Using the Phylogenetic Tree Glyph

Note: the phylogenetic tree display appears to be broken in GBrowse version 2.0. Help bringing it back would be much appreciated.

This mini-tutorial section will guide you through the Phylogenetic Tree Viewer. It is a track that will draw a cladogram of species that have alignments with the species within the set view window. The alignment scores will be drawn at far magnification, and the DNA alignments for close magnification. This tutorial is based on the Volvox database created within the main GBrowse2 tutorial.

There are three main types of data required for this view: the GFF alignment data, alignment sequence data, and the species tree file.

The tree file is read with the use Bio::TreeIO module and all formats compatible with this can be used with this track. Note that all species do not have to be included in this file. All organisims not included in this file but included in the GFF alignment data will appear as disconnected branches in the cladogram (Figure AAA and AAB). Here is an example using the NEWICK format:

Different formats can be specified by changing the 'tree_format' entry in this track's conf file entry.

The alignment and gap data makes use of the GFF3 CIGAR format as specified by the sequence ontology website: Alignments are specified with the standard start, stop and score columns and can contain special tag=value pairs. Specifically 'species' indicate the name of the species, 'Target' indicate which FASTA sequence to use and the 'Gap' indicates matches and mismatches. Matches are specified by 'M', deletions by 'D' and insertions by 'I' followed by the number of bases. An example can be found in the volvox_phyloalign.gff3 file. Copy this file into your data_files folder.

ctgA    pa      submatch        1050    1500    8.5e-28 +       .       ID=Match3;species=mouse;Target=pagt2215 1 451;Gap=M70 D2 M2 I2 M2 D17 M33 I20 M5 D3 M317
ctgA    pa      submatch        7000    7300    9.5e-36 +       .       ID=Match3;species=mouse;Target=pagt2215 953 1253;Gap=M301
ctgA    pa      match   1150    7200    .       +       .       ID=Match5;species=rabbit;Target=pagt7675 1 1153
ctgA    pa      submatch        1150    1500    4.1e-43 +       .       ID=Match5;species=rabbit;Target=pagt7675 1 351;Gap=M7 D2 M2 I2 M342

The FASTA sequence files are added just as all the other tracks. Be sure that your 'Target' column specify the correct FASTA species to use. The conf file is a bit bloated for now. Make sure you specify the exact path of your tree file and what format it is in. conf file example

glyph         = phylo_align
global feature = 1
height       = 40
draw_clado_left = 0
species_spacing = 1.2
species_spacing_score = 5
hide_label = 0
fgcolor      = darkblue
errcolor     = red
axis_color   = darkorange
mid_axis_color = yellow
clado_bg     = peachpuff
bg_color     = white
targ_color   = yellowgreen
ref_color    = palegoldenrod
key          = Phylogenetic Alignment
reference_species    = volvox
#tree_step_width = 5
tree_file    = /var/www/gbrowse2/databases/volvox/species.tre
tree_format  = newick

If everything is running correctly, you should see the images shown in Figures AAA and AAB, depending on the zoom level.

Figure AAA: Phylogenetic alignments scoring level. Note that as 'dog' is not included in the original tree file, it will be placed as a disconnected member of the cladogram.

Figure AAB: Phylogenetic alignments at the DNA level. Note that as 'dog' is not included in the original tree file, it will be placed as a disconnected member of the cladogram.

Lincoln D. Stein,
Cold Spring Harbor Laboratory
Last modified: Tue Jan 26 18:01:15 EST 2010