana, United States. Because anuran leg length is positively correlated with locomotor function, longer legs have been shown to facilitate dispersal of invasive anuran populations undergoing biological invasion. These recent range-expansion populations of H. cinerea provide an ideal opportunity to test if a native frog species exhibits similar changes in dispersal-related traits to those found in invasive species. We tested if individuals on the front end of this expansion exhibit significant differences in femur length when compared with frogs collected from the historical-range distribution. We predicted that frogs found at the expansion edge would have longer femur lengths than their counterparts located in historical parts of the range. We found that relative to snout–vent length (SVL), the femur lengths (FL) of H. cinerea from expanded ranges were on average significantly larger than those of frogs from the historical range. This suggests that native expanded-range populations of this species have undergone changes in FL. Rapid shifts in morphological traits of a native species, H. cinerea, in expanded-range populations, appear to mimic morphological trade-offs observed for invasive species of anurans.