Data from: The evolution of abdominal microbiomes in fungus-growing ants

The attine ants are a monophyletic lineage that switched to fungus-farming
ca. 55-60 MYA. They have become a model for the study of complex symbioses
after additional fungal and bacterial symbionts were discovered, but their
abdominal endosymbiotic bacteria remain largely unknown. Here we present a
comparative microbiome analysis of endosymbiotic bacteria spanning the
entire phylogenetic tree. We show that, across 17 representative sympatric
species from eight genera sampled in Panama, abdominal microbiomes are
dominated by Mollicutes, α- and γ-Proteobacteria, and Actinobacteria.
Bacterial abundances increase from basal to crown branches in the
phylogeny reflecting a shift towards putative specialized and abundant
abdominal microbiota after the ants domesticated gongylidia-bearing
cultivars, but before the origin of industrial-scale farming based on
leaf-cutting herbivory. This transition coincided with the ancestral
single colonization event of Central/North America ca. 20 MYA, documented
in a recent phylogenomic study showing that the entire crown-group of the
higher attine ants, including the leaf-cutting ants, evolved there and not
in South America. Several bacterial species are located in gut tissues or
abdominal organs of the evolutionarily derived, but not the basal attine
ants. The composition of abdominal microbiomes appears to be affected by
the presence/absence of defensive antibiotic-producing actinobacterial
biofilms on the worker ants’ cuticle, but the significance of this
association remains unclear. The patterns of diversity, abundance, and
sensitivity of the abdominal microbiomes that we obtained explore novel
territory in the comparative analysis of attine fungus-farming symbioses
and raise new questions for further in-depth research.