Kinda Biology 101, but if they mate and produce sterile offspring, there's no problem with their being species. Like lions and tigers, you know?
Sorry, I meant fertile off-spring, which of course is the opposite of what I wrote. And of course, this goes directly against Darwin's "Tree of Life".
Polyploidy is a difference in chromosome number; chromosome number differences are one of the major means of speciation
No, that's not what speciation is. That was my first problem with that site (Boxhorn's) is that he fails to give a concrete definition of speication. He sites Dobzhansky and then Mayer and he doesn't hold himself to either definition (and Mayer's is poorly defined anyway).
Specifically, Darwinists site a slow gradual change in the genetic code, whereas polyploidy is the result of a doubling (or occasionally tripling etc.) of the entire genetic code.
Owl_Eagle(If what I just wrote makes you sad or angry,
Actually no. Ring Species are a very good example of why the ability to reproduce is not the only criteria in determining where one species ends and another begins.
The concept of 'species' is a human construct used to order and classify life into neat little pigeon holes. Evolution predicts that the the concept of species will not be concrete but will be somewhat fluid - just like we observe.
Most of the extant species of American birds can hybridize and produce fertile offspring with at least one other species of bird. Mallards produce fertile hybrids with Pintails, Wigeon, European Wigeon, American Black Ducks, Mottled Ducks and a large number of other species. If your criterion of speciation were inabiility ever to produce fertile hybrids, there would be perhaps 4 species of duck on this continent. Orioles, warblers, etc are likewise mostly interfertile within the genuses. The major isolation mechanisms are geographical and behavioral, and when they break down, you get hybridization.
It's hardly surprising that the Darwin finches would do the same.
That was my first problem with that site (Boxhorn's) is that he fails to give a concrete definition of speication.