Patterns of neutral and adaptive genetic diversity across the natural range of sugar pine (Pinus lambertiana Dougl.)
Demographic and environmental forces shape geographical patterns of genetic diversity. Knowledge thereof is not only important for evolutionary ecologists but, in light of future climate change, will be of interest to conservation biologists as well. Sugar pine (Pinus lambertiana Dougl.) is an ecologically important species found in mixed conifer forests across western North America. We applied a candidate-gene-based environmental study to infer spatial patterns in neutral genetic variation and to identify genetic variants associated with local adaptation to drought. Using a panel of 186 candidate gene single nucleotide polymorphisms (SNP), we genotyped 313 individual trees sampled across the entire state of California, USA. We found evidence for a large-scale subdivision into two genetic clusters along the latitudinal axis and increased genetic similarity among sugar pines within a 200–300-km boundary. Associating allelic to environmental variation indicated nine putative SNPs related to local adaptation to drought. These results provide insights into neutral population structure across the natural range of sugar pine and further substantiated a key role of the mitochondrial import inner membrane machinery in enhanced tolerance to drought and constitute important steps into unravelling the eco-evolutionary dynamics in sugar pine.
KeywordsSugar pine Pinus lambertiana Dougl. Drought tolerance Adaptation Candidate-gene based environmental study
We are very much indebted to J. Liechty for his bioinformatical assistance. We wish to express our gratitude to J. Gleason and J. Dunlap from the US Forest Service for all the logistic support when collecting seed samples at Placerville, CA, USA, and providing all the necessary metadata. A postdoctoral fellowship from the Belgian American Educational Foundation (BAEF) and a travel grant from the Research Foundation–Flanders (FWO) was granted to CV.
Data archiving statement
Genotype and environmental data have been deposited in the TreeGenes Database (accession number TGDR059).
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