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Author Topic:   Galapagos finches
Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 5 of 104 (84448)
02-08-2004 10:45 AM
Reply to: Message 3 by Tamara
02-08-2004 10:01 AM


I think the Grants' work just reinforces the concept that ol' Mother Nature is a lot messier than we humans would like her to be - we want a species to be a single thing that we can hold the archetype for in our hand, and reality just isn't that way. Johnathan Weiner's The Beak of the Finch is a pretty readable summary of the Grants' studies, BTW.

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Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 23 of 104 (84686)
02-09-2004 10:33 AM
Reply to: Message 21 by Tamara
02-09-2004 10:02 AM


Problem with your argument is... if chihuahuas and St. Bernards would not be considered one species "in the wild" then why should Icelanders and Bantus be considered one species?
The physical (as opposed to geographical) barrier to interbreeding of chihuahuas and St Bernards is a tad higher than that between any two populations of humans, don't you think?

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Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 39 of 104 (84778)
02-09-2004 3:54 PM
Reply to: Message 35 by Tamara
02-09-2004 3:27 PM


As for whether Grant meant at least 6 or at most 6, I admit the quote is ambiguous.
In the 1992 paper - Science, vol 256, pp 193-197 - the Grants write, after discussing by name the three species of Geospiza on the island Daphne Major
A parallel study on Genovesa island gave similar estimates of the frequency of hybridization among the three other species in the genus of Darwin's finches.
That's the only mention I can find there of the total number of species. Tamara, PM or email me if you want a copy of the whole paper - copyright laws won't let me post it here.

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Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 46 of 104 (84962)
02-10-2004 8:25 AM
Reply to: Message 42 by Tamara
02-09-2004 11:19 PM


Re: Thank you Coragyps!
You're welcome, Tamara. But try to avoid the appearance of "quote mining" - it'll bring you grief in these here parts. The Grants do, indeed, write "The discovery of superior hybrid fitness over several years suggests that the three study populations of Darwin's finches [on Daphne] are fusing into a single panmictic population, and calls into question their designation as species."
But the next sentence is "Over the long term, fusion is unlikely." The next paragraph summarizes some reasons for this opinion. And the major portion of the paper describes just how common hybridization is among the birds: 9.2% of all species have been documented to crossbreed in the wild, with the number rising to 40%+ in the order that contains ducks and geese. Darwin's finches aren't some odd outlier to the "rules" - they're just exceptionally well studied.

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Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 82 of 104 (335316)
07-25-2006 9:06 PM
Reply to: Message 81 by MurkyWaters
07-25-2006 8:07 PM


Re: here we go ...
I challenge you to come up with any examples of observed changes in nature which increase informational (genetic) content.
I can do that. The point mutation that led to hemoglobin C in the Mossi and related peoples of West Africa. They make a variant form of hemoglobin - somewhat like that of sickle-cell anemia - that makes homozygotes nearly immune to ill effects from malaria. And most folks with HbC never know they have it.
Of course, the hemoglobin S or sickle-cell mutation also adds "informational content," for English definitions of those words, to the genome. Two kinds of hemoglobin require more "instructions" to manufacture than one kind does.
The original created kinds of organisms were genetically information rich...
And how were they "genetically information rich?" Tetraploid? Hexadecaploid? How many alleles did they have for various traits like the wrinkled vs smooth seeds in Mendel's peas?
God created the universe and all life approximately 6000 years ago according to the historical account from the bible which includes the occurrence of a worldwide flood. That statement is the initial and un-provable axiom
Ah, but that "axiom" has been disproved by a couple of dozen or more separate lines of investigation from biology, geology, chemistry, astronomy, and physics. No flood. 45,000 varves in Lake Suigetsu and the Cariaco Basin. 700,000 layers in the ice in Antarctica.
But I'm veering off from finches......
See you around the forums!

This message is a reply to:
 Message 81 by MurkyWaters, posted 07-25-2006 8:07 PM MurkyWaters has replied

Replies to this message:
 Message 83 by MurkyWaters, posted 07-26-2006 1:16 AM Coragyps has replied

  
Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 85 of 104 (335394)
07-26-2006 7:50 AM
Reply to: Message 83 by MurkyWaters
07-26-2006 1:16 AM


Re: here we go ...
I dispute your "sickle-cell" example as adding informational content. Nearly all mutations are harmful or neutral at best.
What does "harmful or neutral" have to do with the amount of information? Is there "information" on the television news? Is it all cheerful happy stuff, or do plane crashes count as information also?
Does a village in Burkina Faso whose inhabitants have two genetically specified varieties of hemoglobin in their blood have less, more or the same amount of genetic "informational content" as the neighboring village that has only one variety?

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Coragyps
Member (Idle past 845 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 89 of 104 (335518)
07-26-2006 4:41 PM
Reply to: Message 83 by MurkyWaters
07-26-2006 1:16 AM


Re: here we go ...
How else can you account for the fact that an abondoned plane left there just a few years earlier was found miles under the ice?
268 feet of ice, perhaps? And fifty years? In an actively flowing Greenland glacier in the snowiest part of the island?
The Lost Squadron (1932) — Pre-Code Hollywood Gem
Edited by Coragyps, : No reason given.

This message is a reply to:
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