Essay type questions (questions like these will appear on the exam):

1. The roots of many plant species grow in association with mycorrhizal fungi. The plants supply the fungi with carbohydrates and the fungi help the plant with nutrient and water uptake. A). What type of relationship (or interspecific interaction) is this? B). Humans have altered the global cycle of nitrogen, a nutrient required for plant growth. In light of these changes, predict what changes will occur in the relationship between plants and mycorrhizal fungi. Describe an experiment that would test your predictions?

2. Some species of squirrels live in colonies. When on watch for predators, the squirrel calling the alarm was sometimes killed, but this allowed other members of the colony to seek shelter. In these species, males leave the burrow in which they were born and reestablish at some distance, while females stay close to home. Based on this 1) which sex is more likely to be sounding the alarm, and 2) why

3. While walking in the woods one day, you notice a dead squirrel on the side of the trail. It has only recently died and has not yet begun the process of decomposition. What will become of the nitrogen in this animal? Trace its flow through the ecosystem, and explain what happens to it at each step. How and for what is nitrogen used in living organisms? Is nitrogen released back into the abiotic environment as N2? Explain your answer.

4. Although secondary production is always lower than primary production, it also varies based on the type of ecosystem involved. What types of ecosystems do you think would have the highest amounts of secondary production? Why? Is it possible to increase secondary production in an ecosystem? If so, how? If not, is it possible to decrease it? Why or why not?

Short answer type questions (some of these questions will appear on the exam)

1. Why is it that density-independent factors can cause greater mortality than density-dependent factors, but that density-independent factors cannot "regulate" a population?

2. How important is vegetation cover to natural nutrient cycles? What evidence supports your estimate of importance?

3. How is it that predators act as evolutionary agents?

4. What defines a keystone predator? How does a keystone predator control the structure of a community?

5. How do parasites differ from predators?

6. Name three greenhouse gases and describe their contributions to the warming of the atmosphere during the past forty years.

7. Provide one hypothesis to explain why the ""earth is green"", i.e., to explain the low level of herbivory in terrestrial plant communities.

8. Why is competition a ( - / - ) type of interaction?

9. What is the difference between a realized and a fundamental niche?

10. What is a biogeochemical cycle?

11. The phosphorus (P) cycle differs from those of carbon and nitrogen in what ways?

12. Acid precipitation results from human alterations of which 2 biogeochemical cycles.

13. Why are zones of upwelling in oceans so productive?

14. The amount of energy moving through a food chain declines rapidly as trophic levels increase. Explain why this is so.

15. Each individual is faced with a trade-off in allocation of time and resources. Explain what this means in the ecological context of life histories by using an example of a specific organism.

16. What are gross primary production and net primary production and how do they differ? Why is this an important measure?

17. Most ecologists take 10% as an average ecological efficiency. What does this 10% represent? What happens to the other 90%?

18. How are nutrient cycles in terrestrial and aquatic ecosystems facilitated by microorganisms?

19. What is the difference between a proximate explanation for a particular behavior and an ultimate explanation for that behavior? Give
an example of each.

20. Optimality theory attempts to explain behavior using and cost/benefit approach. What are the costs and benefits of:

A. Territorial behavior
B. Living in Groups