Genetic load in Evolutionarily Significant Units (ESUs): conservation and management implications

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. You must log in to post a comment. There are no comments or no comments have been made public for this article. This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. Add a Comment You must log in to post a comment. Comments There are no comments or no comments have been made public for this article. The Conservation Genetics Specialist Group of the International Union for Conservation of Nature (IUCN) proposes introducing Evolutionarily Significant Units (ESUs) as an additional new assessment unit in the IUCN Red List and Green Status. This proposal is made because ESUs possess unique evolutionary trajectories present within species and harbour genetic diversity that requires safeguarding. Given that genetic diversity is not formally incorporated in the Red List or Green Status assessment, the inclusion of ESUs would help improve the protection of valuable intraspecific biodiversity. In this framework, ESUs can be identified by non-genetic and/or genetic data, including data on karyotype differences, distinct adaptations, and deep evolutionary distinctiveness. Genetic load is purposefully not included in ESU delineation, even though its important role in species conservation and management is increasingly recognised. Here, we report on the discussion that led to this decision, explaining the rationale and challenges that led us to exclude the genetic load from the ESU-defining framework. We also discuss recent research on genetic load, and how this could help advance conservation science and improve species conservation and recovery programs. https://doi.org/10.32942/X2WD2K Biodiversity, Ecology and Evolutionary Biology, Genetics and Genomics, Life Sciences Genetic load, Evolutionarily Significant Unit, conservation policy Published: 2025-05-06 00:25 Last Updated: 2025-05-06 00:25 CC-BY Attribution-NonCommercial 4.0 International Conflict of interest statement: None Data and Code Availability Statement: Not applicable Language: English