"Please elaborate a bit more. Intra-population, or Inter-population dynamics?"
Both, but it's the inter-population dynamics which occassionally results in secundairy contact.
"I totally agree that to make a Gulf Hammock, you dont mix a yellow and a grey ratsnake. You need two Gulf Hammocks to do that. I'm not sure what you mean by that though, or why you chose that to illustrate your point."
You just did a fine job explaining a significant part of the point I was trying to make. It's kind of a long story, that's why I took a shortcut with the example of the Gulf Hammock Ratsnake. The thing is, when you breed two Gulf Hammocks, you'll get Gulf Hammocks. When you breed Grey to Yellow, you'll get a crossbreed only remotely similar to a Gulf Hammock, but not quite the same. When you breed these F1 crossbreeds together, you'll get lots of different stuff, but still no Gulf Hammocks. Bottom line: Intergrades breed true, man made crossbreeds don't. Why? Because natural selection gets to play an interesting role when secundairy contact becomes established. Some genes will be selected against, resulting in a sharp morphometrical cline, often positioned at a density through. Other genes on the other hand are neutral or will actually be favoured by natural selection, enabling it to introgress for hundreds of miles from one taxon into the other. The result is a more transient morphometrical cline, one taxon gradually transforming into the other, and vice versa. I believe the word intergrade actually refers to the morphometrical gradient associated with it.
"Also, if you could just clarify what you mean by Population Dynamics, I'm good on the Natural Selection part, or we should at least see reasonably closely eye to eye on that topic I hope."
Population Dynamics means a lot of things, including stuff like dispersal, mortality, reproduction rates, etc. In some cases, these parameters result in secundairy contact and intergradation. I think you get the picture. We're cool on the Natural Selection part.
"On that note.....here's a picture to keep things fun"
Good call. I was missing the fun part lately.