Tage der Biodiversität 2027

Genetic diversity contributes to the long-term adaptability and resilience of populations and species. Yet biodiversity monitoring has traditionally focused on species and habitats without directly assessing genetic diversity. The Kunming-Montreal Global Biodiversity Framework (GBF) now includes genetic diversity in national biodiversity reporting through two indicators: the proportion of populations with an effective population size above 500 (N_e500; headline indicator) and the proportion of populations maintained (PM; complementary indicator). Because direct genetic assessments remain costly and difficult to implement across many species, proxy-based approaches offer a scalable alternative. Here, we developed an automated workflow to reconstruct N_e500 and PM indicators for thousands of species in Switzerland based on >30 million occurrence records spanning the period from 1500 to 2020, in combination with biodiversity monitoring and land-use data. We identified species with sufficient data to support monitoring based on a rarefaction analysis and defined populations through grid-based spatial clustering. We inferred the N_e500 indicator by combining species densities with suitable habitat area and reconstructed historical PM by comparing contemporary and historical population distributions. Across ~1,600 species, the reported N_e500 value was 0.98, while PM was 0.63 for ~4,000 species. This approach was used for Switzerland’s CBD reporting in 2026. This first national reporting cycle provides an important baseline. However, detecting temporal trends would require repeated assessments across multiple reporting cycles, potentially spanning decades. Historical data can therefore provide an opportunity to reconstruct such trends. Our retrospective analysis indicated a 13% population loss over the past century. Declines were up to 1.5 times faster in threatened than in non-threatened species, highlighting the value of retrospective trends for evaluating current genetic-diversity indicators. Our results demonstrate both the opportunities and limitations of proxy-based genetic diversity indicator assessment and provide a historical baseline for interpreting future changes in these indicators.