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)
