  Phylogenetic trees are a central tool in understanding evolution. They are
typically inferred from sequence data, and capture evolutionary relationships
through time. It is essential to be able to compare trees from different data
sources (e.g. several genes from the same organisms) and different inference
methods. We propose a new metric for robust, quantitative comparison of rooted,
labeled trees. It enables clear visualizations of tree space, gives meaningful
comparisons between trees, and can detect distinct islands of tree topologies
in posterior distributions of trees. This makes it possible to select
well-supported summary trees. We demonstrate our approach on Dengue fever
phylogenies.
