Final answer:
Populations of mice with different fur colors may experience changes in size due to natural selection, genetic drift, and the carrying capacity of the environment. Predators and camouflage are examples that can influence population dynamics.
Step-by-step explanation:
When considering populations of mice with different fur colors, various factors can impact whether the population size changes. Natural selection can play a significant role in these changes. Predators might more easily spot and capture mice with fur colors that don't blend into their surroundings, potentially leading to a decrease in the population of that fur color. Conversely, the population with a fur color that provides better camouflage may have an increased chance of survival and thus an increase in population size.
Genetic drift can also affect population changes, especially in small populations. If a random event disproportionately affects one fur color, it can lead to changes in frequency of the fur color trait, affecting the population dynamics. It's also worth noting that the carrying capacity of the environment, which is the maximum population size that the environment can sustainably support, will influence whether the population size increases, decreases, or remains the same.