Scientists identify new 'social' chromosome in the red fire ant
foxnews.com |
Researchers
have discovered a social chromosome in the highly invasive fire ant that helps
to explain why some colonies allow for more than one queen ant, and could offer
new solutions for dealing with this pest. The red fire ants live in two
different types of colonies: some colonies strictly have a single queen while
other colonies contain hundreds of queens.
Publishing in the journal Nature on January 16, scientists have discovered
that this difference in social organisation is determined by a chromosome that
carries one of two variants of a 'supergene' containing more than 600 genes.
The two
variants, B and b, differ in structure but have evolved similarly to the X and
Y chromosomes that determine the sex of humans. If the worker fire ants in a
colony carry exclusively the B variant, they will accept a single BB queen, but
a colony that includes worker fire ants with the b variant will accept multiple
Bb queens. The scientists analysed the genomes of more than 500 red fire ants
to understand this phenomenon.
"This
was a very surprising discovery -- similar differences in chromosomal structure
are linked to wing patterns in butterflies and to cancer in humans but this is
the first supergene ever identified that determines social behaviour,"
explains co-author Dr Yannick Wurm, from Queen Mary's School of Biological and
Chemical Sciences.
"We
now understand that chromosomal variants determine social form in the fire ant
and it's possible that special chromosomes also determine fundamental traits
such as behaviour in other species."
During
the reproductive season, young winged queens from both types of colonies emerge
for their mating flights and are fertilised by males. Young queens destined to
establish their own single-queen colonies disperse far and wide. This social
form is highly successful at invading new territories. The other young queens
join existing multiple-queen colonies close to their maternal colony. The
multiple queens cooperating in such colonies are able to produce more workers
than are found in a single-queen colony. This makes multiple queen colonies the
more successful social form in busy environments.
The red fire ant is infamous for its painful sting in South
America where it is a native species, and in many other parts of the world
where its aggressiveness and high population density have made it an invasive
pest. It was accidentally introduced to the Southern USA in the 1930s and has
since spread to many warm parts of the world including China and Australia.
Efforts at controlling the spread of this species have largely been
unsuccessful, as indicated by its Latin name, Solenopsis invicta,
meaning "the invincible."
Dr.
Wurm added, "Our discovery could help in developing novel pest control
strategies. For example, a pesticide could artificially deactivate the genes in
the social chromosome and induce social anarchy within the colony."
Source: Queen Mary, University of
London
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