Contexte du recrutement et définition de poste :

2 stages de Master sur l'éco-évolution du Saumon de l'Atlantique en Europe - Evolution, conservation et génomique. Université d'Helsinki

Contexte : Les populations de saumon atlantique (Salmo salar) à l’échelle mondiale ont connu un déclin ou ont déjà disparu (ICES 2025), principalement en raison de pressions anthropiques au cours des deux derniers siècles. Parallèlement à ces baisses démographiques, les programmes de suivi à long terme ont signalé des changements phénotypiques rapides, notamment des variations de l’âge de maturité et de la croissance à travers leur répartition dans l’Atlantique Nord (Otero et al., 2012 ; Erkinaro et al., 2019 ; Harvey et al., 2021 ; Vollset et al., 2022). Des modifications génétiques ont également été documentées, dont une homogénéisation croissante entre les populations (Ostergren et al., 2021). Étant donné que ces caractères phénotypiques et génotypiques influencent la condition physique du saumon et la résilience des populations, il est essentiel de comprendre leurs dynamiques temporelles. Les populations européennes bénéficient de programmes de suivi à long terme, offrant une occasion unique d’étudier les tendances temporelles de vie et de diversité génétique sur une large échelle géographique et le long d’un gradient environnemental.

À l’aide de ces jeux de données, nous proposons deux projets de mémoire de master :

Two Master’s thesis topics on Atlantic salmon eco-evolutionary change across Europe - Evolution, Conservation and Genomics; 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.

Encadrants / Supervisors

Dr. María Cádiz Escobar (maria.cadiz-escobar@helsinki.fi):

Chercheuse postdoctorale spécialisée en génétique des populations, génomique, évolution, conservation et bioinformatique (Cádiz et al., 2020, 2024, 2025). Maria mène actuellement des études sur la génétique des populations et l’évolution des gènes à fort effet liés aux stratégies vitales, en s’appuyant sur des séries chronologiques à long terme des populations européennes de saumon atlantique.

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):

Chercheuse postdoctorale spécialisée en dynamique éco‑évolutionnaire, persistance et adaptation des (méta)populations. Amaïa possède une expertise dans l’évolution des caractères vitaux et la dynamique des populations, en recourant à une approche de modélisation pour simuler les réponses des populations aux changements environnementaux et anthropiques (Lamarins et al., 2024, 2025a, b).

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).

Labo d'accueil et détail du stage / Hosting lab and internship details

Evolution, Conservation and Genomics; University of Helsinki Finland; PI: Pr Craig Primmer

Stage de 4 à 6 mois, sous convention mais non payé.

Internship of 4-6 months, conventionned but not paid.

Candidature /Application

• Envoyer /Send CV + motivation letter to : amaia.lamarins@helsinki.fi and maria.cadiz-escobar@helsinki.fi 

• Date limite / Deadline : 30 janvier / January 30

Bibliographie / 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

Profil recherché :

Profil attendu

Bac+3, Master 1 ou 2 en écologie de l'évolution avec intérêt en environnement aquatique et analyse de données.

Compétences demandées en analyse de données et utilisation de R 

Expected student profile

Bac +3 - Master student (1 or 2) in ecology and evolution, with interests in aquatic environments and data analysis

Skills in data analysis and R software are required