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

Background: 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.
Goal: 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.
Methods: Using a repeated measures design, we exposed small colonies of introduced O. taurus..., To investigate behavioural plasticity in these species, we used a repeated measures design to quantify reproductive behaviours of single species colonies (n=18 colonies per species) in response to changes in their thermal environment. Each colony had five beetles (two males and three females). Before the start of the trials, we weighed each beetle to control for the effects of body size on brood ball size. We placed all experimental beetle colonies in plastic 2 L rectangular containers (13.5 x 10.2 x 28.2 cm) filled to a depth of 24 cm with a 4:1 mixture of topsoil:sand. We mixed the soil with water to create a standardized moisture level across colonies, and we covered the container with aluminum mesh to prevent escape of the beetles. 
 We used 43W halogen light bulbs to heat experimental colonies because the bulbs produce a gradient of warming in the soil, mimicking soil gradients produced by the sun. The distance of the bulb to the soil surface determined the degree of warming at the...,