Maternal presence facilitates plasticity in offspring behavior: insights into the evolution of parental care

Fundamental to the definition of parental care is that care confers benefits to the offspring. However, the mechanisms resulting in these benefits remain poorly understood, particularly in species where postnatal care is not obligatory. Here, we address this shortcoming using a lizard, Liopholis whitii, in which family life is facultative and relatively simple – extending to prolonged associations between parents and offspring within the parental territory. Using a split-clutch design, we housed offspring either with their mother or alone during the first eight weeks of postnatal life and examined whether maternal presence affected (i) the expression of key functional behaviors, and (ii) learning ability in a biologically relevant anti-predatory task. We found that offspring housed with their mothers expressed heightened levels of activity, boldness and exploration compared to offspring who were housed alone. Furthermore, we show that associating with mothers during early postnatal periods led to improved offspring performance in the anti-predation learning task. Together these results suggest that even relatively simple forms of enhanced parent-offspring association can have significant impacts on offspring traits. We argue that such effects may help refine and stabilize parent-offspring associations early in their evolution, potentially setting the stage for the elaboration of both parent and offspring behaviors.