Ancient vicariance is reinforced by adaptive divergence in the southern beech: Contributions from geogenomics

Abstract Aim Geogenomics seeks to understand geological processes linked lineage divergence. However, the mechanisms that conserve ancient signals in spite of gene flow are still unclear. In southern beech, deep divergence produced by vicariant events is associated with marine transgressions. We hereby evaluate hypothesis this maintained diversifying selection. Location Southern Argentina and Chile. Taxon Nothofagus dombeyi. Methods The means analysis molecular variance (AMOVA), principal coordinate analysis, assignment tests multiple matrix regression analyses were assessed using chloroplast DNA neutral outlier single nucleotide polymorphisms (SNPs). Several environmental variables used characterize potential within‐species niche structuring genotype–environment associations. Results Two deep‐rooted latitudinally structured lineages resulted from cpDNA, northern cluster being more genetically diverse than one. Of total 2943 SNPs, 33 identified as outliers two genetic clusters. Neutral SNPs yielded no structure AMOVA, whereas higher (>75%) F ST values obtained for cpDNA SNPs. Precipitation mostly population clusters suggested climatic niches, consisting cold dry south variable precipitation, temperature soil conditions north. Associations distance environment geography isolation‐by‐distance isolation‐by‐ecology or isolation‐by‐environment effects. Main conclusions Ancient N. dombeyi, originally driven vicariance, has been selection under distinct also define niches. Deeply rooted phylogeographical breaks can be conserved continuously distributed species absence current geographical barriers. Yet, physical gradients exert differential selective pressures, which face flow. As a result, lead geographically localized differentially adapted groups populations detected combination traditional novel genomic methods.