Featured Research

from universities, journals, and other organizations

Orphan army ants join nearby colonies

Date:
November 18, 2009
Source:
Harvard University
Summary:
Colonies of army ants, whose long columns and marauding habits are the stuff of natural-history legend, are usually antagonistic to each other, attacking soldiers from rival colonies in border disputes that keep the colonies separate. But new work shows that in some cases the colonies can be cooperative instead of combative.

Army ants are group predators that overwhelm large arthropods and other social insect colonies. Here, a raiding swarm of Dorylus molestus is attacking a grasshopper at Mt Kenya.
Credit: Daniel Kronauer/Harvard University

Colonies of army ants, whose long columns and marauding habits are the stuff of natural-history legend, are usually antagonistic to each other, attacking soldiers from rival colonies in border disputes that keep the colonies separate. But new work by a researcher at the Harvard Museum of Comparative Zoology and colleagues at the University of Copenhagen shows that in some cases the colonies can be cooperative instead of combative.

In those cases, when an army ant colony loses its queen, its workers are absorbed, not killed, by neighboring colonies, and within days are treated as part of the family.

The research, conducted in an ant-rich area on the slopes of Mount Kenya, is detailed in the journal Proceedings of the Royal Society B.

Army ant colonies are dominated by a single, large queen who produces the eggs that give rise to all of the colony's individuals, which can number millions of workers. When she dies, colonies quickly disappear, raising the question of what happens to the many individuals.

The work was conducted by Daniel Kronauer, a junior fellow in Harvard's Society of Fellows, over two field seasons in Kenya. Kronauer and his colleagues followed the fates of 10 army ant colonies whose queens they had removed. The researchers lost track of two of the colonies but observed two distinct strategies used by the remaining eight.

Most of the queenless colonies, seven out of 10, simply joined a neighboring colony -- determined by genetic analysis -- with the new workers slowly losing their distinct colony odor, and within days becoming fully integrated.

The last queenless colony stayed on its own, with workers employing a strategy of producing a small brood of winged males. Though these males were removed for analysis, in an undisturbed colony the males would fly off looking for young unmated queens. Though this strategy does provide some chance of passing along the colony's genes, the small number of males produced -- just 31 in this case compared with 3,000 in a fully functioning colony -- illustrates that this strategy may not be efficient.

"It is a last option to get some fitness returns before they die," Kronauer said.

Though the work illuminates where most of the ants go, it doesn't entirely settle the question of why. Though it makes sense that the accepting colony would want to increase its size and competitiveness by gaining many new workers, the evolutionary drivers behind the queenless colony's workers absorbing into the new colony are more vague.

Since workers are normally kept from reproducing, Kronauer and his co-authors found, there doesn't seem to be a direct fitness benefit. Instead, the authors suggested that the fusing colonies are driven by indirect fitness benefits gained because of distant relationships between colonies, and they called for more fieldwork to explore the issue further.

Kronauer's co-authors are Caspar Sch๖ning, Patrizia d'Ettorre, and Jacobus J. Boomsma, all of the Centre for Social Evolution, Department of Biology, University of Copenhagen. Financial support was provided by the Danish National Research Foundation and the Alexander von Humboldt Foundation.


Story Source:

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


Cite This Page:

Harvard University. "Orphan army ants join nearby colonies." ScienceDaily. ScienceDaily, 18 November 2009. <www.sciencedaily.com/releases/2009/11/091104122532.htm>.
Harvard University. (2009, November 18). Orphan army ants join nearby colonies. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2009/11/091104122532.htm
Harvard University. "Orphan army ants join nearby colonies." ScienceDaily. www.sciencedaily.com/releases/2009/11/091104122532.htm (accessed August 21, 2014).

Share This




More Plants & Animals News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Possible Ebola Patient in Isolation at California Hospital

Possible Ebola Patient in Isolation at California Hospital

Reuters - US Online Video (Aug. 20, 2014) — A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) — Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Unsustainable Elephant Poaching Killed 100K In 3 Years

Unsustainable Elephant Poaching Killed 100K In 3 Years

Newsy (Aug. 20, 2014) — Poachers have killed 100,000 elephants between 2010 and 2012, as the booming ivory trade takes its toll on the animals in Africa. Video provided by Newsy
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. 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