Rock Pocket Mouse (Bee) Evolution Activity-3

How Can Evolution Be Observed in Mouse Populations? ~ 45 minutes A typical rock pocket mouse is about 170 millimeters long from its nose to the end of its tail, shorter than an average pencil. And at just 15 grams, this tiny mouse weighs about as much as a handful of paper clips. You can find populations of rock pocket mice all over the Sonoran Desert in the southwestern United States. There are two common varieties, or phenotypes—a light-colored variety and a dark-colored variety. There are also two major colors of substrate, or surface materials, that make up the desert floor. Most of the landscape consists of lightcolored sand and rock, but patches of dark volcanic rocks that formed from cooling lava flows are found, separated by several kilometers of light colored substrate. Activity 1 1. View the images of the rock pocket mouse populations in each location and record the numbers for each color. Each location should have 12 mice. Card 1 Location A: Number of mice with light-colored fur 12 Dark-colored fur 1 Location B: Number of mice with light-colored fur 10 Dark-colored fur 2 Card 2 Location A: Number of mice with light-colored fur 10 Dark-colored fur 2 Location B: Number of mice with light-colored fur 10 Dark-colored fur 2 Location A: Number of mice with light-colored fur 10 Dark-colored fur 2 Card 3 Location B: Number of mice with light-colored fur 6 Dark-colored fur 6 Card 4 Location A: Number of mice with light-colored fur 11 Location B: Number of mice with light-colored fur 9 Dark-colored fur 1 Dark-colored fur 3 2. Arrange the cards in what you think is the correct order from the oldest to the most recent. Write the order you chose: 4, 3, 1, 2 3. What are the two types of substrates that these mice live on? It seems as if the mouse live on different colors of rocky land or it could be a composure of the light ground being sand and the dark being dirt. 4. What are the two phenotypes found in these mice? The obvious difference in phenotypes of the two mice are one being a blond like color and the other a chocolate brown. 5. Suggest a reason for the differences in mice in those two areas: The reason for the difference in the mice’s color is because they adapt to which ever color conceals them the best to hide from predators. Activity 2: Watch the video at biol.co/rockpock and answer the questions. B 1. What caused the unusual landscape at the Valley of Fire? a. flooding b. volcanic eruptions c. human activities d. forest fires C 2. Predators of the pocket mice hunt using what sense? a. smell c. vision b. sound d. heat B 3. Why did dark-colored rock pocket mice first appear in a population of light-colored rock pocket mice? a. Individuals change color to blend in with the environment. b. There is dark lava rock in the area where they live. c. They have a genetic mutation that affects their fur color. d. Predators eat light-colored rock pocket mice. A 4. Why do dark-colored rock pocket mice on dark lava flows have white bellies? a. There is no selection for dark bellies by visual predators. b. White bellies protect them from insects found in the desert c. There is a reproductive advantage to having a dark belly. d. White bellies are an important part of camouflage. D 5. Mutations can be: a. good b. bad c. neutral d. all of these A 6. Dark pocket mice are found in locations that have dark substrate. Genetics revealed what surprising fact about mice in different locations? a. they had different mutations b. they had the same mutations c. they were not related 7. Now that you have watched the video, go back to your set of cards and arrange them in the order you think they happened, starting with the oldest. You may change your order from your original idea. What is your final order? 4, 3, 1, 2 8. Explain how you decided on the final sequence. I stand with my first order in the cards because my original thought process was that evolution is about mutations being able to evolve an animal to where they will be able to survive better. Therefore, by choosing the cards to the least dark mice to the most I followed the theory of evolution and was assured with the order when watching the video. Answer True or False to the following statements about rock pocket mice: T 9. More dark mice will be found on the lava rocks than light colored mice. F 10. Dark mice are more likely to survive on sandy substrate. F 11. Mice can choose to be dark or light. T 12. Dark coloration is a result of a gene mutation. T 13. A light mouse is likely to move to a sandy area. T 14. Selection occurs when predators kill mice that are not suited to their environment. T 15. There is more than one mutation that can affect coloration in mice. Activity 3: Data Analysis ~15 minutes Use colored pencils to make a BAR GRAPH showing the numbers and colors of mice at each location. Each period will have two bars, one for light and one for dark mice. Use a dark color for dark mice and a light color for light mice. Analysis - Answer each question with complete sentences. 1. Compare how the graph looks at Location A to how it looks at Location B. What happened to light colored mice at location A? The light-colored mice at location A thrive because it is based in a light-colored substrate. What happened to light colored mice at location B? The light-colored mice at location B reduce everywhere except for card 4 (light colored substrate) because they are in a dark colored substrate. 2. Remember that “fitness” is defined by an organism’s ability to survive and produce offspring. Explain why a rock pocket mouse color influences its overall fitness. A rock pocket mouse color influences its overall fitness because its ability to blend in with its environment protects it from any predator. As seen by the graphs light pocket mouses survive better and location A than B because of their environment canceling them. 3. Explain the presence of dark-colored mice at location A. Why is this phenotype (appearance) not more common in the population at that location? Dark colored mice at location A are less common because they are not as visible to predators and stand out against the environment. VIDA Chart- In the evidence section, write a list of ways in which the rock Evolution by Natural Selection pocket mouse illustrates the idea posed in the description. Use what you have learned in the activity and the film we watched on rock pocket mice. ~ 5-10 min Condition Variation Description Evidence from Species Studied Individuals in a population differ in The rock pocket mouse has a sandy and some trait. dark color within the population due to gene mutation proving the idea of Variations can be physical Variation. features, behavior, bodily functions, or resistance to disease. Inheritance The trait is inherited (passed from parents to offspring). Differential More offspring are born than can survive. Survival and Reproduction The rock pocket mouse mutated and changed over time due to natural selection and sexual reproduction leading to the The variation comes from random different variations of the offspring proving mutations and recombination of genes during sexual reproduction. the idea of inheritance. In the rock pocket mouse population, there was an increase in dark mice and less sandy ones because the dark were Some individuals with a trait are eventually the ones to most likely survive, more likely to survive and reproduce than those without the proving the idea of differential survival and reproduction. trait. Selection depends on the environment. Traits that are beneficial in one environment may not be beneficial in another. Adaptation The frequency of the trait that helps individuals survive or leave more offspring will increase in the population over time, as will the alleles that affect the trait. This process can take many generations and extend over very long periods of time. The rocket pocket mouse has proven the condition of adaptation because they had to adapt to their different types of substrates to blend in and survive against predators.