FIG 5.

Maximum-likelihood phylogenetic tree of gammaretroviruses inferred using complete env nucleotide sequences, excluding GALV GenBank sequences. GALV GenBank sequences were excluded to avoid any influence of possible errors in these sequences on the analysis of selection. Node robustness was assessed with 500 rapid bootstrap pseudoreplicates. Numbers above or below the internode branches indicate bootstrap support. The GALV strain sequences generated in this study are highlighted in blue. Branches with significant (P < 0.05) evidence of episodic diversifying selection as indicated by the BSREL method are marked with an asterisk. GenBank accession codes are shown in brackets. The scale bar indicates 0.2 nucleotide substitutions per site. The tree is midpoint-rooted for purposes of clarity. All abbreviations can be found in Table 2.