Towards an eco-evo-devo theory for the evolution of eusociality: Integrating theory, field experiments and molecular genetics

One of evolutionary biology’s key challenges is to understand the major evolutionary transition from solitary breeding to eusocial societies with reproductive division of labour between morphologically and behaviourally distinct castes. In this project, we take up this challenge by an integrated theoretical and experimental approach. In the first part of this project, we will develop a new theoretical framework, unifying the quantitative eco-evolutionary models of kin selection theory with the mechanistic but more conceptual theoretical approach of evolutionary developmental biology. In addition to new general predictions, we aim to provide testable quantitative models which can be applied directly to suitable species that occupy the “twilight zone” between solitary living and primitive eusociality. In the second part of the project, we will conduct experimental field studies on such a species, the relatively well-studied facultatively eusocial allodapine bee, Exoneura robusta, in which solitary and social breeding are known to coexist in the same populations. By exposing bees to different ecological conditions (food availability, nest density and predation risk) we aim to discover proximate environmental triggers for eusocial behaviour and to assess the fitness consequences of different social strategies. The underlying genetic correlates of social behaviours will be explored with transcriptomics and comparative phylogenetic analyses with other (facultatively) eusocial species. Last but not least, by combining field data, molecular analyses and species-specific evolutionary models, we will quantitatively test the new theoretical predictions (1) on E. robusta, to predict the outcome of the experiments, and (2) on Halictus rubicundus, another relatively well-studied facultatively eusocial (halictine) bee species, to predict how global warming will cause its eusociality to spread north along a latitudinal cline. If successful, this highly collaborative project could provide a major step forward towards understanding the evolution of eusociality.