23F BISC208 –
Week 9 (Ex. 11) Predator-Prey Ecology Instructions: Type your answers directly into this document and change the color or bold the text to make your answers stand out
. Save your assignment as a PDF and submit it to the appropriate assignment on Canvas, due by 11:59pm, the day after your lab meets. Double check your submission to ensure you uploaded the correct, complete file to the Canvas assignment. You can resubmit the assignment if needed, though the late penalty will apply if you submit after the due date/time.
Reflect on what you learned about predator-prey ecology in the Isle Royal lab. You may discuss these questions with your partner, but be sure to write the answers in your own words. Questions:
1.
The carrying capacity for moose on Isle Royale is 400. a.
What determines the carrying capacity for moose? (0.5 pt)
i.
Rate of plant growth b.
Fifty more moose arrive on the island. Immediately upon their arrival, does the carrying capacity increase, decrease, or remain the same? Briefly explain your answer. (0.5 pt)
i.
The moose population grows very rapidly when moose first arrive on the island because plants are so abundant. The rapidly growing moose population experiences a round or two of reproduction that can't be supported by the rate of new plant production.
2.
When the moose initially arrive on the island, their population increases above the carrying capacity, then decreases and stabilizes around the carrying capacity. Why does the population increase above the carrying capacity, then decrease in this manner? (1 pt)
a.
As population size approaches the carrying capacity of the environment, the intensity of density-
dependent factors increases. For example, competition for resources, predation, and rates of infection increase with population density and can eventually limit population size. 3.
What happens to the carrying capacity for moose when the wolves arrive on the island? Why? (1 pt)
a.
The carrying capacity did not change because the moose were limited by plant growth, which did not change with the introduction of the wolves. 4.
Describe the relationship between the cycling of moose and wolf populations. What does the population vs time graph look like? (1 pt)
a.
When moose are high, the wolves eat well and reproduce more. As this happens, the wolf population increases. The increase in wolves leads to more predation on moose, so the moose population drops. The graph had waves in it from when the wolves were thriving and then when the moose were thriving. 5.
How do the average fat stores in the moose population compare when wolves are present on the island versus when wolves are absent? Why does this difference in fat stores occur? (1.5 pts)
a.
When wolves are present on the island the fat storage in the moose is higher because the moose have to burn more calories trying to outrun the wolves and trying to survive. When wolves are absent the moose do not have to burn calories to survive as much.
