Deconstructing collective building in social insects: implications for ecological adaptation and evolution

Nests built by eusocial insect species are often complex structures consisting of multiple effectively integrated and functionally distinct substructures. Stigmergy, self-assembly and self-organisation have been proposed as the mechanisms that translate simple individual behaviour into coordinated collective activity. Here, we consider these processes focusing on their implications for the generation of new structures, nest adaptiveness and the evolution of building rules. We discuss in particular how self-organisation and stigmergy may guide the shift between substructures during building and generate new elements, either as an indirect result of building rule sets evolved for other purposes and under direct selection. The same mechanisms generate local, short-term adaptation through exploration of the phenotype space of the construction. Finally, we introduce the hypothesis that feedback dynamics create evolutionary transition between collective level phenotypes when mutations arise in the worker line, thus facilitating colony survival and affecting the evolution of collective building rules and of nest shape. This smooth transition is possible only when the new and the old rule variant are compatible. We call for new research that investigates self-organisation in collective building from an evolutionary perspective.