An interesting change in the little Stickleback fish of a Washington State lake looks to be a good example of evolution, or even "reverse evolution," as this National Geographic article deems it.
Lake Washington, near Seattle, was quite a polluted mess in the 1960's. There was so much phosphorus-laden effluent coming into it that the water was dark and murky. The Stickleback fish that lived in the lake didn't need much protection from predators, and showed little of the armor plating of their nearby relatives in the salt water had, more closely resembling their freshwater relatives. Then the lake got cleaned up -- and the visibility increased. The cutthroat trout and other predators in the lake enjoy more than twice the visibility they had in the 60's. The sticklebacks show plenty of armament and stickers now, and it is very probably in direct response to the increased predator threat.
Since the biologists don't have samples of the fish from the turn of the century, they cannot make absolutely conclusive statements about "reverse evolution," but they can definitely demonstrate a change in phenotype in the fish, and point to a very likely selection pressure (the visibility in the water) that prompted it.
Cool stuff.
Enjoy clean lakes, and nature's quick response to said conditions,
BP
[article via "Yuri," photo credit in linked article]
2 comments:
Are We Not Fish? We are DEVO!
Good to see you sir.
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