The evolution of altruistic workers in termites and their molecular underpinnings

• Applicant: Professorin Dr. Judith Korb
• Subject Area: Evolution, Anthropology ; Sensory and Behavioural Biology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 501764160

Eusocial insects, like honeybees and ants, are textbook examples of social evolution. They are characterized by reproductive division of labour with a one or a few reproducing individuals, while the other colony members perform all other tasks such as brood care and defence. This resembles division of labour in multicellular organisms with cells specialized in reproduction (germline) and somatic tissues performing all other tasks. Accordingly, social insects have been called ‘superorganisms’ and the evolution of eusociality has be classified as a major evolutionary transition.Termites, the second major lineage of social insects, are less studied. They are all eusocial insects because of the presence of queens and kings and sterile soldiers. Yet, the degree of worker altruism varies profoundly between lineages. It ranges from (i) totipotent ‘false workers’ which develop in reproductives and (ii) non-sterile ‘true workers’ with reduced reproductive options, to (iii) sterile ‘true workers’. Only the third type qualifies as having passed a major evolutionary transition. The occurrence of these worker types aligns with the social complexity and ecology of the species. Yet the evolutionary history of worker altruism is unclear. Phylogenetic reconstructions provide an ambiguous signal of two alternative, equally parsimonious hypotheses. Also other traits, like development, do not yield clear answers. Thus, there is a nearly 40 years’ debate on the evolutionary history of termite sociality centring on these hypotheses.We aim to uncover the molecular underpinnings of worker development using genomic and transcriptomic approaches. By studying crucial species of different degrees of worker altruism across the termites’ phylogeny, we will identify homologous gene regulatory networks. They will allow us to deduce the evolutionary history of worker altruism, test the two alternative hypotheses, and thus solve a long-standing controversy. Our study also offers a rare opportunity to track the history of a major evolutionary transition. Finally, it will allow future studies to map ecological traits to transitions and infer potential driving forces of social evolution.

• DFG Programme: Research Grants