Ecology: Biomes, Foraging, and Population Dynamics - Prof. Bruce E. Lyon, Exams of Biology

Download Ecology: Biomes, Foraging, and Population Dynamics - Prof. Bruce E. Lyon and more Exams Biology in PDF only on Docsity! 1 Name___________________________ BIOLOGY 150 Midterm Exam Winter 2001 BEFORE YOU START: WRITE YOUR NAME ON EACH PAGE!!!! Read the questions carefully before answering to ensure that you fully understand what we are looking for. Answer the questions in sufficient detail to let us know that you fully understand the critical issues. Do not use the shotgun approach of throwing everything under the sun into your answer in the hope that something will hit the target because we may deduct points for statements that are counter to the correct answer. Good luck and wow us with your ecological knowledge! PART A. Shorter answers, graphs or calculations. Your answers can be in point form but must be complete. 1. Biomes provide a striking example of a match between organisms and their environment on a broad geographic level. (i) Name two biomes and identify a key feature of each (4 points): Biome Feature (ii) If we were to compare two plants that occur in the same biome, say desert, but each occurs on a different continent, would this comparison be more likely to provide an example of an adaptive radiation or an evolutionary convergence? Explain why. (2 points) 2. Outline the key features aspects that together produce the process of natural selection. Which part is ecological, and why is it ecological? (6 points). 2 Name___________________________ 3. The photo below shows a clear pattern: a bush surrounded by a bare area of soil with grass and other vegetation growing beyond the bare patch. Describe two different ecological mechanisms that could account for this pattern. Outline experiments you could conduct to test EACH of the two hypothesized mechanisms. For each hypothesis, discuss what result from your experiment would refute the hypothesis and what result would support the hypothesis (8 points). Paste Krebs photo here 4. The cost of inbreeding may favor the evolution of dispersal because individuals that fail to disperse may mate with relatives leading and produce less viable or inviable offspring. Outline an experiment you could do with plants to test for a cost of inbreeding. Be sure to identify any critical assumptions you make, and indicate what result from your experiment would indicate a cost to inbreeding (5 points). 5 Name___________________________ 8. The population growth rate per individual, r, is a very useful population parameter that is used in many population models. (i) If r = 2.4/year, what is r per month? (2 points) (ii) If r > 0, what would the pattern of population growth look like on the two graphs below? The dot indicates the starting population size (2 points). Time N Population size Natural log (ln) population size Ln N Time (iii) How could you estimate r from the right graph above? (1 point) 9. Match the graphs below to each of the following and write the graph letter in the space provided. There are more graphs than spaces to fill (Hint: pay attention to the axis labels). (4 points) (a) _____ Density-independence (b) _____ Exactly compensating density-dependence (c) _____ Allee effect (d) _____ Overcompensating density-dependence Density Number surviving A Density Number surviving Mortality rate Density Density Number surviving B C D Density Mating probabil i ty E 6 Name___________________________ 10. The graph below shows a population that fluctuates over time in a pattern known as chaos. Time N (i) What exactly is chaos? (2 points) (ii) Is chaos produced by random (stochastic) events and how do you know? (2 points). (iii) If the above population dynamics are chaotic, then we should see the signature of chaos when plotted on the graph below. Fill in the signature of chaos (2 points) Nt+1 Nt 11. The spatial distributions shown below represent: (3points) (a) ________random dispersion (b) ________uniform or spaced dispersion (c) ________clumped dispersion A B C Describe one ecological mechanism that could produce pattern B and one that could produce pattern C (2 points). 7 Name___________________________ 12. You are given the task of conserving a population of the Yellow-bellied Snorters. On your annual census, you notice that the population fluctuates in overall survival and production of young, and this is reflected in your estimates of λ across years. In good years you find that λ = 3.0, in bad years λ = 0.2. You also note that good and bad years occur with equal frequency. Your colleague insists that the snorter population is in fine shape because the arithmetic mean of λ is 1.6 and when they plugged this value into a deterministic population model, the population is predicted to grow quickly over the long-term. Being a well-trained ecologist, you correct them and insist that a stochastic population model is needed here. a) What is the fundamental difference between a stochastic population model and deterministic population model? (2 points). b). Even without running any model you can do a quick calculation with the above λ values to obtain the correct estimate of an ‘average’ λ value that accurately predicts long-term prospects for the bear population. Show this calculation. Is the population growing, stable or declining over the long-term? Why? (4 points). 13. Body size affects just about all aspects of an organism’s life. Due to allometric relationships between body size and many fundamental physiological and ecological variables, very small and very large animals live very different ecological lives (5 points) (i) Whole organism metabolic rates scale Mass 0.75 with body size in the standard log-log plot. Given this, do smaller animals have larger or smaller whole organism metabolic rates than bigger animals? (1 point) (ii) Mass specific metabolic rates scale Mass -0.25 with body size in the standard log-log plot. Given this, do smaller animals have larger or smaller mass specific metabolic rates than bigger animals? (1 point) (iii) Describe three important ecological consequences of these relationships to the challenges faced by tiny animals (shrews, hummingbirds) versus large animals (deer, whale). (3 points) 14. Density-dependence is of special interest to ecologists because it can potentially explain what limits population growth in some species. In addition, it also provides a possible