Contrasting Genomic Signatures of Local Adaptation in Lodgepole Pine (Pinus contorta) and Interior Spruce (Picea glauca x Picea engelmannii)

Understanding the genomic basis of local adaptation is a central question in evolutionary biology, with important applications to forestry management. Common garden studies in both lodgepole pine (Pinus contorta) and interior spruce (Picea glauca x Picea engelmannii) have shown considerable local adaptation, yet the genomic basis of this adaptation is poorly understood. Here, we use targeted resequencing of a large fraction of the exome to characterize the genomic basis of adaptation in hundreds of individuals of each species, sampled along wide geographical and climatic gradients. We use a combination of GWAS and environment association analyses to identify regions of the genome with signatures that are strongly consistent with local adaptation. By examining the proportion of regions with strong signatures that are shared between species, we can address the extent of parallelism and gene re-use.