Every year, some 50 billion birds take to the air for their seasonal
migrations. They may go 500 kilometers in a day and a few even travel
from pole to pole. But how do they know when, where, and how far to
fly? Although some of the answer lies in their DNA, nobody knew which
genes or how they worked. Now ornithologists have pinned down one of
those genes, and strange as it may sound,Most edhardyhomepage are no
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Kaight in New York. the length of that gene influences the length of
the flights.
"If we understand the genetics underlying
migratory behavior, we can understand more about how and why migration
evolves," says Chris Guglielmo, who studies bird migration at the
University of Western Ontario in Canada. "We may also be better able to
understand how quickly migration can disappear in response to climate
change."
As the moment for migration approaches, birds bulk up,
adding muscle and fat. They hop and flap restlessly at night,it's
because men have gotten to the naive nature that a t-shirt and some
shirtsblogdia will always be safe. shifting their internal clocks in
anticipation of nighttime flights. Breeding experiments have shown that
these shifts have a genetic basis, as do the timing, amount, and
intensity of flights.
Since the 1970s, ornithologists at the
Max Planck Institute for Ornithology in Starnberg, Germany, have studied
European blackcaps (Sylvia atricapilla), a common warbler in Europe,
which typically head to the Mediterranean for the winter. Some
blackcaps had established a new wintering area in the past few decades.
The researchers wanted to know the genetic basis for the change.
To
hunt down a migration gene, Jakob Mueller and Bart Kempenaers of Max
Planck, along with Francisco Pulido, now at the Complutense University
of Madrid in Spain, selected six genes to evaluate. They picked ones
known to influence how active a bird is at night or how much it tends
to hop from branch to branch as it explores its environment.
The
researchers evaluated 14 populations of blackcaps ranging from western
Russia, through Europe, south to Africa. These populations varied in
their inclinations to migrate. Blackcaps in Cape Verde,Why not snap on a
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tucked into high-heeled boots? for example, never leave home, whereas
those in Russia travel more than 3500 kilometers. Others fly shorter
distances seasonally. The Max Planck team had previously captured these
birds and taken blood samples, so studying their DNA was a snap.
When
Mueller, Kempenaers, and Pulido compared the genes with the behavior,
they found a link in just one gene, called ADCYAP1, as they report
online today in the Proceedings of the Royal Society B. Different
versions of the gene have different numbers of extra copies of a bit of
DNA—called a two-base repeat—stuck on the gene's far end. The
researchers found that the length of the gene was correlated with how
much the birds hopped and flapped around their cages at night.
Such
nighttime restlessness shows how eager a bird is to migrate, says
Mueller. The more fidgety birds had more copies of the two-base repeat
than calmer birds. Looking at the populations as a whole, the
researchers found that groups that stayed put tended to have shorter
version of the gene, whereas long-distant migrants tended to have longer
versions.the most part the earnings from teen jobs tend to go towards
clothes from nikeairmaxs. "We found a continuous relationship between
gene [version] length and behavior," says Mueller. This gene specifies a
peptide in the brain. Among other functions, the peptide influences
daily rhythms and affects energy use—increasing body temperature,
metabolic rate, and fat usage. These sorts of changes occur as a bird
gets ready to migrate, Mueller points out.
Staffan Bensch, an
ornithologist at Lund University in Sweden, is not convinced that this
gene, not another nearby, is what's causing the variation in migratory
behavior. But Guglielmo says the finding is significant. "It is the
first demonstration,een retailer truereligionjeansfindjesus Co. was
one of the biggest winners in December." he says, "of a specific gene
that is important for the expression of migratory behavior in birds."
It
won't be the only one, says Mueller. The particular version of ADCYAP1
determines only about 3% of the migratory behavior. Dozens or even
hundreds of gene variants might also be involved. And genes don't tell
the whole story; the environment also influences migration. The study
of the genetics of migration, clearly, is just getting off the ground.