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Exam 2 - 2010-Spring.pdf

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Department
Agronomy
Course
PCB 4043C
Professor
Christou
Semester
Spring

Description
code: Your Page 1 of 12 GENERAL ECOLOGY (PCB 4043) Spring 2010 EXAM 2 • Write your code on all the pages • Make sure that all pages are attached. • You may not use calculators, cell phones, brain chips, or other electronic aids. The math needed to solve a problem should be relatively simple. If you can't do the math, just show what needs to be calculated (e.g., "answer = .5 x .3") • If you get hung up on a problem, skip it; return to it after you’ve answered the “easy” problems. PAGE POOSNIBLE SCORE 1 2 _____ 2 6 _____ 3 8 _____ 4 8 _____ 5 10 _____ 6 10 _____ 7 6 _____ 8 11 _____ 9 10 _____ 10 11 _____ 11 8 _____ 12 10 _____ _____ _________ TOTAL 100 _____ 1-1. ( 2 points for either answer) Are you interested in being an undergraduate TA for this course next year?( YES, NO ) code: Your Page 2 of 12 2-1. A student doing an independent project (Zoo 4905) monitored Daphnia growth in a lake, and based on their performance was able to describe how the per capita growth rate varied as a function of density. Her data are shown below. 0.4 0.2 0 0 2 4 6 8 10 12 14 dN(per week) -0.4 Per Capita GrowDaphnia Density (no. / 10 ml) a) (4 points) Given enough time, to what density will the population converge if initiated at the following densities: Final Density N 0 = 1 N 0 = 3 N 0 = 7 N 0 = 14 b) (2 points) Give a biologically plausible explanation for this hump-shaped function (your answer must be sufficiently complete to explain both the rise and fall of the curve). code: Your Page 3 of 12 3-1. (2 points) Dr. I.M. Green monitored a plant population’s density through time (note the logarithmic scale): 1000 100 Den10ty 1 01 234567 89 01 time (years) Over which time period does the plant population exhibit the greatest per capita growth rate (circle the correct option)? i. 0-3 yrs ii. 3-6 yrs iii. 7-10 yrs iv. The answer can’t be obtained from the data available 3-2. The dynamics of three species can be described using the following equations (where N is density, in no./m ): dN /1 d1 = +1.0 – 0.1N – 011N 2 dN 2N 2t = +0.6 – 0.2N – 1.2N – 021N 3 dN /3 d3 = –0.1 + 0.1N 2 For each of the following, choose (i.e., circle) the best option from the those available within parentheses: a) (1 point) Species 1 and 2 are: ( competitors; predator and prey; mutualists, do not interact directly ) b) (1 point) Species 1 and 3: ( competitors; predator and prey; mutualists, do not interact directly ) c) (4 points) In the absence of Species 3, Species 1 and 2 will: ( both persist; only species 1 will persist; only species 2 will persist; neither will persist; there is not enough information provided ) hint: for c) apply the concept of invisibility. code: Your Page 4 of 12 4-1. The following life cycle diagram is based upon a time interval of one year. 0.3 0.1 0.5 Eggs 0.6 Small 0.5 Medium 0.3 Large 0.1 Adults Juveniles Juveniles Juveniles 20 a. (3 points) What proportion of individuals in each life stage survive from one year to the next? Eggs Jmvaeliles Adults b. (2 points) If there were 100 individuals of each stage on April 1, 2010, how many large juveniles should there be one year later (on April 1, 2011)? Javreniles c. (1 point) Given enough time (and assuming the transition values remain constant), this population will grow… (pick the best option): ( tangentially; density-dependently; exponentially; logistically ) d. (2 points) In the real-world, provide two reasons why the transitions could change (i.e., not remain constant). code: Your Page 5 of 12 5-1. ( 3 points) You observe that a species of butterfly very common on the Florida peninsula is absent from islands in the Florida Keys. Provide three hypotheses that might explain the absence of the butterfly from the islands. 5-2. ( 3 points) Two species of lizards that live in oak hammocks around Gainesville. Provide at least three hypotheses that might explain how the lizards are able to coexist in hammock environments. 5-3. ( 2 points) In class we’ve seen that increasing species richness can increase primary production. We’ve also discussed coexistence of competitors. Combine these concepts to explain why increased species richness might increase primary production. 5-4. ( 2 points) You work for the USDA and you have been charged with finding a biocontrol agent that might stem the outbreak of pine beetles. Explain at least two key traits of a biocontrol agent that you’d look for: code: Your Page 6 of 12 6-1. Define: a) (1 point) Exploitative competition b) (1 point) Interference competition c) (1 point) Functional response d) (1 point) Indirect effect e) (1 point) Higher order interaction 6-2. (2 points). Provide one explanation for why decomposition of soil organic matter is slow in the arctic. 6-3. ( 3 points). List three reasons why the marsh cordgrass, Spartina alterniflora, is considered a pioneer species in the development of eastern U.S. salt marshes. code: Your Page 7 of 12 7-1. ( 6 points). You work for the National Marine Fisheries Service. A new species of sea life has been discovered and it makes awesome sushi. You have been charged with coming up with a manage
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