Evolution by Natural Selection

*** Please review lesson 5.02 to help answer the questions

Living things that are well adapted to their environment survive and reproduce. Those that are not well adapted don’t survive and reproduce. Any inherited trait that increases an organism’s ability to survive is called an adaptation. Remember that these adaptations are inherited traits; they are not changes that an individual chooses to make and that increases fitness, which is defined as the ability to survive and reproduce.

Natural selection is a mechanism for the evolution of a population to become better adapted to their local environment over many generations. As we explore how natural selection works, pay attention some of its main principles: variation, overpopulation, adaptation, and descent with modifications.

The figure above depicts a 3 month time span that occurred.

Step 1: Use the figure above and predict how many mice will survive in months 5 – 7 using the table below.

Mouse type / Month 1 / Month 2 / Month 3***
White / # of mice = 4 / # of mice = 3 / # of mice = 1
Gray / # of mice = 4 / # of mice = 4 / # of mice = 4

My Predictions:

Mouse type / Month 4 / Month 5 / Month 6*** / Month 7
White / # of mice = 4 / # of mice = / # of mice = / # of mice =
Gray / # of mice = 16 / # of mice = / # of mice = / # of mice =

*** Mice, reproduce once every 3 months, with each mouse having 3 off spring – so reproduction will be occur in month 3 and month 6.

Example: In month 3, 1 white mouse survived and 4 gray mice survived. If each have 3 offspring, then in month 4 there would be 4 white mice (1 parent + 3 offspring = 4 total) and 16 gray mice (4 parents + 12 offspring = 16 total). Using this formula and based on your predictions, this will help you predict the total number of mice in Month 7 after they reproduce.

Step 2: Create a graph that represents the # of mice from months 1-7.

Step 3: Answer the following reflection questions.

1.  How do the original and surviving prey populations compare from month 1 and month 3?

2.  How did the colors of each type of prey affect its population size over time?

3.  What color seemed to camouflage the best in this habitat? What color seemed to stand out the most?

4.  How might these results change if there were black mice were present in the environment?

5.  What traits could help a predator be more “fit” in this model environment?

6.  Describe other adaptations besides color that could affect the survival of an individual (prey).

Step 4: Upload your graph and completed analysis report for grading.