[BMCDA]

Before I call this merely speculation, can you offer up a real life example of this phenomena? Certainly after all this time, there would still be some real examples of this.

Apparently you didn't pay attention but he did. Here is a website with additional information on ring species, especially on the already mentioned greenish warbler and the ensatina salamander.

[BMCDA]

More links are at the bottom of the page.

[connectthedots]

In Siberia, two distinct forms of greenish warblers coexist, one in the west and one in the east, their distributions narrowly overlapping in central Siberia, where they do not interbreed. These forms differ in color patterns, the songs that males sing to attract mates, and genetic characteristics. Also, males of each form usually do not recognize the song of the other form, but respond strongly to their own.

That's like saying a woman and man from different continents, cultures, religions, and languages are different species. They are the same species, and have variations within the species. It does not mean they can't mate.

That is just one example of the faulty logic. Needless to say, I am unimpressed.