The complex effect of illumination, temperature, and thermal acclimation on habitat choice and foraging behavior of a pit-building wormlion

摘要

Habitat selection has consequences for an animal's fitness, especially for sit-and-wait predators with limited mobility, and which cannot always correct earlier suboptimal choices. Environmental change may nevertheless lead individuals to relocate to another site, although such relocations can be energetically costly or risky. Temperature and illumination are two important factors that undergo change in seasonal and daily cycles that may impact habitat quality. Animals must therefore either acclimate to the new conditions or relocate. Wormlions are sit-and-wait, trap-building predators whose success in foraging is highly dependent on their surroundings. Here, we manipulated temperature (high, low, and moderate) and let the wormlions choose between lit and shaded conditions. We found that the typical wormlion preference for shaded microhabitats decreased with increasing temperature. We then followed wormlion behavior under a fullfactorial design of two constant illumination conditions (light vs. shade) and three temperatures. Although both constant light and high temperature reduced foraging performance, expressed in pit construction tendency and pit area, the two conditions had a non-additive effect. Acclimation to extreme thermal conditions moderated the negative effects of such temperatures, expressed in a higher tendency to construct a pit, and equalized performance across temperatures. Finally, the high temperature reduced behavioral consistency while acclimation increased it, suggesting that consistency is impaired by unfavorable environmental change. To conclude, while an environmental change usually affects several environmental factors simultaneously, the induced behavioral change is neither synergic nor additive and can even differ from the response to each unfavorable environmental factor in isolation.