Exam 2. Principles of Ecology. March 10, Name

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1 Exam 2. Principles of Ecology. March 10, Name N t = N o λ t N t = N o e rt N t+1 = N t + r o N t (1-N t /K) N t = K/(1 + [(K N o )/N o ] * e rt ) dn/dt = rn(1-n/k) N captured and marked initially = N marked at recapture N total N total recaptured Multiple guess. Pick the best answer. [5 points each, 30 pts total] 1. Andrewartha and Birch (1954) argued which of the following factors was least important in determining the size of the summer population of Thrips? a. winter temperature. b. amount of spring rainfall. c. spring temperature. d. size of overwintering population. e. none of the above, they re all equally important. 2. What s the doubling time of a population growing geometrically and that changed from 250 to 300 individuals in one year? a. 3.8 years. b. 4.2 years. c. 5 years. d. 20 years. e. it will never double. 3. Assume that a species of tree has seeds that are light and wind-dispersed and that, in a given area, it is the only species of tree present. The expected dispersion pattern of seeds and trees, respectively, would be best described as a. clumped and random. b. random and random. c. random and uniform. d. random and clumped. e. uniform and random. 4. If a null hypothesis (H o ) is supported then which of the following must have had to be true? a. p b. p α. c. p > α. d. α p. e. none of the above. 5. The best measure of fitness is a. whether individuals are able to reproduce. b. the type of offspring produced by an individual relative to the types of offspring produced by all other individuals. c. the number of offspring produced by an individual. d. the number of offspring produced by a genotype relative to the number produced by other genotypes. e. how long an individual lives. 6. Imagine you are estimating a population of fleas on a dog and use the mark-recapture technique. On the first capture you catch and mark 120 fleas with little yellow dots. On the second capture you get 50 fleas and find 10 are marked. You then discover that the dog can better see the marked fleas and preferentially chew them up. What s your original estimate of the population and your interpretation of that estimate given your discovery? a. 240, but it s an overestimate of the population (there are really fewer fleas in the population). b. 240, but it s an underestimate of the population (there are really more fleas in the population). c. 300, but it s an overestimate of the population (there are really fewer fleas in the population). d. 300, but it s an underestimate of the population (there are really more fleas in the population). e. 600, but it s an overestimate of the population (there are really fewer fleas the population). f. 600, but it s an underestimate of the population (there are really more fleas in the population). Principles of Ecology, Exam 2 Page 1 of 6

2 Answer FIVE short answers questions (10 pts each, 50 pts total) 1. We spent some time talking about a very simple model of cooperation where each individual is represented simply as a probability of cooperating. You might be a 0.9, meaning that you ll cooperate, on average, 90% of the time. Briefly describe the three conditions that lead to global cooperation. a. b. c. 2. Identify three results from the graph of reaction norms for the growth rate of swallowtail butterfly caterpillars. 3. Define sexual dimorphism AND provide three plausible explanations for its evolution. [student submitted] 4. Provide a graph of growth rate versus density for density-dependent growth and a second graph for densityindependent growth. Show how these two models affect population density changes over time. 5. We hear about statistics a lot in the news and in biology. What do we mean by statistics and why do we use them in ecology? Principles of Ecology, Exam 2 Page 2 of 6

6. Produce a graph for a population growing according to the logistic growth equation with N o = 100, r = 0.1, K = 500. On the same graph do this with N o = 600, r = -0.1, K = 500. Identify everything and be sure to label your axes.

3 6. Produce a graph for a population growing according to the logistic growth equation with N o = 100, r = 0.1, K = 500. On the same graph do this with N o = 600, r = -0.1, K = 500. Identify everything and be sure to label your axes. 7. The Leslie matrix approach to modeling population utilizes a great deal of detailed data on population fecundity and probabilities of survival. If you predict the numbers of individuals in each age or size class over several time periods an even-age or size class develops over time. How can this useful to help conserve an endangered species? 8. Using a sentence or two describe Cole s Paradox. (3 pts) We saw this page on the Mysterious self-destructing palm tree. The piece says the tree has a bizarre, unusual reproductive cycle, whereby flowering actually kills the tree. Explain this bizarre behavior quantitatively. (7 pts) Principles of Ecology, Exam 2 Page 3 of 6

4 9. In the square to the right please draw a population that at the largest scale is randomly dispersed and uniformly dispersed at the smallest scale. Note that I am not asking for three different maps showing three different patterns. This is a single map. Also, what determines that scale is important to ecological systems? 10. Based on the work by Hartvigsen et al. explain how to achieve global cooperation where individuals are represented simply as probabilities of cooperating and reside on a chessboard-like universe. 11. In the Arboretum we discussed the evolution of grasses. Using a histogram discuss how natural selection (and specifically what type of selection) has likely operated on grass morphology to produce this interesting plant. Principles of Ecology, Exam 2 Page 4 of 6

5 Answer TWO of THREE questions. (10 pts each, 20 pts total). 1. What are the four easily observed characteristics of natural selection? (1 pt each but -2 for first missed) a. b. c. d. e.. Provide a graph of data that we have seen that is consistent with two of the above characteristics of natural selection. (5 pts) 2. If a population grows with the following Leslie matrix, what will the population be in each of the next three time steps (N 1, N 2, and N 3 )? The provided population is from time step zero. Show your work. Calculate λ for the following time steps a. 0-1 b. 1-2 c. 2-3 Principles of Ecology, Exam 2 Page 5 of 6

6 3. Analyze the graph on the left and complete the graph of N versus time on the right (5 pts each). Use each dot as a starting place for a population. Note that b o and d o represent birth and death rates, respectively. Extra Credit 1. What did you learn about placebos in PoE lecture? (2 pts) 2. Why is Hartvigsen s friend jealous of people who smoke? (2 pts) [Student submitted question] 3. a. What s the name of the organism in the photo below? (2 pts) b. Where s it found or from? (1 pt) 5. What opportunity at Geneseo offers students $500/wk for six weeks? (be specific - 2 pts) Principles of Ecology, Exam 2 Page 6 of 6

Exam 2. Principles of Ecology. March 25, Name

Exam 2. Principles of Ecology. March 25, 2009. Name N t = N o λ t N t = N o e rt N t+1 = N t + r o N t (1-N t /K) N t = K/(1 + [(K N o )/N o ] * e rt ) dn/dt = rn(1-n/k) N captured and marked initially