Identifying the costs benefits and incidences of parental care in a social lizard

In this study, we used a social skink species, Liopholis whitiii, to quantify the costs and benefits of parental care and to test how the expression of care varies with key ecological conditions. To achieve this we carried out a detailed enclosure experiment manipulating habitat structure with data collected over 7 years from a natural population. We found that the expression of parental care was extremely variable in the natural population, with 8-62 % of parents caring across years. This variation in care was strongly linked to variation in precipitation, with a greater proportion of the population caring in drier years compared to wetter years. There was also variation in the expression of care across treatments in the enclosure experiment, with the incidence of care significantly higher when high quality habitats were clumped together. Across both the experiment and the natural population, offspring that were cared for had increased growth but not survival. We found no costs of care to parents in either the experiment or the natural population. Combined, these results suggest that poor ecological conditions result in an increase in the expression of parental care. This suggests that parental care is most common under conditions when we would expect it to be most costly for parents. However, as our results suggest that care has little costs to parents, patterns of parental care in this system may be driven by offspring rather than parents.