Consistent social structure within aggregations of the Australian lizard, Egernia stokesii across seven disconnected rocky outcrops

Abstract

The Australian skink lizard Egernia stokesii lives in aggregations of up to 17 individuals. Previously, at one site, these aggregations have been shown to comprise paired unrelated individuals and several cohorts of their young. To investigate whether social structuring in this species is a response to ecological conditions or is phylogenetically constrained, we sampled social aggregations of E. stokesii from seven geographically adjacent rocky outcrops (including the site previously studied) that differ in the availability of homesite crevices. Analysis of genotypes from ten microsatellite loci indicate that social structures were similar at all sites and were comparable with that of the previous study. Over all sites highly significant positive relationships were observed between the number of crevices at a site and both the number of lizards and the number of social groups. Social structure in this species seems to be phylogenetically constrained, at least in relation to the abundance of potential homesite crevices.