8: The chronicles of Nylanderia: Globetrotter phylogenomics and integrative species delimitation

The near-globally distributed ant genus Nylanderia (Emery) is among the world’s most diverse, with 123 described species and hundreds estimated to be undescribed. Fifteen globetrotting or invasive species are commonly encountered outside their native ranges due to their abundance and widespread distributions. A molecular approach to understanding the evolutionary history and revising Nylanderia taxonomy is needed because historical efforts have proven insufficient to define major lineages and determine species boundaries. Nomenclatural problems persist, especially where widespread globetrotting species are concerned. The disorder and frequent misidentification that has long characterized species-level taxonomy in Nylanderia is a result of the ants’ limited morphological variation combined with taxonomists’ near-complete dependence on external morphology for species delimitation. To address these problems, we generated the first genus-wide genomic dataset of Nylanderia using ultraconserved elements (UCEs) to resolve the phylogeny of major lineages, determine the age and biogeographic origin of the genus, and describe global biogeographic patterns. Sampling from seven biogeographic regions revealed an Indomalayan origin of Nylanderia and four major biogeographic clades. The Nearctic and Neotropical clades are distantly related, indicating two separate dispersals to the Americas. We also evaluated the integrity of species boundaries in four of the most widespread globetrotting Nylanderia species by sampling across their ranges and clarified their placement within biogeographic clades. In exhaustively sampling Nylanderia diversity in theWest Indies, a “hot spot” for invasive taxa, we found five adventive species among 22 in the region; many of these taxa remain morphologically indistinguishable from one another, despite being distantly related.