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Author | Topic: intelligent design, right and wrong | |||||||||||||||||||||||
PaulK Member Posts: 17822 Joined: Member Rating: 2.2 |
The simple answer is that taxonomy is not cut-and-dried and there is eternal warfare between the "lumpers" and the "splitters".
So while dogs could be considered a non-geographical "ring species" by the "rules" (which in reality are treated more like guidelines if you ask me) it isn't very likely that anyone will propose that the dog species is split, let alone getting it past the committees that decide such things. To point to just one example working the other way, the European White-headed Duck (Oxyura leucocophala - mainly found in Spain) and the North Americal Ruddy Duck (Oxyura jamaicensis - introduced into Britain), are considered different species. That hasn't stopped the British Ruddies hopping over to Spain and having their wicked way with the Senoritas, to the point where it is considered a significant threat to the already-endangered White-headed duck species.
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biglfty Inactive Member |
Is there some reason you are ignoring my posts and restating the same error you made initially?
my apologies, i actually wanted crashfrog to answer becuase is was his argument that wasnt making sense. [This message has been edited by biglfty, 05-28-2003]
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lpetrich Inactive Member |
It is certainly true that our species is almost certainly not descended from any present-day ape species. However, the common ancestor would have been very simian, and very worthy of the title "ape".
And fossil hominids show show lots of intermediate features. So this is a bit like quibbling over whether dogs are really descended from wolves. And on the subject of dogs, the sequencing of their genome will get started in a few months, according to this article. Boxer dogs are the first to be sequenced, because they are relatively inbred, resulting in smaller amounts of confusion from polymorphisms. And when they are done, about a year from now, then 10 - 20 other breeds of dogs will have their genomes probed. It will be interesting to locate the genes that make a Great Dane so much bigger than a Chihuahua -- which are likely to be a very tiny fraction of the genome.
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Quetzal Member (Idle past 5872 days) Posts: 3228 Joined: |
This is getting interesting.
You're not incorrect when you state that gene flow connects all the breeds of dogs. My guess would be that this is one of the key reasons why nobody's bothered to try and split dogs into separate species. That and the fact that the various kennel clubs would be up in arms immediately. You're not entirely correct, however, either. Let me try and clarify. If we look at the various breeds of dogs as distinct populations, and the generic "dog" as a metapopulation, it's pretty easy to tell that the extremes (great dane and chihuahua) are clearly connected by a chain of intermediate populations. If we lined up all these dog populations in order from smallest to largest, there is no question that adjacent populations would be able to freely interbreed (all other things being equal). Hence, there is gene flow from one end of the chain to the other. IOW great danes have chihuahua genes and vice versa, even though they likely couldn't mate directly. To borrow a creationist expression, "they're all still dogs". However, and here's where it gets a bit sticky, when the degree of gene flow between two populations becomes "insignificant", they can justifiably be claimed to represent distinct species if the divergence between them is great enough. The trick, of course, is to determine when "significant" becomes "insignificant" (i.e., where to draw the line). As with so much of nature, the problem really defies crystal clear definition. If all our populations of the metapopulation "dog" were bent around in a huge circle where the great danes ended up standing next to chihuahuas, and given the rather obvious pre-zygotic barrier between them, any "splitter" taxonomist encountering them would be justified in claiming they were distinct species. Even if our taxonomist could trace the relationship through all our intermediate dog populations, s/he could still argue the case that the degree of gene flow between our extreme populations was "insignificant", and hence still claim distinct species. A purist "lumper", OTOH, would counter that unless there was a break in the chain (i.e., a disruption of the gene flow between the populations through extinction of an intermediate form or population or whatever), there would be no justification for proclaiming great danes and chihuahuas different species. A hypothetical paleontologist from the far future comparing the fossils of both would definitely conclude that s/he had related but "no doubt" distinct species (or possibly even genera). Just to make things even more complicated, there are examples where interruption of gene flow ISN'T required for speciation. Irwin, DE, 2002 "Phylogeographic breaks without geographic barriers to gene flow", Evolution, 56(12):2383—2394 quote: Irwin has another article, on-line, that explains in great detail the issue of gene flow and ring species: Ring species as bridges between microevolution and speciation. Let me know if the above actually made any sense to anyone.
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crashfrog Member (Idle past 1467 days) Posts: 19762 From: Silver Spring, MD Joined: |
i actually wanted crashfrog to answer becuase is was his argument that wasnt making sense. Sorry about that; let me try again. The reason there's no "ape-men" is because there's nothing that could be between humans and apes. Apes end where humans begin, but we're all still primates. Another way to look at it could be, imagine future humans some 10,000 years in the future - to them, we're the ape-men, because we're between primates and what they consider "human".
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Peter Member (Idle past 1479 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
I opened a thread on intelligence behind design,
where I suggested that the output of an evolutionary process would look like a 'designed system'. Partly the idea stems from genetic algorithms used todesign electrical circuits. If design does not require 'intelligence' nor a 'designer'then evidence of design cannot be used to infer anything.
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mark24 Member (Idle past 5196 days) Posts: 3857 From: UK Joined: |
Quetzal,
quote: It did, but for clarification, are we saying that the phylogeographical breaks were once actually indicative of an actual geographical barrier to gene flow, now no longer present? ie one species expands its geographical range around both sides of a mountain range, by the time the two populations meet at the other side they are different enough to either have actually speciated, or differ enough that mate selection reduces gene flow across the zone? Thanks, Mark ------------------Occam's razor is not for shaving with.
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Quetzal Member (Idle past 5872 days) Posts: 3228 Joined: |
Not always. This was Mayr's (and others, although Mayr called it something else) original definition, and it's a pretty good one. However, the point of Irwin's article, for example, was that reproductive isolation (phylogeographical breaks - a really stupid term IMO) between populations can arise that AREN'T relatable to interrupted gene flow - i.e., no physical geographic separation. We also see this in species flocks, and some of the other examples of what amounts to sympatric speciation. OTOH, the Ensatina complex DOES appear to have been caused by just that mechanism.
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Adminnemooseus Administrator Posts: 3974 Joined: |
Once again we have that clumsy situation of a (IMO) very nice, but off-topic discussion happening (this is in the "Intelligent Design" forum). As such, it is subject to getting lost, as far a future reference.
I think we need to continue the speciation line of discussion at either Species emergence ... or Definition of Species, and leave this topic string to the intended subject. Adminnemooseus
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mark24 Member (Idle past 5196 days) Posts: 3857 From: UK Joined: |
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Quetzal Member (Idle past 5872 days) Posts: 3228 Joined: |
Sorry, moose. Won't happen again (yeah, right. )
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Peter Member (Idle past 1479 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
Is this thread kinda off-track and dead ... or is it
just me?
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MrHambre Member (Idle past 1393 days) Posts: 1495 From: Framingham, MA, USA Joined: |
I think things were getting interesting when people were trying to compare and contrast creationism and IDC.
I'm very suspicious of attempts to separate IDC from standard creationism, and I'm even reluctant to refer to "Intelligent Design" without adding "Creationism," although I'm sure that's not a designation that proponents of IDC prefer. Dembski himself objected to the way Robert Pennock consistently uses the 'IDC' tag. Needless to say, that's a good enough reason for me to adopt it as well. However, the IDC'ers should be careful to what extent they declare IDC has diverged from the original creationist population. After all, the main thrust of IDC is identical to standard creationism: casting doubt upon the Darwinist scientific orthodoxy. The end result of this strategy is supposed to be the downfall of naturalist, materialist, reductionist science. Here's the problem: what replaces it? IDC's insistence that it is a different philosophical entity from standard creationism is a double-edged sword, it seems. Though it would allow IDC to distance itself from religious fundamentalism and biblical literalism, it would also make explicit the fact that no one philosophy could claim to replace Darwinism by default. This would force IDC to create a more positive account of its methodology, something that does not seem forthcoming.
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Peter Member (Idle past 1479 days) Posts: 2161 From: Cambridgeshire, UK. Joined: |
The OP suggested that without 'Intelligent Design' there
could be no right and wrong and we may as well kill someone as eat an icecream. That's what I meant by off-topic.
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MrHambre Member (Idle past 1393 days) Posts: 1495 From: Framingham, MA, USA Joined: |
I'd rather eat an ice cream.
Are we back on topic now?
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