1. Chapter 8 Community Ecology

2. Core Case Study: Why Should We Care about the American Alligator?  Hunters wiped out population to the point of near extinction.  Alligators have important ecological role. Figure 7-1

3. Core Case Study: Why Should We Care about the American Alligator?  Dig deep depressions (gator holes). Hold water during dry spells, serve as refuges for aquatic life. Hold water during dry spells, serve as refuges for aquatic life.  Build nesting mounds. provide nesting and feeding sites for birds. provide nesting and feeding sites for birds. Keeps areas of open water free of vegetation. Keeps areas of open water free of vegetation.  Alligators are a keystone species: Help maintain the structure and function of the communities where it is found. Help maintain the structure and function of the communities where it is found.

4.  Biological communities differ in the types and numbers of species they contain and the ecological roles those species play. Species diversity= species richness:  the number of different species it contains  species evenness:  combined with the abundance of individuals within each of those species

5. Species Diversity and Niche Structure  Niche structure: how many potential ecological niches occur, how they resemble or differ, and how the species occupying different niches interact.  Geographic location: species diversity is highest in the tropics and declines as we move from the equator toward the poles.

6. TYPES OF SPECIES  Native, nonnative, indicator, keystone, and foundation species play different ecological roles in communities.

7. Case Study: Species Diversity on Islands  MacArthur and Wilson proposed the species equilibrium model or theory of island biogeography in the 1960’s.  Model projects that at some point the rates of immigration and extinction should reach an equilibrium based on:  Island size & Distance to nearest mainland

8. SPECIES INTERACTIONS: COMPETITION AND PREDATION  Species can interact through competition, predation, parasitism, mutualism, and commensalism.  Some species evolve adaptations that allow them to reduce or avoid competition for resources with other species (resource partitioning).

9. Why do species compete? If two different species compete it is called _______ competition. Interspecific If two of the same species compete it is called _______ competition. Intraspecific If competition is intense, what must the less competitive species do? What is resource partitioning?

10. Resource Partitioning  Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion of the spruce tree and by consuming somewhat different insect species. Figure 7-7

11. PREDATION  Some prey escape their predators or have outer protection, some are camouflaged, and some use chemicals to repel predators. Figure 7-8

12. SPECIES INTERACTIONS: PARASITISM, MUTUALISM, AND COMMENSALIM  Parasitism occurs when one species feeds on part of another organism. +, -  In mutualism, two species interact in a way that benefits both. +, +  Commensalism is an interaction that benefits one species but has little, if any, effect on the other species. +, 0

13. Parasites: Sponging Off of Others  Although parasites can harm their hosts, they can promote community biodiversity. Some parasites live in host (micororganisms, tapeworms). Some parasites live in host (micororganisms, tapeworms). Some parasites live outside host (fleas, ticks, mistletoe plants, sea lampreys). Some parasites live outside host (fleas, ticks, mistletoe plants, sea lampreys). Some have little contact with host (dump-nesting birds like cowbirds, some duck species) Some have little contact with host (dump-nesting birds like cowbirds, some duck species)

14. Mutualism: Win-Win Relationship  Two species can interact in ways that benefit both of them. Figure 7-9

15. Commensalism: Using without Harming  Some species interact in a way that helps one species but has little or no effect on the other. Figure 7-10

16. Indicator Species: Biological Smoke Alarms  Species that serve as early warnings of damage to a community or an ecosystem. Presence or absence of trout species because they are sensitive to temperature and oxygen levels. Presence or absence of trout species because they are sensitive to temperature and oxygen levels. Are often amphibians, Why? Are often amphibians, Why?

17. Case Study: Why are Amphibians Vanishing?  Frogs serve as indicator species because different parts of their life cycles can be easily disturbed. Figure 7-3

18. Case Study: Why are Amphibians Vanishing?  Habitat loss and fragmentation.  Prolonged drought.  Pollution.  Increases in ultraviolet radiation.  Parasites.  Viral and Fungal diseases.  Overhunting.  Natural immigration or deliberate introduction of nonnative predators and competitors.

19. What does richness refer to? A. The number of individuals of each species B. The number of different species C. The number of edge effects D. The number of ecotones E. The number of different communities

20. Prey are least likely to defend themselves against predators by A. camouflage B. acute senses of sight and smell C. protective shells D. pursuit and ambush E. warning and ambush

21. Interspecific competition can be avoided by A. Eating at different times B. Resource partitioning C. Character displacement D. All of the above E. None of these answers

22. All of the following are ectoparasites except A. Fleas and ticks B. Mosquitoes C. Mistletoe D. Tapeworms E. Athletes foot

23. Species whose roles in an ecosystem are much more important than their abundance would suggest, are called A. Nonnative species B. Native species C. Keystone species D. Specialist species E. Generalist species

24. Keystone Species: Major Players  Keystone species help determine the types and numbers of other species in a community thereby helping to sustain it. Figures 7-4 and 7-5

25. Foundation Species: Other Major Players  Expansion of keystone species category.  Foundation species can create and enhance habitats that can benefit other species in a community. Elephants push over, break, or uproot trees, creating forest openings promoting grass growth for other species to utilize. Elephants push over, break, or uproot trees, creating forest openings promoting grass growth for other species to utilize.

26. ECOLOGICAL STABILITY AND SUSTAINABILITY  Many species play a role in ecosystems  Can keystone species be top predators?  Can they be decomposers?

27. How Would You Vote?  Do we have an ethical obligation to protect shark species from premature extinction and treat them humanely? No. It's impractical to force international laws on individual fishermen that are simply trying to feed their families with the fishing techniques that they have. No. It's impractical to force international laws on individual fishermen that are simply trying to feed their families with the fishing techniques that they have. Yes. Sharks are an important part of marine ecosystems. They must be protected and, like all animals, they should be humanely treated. Yes. Sharks are an important part of marine ecosystems. They must be protected and, like all animals, they should be humanely treated.

28. COMMUNITY STRUCTURE AND SPECIES DIVERSITY  Biological communities differ in their structure and physical appearance. Figure 7-2

29. ECOLOGICAL SUCCESSION: COMMUNITIES IN TRANSITION  New environmental conditions allow one group of species in a community to replace other groups.  Ecological succession: the gradual change in species composition of a given area Primary succession: the gradual establishment of biotic communities in lifeless areas where there is no soil or sediment. Primary succession: the gradual establishment of biotic communities in lifeless areas where there is no soil or sediment. Secondary succession: series of communities develop in places containing soil or sediment. Secondary succession: series of communities develop in places containing soil or sediment.

30. Primary succession begins with an essentially lifeless are where there is no soil in a terrestrial ecosystem What are the steps involved? 1)Pioneer species 2)Early successional plants 3)Mid-successional plants 4)Late successional plant Figure 7-11

31. Secondary succession begins in an area where the natural community has been disturbed. What 3 factors control the rate at which ecological succession takes place? 1)Facilitation2)Inhibition3)Tolerance Figure 7-12

32. What are the 3 aspects of stability or sustainability in living systems? A system that resists being disturbed or altered is said to have _____or _____. Inertia or persistence A population that can keep its numbers within limits imposed by resources shows _____. Constancy A system that is able to repair damage after a moderate external disturbance shows ______. Resilience

33. ECOLOGICAL STABILITY AND SUSTAINABILITY  Having many different species appears to increase the sustainability of many communities.  Human activities are disrupting ecosystem services that support and sustain all life and all economies.

34. A B C D E Which letter represents the stage in which shrubs grow? Which letter represents the start of secondary ecological succession? Which letter represents a mature forest of hardwoods? Which letter represents the step in which perennial weeds and grasses are plentiful? Which letter represents the stage in which the land can support trees, shrubs, weeds, and grasses?

35. Population biologists are concerned about introduced species such as the zebra mussel in North America because a. Their removal from their native habitat has a negative impact b. Predators of the introduced species often overpopulate because of the influx of the introduced species c. The introduced species compete for resources more effectively than native species d. Introduced species often become endangered in a new habitat e. Their introduction will require more land to be protected

36. Which of the following is the best example of a keystone species a. Sea Otter b. Sea Urchin c. Tree Frog d. Spotted Owl e. Snail Darter

37. Where is most of the world’s biodiversity? A. high-latitude forests B. Middle-latitude forests C. Low-latitude forests D. Polar grasslands E. Tundra

38. How long does it take natural processes to produce fertile soil. A. Weeks to months B. Months to years C. Decades to a few centuries D. Several centuries to several thousands of years E. Several thousand years to millions of years

39. The tropical rain forest is characterized by all of the following except high A. Diversity B. Resilience C. Inertia D. Constancy E. Persistence

40. Ecologists would consider all of the following to be natural disturbances except A. Droughts B. Floods C. Deforestation D. Fires E. Frost