Understanding the origin of adaptive genetic variation and its role for the vulnerability of beech forests to climate change

Maladaptation due to rapid climate change is one of the greatest threats to biodiversity and ecosystem functioning. Climate variation is also a major driver of local adaptation and of phenotypic and genetic variation within species. Although local adaptation is common in nature (Hereford 2009) and most quantitative traits (e.g., growth, morphology) show substantial genetic variation within populations (Mousseau & Roff 1987), we still do not know how such pre-existing genetic diversity will contribute to species’ adaptation to climate change. Addressing this question in long-lived species, such as forest trees, is particularly critical as their temporal adaptation will largely rely on standing genetic variation, while the appearance of new mutations will only play a minor role over short timescales.

Our working hypothesis is that gene flow and spatially varying selection –through environmental heterogeneity – are key drivers of within-population genetic diversity and that such diversity will enhance the adaptation of forest populations by facilitating the exchange of alleles favorable to future climates. This expectation is itself based on a non-equilibrium hypothesis, which considers that locally adapted populations are progressively disrupted by rapid environmental changes. While forest managers are in demand of solutions to improve forests resilience, the opportunities offered by natural and assisted gene flows between spatially structured populations are still undervalued.

The main goal of ADAPTBEECH is to further our understanding of the origin of adaptive genetic diversity and to model its consequences for species persistence under climate change. It will focus on common beech, a dominant tree species of Central Europe’s natural forests.