Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study shows animal family tree looking bushy in places

23.12.2005


The animal kingdom’s family tree is beginning to look a little bushy.



Two decades ago, with the advent of methods to look at the family relationships of different organisms by analyzing DNA, scientists envisioned it would only be a matter of time before the various family trees for plants, animals, fungi and their kin would be resolved with genetic precision.

And while molecular methods have had enormous success in ordering some branches in the tree of life -- mammals, for example -- and have played a critical role in refining and correcting trees constructed on the more traditional means of the appearance of organisms, the tree of animals remains fuzzy.


Now, scientists may know why this is so. Writing this week (Dec. 23, 2005) in the journal Science, a team of University of Wisconsin-Madison scientists led by Antonis Rokas, now of the Broad Institute of MIT and Harvard, suggests that a branch-by-branch account of animal relationships over a vast expanse of time is difficult to reconstruct because early animal evolution occurred in bunches.

"In general, we’d like to know who’s related to whom, and the pattern of the branches of the tree of life," says Sean Carroll, a Howard Hughes Medical Institute investigator at UW-Madison and the senior author of the Science paper.

But 500 million years of animal history on Earth is a lot of ground to cover, Carroll laments, and now it seems that the periodic, frenetic bursts of evolution that occurred at certain times in the distant past make sorting out animal relationships -- the branches on the tree -- extraordinarily difficult.

"It turns out that early in the origin of many types of animals, there were a lot of branching events in a short period of time," Carroll explains. Those type of episodes at key junctures in life’s history -- for example, the rise of complex animals or the migration of vertebrates from the sea to land -- make the animal tree look very bushy and very murky, Carroll’s group reports.

In the new Wisconsin study, which was also co-authored by Dirk Krüger of UW-Madison, massive amounts of molecular data for many animals were used to try to generate a clear picture of the animal tree.

"But instead of a tree, we got a bush where many branches sprout close together," Carroll says.

The group used the same approach to resolve the family tree of fungi, organisms that originated about the same time as animals. "In contrast to the animals, the tree of fungi, resolved neatly," Rokas explains. "The difficulty we are facing in telling animal relationships apart is evolution’s signature that some very interesting evolutionary stuff happened here."

It is not as if evolution of new forms of animal life occurred over night, says Carroll, a UW-Madison professor of genetics. The problem is that the resolution of branches that may have taken a few million years to sprout get washed out in the much larger context of 500 million years of animal life on Earth.

"It is hard to distinguish these events, even with boatloads of data," Carroll says. "As you go into deep time, origins are much harder to pick out. And given that there is so much data, you have to ask: why aren’t you getting any resolution?"

To illustrate the problem, Carroll notes that if 500 million years from now scientists were to use current molecular techniques to construct the radiation of mammals, they would have difficulty doing so because certain branching events are a "mere" few million years apart.

Using a computer model, Rokas and colleagues simulated just that scenario: What would the mammalian radiation look like had it not happened 100 million years ago, but instead 500-600 million years ago?

"The picture we get is surprisingly similar to the one we get for the animal kingdom," says Rokas. "Certain branches are well resolved, but others looked very bushy indeed."

"As you go into deep time, these bursts of evolutionary origins become harder to resolve," Carroll explains. In addition to the complications of deep time, animal life sometimes has a tendency to explode in radiations as organisms exploit new or newly vacant ecological niches. Famous examples of such radiations include, Darwin’s finches in the Galapagos and cichlid fish in African lakes.

In that respect, the results of the new study support paleontological evidence of an explosive radiation at the dawn of animal life.

To arrive at a definitive tree of life for animals, Carroll and Rokas believe, will require much more data and new techniques for extracting the information stored in the DNA record, which will enable scientists to look back in time with greater precision and distinguish the branching events that occurred as new species emerged.

"There are many, many cases where DNA has told us about species’ relationships that we never would have guessed based on appearances or other characteristics. We need this tree to understand the great story of animal evolution," Carroll says.

Sean Carroll | EurekAlert!
Further information:
http://www.wisc.edu

More articles from Studies and Analyses:

nachricht WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf

nachricht First form of therapy for childhood dementia CLN2 developed
25.04.2018 | Universitätsklinikum Hamburg-Eppendorf

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

When corals eat plastics

24.05.2018 | Ecology, The Environment and Conservation

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>