This visualisation provides a simple graphical representation of
the distribution of this family across species. You can find the
original interactive tree in the
adjacent tab.
More...
This chart is a modified "sunburst" visualisation of
the species tree for this family. It shows each node in the
tree as a separate arc, arranged radially with the superkingdoms
at the centre and the species arrayed around the outermost
ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each
sequence that has a match to this family. For each node in the
resulting tree, we draw an arc in the sunburst. The radius of
the arc, its distance from the root node at the centre of the
sunburst, shows the taxonomic level ("superkingdom",
"kingdom", etc). The length of the arc represents
either the number of sequences represented at a given level, or
the number of species that are found beneath the node in the
tree. The weighting scheme can be changed using the sunburst
controls.
In order to reduce the complexity of the representation, we
reduce the number of taxonomic levels that we show. We consider
only the following eight major taxonomic levels:
- superkingdom
- kingdom
- phylum
- class
- order
- family
- genus
- species
Colouring and labels
Segments of the tree are coloured approximately according to
their superkingdom. For example, archeal branches are coloured
with shades of orange, eukaryotes in shades of purple, etc. The
colour assignments are shown under the sunburst controls. Where
space allows, the name of the taxonomic level will be written on
the arc itself.
As you move your mouse across the sunburst, the current node
will be highlighted. In the top section of the controls panel we
show a summary of the lineage of the currently highlighed node.
If you pause over an arc, a tooltip will be shown, giving the
name of the taxonomic level in the title and a summary of the
number of sequences and species below that node in the tree.
Anomalies in the taxonomy tree
There are some situations that the sunburst tree cannot easily
handle and for which we have work-arounds in place.
Missing taxonomic levels
Some species in the taxonomic tree may not have one or more of
the main eight levels that we display. For example, Bos
taurus is not assigned an order in the NCBI taxonomic tree.
In such cases we mark the omitted level with, for example,
"No order", in both the tooltip and the lineage
summary.
Unmapped species names
The tree is built by looking at each sequence in the full
alignment for the family. We take the name of the species given
by UniProt and try to map that to the full taxonomic tree from
NCBI. In some cases, the name chosen by UniProt does not map to
any node in the NCBI tree, perhaps because the chosen name is
listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst
tree, we group them together in a separate branch (or segment of
the sunburst tree). Since we cannot determine the lineage for
these unmapped species, we show all levels between the
superkingdom and the species as "uncategorised".
Sub-species
Since we reduce the species tree to only the eight main
taxonomic levels, sequences that are mapped to the sub-species
level in the tree would not normally be shown. Rather than leave
out these species, we map them instead to their parent species.
So, for example, for sequences belonging to one of the
Vibrio cholerae sub-species in the NCBI taxonomy, we
show them instead as belonging to the species Vibrio
cholerae.
Too many species/sequences
For large species trees, you may see blank regions in the outer
layers of the sunburst. These occur when there are large numbers
of arcs to be drawn in a small space. If an arc is less than
approximately one pixel wide, it will not be drawn and the space
will be left blank. You may still be able to get some
information about the species in that region by moving your mouse
across the area, but since each arc will be very small, it will
be difficult to accurately locate a particular species.