Admixture between lineages of the tramp ant Technomyrmex albipes revealed by mitochondrial and ultra-conserved element sequencing

Hybridisation between divergent populations can lead to various outcomes, including potentially increased invasiveness. In this study, we investigated the genetic background of a recent outbreak of a tramp ant species in southern Taiwan. Combining morphological data and a global Technomyrmex phylogeny, based on 1,796 newly-generated and publicly-available cytochrome c oxidase I (COI) barcodes, we identified the species responsible for the outbreak as Technomyrmex albipes . Further haplotype network analysis, based on 399 T. albipes samples, revealed two major geographic groups corresponding to the Indian Ocean Region and Southeast Asia. Population structure inferred from ultra-conserved element sequence data revealed that two genetically similar lineages are geographically separated by a third lineage in western Taiwan, indicating a potential human-mediated dispersal event. We found that one of the contact zones between these lineages coincides with the region where outbreaks were reported. Several individuals in this area exhibited admixed genotypes and this potential hybridisation was further supported by simulations. Based on these findings, we proposed that the outbreaks are potentially attributable to recent admixture between lineages in southern Taiwan.