Trends in hidden taxa and habitats – understanding the extent and impact of the biodiversity crisis

The vast majority of insect species are believed to be undescribed, yet they exhibit some of the largest reported losses in biomass, even in protected areas. As such, they exemplify the idea of an unknown, “hidden” group. We do not know to what extent declines in biomass correlate with declines in species richness, how these changes might affect ecosystem functioning, or which landscapes show higher losses of insect biodiversity. The project “unknown Germany” addresses this gap by re-analyzing the valuable Krefeld collection, which used standardized Malaise trapping to sample flying insect diversity across a variety of ecosystem types in Germany over the last 30 years. In this project, a total of around 400.000 specimens will be analyzed by sequencing the CO1 barcoding gene in applying high-throughput methods on material from two time points showing a significant decrease in biomass. This allows us exploring the links between biomass and biodiversity and identifying changes in several levels of species diversity, phylogenetic diversity, and community composition. Traits and ecological roles (such as pollinator, predator, etc.) from well-known species will be imputed to assess how changes over time within different functional groups may impact overall ecosystem functioning. Functional diversity and composition will be studied to

compare specialists with generalists, examine the presence of non-native species, and analyze alterations in food web structure. This sampling scheme will enable the detection of shifts at the community level, either through actual species loss or phenological changes—when shifts in the timing of species activity alter ecosystem service provision. In particular, the first quantification of trends in species-level diversity and their connection to ecosystem services will be provided by this project—an area that, until now, has only been hypothesized based on biomass changes and remains untested. The results will advise conservation legislators on how to support biodiversity resilience and ecosystem services in addressing diversity besides “iconic” species conservation methods are usually focusing.