1. Copyright © 2009 Pearson Education, Inc. PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Chapter 37 Communities and Ecosystems Lecture by Brian R. Shmaefsky

2. Copyright © 2009 Pearson Education, Inc. COMMUNITY STRUCTURE AND DYNAMICS

3. Copyright © 2009 Pearson Education, Inc. 37.1 A community includes all the organisms inhabiting a particular area  Biological community –An assemblage of populations living close enough together for potential interaction –Described by its species composition  Boundaries of the community vary with research questions –Can be a pond –Can be the intestinal microbes of a pond organism

4. Copyright © 2009 Pearson Education, Inc.  Interspecific interactions –Relationships with other species in the community  Interspecific competition –Two different species compete for the same limited resource –Squirrels and black bears –Compete for acorns 37.2 Interspecific interactions are fundamental to community structure

6. Copyright © 2009 Pearson Education, Inc. 37.3 Competition may occur when a shared resource is limited  Ecological niche –Sum of an organism’s use of biotic and abiotic resources –Interspecific competition occurs when the niches of two populations overlap  Competition lowers the carrying capacity of competing populations

7. Copyright © 2009 Pearson Education, Inc.  Interspecific competition between orange-crowned warbler and Virginia’s warbler 37.3 Competition may occur when …….

10. Copyright © 2009 Pearson Education, Inc. 37.4 Mutualism benefits both partners  Reef-building corals require mutualism –Photosynthetic dinoflagellates –Live in the cells of each coral polyp –Produce sugars used by the polyps –Provide at least half of the energy used by the coral animals Video: Clownfish and Anemone

12. Copyright © 2009 Pearson Education, Inc. 37.5 EVOLUTION CONNECTION: Predation leads to diverse adaptations in prey species  Predation benefits the predator but kills the prey  Prey adapt using protective strategies –Camouflage –Mechanical defenses –Chemical defenses Video: Seahorse Camouflage

15. Copyright © 2009 Pearson Education, Inc. 37.6 EVOLUTION CONNECTION: Herbivory leads to diverse adaptations in plants  Herbivory is not usually fatal –Plants must expend energy to replace the loss  Plants have numerous defenses against herbivores –Spines and thorns –Chemical toxins

16. Copyright © 2009 Pearson Education, Inc.  Herbivores and plants undergo coevolution –A change in one species acts as a new selective force on another –Poison-resistant caterpillars seem to be a strong selective force for Passiflora plants 37.6 EVOLUTION CONNECTION: Herbivory leads to diverse adaptations in plants

17. Eggs Sugar deposits

18. Copyright © 2009 Pearson Education, Inc. 37.7 Parasites and pathogens can affect community composition  A parasite lives on or in a host from which it obtains nourishment –Internal parasites include nematodes and tapeworms –External parasites include mosquitoes and ticks  Pathogens are disease-causing parasites –Pathogens can be bacteria, viruses, fungi, or protists

20. Copyright © 2009 Pearson Education, Inc.  Non-native pathogens can have rapid and dramatic impacts –American chestnut devastated by chestnut blight protist –A fungus-like pathogen currently causing sudden oak death on the West Coast  Non-native pathogens can cause a decline of the ecosystem 37.7 Parasites and pathogens can affect community composition

21. Copyright © 2009 Pearson Education, Inc. 37.8 Trophic structure is a key factor in community dynamics  Trophic structure –A pattern of feeding relationships consisting of several different levels  Food chain –Sequence of food transfer up the trophic levels

22. Copyright © 2009 Pearson Education, Inc.  Producers –Support all other trophic levels –Autotrophs –Photosynthetic producers –Plants on land –Cyanobacteria in water 37.8 Trophic structure is a key factor in community dynamics

23. Copyright © 2009 Pearson Education, Inc.  Consumers –Heterotrophs –Primary consumers –Secondary consumers –Tertiary consumers –Quaternary consumers  Detritivores and decomposers –Derive energy from dead matter and wastes 37.8 Trophic structure is a key factor in community dynamics Video: Shark Eating a Seal

24. Plant A terrestrial food chain Producers Phytoplankton An aquatic food chain

25. Plant A terrestrial food chain Producers Phytoplankton An aquatic food chain Primary consumers Grasshopper Zooplankton

26. Plant A terrestrial food chain Producers Phytoplankton An aquatic food chain Primary consumers Grasshopper Zooplankton Secondary consumers Mouse Herring

27. Plant A terrestrial food chain Producers Phytoplankton An aquatic food chain Primary consumers Grasshopper Zooplankton Secondary consumers Mouse Herring Snake Tuna Tertiary consumers

28. Plant A terrestrial food chain Producers Phytoplankton An aquatic food chain Primary consumers Grasshopper Zooplankton Secondary consumers Mouse Herring Snake Tuna Tertiary consumers Hawk Killer whale Quaternary consumers Trophic level

29. Copyright © 2009 Pearson Education, Inc. 37.9 Food chains interconnect, forming food webs  Food web –A network of interconnecting food chains

30. Producers (plants) Primary consumers Secondary and primary consumers Tertiary and secondary consumers Quaternary, tertiary, and secondary consumers

31. Copyright © 2009 Pearson Education, Inc. 37.11 Keystone species have a disproportionate impact on diversity  Keystone species –A species whose impact on its community is larger than its biomass or abundance indicates –Occupies a niche that holds the rest of its community in place

32. Keystone absent

36. Copyright © 2009 Pearson Education, Inc. 37.12 Disturbance is a prominent feature of most communities  Disturbances –Events that damage biological communities –Storms, fire, floods, droughts, overgrazing, or human activity –The types, frequency, and severity of disturbances vary from community to community

37. Copyright © 2009 Pearson Education, Inc.  Communities change drastically following a severe disturbance  Ecological succession –Colonization by a variety of species –A success of change gradually replaces other species 37.12 Disturbance is a prominent feature of most communities

38. Copyright © 2009 Pearson Education, Inc.  Primary succession –Begins in a virtually lifeless area with no soil  Secondary succession –When a disturbance destroyed an existing community but left the soil intact 37.12 Disturbance is a prominent feature of most communities

39. Time Shrubs Annual plants Perennial plants and grasses Softwood trees such as pines Hardwood trees

40. Copyright © 2009 Pearson Education, Inc. 37.13 CONNECTION: Invasive species can devastate communities  Introduction of rabbits in Australia

41. Key Frontier of rabbit spread Origin: 1860 600 Km Australia 1910 1980 1910 1920 1890 1880 1870 1900

43. Copyright © 2009 Pearson Education, Inc. ECOSYSTEM STRUCTURE AND DYNAMICS

44. Copyright © 2009 Pearson Education, Inc. 37.14 Ecosystem ecology emphasizes energy flow and chemical cycling  Ecosystem –All the organisms in a community as well as the abiotic environment  Components of ecosystems –Energy flow –Passage of energy through the ecosystem –Chemical cycling –Transfer of materials within the ecosystem

45. Copyright © 2009 Pearson Education, Inc.  A terrarium has the components of an ecosystem 37.14 Ecosystem ecology emphasizes energy flow and chemical cycling

46. Energy flow Light energy Chemical energy Chemical elements Heat energy Bacteria and fungi Chemical cycling

47. Copyright © 2009 Pearson Education, Inc. 37.15 Primary production sets the energy budget for ecosystems  Primary production –The amount of solar energy converted to chemical energy –Carried out by producers –Produces biomass –Amount of living organic material in an ecosystem

48. Copyright © 2009 Pearson Education, Inc.  Primary production of different ecosystems 37.15 Primary production sets the energy budget for ecosystems

49. Open ocean Estuary Algal beds and coral reefs Desert and semidesert scrub Tundra Temperate grassland Cultivated land Boreal forest (taiga) Savanna Temperate deciduous forest Tropical rain forest 0 500 Average net primary productivity (g/m 2 /yr) 1,000 1,500 2,5002,000

50. Copyright © 2009 Pearson Education, Inc. 37.16 Energy supply limits the length of food chains  A pyramid of production –Illustrates the cumulative loss of energy transfer in a food chain

51. 1,000,000 kcal of sunlight 10 kcal 100 kcal 1,000 kcal 10,000 kcal Producers Primary consumers Secondary consumers Tertiary consumers

52. Copyright © 2009 Pearson Education, Inc. 37.17 CONNECTION: A production pyramid explains why meat is a luxury for humans  The dynamics of energy flow apply to the human population

53. Producers Primary consumers Secondary consumers Human meat-eaters Cattle Corn Human vegetarians Trophic level

54. Copyright © 2009 Pearson Education, Inc. 37.18 Chemicals are cycled between organic matter and abiotic reservoirs  Ecosystems are supplied with a continual influx of energy –Sun –Earth’s interior  Life also depends on the recycling of chemicals –Organisms acquire chemicals as nutrients and lose chemicals as waste products

55. Copyright © 2009 Pearson Education, Inc.  Biogeochemical cycles –Cycle chemicals between organisms and the Earth –Can be local or global  Decomposers play a central role in biogeochemical cycles 37.18 Chemicals are cycled between organic matter and abiotic reservoirs

56. Consumers Geologic processes Producers Decomposers Nutrients available to producers Abiotic reservoir 4 1 2 3

57. Copyright © 2009 Pearson Education, Inc. 37.19 The carbon cycle depends on photosynthesis and respiration  Carbon is the major ingredient of all organic molecules  The return of CO 2 to the atmosphere by respiration closely balances its removal by photosynthesis  The carbon cycle is affected by burning wood and fossil fuels

58. Photosynthesis Decomposers (soil microbes) Cellular respiration Detritus 4 1 2 3 5 Plants, algae, cyanobacteria Primary consumers Higher-level consumers Burning CO 2 in atmosphere Plant litter; death Wastes; death Decomposition Wood and fossil fuels

59. Copyright © 2009 Pearson Education, Inc. 37.20 The phosphorus cycle depends on the weathering of rock  Organisms require phosphorus for nucleic acids, phospholipids, and ATP –Plants absorb phosphate ions in the soil and build them into organic compounds –Phosphates are returned to the soil by decomposers –Phosphate levels in aquatic ecosystems are typically low enough to be a limiting factor

60. Animals 1 Plants Detritus Decomposers in soil Decomposition Phosphates in rock Weathering of rock Runoff Assimilation Phosphates in solution Phosphates in soil (inorganic) Precipitated (solid) phosphates Rock Uplifting of rock 6 3 2 4 5

61. Copyright © 2009 Pearson Education, Inc. 37.21 The nitrogen cycle depends on bacteria  Nitrogen is an essential component of proteins and nucleic acids  Nitrogen has two abiotic reservoirs –Air –Soil  Nitrogen fixation converts N 2 to nitrogen used by plants –Carried out by some bacteria and cyanobacteria

62. Nitrogen (N 2 ) in atmosphere 8 Plant Animal Assimilation by plants Organic compounds Organic compounds Death; wastes Denitrifiers Nitrates in soil (NO 3 – ) Detritus Decomposers Decomposition Nitrifying bacteria Ammonium (NH 4 + ) in soil Nitrogen fixation Nitrogen fixation Nitrogen-fixing bacteria in root nodules Free-living nitrogen-fixing bacteria and cyanobacteria 6 1 2 7 4 3 5

63. Copyright © 2009 Pearson Education, Inc. 37.22 CONNECTION: Ecosystem alteration can upset chemical cycling  Chemical cycling in an ecosystem depends on –The web of feeding –Relationships between plants, animals, and detritivores –Geologic processes  Altering an environment can cause severe losses in chemical cycling –Erosion –Acid rain

66. Deforested Completion of tree cutting Control 1968 1967 1966 1965 80.0 Nitrate concentration in runoff (mg/L) 60.0 40.0 20.0 4.0 3.0 2.0 1.0 0

67. Copyright © 2009 Pearson Education, Inc. 37.23 TALKING ABOUT SCIENCE: David Schindler talks about the effects of nutrients on freshwater ecosystems  Major changes in terrestrial ecosystems disrupt chemical cycling  These changes can increase nutrients in aquatic ecosystems –Algal and cyanobacteria blooms –Eutrophication

68. Copyright © 2009 Pearson Education, Inc.  The most serious current threats –Acid precipitation –Changes in land use –Climate warming 37.23 TALKING ABOUT SCIENCE: David Schindler talks about the effects of nutrients on freshwater ecosystems Video: Cyanobacteria (Oscillatoria)

71. Decomposers Producer Energy flow Chemical cycling Herbivore (primary consumer) Carnivore (secondary consumer)

72. chemical elements Ecosystems involve the processes of in which makes a from are incorporated by is converted by to chemical energy of into components of detritivores return elements to which pass through one-way trip solar energy to chemical energy to heat organic molecules (a)(b) (c) (d)(e) (f)

74. Copyright © 2009 Pearson Education, Inc. You should now be able to 1.Describe the characteristics of a community 2.Explain how interspecific interactions affect the dynamics of populations 3.Describe the trophic structure of a community 4.Explain how species diversity is measured 5.Describe the role of environmental disturbance on ecological succession 6.Explain energy and nutrient cycling in ecosystems