Biology 463 Exam 3 sample questions
1. Contrast the community concepts of Clements and Gleason.
2. Clements’ and Gleason’s community concepts make different predictions
about the composition of communities as you move along an environmental
gradient. What is different about these predictions?
3. Describe how the Simpsons Diversity Index changes as a) species richness
increases, and b) as species evenness increases.
4. Draw rank abundance curves for 1) a population with low species richness
and low species evenness, and 2) a population with high species richness and
high species evenness.
5. Contrast the expected species richness through time in dominance and
founder controlled communities.
6. What is the difference between allogenic and autogenic environmental
change?
7. Under the Inhibition model of succession, what trend would you expect to
see in the characteristics of species in the community through time?
8. Under the Tolerance model of succession, what trend would you expect to
see in the characteristics of species in the community through time?
9. The replacement of legumes by non-nitrogen fixing plants through time
during succession is consistent with which of the three models (Inhibition,
Facilitation, Tolerance) of succession?
10. What observation (i.e. an empirical pattern based on the abundance of two
species) would be suggestive of a trophic cascade?
11. Give an example, with real species, of a trophic cascade that we’ve discussed
in class.
12. Describe the expected pattern of species richness as a function of:
a. The frequency of disturbance
b. Successional age (e.g. time since clearance of a field)
13. There are many examples of a positive correlation between species richness
and net primary productivity. Give two explanations for why one may
observe lower species richness at high levels of productivity.
14. MacArthur and Wilson’s theory of Island Biogeography suggests that the
equilibrium species richness on islands should depend on their distance from
a species pool (the mainland) and their size.
a. For a given island size, what effect do they predict that distance from
the mainland will have on species richness? And why?
b. For a given distance from the mainland, what effect do they predict
that island size will have on species richness? And why?
15. MacArthur and Wilson’s theory suggests that the equilibrium number of
species should be constant, but the actual species composition should vary
over time. Explain why this is so?
16. Dan Simberloff tested MacArthur and Wilson’s theory on mangrove islands in
Florida by altering island size. What observation did he make that confirmed
the theory of MacArthur and Wilson?
17. Many plants form mutualisms with ants. Describe one benefit that plants
provide for ants and one benefit that ants provide for plants in these
mutualisms.
18. Describe the benefits to the plant and the fungus in a tree/mycorrhiza
mutualism.
19. Describe why nitrogen fixing legumes are commonly successful as early
colonizers of patches, but are subsequently outcompeted by other plants.
20. What is the difference between Gross Primary Productivity and Net Primary
Productivity.
21. Give 4 limits to terrestrial primary productivity
22. What are the 2 major limits to aquatic primary productivity?
23. Describe why aquatic communities that are not limited by nutrients, may as a
consequence, be more limited by light.
24. Define Consumption efficiency.
25. Define Assimilation efficiency.
26. Define Production efficiency.
27. Rank forests, grasslands, and aquatic ecosystems in terms of the
consumption efficiency from primary producers to primary consumers –
explain why they go in this order.
28. Which tends to have higher assimilation efficiency, carnivores or herbivores?
29. Which has higher production efficiency, endotherms or ectotherms?
30. Only about 10% of NPP is transferred into the primary consumer trophic
level. What are 3 pathways that account for the other 90%
31. What is the difference between decomposers and detritivores?
32. For a population with logistic-like growth, draw the relationship between net
recruitment and population size.
33. On the figure you drew in 32, draw a horizontal line at the maximum
sustainable harvest level (the MSY).
34. What would happen to the population size and the harvest level if you
harvested less than the MSY?
35. For the figure you drew in 32, draw a line with the maximum level of fixed
harvest effort that achieves the MSY.
36. Describe why regulating harvest with fixed effort is more robust than
regulating effort with fixed quotas.
37. Describe why Montoya et al. suggested that the “rich-get-richer” model for
network assembly is unlikely to apply in ecological food webs.
38. Explain why Lyme disease incidence is positively correlated with coyote
abundance.
39. What is the dilution effect as defined for the Lyme disease example?
40. Give two explanations why Lyme disease risk may be higher in small forest
fragments.
41. What evidence from the Lyme disease example suggests that mouse
populations are limited from the bottom up?
42. Give two explanations for why the displacement of foxes might lead to higher
rates of Lyme disease.
43. What are the 4 possible fates of a unit of carbon ingested by a primary
consumer?
44. Give three ways in which humans impact the global carbon cycle.
45. Give two responses of plant communities to increased atmospheric carbon.