Phylogeography of Scarturus williamsi and Climate Change Impacts: Genetic Diversity and Projected Habitat Loss in Anatolia

<i>Scarturus williamsi</i> (Williams' jerboa) is a medium-sized, semi-fossorial rodent endemic to steppe ecosystems across Anatolia, Iran, and Azerbaijan, with specialized habitat requirements in semi-arid continental environments. This study integrates a mitochondrial DNA analysis with species distribution modeling to assess the species' evolutionary structure and vulnerability to future climate change. The phylogeographic analysis and species distribution modeling reveal the evolutionary history and climate vulnerability of <i>Scarturus williamsi</i> across Anatolia and adjacent regions. The mitochondrial DNA analysis of 98 individuals demonstrates exceptional haplotype diversity (Hd = 0.9896), with 90 unique haplotypes and complete regional isolation, indicating pronounced population structuring across five evolutionary lineages: Central Anatolia, Eastern Anatolia, Aegean, Black Sea, and Azerbaijan-Iran. The Iran-Azerbaijan lineage exhibits the deepest evolutionary divergence, while Eastern Anatolia functions as the primary Anatolian refugium and Central Anatolia as the secondary refugial center. The strong isolation by distance (r = 0.735, <i>p</i> < 0.001) across ~2500 km explains 54.0% of the genetic variation, with the hierarchical structure reflecting greater Iran-Turkey isolation than intra-Turkish differentiation. The species distribution modeling identifies the Mean Temperature of Driest Quarter (bio9) and the Mean Diurnal Range (bio2) as primary habitat determinants, with bimodal preferences reflecting highland versus steppe adaptations. Climate projections reveal severe vulnerability with habitat losses of 63.69-98.41% by 2081-2100 across emission scenarios. SSP3-7.0 represents the most catastrophic scenario, with a severe habitat reduction (98.41% loss), while even optimistic scenarios (SSP1-2.6) project a 60-70% habitat loss. All scenarios show accelerating degradation through mid-century, with the steepest losses occurring between 2041 and 2080. Projected eastward shifts face constraints from the Anatolian Diagonal, limiting the climate tracking capacity. Despite occupying open landscapes, <i>S. williamsi</i> exhibits exceptional sensitivity to climate change, with Anatolian refugial areas representing critical diversity centers facing substantial degradation. Results provide baseline genetic structure and climate vulnerability information for understanding climate impacts on <i>S. williamsi</i> and Irano-Anatolian steppe fauna.