Two Master’s thesis topics on Atlantic salmon eco-evolutionary change across Europe at the University of Helsinki
Background: Atlantic salmon (Salmo salar) populations worldwide have faced a decline or have already been extirpated (ICES 2025), mainly due to human-induced pressures over the past two centuries. Alongside these demographic declines, long-term monitoring programs have reported rapid phenotypic changes, including shifts in age at maturity and growth across their North Atlantic distribution (Otero et al., 2012; Erkinaro et al., 2019; Harvey et al., 2021; Vollset et al., 2022). Genetic changes have also been documented, including increasing homogenization among populations (Ostergren et al., 2021). Considering these phenotypic and genotypic traits influence salmon fitness and population resilience, understanding their temporal dynamics is crucial. European populations benefit from long-term monitoring programs, providing a unique opportunity to study temporal trends in life-history and genetic diversity across a broad geographic scale and environmental gradient. Using these datasets, we offer two Master’s thesis projects:
1. Long-term changes in life-history strategies of Atlantic salmon across Europe – Starting date: as soon as possible
• Research questions: What is the extent of life-history diversity across European populations? How have these life-history strategies changed over decades?
• Available data: Life-history traits (age at maturity, age at smoltification, sex, length, and weight) derived from scales and biometric measurements for
approximately 45,000 individuals collected through long-term monitoring (~1973– 2022) across several European populations.
• Student tasks: The student will analyze the already available database to characterize the diversity of life-history strategies across populations and apply statistical time-series methods to quantify phenotypic trends over time. The student will compare trends among populations.
2. Past and present genetic diversity of Atlantic salmon populations across Europe – Starting date: flexible
• Research questions: How has genetic diversity in European salmon populations changed over time? Are populations becoming more or less homogeneous?
• Data available: Genotypic data (140 SNPs) from approximately 11000 historical and contemporary samples, derived from scales collected through long-term monitoring (1956–2022) across multiple European populations.
• Student tasks: The student will assess changes in genetic diversity, structure, and effective population size (Ne) over time in several European populations using standard population genetic methodologies.
Supervisors
Dr. María Cádiz Escobar – maria.cadiz-escobar@helsinki.fi: Postdoctoral researcher with interests in population genetics, genomics, evolution, conservation, and bioinformatics (Cádiz et al. 2020, 2024, 2025). Maria is currently studying the population and evolutionary genetics of large-effect life history-linked genes using long-term time series of European Atlantic salmon populations.
Dr. Amaïa Lamarins (amaia.lamarins@helsinki.fi): Postdoctoral researcher with interests in eco-evolutionary dynamics, persistence, and adaptation of
(meta)populations. Amaïa has expertise in life-history traits evolution and population dynamics, using a modelling approach to simulate population responses to environmental and anthropogenic changes (Lamarins et al., 2024, 2025a, b).
Hosting lab
Evolution, Conservation and Genomics; University of Helsinki; PI: Pr Craig Primmer
References
Cádiz M, López M, Díaz-Domínguez D, et al (2020) Whole genome re-sequencing reveals recent signatures of selection in three strains of farmed Nile Tilapia (Oreochromis niloticus). Sci Rep 10:1–14. https://doi.org/10.1038/s41598-020-68064-5
Cádiz MI, Sinclair-Waters M, Erkinaro J, et al (2025) Weak fine-scale genetic structure and considerable life-history diversity in a near-pristine subarctic Atlantic salmon (Salmo salar) river. Conservation Genetics 26:983–995. https://doi.org/10.1007/s10592-025-01717-y
Cádiz MI, Tengstedt ANB, Sørensen IH, et al (2024) Demographic History and Inbreeding in Two Declining Sea Duck Species Inferred From Whole-Genome Sequence Data. Evolutionary Applications 17:. https://doi.org/10.1111/eva.70008
Erkinaro J, Czorlich Y, Orell P, et al (2019) Life history variation across four decades in a diverse population complex of atlantic salmon in a large subarctic river. Canadian Journal of Fisheries and Aquatic Sciences 76:42–55. https://doi.org/10.1139/cjfas-2017-0343
Harvey A, Skaala Ø, Borgstrøm R, et al (2021) Time series covering up to four decades reveals major changes and drivers of marine growth and proportion of repeat spawners in an Atlantic salmon population. Ecol Evol 12:. https://doi.org/10.1002/ece3.8780
Lamarins A, Carlson SM, Prévost E, et al (2025a) Eco-Evolutionary Consequences of Selective Exploitation on Metapopulations Illustrated With Atlantic Salmon. Fish and Fisheries 26:291–305. https://doi.org/10.1111/faf.12881
Lamarins A, de Coligny F, Labonne J, et al (2025b) IBASAM: a spatially explicit demo-genetic individual-based model for anadromous salmonids (meta)populations. Individual-based Ecology 1:. https://doi.org/10.3897/ibe.1.153305
Lamarins A, Prévost E, Carlson SM, Buoro M (2024) The importance of network spatial structure as a driver of eco-evolutionary dynamics. Ecography 2024:.https://doi.org/10.1111/ecog.06933
Otero J, Jensen AJ, L’Abeé-Lund JH, et al (2012) Contemporary ocean warming and freshwater conditions are related to later sea age at maturity in Atlantic salmon spawning in Norwegian rivers. Ecol Evol 2:2192–2203. https://doi.org/10.1002/ece3.337
Vollset K, Urdal K, Utne K, et al (2022) Ecological regime shift in the Northeast Atlantic Ocean revealed from the unprecedented reduction in marine growth of Atlantic salmon. Sci Adv 8:2542
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