Dehammer said:
1)man has not allowed them to expand beyond a certain boundary
Not the case at all. This sort of limitation would be impossible to effect. In fact, man has tried with limited success to greatly expand the range of all three species through introduction of both wild-caught and captive-raised individuals. The introductions are either successful or not, based on the ability of the species to adjust to local conditions. In no case has any of the three species been able to colonise territory that is dissimilar to their native range in the eastern hemisphere.
What, for instance, stops the gray (Hungarian) partridge from moving south into central/southern Nebraska and Kansas? For some reason, after dozens of generations, the species has been unable to expand southward. Why no adaptation?
2) evolution takes time. it does not occur in one generation (save as the result of something like a major virus attack, which i don't believe has ever happen, or the intentional intervention of a scientist, which is likely still beyond their capacity), or even several. it takes dozens of generations for even small change to affect a large part of the population.
Understood. However, all three species have been here (the western hemisphere) for dozens of generations. In the case of the ringneck, over 100 generations.
3) moving into a new area is not evolution. its territorial migrations. that usually only occurs when the old territory is too small for the population, which in this case hunters have seen to it not happening, or it becomes to dangerous to remain. since hunting only occurs during a small part of the year, and is only allowed for the hunting of males, its not felt to be that dangerous for the species.
Right, but my point was that if these species are adapting (why wouldn't they in a world of evolution) why are they unable of themselves to colonize territory over that of their original territorial expansion?
What has happened in the case of all three is that, once released into acceptable habitat, they expand rather quickly to inhabit all of the contiguous territory that meets their habitat needs. Something of a population explosion. Then predation steps up to the challenge, "discovers" the new species, and the population dynamics of all concerned organisms adjust and adapt to the new situation. Eventually, population equilibrium is reached within a few generations, and the new species becomes subject to the regular population swings that we see in nature.
Hunters, by the way, account for a small fraction of the population in any given year. It is true that hunting is limited to males only for ringneck pheasants, but the partridges do not offer the degree of sexual dimorphism that would allow for quick sexual identity as required in a hunting situation. In addition, the partridges are generally monogamous, so hunting males exclusively would be counter-productive.
