A practical framework for identifying genetic subpopulations and ESUs: insights for IUCN assessments and broader management

Julia Caroline Geue , Laura Bertola , Bloomer Paulette, Anna Brüniche-Olsen, Jessica da Silva, J. Andrew DeWoody, Ancuta Fedorca, José A. Godoy, Catherine E. Grueber, Maggie Hunter, Christina Hvilsom, Isa-Rita M. Russo, Evelyn L. Jensen, Alexander Kopatz, Anna J MacDonald, Silvia Pérez-Espona, Antoinette J. Piaggio, Jennifer C. Pierson, Helen Senn, Gernot Segelbacher, Paul Sunnucks, Cock van Oosterhout, Deborah M Leigh

Species conservation assessments, such as the International Union for Conservation of Nature (IUCN) Red List and Green Status of Species, guide global conservation priorities by evaluating species’ extinction risk and recovery status. Although such frameworks provide scope to include genetic information, this aspect of biodiversity, which is critical for species’ fitness and adaptive potential, remains underrepresented. The Kunming–Montreal Global Biodiversity Framework now explicitly highlights genetic diversity, offering an opportunity to strengthen its integration into these assessments. While the IUCN can account for subpopulations, these units are rarely applied, and Evolutionarily Significant Units (ESUs) remain formally unacknowledged. Incorporating these genetic units could enhance representation of adaptive genetic diversity and better inform conservation planning and decision-making, though defining them can be difficult when data are limited. We propose a flexible framework that integrates molecular and non-molecular evidence to identify subpopulations and ESUs across taxa and contexts.