Featured Research

from universities, journals, and other organizations

Tree Of Animal Life Has Branches Rearranged, By Evolutionary Biologists

Date:
March 6, 2008
Source:
Brown University
Summary:
Evolutionary biologists have re-written the animal tree of life. A new study uses new genomics tools to answer old questions about animal evolution -- and offers up a few surprises among the branches. The study involved 40 million base pairs of new DNA data taken from 29 animal species. It settles some long-standing debates about the relationships between major groups of animals and offers up a few surprises. The big shocker: Comb jellyfish -- common and extremely fragile jellies with well-developed tissues -- appear to have diverged from other animals even before the lowly sponge, which has no tissue to speak of. This finding calls into question the very root of the animal tree of life, which traditionally placed sponges at the base.

Big shocker: Comb jellyfish -- common and extremely fragile jellies with well-developed tissues -- appear to have diverged from other animals even before the lowly sponge, which has no tissue to speak of. This finding calls into question the very root of the animal tree of life, which traditionally placed sponges at the base.
Credit: NOAA

A study led by Brown University biologist Casey Dunn uses new genomics tools to answer old questions about animal evolution. The study is the most comprehensive animal phylogenomic research project to date, involving 40 million base pairs of new DNA data taken from 29 animal species.

The study, which appears in Nature, settles some long-standing debates about the relationships between major groups of animals and offers up a few surprises.

The big shocker: Comb jellyfish -- common and extremely fragile jellies with well-developed tissues -- appear to have diverged from other animals even before the lowly sponge, which has no tissue to speak of. This finding calls into question the very root of the animal tree of life, which traditionally placed sponges at the base.

"This finding suggests either that comb jellies evolved their complexity independently from other animals, or that sponges have become greatly simplified through the course of evolution. If corroborated by other types of evidence, this would significantly change the way we think about the earliest multicellular animals," said Dunn, assistant professor of ecology and evolutionary biology at Brown. "Coming up with these surprises, and trying to better understand the relationships between living things, made this project so fascinating."

Charles Darwin introduced the idea of a "tree of life" in his seminal book Origin of Species. A sketch of the tree was the book's only illustration. Nearly 150 years after its publication, many relationships between animal groups are still unclear. While enormous strides have been made in genomics, offering up a species' entire genome for comparison, there are millions of animal species on the planet. There simply isn't the time to sequence all these genomes.

To get a better grasp of the tree of life -- without sequencing the entire genomes of scores of species -- Dunn and his team collected data, called expressed sequence tags, from the active genes of 29 poorly understood animals that perch on far-flung branches of the tree of life, including comb jellies, centipedes and mollusks. The scientists analyzed this data in combination with existing genomic data from 48 other animals, such as humans and fruit flies, looking for the most common genes being activated, or expressed.

The aim of this new approach is to analyze a large number of genes from a large number of animals -- an improvement over comparative genomics methods which allow for a limited analysis of genes or animals. The new process is not only more comprehensive, it is also more computationally intensive. Dunn's project demanded the power of more than 120 processors housed in computer clusters located in laboratories around the globe.

Dunn and his team:

  • unambiguously confirmed certain animal relationships, including the existence of a group that includes invertebrates that shed their skin, such as arthropods and nematodes;
  • convincingly resolved conflicting evidence surrounding other relationships, such as the close relationship of millipedes and centipedes to spiders rather than insects;
  • established new animal relationships, such as the close ties between nemerteans, or ribbon worms, and brachiopods, or two-shelled invertebrates.

"What is exciting is that this new information changes our basic understanding about the natural world -- information found in basic biology books and natural history posters," Dunn said. "While the picture of the tree of life is far from complete after this study, it is clearer. And these new results show that these new genomic approaches will be able to resolve at least some problems that have been previously intractable."

The study team included Andreas Hejnol, David Matus, Kevin Pang, William Browne, Elaine Seaver and Mark Martindale from the University of Hawaii; Stephen Smith from Yale University; Greg Rouse from the University of California--San Diego; Matthias Obst from Kristineberg Marine Research Station in Sweden; Gregory Edgecombe from The Natural History Museum in London; Martin Sorensen and Reinhardt Kristensen from the University of Copenhagen; Steven Haddock from the Monterey Bay Aquarium Research Institute; Andreas Schmidt-Rhaesa from the University of Hamburg in Germany; Akiko Okusu from Simmons College; Ward Wheeler from the American Museum of Natural History; and Gonzalo Giribet from Harvard University.

The National Science Foundation funded the work through its Assembling the Tree of Life (AToL) project.


Story Source:

The above story is based on materials provided by Brown University. Note: Materials may be edited for content and length.


Cite This Page:

Brown University. "Tree Of Animal Life Has Branches Rearranged, By Evolutionary Biologists." ScienceDaily. ScienceDaily, 6 March 2008. <www.sciencedaily.com/releases/2008/03/080305144221.htm>.
Brown University. (2008, March 6). Tree Of Animal Life Has Branches Rearranged, By Evolutionary Biologists. ScienceDaily. Retrieved August 31, 2014 from www.sciencedaily.com/releases/2008/03/080305144221.htm
Brown University. "Tree Of Animal Life Has Branches Rearranged, By Evolutionary Biologists." ScienceDaily. www.sciencedaily.com/releases/2008/03/080305144221.htm (accessed August 31, 2014).

Share This




More Plants & Animals News

Sunday, August 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Newsy (Aug. 29, 2014) In a new study, a promising experimental treatment for Ebola managed to cure a group of infected macaque monkeys. Video provided by Newsy
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins