Bio25_Sp'10_Ecol_Study_Qs_1

# Bio25_Sp'10_Ecol_Study_Qs_1 - Spring 2010 Sample Population...

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1 Clutch size (number of eggs) Nestling size Spring 2010 Sample Population & Community Ecology Study Review Questions (from past Bio 25 exams; see list of text questions on p.5) 1. Examine the graph (on the right); it shows a tradeoff between nestling size and clutch size. If nestling size had no effect at all on nestling survival or on the fertility of nestlings after they grew up, would you expect clutch size in a population to fall more on the left or more on the right side of the x-axis? Why? 2. Two closely related species of lizard, Anolis bigii and A. smalli, differ in how they invest resources into reproduction. Both species breed once a year, but individual A. bigii females annually produce 8-10 eggs weighing 10 grams each, while individual Anolis smallii females annually produce 40-50 eggs weighing 2 grams each. How do you predict the survivorship curves of these two species will differ, and why do you think so? 3. Imagine that you are tracking the reintroduction of Arabian oryx into the deserts of Saudi Arabia and Oman in 1982. At first, the population shows exponential growth. a) Draw a graph demonstrating what exponential growth looks like. Label both axes. You don't need to provide specific time units or specific numbers of oryx, just show what the shape of the growth curve looks like. Then, explain in one or two sentences what long-term outcome of continuous, unchecked exponential growth would be like. b) Later the population shows logistic growth. Draw a graph demonstrating what logistic growth looks like. Label both axes and show the expected shape of the growth curve. Then, explain in one or two sentences why the curve takes this shape. c) The logistic equation is given by the following relationship: dN dT = rN K N N where N is the population size and K is the carrying capacity. Describe in one or two sentences what the carrying capacity means . Then name one way you might manipulate the environment to change the carrying capacity. 4. In the Red grouse (a chicken-like game bird), populations typically show regular fluctuations in size (as in pop- ulation 1), but in a population treated with anti-roundworm drugs, population size does not fluctuate (population 2). A) Researchers working on this system concluded that roundworm infection was a density-dependent factor that caused the cyclical changes in population growht. Why might a disease act in this way? B) Are density dependent factors still acting on population 2? Explain your answer. Population 1 Population 2

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2 5. Beavers have been successfully re-introduced into much of their former range after being eliminated by fur trapping. In some locations, the populations have rebounded so well that the beavers have become a nuisance, and trapping has again been permitted. The life table below describes a cohort of beavers in Canada from a recovered population in which wildlife
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## Bio25_Sp'10_Ecol_Study_Qs_1 - Spring 2010 Sample Population...

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