The Importance of Karstic Aquifers for the Past and Future Survival of Groundwater Amphipods

Aim: Genetic diversity is key to the long‐term maintenance and adaptability of species to changing environments. While for above‐ground ecosystems, the monitoring and understanding of genetic diversity has advanced substantially, some less accessible ecosystems and their organisms have been largely overseen. This is particularly the case for groundwater organisms. It is not only difficult to collect sufficient genetic data to identify spatial patterns but they may also have been experiencing very different drivers to population size, occurrence, and genetic structure due to very limited dispersal capacity and persistence in areas extending glacial cycles. Location: Switzerland. Methods: Here, we use a unique and spatially highly resolved data set containing a representative collection of thousands of Niphargus amphipod individuals across Switzerland. We analysed the genetic structure of ~1300 individuals of five species within their contemporary distribution. Results: We found a significantly higher diversity in karstic aquifers and a correlation between the genetic diversity of a species and the proportion of its distribution in the karst. Main Conclusions: This identifies karstic ecosystems as specific targets for future conservation programmes but also indicates that these karstic areas could have been possible refugia of Pleistocene persistence. Being epicentres of genetic diversity, the protection of the karst is also central for the maintenance of groundwater organisms' adaptive potential to future climatic changes.