Chapter 6 Part 1

1. Chapter 6Part 1 Species Interactions and Community Ecology

2. Zebra Mussels Invade the Great Lakes • Polluted waters Great Lakes became cleaner after the Clean Water Act of 1970 – used again for recreation and fishing • Zebra mussel arrived, native to western Asia and eastern Europe. • Larval stage is well adapted for long-distance dispersal, and it encountered none of the predators, competitors, and parasites it was used to

3. Zebra Mussels (continued) • Zebra mussels can • clog up water intake pipes • damage boat engines, docks, and fishing gear • sink buoys that ships use for navigation • Zebra mussels also have severe impacts on the ecological systems they invade • take large quantities of food (phytoplankton) needed by native molluscs for food • It is being displaced by the quagga mussel, which has a larger niche than even the zebra mussel.

4. Species Interactions • Most common interactions • Competition • Predation • Parasitism • Herbivory • Mutualism

5. Competition • Occurs when resources are limited • Intraspecific competition – between members of the same species • Limits population growth • Interspecific competion – among members of at least 2 different species • Affects composition (what is in) of communities *interstate runs between more than one state

6. Competitive Exclusion • One species is a very effective competitor • Excludes another species from a resource completely • Example: zebra mussel outcompeted the native mussel in the Great Lakes

7. Species Coexistence • When one species does not fully exclude another from resources • State of equilibrium – population size of each species remains constant • Species that use the same resources can minimize competition

8. Minimizing Competition • Use only a portion of the total array of resources (niche) that they are capable of using • Full niche of a species is called its fundamental niche • An individual that plays only part of its role because of competition or other species interactions - displaying a realized niche. (page 143, Fig. 6.2)

9. Minimizing Competition (continued) • Resource partitioning - competing species may evolve to use slightly different resources or to use their shared resources in different ways. • Over time, character displacement may occur as they evolve physical characteristics that reflect their use of a specific portion of the resource • Natural Selection!

10. Exploitative Interactions • Exploitation occurs when one member of an interaction exploits or uses another for its own gain. • Examples: • Predation • Parasitism • Herbivory

11. Predation • Predation - an individual of one species hunts, captures, kills, and consumes an individual of another species, its prey. • Predation can sometimes drive population dynamics, causing cycles in population sizes. • Better predators will leave more and healthier offspring – making them better hunters. • Prey species - evolve defense mechanisms

12. Parasitism • Parasitism - the parasite, depends on the host, for nourishment or some other benefit while doing the host harm. • Many parasites live in close contact with their hosts, such as tapeworms, ticks, and lamprey. • Other types of parasites are free-living and come into contact with their hosts only infrequently (e.g., nest parasites such as cuckoos and cowbirds).

13. Parasitism (contiued) • Some parasites cause little harm, but others may kill their hosts • Examples: • Parasitic wasps • Lay eggs on caterpillars • Larvae burrow into and eat caterpillar’s tissue • Larvae turn into wasps that fly out of dead cateripillar • Sea lampreys (see handout)

14. Herbivory • Herbivores exploit (use) plants. • Herbivory occurs when animals feed on the tissues of plants • Plant defenses: • Production of toxic chemicals • Thorns, spines, irritating hairs • Other insects working with plant to attack the predators (ants protect some plants)

15. Mutualism • Mutualists help one another. • Mutualism - two or more species benefit from interaction with one another. • Many mutualistic relationships occur between organisms that live in close physical contact; this is called symbiosis. • Bees and flowers engage in mutualism in the process of pollination.

16. Use Your Book! • Use your text to list examples of mutualism – you have 5 minutes.

17. Commensalism • Some interactions have no effect on some participants. • Commensalism occurs when one organism benefits and the other is unaffected. • Barnacles – barnacles attach to skin of whales and can be transported to new sources of food • Remora sharks – have an adhesive (sticky) disk on their head and can attach to whales. After the whale eats, the shark detaches and eats the leftovers!

18. Book Work! • Page 171, Testing Your Comprehension, numbers 1 – 3 • SAVE THIS PAPER! YOU WILL BE ADDING MORE TO IT!

19. Ecological Communities • Energy passes among trophic levels. • As organisms feed on one another - energy moves through the community from one trophic level to another. • Producers are the first trophic level. • Examples: • Grasses, algae, chemosynthetic bacteria

20. Consumers • Second trophic level - primary consumers • Most of them consume plants and are called herbivores(deer or grasshoppers eat grass) • Third trophic level - secondary consumers • prey on primary consumers (rodents eat grasshoppers that eat grass)

21. Consumers (continued) • Higher trophic levels –tertiary consumers • hawks eat rodents that eat grasshoppers that eat grass * Secondary and tertiary consumers are carnivores because they eat animals

22. Consumers (continued) • Animals that eat both plant and animal food are omnivores. • Detritivores (scavengers) and decomposers (break down) consume nonliving organic • These “eat” the dead material from all other trophic levels • Look at page 149, Fig. 6.10 • The arrow points to what is doing the “eating”

23. Rule of 10 • Think back to our Rule of 10 pyramid! • Only 10% of the usable energy is passed on. • The producers start with the most energy, and it decreases with every step up. • Being a vegetarian, rather than a meat-eater, decreases a person’s ecological footprint. Why? • Page 150, Weighing the Issues

24. Biomass • Biomass – organic material that makes up living organisms • Biomass energy – energy harnessed from plant and animal matter • The Rule of 10 applies to • Energy • amount of biomass/biomass energy • and number of organisms

25. Food Webs • Show feeding relationships and energy flow • Visual map • Shows the many paths by which energy passes among organisms as they consume one another. • Page 151, Fig. 6.12

26. With a Partner: 20 Minutes • Draw a food web that could be found in TN • Use colored pencils • Do not have to have elaborate drawings • Stick drawings (like Mrs. Alred’s drawings) are fine • Must include • Producer (10 points) • Primary consumer (10 points) • Secondary consumer (10 points) • Tertiary consumer (10 points) • Decomposer/Detritivore (10 points)

27. Keystone Species • Some organisms play bigger roles in communities than others. • keystone species - has a particularly strong or far-reaching impact • Examples: Large-bodied secondary or tertiary consumers (hawks, wolves, sharks) • Some keystone species physically modify the environment (beavers, prairie dogs, fungi)

28. Communities Respond to Disturbances • A community that resists change and remains stable is said to show resistance to the disturbance. • A community may show resilience, meaning that it changes in response to disturbance but later returns to its original state.

29. Succession Follows Severe Disturbance • If a disturbance eliminates all/most of the species in a community, the site will undergo a series of changes called succession. • Primary succession • Secondary succession

30. Primary Succession • Primary succession - a biotic community is built from scratch • 1) Pioneer species, such as lichens (fungi and algae), are the first to arrive. • 2) Lichens secrete acid, starting the process of soil formation. • 3) New, larger organisms arrive and pave the way for more new species, - a community becomes established.

31. Secondary Succession • Secondary succession -a disturbance dramatically alters an existing community but does not destroy all living things or all organic matter in the soil • Grasses • Shrubs • Saplings • Pines • Hardwoods Look at Page 155, Fig. 6.15

32. Book Work • Add this to your original paper of #s 1-3 • Page 170, TYC #s 4-6 • Due on Wednesday!

33. Invasive Species • a non-native organism that spreads, becomes dominant, and has potential to substantially alter a community. • controlling and eradicating invasive species are so difficult and expensive that preventive measures represent a much better investment.

34. Impact of Invasive Species • most cases - overall negative impacts on ecosystems • rare cases, non-native species like the honeybee provide important economic benefits to agriculture and ornamental crops

35. Ecological Restoration • Efforts to restore areas to a more pristine habitat • Restoration ecologists research the history of an area to understand its “presettlement” condition (before it was altered) • Time consuming and expensive , so it is better to protect natural landscapes from degradation

36. Ecological Restoration Projects • Great Plains and Midwest prairie restoration • Florida Everglades • 30 years, $7.8 billion • Provides drinking water, tourism, ecosystem services • Mesopotamian marshes • New effort – no access of funds allowed yet • Between Tigris and Euphrates Rivers in Iraq • Restore traditional lifestyles to former minorities forced out by Saddam Hussein