The fact that all life on Earth is connected through common ancestry in a single tree-like structure has fascinated biologists for over one and a half century and has become a central theme in biological sciences. Up to this point, the scientific community has made substantial advances in reconstructing the shape of this Tree of Life, especially in the last two decades with the advent of DNA sequences. But despite the current knowledge on a great portion of evolutionary relationships among organisms, two main limitations stand in front of the goal of displaying a fully resolved tree of life to the public: 1) Information about evolutionary relationships of groups of organisms are widely scattered into thousands of scientific papers, and 2) Effective ways to visualize a very large tree of life with thousands of leaves are currently lacking, so a diagram of such dimension is hardly contemplable within a printed page of a book or a scientific journal, and even digital tools are lagging behind (but see this web app) . Although several efforts have been made to tackle the aforementioned limitations, there is none that has focused on overcoming both simultaneously (be sure to read one of the upcoming blog entries in which pre-existing projects aiming to build the tree of life are summarized and how this project differs from them).
The Tree of Life App project aims to overcome both limitations by offering a tool to explore family-level evolutionary relationships among organisms in an interactive way in the form of a mobile app currently available for iPhones (click here to download the lite version of the app). The evolutionary tree displayed in the app is the result of an assemblage of hundreds of phylogenetic studies published in peer reviewed journals. It can be explored in a similar way to Google Maps/Earth: by taking advantage of the touch screen, users can zoom in or out using the pinch gesture and have a more detailed view of evolutionary relationships at any desired part of the tree.
The starting tree does not seem to be very large, because most of the main groups of organism (Bacteria, Plants, Vertebrates, etc) are shown as collapsed branches. However, users may tap on the pictures of such branches to open them and display all of their contents- The lite version of the App, which is totally free, enables users to open the immense vertebrate tree with over 2000 taxonomic families, as well as other small groups of organism such as cryptophytes, centroheliozoans and chaetognaths, to name a few of them.
For those with further interest in other groups of organisms that are locked in the lite version, Tree of Life Pro is the way to go (available here). In this full version, users not only have access to groups like bacteria, amoebae, sponges and tardigrades among others, but they will also have access to explore groups that are currently absent but will be made available soon in the upcoming updates, such as plants, fungi or insects.
In the following video, most of the functionalities of the app are displayed, including the search function, the ability to highlight clades, collapse branches, view subtrees, and determining divergence times and extinction dates.
Be sure to keep checking back this blog to find out how the tree was built, how are fossil taxa incorporated in the mainly molecular-inferred phylogenetic tree, how it is constantly updated, and how it differs from similar Tree of Life projects.
Posted by Andrés Del Risco