Genetic bases of leaf and reproductive phenology in European beech (Fagus sylvatica) and sessile oak (Quercus petraea) and their role in adaptation

Growth and reproduction are two key processes that drive the long-term success in adaptation in trees. Unlike annual plants, trees undergo multiple reproductive cycles and have continuous growth, and therefore they way resources are allocated to growth and reproduction yearly, in response to variations in environmental conditions both in space and in time, drive long-term fitness in an integrated way.

Multiple international initiatives focus on the ecological drivers of inter-annual variations in reproductive activity in species like oak and beech, showing alternation of years with abundant and scarce seed output (a phenomenon called masting). Similarly, a rich literature—including robust modelling—focuses on the climatic determinants of leaf phenology.

Wild tree populations harbour vast amounts of phenotypic and genetic diversity, that are maintained over generations by a variety of processes and properties, including intense gene flow, large (effective) population sizes, and local (microgeographic) adaptation.

The extent of the genetic control of variations in growth and reproductive phenology is still largely unknown; how such genetically controlled variation contributes to adaptation to local conditions is also undiscovered. In addition to this, ongoing climate change represents a further selective factor that may shape the distribution and amount of genetic diversity at adaptive traits.

Unveiling such processes requires determining the genetic architecture of traits, predicting the phenotypes of individual trees based on their genotypes at regions driving phenotypic variation, and finally modelling the effect of selection on the evolutionary fate of populations.

To do this, the candidate will (i) contribute to the environmental and phenotypic characterisation of wild oak and beech stands; (ii) collect and analyse full-sequencing genetic data using Genome-Wide Association Study approaches; (iii) predict breeding values using BLUP, while taking into account environmental factors; (iv) use forward simulation approaches to predict the evolution of populations under climate change.

The PhD programme will be part of a larger research programme carried out by a multi-lab consortium including tree ecologists, evolutionary biologists, and modellers, and will be supported by funding from the REGEMAST (and partly FAGRESCUE) research grants.

The candidate will be based at INRAE Avignon (France) and will be registered as a student at Aix-Marseille University (“AMU”).

Applications should be submitted to Ivan Scotti (ivan.scotti[at]inrae.fr) and / or Julie Gaüzère (julie.gauzere[at]inrae.fr) on 2^nd July 2025 at the latest (prefer earlier submissions to allow us ot carry out interviews by 4 July).

For further information on the team, please visit the lab’s website, and in particular the team’s website.