Department Fish Ecology and Evolution

Conservation Biology

The state of conservation biology is most often defined in terms of what is known about terrestrial ecosystems. Contrary to what can sometimes be read in that literature, the largest stumbling block on the way to successful biodiversity management and conservation in aquatic ecosystems is the lack of quantitative baseline data, and the associated ignorance about diversity under the water surface. In the absence of data, goals are often set as qualitatively defined “reference conditions”, an approach that can be subjective, that risks broad brush generalisation and suffers from the shifting baseline syndrome. To combat these issues we launched several large integrated biodiversity mapping efforts for fish in Switzerland, Projet Lac in 2010, and more recently Progetto Fiumi.

Our second focus is on the population genetics and ecology of invasion and range expansion on the one hand, and decline and extinction on the other. Here we study Threespined stickleback at the invasion front north of the Alps and at the extinction front south of the Alps, and we study rheophilic fish species that are rapidly declining and approaching extinction in Switzerland.


Current projects

Projet Lac

In Projet Lac  we collect and compile quantitative baseline data for most large lakes of Switzerland and neighboring countries. We designed methods for a full quantitative sampling design and applied them to twenty six medium to large and deep to very deep lakes. Our aim is to document and assess fish diversity at all its fundamental levels. This includes individual genetic and phenotypic diversity for key taxa, species diversity and abundance, community diversity by habitats and whole lake diversity. A large state-of-the-art collection of pre-alpine fish is being established at the Natural History Museum in Bern. We are now analyzing the species distribution and abundance data and are beginning to collect phenotypic and genetic data. Eventually we will use the data to try and explain some of the large changes in species diversity and distribution observed over the last decades, and we want to understand if these changes affect ecosystem functions. Progetto Fiumi is built to achieve the same for many streams and rivers in Switzerland.


Alexander, T. J.; Vonlanthen, P.; Périat, G.; Degiorgi, F.; Raymond, J.-C.; Seehausen, O. (2015) Evaluating gillnetting protocols to characterize lacustrine fish communities, Fisheries Research, 161, 320-329, doi:10.1016/j.fishres.2014.08.009, Institutional Repository



Documenting endemic whitefish species and developing a management scheme

After a decade of research in our group on the distribution, origin and loss of endemic whitefish in the northern prealpine lakes of Switzerland we have now entered a phase, where we want to compile all we have learned into a compendium for fisheries managers. To make conservation-minded management effective, the species have to be recognized, defined and named. Our research had led to the realization that there are several yet undescribed and unnamed species of Coregonus in Switzerland. We are now in the process of describing these in the context of a systematic revision of the genus in Switzerland.

This is a Bafu/Eawag funded project that we do in collaboration with AquaBios.


Vonlanthen, P.; Bittner, D.; Hudson, A. G.; Young, K. A.; Müller, R.; Lundsgaard-Hansen, B.; Roy, D.; Di Piazza, S.; Largiader, C. R.; Seehausen, O. (2012) Eutrophication causes speciation reversal in whitefish adaptive radiations, Nature, 482(7385), 357-362, doi:10.1038/nature10824, Institutional Repository
Hudson, A. G.; Vonlanthen, P.; Bezault, E.; Seehausen, O. (2013) Genomic signatures of relaxed disruptive selection associated with speciation reversal in whitefish, BMC Evolutionary Biology, 13, 108 (18 pp.), doi:10.1186/1471-2148-13-108, Institutional Repository

Hudson, AG, Vonlanthen, P, Seehausen, O 2011. Rapid parallel adaptive radiations from a single hybridogenic ancestral population. Proc Royal Society of London, Series B. 278, 58-66

Conservation genetics of rheophilic fish of alpine rivers

Several rheophilic fish species of the prealpine grayling and trout zones are experiencing dramatic population declines and rapid population extinction at a stage before quantitative assessment of genetic, functional and taxonomic diversity. Trying to provide such data, we have been studying four taxa. The first was the enigmatic Nase or Nose carp (Chondrostoma nasus), perhaps the most rapidly declining fish of Swiss rivers. We documented a deep genetic break between populations in the Lake Constance drainage and those in the rest of the Rhine catchment. We also demonstrated phenotypic variation, possibly associated with river size, and evidence of a genetic bottleneck in one population. Based on these findings we made recommendations for management.

Further, we are studying grayling populations in some parts of Switzerland in a similar framework, another species that declines for reasons that are not entirely clear. We are studying native trout of Mediterranean lineages, and the conditions of coexistence with or displacement by introduced Atlantic trout. Finally, we study bullhead (sculpins, Cottus gobio), a little benthic species that is of no commercial interest and supposedly has not been much affected by human translocation.


Hudson, A. G.; Vonlanthen, P.; Seehausen, O. (2014) Population structure, inbreeding and local adaptation within an endangered riverine specialist: the nase (Chondrostoma nasus), Conservation Genetics, 15(4), 933-951, doi:10.1007/s10592-014-0590-3, Institutional Repository
Junker, J.; Peter, A.; Wagner, C. E.; Mwaiko, S.; Germann, B.; Seehausen, O.; Keller, I. (2012) River fragmentation increases localized population genetic structure and enhances asymmetry of dispersal in bullhead (Cottus gobio), Conservation Genetics, 13(2), 545-556, doi:10.1007/s10592-011-0306-x, Institutional Repository

Genetics and ecology of invasion and range contraction

We have been working for several years now on the genetics and ecology of invasion of the Swiss midlands by Threespined stickleback. The invasion took place in the last 150 years and was associated with massive expansion of the ecological range of the species. In much of the Mediterranean region, stickleback were simultaneously declining rapidly to the extent that they are extinct or nearly extinct in many places and enjoy protected species status. We have more recently started to work on these isolated Mediterranean relict populations, hoping to make a little contribution to documenting diversity and adaptive potential.



Lucek, K.; Sivasundar, A.; Seehausen, O. (2014) Disentangling the role of phenotypic plasticity and genetic divergence in contemporary ecotype formation during a biological invasion, Evolution, International Journal of Organic Evolution, 68(9), 2619-2632, doi:10.1111/evo.12443, Institutional Repository
Lucek, K.; Sivasundar, A.; Kristjánsson, B. K.; Skúlason, S.; Seehausen, O. (2014) Quick divergence but slow convergence during ecotype formation in lake and stream stickleback pairs of variable age, Journal of Evolutionary Biology, 27(9), 1878-1892, doi:10.1111/jeb.12439, Institutional Repository
Lucek, K.; Lemoine, M.; Seehausen, O. (2014) Contemporary ecotypic divergence during a recent range expansion was facilitated by adaptive introgression, Journal of Evolutionary Biology, 27(10), 2233-2248, doi:10.1111/jeb.12475, Institutional Repository
Lucek, K.; Sivasundar, A.; Roy, D.; Seehausen, O. (2013) Repeated and predictable patterns of ecotypic differentiation during a biological invasion: lake–stream divergence in parapatric Swiss stickleback, Journal of Evolutionary Biology, 26(12), 2691-2709, doi:10.1111/jeb.12267, Institutional Repository
Lucek, K.; Sivasundar, A.; Seehausen, O. (2012) Evidence of adaptive evolutionary divergence during biological invasion, PLoS One, 7(11), e49377 (6 pp.), doi:10.1371/journal.pone.0049377, Institutional Repository
Lucek, K.; Roy, D.; Bezault, E.; Sivasundar, A.; Seehausen, O. (2010) Hybridization between distant lineages increases adaptive variation during a biological invasion: stickleback in Switzerland, Molecular Ecology, 19(18), 3995-4011, doi:10.1111/j.1365-294X.2010.04781.x, Institutional Repository

Lucek, K, Seehausen, O (2015) Distinctive insular forms of threespine stickleback (Gasterosteus aculeatus) from western Mediterranean islands. Conserv Genet, DOI 10.1007/s10592-015-0742-0