Tree Visualization

Large phylogenetic trees can be thought of as giant computational templates and used to map the sequence of events that led to the present-day observations -- for example, they can be used to estimate the timing of past gene or genome duplication events, to detect horizontal gene transfer, to correlate genomic changes with the emergence of evolutionary novelties, and to associate patterns of adaptation with geographic distribution, climatic change, or co-evolution. Moreover, the metaphor of the Tree of Life is well understood by the public at large and the availability of intuitive visualization tools that allow the free exploration of evolutionary data is critical to reach out to this broader audience.

The primary goal of the Tree Visualization working group is to develop an application for viewing, analyzing and exploring large phylogenetic trees. Because the need to visualize large phylogenetic trees is nearly ubiquitous across the different components of the iPToL project, the Tree Visualization Working Group is crosscutting in nature, integrating elements and needs from the other working groups.

The working group has developed a platform-independent, web-based viewer that enables users to rapidly navigate phylogenetic trees of up to a million taxa with a performance comparable to traditional desktop applications. The interface provides an overview of the whole phylogeny plus a detailed view where the user can pan and zoom on the tree detail, with clades collapsing and expanding automatically. The interface supports the annotation of nodes, branches and subtrees in order to associate a tree with other types of metadata. The application uses Google Web Toolkit (GWT) for the user interface and client/server communication, and is architected in a way that separates the core rendering capabilities and user interface into libraries, allowing integration of this viewer into other websites.