Department Fish Ecology and Evolution

Fish Ecology & Evolution (FishEc)

We study ecology, evolution and biodiversity of fishes and other aquatic organisms. We are interested in the mechanisms that drive the origins, the maintenance and the loss of species, genetic and functional diversity.


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The superfast radiations of Lake Victoria and Lake Malawi are marked in green. The photos give an impression of the morphological diversity of the cichlids. (Graphic: Matthew McGee et a., Nature 2020)

August 26, 2020

Explosive diversification explained by network analysis

Using genomic analyses of 100 cichlid species, scientists from Eawag and the University Bern, together with co-workers in Australia, the UK, Tanzania, Uganda and the US, have investigated the striking variation observed in cichlid fish speciation rates. Their findings show that exchanges of genetic variants between existing species dramatically accelerate the development of new species – given favourable ecological conditions. Read more

Original publication

June 24, 2020

Rapid generation of ecologically relevant behavioral novelty in experimental cichlid hybrids

Interspecific hybrids can have transgressive phenotypes that may allow them to explore novel ecological niches. Using a combination of behavioral assays, morphometric analyses, and genetic mapping, we demonstrate transgressive segregation in morphology and in a novel trophic behavior in F2 hybrids between two generalist cichlid species from Lake Malawi. Such rapid generation of novel ecologically relevant phenotypes might contribute to the rapid generation of ecological diversity in cichlid fish adaptive radiations. Read more

May 28, 2020

Genetics of nuptial coloration facilitates the persistence of co-occurring species

Around 500 different cichlid species are found in Lake Victoria. According to a study by scientists at Eawag and Bern University, whether closely related species can persist within the same area depends on the effect sizes of individual genes underlying key mate-choice traits. Read more

Latest Publication

Kagawa, K.; Seehausen, O. (2020) The propagation of admixture-derived adaptive radiation potential, Proceedings of the Royal Society B: Biological Sciences, 287(1934), 20200941 (9 pp.), doi:10.1098/rspb.2020.0941, Institutional Repository

Research Projects

We investigate the mechanisms of speciation and adaptive radiation
Genome evolution and genomic divergence across the Swiss Alpine whitefish radiation
Investigating the interactions between migration ecology, local adaptation and diversification