Should I stay or should I go? The influence of temperature and sex on predator-induced responses in newts

• Temperature and sex represent major sources of phenotypic variation in ectotherms.
• We examined the influence of sex and temperature on defensive strategies in newts.
• Male defensive responses are more thermally sensitive than in females.
• Females flee predators at higher speeds than males.
• Temperature and sex are important determinants of the newt defensive repertoire.

Ectotherms compensate for variation in thermal environments in diverse behavioural ways. Despite widely occurring sex differences in morphology and physiology, the sex-specific thermal sensitivity of behavioural traits has received little attention. We tested the interactive influence of sex and environmental temperature on predator-induced responses in the Alpine newt, Ichthyosaura alpestris. Escape decisions and the duration of flight were less thermally sensitive in females than in males. Males ran more slowly than females. Both sexes required more stimuli at intermediate temperatures than at other temperatures. We conclude that temperature and sex are important determinants of a newt's defensive repertoire. The sex-specific thermal sensitivity of defensive responses suggests both asymmetric selection regimes and an impact of environmental change in newt populations.