Our scientists from SP2 published an excellent publication in the Proceedings of the Royal Society B – Biological Sciences (IF 5,35; Nature index journal) focusing on the evolution of an immune system in eusocial termites. The immunity is usually well studied at the cell and individual level of model organisms like mice, fruit flies or humans. Also, some efforts to widen understanding of the immune defence of social organisms have been made, such as in bees, thrips and wasps. However, our study of the co-evolution mechanism of the immune system and eusociality in termites is unique as no similar study on termites has been presented so far.
We recognized a significant reduction of immune genes expressed as the level of sociality is growing. This pattern is probably caused by specific social behaviour reducing a load of pathogens in the colony and maintaining particular microbial communities in the nest. Moreover, we also noticed a different immune gene expression between the castes in a single colony, probably due to individuals' varying tasks in different environments.
The evolution of biological complexity is associated with the emergence of bespoke immune systems that maintain and protect organism integrity. Unlike the well-studied immune systems of cells and individuals, little is known about the origins of immunity during the transition to eusociality, a major evolutionary transition comparable to the evolution of multicellular organisms from single-celled ancestors. We aimed to tackle this by characterizing the immune gene repertoire of 18 cockroach and termite species, spanning the spectrum of solitary, subsocial and eusocial lifestyles. We find that key transitions in termite sociality are correlated with immune gene family contractions. In cross-species comparisons of immune gene expression, we find evidence for a caste-specific social defence system in termites, which appears to operate at the expense of individual immune protection. Our study indicates that a major transition in organismal complexity may have entailed a fundamental reshaping of the immune system optimized for group over individual defence.
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