From: Dylan Sunter (dylan.sunter@fisystem.com)
Date: Wed Apr 17 2002 - 03:43:35 MDT
A species of Argentine ant introduced into Europe about 80 years ago has
developed the largest supercolony ever recorded.
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1932000/1932509.stm
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A species of Argentine ant introduced into Europe about 80 years ago has
developed the largest supercolony ever recorded.
It stretches 6,000 kilometres - from northern Italy, through the south of
France to the Atlantic coast of Spain - with billions of related ants
occupying millions of nests.
While ants from rival nests normally fight each other to the death, ants
from the supercolony have the ability to recognise each other and co-operate
- even if they come from nests at opposite ends of the colony's range.
The Argentine species (Linepithema humile) probably came into Europe on
imported plants, pushing back the 20 or so indigenous species of European
ant.
Scientists are not entirely sure why the supercolony has emerged. They think
the initial success of the alien invaders would have led to high nest
densities, which in turn would have favoured co-operative behaviour over
aggression.
And evolution would then have reinforced this superiority because nests
devoid of internal strife would have had time and resources to fight off
their enemies.
Success would have bred success.
"It is interesting to see that introduction in a new habitat can change
social organisation," said Professor Laurent Keller, of the University of
Lausanne, Switzerland, and one of the scientists to have identified the
supercolony.
"In this case, this leads to the greatest co-operative unit ever
discovered."
Smell the same
But Professor Keller and colleagues say the supercolony may be doomed.
Sooner or later, rivalries will emerge as genetically distinct groups of
ants turn against each other.
The supercolony itself also has a rival - a second, smaller supergroup of
Argentine ants holds sway in the Catalan region of Spain. These creatures
are more than happy to make war.
The ants would have come into Europe on imported plants
The research, by Swiss, French and Danish scientists, is published in The
Proceedings of the National Academy of Sciences.
Professor Jurgen Heinze, an expert on ants at Erlangen University, Germany,
is impressed with the work. He told the BBC there must be some important
genetic similarities running through the colony.
"An ant has to decide when encountering another individual whether this
individual belongs to its colony or not. The recognition cues are odours on
the surface of the ant and these odours are in part genetically based.
"Genetic variation leads to variation in the recognition cues and if there
is a loss of genetic variation, the ants all smell alike and they can no
longer distinguish between alien ants and nest mates."
Dylan Sunter
IT Systems & Networks Administrator
FiSystem UK
http://www.fisystem.com
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