I just want to second the point raised about this being factually incorrect. Populations don’t evolve on a trajectory, except in our own minds and in hindsight. Some human population, if they remained isolated long enough, could become subspecies, but there is no way of saying “X” group of people are “on their way” to becoming a subspecies since there is no way of knowing that they are “on their way” to becoming an isolated breeding population.
But if Canis familiaris occurred separately, more than once–dogs from one geographical area are thought to have evolved from one subspecies of wolf, while dogs from another, from another–then even “subspecies” is patently inaccurate. You can’t have an evolutionary branch diversify, and then re-converge, in different geographical locations. The fact that the different branches evolved into the same species makes it impossible that they detoured into subspecies along the way. It just doesn’t work that way.
Note the word “PERHAPS”. It was a conjecture. Those were just a list of isolated populations. I am not going to debate Homo Sapiens here anymore however, as it seems dudes find it hard to be objective- and I understand that. It’s an interesting GD thread if someone wants to start it, but not here.
Lissener- well, but we don’t know that CF developed seperately. But you’re wrong- a subspecies can interbreed with other sub-species. " A taxonomic subdivision of a species consisting of an interbreeding, usually geographically isolated population of organisms.". If those populations come back into contact, and begin breeding again, then the “sub” part can stop. Now, if we were talking about a Species, then- in theory, no. But the line between Species, Subspecies and just plain populations is rather fuzzy and there are no exact definitions. Certainly by some defintions, all three Canis Spp are the same species. But by others, they are subspecies, or different species. The debate rages on.
Like with Neanderthal man- Species? Subspecies? I* think* that the *current opinion *weighs in that “Homo Sapiens Neanderthalensis” is correct, but we really don’t know for sure, and the issue is also clouded by the fact we are perhaps too close to them to be subjective.
[QUOTE=DrDeth]
Lissener- well, but we don’t know that CF developed seperately. But you’re wrong- a subspecies can interbreed with other sub-species.
I’m not talking about breeding; I’m talking about taxonomy. I’m saying that according to standard taxonomy, C.f. “appeared” separately in Asia, in Africa, and in Europe. That they speciated AFTER the parent populations became isolated from each other.
These populations didn’t come back into contact–I may have been unclear, although I tried to choose my language very carefully to indicate that I was not talking about separated populations coming back into breeding contact.
None of what you’ve said is new to me; in fact it supports exactly what I’m saying. Try again to see through my unclearness, if you think it’s worth the effort.
Even as conjecture your statement makes no sense. No population is on it’s way to becoming a subspecies. There is no “way”, no trajectory.
As I said ealier, the majority view is Homo neanderthalensis, not Homo sapiens neanderthalensis. The majority of the evidence today is that there was little to no interbreeding between Sapiens and Neanderthals, and that the split in the two lineages occurred about 500,000 years ago. This is the main justificaiton for the two species school of thought. Even if they could interbreed, they probably didn’t, hence two rather than one species.
But, as Dawkins likes to say, these discussions are pretty meaningless even concerning extant populations, much less when we’re discussing extinct populations. It really just depends on whether you’re a lumper or a splitter.
Oh I see.
You mean perhaps as in “There is no evidence for it, a lot of evidence against it, no convincing mechanism as to how it could have occurred, but it isn’t actually ruled out by the laws of physics?”
So you mean perhaps they were on their way to becoming separate subspecies in exactly the same way I might say “Perhaps the moon landings were faked” or “Perhaps evolution is a conspiracy”.
No they were not. When exactly have pygmies ever been isolated? When have Ainu ever been isolated? In the last 120, 000 years when have members of those groups or their ancestors ever been isloated for more than 6 months?
IOW we have asked for evidence for your claims and shown that they can’t be accurate so you are backing down. That’s good. And admission that you were making it up would be better.
Sorry, missed this–
No, we know that CF did NOT develop separately; that was my point. Because that’s not how speciation works. But the only way to accept the standard taxonomy of *Canis *is to overlook that, and to believe that it did.
Now, my cite for this may not be all that compelling: I read it an extremely long and detailed and fascinating article about dogs first published in the Atlantic Monthly like 15 years ago. I was a dog trainer at the time. Googling now, I find some evidence that more recent DNA technology suggests a common ancestor for all modern dogs, rather than the branching-before-speciation model that existed 15 years ago.
So now I’m not so sure. If I get a chance I’ll see if I can track down something more substantial . . . if anyone is interested in this particular hijack, that is.
I think he means that we don’t kow dogs derive from more than one local population of wolves. I’ve seen recent genetic studies that indicate all domestic dogs are descended from one local population of wolves in Central Asia, but I’m not sure there is a consensus among biologists about that.
Not that your point isn’t well taken that *Canis *is a rather odd genus, what with several very closely related species (including coyotes, which mate with wolves fairly often in the wild).
I agree with this, too. I think that it’s quite fair to call coyotes and wolves seperate species - there are so many differences in the patterns of behavior between the two, after all. But I can’t say that lissener’s point is without its own merits.
What definition would that be? I am not aware of any taxonomy that would say that Canis lupus and Canis latrans belong in the same species. All species of *Canis * are believed to produce fertile hybrids. If producing fertile hybrids were the standard for defining species, all wolves, coyotes, dogs, and jackals would be a single species. So would most species of ducks in the genus Anas such as Mallards, Black Ducks, etc.
This reference indicates that the dog lineage split from the wolf lineage a long time ago, but that there have been frequent back-crosses with wolf populations from different areas.
See the article cited above; the dog lineage branched off from that of wolves, but did not “speciate.” Backcrosses have taken place; dog evolution has essentially been reticulate rather than having a simple dichotomous branching pattern.
“Standard taxonomy” for domestic dogs at present generally regards them as belonging to Canis lupus, not Canis familiaris. The tendency today is to classify domestic animals as belonging to the same species as the ancestral type; in the past they were often classified as separate species. The problem is that the Biological Species Concept defines species on the basis of what happens in nature; therefore it cannot be rigorously applied to domestic animals.
Speciation is not necessarily a smooth process. Populations can become isolated, develop differences, then come together again and interbreed once more to a greater or lesser extent. Many subspecies have their origin in this kind of an event. (The Phylogenetic Species Concept would regard many such “subspecies” as good species, in contrast to the Biological Species Concept.)
However, some species may develop differences across their ranges due to different selective forces without ever having been split into different isolated populations. Such gradual variation across a species range is called clinal variation. In the past, subspecies were often defined on such clinal characteristics; the tendency today is not to recognize subspecies in such cases. Human variation is essentially clinal; therefore there is no reason to regard human “races” as subspecies or incipient species.