Final answer:
Trends in the mouse population over four years would likely show a shift toward smaller body sizes due to directional selection, with histograms illustrating this trend. Environmental factors, such as food supply changes, may also cause fluctuations in population size.
Step-by-step explanation:
When observing trends in mouse population dynamics over the course of four years, one must take into account various factors such as predation, food supply, environmental changes, and genetic variation. In the case presented, where larger body size makes mice more prone to predation, we would expect to see a shift in the population towards smaller body sizes over time due to directional selection. A histogram comparing body sizes over the four-year period would likely show a decrease in the number of larger mice and an increase in the number of smaller mice.
The concept of natural selection can be illustrated by changes in the population's body size distribution. The trend in the mice population, given a predator preference, would show that smaller mice have a selective advantage, which could be further substantiated by a histogram showing a skewed distribution favoring smaller sizes over time. If smaller mice are indeed surviving more often and reproducing, this would be a clear example of directional selection affecting the population due to predation pressures.
Another trend that could be observed might be related to changes in resources such as those caused by varying weather patterns. For instance, a mild winter leading to a boom in acorns could temporarily increase the mouse population, as observed with white-footed mice populations. Similarly, a decrease in resources like acorns during a harsher winter could lead to a subsequent decrease in the mouse population. These trends would be reflected in the number of individuals at different body sizes across the years.