Creatures of habit: similar but more repeatable behaviours in insular compared with mainland lizards
(2026) Animal Behaviour — Vol. 233, p. 123493 (2026)
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Gavriilidi, Ioanna 
Pafilis, Panayiotis Van Damme, Raoul
- Abstract
- Available online xxx MS. number: 25-00274R Keywords: aggression behaviour cognition evolution islands lizard personality Podarcis erhardii Island habitats often differ markedly from those on the mainland in many biotic and abiotic factors. Typically, they harbour fewer predator, competitor and prey species and resources tend to be scarcer or more variable. In response, many island dwelling species have evolved a series of morphological, physiological and life-history adaptations, collectively referred to as 'island syndrome'. Although morphological and life-history island-induced trait shifts are particularly well documented, the effects of insularity on behaviour have attracted much less attention. In this study, we examined the effects of insularity on two putatively interrelated behavioural domains: cognition and personality. We compared cognitive and personality-related traits of Aegean wall lizards, Podarcis erhardii, from several mainland, island and small islet populations. We anticipated that the ecological peculiarities of insular environments would induce convergent changes in the behaviour of island lizards. However, we found few clear or consistent shifts in cognitive or personality trait means that were linked to insularity. One notable exception was the discernible decrease in the aggressiveness of insular lizards compared with their mainland counterparts, suggesting that high population densities on islands alter the economics of territorial defence. However, we observed recurrent differences in behavioural variation: insular lizards exhibited higher repeatability (higher among-and lower within-individual variation) in their behav-ioural traits (predominantly aggressiveness, risk-taking and sociability). This suggests increased behavioural specialization and reduced flexibility in insular populations compared with mainland populations. Our findings highlight the complexity of behavioural evolution in insular systems and suggest that, unlike morphological and life-history traits, behavioural responses to insularity may be more variable and nuanced than previously assumed.
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Gavriilidi, I., Baeckens, S., Pafilis, P., & Van Damme, R. (2026). Creatures of habit: similar but more repeatable behaviours in insular compared with mainland lizards. Animal Behaviour, 233, 123493. https://doi.org/10.1016/j.anbehav.2026.123493 (Original work published 2026)