Aquadiverse

Towards an Evolutionary Biodiversity Framework through integrating ecology, population genetics and conservation biology in a spatially explicit context

Biodiversity management and conservation is one of the few global political goals that have been agreed upon at the highest possible political level. “Common wisdom” is that well-developed countries, such as Switzerland, are at the forefront of “the biodiversity issue”, setting examples for having their biota well documented and for enforcement of local management and conservation practices at the national level. Against this background, the recognition that aquatic biodiversity in Switzerland, even of key groups such as commercially important fish, is poorly known is highly alarming. Lack of knowledge of native diversity effectively prevents recognition of the magnitude of the problem that rapid environmental change and habitat loss enforce on aquatic biodiversity in Switzerland.

At the same time, Switzerland provides some of the best documented time-series of aquatic ecosystems, potentially reporting some of the changes in biodiversity and the physico-chemical factors coinciding with that change. These time-series data, some of which are in-house at Eawag, provide an excellent opportunity to reach back in time and examine how past changes in the environment have reflected on the present biodiversity. Also, recent advances in techniques of sediment coring and molecular biology now allow us to reach back in evolutionary time by extracting DNA from past generations of aquatic organisms. The state-of-the-art in molecular biology therefore allows us to link change in species diversity to genetic and evolutionary change that has taken place within populations, driven by gene flow and local adaptation to changing environments. Together, these different aspects provide a unique opportunity to identify principle relationships between environments, genes and species diversity, and with these understand and predict future biodiversity change in Switzerland and beyond.

Relationships between genetic diversity, environmental heterogeneity and species diversity are poorly known, and empirical data and theory development are urgently required. This is why several Swiss research groups came together to develop the (initially) three years research project AQUA DIVERSE, funded by the Swiss Institute for Aquatic Science and Technology (Eawag).

The aquatic biota of Switzerland is uniquely suited to enable real progress towards the identification and quantification of the above discussed fundamental relationships. It is young in geological/evolutionary terms, having constituted itself after glacier retreat just 12,000 to 15,000 years ago. Biodiversity is a function of genetic diversity and environmental heterogeneity and alpine aquatic habitats have much of both: steep elevation gradients and inclination-dependent local climates that range from arctic-alpine to Mediterranean create an unusually heterogeneous environment that requires a diverse range of local adaptations at small to very small spatial scales. Genetic diversity in postglacial systems depends on the distance to glacial refugia, and the Swiss Alps have been colonized by lineages from Danubian, Mediterranean and Atlantic refugia. As a result, the Alpine region of central Europe is unusually rich in aquatic biodiversity, and Switzerland is unique because it harbors the distinct evolutionary diversity of each of Europe’s four largest drainage systems: Rhine, Rhone, Po and Danube. Within each system, Swiss aquatic habitats range from alpine glacier rivers and ice-covered lakes to low-elevation lakes and rivers. Because many of these habitats were inaccessible before deglaciation (14-10kyr bp), much of the ecological diversity of aquatic organisms is young in evolutionary terms. For example, many superficially similar species of salmonid fishes have only recently been recognized, despite representing ecologically important adaptive diversity. The combination of colonization from several genetically distinct glacial refugia on the one hand, and recent ecological diversification on the other hand, makes Swiss aquatic biodiversity globally unique.

Aquatic biodiversity is being lost rapidly in Switzerland, yet the causes of decline are rarely understood. For example, Swiss lakes contain important adaptive radiations of salmonid fishes, yet at least 20-30% of the diversity of endemic whitefish (Felchen), char (Saibling) and trout (Forelle) has been lost in the past 50 years. Climate change, changes in nutrient regimes and habitat loss are primary factors that affect species diversity worldwide, and it is likely that these are main causes of diversity loss in Switzerland. An additional major factor is human management of populations through stocking (fish) and introduction of non-native species. However, how and how rapidly these man-made changes of the environment contribute to biodiversity loss in Switzerland is not well understood. Even less clear is how to predict changes in biodiversity, how to optimize management practices of aquatic ecosystems to maintain biodiversity, and how to remediate endangered aquatic biodiversity in the face of rapidly changing environments.

In AQUA DIVERSE we aim at quantifying, explaining and conceptualizing loss of aquatic biodiversity in Switzerland, which is clearly the necessary first step towards finding solutions for sustainable biodiversity management in the crossfire of global environmental change and local socio-economic constraints.

• Contact person:
  Ole Seehausen
  
  
• Leading research groups
  Group Seehausen
  Group Jokkela
  
  
• Participating research groups
  Group Spaak
  Group Robinson
  Group Mathews
  Group Schubert
  
  
• Funding: Eawag