Every semester, EES organise a seminar series, which takes place on Mondays at 16:00 at Biozentrum, Room G00.001
Sommer Semester 2026
Hannes Svardal
University of Antwerp - Belgium
Genomic mechanisms of rapid adaptive radiation in Lake Malawi cichlids
Abstract:
How new species arise remains one of the central questions in evolutionary biology. With more than 800 ecologically and morphologically diverse species, the Lake Malawi cichlid radiation provides an extraordinary system to study this process. Previous work has shown that hybridisation between cichlid lineages was common and contributed to diversification by transferring adaptive genetic variation between species. However, hybridisation and recombination can also break apart co-adapted gene combinations and thereby impede speciation.
In this talk, I will present recent work investigating how these opposing effects of hybridisation may be reconciled. Using whole-genome sequencing data from 1375 individuals spanning the Malawi radiation, we identified five large chromosomal inversions — rearrangements that suppress recombination and can maintain adaptive combinations of alleles. These inversions are strongly associated with ecological divergence along depth gradients and show signatures of adaptive evolution in sensory, physiological, and reproductive genes. We further find evidence that introgression of inversion haplotypes coincided with bursts of diversification and that some inversions repeatedly became sex linked in different lineages. Together, these findings suggest that interactions between ecological adaptation, hybridisation, and sex-linked selection played a central role in the evolution of this remarkable radiation.
In the second part of the talk, I will focus more specifically on depth adaptation and visual system evolution in deepwater cichlids. Combining association mapping, selection scans, and transcriptomics, we uncover widespread signatures of adaptation in visual pathways, including green-sensitive opsins and multiple components of the phototransduction cascade. These results point to coordinated evolution of eye morphology and visual molecular pathways during adaptation to deepwater habitats and highlight the importance of sensory evolution in ecological diversification.
Host: Michael Matschiner
Previous and future talks in the EES seminar series