Figure 4

Midpoint rooted, bootstrapped trees based on the eight genes analysed by direct sequencing (and the genotypes where most of the sequences were present) generated using maximum likelihood in PhyML with HKY85+ G substitution model. Asterisks indicate nodes with 50% or higher bootstrap support. The three Salix subgenera (according to most authorities) are indicated. Trees are shown with the P. trichocarpa gene model and P. tremula sequences included (Figure 4A) or excluded (Figure 4B).