Genome-wide scans reveal cryptic population structure in a dry-adapted eucalypt

Genome-wide DArTseq scans of 268 individuals of Eucalyptus salubris, distributed along an aridity gradient in southwestern Australia, revealed cryptic population structure that appears to signal hitherto unappreciated ecotypic differentiation and barriers to gene flow. Genome-wide scans were undertaken on 30 wild-sampled individuals from each of nine populations; 10 individuals per population were measured for habit and functional traits. DArTseq generated 16,122 high-quality markers, of which 56.3 % located to E. grandis chromosomes. Genetic affinities of the nine populations were only weakly correlated with geographic distances. Rather, populations appeared to form two distinct molecular lineages that maintained their distinctiveness in an area of geographic overlap. Twenty-four outlier markers signalled divergent selection and differentiation of the two putative lineages. Populations from the two lineages were phenotypically differentiated in leaf thickness, specific leaf area (SLA) ...