Behavioural responses to warming differentially impact survival in introduced and native dung beetles.

Anthropogenic changes are often studied in isolation but may interact to affect biodiversity. For example, climate change could exacerbate the impacts of biological invasions if climate change differentially affects invasive and native species. Behavioural plasticity may mitigate some of the impacts of climate change, but species vary in their degree of behavioural plasticity. In particular, invasive species may have greater behavioural plasticity than native species since plasticity helps invasive species establish and spread in new environments. This plasticity could make invasives better able to cope with climate change. Here our goal was to examine whether reproductive behaviours and behavioural plasticity vary between an introduced and a native Onthophagus dung beetle species in response to warming temperatures and how differences in behaviour influence offspring survival. Using a repeated measures design, we exposed small colonies of introduced O. taurus and native O. hecate to three temperature treatments, including a control, low warming and high warming treatment, and then measured reproductive behaviours, including the number, size and burial depth of brood balls. We reared offspring in their brood balls in developmental temperatures that matched those of the brood ball burial depth to quantify survival. We found that the introduced O. taurus produced more brood balls and larger brood balls, and buried brood balls deeper than the native O. hecate in all treatments. However, the two species did not vary in the degree of behavioural plasticity in response to warming. Differences in reproductive behaviours did affect survival such that warming temperatures had a greater effect on survival of offspring of native O. hecate compared to introduced O. taurus. Overall, our results suggest that differences in behaviour between native and introduced species are one mechanism through which climate change may exacerbate negative impacts of biological invasions.