Posted on 11/30/2004 6:16:14 AM PST by presidio9
Swallows are getting sexier.
Male barn swallows attract females with long tail feathers, and European researchers have observed that over the last 20 years those feathers have become much longer.
"We've demonstrated quite a dramatic change in a short period of time," said Dr. Anders Pape Moller, an evolutionary biologist at Pierre and Marie Curie University in Paris, who conducted the research with Dr. Tibor Szep of the College of Nyiregyhaza in Hungary. The findings are to be published in The Journal of Evolutionary Biology.
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Experiments suggest that the males' tails act as advertising for good genes because males must be in good health to spend the energy growing them. The females, the researchers say, are particularly attracted by the tail's two outer feathers.
Dr. Moller, who has been documenting this preference for more than two decades, found that the outer feathers had lengthened by almost half an inch (11.4 millimeters), an increase of 10 percent, one of the biggest evolutionary shifts ever documented in a living population of wild animals. By contrast, the central tail feathers, which don't produce a reaction in females, haven't changed.
Over the last 30 years, researchers have made more than 1,500 measurements of natural selection in wild populations of animals and plants. Droughts on the Galápagos Islands, for example, have favored larger beaks in finches, because the surviving seeds are harder to crack. But the shift measured by Dr. Moller and Dr. Szep is greater.
Dr. Moller and Dr. Szep suspect that the agent for this is the long-term spread of the Sahara. The barn swallows they are examining migrate from Denmark to South Africa for the winter, then return by way of Algeria in the spring. The reduction of vegetation there around the desert may mean fewer insects for the hungry swallows.
"If they get across the Sahara and there's nothing to eat, it's tough," Dr. Moller said. Weaker male swallows starve; stronger ones reach Denmark. There they pass on their genes to the next generation - including genes for longer tails.
But that explanation has prompted some skepticism.
"I am prepared to believe that the birds are probably evolving, but not that climate change is the cause, simply because there can be so much else going on," said Dr. David Reznick, an evolutionary biologist at the University of California at Riverside.
Dr. Moller plans to search for more evidence.
The primary force of evolutionary development: Chicks dig it.
I doesn't take 20 years for them to develop on college women.
Most of the girls I knew in college developed a larger posterior in just one semester.
What I wanna know is if a barn swallow can really do that.
It's true, I read it in the Forum. ;o)
Bend ovah, lemme see ya shake ya tailfeathuhhhhh... :o)
LOL
Okay, what is it with the new tagline, Petronski?
It's from "One Night in Bangkok," a quirky song from the early 80s by Murray Head; the hit single was from a broadway play about love and intrigue at an international chess tournament.
High camp.
Ah haha!!! The second post-- it only took 2 posts!
I know the song. I was just wondering WHY a line from it has become part of your tagline. Yuh so silly sometimes.
I will now cease and desist from turning this thread into a chatroom conversation. (Where have all the good threads gone?)
A couple of us were hijacking a thread about a week ago with a discussion of the song, and it got stuck in my head.
Yeah, you wouldn't want to hijack a serious discussion like big butts on swallows...
ROFL! What's worse is how many threads I've posted to lately that have the word SEX in the title. uh oh
niiiiiiice one, ap
Have you run across cyborg and NYCGOPchick there? I always find them on 'those' threads.
Nice profile page you have there, BTW.
""I am prepared to believe that the birds are probably evolving, but not that climate change is the cause, simply because there can be so much else going on," said Dr. David Reznick, an evolutionary biologist at the University of California at Riverside." But wasn't Darwin's notion about survival of the fittest?
Thanks.
Personally, I don't post pics of myself because my wife would have to fight off the hordes of amorous ladies. And she's got enough to do trying to always fight me off.
Plus I'm too humble.
Speaking of profile pages, is that you in the THINK pic?
Yes. A very OLD photo. Like it? :o) Did you notice the extra hand?
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