Adaptation along elevational gradients - depth and altitude

bullhehad by Ole Seehausen

Biodiversity is broadly affected by climate warming, eutrophication, habitat loss, and invasive species. All of these have severe effects on biota of high elevation biomes. The Alps in southern Central Europe are home to such biomes. Rivers and streams and the deep waters of the large lakes of the Alps are characterized by cold water year round. Consequently, they lack most of the warm water fish of the European lowlands. Streams are dominated by trout (Salmo spp.), and bullhead or sculpin (Cottus gobio complex). The deep cold zones of lakes are dominated by whitefish (Coregonus spp.), char (Salvelinus spp.) and bullhead. All of these taxa are highly diversified in Switzerland with phenotypically and genetically distinct populations and species in different streams and lakes, and they are key players in the alpine aquatic ecosystems. 

To protect and sustainably manage such endemic diversity and to maintain ecosystem function, we need to understand both the distribution of genetic and functional diversity and adaptation and the processes promoting and eroding diversity and adaptive potential. We have demonstrated potentially adaptive genetic differentiation between high and low elevation trout populations within the same streams, but also large scale loss of old genetic and functional diversity  through massive introgression of indigenous trout species due to stocking with Atlantic trout. We ently investigate effects of such gene flow on adaptation using next generation sequencing. We have also shown that several phenotypically and genetically distinct types of bullhead can coexist, occupying lakes or streams, and can even coexist within the same streams. We currently study these using next generation sequencing. 

In the lakes we investigate the genetic background underlying phenotypic diversity and adaptation in char and whitefish. We use next generation sequencing, microsatellite markers and phenotype analysis.


Major projects

AquaDiverse was funded by Eawag over several years and contributed importantly to our early work on the adaptive diversity of whitefish in the deep lakes of the Alps.

BioChange built on AquaDiverse and extended the work to alpine streams and different groups of organisms. Our part was the fish: trouts and bullheads. The funded phase of the project ended several years ago and was funded by the ETH Competence Center for Environment and Sustainability (CCES). The goal of BioChange was to use evolutionary and ecological parameters estimated in natural populations and data on environmental change to build predictive models of biodiversity change.

GeneMig followed on BioChange and was an inter- and transdisciplinary research project that assessed challenges of migration (i.e. species and their genes) in a chang­ing environment for society and environmental management. The project merged concepts and expertise of two successful CCES projects (ENHANCE, BioChange) and CCES-initiated facilities (Genetic Diversity Centre, field sites).

Based on state-of-the art social scien­ces methods, genetic analysis, landscape modeling, and field experiments, two scientific goals were and are still being addressed:
(1) identification of the public awareness of risks and challenges related to species migration in a changing environment;
(2) analysis of how natural and unintentional range shifts in common and invasive species and deliberate movement of a commercially interesting spe­cies (stocking) affect local populations in a changing environment.

An outreach goal assesses the potential to effectively integrate genetic methods into environmental management. Our part was ecological genomic work on adaptation in trout, using next generation sequencing.