Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Untangling the Tree of Life

16.05.2013
These days, phylogeneticists – experts who painstakingly map the complex branches of the tree of life – suffer from an embarrassment of riches.

The genomics revolution has given them mountains of DNA data that they can sift through to reconstruct the evolutionary history that connects all living beings. But the unprecedented quantity has also caused a serious problem: The trees produced by a number of well-supported studies have come to contradictory conclusions.


Antonis Rokas, Vanderbilt University

Two major phylogenetic studies recently reached contradictory conclusions about whether the snail’s closest relative is the bivalve (clams, oysters, mussels) or an enigmatic group of organisms called tusk shells. The work of the Vanderbilt phylogenists suggests that the conflict is due to the fact that the three groups diverged rapidly a long time ago.

“It has become common for top-notch studies to report genealogies that strongly contradict each other in where certain organisms sprang from, such as the place of sponges on the animal tree or of snails on the tree of mollusks,” said Antonis Rokas, Cornelius Vanderbilt Chair in Biological Sciences at Vanderbilt University.

In a study published online May 8 by the journal Nature, Rokas and graduate student Leonidas Salichos analyze the reasons for these differences and propose a suite of novel techniques that can resolve the contradictions and provide greater accuracy in deciphering the deep branches of life’s tree.

“The study by Salichos and Rokas comes at a critical time when scientists are grappling with how best to detect the signature of evolutionary history from a deluge of genetic data. These authors provide intriguing insights into our standard analytical toolbox, and suggest it may be time to abandon some of our most trusted tools when it comes to the analysis of big data sets. This significant work will certainly challenge the community of evolutionary biologists to rethink how best to reconstruct phylogeny,” said Michael F. Whiting, program director of systematics and biodiversity science at the National Science Foundation, which funded the study.

To gain insight into this paradox, Salichos assembled and analyzed more than 1,000 genes – approximately 20 percent of the entire yeast genome – from each of 23 yeast species. He quickly realized that the histories of the 1,000-plus genes were all slightly different from each other as well as different from the genealogy constructed from a simultaneous analysis of all the genes.

“I was quite surprised by this result,” Salichos pointed out.

By adapting an algorithm from information theory, the researchers found that they could use these distinct gene genealogies to quantify the conflict and focus on those parts of the tree that are problematic.

In broad terms, Rokas and Salichos found that genetic data is less reliable during periods of rapid radiation, when new species were formed rapidly. A case in point is the Cambrian explosion, the sudden appearance about 540 million years ago of a remarkable diversity of animal species, without apparent predecessors. Before about 580 million years ago, most organisms were very simple, consisting of single cells occasionally organized into colonies.

“A lot of the debate on the differences in the trees has been between studies concerning the ‘bushy’ branches that took place in these ‘radiations’,” Rokas said.

The researchers also found that the further back in time they went the less reliable the genetic data becomes. “Radioactive dating methods are only accurate over a certain time span,” said Rokas. “We think that the value of DNA data might have a similar limit, posing considerable challenges to existing algorithms to resolve radiations that took place in deep time.”

The research was supported by National Science Foundation CAREER award DEB-0844968.

Visit Research News @ Vanderbilt for more research news from Vanderbilt. [Media Note: Vanderbilt has a 24/7 TV and radio studio with a dedicated fiber optic line and ISDN line. Use of the TV studio with Vanderbilt experts is free, except for reserving fiber time.]

David F. Salisbury | Vanderbilt University
Further information:
http://www.vanderbilt.edu

More articles from Life Sciences:

nachricht Turning carbon dioxide into liquid fuel
06.08.2020 | DOE/Argonne National Laboratory

nachricht Tellurium makes the difference
06.08.2020 | Friedrich-Schiller-Universität Jena

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>