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UNIVERSITY OF MICHIGAN
Test 2 Comprehensive Review of
Competition and Fitness
Concepts
Course: BIOL 173 BIOLOGY LAB
, Quiz Questions:
One can measure biological competition and determine superior vs. inferior competitors.
Yet, competition is said to be detrimental to all species facing it. Explain this seeming
paradox.
• One organisms may do better than the other but neither does as well as it would by itself.
They both have to work hard to get those limiting resources.
• All organisms require resources to grow, reproduce, and survive. For example, animals
require food (such as other organisms) and water, whereas plants require soil nutrients (for
example, nitrogen), light, and water. Organisms, however, cannot acquire a resource when
other organisms consume or defend that resource. Therefore, competitors reduce each
other's growth, reproduction, or survival.
Define competition: An interaction between species that harms them both. (both species need/
share a limiting resource)
Comparing the height of tomato plants in a 50T pot with the height of tomato plants in a
25T/25A pot tells us about the relative strength of intra- vs. inter-specific competition.
Explain that.
• 50T tells you about intraspecific competition, how ―extra‖ T lowers growth of the T
• 25T/25A tells you about interspecific competition, how extra A lowers growth of T
• If height of T in 50T > Height of T in 25T/25A, then A is stronger competitor than T
How should we interpret the following hypothetical results? Assume all differences are
significant (three points) Height, 25T- 100 mm
Height, 50T- 50 mm
Height, T in 25T/25A- 150 mm
• 25T vs. 50T: tells you intraspecific competition is happening
• height of T in 25T/25A is higher than 50T, but it’s also higher than 25T.
• That means 25A are actually helping T (mutualism, cross-feeding?)
If the data say plant P grows taller in a pot with 50P than in a pot with 25P and 25Q,
which is more severe for plant P, intra- or inter-specific competition? Explain.
• Inter-specific is worse.
• P plants do better with 25 extra of their own kind (50P) than with an extra 25Q.
Using hypothetical plants P & Q again, what result(s) would tell you that P & Q were in a
mutualistic relationship?
• P plants in 25P/25Q > P plants in 25P and
Q plants in 25P/25Q > Q plants in 25Q
means closer means further apar
Circle the factors below that are associated with a MORE smaller variance larger variance
significant result smaller sample larger sample
• T-score: HIGHER values of the t-score, indicate that a large lower T-score higher T-score
difference exists between the two sample sets. lower p value higher p value
• Means: FARTHER apart, large difference exists between the
two sample sets
• Sample size: LARGER, Larger sample sizes provide more accurate mean values, identify
outliers that could skew the data in a smaller sample and provide a smaller margin of error.
UNIVERSITY OF MICHIGAN
Test 2 Comprehensive Review of
Competition and Fitness
Concepts
Course: BIOL 173 BIOLOGY LAB
, Quiz Questions:
One can measure biological competition and determine superior vs. inferior competitors.
Yet, competition is said to be detrimental to all species facing it. Explain this seeming
paradox.
• One organisms may do better than the other but neither does as well as it would by itself.
They both have to work hard to get those limiting resources.
• All organisms require resources to grow, reproduce, and survive. For example, animals
require food (such as other organisms) and water, whereas plants require soil nutrients (for
example, nitrogen), light, and water. Organisms, however, cannot acquire a resource when
other organisms consume or defend that resource. Therefore, competitors reduce each
other's growth, reproduction, or survival.
Define competition: An interaction between species that harms them both. (both species need/
share a limiting resource)
Comparing the height of tomato plants in a 50T pot with the height of tomato plants in a
25T/25A pot tells us about the relative strength of intra- vs. inter-specific competition.
Explain that.
• 50T tells you about intraspecific competition, how ―extra‖ T lowers growth of the T
• 25T/25A tells you about interspecific competition, how extra A lowers growth of T
• If height of T in 50T > Height of T in 25T/25A, then A is stronger competitor than T
How should we interpret the following hypothetical results? Assume all differences are
significant (three points) Height, 25T- 100 mm
Height, 50T- 50 mm
Height, T in 25T/25A- 150 mm
• 25T vs. 50T: tells you intraspecific competition is happening
• height of T in 25T/25A is higher than 50T, but it’s also higher than 25T.
• That means 25A are actually helping T (mutualism, cross-feeding?)
If the data say plant P grows taller in a pot with 50P than in a pot with 25P and 25Q,
which is more severe for plant P, intra- or inter-specific competition? Explain.
• Inter-specific is worse.
• P plants do better with 25 extra of their own kind (50P) than with an extra 25Q.
Using hypothetical plants P & Q again, what result(s) would tell you that P & Q were in a
mutualistic relationship?
• P plants in 25P/25Q > P plants in 25P and
Q plants in 25P/25Q > Q plants in 25Q
means closer means further apar
Circle the factors below that are associated with a MORE smaller variance larger variance
significant result smaller sample larger sample
• T-score: HIGHER values of the t-score, indicate that a large lower T-score higher T-score
difference exists between the two sample sets. lower p value higher p value
• Means: FARTHER apart, large difference exists between the
two sample sets
• Sample size: LARGER, Larger sample sizes provide more accurate mean values, identify
outliers that could skew the data in a smaller sample and provide a smaller margin of error.
