I am a senior postdoctoral researcher at the University of Bern and Eawag (Group Seehausen), both in Switzerland, studying organismal diversification, especially in the context of cichlid fish adaptive radiation. I'm currently using a paleogenetic approach to investigate Lake Victoria's haplochromine cichlids, funded through an SNSF Sinergia grant.
In previous work, I explored patterns of ecological specialisation and genomic divergence of Timema stick insects together with Patrik Nosil at the University of Sheffield, UK, and speciation and ecomorphological evolution of cichlid fishes in the groups of Axel Meyer (University of Konstanz, Germany) and Walter Salzburger (University of Basel, Switzerland).
New paper: A continuous fish fossil record reveals key insights into adaptive radiation
Proud of Nare for seeing through this fantastic study, now published in Nature, which required endless hours of tedious screening of sieve fractions. The more than 7000 tiny fish fossils from the sediment of Lake Victoria now illuminate the early stages of adaptive radiation of haplochromine cichlids there. The continuous record of fish remains spans from the beginnings of Lake Victoria ~17 ka to modern times and emphasises ecological versatility as a likely prerequisite for adaptive radiation. When the lake got deep and an open water habitat formed (~13 ka) a stark shift can be observed in the fish community. Haplochromines remain abundant in the deep water habitat, while other fish lineages become much less abundant and are largely constrained to littoral and sub-littoral habitats.
New paper: Ancient DNA is preserved in fish fossils from tropical lake sediments
In this new paper in Molecular Ecology, we show for the first time that fish fossils from tropical lake sediments yield endogenous ancient DNA. Despite generally low endogenous content and high sample drop-out, high-throughput sequencing and in some cases sequence capture allowed for taxonomic assignment to family or tribe level and phylogenetic placement of individuals. Even skeletal remains weighing less than 1 mg and up to 2700 years of age could be phylogenetically placed. Success rates and aDNA preservation differed between the investigated lakes Chala, Kivu and Victoria, possibly caused by differences in water oxygenation at deposition. Our study demonstrates that sediments of tropical lakes preserve genetic information on rapidly diversifying taxa over time scales of millennia.
New paper: A chronologically reliable record of 17,000 years of biomass burning in the Lake Victoria area
Through the diligent work of Yunuén and co-workers, we can present the first continuous sedimentary charcoal records from Lake Victoria and a cutting-edge age model to boost. Charcoal data suggest that fire activity varied substantially during the past 17,000 years, and our new pollen records reveal the long-term vegetation dynamics. We infer that before human impact increased during the Iron Age (ca. 2400 yr BP), biomass burning was linked to climate and vegetation reorganizations, such as warming, drying, and the expansion of rainforests and savannas.
New paper: The mitochondrial genome of the red icefish (Channichthys rugosus) casts doubt on its species status
In Polar Biology, my co-authors and I report the mitochondrial genome sequence of the antarctic ice fish Channichthys rugosus. We pieced it together from extremely short DNA fragments from an almost 50 year old, formalin-fixed museum specimen. This was made possible through application of ancient DNA methods, such as single-stranded DNA library preparation.
Conference symposium: "Paleolimnology in an evolutionary context"
At the INTECOL conference 2022 in Geneva, Nare Ngoepe, Ole Seehausen and I organised a session on "Palaeolimnology placed in an evolutionary context" with great contributions on a variety of systems.
Conference marathon
Far4ViBE, SIAL8 and ICDP workshop on Lake Victoria drilling. Busy times during field work and three events back-to-back in Tanzania. Was great to catch up with many colleagues and make new connections – and say hi to Lake Tanganyika's fabulous cichlids once again.
Conference: ISBA9
ISBA9 conference The International Symposium of Biomolecular Archaeology is on again, and this time I'm participating. Great to see what fantastic findings can be created with paleoproteomics and ancient DNA from tiny amounts of diverse substrates.
Teaching: Practical in Aquatic Ecology & Evolution 2020
During this year's two weeks long intensive practical we will investigate fish adaptive radiations using geometric morphometrics and phylogenetic comparative methods.
New paper: Large scale mutation in the evolution of a gene complex for cryptic coloration
New paper: Large-scale mutation in the evolution of a gene complex for cryptic coloration. Published in Science
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New paper: Adaptive zones shape the magnitude of premating reproductive isolation in Timema stick insects. Published in Philosophical Transactions of the Royal Society B
Teaching: Practical in Aquatic Ecology & Evolution 2019
Practical in Aquatic Ecology & Evolution During this year's four weeks long intensive practical we will investigate the fish community composition in Lake Constance through time using sediment cores.
Project starting: Lake Victoria's paleohistory under the magnifying glass
SNSF Sinergia grant is starting in March 2019. Last November, we received the great news that our application for an interdisciplinary Sinergia grant was approved by the Swiss National Science Foundation, and the project starts already this month. Over the next four years, our large team of collaborators will investigate Lake Victoria's prehistory with a focus on how the diversification of haplochromine cichlids interacted with changes in the ecosystem. You can find more information on the SNSF's project database (link).
Expedition: Sediment coring on Lake Victoria
Coring expedition to Lake Victoria Just returned from the shores of Lake Victoria, Tanzania, where a team from Tafiri, Uni Bern (IPS and IEE), and Eawag retrieved a large set of sediment cores covering the entire life time of the modern lake (i.e. ~15000 years). A great team working very hard and some luck with wind conditions made this possible. The expedition was funded by an University of Bern Strategy Grant.