How about 20 generations over an 8 year time frame!?

When Evolution Is Not So Slow And Gradual
ScienceDaily (June 3, 2009)
What's the secret to surviving during times of environmental change? Evolve…quickly.
Adapted from materials provided by University of Chicago Press Journals.

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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It's o.k. Nelson. I usually find your scientific explanations very helpful.

YES! Ring species. I couldn't think of the term. See there...very helpful indeed.
I had to go search for the answer to that and this is what I found in the methodology of one guppy study:

"We used a commercially available elastomer (Northwest Marine Technologies) and marked the fish with a subcutaneous injection in the caudal peduncle."

caudal peduncle: The narrow part of a fish's body to which the caudal or tail fin is attached.
LOL. This is just awesome.

I love this site and its members because, as you have proven StacyB, others are just as nerdy and want answers just as much as I do. Oh, a tattoo seemed reasonable and I was too lazy to figure it out for sure. But deep down I really did wonder.

Thank you. Both for your answer, and for making me feel like one of the crowd. (even if it is an awfully nerdy crowd!)
lulz. :D

StacyB :hearts: the nerds!!!

Besides, who doesn't want to know how researchers manage to mark 10 mm fish?!
Speaking of dogs and species...
Interesting article. The comments below are interesting as well (and worth reading).
I've always agreed with this.
Evolution of the banana.

Wild banana:

Banana with the help of mankind:

Eat that, Ray Comfort.
Of course, the problem with pointing to examples like this (and all the forms of dog we've bred from wolves) is that creationists point to the fact that this "evolution" (because, yes, they'll use air quotes, a/k/a "dick fingers") was guided by an intelligent force - humans. This gives them an in to argue that these changes happen because someone makes them happen rather than by "chance." (Again with the dick fingers.)
But are they perfectly designed for humans? Cuz I saw this guy online who said so and he sounded pretty smart.
j/k ;)
I don't know if it's considered evolution, technically, but they've demonstrated epigenetic changes in plants and mice just by altering environmental constants or diet.
We have recently demonstrated that exposure of pregnant mice to bisphenol A (BPA), a building block of polycarbonate plastics and epoxy resins used to make consumer items ranging from water bottles to dental sealants, significantly reduces DNA methylation in Avy mice (Dolinoy et al., Proc. Natl. Acad. Sci. USA 104: 13056-13061, 2007). This results in the birth of more yellow offspring, mice that become obese and have a higher incidence of diabetes and cancer as adults. Thus, there could be a connection between the increase in plastics in our environment and the rising incidence of obesity in humans. However, such an association will not be able to be demonstrated unequivocally until the expression and function of genes involved in human obesity are shown to be altered by BPA.
[Editor's note: For more on the agouti mice, see A Tale of Two Mice.]


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