Figure 3
From: Molecular evolution of synonymous codon usage in Populus
Unrooted tree representing the phylogenetic relationship between the five species. ML estimates of non-synonymous (d N ) and synonymous (d S ) substitution rates, d N /d S ratios (in parentheses) and the maximum likelihood estimates of selection acting on preferred codons (4N e s) are shown above each branch and are calculated from the concatenated data set of 158 genes. See text for further details. Branch lengths are proportional to synonymous substitution rates. All branches have 100% bootstrap support.