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 Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>