Evolution of <i>Crematogaster sordidula</i> (Hymenoptera, Formicidae) Ants in the Mediterranean Region During Plio‐Pleistocene Climatic Changes

ABSTRACT Understanding insect responses to global climate change involves identifying strategies used during past climate oscillations. Phylogeography offers a powerful framework to unravel how historical climatic and geological events have shaped the spatial genetic patterns of species, providing critical insights into evolutionary processes, whereas population genomic approaches enable finer‐scale resolution of demographic history and genetic connectivity. We focus on an abundant ant species, Crematogaster sordidula , endemic to the Mediterranean region, a biodiversity hotspot experiencing faster warming than the global average. Using a phylogenomic dataset of ultraconserved elements (UCEs) from 123 individuals, we reconstructed population‐level relationships with maximum‐likelihood and coalescent methods and estimated a time‐calibrated phylogeny to investigate the timing of major divergence events. We inferred population structure by generating mitochondrial haplotype networks and analysing admixture and regional genetic diversity and differentiation on the basis of SNPs obtained from UCE data. We recovered four major lineages that diverged during the Pliocene: a Western Mediterranean clade, an Eastern Aegean region clade, an Anatolia‐Türkiye clade, and a Central‐Eastern Mediterranean clade, with the latter three together forming a larger Eastern Mediterranean clade. This population structure confirms the east–west distribution pattern found for many taxa in the Mediterranean. Genetic diversity was highest in southern regions, supporting the hypothesis that these areas acted as refugia during Pleistocene climatic oscillations. Within the Eastern Mediterranean clade, population structure and gene flow indicate complex demographic histories possibly shaped by the region's dynamic palaeogeography and paleoclimatic history. Together, these results provide a foundation for understanding the species' potential responses to ongoing environmental changes.