Featured Research

from universities, journals, and other organizations

Biologists Propose New Grouping For Mammals: Key Deletion Offers Evidence For "Afrotheria"

Date:
February 2, 2001
Source:
University Of Cincinnati
Summary:
A team of biologists led by Mark Springer at the University of California, Riverside and including Ronald DeBry of the University of Cincinnati report in the Feb. 1 issue of Nature that an intensive analysis of DNA sequences provides strong support for a grouping Springer dubs "Afrotheria." The group includes a variety of placental mammals from elephants to elephant shrews. And add in aardvarks, manatees, and hyraxes to boot.

Cincinnati - What's missing might turn out to be as important as what's actually there in uncovering the roots of the mammalian tree of life.

A team of biologists led by Mark Springer at the University of California, Riverside and including Ronald DeBry of the University of Cincinnati report in the Feb. 1 issue of Nature that an intensive analysis of DNA sequences provides strong support for a grouping Springer dubs "Afrotheria." The group includes a variety of placental mammals from elephants to elephant shrews. And add in aardvarks, manatees, and hyraxes to boot.

"One of the problems with mammal phylogenies is there hasn't been a lot known," explained DeBry. "We were searching for the basic outline of the tree of life."

Traditional phylogenies, or evolutionary trees, were based on fossil evidence and physical similarities. To complicate things further, there was a huge explosion of mammalian groups right after dinosaurs went extinct.

"Finding the base of the tree has been difficult," said DeBry. "There are lots and lots of questions."

Over the last 10 years, DNA studies have confirmed some patterns proposed by those studying fossil evidence and physical similarities. Other DNA studies turned up new and unexpected relationships. The picture quickly got muddier and muddier.

"What we needed was a BIG data set," said DeBry. "Our data set has six different genes and 8600 base pairs." Two of the genes are found in mitochondrial DNA. The other four are found in the chromosomes of the nucleus, including BRCA-1, commonly known as the breast cancer gene.

Springer, DeBry and the other co-authors report that a specific deletion of nine base pairs in BRCA-1 is shared by 12 groups of placental mammals. These are the groups Springer puts together in "Afrotheria."

In addition, the exhaustive comparison helps to answer a more recent question: How closely are rabbits and guinea pigs related to rodents? The results in Nature indicate those groups should remain together, in contrast to previously published molecular results.

"Our data show a clearer picture," said DeBry. "The rodents, including the guinea pig, belong together. And rabbits probably do go with rodents."

On the other hand, a group known as Archonta should be split apart according to Springer et al. "The molecular data are really convincing that this isn't a group," said DeBry. "Bats are somewhere completely different. They're closer to pigs and cows than rodents and primates. Micro- and mega-bats go together with hedgehogs."

If this is starting to sound a bit confusing, the biologists have a very simple explanation for the divergence and resulting evolutionary tree. The relationships which evolved closely parallel the movement of continental land masses during geologic time.

That's why Springer named one group Afrotheria for its African origins and another Laurasiatheria after the land mass which gave rise to North America, Europe and Asia.

"Our results give a really strong division right at the base of the tree," noted DeBry. "Where did each group originate? One in the southern hemisphere and the other in the northern hemisphere. On the classic trees, the northern and southern groups are mixed up."

Geological evidence supports the phylogenies as well. Mammals first appeared in the fossil record about the time continents were splitting apart. This would give the different groups separate evolutionary histories, which is documented in the DNA analyses. "The DNA sequences tell us a nice biogeographic story," said DeBry. "We're not the first to see these relationships, but the evidence really hammers home the point that there is a group from Africa that is closely related."

The co-authors are: Ole Madsen and Wilfried deJong (University of Nijmegen, The Netherlands), Mark Scally, Christophe Douady, Heather Amrine and Mark Springer (University of California, Riverside), Ronald Adkins (University of Massachusetts), and Michael Stanhope (Queen's University of Belfast).

Funding was provided by the National Science Foundation and the European Commission's Training and Mobility of Researchers program.


Story Source:

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


Cite This Page:

University Of Cincinnati. "Biologists Propose New Grouping For Mammals: Key Deletion Offers Evidence For "Afrotheria"." ScienceDaily. ScienceDaily, 2 February 2001. <www.sciencedaily.com/releases/2001/02/010202073255.htm>.
University Of Cincinnati. (2001, February 2). Biologists Propose New Grouping For Mammals: Key Deletion Offers Evidence For "Afrotheria". ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/2001/02/010202073255.htm
University Of Cincinnati. "Biologists Propose New Grouping For Mammals: Key Deletion Offers Evidence For "Afrotheria"." ScienceDaily. www.sciencedaily.com/releases/2001/02/010202073255.htm (accessed August 22, 2014).

Share This




More Plants & Animals News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) — An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Newsy (Aug. 21, 2014) — According to a new study, spiders that live in cities are bigger, fatter and multiply faster. Video provided by Newsy
Powered by NewsLook.com
Lost Brain Cells To Blame For Sleep Problems Among Seniors

Lost Brain Cells To Blame For Sleep Problems Among Seniors

Newsy (Aug. 21, 2014) — According to a new study, elderly people might have trouble sleeping because of the loss of a certain group of neurons in the brain. Video provided by Newsy
Powered by NewsLook.com
Ramen Health Risks: The Dark Side of the Noodle

Ramen Health Risks: The Dark Side of the Noodle

AP (Aug. 21, 2014) — South Koreans eat more instant ramen noodles per capita than anywhere else in the world. But American researchers say eating too much may increase the risk of diabetes, heart disease and stroke. (Aug. 21) 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