Foxy {L_WROTE}: So Nancy, you are saying that all 'wild' boar in HK are feral pigs i.e. domesticated, selectively bred pigs that have gone wild and reverted to a 'wild' morphology. What evolutionary pressures would drive this reversion to a wild phenotype and how long are we talking about here? When I studied Darwinian evolution, I understood that it was a very slow process indeed.
That is correct; "wild boar" in HK are feral pigs. I think that some of the change in phenotype, such as the muscular build of wild pigs, has simply to do with going from lounging around and eating a lot as a pet or food pig to actually having to ensure their own survival. They probably find a lot less to eat, rooting on their own, and get a lot more exercise than when in captivity. I am not sure about the tusks in males, as I am certainly no pig expert. I suspect non-breeding pigs are neutered and the loss of testosterone may inhibit growth of tusks in captive pigs or maybe they don't have them at all. Loss of testosterone probably prevents the muscular build of the shoulders that wild pigs have. This I don't know for sure, though. I tried to find out how many generations are required before the wild phenotype emerges but my best evolution reference book is at the university. I will let you know if I find out; I am curious myself about this.
Yes, when I took evolution in college many years ago I learned the same - that evolutionary processes took thousands, if not hundreds of thousands of years. We are now finding that for many species, especially those with exponential growth rates (i.e. bacteria and some other organisms) and/or short generation times, that selection can occur within several generations. A few studies of amphibians have shown that adaptation (selection) has occured within about 40 years in response to habitat change, which amounts to about 8-12 generations for the particular species studied.
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