such as "Introduction", "Conclusion"..etc
June 3, 2009 — What's the secret to surviving during times of environmental change? Evolve…quickly.
A new article in The American Naturalist finds that guppy
populations introduced into new habitats developed new and advantageous
traits in just a few years. This is one of only a few studies to look
at adaptation and survival in a wild population.
A research team led by Swanne Pamela Gordon from the University of
California, Riverside studied 200 guppies that had been taken from the
Yarra River in Trinidad and introduced into two different environments
in the nearby Damier River, which previously had no guppies. One Damier
environment was predator-free. The other contained fish that
occasionally snack on guppies.
Eight years after their introduction, the team revisited the Damier
guppies to see what adaptive changes they might have picked up in their
new environments. The researchers found that the females had altered
their reproductive effort to match their surroundings. In the
environment where predators were present, females produced more embryos
each reproductive cycle. This makes sense because where predators
abound, one might not get a second chance to reproduce. In less
dangerous waters, females produced fewer embryos each time, thus
expending fewer resources on reproduction.
Finally, the researchers wanted to see if these adaptive changes
actually helped the new population to survive. So they took more
guppies from the Yarra, marked them, and put them in the Damier
alongside the ones that had been there for eight years. They found that
the adapted guppies had a significant survival advantage over the more
recently introduced group.
In particular, juveniles from the adapted population had a 54 to 59
percent increase in survival rate over those from the newly introduced
group. In the long run, survival of juveniles is crucial to the
survival of the population, the researchers say.
The fact that fitness differences were found after only eight years
shows just how fast evolution can work—for short-lived species anyway.
"The changes in survival in our study may initially seem encouraging
from a conservation perspective," the authors write. "[B]ut it is
important to remember that the elapsed time frame was 13-26 guppy
generations. The current results may therefore provide little solace
for biologists and managers concerned with longer-lived species."
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