Featured Research

from universities, journals, and other organizations

How predictable is evolution?

Date:
February 19, 2013
Source:
Public Library of Science
Summary:
Understanding how and why diversification occurs is important for understanding why there are so many species on Earth. Researchers show that similar -- or even identical -- mutations can occur during diversification in completely separate populations of E. coli evolving in different environments over more than 1000 generations. Evolution, therefore, can be surprisingly predictable.

Under a magnification of 6836x, this colorized scanning electron micrograph (SEM) depicted a number of Gram-negative Escherichia coli bacteria of the strain O157:H7, which is one of hundreds of strains of this bacterium.
Credit: CDC/Janice Haney Carr

Understanding how and why diversification occurs is important for understanding why there are so many species on Earth. In a new study published on 19 February in the open access journal PLOS Biology, researchers show that similar -- or even identical -- mutations can occur during diversification in completely separate populations of E. coli evolving in different environments over more than 1000 generations. Evolution, therefore, can be surprisingly predictable.

The experiment, conducted by Matthew Herron, research assistant professor at the University of Montana, and Professor Michael Doebeli of the University of British Columbia, involved 3 different populations of bacteria. At the start of the experiment, each population consisted of generalists competing for two different sources of dietary carbon (glucose and acetate), but after 1200 generations they had evolved into two coexisting types each with a specialized physiology adapted to one of the carbon sources. Herron and Doebeli were able to sequence the genomes of populations of bacteria frozen at 16 different points during their evolution, and discovered a surprising amount of similarity in their evolution.

"In all three populations it seems to be more or less the same core set of genes that are causing the two phenotypes that we see," Herron said. "In a few cases, it's even the exact same genetic change."

Recent advances in sequencing technology allowed Herron and Doebeli to sequence large numbers of whole bacterial genomes and provide evidence that there is predictability in evolutionary diversity. Any evolutionary process is some combination of predictable and unpredictable processes with random mutations, but seeing the same genetic changes in different populations showed that selection can be deterministic.

"There are about 4.5 million nucleotides in the E. coli genome," he said. "Finding in four cases that the exact same change had happened independently in different populations was intriguing."

Herron and Doebeli argue that a particular form of selection -- negative frequency dependence -- plays an important role in driving diversification. When bacteria are either glucose specialists or acetate specialists, a higher density of one type will mean fewer resources for that type, so bacteria specializing on the alternative resource will be at an advantage.

"We think it's likely that some kind of negative frequency dependence -- some kind of rare type advantage -- is important in many cases of diversification, especially when there's no geographic isolation," Herron said.

As technology advances, Herron believes that similar experiments in larger organisms will soon be possible. Some examples of diversification without geographic isolation are known in plants and animals, but it remains to be seen whether or not the underlying evolutionary processes are similar to those in bacteria.


Story Source:

The above story is based on materials provided by Public Library of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Herron MD, Doebeli M. Parallel Evolutionary Dynamics of Adaptive Diversification in Escherichia coli. PLOS Biol, 11(2): e1001490 DOI: 10.1371/journal.pbio.1001490

Cite This Page:

Public Library of Science. "How predictable is evolution?." ScienceDaily. ScienceDaily, 19 February 2013. <www.sciencedaily.com/releases/2013/02/130219172155.htm>.
Public Library of Science. (2013, February 19). How predictable is evolution?. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2013/02/130219172155.htm
Public Library of Science. "How predictable is evolution?." ScienceDaily. www.sciencedaily.com/releases/2013/02/130219172155.htm (accessed July 26, 2014).

Share This




More Plants & Animals News

Saturday, July 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How to Make Single Serving Smoothies: Howdini Hacks

How to Make Single Serving Smoothies: Howdini Hacks

Howdini (July 24, 2014) Smoothies are a great way to get in lots of healthy ingredients, plus they taste great! Howdini has a trick for making the perfect single-size smoothie that will save you time on cleanup too! All you need is a blender and a mason jar. Video provided by Howdini
Powered by NewsLook.com
Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Newsy (July 24, 2014) A new study claims a set of prehistoric T-Rex footprints supports the theory that the giant predators hunted in packs instead of alone. Video provided by Newsy
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