Tree of Life for 2.3 million species

Researchers present first version of a comprehensive family tree of all kinds

Pedigree of life - what it really looks like, researchers are only now putting it together © Zernliew / thinkstock
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Researchers have for the first time compiled a family tree of life for around 2.3 million known species. They combined tens of thousands of individual pedigree branches to a large overview of the relationships of animals, plants, fungi and microbes. Still, this first draft of an overall pedigree not only shows what we already know, it also reveals many still "dark", under-researched parts and also some discrepancies, the researchers report.

Pedigrees and phylogenetic studies for individual animal groups such as birds, plants or microbes are already abundant. After all, some include more than 100, 000 individual species and their relationships. But as detailed as these extracts from the tree of life were, the overall picture remained so unified and confusing.

2.3 million branch tips

In a project lasting more than three years, scientists from eleven research institutions joined forces to finally create a family tree of the big picture. For this they sighted thousands of digitally available single tree branches, and finally put together nearly 500 of them to the first tentative version of the Tree of Life.

"This is the first real attempt to connect the dots and put everything together, " explains Project Manager Karen Cranston from Duke University. "You could call it version 1.0. The resulting total tree has about 2.3 million branch tips - representing the phylogenetic relationships of as many species living today.

This is what the new tree of life looks like - it is clear that many areas are still patchy ©

Many gaps and discrepancies

However, the new tree of life is still a long way from being complete, as the researchers emphasize. Thus, some branches of the large pedigree, especially in the insects, fungi and microbes, are quite poorly stocked - the researchers call them the "dark parts of the tree". Other branches differ from common phylogeny or show contradictory interpretations. display

So far, for example, is controversial whether the archaea form their own, monophyletic group and thus the third great kingdom of life or whether they belong together with the nucleus-carrying eukaryotes in a large branch. Even when it comes to the question of exactly when the animals separated from the other groups or exactly where the origin of the eukaryotes lies, so far there is no clear answer and this is visible in such a total tree.

Gene data is only five-five percent of all species

"As important as it is to present the current state of knowledge, this first tree of life is also important to unveil what we do not yet know, " says co-author Douglas Soltis of the University of Florida. So far, many species lack genetic data that would facilitate their classification in the genealogical tree of life. Even the large databases of gene sequences so far contain less than five percent of all living things that exist on our planet.

Other data is available, but not online. As a result, the researchers in this first version could only consider about one in six phylogenetic studies. "There's a pretty big gap between what scientists know about living organisms and their relationships, and what's digitally available, " explains Cranston.

The aim is to help a newly developed software, the researchers from around the world, the editing of the pedigree on the basis of new data easier similar to a kind of Wikipedia for pedigree data.

"It's critically important to share data from previously published and future work so we can improve and complete the pedigree, " says Cranston.

Practical benefits

Because the knowledge about the family tree of life is not only an important contribution to get to know our planet and the history of its inhabitants better. "This summary tree will drive fundamental research into the nature of biodiversity and, ultimately, this will also promote applications in comparative biology, ecology, species conservation, agriculture and genomics, the researchers said.

And the tree of life also has tangible practical advantages, as the scientists emphasize. Understanding how millions of species are related to each other can help to find new remedies, improve crops, or trace the origins of infectious diseases such as AIDS, Ebola, or the flu.

(Duke University, 21.09.2015 - NPO)