Featured Research

from universities, journals, and other organizations

Natural Selection At Single Gene Demonstrated

Date:
April 25, 2006
Source:
University of Southern California
Summary:
Wealth of genomic data makes it possible to identify mutations that cannot be attributed to chance.

Biologists seeking elusive proof of natural selection at the single-gene level have a powerful new tool at their disposal.

Chris Toomajian, postdoctoral researcher in molecular and computational biology in the USC College of Letters, Arts and Sciences, led a group that sought to replace the standard neutral model, a common but unrealistic test for natural selection, with a statistical method based on hard genomic data.

The group's research will be published online April 25 by Public Library of Science.

"Do we now have enough data to see the standard neutral model wasn't appropriate?" Toomajian asked. "We know something more now about how the population has been structured."

The standard neutral model makes improbable assumptions about population structure, such as assigning each individual an equal chance of reproducing.

Co-author Magnus Nordborg, associate professor of molecular and computational biology in USC College, predicted that earlier research would need to be revisited because the model makes it too easy to infer selection at any given gene.

"Once you start looking at enough cases then you realize that, oops, it's all under selection. I think a lot of that research is going to end up in the trash can," Nordborg said.

The group's method can be applied to any organism, including humans.

The PLoS paper focused on the weed Arabidopsis thaliana, and in particular on the FRIGIDA (FRI) gene, known to influence flowering time.

A. thaliana was once a plant that bloomed annually. But two versions of FRI that appeared thousands of years ago enabled the plant to flower year-round, helping it out-compete other plants.

Toomajian and his group showed that these two versions, also called gene variants, are too common to have spread solely by chance.

"We've shown that for one gene with an important role in that [flowering] process, there's good evidence that there's natural selection changing the behavior of the plants," Toomajian said.

Why the variants were selected remains unclear, though some have suggested that the plant evolved under pressure from the spread of agriculture.

Toomajian's group identified the gene variants through a comparison of 96 plants over 1,102 short fragments of the genome.

Each variant was assigned a score based on the similarity of two plants around the FRI gene relative to their similarity at other regions in the genome.

The higher the score, the less likely it is that a variant could have arisen and spread randomly.

The scoring formula accounts for the greater similarity expected in related plants.

Nordborg said that while natural selection is well documented at the whole-organism level, researchers consider biochemical proof of selection "the Holy Grail" of population genetics.

"What has proven very difficult is to connect specific molecular changes to selection," Nordborg said.

The PLoS paper, along with other recent studies based on intrinsic genomic comparisons, brings biology closer to this goal.

Major funding for the team's research came from the National Science Foundation. Researchers from the John Innes Centre at Norwich Research Park, U.K., contributed to the PLoS study.


Story Source:

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


Cite This Page:

University of Southern California. "Natural Selection At Single Gene Demonstrated." ScienceDaily. ScienceDaily, 25 April 2006. <www.sciencedaily.com/releases/2006/04/060425014814.htm>.
University of Southern California. (2006, April 25). Natural Selection At Single Gene Demonstrated. ScienceDaily. Retrieved September 3, 2014 from www.sciencedaily.com/releases/2006/04/060425014814.htm
University of Southern California. "Natural Selection At Single Gene Demonstrated." ScienceDaily. www.sciencedaily.com/releases/2006/04/060425014814.htm (accessed September 3, 2014).

Share This



More Plants & Animals News

Wednesday, September 3, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Snack Attack: Study Says Action Movies Make You Snack More

Snack Attack: Study Says Action Movies Make You Snack More

Newsy (Sep. 2, 2014) You're more likely to gain weight while watching action flicks than you are watching other types of programming, says a new study published in JAMA. Video provided by Newsy
Powered by NewsLook.com
Get A Mortgage, Receive A Cat — Only In Russia

Get A Mortgage, Receive A Cat — Only In Russia

Newsy (Sep. 2, 2014) The incentive is in keeping with a Russian superstition that it's good luck for a cat to be the first to cross the threshold of a new home. Video provided by Newsy
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
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