Deer go threw Natural Selection but not by the environment but by the female Deer. Female are going to want a deer that have the biggest antlers. So the ones that have the smaller antlers are not going to reproduces and will die off.
Hunters want a deer with bigger antlers so they are going to shoot the one with the digger antler. this could cause big antler deer to be selected out because they will be killed be for the can reproduce.