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Environmental Biology Exam II: Questions and Answers - Prof. Nicholas James Gotelli, Exams of Ecology and Environment

The questions and answers for exam ii in environmental biology 102, taught by professor gotelli during the fall 2002 semester. The exam covers topics such as statistical analysis, island biogeography, competition, and predator-prey dynamics.

Typology: Exams

2010/2011

Uploaded on 06/07/2011

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Biology 102 Gotelli
Environmental Biology Fall 2002
Page 1
Exam II
Name________________________________________
Total = 100 points
1 (12 points) _________
2 (12 points) __________
3 (25 points) __________
4 (10 points) __________
5 (15 points) __________
6 (6 points) __________
7 (5 points) __________
8 (15 points) __________
There are 4 pages and 8 questions.
To receive full credit for numerical problems, show your calculations and give
the correct units for your answer. Partial credit will be given, so try to provide an
answer for all questions.
1. You are carrying out an experiment to test the hypothesis that character
displacement is responsible for shifts in jaw length of two island lizard species
(Anolis grismani and Anolis grappelli). For each species, you measure the jaw
length of specimens collected from allopatric and sympatric populations. Here
are the mean values of jaw length in these four groups:
Species Allopatric Populations Sympatric Populations
Anolis grismani 7.5 mm 12.5 mm
Anolis grappelli 8.5 mm 13.5 mm
You use a statistical test to assess the differences in jaw length among these
four groups. Your statistical test produces a probability p = 0.006.
a) Carefully explain the meaning of “p = 0.006” in this test. Will you accept or
reject the null hypothesis? Explain your reasoning. (6 points)
b) Does your statistical analysis tend to confirm or refute the hypothesis that
character displacement has led to shifts in jaw size of these lizards? Briefly
explain your reasoning. (6 points)
pf3
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Environmental Biology Fall 2002

Exam II

Name________________________________________

Total = 100 points

1 (12 points) _________ 2 (12 points) __________ 3 (25 points) __________ 4 (10 points) __________ 5 (15 points) __________

6 (6 points) __________ 7 (5 points) __________ 8 (15 points) __________

There are 4 pages and 8 questions.

To receive full credit for numerical problems, show your calculations and give the correct units for your answer. Partial credit will be given, so try to provide an answer for all questions.

  1. You are carrying out an experiment to test the hypothesis that character displacement is responsible for shifts in jaw length of two island lizard species ( Anolis grismani and Anolis grappelli ). For each species, you measure the jaw length of specimens collected from allopatric and sympatric populations. Here are the mean values of jaw length in these four groups:

Species Allopatric Populations Sympatric Populations Anolis grismani 7.5 mm 12.5 mm Anolis grappelli 8.5 mm 13.5 mm

You use a statistical test to assess the differences in jaw length among these four groups. Your statistical test produces a probability p = 0.006.

a) Carefully explain the meaning of “p = 0.006” in this test. Will you accept or reject the null hypothesis? Explain your reasoning. (6 points)

b) Does your statistical analysis tend to confirm or refute the hypothesis that character displacement has led to shifts in jaw size of these lizards? Briefly explain your reasoning. (6 points)

Environmental Biology Fall 2002

  1. List the assumptions of the simple island-mainland metapopulation model. (12 points)
  2. You are studying competition between red and black desert scorpions. For the red scorpion, K 1 = 75 and α = 0.5. For the black scorpion, K 2 = 60 and β = 1.0.

Suppose the initial population sizes are 30 red scorpions and 30 black scorpions. Plot these initial population sizes. Graph the state space and isoclines for each species, and the trajectories of population change. Be sure you label both axes and indicate the values at which each isocline crosses the x or y axis. (15 points)

Predict the short-term dynamics of each population and predict the final outcome of interspecific competition. (10 points)

Environmental Biology Fall 2002

  1. What determines the period and the amplitude of the cycles in the predator- prey model? (6 points)
  2. What was the main thesis of Professor Bartlett, the speaker in last Wednesdays’ video? Were you persuaded by his arguments? Why or why not? (5 points)
  3. Define or explain the following terms (3 points each) :

rescue effect

competition coefficient (alpha (α))

escape in numbers

sink population

rescue effect