Extending Taxonomic Visualisations

1. Extending Taxonomic Visualisations Dealing with Large Datasets, Structural Markers and Synonymy

2. Large Datasets • Layout • Datasets too large to display them in their entirety (in comparison to prev. work) • Only layout partial trees • Top-down layout from current node of interest (anchor node) • Stop drilling down into branch when size of nodes below a threshold • Various hierarchies displayed from top to bottom • Can be opened/closed • Nodes as rectangles • Node colored in top half if has been selected • Summary of user-selected descendants in lower half of node as bar chart • Size of node n by log(size(n))

3. Large Datasets • Brushing, Navigation and Selection • Left-click re-roots tree at anchor node • Right-click selects subtree rooted at clicked node in all hierarchies (via naming and/or synonymy) • Optionally re-rooting at clicked node • Least common ancestor if clicked node not found in other hierarchies • Brushing temporarily on hover in same fashion as right-click select • Tooltip on hover LCA select

4. Large Datasets • Brushing, Navigation and Selection • Left-click re-roots tree at anchor node • Right-click selects subtree rooted at clicked node in all hierarchies (via naming and/or synonymy) • Optionally re-rooting at clicked node • Least common ancestor if clicked node not found in other hierarchies • Brushing temporarily on hover in same fashion as right-click select • Tooltip on hover • Text size, Focus & Context influence node size • Focus & Context ratio determines proportion of space allocated for selected and not selected nodes

5. Large Datasets • Brushing, Navigation and Selection • Left-click re-roots tree at anchor node • Right-click selects subtree rooted at clicked node in all hierarchies (via naming and/or synonymy) • Optionally re-rooting at clicked node • Least common ancestor if clicked node not found in other hierarchies • Brushing temporarily on hover in same fashion as right-click select • Tooltip on hover • Text size, Focus & Context influence node size • Focus & Context ratio determines proportion of space allocated for selected and not selected nodes • Order in sibling groups may be changed • Alphabetically, by rank, by number of child taxa,… • Can help determine size distributions • Can help to find the highest rank within a group of child nodes

6. Structural Markers • Finding differences between tree revisions can be computationally expensive • Depending on the actual type of change made • Whether exact locations are to be obtained • Visualization requires cheap computation for large datasets • Algorithm checks • Whether selected nodes keep same parent in other hiearchies compared to original hierarchy. • Node is flagged as having had a change and consequently all ancestors up to root node • Flagged nodes are indicated in tree visualization • Hatched: Parent has changed between tree • Stripped: descendent set contains hatched node

7. Synonymy

8. Possible Future Work • Comparison of trees at multiple resolutions dependent on sub-tree size • User could benefit from more information on structure change given by more computationally expensive algorithm used on a smaller set of nudes (subtree) • Are users happy with this type of tree visualization? • Any tasks users want to perform on the trees that are not covered? • Synonymy can be given by expert articulations of Euler

9. Use Case: IT IS Dataset and Structural Markers • 7 Taxonomy Revisions of dataset with each 180.00 – 250.000 taxa • Tasks • Observe whether growth occurred between revisions and where growth is concentrated • If taxa moved between revisions: • Did taxa’s siblings move in the same parent? • New parent otherwise unchanged? • New parent newly formed?

10. Use Case: IT IS Dataset and Structural Markers

11. Use Case: IT IS Dataset and Structural Markers • More problematic to discover a taxon that has undergone a purely internal revision.