Classifying Community Interactions: Help, Harm, or No Effect

Chapter 54: Community Ecology
Concept 54.1 Community interactions are classified by whether they help, harm, or have no effect on the species involved.
1.What is a community? List six organisms that would be found in your schoolyard community.

2.This section will look at interspecific interactions. Be clear on the meaning of the prefix! To begin, distinguish between intraspecific competition and interspecific competition. Give an example of each.

Type of
Competition

Explanation

Example

Intraspecific
competition
Interspecific
competition

3.What is G. F. Gause’s competitive exclusion principle? Give one example.

4.Define ecological niche.

5.Several species of Anolis lizards live in the same types of trees and have a similar diet. Discuss
resource partitioning to explain how interspecific competition is reduced. (Study Figure 54.2.)

6.What is the difference between the fundamental niche and the realized niche?

7.

Study Figure 54.5, and then explain what is meant by character displacement. (To do this, you will have to learn or review the difference between sympatric populations and allopatric populations. You will find this information in Chapter 24.

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8.Predation is a term that you probably already know. Can you give examples of some predator-prey combinations as listed below?

Predator

Prey

Animal

Animal

Animal

Plant

Fungus

Animal

Bacteria

Animal

Fungus

Example

Plant

9.List three special adaptations that predator species possess for obtaining food.

10.List three ways prey species elude predators.

11.Compare the two types of mimicry.

Type of Mimicry
Batesian
Müllerian

Description

Example

12.What is herbivory?

13.Did you list any special herbivore adaptations for predation in your response to question 9? Or plant adaptations to avoid herbivory? List two adaptations for each category here.

14.Describe and give an example of each of the following interactions:

Type of
Interaction

Description

Example

symbiosis
parasitism
commensalism
mutualism

15.Which category above includes the other three? Note that other texts may define this term more narrowly.

16.Your text uses +/– symbols to indicate how interspecific interactions affect survival and reproduction of the two species. Use this notation for each of these interactions.

Type of Interaction
predation
commensalism
mutualism
parasitism
interspecific competition
herbivory

+/+, +/–, –/–, +/0

17.What is species diversity? What are its two components? Why is it important?

18.What does an ecologist summarize in a food web?

19.Know the levels of trophic structure in food chains. Give a food chain here, including four links that might be found in a prairie community, and tell the level for each organism.

20.Name every organism in the pictured food chain, and give the trophic level in the box.

21.According to the energetic hypothesis, why are food chains limited in length? How much energy is typically transferred to each higher level?

22.What is a dominant species? For the area where you live, what would be considered a dominant tree species?

24.Name one keystone species, and explain the effect its removal has on the ecosystem.

25.Explain facilitator or foundation species and give an example.

You may omit bottom-up and top-down controls.
Concept 54.3- Disturbance influences species diversity and composition 26.

What is the intermediate disturbance hypothesis? Give an example of a disturbance event, and explain the effect it has on the community.

27.Ecological succession is the changes in species that occupy an area after a disturbance. What is the difference between primary succession and secondary succession?

Concept 54.4 Biogeographic factors affect community biodiversity 28.

Explain latitudinal gradients in terms of species richness. Where is species richness greatest?

29.There are probably two key factors in latitudinal gradients. List and explain both here, and put a star next to the one that is probably the primary cause of the latitudinal difference in biodiversity.

30.Explain what is demonstrated by a species-area curve.

31.Renowned American ecologists Robert MacArthur and E. O. Wilson developed a model of island biogeography. While the model can be demonstrated with islands, any isolated habitat represents an island. What are the two factors that determine the number of species on the island?

32.What two physical features of the island affect immigration and extinction rates?

33.Why do small islands have lower immigration rates? Higher extinction rates?

34.Closer islands have

35.What is the island equilibrium model?

36.Use this model to describe how an island’s size and distance from the mainland affect the island’s species richness.

extinction rates and

immigration rates.

Concept 54.4 Community ecology is useful for understanding pathogen life cycles and controlling human disease
37.Let’s pull a couple of ideas from this section: What is a pathogen?

38.What is a zoonotic pathogen? List three examples.

39.What is a vector? List three examples.