Are behavioural syndromes sex specific? Personality in a widespread lizard species

Understanding how and why consistent behavioural traits (i.e. animal personality) vary between individuals, and identifying the mechanisms that underlie such variation, is a key focus in behavioural and evolutionary ecology. In many animals, male and female behaviour often diverges in response to different selection pressures and life history trajectories post-maturation. Despite this, animal personality studies spanning several personality traits rarely consider both sexes, ignoring the very strong possibility that key components of personality, behavioural consistency and behavioural correlations, may vary between males and females. Furthermore, such variation can play an important role in ecological processes such as mediating the invasion propensity of a species. Here, we took an animal personality approach to studying the behaviour of a repeatedly successful invasive species, the delicate skink (Lampropholis delicata). We investigated whether male and female delicate skinks differed in their personality across five behavioural traits, as sex differences in behaviour could provide a mechanism that explains the delicate skink’s successful invasion history via accidental introductions. We found that females were more social than males and showed a trend towards being faster explorers. Both sexes shared the same behavioural syndrome suggesting that it is evolutionarily stable and not easily decoupled by selection. Specifically, skinks that were consistently more active explored environments faster and were more likely to bask with other skinks. In sum, we found limited evidence of sex-specific personality in the delicate skink suggesting that both sexes might have an equal invasion potential. More broadly, our study highlights the need to consider whether, in fact, differences in personality are important in mediating a species propensity to invade. Significance statement: Males and females likely differ in their personality because they often face different selection pressures when they are adults. An individual’s personality may also determine how likely they are to invade novel environments. Thus, we compared personality traits of males and females in an invasive species, the delicate skink, for what it may reveal about the potential mechanisms that drive the species successful invasion history. We found that females were more social and showed a trend towards being faster explorers than males. Both sexes had positive correlations between activity, exploratory and social behaviour suggesting the presence of a non-sex-specific behavioural syndrome. Our results suggest limited behavioural variation between the sexes and that both sexes may have an equal invasion potential.