I have a question regarding evolution. Many things can happen which will cause genetic "direction" which will help insure the survival of a given species, correct? Warming climate, cooling, available food change (causing long neck in giraffes etc).
Now for the last hundreds of years, man has cultured pigs, which when raised by man in pens, survive under very different conditions than wild pigs. Granted, it's only been a few hundred years or so, but to my knowledge, wild and domestic pigs can still interbreed. From an evolutionary point of view, at what point does species differentiation happen? Will, at some point, half the offspring of one sow, not be able to breed anymore with wild pigs? I would think that at some point we will see this. In my case we breed shrimp for specific traits and this has been going on for 20 years or so. With shrimp, that's over 20 generations. Yet they still look the same and can breed with wild caught shrimp. Yet, at some point, we should see (maybe not in my lifetime) a point where a given isolated breeding population of pigs....or shrimp...can't breed anymore with the original parent stocks. Am I missing something here?