ORAL PRESENTATION: Genomic assessment of local adaptation in dwarf birch to inform a climate resilient assisted gene flow strategy

Submitted by : Fady Bruno
Abstract type : Oral presentation
Session type : Conference session 4: EVOLUTIONARY MANAGEMENT of FORESTS
Author Speaker : James S. Borrell

Information about other authors :

Jasmin Zohren, Richard A. Nichols, Richard R. A. Buggs

Abstract :

When populations are small, isolated and declining under climate change, some may become locally maladapted. Detecting this maladaptation could allow rapid interventions to conserve rare species or genetic diversity, even if based on incomplete knowledge. Population maladaptation may be estimated by finding genome‐environment associations (GEA) between allele frequencies and environmental variables across a local species range, and identifying populations whose allele frequencies do not fit with these trends. We could then design assisted gene flow strategies to adjust the allele frequencies of maladapted populations, requiring comparatively modest conservation interventions. Here, we investigate this strategy in Scottish populations of the montane plant dwarf birch (Betula nana). Using genome‐wide restriction site‐associated single nucleotide polymorphism (SNP) data we found 267 significant associations between SNP loci and environmental variables. Populations with a higher degree of maladaptation at putatively adaptive loci tended to be at the Southern range edge and have both reduced catkin production and seed germination rate. These loci were also significantly more commonly found within 10kb of a gene annotated on our reference genome, than non-candidate loci. In a complementary analysis, using environmental niche modelling (ENM) to evaluate the impact of climate change, we found annual mean temperature (35%), and mean diurnal range (15%), to be important predictors of the dwarf birch distribution. Intriguingly, we found a significant correlation between the number of loci associated with each environmental variable in the GEA, and the importance of that variable in the ENM. Together, these results suggest that the same environmental variables determine both adaptive genetic variation and species range in Scottish dwarf birch. We conclude by illustrating a theoretical assisted gene flow strategy that aims to maximize the local adaptation of dwarf birch populations under climate change by matching allele frequencies to current or future environments.

Bibliografic references :

Borrell, J. S., Zohren, J. , Nichols, R. A. and Buggs, R. J. (2019), Genomic assessment of local adaptation in dwarf birch to inform assisted gene flow. Evol Appl. doi:10.1111/eva.12883

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Keywords : assisted gene flow, environmental niche modelling, genome-environment associations, local adaptation