On Monday 15th June 2026, CIGENE’s Øyvind Sætren Gulbrandsen successfully defended his PhD thesis titled “Function, diversity and evolution of meiotic recombination localization factor PRDM9 in Atlantic salmon”.
Øyvind’s PhD project investigated the diversity and evolution of the PRDM9 gene in Atlantic salmon. The findings reveal that variation in this gene underpin different patterns of recombination that promotes genetic diversity between generations.
In many vertebrates, PRDM9 is known to play a key role in determining where in the genome meiotic recombination occurs. However, the function and evolution of PRDM9 in Atlantic salmon is less well understood. To bridge this knowledge gap, Gulbrandsen sequenced thousands of individuals from both wild and farmed salmon populations, resulting in the largest dataset of its kind.
The results show that different versions of PRDM9 (i.e. with subtle differences in the PRDM9 genetic sequence) give rise to different recombination patterns in the genome. This leads to significant differences between individuals in terms of which combinations of genetic material are passed on to the next generation.
The findings of Gulbrandsen’s PhD project provide important novel insights into how PRDM9 functions in fish. Furthermore, his work implies that the some of the most widely used models scientists have used so far to study PRDM9 evolution do not fully explain the patterns observed in nature. How different populations are structured and connected, and the migration of individuals between populations, may play an important role in the evolution of PRDM9, and these factors should be taken into account in future models.
Gulbrandsen’s main supervisor was Professor Sigbjørn Lien, NMBU, with co-supervisors Professor Matthew Peter Kent, Marie Baudement, and Nicola Barson, all based at CIGENE.
As part of the defence, Øyvind also did a great job presenting his trial lecture, titled “The Evolution of recombination landscapes: Mechanisms, Paradoxes, and the Divergent Paths of Vertebrates”.
The defense evaluation committee comprised Prof. Aurora Ruiz-Herrera Moreno, Universitat Aurenoma de Barcelona (UAB), and Pierre-Alexandre Gagnaire, CNRS, Institut des Sciences de l’Evolution de Montpellier (ISEM), as well as Prof. Peer Berg (NMBU). We thank the committee members for their valuable participation in the defense, and congratulate Øyvind on a successful project and great job in defending the thesis.