Chapter 6 Objective Questions
Population and Community Ecology
New England Forests Come Full Circle
1. When did deforestation peak after the colonization of the Pilgrims in the New England area?
2. What happened when people stopped farming the land?
3. How did predator/prey populations change over time?
4. What is the moral of this story?
Nature exists at several levels of complexity.
1. Differentiate between an individual, a population, a community, an ecosystem and the biosphere.
Population ecologists study the factors that regulate population abundance and distribution.
1. What does it mean to say a population is dynamic?
2. What is population ecology?
3. What is the basis of how populations change? See Figure 6.2
Population Characteristics
Population Size
1. What is N? If a population currently has 5,000 individuals and is growing at a rate of 10%, how
many individuals will be present after 20 years?
Population Density
1. What is population density?
2. What can scientists determine based on density and size?
3. How do wildlife managers use this in their management zones?
Population Distribution
1. What are the 3 types of distribution?
2. What types of organisms are found in these patterns?
3. How does each type of distribution benefit the population or the organism?
Population Sex Ratio
1. Most populations have what ratio of males to females?
2. What does this determine?
Population Age Structure
1. What do age structure diagrams tell us about a population?
2. What does age structure show if there is a larger population of older people than there are
younger people?
Factors That Influence Population Size
1. What are density-dependent factors? Examples?
2. What is a limiting resource? Examples?
3. What is the carrying capacity of a population (K)?
4. What does it tell us about an environment?
Density-Independent Factors
1. What are density-independent factors? Examples?
Growth models help ecologists understand population changes.
1. How do population growth models help scientists?
The Exponential Growth Model
2. What is growth rate?
3. What is the intrinsic growth rate (r)?
4. What can be predicted if you know the growth rate of a population (r) and the number of
reproducing individuals in the current population (N0)?
5. What is Nt?
6. What is the exponential growth model equation?
7. If a population currently has 5,000 individuals and is growing at a rate of 10%, how many
individuals will be present after 20 years?
8. When there are unlimited resources what would one expect to find happening to growth rate?
9. What will this type of growth show on a graph? Figure 6.5
10. What happens when a population reaches its carrying capacity?
You should learn about exponential growth, as it is what you want your future income savings to
do; that is if you are smart enough to start saving money, especially at an early age. First job …
monthly paycheck … put at least $100.00 into a Roth IRA account.
Do The Math Your Turn – Calculating Exponential Growth (p. 156)
The Logistic Growth Model
1. What is the logistic growth model?
2. What will this type of growth show on a graph? Figure 6.5
3. What types of constraints on populations will this model represent? Why not densityindependent factors?
Variations on the Logistic Growth Model
1. What is an overshoot?
2. What is a die-off?
3. What happened with the reindeer on St. Paul’s Island in Alaska? Figure 6.8
4. Explain the classis study of the lynx and hare predator/prey relationship. Why does the
population oscillate as it does in the graph in Figure 6.10?
5. Explain the wolves and moose changes in population numbers in Figure 6.11.
Reproductive Strategies and Survivorship Curves
K-Selected Species
1. What are characteristics of K-selected species? Examples?
r-Selected Species
1. What are characteristics of R-selected species? Examples?
2. Where do most species fall in the spectrum of reproductive strategies? Examples?
3. What are the three types of survivorship curves?
4. Examples of type I? Type II? Type III?
Make sure you know Table 6.1 and Figure 6.12
Metapopulations
1. What are corridors?
2. What is a metapopulation?
3. Why is the connectedness of importance to the existence of these populations? Examples?
Community ecologists study species interactions.
1. What three factors determine population distributions?
2. What four categories do the three factors fall into?
3. What are inter-specific interactions? What would intra-specific interactions be?
Competition
1. What is competition?
2. What is the competitive exclusion principle?
3. What is resource partitioning? Examples?
4. What are ways in which species in nature reduce resource overlap?
5. How do temporal resource partitioning and spatial resource partitioning differ? Examples?
6. What is morphological resource partitioning? Example?
7. What species does selection favor when two species compete for the same resources? Figure 6.15.
Predation
1. What is predation?
2. What are the four groups and examples of each?
3. What are examples of defenses organisms have evolved over time to defend themselves from
predators? Figure 6.17
Mutualism
1. What is mutualism?
2. What are two examples of this?
Commensalism
1. What is commensalism?
2. What are symbiotic relationships?
3. How do these different interactions affect the organisms? Table 6.2
Keystone Species
1. What is a keystone species?
2. How does the removal of a keystone species impact an ecosystem?
3. Explain the study between sea stars and mussels on the Washington State coast.
4. What is predator-mediated competition? Examples?
5. What does it mean to say that keystone species are ecosystem engineers? Example?
The composition of a community changes over time.
1. What is ecological succession?
Primary Succession
1. Under what conditions would one see primary succession? Examples.
2. What would be the sequence of colonization? Figure 6.23
Secondary Succession
1. Under what conditions would one see secondary succession? Examples.
2. What would be the sequence of colonization? Figure 6.24
3. What is a pioneer species?
4. What happens as this primary species progresses in its colonization?
5. What is the climax stage? A climax forest?
Aquatic Succession
1. Describe the process of aquatic succession.
The species richness of a community is influenced by many factors.
1. What determines the number and type of species found within a biome?
2. What four factors influence the above processes?
Latitude
1. What happens to species diversity as one moves from the equator to the poles?
Time
1. How does time play a role in species richness?
Habitat Size and Distance: The Theory of Island Biogeography
1. How does habitat size influence species richness?
2. How does distance between a habitat and a source of colonizing species determine species
richness? Figure 6.26
Conservation and Island Biogeography
1. The theory of island biogeography is not just about ocean islands but inland ones as well. How do
we create habitat islands?
Working Toward Sustainability – Bringing Back the Black-Footed Ferret
1. What happened to these two populations?
Work the 2 FRQ’s and the Measuring Your Impact to practice your math essay writing skills. The
multiple-choice questions are great examples of what you will see on the exam.