Evolutionary Ecology

The Division of Evolutionary Ecology is interested in understanding both the proximate genetic mechanisms and ultimate ecological causes of evolutionary processes, such as adaptation to divergent environments, the formation of new species, and the evolution of sex chromosomes. Our main model system is a small fish called the threespine stickleback (Gasterosteus aculeatus) and its close relatives in the stickleback family (Gasterosteidae). These fish have adapted to a variety of marine and freshwater habitats across the Northern hemisphere and consequently evolved incredible diversity in their behaviors, morphologies, life histories, and sex chromosomes on a relatively short evolutionary time scale. The development of genetic and genomic tools for these fish has allowed us to identify specific genetic, genomic, and molecular changes that underlie this phenotypic diversity and that contribute to reproductive isolation between phenotypically and ecologically divergent populations.

News

Research

Our research featured in new documentary on rapid evolution

Our research on rapid evolution in sticklebacks from Haida Gwaii, Canada was featured in a new ARTE documentary called “Darwin Express”! This documentary shows how both plants and animals are evolving rapidly in response to human-mediated disturbances to the environment, such as hunting and fishing, pollution, and invasive species. We are studying just how this can happen, taking advantage of an experiment started by Prof. Tom Reimchen (University of Victoria) on Haida Gwaii: he took sticklebacks from large, deep lakes where the sticklebacks are adapted to feeding in the open water and put them in small ponds where sticklebacks now need to feed on resources found in the near shore environment. In just under 30 generations, the sticklebacks have changed in many traits important for feeding and defence against predators. Together with our colleague Andrew Hendry (McGill University), we are testing the extent to which genetic changes and phenotypic plasticity are responsible for these rapid phenotypic changes. We thank the creator of this documentary, Elena Sender, for including our work and making the filming such a fun and interesting experience. We also congratulate her on a wonderful achievement!

Catherine Peichel

Research

Genetic basis for repeated evolution of plumage coloration in wheatears

How does genetic architecture constrain evolutionary trajectories? To address this question, recently graduated PhD student Dave Lutgen, Reto Burri (Vogelwarte), Manuel Schweizer (Natural History Museum Bern) and many international colleagues inferred the genetic architecture of convergent plumage coloration and its evolutionary history in wheatears. In focal species of the hispanica complex, throat coloration is polymorphic black or white, whereas mantle and neck sides are divergent black or white between species. GWAS leveraging the polymorphism and hybridization show that color variation is explained by a single gene, ASIP. The black-or-white throat polymorphism is explained by the interaction of a transposable element (an LTR retrotransposon) upstream of ASIP with ASIP coding variation. Mantle and neck side coloration is encoded by additive effects of regulatory variants upstream of ASIP. White throat, mantle, and neck side coloration evolved in O. melanoleuca and from there introgressed into O. hispanica. White-throated O. pleschanka feature the introgressed white coding variant but not the LTR, suggesting ASIP is upregulated by undetected variation. Finally, analyses of stable isotope signatures in blood associate white-throated individuals with food intake from a narrower and lower tropic niche than black-throated individual. This suggests that white throat coloration is associated with a specialized foraging niche. Wheatear coloration thus illustrates that by a modular architecture, phenotypes can be decoupled within the constraints of a monogenic architecture, provided enough time for recombination. In this context, hybrid zones represent important melting pots for evolutionary tinkering. Finally, wheatear coloration showcases that evolution makes use of all variation it has at hand, highlighting humanity’s responsibility to conserve a maximum of genetic, phenotypic, and species diversity possible.

Catherine Peichel

Research

When coexistence creates new species

A small ecological difference with a big evolutionary impact: A study led by the University of Bern shows that the presence of just one additional fish species is enough to trigger the formation of new stickleback species.

Catherine Peichel

Research

Ben Sulser obtains funds from the Burgergemeinde Bern.

Investigating Morphological Adaptation in Naturally Evolving Populations of Stickleback Fish:
The research provides insights into evolutionary predictability and refines data pipelines for high-throughput morphometric analyses, making large-scale evolutionary studies feasible using geometric morphometric techniques.
The project promotes collaboration within the University of Bern and supports public science engagement (e.g., Pint of Science, Nacht der Forschung) and is also financially supported by the Burgergemeinde Bern.

Jolanda Paganoni Zurbrügg

Research

Can we predict speciation?

In honor of the precisely predicted total solar eclipse that indeed occurred today in North America, Marius Roesti and colleagues explore the question of whether speciation is predictable. In a new paper for the Cold Spring Harbor Perspectives in Speciation volume, Marius and colleagues explore the general limits of predictability, the value of making predictions, and how to move from hypothesis to a predictive model of speciation. Check it out for a fun and thought-provoking read (and to learn what an orrery is). If you are interested in discussing the topic of predictability in evolutionary biology, check out the symposium "Empirical and Conceptual Insights
on the (Un)Predictability of Evolution" that Marius is organizing at the upcoming Joint Congress on Evolutionary Biology in Montreal!

Catherine Peichel

Congratulations!

Majda Bohutínská wins the John Maynard Smith Prize from the European Society for Evolutionary Biology!

Dr. Magdalena (Majda) Bohutínská, a Marie Skłodowska-Curie Actions postdoctoral fellow in the Division of Evolutionary Ecology and at Charles University in Czechia, has won the 2024 John Maynard Smith Prize from the European Society for Evolutionary Biology (ESEB)! This prize recognizes an outstanding young evolutionary biologist and is named after John Maynard Smith, an eminent evolutionary biologist and former President of ESEB. Majda's unlimited creativity, energy and enthusiasm for biology are an inspiration for all of us, and we are very lucky to have her as our colleague here in Bern! Majda will give the 2024 John Maynard Smith Prize Lecture at the next joint Evolution meeting, held in July 2024 in Montreal, Canada.

Catherine Peichel

Research

Divergence time shapes gene reuse during repeated adaptation

Majda Bohutínská led a new review that appears in the April 2024 issue of Trends in Ecology & Evolution. In this review, she analyzed nearly 30 case studies in which independent lineages have repeatedly responded to similar environmental changes ('repeated adaptation'). She finds that divergence time among lineages is a key factor driving the extent to which the same genes are involved in repeated adaptation ('gene reuse'). Specifically, more recently diverged lineages exhibit higher gene reuse. Majda proposes that this is likely because as lineages diverge, there is a reduction in allele sharing, functional divergence among genes, and changes in genome architecture. However, she highlights that the relationship between gene reuse and divergence time is complex, and that more work in needed in the future to predict the genetic basis of adaptation. Her beautiful review is accompanied by a beautiful cover image of Majda's favorite study system Arabidopsis arenosa, in which three mostly lowland lineages (bottom row) have repeatedly adapted to the alpine environment (top row). It's not sticklebacks, but still pretty cool!

Catherine Peichel

Congratulations!

Katie Peichel elected to the US National Academy of Sciences

Today Katie learned that she was elected by her peers to the US National Academy of Sciences “in recognition of her distinguished and continuing achievements in original research”. It is an amazing honor, not only for her, but for all the technicians, bachelors students, masters students, PhD students, postdoctoral fellows, and collaborators who have brought their creativity, ideas, passion and hard work to our group for the past 20 years!!! Together we have done some great science, and most importantly, we had fun doing it while caring for each other! And, we are not done - the best is yet to come…

Research

Phenotypic species divergence driven by resource competition and shared predation

In a new paper published in Ecology Letters, Marius Roesti and colleagues compared co-occurring (sympatric) and allopatric populations of both threespine stickleback and prickly sculpin fish. They find phenotypic shifts in opposite direction between the species when sympatric. These shifts are seen in typical trophic traits and diet, as well as in traits providing protection against predation. This study suggests that ecological character displacement driven by resource competition has increased vulnerability of one species but decreased vulnerability of the other species to a shared predator (trout). Overall, this study highlights the importance of the indirect interaction via shared predators for driving divergence between prey species.

Catherine Peichel

Contact

University of Bern
Evolutionary Ecology Lab

Baltzerstrasse 6
3012 Bern