Khouri, Z. | bioRxiv Science

bioRxiv2022

Evolution and systematics of the Aculeata and kin (Hymenoptera),with emphasis on the ants (Formicoidea: {dagger}@@@idae fam. nov., Formicidae).

Fossils provide unique opportunity to understand the tempo and mode of evolution and are essential for modeling the history of lineage diversification. Here, we interrogate the Mesozoic fossil record of the Aculeata, with emphasis on the ants (Formicidae), and conduct an extended series of ancestral state estimation exercises on distributions of tip-dated combined-evidence phylogenies. We developed and illustrated from ground-up a series of 576 morphological characters which we scored for 144 extant and 431 fossil taxa, including all families of Aculeata, Trigonaloidea, Evanioidea, and {dagger}Ephialtitoidea. We used average posterior probability support to guide composition of a target matrix of 303 taxa, for which we integrated strongly filtered ultraconserved element (UCE) data for 115 living species. We also implemented reversible jump MCMC (rjMCMC) and hidden state methods to model complex behavioral characters to test hypotheses about the pathway to obligate eusociality. In addition to revising the higher classification of all sampled groups to family or subfamily level using estimated character polarities to diagnose nodes across the phylogeny, we find that the mid-Cretaceous genera {dagger}Camelomecia and {dagger}Camelosphecia form a clade which is robustly supported as sister to all living and fossil Formicidae. For this reason, we name this extinct clade as {dagger}@@@idae fam. nov. and provide a definition for the expanded Formicoidea. Based on our results, we recognize three major phases in the early evolution of the ants: (1) origin of Formicoidea as ground-adapted huntresses during the Late Jurassic in the "stinging aggressor" guild (Aculeata) among various lineages of "sneaking parasitoids" (non-aculeate Vespina); (2) the first formicoid radiation during the Early Cretaceous, by the end of which all major extant linages originated; and (3) turnover of the Formicoidea at the end-Cretaceous leading to the second formicoid radiation. We conclude with a concentrated series of considerations for future directions of study with this dataset and beyond.

evolutionary biology↗

bioRxiv2022

The evolutionary history of mammoth wasps (Hymenoptera: Scoliidae)

Scoliid wasps comprise a clade of aculeate insects whose larvae are parasitoids of scarabaeid beetle grubs. While scoliids have been studied and used as biological control agents, research into the groups evolution, as well as the stability of scoliid taxonomy, has been limited by a lack of reliable phylogenies. We use ultraconserved element (UCE) data under concatenation and the multispecies coalescent to infer a phylogeny of the Scoliidae. In order to mitigate potential issues arising from model misspecification, we perform data filtering experiments using posterior predictive checks and matched-pairs tests of symmetry. Our analyses confirm the position of Proscolia as sister to all other extant scoliids. We also find strong support for a sister group relationship between the campsomerine genus Colpa and the Scoliini, rendering the Campsomerini non-monophyletic. Campsomerini excluding Colpa (hereafter Campsomerini sensu stricto) is inferred to be monophyletic, with the Australasian genus Trisciloa recovered as sister to the remaining members of the group. Out of nine genera in which more than one species was sampled, Campsomeriella, Dielis, Megascolia, and Scolia are inferred to be non-monophyletic. Analyses incorporating fossil data indicate an Early Cretaceous origin of the crown Scoliidae, with the split between Scoliini + Colpa and Campsomerini s.s. most probably occurring in the Late Cretaceous. Posterior means of Scoliini + Colpa and Campsomerini s.s. crown ages are estimated to be in the Paleogene, though age 95% HPD intervals extend slightly back past the K-Pg boundary, and analyses including fossils of less certain placement result in more posterior mass on older ages. Our estimates of the stem ages of Nearctic scoliid clades are consistent with dispersal across Beringia during the Oligocene or later Eocene. Our study provides a foundation for future research into scoliid wasp evolution and biogeography by being the first to leverage genome-scale data and model-based methods. However, the precision of our dating analyses is constrained by the paucity of well-preserved fossils reliably attributable to the scoliid crown group. Despite concluding that the higher-level taxonomy of the Scoliidae is in dire need of revision, we recommend that taxonomic changes be predicated on datasets that extend the geographic and taxonomic sampling of the current study.

evolutionary biology↗