Posted on 02/23/2009 10:44:19 AM PST by Non-Sequitur
S EATTLE | In his voluminous writings, Charles Darwin made only brief mention of a little fish called the stickleback.
But 200 years after Darwin’s birth, the stickleback has become an unlikely superstar of evolutionary science.
Like the finches and tortoises of the Galapagos Islands that sparked Darwin’s theory, sticklebacks have adapted to myriad habitats in an evolutionary eye-blink. Scientists in Seattle, Canada and elsewhere now are using molecular techniques to study those adaptations, and their work is yielding the clearest insights yet into the way natural selection works at the genetic level.
(Excerpt) Read more at kansascity.com ...
“They (the fish) shed some of the heavy armor plates that protect against ocean predators but seem to hinder quick escapes in freshwater; they lost belly spines that proved a handicap with insects grabbing at the young fish from below. Sticklebacks that live on lake bottoms are almost always lighter in color than their marine counterparts, probably for camouflage.
Those patterns repeat around the world. Researchers say that means it’s not chance, but natural selection, behind the wheel.
“One of the beautiful things about the stickleback is that the process of colonizing new lakes and streams from the ocean has played out countless thousands of times,” said Stanford University developmental biologist David Kingsley, who has led much of the genetic work. “You’ve got all these natural experiments replicated over and over again.”
To replicate those experiments — but in a controlled way — Schluter built more than 30 ponds on the University of British Columbia’s Vancouver campus, each up to 75 feet square. He jokingly calls the complex his “evolution accelerator.””
At what point do these scientist predict the fish will acquire legs and wings?
As I recall (and I’ve been fed a lot of crap over my lifetime), when sticklebacks fight each other, the stickleback closest to his own nest wins.
Trust the MSM to skip the important questions:
What do they taste like?
And when nature does the ‘selective breeding’, it is called “Natural Selection”.
So you admit that natural selection can change a population with favored traits becoming more predominant within the population due to differential reproductive success?
The difference being that there is no artificial intervention in the actual selection process, by means of those tanks. That is, to show there is no external “intelligent” designer behind the adaptations.
With dogs, the breeder specifically chooses the mating partners.
“For several years, he and his students have been crossing and combining varieties of sticklebacks, throwing them in the ponds”
Yeah, this is a BREEDING PROJECT.
Of course you can get varieties of fish!!
Sheesh these evolutionist religious nutballs are so crazy to shove their religion down our throats.
I only know it from a line in Genesis’ “Carpet Crawlers”
“And the tickler takes his stickleback...”
I have no idea what it means, and I have listened to that song hundreds of times, and it’s still one of my favorites.
For what it’s worth:
Often compared to Darwin’s finches, the stickleback species pairs provide a powerful and tractable comparative model to test natural selection’s role in the speciation process. Although benthic and limnetic sticklebacks usually refuse to mate with each other, two benthics or two limnetics from different lakes that evolved in complete isolation for thousands of years will happily interbreed. “Repeatedly we see the same mechanism of reproductive isolation evolve in lock step with adaptation to their environment,” says UBC evolutionary biologist Dolph Schluter. “Natural selection is the only process that can do that.”
Scientists fear, however, that this so-called “natural laboratory system” doesn’t have enough replicates, especially as two of the five known species pairs have already been effectively wiped out by introduced species. Gow’s discovery - the first in more than two decades - is good news for conserving the critically endangered sticklebacks. But it’s also a boon for biological research.
Soon after bringing the fish back to her UBC lab, Gow walked down the hallway to Schluter’s office, Little Quarry Lake sticklebacks in hand. When Schluter saw the fish, he was immediately taken aback. “Oh my god, they sure looked like limnetics and benthics,” he recalls. Using genetic markers and morphological features, Gow and Schluter showed that the Little Quarry Lake sticklebacks were, indeed, a true species pair (Can J Zool, 86:564-71, 2008).
Gow and Schluter also found a fairly unique characteristic in the Little Quarry Lake benthic species: The fish lacked a pelvic girdle, the bony modified pelvic fin that is the equivalent of tetrapod hind limbs in most sticklebacks. Schluter had found this only once before in the five other British Columbia species pairs.
In 2004, together with geneticist David Kingsley at Stanford University, Schluter showed that regulatory changes in the Pitx1 gene led to pelvic girdle loss in both the benthics from Paxton Lake on Texada Island, BC, and in another population of nonpaired sticklebacks from Iceland (Nature, 428:717-23, 2004). Could the same mutation be at work in the Little Quarry Lake fish?
Kingsley and Schluter have already teased apart the genetic basis of another post-glacial stickleback feature: the loss of numerous protective armor plates. In 2005, they showed that a single mutation lurking at low frequencies in the marine ancestor was responsible for the parallel evolution of armor plate reductions in dozens of freshwater stickleback populations around the world (Science, 307:1928-33, 2005).
But armor plate changes are as “common as cockroaches,” says Kingsley. Since pelvic reductions are much rarer, they probably don’t stem from ancient, preexisting mutations, or we would see fewer freshwater girdles by now, he adds. Rather, each mutation causing pelvic reductions probably arose anew, including in the Little Quarry Lake benthic species. “That makes every single population of great interest,” says Kingsley.
Excerpt. Read more at: http://www.the-scientist.com/article/display/55360/
That is not fit for human consumption.
“For what it’s worth:”
No much: here’s why.
“a powerful and tractable comparative model to test natural selection’s role in the speciation process”
opening with a conclusion. not promising; classic manipulative technique. let’s see if it’s true.
“two benthics or two limnetics from different lakes that evolved in complete isolation for thousands of years”
LOL!! “evolved in complete isolation for thousands of years”. How do they know this? Did the stickleback tell them? I though evolution took millions of years, not mere thousands! that whole premise smells bad.
“Repeatedly we see the same mechanism of reproductive isolation evolve in lock step with adaptation to their environment”
what a load of tardedness. “mechanism of reproductive isolation” = they won’t mate, mate.
“Natural selection is the only process that can do that.”
ooh. another conclusion with nothing to back it up. I’m soooo impressed.
(blah filler)
“equivalent of tetrapod hind limbs in most sticklebacks. Schluter had found this only once before in the five other British Columbia species pairs.”
only once before!!?? wow.
“Could the same mutation be at work in the Little Quarry Lake fish?”
could you have ANY less to write about?
“post-glacial stickleback feature”
hey look, it’s a premise. everyone wave to the nice premise.
“they probably don’t stem from ancient, preexisting mutations”
oh I just looove “probably” articles, don’t you?
so, with a bunch of sciencey, high-sounding words to make you think they know what they are talking about, what they are basically saying is, there was a mutation, they don’t know why, they don’t know what, they don’t know where. but the have LOADS of premises and assumptions and conclusions and religious worldviews they’d just love to shove down your throat on the basis of it though.
Ha ha, I’ve got to hand it to ya!
Let’s see how the thread turns out... I’ll be checking back for any refutations to what you’ve just posted.
Evolution in Your FaceLake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!
by Patrick Huyghe
Omni
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