Featured Research

from universities, journals, and other organizations

Small insect with a big heart: 'Giving' aphids endangered by their selflessness

Date:
February 8, 2010
Source:
University of Royal Holloway London
Summary:
One of the founding principles of Darwin's theory is that biological evolution has been shaped by the survival of the fittest. Things, however, are not always that simple as researchers have discovered while analyzing the social behavior of aphids. A few aphid species have "soldiers" who stop reproducing and instead contribute to the public good. Not only do they risk their lives to defend the nest from invaders, but they also mend and clean it.

Colony of aphids at early stage.
Credit: iStockphoto/Michael Pettigrew

One of the founding principles of Darwin's theory is that biological evolution has been shaped by the survival of the fittest. Things, however, are not always that simple as researchers from Royal Holloway, University of London have discovered while analysing the social behaviour of aphids.

A few aphid species have "soldiers" who stop reproducing and instead contribute to the public good. Not only do they risk their lives to defend the nest from invaders, but they also mend and clean it. The repair work involves the aphids secreting a glue-like substance from their bodies -- comprising two thirds of their body size. They use their legs to mix it and form a scab. But many of the soldier aphids die from the significant loss of body mass. Without the soldiers' efforts all the aphids could be destroyed by a predator or the nest could fall apart.

Researchers from Royal Holloway wanted to discover whether the selfless behaviour of the soldiers was putting them in danger of being wiped out by selfish free-riders who come to inhabit the nests. These "immigrant" aphids do not contribute to the running of the nest and continue to reproduce at a normal rate. An average nest will have 25% immigrants, allowing free-riders a chance to spread throughout the population at large, similar to the spread of a tumour.

The study, "The impact of colonial mixing on the evolution of social behaviour in aphids," is being published in Proceedings of the Royal Society B (3 February 2010). Dr John Bryden, from the School of Biological Sciences at Royal Holloway, said, "We are interested in understanding why animals are nice to each other -- why they show social behaviour. This is puzzling because, in a fiercely competitive fight for resources, helping others seems like a fool's game."

The academics attempted to answer the question by making a mathematical model. "It turned out that the complex lifecycle of the aphids can be captured in simple numbers expressing levels of relatedness, that help understand why social behaviour can evolve. What surprised us is not that this is possible, this has long been known, but that something so difficult can be boiled down to something so simple," says Vincent Jansen, Professor of Mathematical Biology at Royal Holloway.

"We know that helping behaviour can evolve if the recipient is more likely than an average member of the population to show the same behaviour. This likelihood of being the same is called relatedness. As relatedness is increased, more helpful behaviour will evolve. What isn't well known is how we can predict the relatedness of a population and how that will affect the levels of social behaviour," says Dr Bryden.

The study shows how it is possible to reduce the complex system of aphids growing, living in, and migrating between nests down to a simple equation -- predicting the relatedness of the aphid system.

"We have discovered that immigration can reduce the level of social behaviour, but that the quite surprising levels of immigration that we see in aphids is still not sufficient to trigger a full-scale collapse of the aphid's societies," adds Dr Bryden.

The scientists say the model they have created can be reused, with additions and modifications, to try and understand more complex social behaviour in other animals.

Dr Bryden, said, "The goal of modelling and understanding human societies is still a long way away, but we hope that through tackling increasingly complex biological systems we can take steps toward that goal."


Story Source:

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


Cite This Page:

University of Royal Holloway London. "Small insect with a big heart: 'Giving' aphids endangered by their selflessness." ScienceDaily. ScienceDaily, 8 February 2010. <www.sciencedaily.com/releases/2010/02/100202193629.htm>.
University of Royal Holloway London. (2010, February 8). Small insect with a big heart: 'Giving' aphids endangered by their selflessness. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2010/02/100202193629.htm
University of Royal Holloway London. "Small insect with a big heart: 'Giving' aphids endangered by their selflessness." ScienceDaily. www.sciencedaily.com/releases/2010/02/100202193629.htm (accessed August 29, 2014).

Share This




More Plants & Animals News

Friday, August 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Raw: Australian Sheep Gets Long Overdue Haircut

Raw: Australian Sheep Gets Long Overdue Haircut

AP (Aug. 28, 2014) Hoping to break the record for world's wooliest, Shaun the sheep came up 10 pounds shy with his fleece weighing over 50 pounds after being shorn for the first time in years. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Minds Blown: Scientists Develop Fish That Walk On Land

Minds Blown: Scientists Develop Fish That Walk On Land

Newsy (Aug. 28, 2014) Canadian scientists looking into the very first land animals took a fish out of water and forced it to walk. Video provided by Newsy
Powered by NewsLook.com
Fake Dogs Scare Real Geese from Wis. Park

Fake Dogs Scare Real Geese from Wis. Park

AP (Aug. 28, 2014) Parks officials in Stevens Point, Wisconsin had a fowl problem. Canadian Geese were making a mess of a park, so officials enlisted cardboard versions of man's best friend. (Aug. 28) 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