Thermal parental effects on offspring behaviour and their fitness consequences

Environmental and developmental conditions can drive substantial variation in offspring behaviour and developmental trajectory. While incubation temperature is well known to influence development in oviparous animals, little is known of the role of parental temperature on offspring phenotype (i.e. thermal parental effects). Following exposure of male and gravid female jacky dragons, Amphibolurus muricatus, to one of two thermal treatments (short-bask versus long-bask) and incubation of their eggs at a constant temperature, we examined whether the preovipositional parental treatment influenced offspring performance-related behaviours. We detected main and interactive effects of parental treatment on offspring behaviours including feeding, exploration and antipredator. Sex-specific effects of parental treatment included long-bask sons being more likely to feed and being bolder following predatory attack than short-bask sons, while the differences between treatments for daughters were smaller. Behaviours were not consistent between 1 week and 1 month of age and showed little correlation across behavioural contexts. Some behaviours emerged as promising mechanisms of documented parental effects on offspring growth and survival in these individuals. In particular, boldness among long-bask sons in an antipredator context may be linked to their greater rates of growth posthatching. Overall, our findings suggest that thermal parental effects influence variation in animal behaviours relevant for subsequent fitness outcomes.