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LAB 12

 

 

 

 

PART A

 

Activity 1: Predator Prey Coevolution

WATCH VIDEO & ANSWER QUESTIONS https://www.youtube.com/watch?v=NeCmSL_N65A

 

  1. What are some advantages to using sonar to find prey?
  2. What defense have some moths evolved in response to predation by bats?
  3. Of the nearly 140,000 moth species that exist, as many as half may be able to hear bat echolocation. When they hear the bat calls, some moths try to escape, while others produce ultrasounds in response. What are two ways in which ultrasound production can help moths avoid being eaten by bats?
  4. What strategy did the moths in Gorongosa use to escape bats. What pieces of evidence from the video support this claim?
  5. What does Dr. Barber mean when he says some of the moths are bluffing?
  6. Explain how the team tested if the moths were bluffing or not.
  7. According to the video how did these escape abilities originate in moths?
  8. Toward the end of the film, this statement appears in the video: “Coevolution: bats and moths reciprocally affect each other’s evolution;” Explain, in your own words, how each organism affects the other’s evolution.

Activity 2: Predator Prey Simulation

For this exercise we are going to use a simulation to model a single population of prey species: deer mice. Like all populations, the individual members are not genetically identical. The process of mutations arising throughout the evolutionary history of this species has created new genes, and sexual reproduction has shuffled those genes into new combinations. Those genes that are beneficial will accumulate in the population, while those that are harmful will not. This process is essentially natural selection.

We’re going to focus only on the gene that expresses coat color. Our mouse population has two versions of this gene: RD and RL. Individuals that have the genotype RDRD  will be dark brown in color. Those that are heterozygous RDRL  are medium brown, and those that have the genotype RLRL  will be light in color. We are going to investigate how predators and the physical environment in which the prey live influence which phenotypes are selected for (survive and reproduce) and which phenotypes are selected against (are eaten by hawks). The hawks are mainly visual predators, so we are assuming they are mainly picking mice based on their ability to see the mice.

 

  1. GO TO LINK http://short.concord.org/lm3
  2. Play around with the settings to see what everything does.
  3. When you’re ready, hit “reset”

To run the first simulation:

  1. Record the initial frequencies of each color of mice in the table below (this should remain the same throughout the simulation).
  2. Click the button that says “add” and has a picture of a hawk to add predators to the simulation. When this is turned on you will see hawks appear.
  3. Make sure the mutation setting is turned off (not checked).
  4. The environment should be set to field. Make a predication about which color of mice will be best at surviving in this environment in your notebook. 
  5. Click “run” and let the simulation go for 5 years (60 months).
  6. At the end of 60 months, record the final number of each mouse color in table 1 below under trial 1. In the tables below, L = light brown, M = medium, and D = dark brown.
  7. Click reset
  8. Repeat steps 1-7 for trials 2 and 3 for “field”
  9. Then calculate the average number of each color
    AVERAGE =
  10. Calculate the average percent for each color

AVERAGE PERCENT =X 100

  1. Repeat steps 1-9 with the “beach” environment (step 4).

 

 

 

 

 

 

 

Table 1: Population Data

Numbers of light and dark mice in the environment with hawks
Initial Frequency of Colors Environment Final Number of Mice in Population after 60 months (5 years)  

Average

Percent (%)

 
 

 

 

 

__% Light

 

__% Med.

 

__% Dark

 

  

 

 

Field

 Trial 1 Trial 2 Trial 3 Average
L L L L  
M M M M  
D D D D  
 

 

Beach

 Total Total Total Total  
L L L L  
M M M M  
D D D D  
Total Total Total Total  

 

 

 

After completing the simulations and calculating the values in table 1, answer the following questions in your notebook.

  1. In the prey population, which phenotype (color) was the most beneficial for each environment?
  2. In the prey population, which phenotype (color) was the least beneficial for each environment?

Does the fur color of the deer mice change over time when hawks are present?

  1. While we didn’t investigate evolution from the hawk’s perspective, propose one way the hawks may have also evolved over time as the mice coat colors changed.
  2. In evolutionary terms, what does “fitness” mean? It’s more than just the ability to survive!
  3. How does this simulation demonstrate natural selection and differential reproduction?

 

PART B

Activity 1: Keystone Species and Trophic Cascades

WATCH VIDEO https://www.youtube.com/watch?v=ysa5OBhXz-Q

 

After watching the video, answer the following questions in your lab notebook:

  1. Are all species present in equal numbers within a community? For example, do you think there would be equal numbers of elk and beavers in the Yellowstone community?
  2. Is every species prey to another in a community? Explain.
  3. Explain what impact the removal of wolves from Yellowstone had on the populations of elk.
  4. What indirect impact did the removal of wolves have on vegetation near the river bank in Yellowstone. Explain why this happened, even though wolves are carnivorous.
  5. After wolves were reintroduced to Yellowstone, explain what happened to the population of other species in the park. How did wolves cause this change?
  6. How were the wolves able to change the course of the rivers? Explain this connection.
  7. What do you think keeps the wolves from becoming overpopulated and eating all the elk? This isn’t in the video, you will need to use your thought sponge aka brain.