Posted on 07/13/2006 1:21:13 PM PDT by presidio9
Finches on the Galapagos Islands that inspired Charles Darwin to develop the concept of evolution are now helping confirm it — by evolving.
A medium sized species of Darwin's finch has evolved a smaller beak to take advantage of different seeds just two decades after the arrival of a larger rival for its original food source.
The altered beak size shows that species competing for food can undergo evolutionary change, said Peter Grant of Princeton University, lead author of the report appearing in Friday's issue of the journal Science.
Grant has been studying Darwin's finches for decades and previously recorded changes responding to a drought that altered what foods were available.
It's rare for scientists to be able to document changes in the appearance of an animal in response to competition. More often it is seen when something moves into a new habitat or the climate changes and it has to find new food or resources, explained Robert C. Fleischer, a geneticist at the Smithsonian's National Museum of Natural History and National Zoo.
This was certainly a documented case of microevolution, added Fleischer, who was not part of Grant's research.
Grant studied the finches on the Galapagos island Daphne, where the medium ground finch, Geospiza fortis, faced no competition for food, eating both small and large seeds.
In 1982 a breeding population of large ground finches, Geospiza magnirostris, arrived on the island and began competing for the large seeds of the Tribulus plants. G. magnirostris was able to break open and eat these seeds three times faster than G. fortis, depleting the supply of these seeds.
In 2003 and 2004 little rain fell, further reducing the food supply. The result was high mortality among G. fortis with larger beaks, leaving a breeding population of small-beaked G. fortis that could eat the seeds from smaller plants and didn't have to compete with the larger G. magnirostris for large seeds.
That's a form of evolution known as character displacement, where natural selection produces an evolutionary change in the next generation, Grant explained in a recorded statement made available by Science.
agrred.
I just thought that the joke might bring you back into reality.
Get your own dirt placemarker
'High Confidence' That Planet Is Warmest in 400 Years;
Information Resources Related to Global Climate Change
From the admittedly little I have read of the research on Global warming and from the (few) scientists I have communicated with about global climate change, the consensus is that we are experiencing a global warming trend. Whether our impact is substantial, insignificant or something in between is undetermined.
If you have evidence that the consensus is wrong or that there is no consensus I would be interested in seeing the research.
Last I heard they acquired a taste for bananas.
Probably not. I doubt there is a single source for a chronology that encompasses such a wide range of beliefs as found in the creationist camp. I made the mistake of generalizing my assumption based on a single group of creationists and their literature. The best I could do would be to present literature from a single group of creationists who did at one time reject any change who now accept adaptation.
"I assume you've read or heard about this somewhere and could share your source. Thanks in advance for your reply."
My reply may take a while. I have a fair number of books to look through to find the initial reference.
LOL! A good one. So funny to watch as they try to 'outdo' God, The Creator of All.
Ah, well. So much for being original.
Your version seems to be original. Most of the rest were errors.
No, I'm not an expert on the matter, just a bystander. In terms of whether "global warming is happening" is an accurate statement, it seems to be a matter of whom one wants to believe I think.
Even if it is happening, I have serious doubts about claims that is is caused or even exacerbated by human activity however.
Excuse the diversion from the topic at hand.
That's okay, b_sharp, don't go to that much trouble. I just had never heard that assertion before and thought it might be interesting to read about it from a historical perspective.
So be it. It's a thought experiment then, one that demonstrates how well evoltuion explains biogeography.
Lets go again:
Evolution expects that newly formed remote islands such as Hawaii can only be populated by species from the mainland.
What I am doing is point out what the theory of evolution - ie the big explaination for the distribution of life on earth amongst other things expects.
Okay next point:
It expects that species on nearby mainlands would have a better chance of reaching the remote island than species on the otherside of the world.
You focus your disagreement with this one statement, but in general it is true. Hence species in Ireland are more similar to species in England than species in Australia. If what I said above was patently false then that shouldn't be the case. You are essentially nitpicking.
It therefore expects that island species will tend to be more similar to nearby mainland species than further away species. This is observed.
So it is.
And this is where you seem to have lost interest. Just as it got to the real hard hitting stuff that really supports evolution (the parts I have italicized) and afaik no other explaination really gets close to explaining this lot:
[evolution] also expects that certain classes of animal would be more likely to reach remote islands (birds) than others (land mammals) and therefore that remote islands should be heavily populated with birds at the expense of land mammals for example. Again this is observed. Remote islands tend to be dominated by the type of plants, insects and land mammals that would have had more chance of reaching those islands from the nearby mainland. It is no suprise under the evolution model that there are no native reptiles or amphibeans on hawaii, or that the only native mammals are bats.
Luck also plays a role as out of all types of birds on the nearby mainland only a few will reach a very remote island. Therefore evolution expects that only a fraction of mainland bird types, for example, will be represented on an island. This is observed - remote islands are sometimes missing even one species from a certain class of animal or plant, while having an abundance of species of another class.
Evolution expects that once a species does establish on the island it will diverge from it's ancestoral mainland species due to isolation and it will be very unlikely for it to travel elsewhere. Therefore evolution expects a high number of endemic species on remote islands - species that are found only on that island and nowhere else. This is observed.
Evolution also expects that one species which establishs on a remote island can found an ancestral tree of speciation to form an entire array of ancestral species on the island. Therefore evolution expects that while some classes of animal or plant might not be represneted at all, other classes will be heavily represented by many similar species. Again this is observed. Remote islands have such lop-sided distributions of organisms.
I too question the extent of our influence on the global climate. However, when you look at the changes humans can exert on the landscape through agriculture and ranching it seems reasonable that we can affect local temperature and moisture levels. How this translates to the global environment is, I'm afraid, beyond me.
Prime?
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