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Midterm2Key - Your name: _ EEB 122b SECOND MIDTERM Page 1...

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Your name: _____________________ Page 1 EEB 122b SECOND MIDTERM
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Your name: _____________________ Page 2 Question 1. A scientist is interested in understanding the biodiversity of the California Channel islands located off the coast of Southern California. The focus is on two islands, San Nicolas and Santa Cruz islands, that differ in total area and distance from the mainland of California. a) Using the map and axes provided, draw and label the curves that define the equilibrium conditions of San Nicolas and Santa Cruz islands (two curves for each island). Be sure to label each curve. (6 pts) b) Assuming each island is at equilibrium, which should we expect to have fewer species present? Briefly explain your answer. (3 pts) San Nicolas. It is smaller (higher extinction rate) and farther from the continent (lower immigration rate). d) The scientist spends an entire summer counting the number of species on each island and finds that the island predicted to have fewer species actually has more. Give one reason why this might be. (3 pts) Speciation could be occurring on the smaller, more distant island, where the local adaptive radiations could be overwhelming the effects of size and isolation on species number. Habitat heterogeneity on the larger island could actually be less than on the smaller island. Many other correct answers possible – Williamson’s critique lists several.
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Your name: _____________________ Page 3 Question 2. On an isolated oceanic island 3,000 miles from any continent, you find only 4 species: a flowering shrub, a rabbit, a large deer, and a small fox. a. Draw a food web for this island ecosystem (3 pts) b. Which species are in competition? (2 pts) The deer and the rabbit c. If predation is NOT the reason they can coexist, and the deer and the rabbit eat PRECISELY the same parts of the flowing shrub, at PRECISELY the same rates, then what explains how they manage to coexist? (2 pts) Intraspecific competition is stronger than interspecific competition d. Identify an empty niche. (2 pts) A predator that consumes deer e. An extreme weather event results in the extinction of the fox population. What change do you expect in the flowering shrub population? (3 pts) The shrub population would decrease Fox Rabbit Deer Shrub
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Your name: _____________________ Page 4 Question 3. You are studying a population of endangered Devil’s Hole pupfish ( Cyprinodon diabolis ). So far your research has produced this life table for a population from one pond: Age in years Survival, or the probability of an individual of age x surviving to age x + 1. (s x ) Fecundity, or the birth rate for individual of age x. (b x ) 0 to 1 0.1 0.0 1 to 2 0.2 0.0 2 to 3 0.0 50.0 a. Given this information calculate the number of individuals for the next two years. (6 pts) Age in years (X) # of age X (n x ) Year 1 # of age X (n x ) Year 2 # of age X (n x ) Year 3 0 250 250 250 1 25 25 25 2 5 5 5 b. What is the per generation rate of increase of (R o ) when the population is at stable age distribution? (1 pt).
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This note was uploaded on 02/07/2012 for the course EEB 122 taught by Professor Stephenstearns during the Spring '09 term at Yale.

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Midterm2Key - Your name: _ EEB 122b SECOND MIDTERM Page 1...

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