That's interesting about the change of fauna on the Wallace line. That makes one think of all of the bits and pieces of 'Pangaea' that fell off over the various millions of years, giving Australia different animals from the rest of the world and giving Tasmania even more different animals and flora. Same thing for Madagascar, which would imply that the islands have to be quite big for totally different animals to develop.
On the other hand, when places like Tahiti or Hawaii are mentioned, there do not appear to be the stunningly different flora and fauna of those other places -- possibly because too many people have passed through, whereas Madagascar and Tasmania are at 'the end of the line.'
The canals are man made. Sure there are gradual botanical and faunical changes but they really are gradual.
By the same token, there is a huge and sudden change in the fauna on this and that side of the Wallace line, right through eastern Indonesia. Nobody would say there's a continental divide there.
What about geologically, is there a divide between north and south America?
I'd agree Oceania is not a continent.
I don't think anyone has said the Panama Canal is a dividing line, but I did say the narrow "isthmus of Panama" divides the North and South continents of the Americas and I'll stand by that.
Also did you know that "continental divide" is a specific term that refers to an elevated line on either side of which water flows to opposite oceans? The Rocky Mountains and Andes form ccontinental divides, but no one is arguing for East and West America to be recognized as separate continents.
Actually, it is a slightly more civilised spammer based in Tamil Nadu. Since the person made the effort of actually writing a real post for once instead of all of the computer generated gibberish spam that we had in the past, I just removed the spam links and left the post.
(Usually all trace of the person is removed immediately.)