Zooming down the tree of life, digitally

Exploring the evolutionary tree of life is now as easy as navigating an online map, thanks to a new interactive website called OneZoom, which went live on 16 October.

Since Darwin, biologists have struggled to draw a tree showing important details about the many known living organisms and how they are related to one another. Even relatively simple trees have been extremely challenging to visualise without huge sheets of paper or multiple computer screens.

Now OneZoom, which was partly inspired by the zooming technology of mapping software such as Google Maps, makes it possible to start with a broad view of life on Earth, then zoom in on any point to explore incrementally smaller categories of life, using intuitive mouse actions.

Dr James Rosindell, from the Department of Life Sciences at Imperial College London, conceptualised and programmed OneZoom in collaboration with Dr Luke Harmon, from the Department of Biological Sciences at the University of Idaho.

“OneZoom gives you a natural way to explore large amounts of complex information like the tree of life,” explained Dr Rosindell. “It’s intuitive because it’s similar to the way we explore the real world; by moving towards interesting objects to see them in more detail.”

The traditional tree of life is generally drawn starting with a thick trunk that represents the first life on earth. The trunk then splits into large boughs for different categories of life such as plants and animals, then ever smaller branches for groups such as insects, fish, birds and mammals.

The amount of information the tree can show is usually constrained by the size of the paper it’s viewed on, but Dr Rosindell saw a way to overcome this problem, taking advantage of the unlimited space in the digital world.

“We’re still looking at data on the screen in ways that can easily be printed on paper and that’s a serious visual constraint. In fact, it’s no longer necessary to restrict ourselves in this way because we now mostly view the information on a screen only. OneZoom embraces this by laying out the data in an exciting, interactive way that could not be captured on printed sheets,” he said.

OneZoom looks initially like a tree, with trunk, branches and twigs, and each species represented by a coloured leaf. As you travel along the trunk towards the first branches, it’s easy to zoom in and out, pan around and explore the evolutionary links between different species of organism, as though they were roads on a map. By zooming in on each subgroup of organisms, more details are revealed, such as the degree to which their members are threatened with extinction, links to more information and soon, photographs.

Currently, the OneZoom site only features the tree of mammals, including over 5000 species that are arranged in closely related groups and colour-coded to indicate their risk of extinction according to the internationally recognised IUCN Red List. Dr Rosindell aims to complete the next stages of the project over the coming years. This will involve refining the content of OneZoom and growing its scope as more data becomes available from international research projects, such as the Open Tree of Life Project.

“After decades of study, scientists are probably only a year away from having a first draft of the complete tree of life. It would be a great shame if having built it we had no way to visualise it,” Dr Rosindell continued.

Dr Rosindell hopes that OneZoom will be used by scientists to help uncover new patterns in nature, to teach people about the evolution and diversity of life, and to help make attractive and engaging displays for venues such as zoos and museums.

Professor Joel Cracraft, Curator in charge of birds at the American Museum of Natural History in New York, added: “This will revolutionise how we teach and understand the Tree of Life. It is an invaluable tool for communicating the grand scope of life’s history to children as well as adults.”

“The problem of visualising an evolutionary tree for millions of species is a challenging one. OneZoom provides a creative solution that will be of great utility, especially for web-based representations of the tree of life,” said evolutionary biologist Professor David Hillis, at the University of Texas at Austin in the USA.