Data from: 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) and leaf nitrogen per unit mass (Nmass). The more
northerly lineage (with thinner leaves) occurred in hotter, drier
conditions with higher radiation. Populations of the more southerly
lineage occurred on soils that were relatively low in phosphorus; the
trees had thicker leaves, lower SLA and lower leaf Nmass, consistent with
general responses to low nutrient levels. While historic isolation and
drift may have contributed to the cryptic population structure observed,
there is evidence of ecotypic adaptation, which may provide an exogenous
barrier to gene flow. This study highlights the power of new molecular
technologies to provide novel insights into the genetic architecture of
wild populations.