Well...it depends on how you define law of nature.
Not really. I think it's fairly obvious that the distribution of different species of squirrel in North Wales is not determined by market forces.
Given than human demand for red squirrels is causing money to be spent to eradicate the introduced gray squirrel, I'd say that even that is not immune to market forces. Indeed, bounties have been paid for the tails of the pest in the past, tho that was abandoned as not providing sufficient control for the level of bounties that was being paid.