Social groups are extraordinarily diverse in form and function across the animal kingdom. Whereas we understand well how many social systems are maintained, what predispose certain lineages to evolve sociality in the first place remains poorly resolved. The Australian lizard group, Egernia are a particularly useful (albeit odd) model organism in this context because they display huge diversity in social organisation between species, from species that are largely solitary, to those in which males and females form long-term pair bonds, to those in which offspring delay dispersal resulting in prolonged associations with their parents. In some instances this can result in large communal family groups consisting of up to 30 individuals. Importantly, social organisation is also highly variable within species. This provides us with a fantastic opportunity to ask what factors influence variation in social organisation within a species and how this may explain diversification in social organisation across species.

To take advantage of this opportunity we use a combination of experimental, molecular, theoretical and comparative techniques. Specifically, we have long-term field populations of several species of Egernia spanning the social continuum which allows us to characterise what constitutes social living in these lizards. We can integrate this field work with detailed experimental approaches that allows us to decipher causal relationships between variation in environmental factors and variation in key social traits which are thought to underpin transitions to more complex forms of sociality. We then combine this with similar work on species across the group, allowing us to reconstruct the steps towards social complexity, unravelling how social systems originate and are maintained. When combined, this approach should provide us with a more holistic understanding of when, where and why complex social behaviour evolves.

This work is funded by the Australian Research Council and is carried out in collaboration with Tobias Uller (Lund), Dave Chapple (Monash), Mike Gardner (Flinders), Martin Whiting (Macquarie), Charlie Cornwallis (Lund) and Dan Noble (UNSW).

If you want to know more:

Halliwell, B., Uller, T., Holland, B. and While, G. M. (2017) Live bearing promotes the evolution of sociality in reptiles. Nature Communications. 8:2030.

Whiting, M.J. and While, G. M. (2017) Sociality in Lizards. In D. Rubenstein and P. Abbot (eds) Comparative Social Evolution. Cambridge University Press, Cambridge, UK, pp – 390-426.

While, G. M., Chapple, D. G., Gardner, M.G., Uller, T. and Whiting, M. J. (2015) Egernia lizards. Current Biology, 25, 593 – 595.

While, G.M., Uller, T., Bordogna, G. and Wapstra, E. (2014) Promiscuity resolves constraints on social mate choice imposed by population viscosity. Molecular Ecology, 23: 721–732.

While, G., Uller, T. and Wapstra, E. (2009) Family conflict and the evolution of sociality in reptiles. Behavioral Ecology, 20: 245-250