1. Begin discussion of communities by emphasizing that they are composed of various species.

2. Figure 27.1 shows that species are distributed independently of each other but in association with environmental changes.

1. Figure 27.2 illustrates how rare and common species are distributed and Figure 27.3 shows species richness across North America.

2. To illustrate species richness, go to two locations (e.g. a field and a park), sample a small quadrate in each, identify all species represented, and present the data, with slides showing the areas, to the class.

1. Show Table 27.1 and discuss how relationships involve species interactions, again emphasizing the fact that communities are made of various species.

2. Emphasizing Table 27.1 and positive, negative, and neutral interactions, give examples of each.

1. Make very clear the definition of ecological niche (See Concepts 27.1), and also how you will define niche and use the term.

2. Again, emphasize species interactions in discussing competition and the methods by which each species' niche is realized.

1. Present the competitive exclusion principle, discuss niche differentiation, and show Figures 27.6, 27.7, and 27.8, illustrating these ideas.

2. Also, mention that common space can be divided temporally, as with swifts and nighthawks, two species that should be familiar to students.

3. Types of competition should be distinguished, and examples of each presented (e.g. interference competition and resource competition).

1. Here again, emphasize species interactions and the fact that individuals don't evolve, populations do.

2. Give examples of allelopathy, ranging from common gardening techniques (e.g. planting marigolds as a border to deter pests) to specific coevolution situations (e.g. milkweed latex deters predation until a species evolves the ability to circumvent the poison), using Text Section 27.9 as a guide.

3. With the examples discussed in the area of "chemical warfare," show slides of these species (e.g. the milkweed bug and its host plant).

1. Show slides of plant species that create hostile environments for other competitive plants (e.g. the black walnut, Pinus species, the sunflower.)

1. Show Figure 27.10 and discuss this specific example of kairomones.

1. Emphasizing the species interaction theme, discuss predatory relationships as examples thereof.

2. Figure 27.11 shows that a prey's use of refuge depends on the density of its population.

3. Graph the three ways in which predators respond to prey population changes: numerical response, functional response, and aggregative response.

4. Show Figure 27.12 in discussing recruitment.

5. Obtain barn owl pellets from two or more different locations (British Columbia, Washington State, California) and dissect them to identify the prey species. Show slides of the pellet source locations, then bring the dissected pellets and data showing that prey selection varies based on location, weather, and prey availability.

1. Figure 27.15 is a nice illustration of correlated fluctuations in a host-parasite system.

1. To illustrate symbiosis, include slides of the animals and plants being discussed.

2. In discussing commensalism, show a slide of a sea anemone and clownfish, and also include Figure 27.17.

3. For parasitism, pictures of tapeworms are very effective, along with ectoparasites like ticks and fleas, and also brood parasites like the cuckoo (Figure 27.20).

4. For mutualism, again show slides of example species (Figures 27.21, 27.22).

1. Show Figure 2.20, the peppered moth, along with other camouflage examples (e.g. Figure 27.26).

2. Figure 27.25 is a nice illustration of not only camouflage but also of coevolution; use this to again stress the species interaction theme of this chapter.

3. Disruptive coloration can be illustrated by Figure 27.27 and to this add a nice film clip of a leopard walking through tall grass.

4. Figures 27.28 and 27.29 illustrate the search image concept.

1. Show slides of the monarch butterfly and its mimic, the viceroy (Figure 27.31), along with other examples of mimicry, such as the yellow-jacket wasp and various flies that have evolved similar coloration patterns.