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Author Topic:   Galapagos finches
PaulK
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Message 2 of 104 (84334)
02-07-2004 6:11 PM
Reply to: Message 1 by Tamara
02-07-2004 10:05 AM


Have you any objective measure of how different the finches are ? The variations in humans seem obvious to us but genetically we really are't that different.
Drawing a fine line between sub-species and species is not possible and there are always arguments (which is to be expected given that new species do form by evolution), however I do not think that there is any reasonable chance that the "finches" represent a single species.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 4 of 104 (84444)
02-08-2004 10:10 AM
Reply to: Message 3 by Tamara
02-08-2004 10:01 AM


Well Wells is not exactly trustworthy but even if he is correct here, six is still significantly greater than one.
This essay comments on Wells claims about the Galapagos finches
Jonathan Wells and Darwin's Finches

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 7 of 104 (84498)
02-08-2004 3:11 PM
Reply to: Message 6 by Tamara
02-08-2004 2:51 PM


Let us be clear. According to the quote Grant thinks that six is the minimum based on the current data and only that new data *might* reduce the number further. So the idea that there's just one species is a pretty much a non-starter.
And why do you say that biology is "trivialising" the concept of species ? The definition is being adjusted to try and deal with the very real problems of taxonomy because we don't have clear boundaries - as evolution predicts.
[This message has been edited by PaulK, 02-08-2004]

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 9 of 104 (84506)
02-08-2004 3:51 PM
Reply to: Message 8 by Tamara
02-08-2004 3:29 PM


Well if you really think that small birds have the intelligence to set up inward-looking communities on the same basis as the Chassids then you might have a point.
But lack of interfertility isn't even appropriate to asexually reproducing species - and that includes at least one vertebrate species (whiptail lizards).
On the other heand we have so-called "cryptic" species which are almost impossible to distinguish by their physical forms, yet do not interbreed.
I hadn't heard that coyotes had been classified as the same species as wolves - but it wouldn't surprise me. Taxonomy is a constant battle between "lumpers" and "splitters".
Then there are other species concepts, such as the ecological species concept or the recognition species concept.
No single species concept actually works perfectly.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 12 of 104 (84517)
02-08-2004 4:47 PM
Reply to: Message 10 by Tamara
02-08-2004 4:23 PM


Unless the evidence actually indicates that the "finches" are best classified as a single species - and so far there is only a chance that the number could be finally reduced to less than six, which is the lowest number suggested by the most recent data we do have there's a very good case that we do have a genuine example of speciation here.
And it is hardly the only example we have.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 14 of 104 (84523)
02-08-2004 5:50 PM
Reply to: Message 13 by Tamara
02-08-2004 5:10 PM


In case you haven't noticed I haven't been disagreeing with the Grants at all. You're the one who wants to jump to there only being one species, and that isn't supported at all.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 20 of 104 (84631)
02-09-2004 2:49 AM
Reply to: Message 16 by Tamara
02-08-2004 9:27 PM


I suggest that you reread the quote. It is clear to me that Grant means the most extreme *Reduction* in the number of species which gives us six as a minimum on current data - as I have said all along
On that basis we have six as the minimum currently supported and only a possibility of any reduction below that.
Is it reasonable to trust the speciation claim - YES. Grant explictly states that even after reduction there are two species on a single island.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 30 of 104 (84705)
02-09-2004 11:39 AM
Reply to: Message 21 by Tamara
02-09-2004 10:02 AM


Yeah, well, if 14 bogus species that should be really six or possibly fewer in the words of THE expert does not strike you as gross exageration, what can I say? I guess my gullibility meter is more finely calibrated than yours
That is a serious misrepresentation of the actual situation.
We do not have 14 bogus species. Instead we have a population classified as 14 species by one criterion that MAY be as few as six when classified by another.
I think your bias is showing.
Oh and what DOES Wells have to say about "gill slits" ? The structure is there in vertebrate embryos, and it is genuine evidence of evolution even though Wells doesn't like it.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 44 of 104 (84921)
02-10-2004 2:42 AM
Reply to: Message 34 by Tamara
02-09-2004 3:21 PM


SO baiscally you expect me to disagree with the quote you produced and agree with some vague references you produced. And you say that *I* have to come up with something better ?
The simple fact is that there are a number of different definitions of species. NONE of them is entirely adequate. How do you think the Galapogos "finches" were originally classified ?
And no, I'm not "baiting" you over the "gill slits". Here is a structure in vertebrate embryos that is referred to as "gill slits". There are no gills but the "gill slits" are there and that is evidence of evolution. It isn't a propaganda term as you claim - it's just an old term that was coined before people knew better and has stuck. Now *WElls* is propaganda - and your misrepresentations of the Galapagos "finches" is propaganda but the "gill slits' aren't.
Now I may not be bias fee but at least I do make the effort to evaluate the claims of the other side fairly. Unlike you.
Nor do I misrepresent my position as you do :
"I am not here to convince anyone. I am here to make up my mind." (Post 16).
It's obvious that you have made up your mind and you refuse to learn.
"MrH, you make a lot of unwarranted assumption about my point of view. I am not against evolution, or science." (Post 21)
Well it is obvious that you *are* against evolution.
And no, humans do not vary as greatly as dogs.

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 50 of 104 (84967)
02-10-2004 9:06 AM
Reply to: Message 47 by Tamara
02-10-2004 8:27 AM


I'm not out of argument by any means. The question is are you prepared to listen ? Your responses indicate otherwise. I have tied - really tried - to point out the facts to you. And I get responses like "are you baiting me ?"

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PaulK
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Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 55 of 104 (85057)
02-10-2004 2:06 PM
Reply to: Message 51 by truthlover
02-10-2004 9:33 AM


The reduction to six species is not "better" unless you believe that strict application of a definition based on interfertility is "best".
But taxonomists in general do not absolutely enforce this rule (ducks are an example where hybridisation is a real problem - notoriously in the case of imported Ruddy Ducks and Spanish White-Tailed Ducks).
Having done a little more investigation I have discovered that the "finches" are diverse enough that they are usually classified as belonging to 3 or more genera. I don't know why (although I might look further) but even if the finches are superficially the same the differences must be significant enough that it is very unlikely that there is only a single species.
As I have said earlier on there are several different definitions of "species" and there is no agreement that one is "the" definition.

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PaulK
Member
Posts: 17852
Joined: 01-10-2003
Member Rating: 4.0


Message 59 of 104 (85301)
02-11-2004 2:28 AM
Reply to: Message 57 by NosyNed
02-10-2004 7:13 PM


Re: waiting
So far as I can see Tamara wants an excuse to attack evolution and science so she turned nasty as soon as it was pointed out that her speculation that the finches were a single species wasn't reasonable based on the evidence available.

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