Phylogenomics resolve the systematics and biogeography of the ant tribe Myrmicini and tribal relationships within the hyperdiverse ant subfamily Myrmicinae

Ants are a globally distributed and highly diverse group of eusocial
animals, playing key ecological roles in most of the world’s terrestrial
ecosystems. Our understanding of the processes involved in the evolution
this diverse family is contingent upon our knowledge of the phylogeny of
the ants. While relationships among most subfamilies have come into
resolution recently, several of the tribal relationships within the
hyperdiverse subfamily Myrmicinae persistently conflict between or within
studies, mirroring the controversial relationships of the Leptanillinae
and Martialinae to the remaining ant subfamilies. Another persistent issue
of debate in ant phylogenetics is the timing of major evolutionary events
as inferred via divergence dating. Here, we test the topology of the
myrmicine tribes using genome scale data, inspect gene tree-species tree
concordance, and use posterior predictive checks and tests of
compositional heterogeneity to infer sequence characteristics which
potentially introduce systematic bias in myrmicine tribal topology.
Furthermore, we test the placement of the fossil †Manica andrannae by
integrating phylogenomic and morphological data from nearly all species
within the genus Manica, and a broad sampling of its sister genus Myrmica.
Subsequently, we demonstrate the effect of fossil placement on overall
divergence times in the Myrmicinae. We then re-evaluate the historical
biogeography of the Myrmicini and Pogonomyrmecini considering newly
generated genetic data and insights from our phylogenomic results. We find
that our current understanding of tribal topology in the Myrmicinae is
strongly supported, but this topology is highly sensitive to compositional
heterogeneity and gene-tree species-tree conflict. Our fossil placement
analyses strongly suggest that †Manica andrannae is a stem Manica species,
and that placement of this fossil in the crown group affects not only
divergence dates within the tribe Myrmicini, but also has broad
implications for divergence times throughout the formicoid clade. The
results of our biogeographic reconstructions indicate a South American
origin for the Pogonomyrmecini + Myrmicini, with the MRCA of Myrmica
inhabiting the western Nearctic in the early Miocene prior to repeated
dispersal across Beringia throughout the Miocene and Pliocene. The MRCA of
Manica, on the other hand, was inferred to have a Holarctic range prior to
vicariance during the Pliocene. Unexpectedly, we found strong support in
the Pogonomyrmecini for three coordinated dispersal events from South to
Central America during the early Miocene, which has been previously
proposed as an early biotic interchange event prior to the more commonly
accepted 3.5 Ma closure of the Isthmus of Panama.