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Originally Posted by Diablo
Jeff, you are incorrect in thinking that they are all within the same species. Of the 14 finches, they are all a different species, and they span 6 different genuses.
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There are (and have been) many definitions of species and I'm not a taxonomist, so I'll accept that the are not the same species according to the current taxonomic definitions. That said, my point, that they are all still finches, still stands. They are not crows or doves or anything else.
In one, long standing, definition of species (the biological definition), it is stated that a species is any group of individuals that do not successfully interbreed with other groups. All "dogs" (of the genus Canus) can successfully interbreed (although they don't choose to), therefore one could say that based on this definition that all dogs are in the same species. Similarly, all of the finches (reportedly) can (and do) indeed successfully interbreed. As such, at least by this definition (by biology), they may be considered the same species.
One of the problems is that species can mean so many things. The taxonomist would tell you that the fourteen "species" of finches are different, yet at the chromosome layer, they are completely compatible and thus biologically, they can be considered the same, just expressing variation. Of course some scientists wouldn't agree with this (because it hurts their arguments, especially related to evolution), and yet by definition, most do admit this. So is species a taxonomic issue or a biological one? I tend to lead towards the biological as the true determinant (because that is what evolution is all about, isn't it?).
-- Jeff