Adaptation, migration or extirpation: climate change outcomes for tree populations

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Species distribution models predict major tree range shifts due to climate change.
• Observed migration rates are insufficient to track projected climate velocities.
• Adaptation potential depends on genetic variation, selection, and biotic interactions.

Purpose of the Study:

• To assess the adaptive capacity of tree populations facing climate change.
• To identify factors influencing species' ability to track suitable climates.
• To inform conservation strategies, including assisted migration.

Main Methods:

• Analysis of phenotypic clines in temperate and boreal trees along temperature gradients.
• Evaluation of genetic architecture (many small-effect genes) and its role in adaptation.
• Consideration of factors like gene flow, fecundity, and interspecific competition.

Main Results:

• Temperate and boreal trees exhibit local adaptation to temperature gradients.
• High fecundity and polygenic traits may facilitate rapid local adaptation.
• Widespread, high-fecundity species are likely to adapt but may experience lag.
• Rear-edge populations and vulnerable species face extirpation risk.

Conclusions:

• Local adaptation and genetic redundancy can promote tree persistence.
• Adaptational lag is expected, potentially weakening interspecific competition.
• Facilitated migration is a viable conservation strategy for vulnerable tree species.
• Species with small populations or disease susceptibility are candidates for assisted migration.