Evolutionary Theory Explains Diversity

How many times is it necessary to debunk this sort of misguided nonsense before creationists finally stop posting it. In fact, Darwin didn't study the finches. He collected a few and brought them back to England. The analysis of the specimens was done by Richard Owen, who actually discarded Darwin's specimens because he failed to sufficiently document the circumstances of their collection. Captain Fitzroy did a better job. Owen surprised Darwin by pointing out that there were several species represented.Well, guess what. Only three species of Darwin's finches have ever been observed to interbreed. In those cases it was Geospiza fortis that interbred with G. scandens and G. fulginesa. Those species are closely related and are, respectively, the medium ground finch, the cactus finch, and the small ground finch. It is no more surprising than the interbreeding of the eastern and western meadowlark, and way less surprising that the interbreeding of the brown bear with the polar bear.It is deceptive to state without qualification that Darwin's finches interbreed when, in fact, only three closely related species have ever been observed to do so, and then it was in a case of extreme low population density due to a severe drought. Mates of the appropriate species were difficult to find. Thus, hybridization between closely related species took place. During normal years with higher population densities, it never occurred.If one understands evolutionary theory, the hybridization between closely related species is not surprising. Hybridization of two species of watermelons (i.e., diploid and tetraploid species) produce a triploid species. Strange as it may seem, seeds from this cross must be fertilized by the diploid species to produce fruit without seeds.

Do you have any evidence of a "kind?" It's funny that you should choose dogs as an example of this variation. On the rare occasion that a biologist makes a distinction between micro-evolution and macro-evolution, he defines the former as variation below the level of species, and the latter as variation at or above the level of species. So you claim that all dogs are the same species, and yet, the family canidae (dogs) contains 14 genera and 36 species. If you wish to limit "dogs" to the genus Canis as creationists invariably do, then there are 7 species. Three of those species, C. latrans, C. lupus, and C. rufus are able to interbreed, which shows that there must be common ancestry. Or, you may wish to limit "dogs" to a particular species, as creationists invariably do. That would mean that dogs are C. lupus, wolves. That has been shown to be true by genetic sequencing. And yet many dogs can still interbreed with wolves as well as C. latrans and C. rufus. On the other hand, if dogs were not domestic animals that are lumped into one non-taxonomic group, they would be classified as several species. You see, while many dogs can and will interbreed, interbreeding is impossible for some varieties, even artificially. In many cases, the offspring are aborted before reaching term. So it seems that dogs have become several different "kinds."

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You see, while many dogs can and will interbreed, interbreeding is impossible for some varieties, even artificially. In many cases, the offspring are aborted before reaching term. So it seems that dogs have become several different "kinds."
  —pandion

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Sorry, I can't. I don't know if this information is on the Internet. I actually was informed of this by a D.V.M. The examples he gave were a Great Dane or a St. Bernard with a chihuahua. Natural interbreeding is impossible no matter which is male and which is female. Even if artificial crosses are made, the fetus is aborted, still born, or the mother dies during gestation.Of course, it really doesn't matter if chihuahuas can breed with terriers, and terriers can breed with larger dogs, and those with even larger dogs all the way up to a St. Bernard or Great Dane. According to the Biological Species Concept, chihuahuas and St. Bernards are separate species, not only because they don't interbreed but because they can't. Lions and tigers not only can interbreed, they will. The same is true of Polar bears and Grizzlies.Edited by pandion, : No reason given.

I've looked into it on the web as much as I could. I did find lots of people who have a cousin or know someone who heard that Chihuahuas and Great Danes did, in fact, interbreed. I guess, when it comes right down to it, their references are about as reliable as mine, since mine are really nothing more than "I heard from someone..." Personally, I am skeptical of unreasonable claims while I am inclined to provisionally accept statements of knowledge about reasonable events from a knowledgeable source. But I understand that you don't know me or my Vet, so I can understand your skepticism about something that you probably haven't ever considered before. But I'm going to be seeing the Vet next week and if I have the opportunity, I'll ask.But, when it comes right down to it, you've got to admit that a Great Dane (m) x Chihuahua (f) is highly unlikely. And, in spite of what some poster's cousin has heard, a Chihuahua (m) x Great Dane (f) seems equally unlikely. Things just don't match up, either way. I haven't been able to find any documented example of either cross happening naturally.When it comes to artificial crosses, I wonder why. Why would a breeder even attempt such a cross? Breeders are in the business to make money, and I can't believe that such a cross would actually be valuable. I even found a breeder on the web that breeds both Chihuahuas and Great Danes, and it apparently hasn't occurred to this breeder to cross the two.But given that natural crosses are so much more unlikely than crosses between tigers and lions or crosses between grizzly bears and polar bears, and that these are considered to be 4 species and not 2 with variation in kind, I think that the observation that Chihuahuas and Great Danes would be, in fact, classified as separate species, were it not for the fact that they are domestic animals, is reasonable. But the question is moot, since both breeds of dog are classified as Canis lupus domesticus anyway.You can be as skeptical as you want about their inability to interbreed. Personally, I'm skeptical about their ability to do so under any circumstances.

Of course they do. Dogs have also been known to interbreed with wolves, i.e., Canis lupus. Not surprising since DNA analysis has shown that domestic dogs are descended from Gray Wolves (C. lupus). Coyotes have also been observed to interbreed with Red Wolves C. rufus. In fact, in Texas, the animals now called "Red Wolves" are thought to be a hybrid population of C. rufus and C. latrans (Coyote). Red wolves, on the verge of extinction, selected whatever mates were available, even if they were coyotes. Red wolves only survived because they could interbreed with coyotes.But that's not the question. Gray Wolves, Red Wolves, Coyotes, and domestic dogs are 3 separate species and a subspecies of the first. They can interbreed. That's the biological facts. So a Great Dane and a Chihuahua are just variation in "kind" from the wolf "kind." They are, of course, all interfertile. You bet. Like a Gray Wolf would breed with, rather than eat, a Chihuahua.So what, exactly, is a "kind?"