1. Ecology of Communities Types of Species Interactions

2. Species Interactions Close interaction between species.Close interaction between species. –Predation –Parasitism –Competition –Mutualism –Commensalism Tuesday 9/5/06 Pages 397-402 Section 21-1 Which community is most diverse? Why?

3. Predation Predators capture, kill, and consume prey.Predators capture, kill, and consume prey. –Predators are adapted to role. –Prey are adapted to survive predator Which species determines the number of the other? Tuesday 9/05/06 Pages 397-402 Section 21-1

4. Predation MimicryMimicry –Prey evolve defenses through natural selection. –Coloration mimics poisonous organism. –Warning coloration Why is the western King Snake not colored like the Arizona King Snake? Tuesday 9/05/06 Pages 397-402 Section 21-1

5. MimicryMimicry –Batesian mimicry One poisonous, one notOne poisonous, one not –Mullerian mimicry Both poisonousBoth poisonous

6. Predation Plant - HerbivorePlant - Herbivore Plants are defending against herbivory.Plants are defending against herbivory. –Thorns, spines, sticky hairs. –Secondary chemicals NicotineNicotine StrychnineStrychnine DigitalisDigitalis Poison oakPoison oak What animal group is the plant trying to discourage? Tuesday 9/05/06 Pages 397-402 Section 21-1

7. Parasitism Parasite is helped.Parasite is helped. Host is harmed.Host is harmed. –Ectoparsites –Endoparasites Why does a parasite usually not kill its host? Tuesday 9/05/06 Pages 397-402 Section 21-1

8. Mutualism Both species benefit.Both species benefit. LichensLichens –2 layers of fungi –Algae cells inside. –Algae is kept moist –Fungi get food. Are mutualism relationships species specific? Modern Biology Pages 397-402 Section 21-1

9. Commensalism One species benefits.One species benefits. One species is not effected.One species is not effected. –Lichens growing on a tree limb. –Cattle egrets and live stock. Modern Biology Pages 397-402 Section 21-1

10. Competition Results from fundamental niche overlap.Results from fundamental niche overlap. –Competitive exclusion. –When two species directly compete, one will go extinct. What, most likely, is being competed for in this study? Modern Biology Pages 397-402 Section 21-1

11. Competition Results from fundamental niche overlap.Results from fundamental niche overlap. –Character displacement –Competitors evolve to different niches. How does the Barn Owl and Red Tail Hawk demonstrate character displacement? Modern Biology Pages 397-402 Section 21-1

12. Competition Results from fundamental niche overlap.Results from fundamental niche overlap. –Resource partitioning. –Each competing species uses a portion of the resource. –Results in less competition between species. How does the Cape may Warbler differ from the rest of the warbler species? Modern Biology Pages 397-402 Section 21-1

13. Pages 397-402 Section 21-1 Review

14. Review

15. Fundamental nicheFundamental niche –Full range of interactions in ecosystem. –All potential resources –Theoretical niche as if no other organisms present Why is the realized niche shown above smaller than the fundamental niche? Modern Biology Pages 363-365 Key Words: Fundamental niche Realized niche How is a fundamental niche different from a realized niche?

16. Modern BiologyModern Biology Pages 371-372Pages 371-372 Ecology of Organisms Realized nicheRealized niche –All resources actually used. –Competition with other organisms limits fundamental niche. –Something less than the fundamental niche. Which species out competes the other species regarding niche?

17. Properties of Communities Modern Biology Pages 397-402 Section 21-1 Species richness.Species richness. –The total number of species in an ecosystem.

18. Properties of Communities Modern Biology Pages 397-402 Section 21-1 Species diversity.Species diversity. –The total number of species in an ecosystem. –Also accounts for the number of each species.

19. Patterns of Species Richness Modern Biology Pages 397-402 Section 21-1 Closer to the equator, the greater the richness.Closer to the equator, the greater the richness. Reasons why:Reasons why: –Older communities in tropics. –Stable climate –More available energy

20. Succession Modern Biology Pages 397-402 Section 21-1 Gradual regrowth of species after a disruption.Gradual regrowth of species after a disruption. Two types of succession:Two types of succession: –Primary (starts with pioneer species) –Secondary (occurs after disruption) FireFire FloodFlood StormStorm Human activityHuman activity FarmingFarming

21. Primary Succession Modern Biology Pages 397-402 Section 21-1 Starts slow due to lack of minerals.Starts slow due to lack of minerals. –Pioneer species first appear. –Eventually soil is produced. –Grasses appear. –Shrubs appear. –Finally trees appear.

22. Secondary Succession Modern Biology Pages 397-402 Section 21-1 Disturbance leaves just soil intact.Disturbance leaves just soil intact. Secondary succession starts with grasses.Secondary succession starts with grasses. A stable climax community results.A stable climax community results. Some communities never reach stable climax community.Some communities never reach stable climax community.

23. Energy Transfers in Communities

24. Producers Monday 3/23/03 Pages 415-419 Section 22-1 Producers use energy to produce organic molecules.Producers use energy to produce organic molecules. AutotrophsAutotrophs –Use energy to produce carbohydrates. –Most are photosynthetic. –Few are chemosynthetic.

25. Measuring Productivity Monday 3/23/03 Pages 415-419 Section 22-1 Gross Primary productivity:Gross Primary productivity: –The rate at which producers capture energy. –Equal to all of the carbohydrates produced using photosynthesis.

26. Measuring Productivity Monday 3/23/03 Pages 415-419 Section 22-1 Net Primary Productivity.Net Primary Productivity. –All organic material in an ecosystem is referred to as biomass. –All stored energy in the ecosystem. –Rate at which biomass accumulates is NPP. –GPP - carbohydrates used for living.

27. Consumers Monday 3/23/03 Pages 415-419 Section 22-1 Consumers are heterotrophs.Consumers are heterotrophs. Obtain energy by consuming organic molecules.Obtain energy by consuming organic molecules. HerbivoresHerbivores CarnivoreCarnivore OmnivoreOmnivore DetritivoreDetritivore DecomposersDecomposers

28. Energy Flow Monday 3/23/03 Pages 415-419 Section 22-1 Energy is transferred from organism to organism.Energy is transferred from organism to organism. Trophic level refers to feeding position in communityTrophic level refers to feeding position in community Trophic levels:Trophic levels: –1st level = producers –2nd level = herbivores –3rd level = carnivore –4th level = second carnivore

30. Food Chains Monday 3/23/03 Pages 415-419 Section 22-1 A single pathway of energy through the ecosystem.A single pathway of energy through the ecosystem. Approximately 10% of energy is preserved in each transfer.Approximately 10% of energy is preserved in each transfer. 5% of sun’s energy is preserved in the producers.5% of sun’s energy is preserved in the producers.

31. Food Webs Monday 3/23/03 Pages 415-419 Section 22-1 Several food chains interlinked.Several food chains interlinked. Better shows energy flow in an ecosystem.Better shows energy flow in an ecosystem.

32. Food Webs Monday 3/23/03 Pages 415-419 Section 22-1 Several food chains interlinked.Several food chains interlinked. Better shows energy flow in an ecosystem.Better shows energy flow in an ecosystem.

33. Biogeochemical Cycle Wednesday 3/25/03 Pages 420-423 Section 22-2 Energy flows through an ecosystem.Energy flows through an ecosystem. Water and minerals recycle in the ecosystem.Water and minerals recycle in the ecosystem. –Water Nitrogen –Minerals Calcium –Carbon Phosphorus

34. Water Cycle Wednesday 3/25/03 Pages 420-423 Section 22-2 Availability of water determines productivity.Availability of water determines productivity. –Evaporation –Transpiration –Precipitation 90% of water that evaporates in ecosystem passes through plants.90% of water that evaporates in ecosystem passes through plants.

35. Carbon Cycle Wednesday 3/25/03 Pages 420-423 Section 22-2 Carbon cycle is composed of two processes:Carbon cycle is composed of two processes: –Photosynthesis –Respiration Autotrophs do ____.Autotrophs do ____. Heterotrophs do ____.Heterotrophs do ____. Detritivores do ____.Detritivores do ____. Decomposers do ____.Decomposers do ____.

36. Nitrogen Cycle Wednesday 3/25/03 Pages 420-423 Section 22-2 All living organisms need nitrogen (N 2 )All living organisms need nitrogen (N 2 ) 78% of the atmosphere is composed of N 2.78% of the atmosphere is composed of N 2. –Only usable to a few organisms. –Nitrogen fixation –Nitrogen fixation bacteria. Breakdown of organic material results in ammonia.Breakdown of organic material results in ammonia. Nitrogen is returned to the atmosphere.Nitrogen is returned to the atmosphere.

37. Species-Area effect Modern Biology Pages 397-402 Section 21-1 Larger areas support higher degree of richness.Larger areas support higher degree of richness. Example: islandsExample: islands

38. Community Stability Modern Biology Pages 397-402 Section 21-1 How well a community with stands change.How well a community with stands change. Species richness improves stability.Species richness improves stability. ExperimentExperiment –Grass plots