Wikispecies currently has around 350,000 articles, each corresponding to a taxonomical grouping (a taxon).  That’s a huge amount of information about where organisms lie on the tree of life.  However if you don’t recognize the scientific names of the groups you’re looking at, it can be difficult to find your way around or get a clear sense of how it all fits together.

I’ve tried to make exploring the Wikispecies data more intuitive by rendering it in an illustrated tree format.  The thumbnails above are a few points of entry into that tree.  Once you’re in, click to navigate, and use the mouse wheel to zoom (needs Javascript, and may not work in IE).

Can’t find your favorite species?  Try searching by common name on this list.


In case you’re interested in the technical details...

The graphs were laid out automatically using Graphviz.  A graph contains at most 170 nodes.  How do we decide which 170 to display?  Every node in the tree of life is assigned an importance.  A node is important to the degree that it (a) contains a lot of material down the tree, and (b) came from something important up the tree.  The nodes you see in a graph are the maximally important elements of that sub-tree.

Edge color shifts randomly as we descend from the root of each graph, and slows as the nodes reached decrease in importance.  Ideally, this gives visual cues to clustering at different levels of structure.  See Epidendroideae for a particularly good example of how color can bring out the hierarchical structure.

Getting a workable tree structure out of Wikispecies wasn’t trivial.  Mother-daughter relations aren’t coded in a consistent way, so loops and other kinds of multiple dominance are unavoidable.  I extracted a proper tree by pruning both loops (links to a higher containing node) as well as other duplicate mothers (retaining only the link to the deepest mother).  This last decision was somewhat arbitrary, so the result is just one of many ways of treeing the Wikispecies structure.

Since the goal was to get something that looks nice, I also pruned leaves that lacked an illustration on Wikispecies.  This means that only around 10% of the entries are visible here, and some sub-trees (e.g. Tyrannosauroidea) can’t be reached by clicking down from the root.  Note though that imageless entries do still contribute to the importance calculation; thus, content high up in the tree isn’t skewed towards photogenic material. 

If you’re interested in using the raw tree data, you can download it here.  If you have any comments, questions, or suggestions, please let me know.