Latitudinal clines in gene flow and demographic stability reveal drivers of microendemism in a radiation of alpine grasshoppers

Understanding the geological, ecological, and microevolutionary processes that shape range size in alpine organisms is key to explaining the high rates of local endemism that characterize mountain ecosystems. Here, we investigate the geography of speciation in Oropodisma, a radiation of alpine grasshoppers from the Balkan Peninsula that includes several narrow-endemic species distributed along a latitudinal gradient of > 600 km. Phylogenomic-based species delimitation clarified taxonomic uncertainties and revealed striking variation in range size, with the northernmost species occupying an area nearly as large as all other congeneric taxa combined. Phylogenetic network analyses and divergence dating indicate a Pleistocene origin for the group, with recent speciation events (