Higher heat acclimation ability in a non-native versus a native dung beetle (Onthophagus spp.)

Abstract

Invasive species may be more capable of adjusting to climate warming via phenotypic plasticity than native species since plasticity is thought to increase invasion success. Physiological plasticity via acclimation is one way in which organisms can adjust their thermal tolerance in response to temperature change, but few studies have addressed whether invasive species have greater thermal plasticity compared to native congeners. Here we investigated whether thermal plasticity via temperature acclimation varies between two Onthophagus dung beetle species, the non-native Onthophagus taurus and the native Onthophagus hecate, collected from both Florida and Tennessee, USA. We expected the non-native O. taurus to demonstrate greater plasticity than the native O. hecate; we also predicted that beetles from Florida would have reduced plasticity since their environment is less thermally variable. To examine thermal plasticity, we measured shifts in time until loss of function (i.e., leg mobility) following acclimation to hot or cold temperature treatments. We found that non-native O. taurus from Florida acclimated to warm temperatures, increasing time to loss of function following warm treatments; unexpectedly, O. taurus from Tennessee showed no warm acclimation ability. Onthophagus hecate did not acclimate to warm temperatures in either location. In contrast, both species showed similar levels of cold acclimation. Taken together, our results suggest that the non-native species, O. taurus, will be more capable of using physiological adjustments to respond to climate warming than the native species, O. hecate.