Capra ibex was almost wiped out in the 19th century. Today, over 40,000 animals live in the Alps, but all descend from fewer than 100 individuals, which severely limits genetic diversity. Photo: Senckenberg/Leigh.

Genetic diversity is crucial for the survival of species. It strengthens the adaptability, resilience, and long-term stability of populations. An international study published in the journal BioScience has developed a new approach to identify genetically differentiated groups more reliably within a species. The method is intended to improve both the evaluation of extinction risks and the assessment of reintroduction potential in the future. It aims to reduce the loss of genetic diversity by ensuring that genetically unique populations are effectively protected. 

With its Red List of Threatened Species, which comprises more than 163,000 species, the IUCN defines the global standard for assessing extinction risk. Currently, assessments are based on criteria relating to demographic trends and habitat loss and generally derive extinction risk at the species level. Genetically differentiated units within a species are often not considered systematically, and there is a lack of standardized methods for delineating such units. As a result, genetic differences among populations of the same species, which are fundamental for their ability to adapt to environmental change and disease, are often overlooked in these assessments.

The study calls for greater attention to intraspecific units such as Evolutionarily Significant Units (ESUs) and subpopulations. ESUs comprise lineages with very little genetic exchange between them, which have evolved relatively independently and developed unique local adaptations and genetic variants. Identifying these units would help prioritize populations at greatest risk of extinction and enable tailored conservation and management measures, even where genetic information is limited.

The study also highlights that population recovery does not necessarily imply the recovery of genetic diversity. As an example, it cites the Alpine ibex (Capra ibex), whose population has recovered numerically after being brought to the brink of extinction in the 19th century. However, all present-day populations descend from fewer than 100 individuals, resulting in greatly reduced genetic diversity and increased vulnerability to disease and environmental change.

To address this limitation, the international team now presents a standardized framework for identifying and distinguishing both subpopulations and Evolutionarily Significant Units (ESUs). The new concept combines a variety of data sources, including classical genetic analyses, geographical distribution, ecological differences, and traditional and Indigenous knowledge. The aim is to make use of the different types of information available to conservation managers around the world while ensuring consistent standards. According to the study, the approach is currently undergoing extensive testing to facilitate its integration into species conservation assessments, particularly regarding recovery potential and extinction risk.

The authors point out that this approach could contribute to achieving the genetic diversity targets adopted under the Kunming-Montreal Global Biodiversity Framework in 2022. Greater integration of genetic information into conservation planning would enable more effective conservation strategies, improve resource allocation, and strengthen species' capacity to cope with environmental change.

The study was led by Deborah Leigh of the Senckenberg Society for Nature Research (Leibniz Institution for Biodiversity and Earth System Research) and included members of the Conservation Genetics Section of the International Union for Conservation of Nature (IUCN). Researchers from Australia, Denmark, Germany, Great Britain, Norway, Romania, Spain, South Africa and the United States contributed to the work, including José Antonio Godoy from the Doñana Biological Station (EBD-CSIC).