Genetic diversity hotspot at the edge of the species range: integrating plastome phylogeography with ecological niche modelling for the conservation of Ulmus glabra Huds. in the Italian peninsula

The strong genetic and ecological divergence between U. glabra lineages underscores the need for lineage-specific conservation. Priority actions should include expanding in situ conservation in the Alps, establishing Genetic Conservation Units in the identified climate-refugia and enhancing connectivity in south-central Italy. As a complementary measure, ex situ conservation should maximize genetic diversity, preserving all identified haplogroups.