Does sociality affect cognitive ability in lizards?: Learning and behavioural flexibility in Australian skinks

Comparative cognition recently advanced towards a wider taxonomic approach evidenced by an increase in non-avian reptile learning studies but our knowledge still exhibits many gaps. In primates, sociality is linked to enhanced cognitive ability. My aim was to investigate if sociality affects cognitive ability in four Australian lizard species. I specifically focused on behavioural flexibility, which is an index of an organism's ability to cope with environmental change at a cognitive level. I applied the ID/ED attentional set-shifting paradigm which includes several colour / shape discriminations, reversals of these discriminations, an acquisition of a new colour / shape discrimination and a shift from colour to shape (and vice versa). Moreover, I tested how age affects learning, if behavioural flexibility correlates with unpredictable environmental conditions and how inhibitory control is exercised in different contexts. Finally, I tested if individual differences in learning could be explained by sex utilising a meta-analytic approach. All four tested species discriminated between one dimensional stimuli, however, only three out of four showed behavioural flexibility and only two species successfully completed the shift stage learning each set of stages like a new problem. Furthermore, juvenile lizards learnt at adult levels, behavioural flexibility was enhanced in the arid-adapted species and lizards showed context specific inhibitory skills. Neither trials to criterion nor the number of successful individuals differed between the tested species belonging to the Egernia group implicating no adaptations based on sociality in the tested context. Furthermore, the fourth tested, non-Egernia species, failed to perform even a single reversal. Importantly, resource predictability predicted learning proficiency in one species suggesting that other species-specific adaptations underlie differences in learning between species. Similarly, in my meta-analysis a sex difference emerged only between species. Overall, my results contribute important new insights into lizard cognition, however, we need more data on a broader range of lizards to make distinct conclusions on how sociality or ecology affect learning.