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Author Topic:   Imported weed diversification supports macro-evolution
Belfry
Member (Idle past 5203 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 12 of 59 (298125)
03-25-2006 7:12 PM
Reply to: Message 9 by kuresu
03-25-2006 5:08 PM


Breeds, speciation, and macroevolution
kuresu writes:
The only difference between Great Danes and Chihuahaua are which genes are expressed.
I don't think this is strictly true. Recent studies into the dog genome have found that the purebred lineages are genetically distinct from each other to a remarkable degree - with insertions, deletions, and sundry mutations accumulating easily in the isolated, inbred populations. The genetic differentiation between some dog breeds were found to be much greater than between isolated human populations on different continents, which is remarkable considering that most breeds have been created in the last 400 years or so. See this Parker et al. (2004) article in Science (link gets you the abstract, full text by subscription only - or see this NCBI article which talks about it).
Some people argue (and I'm inclined to agree) that Chihuahuas and great danes are anatomically incompatible enough that they would be reproductively isolated as "wild" populations, and could be thought of as different species.
More directly to the topic, the definition of "macroevolution" has been a source of much goalpost-shifting from the creationist side. Since speciation has been undeniably observed both in the lab and in the wild, the more experienced creationists no longer consider "mere speciation" to qualify as a macroevolutionary change, which many insist is somehow impossible. I say this to help explain Faith's reaction to your very fine OP.
This message has been edited by Belfry, 03-25-2006 07:13 PM

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 Message 9 by kuresu, posted 03-25-2006 5:08 PM kuresu has not replied

Replies to this message:
 Message 14 by mark24, posted 03-25-2006 7:59 PM Belfry has replied
 Message 16 by Coragyps, posted 03-25-2006 8:26 PM Belfry has not replied

  
Belfry
Member (Idle past 5203 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 17 of 59 (298132)
03-25-2006 8:29 PM
Reply to: Message 14 by mark24
03-25-2006 7:59 PM


Re: Breeds, speciation, and macroevolution
mark24 writes:
I'm not inclined to agree. Chihuahua & Great Dane genes are capable of gene flow, it might take a generation or two to get a Great Dane to breed with a smaller variety, & a Chihuahua with a larger & so on, but eventually, a Great Dane gene can easily get into a Chihuahua population & vice versa.
If individuals in a population can't directly interbreed, but can still pass on genes to decendents of those individuals, then under the biological species concept they are still a "good" species.
Those of us who work with plants find this species concept to be rather zoocentric! Animal examples such as "ring species" create problems for it, as well.
I was thinking after I posted that a better way to present it might be this: If alien biologists were to find an island populated by great danes and chihuahuas (with no dogs of intermediate size), they would be justified in regarding them as separate species.
I know, I know- Off topic, do not respond!!!

This message is a reply to:
 Message 14 by mark24, posted 03-25-2006 7:59 PM mark24 has replied

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