The aculeate ancestry and evolution of the ants (Hymenoptera, Aculeata, Formicidae)
Abstract
Ants are abundant, ecologically influential, and diverse eusocial Hymenoptera. The dominant narrative for
their origin and radiation is that of E. O. Wilson and Bert Hölldobler, known as the “dynastic succession
hypothesis”. Wilson and Hölldobler contend that the crown (= extant) ants originated during the peak of the
angiosperm radiation, ~110–100 million years ago, and that post-K/Pg biodiversity recovery occurred in a
sequence dictated by degree of social derivation. To address this hypothesis, we reconsidered the
phylogenetic scope of the problem, and generated a large morphological dataset (576 characters for 575
taxa) which included extant species with ultra-conserved element (UCE) sequences and hundreds of
fossils. These fossils represent a comprehensive sample of Mesozoic Aculeata, Trigonaloidea,
Evaniomorpha (= Evanioidea), plus the enigmatic Jurassic taxa †Bethylonymoidea and †Ephialtitoidea. To
test the geochronological prediction of the dynastic succession hypothesis, we combined the nucleotide
and morphological data in a series of tip-dating analyses. To test the “scale of sociality” hypothesis, we
conducted an MCMC estimation of ancestral states for all morphological characters on a distribution of
trees from our best-supported analysis, with emphasis on those traits with social-behavioral correlates.
Based on the results from our two-pronged test of the Wilson- Hölldobler hypothesis, we provide a
reinterpretation of the origin and evolution of the ants, from the ancestor of the Aculeata to that of the crown
Formicidae.