Correlation networks of phenolics in hybridizing European <i>Populus</i> species.

<p>Metabolite correlation networks of 38 phenylpropanoids (for abbreviations see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128200#pone.0128200.t001" target="_blank">Table 1</a>) identified by UHPLC-QTOF-MS. Chlorogenic acids are coloured in white, salicinoids in grey and flavonoids in black. Correlation networks were obtained by applying Fruchterman-Reingold 2D algorithm on Spearman correlations (r>0.5, p<0.001). Metabolite correlation networks are presented for (a) admixed individuals from the Ticino river valley hybrid zone (n = 109), using thresholds of 0.05 < genomic admixture proportion Q < 0.95 to delimit admixed trees; (b) individuals of <i>P</i>. <i>alba</i> (n = 51), (c) individuals of <i>P</i>. <i>tremula</i> (n = 46) from natural hybrid zones.