Ultraconserved element (UCE) phylogenomics illuminates the evolutionary history and biogeography of Dorymyrmex pyramid ants

Latitudinal diversity gradients are one of the most widely discussed patterns in global biogeography, generally in the context of high diversity in tropical regions. In contrast, ‘amphitropical’ or ‘inverse’ distributions, once thought to be unusual, are increasingly recognized as common among many hymenopteran insects. One such group is the ant genus Dorymyrmex, which specializes in arid habitats throughout the Americas. To evaluate when and how Dorymyrmex acquired its present-day distribution, I sequenced partial genomes of 167 Dorymyrmex representing 69 species by targeting ultraconserved elements (UCEs). A matrix of 870 genetic loci was used to infer maximum likelihood and Bayesian phylogenies, estimate divergence dates and reconstruct hypothesized ancestral areas. These new analyses reveal that Dorymyrmex comprises four species groups, the D. flavescens, tener, wolffhuegeli, and pyramicus groups. The D. pyramicus group likely dispersed from South America to North America only once, via Central America. Like many Hymenoptera, this dispersal occurred before the traditional closure date of the Isthmus of Panama, corroborating and extending the results of previous studies. Finally, I discuss life history strategies of Dorymyrmex that may have contributed to the geographic and genetic radiation of the D. pyramicus group, detail significant insights into Dorymyrmex morphology and classical taxonomy with new comparative illustrations, and provide recommendations for future work.