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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News

Exceptional diversity of whitefish

Pair of whitefish (C. lavaretus) spawning near the shore in Lac d'Aiguebelette (Photo: Alamy).
May 9, 2025 –

The diversity of whitefish species in Swiss lakes is unique and plays a central role in lake ecosystems. A comprehensive Eawag report now summarises the results of 150 years of research on these fish. They make it clear that the...

The diversity of whitefish species in Swiss lakes is unique and plays a central role in lake ecosystems. A comprehensive Eawag report now summarises the results of 150 years of research on these fish. They make it clear that the mechanisms and environmental conditions that have contributed to their development must be taken into account in order to preserve this species diversity. Last but not least, protecting whitefish diversity helps to preserve the natural yield potential of lakes as a source of food for humans.
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Two new fish species discovered in Swiss waters

Research team taking fish samples in the Langete river using the electrofishing method (Photo: Dario Josi).
February 11, 2025 –

The public can take part in a survey to decide on the names of two fish species discovered by Bárbara Calegari and her colleagues. In this interview, the biologist explains where they live and how to make the diversity of our...

The public can take part in a survey to decide on the names of two fish species discovered by Bárbara Calegari and her colleagues. In this interview, the biologist explains where they live and how to make the diversity of our waters visible.
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Evolution Letters publication from Dr. Alexus Roberts-Hugghis

Figure 1. in Dr. Alexus Roberts-Hugghis publication "A classic key innovation constrains oral jaw functional diversification in fishes"
January 27, 2025 –

Another paper from Alexus showing that the modified pharyngeal jaw, while undoubtedly a functional innovation, at the same time also restricts the diversification of the feeding system.

Another paper from Alexus showing that the modified pharyngeal jaw, while undoubtedly a functional innovation, at the same time also restricts the diversification of the feeding system.
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Biodiversity increases organic nutrient availability across ecosystems

Gebänderte Prachtlibelle, Männchen (lat. Calopteryx splendens, engl. Banded demoiselle) mit ihrer Beute (Foto: Maja Ilić).
October 17, 2024 –

Insects and spiders are superfoods: rich in essential fatty acids and therefore an important food supply for birds, fish, reptiles, amphibians and small mammals.

Insects and spiders are superfoods: rich in essential fatty acids and therefore an important food supply for birds, fish, reptiles, amphibians and small mammals.
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More News from the Department of Fish ecology and evolution

Eawag News

Seminars

31.01.​2026,
9.15 am
Hotel ARTE Olten
FIBER Seminar 2026

"Laichzeit! – Monitoring, Besatz & Aufwertungen – Wo sollen wir ansetzen?"

Latest Publications

Ahi, E. P., Verta, J. P., Kurko, J., Ruokolainen, A., Singh, P., Debes, P. V., … Primmer, C. R. (2025). Brain-associated alterations of Hippo pathway transcription in early maturing Atlantic salmon. BMC Ecology and Evolution, 25, 53 (16 pp.). doi:10.1186/s12862-025-02398-4, Institutional Repository

Background: Pubertal timing is a key life history trait, shaped by ecological pressures to balance reproductive success and survival. Emerging evidence suggests a link between adiposity and early maturation, potentially through hormonal signaling pathways governing puberty timing. The timing of sexual maturation in Atlantic salmon has a strong genetic basis in addition to being linked with environmental shifts and lipid reserves. A gene encoding a co-factor of the Hippo pathway, vgll3, is a major determinant of maturation timing in salmon. The Hippo pathway is known for its evolutionary conserved molecular signal role in both sexual maturation and adipogenesis.
Results: In this study, we tested the expression of Hippo pathway genes in the brain of immature and mature male Atlantic salmon carrying either the early or the late maturation genotype of vgll3. We found increased brain expression of a major Hippo pathway kinase (lats1b) in individuals with early maturation genotypes of vgll3 before maturation development of testes was evident. Moreover, we found components and regulating partners of the Hippo pathway showing differential expression in brain of individuals with early and late vgll3 genotypes prior to maturation. This may suggest a role for the Hippo pathway in central nervous system processes that regulate the preparation for maturation.
Conclusions: This study characterizes transcriptional changes in components of the Hippo pathway in the brain in relation to vgll3-mediated early maturation in Atlantic salmon, highlighting the potential involvement of this pathway in the central regulation of maturation prior to gonadal development.
Ahi, E.  P., & Singh, P. (2025). Emerging orchestrator of ecological adaptation: m6A regulation of post-transcriptional mechanisms. Molecular Ecology, 34(15), e17545 (17 pp.). doi:10.1111/mec.17545, Institutional Repository

Genetic mechanisms have been at the forefront of our exploration into the substrate of adaptive evolution and phenotypic diversification. However, genetic variation only accounts for a fraction of phenotypic variation. In the last decade, the significance of RNA modification mechanisms has become more apparent in the context of organismal adaptation to rapidly changing environments. RNA m6A methylation, the most abundant form of RNA modification, is emerging as a potentially significant player in various biological processes. Despite its fundamental function to regulate other major post-transcriptional mechanisms such as microRNA and alternative splicing, its role in ecology and evolution has been understudied. This review highlights the potential importance of m6A RNA methylation in ecological adaptation, emphasising the need for further research, especially in natural systems. We focus on how m6A not only affects mRNA fate but also influences miRNA-mediated gene regulation and alternative splicing, potentially contributing to organismal adaptation. The aim of this review is to synthesise key background information to enhance our understanding of m6A mechanisms driving species survival in dynamic environments and motivate future research into the dynamics of adaptive RNA methylation.

Research Projects

How will climate change alter the phenology, biomass, and nutritional quality of cross-ecosystem fluxes?

Nutritional phenology with climate change
Coral adaptation to the future climates

simulating response of red sea coral species to rising temperatures
Tropical Reef. Credit Conor Waldock
Simulating the roles of dispersal, thermal tolerance, and adaptive potential in tropical reef fish responses to climate change

simulating tropical fish biodiversity
In this large-scale study we investigate the effects of climate change on fish movement patterns in the Swiss Rhine-Aare River network

Climate change and fish movement patterns

More research projects