Phylogenomic analyses reveal the evolution of the wingless reproductive castes in Technomyrmex ants

Abstract

Technomyrmex Mayr, 1872 is a dolichoderine ant genus that includes several species widely distributed beyond their native ranges. Some species exhibit a unique reproductive system in which 2 wingless castes, specifically intercaste females and ergatoid males, serve as the primary reproductives in a colony while typical winged queens and winged males are retained for dispersal. However, the evolutionary origin of these wingless reproductive castes remains unclear. Using ultraconserved element capture, we analyzed 86 samples representing 33 species, as well as 5 outgroup genera, to study caste evolution in Technomyrmex. Phylogenies were reconstructed using both maximum-likelihood and species-coalescent approaches, with fossil-calibrated divergence times and ancestral distribution ranges also inferred. Caste presence data, together with ancestral state estimation, suggest that winged reproductive castes are ancestral and retained across the genus, whereas the 2 wingless reproductive castes each evolved only once, with both events occurring simultaneously within a single clade comprising the albipes and strenuus species groups. Overall, the co-occurrence of winged and wingless female-male reproductive pairs in Technomyrmex is rare among ants, highlighting the genus as a promising system for future studies in caste evolution.