1. Schmitz (1998) studied indirect interactions in a 3-level system: predator (Spider), herbivore (Grasshopper), and resources (Grass and Herbs). This plot shows Herb abundance with resources alone (1-level), resources and herbivores (2- level), and all three levels (Risk = spiders can’t eat, Predation =spiders eat). Based on these data, what how would you describe the impact of Spiders on Herbs here?
2. TMII and DMII
3. TMII but almost no DMII
4. DMII but almost no TMII
5. Neither TMII nor DMII

2. Sale (1979) did a removal experiment with territorial damselfish on coral reefs. They removed individuals of three species and asked whether the individual taking over that spot would be the same species. The circular arrows represent the same species returning, while the others represent a different species colonizing a spot. What result would be most consistent with the predictions from niche theory?
3. P. wardi replaces itself and takes over others’ sites.
4. Each species replaces itself the great majority of the time.
5. Each species takes over for others often, colonists are a more-or-less random “lottery”.

3. MacNeil et al. (2005) sampled stable isotopes in sharks to ask whether they preyed on bluefish (a large-bodied, high-trophic level species) that migrate through the area in spring. Liver tissue “turns over” quickly, so its isotopic signature reflects the animal’s recent diet more strongly than other tissues like cartilage. Which interpretation of these data is most consistent with your understanding of stable isotopes?

A..Makos feed on higher trophic level food all year long.

1. Makos prey on the spring bluefish much more than blue sharks and threshers do.
2. All three species eat lots of bluefish in the spring.

4. Which of the following would be an example of a trophic cascade?
5. Praying mantises consume ladybugs, thereby increasing the population density of aphids.
6. Mantises consume invasive Japanese ladybugs, thereby increasing the diversity of native ladybugs.
7. Beetles drill into trees, creating habitat under the bark for leafhoppers, aphids, and other invertebrates.

5. You collect two samples of invertebrates from two pots. Which diversity measure would indicate that Pot A had greater diversity than Pot B? Note that both A and B have the same proportions of the same taxa.

1. Shannon Index (H’) B. Probability of an Interspecific Encounter (PIE) C. Chao’s Estimator

6. Based on this plot from Chase (2003), what would be the β richness for a really isolated pond (neighbor distance = 1000m)? Remember that β richness = γ/α.

2. β = 1 B. β = 2.5                    C. β = 12                     D. β = 27

7. Which of these ponds would Chase (2003) say you’d be most likely to find a

1. Separation distance <100m
2. Separation distance 300- 600m
3. Separation distance >800m

8. The Theory of Island Biogeography holds that large islands should have more species. Which of these plausible explanations is the one MacArthur and Wilson proposed?
9. Large islands can host larger populations, which reduces extinction rates.
10. Large islands are big targets, so they have greater immigration rates.
11. Large islands have greater species turnover, so more species are there.

9. Based on the IUCN Red List, the primary force that has caused animals to become threatened or endangered is

1. Habitat loss
2. Invasive species
3. Climate change

10. Most of the time, a non-native species introduced to a new place never becomes common in the new place. How would Elton explain that failure?
11. Native species lack predators to limit their populations.
12. Native species have better adaptations for that local environment.
13. Native species represent more of the species pool, so they’ll “get lucky” in establishing themselves.

11. Atlantic cod were top predators in North Atlantic Ocean food webs. Their populations crashed in the 1990’s, and the abundance of phytoplankton (their food’s food’s food) has increased dramatically. This is an example of
12. Keystone predation
13. Ecosystem engineering
14. Trophic cascade

12. Herring worms are long-lived parasites of orcas. Based on what you know about trophic relations and stable isotopes, what would you expect to be true of herring worm tissue?
13. Ratio of δ¹⁵N to be about equal to that of orcas.
14. Higher ratio of δ¹⁵N than orcas.
15. Higher ratio of δ¹⁵N than free-living worms, but lower than orcas.

13. The simple web below goes from a top predator (A) to intermediate consumers (B, C, D) to phytoplankton (E and F). Suppose a disease wiped out species B. Which result would support top-down control of populations in this food web?
14. Populations of Species A decrease.
15. Populations of Species C increase.
16. Populations of Species D increase.

14. Suppose you had data for 20 open and 50 covered samples of soil invertebrates. Based on the richness observed in the samples collected, which type of habitat do you think has greater diversity?
15. open samples
16. covered samples
17. they have equal diversity
18. One important difference between the conservation of terrestrial and marine animals is that
19. Marine animals tend to disperse over far greater distances.
20. Marine animals have less complex life cycles.
21. Marine animals experience greater temperature stress due to climate change.

Short answers (6 pts unless noted otherwise)

1. The Oostvaardersplassen is a natural park in the Netherlands that aims to “re-wild” the wetland and grassland ecosystem near Amsterdam. What is the biggest difference between the current ecosystem and the one the planners were trying to re-create (eg, the area about 5,000 years ago)? What would you recommend they do to make the current system more closely match the “natural” state?

2. A new species of crayfish, which has European origin, appears in a pond in a nature preserve in VA. The plot shows the rank-abundance for taxa before the crayfish colonized the pond (open red) and after (filled blue).

(a) How has the crayfish altered the richness and evenness of the pond community?

3. Rangers in the Everglades cruise roads at night to survey mammal abundance. Their observations found that most mammals were far more common before pythons were present (green filled) than after they had established (red open).

Give two effects pythons could have on mammals to account for the decline in observations. Note that direct predation by pythons will not fit for either effect.

4. Potluck. Write a good question from this part of the course that could be worth six points. Note that good questions involve some analysis, not just ask respondents to report facts. “What is β diversity?” wouldn’t qualify, but “How would Chase (2003) expect β diversity to change in a network of ponds if you started fertilizing them regularly?” would.

(b) Write a full-credit answer to your question.

5. How to manage wild horses in western North America is a controversial topic. Given what we’ve read about them, make an argument for why we should or shouldn’t consider them to be a harmful invasive species here.

6. (3 pts) What advice would you give to students who were about to take this course? What should they do to be successful in this class? With your permission, I’ll attach some of your advice to next fall’s syllabus.

Equations galore!

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 Good luck!

Is this and multiple stable equilibria the same thing?