collecting data, perhaps with no hypothesis in mind, followed by
testing for patterns, and, when confronted with patterns, trying to
explain them. In addition, students will get a glimpse into the complexity of symbiotic relationships. The exercise can be used for a
variety of levels of students; it is up to the instructor to decide
how far to take the presentation of data and the analyses.
I thank the Acadia student newspaper, the Athenaeum, for publishing an article about tar spot fungi many years ago that inspired me
to create this lab. I also thank the many students who have now
collected data in multiple years; the patterns that emerged encouraged me to publish this article. Finally, I thank a very insightful
reviewer for a wealth of valuable suggestions and guidance that
substantially improved the paper.
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DAVE SHUTLER is a Professor in the Department of Biology, Acadia
University, Wolfville, Nova Scotia B4P 2R6, Canada.
Table 4. Comparison of the number of tar spots on leaves with different attributes (ANOVA).
Category 1 Mean Spots Category 2 Mean Spots F1, 1548 P
On tree 4. 2 On ground 3. 2 25. 3 <0.001
Green 3. 7 Yellow 3. 8 0.4 0.54
Forest 5. 3 Residential 3. 2 100.6 <0.001
Table 3. Analysis of the association between leaf color and habitat (χ2 1 = 19. 8, P < 0.001), and between
leaf color and whether the leaf was on a tree or on the ground (χ2 1 = 601.9, P < 0.001).
Color Forest Residential
Green 247 815
Yellow 166 322
On the Tree On the Ground
Green 820 242
Yellow 52 436