Résumé
Eusociality, Darwin’s special difficulty, has been widely investigated but
remains a topic of great debate in organismal biology. Eusocial species
challenge existing theories, and the impact of highly integrated societies
on diversification dynamics is controversial with opposing assertions and
hypotheses in the literature. Here, using phylogenetic approaches in
termites – the first group that has evolved eusociality – we assessed the
fundamental prediction that eusocial lineages have higher diversification
rates than non-eusocial clades. We found multiple lines of evidence that
eusociality provided higher diversification as compared to
non-eusociality. This is particularly exacerbated for eusocial species
with ‘true’ workers as compared to species with ‘false’ workers. Because
most species with ‘true’ workers have an entirely prokaryotic microbiota,
the latter feature is also related to higher diversification rates, but it
should be investigated further, notably in relation to angiosperm
diversification. Overall, this study suggests that societies with ‘true’
workers are not only more successful at ecological timescales but also
over millions of years, which further implies that both organism- and
species-level traits act on species selection.