Featured Research

from universities, journals, and other organizations

Social Parasites Of The Smaller Kind

Date:
August 30, 2007
Source:
University of Chicago Press Journals
Summary:
Cooperation is widespread in the natural world but so too are cheats -- mutants that reap the benefits of others' cooperative efforts. In evolutionary terms, cheats should prosper, so how cooperation persists is puzzling. New research reveals that some cheats orchestrate their own downfall. The pathogen Pseudomonas aeruginosa cooperates to scavenge iron, but cheats steal the iron supplies. Cultures with fewer cheats thrived, to the benefit of the few cheats. Cultures with many cheats grew poorly.

Bacterial colonies of cooperators (green) and cheats (white), growing on agar. Cheats exploit cooperators by stealing their scavenged iron supplies.
Credit: Adin Ross-Gillespie

Cooperation is widespread in the natural world but so too are cheats -- mutants that do not contribute to the collective good but simply reap the benefits of others' cooperative efforts. In evolutionary terms, cheats should indeed prosper, so how cooperation persists despite the threat of cheat takeover is a fundamental question. Recently, biologists at the Universities of Edinburgh and Oxford have found that in bacteria, cheats actually orchestrate their own downfall.

In the study, reported in the September issue of The American Naturalist, the team explored the impact of cheats in populations of the notorious pathogen, Pseudomonas aeruginosa. These bacteria cooperate to scavenge iron from their environment, but mutant cheats do not contribute their fair share of scavenger molecules and instead simply steal the iron supplies of others.

"Cheats are kept in check by simple frequency dependence," says Adin Ross-Gillespie, lead author of the study. "When rare, cheats prosper at the expense of cooperators, but as they become more common, the profitability of their strategy declines. At equilibrium, neither strategy has the upper hand, so the two coexist."

But, the authors note, this pattern arises only under certain conditions. In this case, it arose because population productivity, too, was sensitive to the frequency of cheats. Cultures with few cheats grew rapidly and achieved larger absolute sizes in the time available, providing greater opportunity for cheats to exploit the situation. Meanwhile, cultures comprising high proportions of cheats grew poorly. "Too many cheats spoil the broth," quips Ross-Gillespie.

Microbes cooperate extensively, and their social activities often have profound medical or economic importance. Studies such as this help us to better understand how cooperative traits evolve and persist. Who knows" Perhaps some day we will harness the power of cheats to direct the dynamics of bacterial populations.

Reference: Adin Ross-Gillespie, Andy Gardner, Stuart A. West, and Ashleigh S. Griffin, "Frequency dependence and cooperation: theory and a test with bacteria" The American Naturalist (2007) volume 170: 331--342. DOI: 10.1086/519860


Story Source:

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


Cite This Page:

University of Chicago Press Journals. "Social Parasites Of The Smaller Kind." ScienceDaily. ScienceDaily, 30 August 2007. <www.sciencedaily.com/releases/2007/08/070824171156.htm>.
University of Chicago Press Journals. (2007, August 30). Social Parasites Of The Smaller Kind. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2007/08/070824171156.htm
University of Chicago Press Journals. "Social Parasites Of The Smaller Kind." ScienceDaily. www.sciencedaily.com/releases/2007/08/070824171156.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) 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