Amountain separates a population of mice into two distinct eastern and western populations. the eastern area is inhabited by owls, which hunt at night. no owls live in the western area. overtime, the eastern population of mice will most likely

Since owls live on the eastern side and not the western side, overtime the population of mice on the eastern area would diminish in numbers while the mice on the western side will increase and thrive in numbers ( since no owls are hunting them ).

Regular or uniform type