The correct answer to the question: How will this change in the environment most likely affect the mouse population, would be: According to the principles of Natural Selection, from Darwin´s theory, the mice with the thicker fur, given the new conditions in the environment, will be more likely to reproduce and pass on their genetic material to future generations, than those with thinner skin. The mice with thinner coats will start meeting a genetic dead-end, and most likely grow extinct as the environmental conditions change. These genetic changes, according to Darwin´s theory, will not be immediate, but will happen at a constant, increasing rate, through time, until the population left is the one that meets the necessary criteria given the demands of the environment.
Since most mice have thin fur, it is most likely a dominant trait. However, as the temperature decreases, the mice could adapt and their fur could become thicker.
