Ecology 203, Exam III. November 16, Print name:

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1 Ecology 203, Exam III. November 16, Print name: Read carefully. Work accurately and efficiently. The exam is worth 100 points (plus 6 extra credit points). Choose four of ten concept-exploring questions (40%). There are three Principles of Ecology questions (30%). Some potentially useful equations: N t = N o λ t dr/dt = rr crp dn 1 /dt = r 1 N 1 (K 1 N 1 α 12 N 2 )/K 1 N t = N o e rt dp/dt = acrp dp dn 2 /dt = r 2 N 2 (K 2 N 2 α 21 N 1 )/K 2 H = - Σ [p i * ln(p i )] dn/dt = rn(1-n/k) drh/dt = L o V*E^s + e c *OλO*G y Multiple alternatives. Circle the best answer (3 pts each, 30 pts total) 1. Which of the following is not a mechanism governing plant community development? [TB: ] a. Facilitation (species "paving the way" for the next species) b. Inhibition (climax species inhibiting previous species within community development) c. Seasonal cycles (warming and cooling over the year, regardless of magnitude, which is necessary for community development) d. Tolerance (indifference of the establishment of one species based on the presence of others) e. None of the above (they re all well-established mechanisms of development) 2. In addition to having No life support tattooed on his chest, Frank Egler contributed which of the following hypotheses? (L, reading on the web) a. species-area relationship. b. initial floristics composition model. c. resource availability hypothesis. d. food web functional relationship hypothesis. e. resource apparency model. 3. Which of the following is not an adaptation of prey to avoid predation? [L, TB: 334] a. chemical offense b. chemical defense c. crypsis d. predator satiation e. reduced population growth rates 4. The graph on the right of the number of lynx as a function of the number of bunnies is consistent with which of the following models: [L, TB: 359] a. intraspecific competition b. host-pathogen. c mutualism. d. predator-prey. e. none of the above (it s like predator-prey but contradicts those predictions by cycling in a counter-clockwise direction). Page 1 of 8

2 5. The movie on the diversity of trees on Barro Colorado Island in Panama presented the Janzen-Connell hypothesis of tree species diversity. This hypothesis suggests that diversity of trees is [L, TB: 455-6] a. maintained by the increased death of seedlings around the mother trees. b. decreased due to insects and fungi. c. highest near the parent tree because that s where seeds fall. d. all of the above. e. none of the above. 6. We spent some time discussing why the world is green. The field guide discussed this, too, focusing on which of the following important aspects of this phenomenon? [FG: (maybe)] a. Low nitrogen concentration in plants. b. Mechanical and chemical defenses in plants. c. The difficulty herbivores have in finding edible plants (apparency theory). d. All of the above. e. None of the above. Trick question - the field guide didn t discuss this at all! 7. An important principle of ecology is the species-area relationship. This relationship suggests that (L, FG: 213, TB: 415) a. the number of species is positively related to the size of the area sampled. b. the number of species is positively related to the size of the area sampled. c. conservation is particularly important where there is an inverse relationship between the number of species and area. d. areas of highest diversity are areas with the highest species richness. e. All of the above are critical aspects of this principle. 8. Gause s landmark experiments on the coexistence of species in laboratory cultures led to (Ricklefs, page 369) which of the following principles of ecology? [L, TB: 369] a. competitive exclusion principle. b. competitive coexistence principle. c. the intermediate disturbance hypothesis. d. response to competition model. e. all of the above. 9. The beaks of the Galapagos finches were found to be similar on small islands but different when the birds of two species were found on the same, larger island. These data are probably best explained through which of the following principles of ecology? [L, TB: 390] a. competitive exclusion modified by Lotka-Volterra predator-prey effects. b. character displacement resulting from competition. c. intelligent design that yields well adapted beaks for feeding on available food sources. d. reciprocal coevolution. e. none of the above. 10. If individuals of two species, when grown together, both decrease in size while members of one species is reduced more than members of the other species, which of the following best describes this outcome? a. This is a response to competition with compensatory growth. b. One species is a mutualist of the other. c. This is both a response to competition and the emergence of competitive asymmetry. d. All of the above. e. We don t have enough information to make a conclusion. Page 2 of 8

3 Concept-exploring questions. Since you only have to answer 4 of 9 you should do a good job. Clearly circle the numbers of the question you want me to assess. Otherwise, I ll assess the first four questions that have some writing in them. (10 pts each, 40 pts total) 1. Based on our discussions of food webs, list the three types of webs (how species are connected ), briefly define each, and discuss which is most important to use to understand a food web and why. [TB: , L] 2. Define keystone species and discuss why there can be or can t be a keystone plant. [TB: 408, L] 3. Provide a graph of predator satiation and briefly describe why your graph represents this phenomenon. [L] 4. Community A has four species with 300, 350, 400, 2000 individuals and community B has three species with 10, 15, 20 individuals. Calculate the following: (L, TB: 417) Community A B Species Richness Shannon-Weiner (H ) Quantitatively, which community is more diverse? Explain. Page 3 of 8

4 5. Graph the herbivore optimization hypothesis. Explain whether this could or could not occur in a predator-prey relationship. Label your axes clearly. (L) 6. What do we mean when we ask why is the world green? Provide two well-defended reasons why the world is green. [L, TB: 340, FG: ] 7. Provide a graph the fundamental and realized niches of red and gray squirrels that coexist in the Research Reserve. Both squirrels eat seeds and sleep in nests of some sort. Make this graph so that the fundamental niches overlap along two resources and the realized niches overlap for just one of the resources. Label the axes carefully. Page 4 of 8

5 8. Is the viceroy butterfly a Mullerian or Batesian mimic of the monarch butterfly? Explain with a graph of the distribution of the trait for both species. [L, TB: ] 9. Draw a graph based on realistic data that is consistent with the intermediate disturbance hypothesis. Label axes clearly. In addition, provide a quantitative definition of your y-axis variable (what you measure). (L, TB: 417, 454) 10. What are the assumptions of Henry Horn s Markov-chain model? Describe what data you would collect and how you d set up this model for two species in the Research Reserve forest. Page 5 of 8

6 Principles of Ecology questions. Answer each of these. (10 pts each, 30 pts total) 1. Lotka-Volterra competition model. (10 points) Label axes and lines for the graph on the left below. Analyze the graph. Using arrows show where the two populations end up assuming they follow the standard Lotka-Volterra competition model. Begin at the dot in the left graph. On the right make a graph of N versus time for this system, assuming the two species begin at the dot on the left. Label the axes. Follow them until they reach an equilibrium. K 1 Page 6 of 8

7 2. Lotka-Volterra predator-prey model. (10 pts) Assume predator and prey populations grow according to the model described below on in the graph on the left. Identify the equilibria lines for the two species. With arrows pointing to parts of the left graph identify the principles of ecology that lead to the bending of the isoclines. Draw the trajectory of the two species in the left graph, starting at the dot. Analyze the graph. On the right provide a graph of N versus time and assume that the two species begin at the dot on the left graph. Label all axes. (10 pts) Page 7 of 8

8 3. Draw the graph for the equilibrium number of species predicted by the theory of island biogeography. Do this for four islands (two small islands that are near and far, and two large islands that are near and far). Analyze the graph. Provide a second graph of what the number of species would look like on an island before, during, and after a hurricane swept through. [L, TB ] (10 pts) Extra Credit 1. What are the four easily observed characteristics of natural selection (2 pts for completely correct answer). 2. In the 1960 paper, Hairston, Smith, and Slobodkin argued what? (2 pts). Provide a figure (2 pts). Identify two important outcomes from this work (2 pts). Page 8 of 8