Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Natural selection at single gene demonstrated

26.04.2006
Developed at the University of Southern California, test based on genomic data avoids pitfalls of older methods

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.

Carl Marziali | EurekAlert!
Further information:
http://www.usc.edu

More articles from Life Sciences:

nachricht Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>