Assembling an illustrated family-level tree of life for exploration in mobile devices

Since the concept of the tree of life was introduced about 150 years ago, a considerable fraction of the scientific community has focused its efforts on its reconstruction, with remarkable progress during the last two decades with the advent of DNA sequences. However, the assemblage of a comprehensive and explorable tree of life has been a difficult task to achieve due to two main obstacles: (i) information is scattered into several individual sources and (ii) practical visualization tools for exploring large trees are needed. To overcome both challenges, we aimed to synthesize a family-level tree of life by compiling over 1400 published phylogenetic studies, choosing the source trees that represent the best phylogenetic hypotheses to date based on a set of objective criteria. Moreover, we dated the tree by employing over 550 secondary calibrations using publicly available sequences for more than 5000 taxa and by incorporating age ranges from the fossil record for over 2800 taxa. Additionally, we developed a mobile app for smartphones to facilitate the visualization and exploration of the resulting tree. Interactive features include exploration by the zooming and panning gestures of touch screens, collapsing branches, visualizing specific clades as subtrees, a search engine, and a timescale to determine extinction and divergence dates, among others. Small illustrations of organisms are displayed at the terminals to better visualize the morphological diversity of life. Our assembled tree currently includes over 7000 families, and its content will be expanded through regular updates to cover all life on earth at the family level. Despite the abundance of phylogenetic studies published in the scientific literature, exploring a comprehensively assembled tree of life has been hampered by the overly scattered nature of information and the scarcity of visualization tools for large trees. Here, we synthetized a family-level tree of life with almost 7500 terminals by compiling over 1400 phylogenetic studies, which was time-calibrated by using DNA sequences and data from the fossil records for thousands of taxa, and by employing hundreds of secondary calibrations. We also developed a mobile app for smartphones to interactively explore the resulting tree, which includes time-proportional branch lengths and small illustrations of the represented organisms at the terminals. With this, we provide a useful, publicly available tool for exploring the interrelationships of the vast diversity of life on earth. image