Learning from lizards : the causes and consequences of plasticity

Organisms are shaped by the environment they experience ‚Äö- often through changes in their form and function. This is particularly evident during early development where biotic and abiotic factors can result in both reversible and permanent changes in the expression of behavioural and morphological traits, often with significant fitness consequences. My thesis experimentally investigated how environmental factors impact the expression of traits, with a special focus on learning abilities, using two distinctive reptilian models. Using the family-living lizard, Liopholis whitii, that displays long-term, stable male-female pair bonds and prolonged parent-offspring association, I examined (i) how resource availability experienced during gestation impacted offspring learning ability, (ii) how the social environment, in terms of maternal presence vs absence, impacted the expression of behaviour and learning ability and the consequences of this for offspring growth, and (iii) whether mate familiarity impacted a lizard's use of different learning strategies (asocial vs social information use). My results showed that early life conditions can significantly influence the expression of key offspring traits but in highly context dependent ways. First, I found that offspring who developed under low gestational resource conditions did better in a foraging learning task, whereas offspring from high resource conditions did better in an anti-predatory task suggesting that early life stressors may evoke trade-offs between the development of different cognitive domains. Second, I found that offspring who developed with their mother learned more quickly, and were bolder, more active and exploratory compared to offspring developed alone, providing novel insights into the role of behavioural plasticity in the early evolution of parental care. Finally, I found that mate familiarity impacted an individual's propensity to utilise social learning but in more nuanced ways than theory would predict. I complemented these experiments on L. whitii with a broad examination of the links between developmental conditions, form and function using anoles lizards. Specifically, I reared anole hatchlings comprising two types of ecomorphs, Anolis sagrei and A. carolinensis, on different structural habitats to investigate the extent to which plasticity in limb morphology is related to behavioural and locomotor performance. These results suggested an important role of the developmental environment on locomotor performance, but that this was unrelated to associated changes in limb morphology. Overall, my thesis provides insight into the important of the early development for shaping organisms, even if traits are not always functionally linked, and the importance of understanding the context in which traits are expressed.