1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 37 Communities and Ecosystems

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dining In Community structure and function depend on the interactions among organisms – Example: Apanteles glomeratus wasp, Pieris rapae butterfly, and other wasps Ecosystem structure and function depend on the interactions of the community with its abiotic environment

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings STRUCTURAL FEATURES OF COMMUNITIES 37.1 A community includes all the organisms inhabiting a particular area Biological community: an assemblage of all the populations of organisms living close enough together for potential interaction Key characteristics of a community – Species diversity: variety of different kinds of organisms Species richness Relative abundance

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – Dominant species – Response to disturbances – Trophic structure: feeding relationships among species

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.2 Competition may occur when a shared resource is limited Interspecific competition may play a major role in structuring a community – Two species competing for the same limited resource – May inhibit growth of one or both species

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Competitive exclusion principle – Two species cannot coexist in a community if their niches are identical Niche: species' total use of biotic and abiotic resources – Two possible results Less competitive species will be driven to local extinction Resource partitioning may evolve

12. LE 37-2a

13. LE 37-2b

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.3 Predation leads to diverse adaptations in both predator and prey Predation is an interaction between species in which predator kills and eats prey Adaptations of both tend to be refined through natural selection – Camouflage – Chemical defense Video: Seahorse Camouflage Video: Seahorse Camouflage

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

17. – Batesian mimicry Palatable species mimics an unpalatable model – Mullerian mimicry Two unpalatable species mimic each other

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.4 Predation can maintain diversity in a community Keystone species – Exerts strong control on community structure because of its ecological niche Keystone predator – May maintain community diversity by reducing numbers of the strongest competitors – Removal can cause major changes in community dynamics

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.5 Herbivores and the plants they eat have various adaptations Herbivores are animals that eat plants or algae – Have adaptations for locating and eating vegetation Plants have evolved defenses against herbivores – Toxic chemicals – Physical defenses (spines, thorns)

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some herbivore-plant interactions illustrate coevolution – Reciprocal evolutionary adaptations – Change in one species acts as a new selective force on another species

25. LE 37-5 Eggs Sugar deposits

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.6 Symbiotic relationships help structure communities Symbiotic relationship: interaction between two or more species that live in direct contact – Parasitism Parasite lives on or near its host Parasite obtains nourishment at the expense of host Includes pathogens that may inflict lethal harm on host

28. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Commensalism – One species benefits without significantly affecting the other – Few absolute cases documented Mutualism – Both partners benefit

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Video: Clownfish and Anemone Video: Clownfish and Anemone

31. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.7 Disturbance is a prominent feature of most communities Disturbances are characteristic of most biological communities – Events such as fire, storms, floods – Damage communities – Remove organisms from communities – Alter the availability of resources – Can have positive effects

32. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ecological succession is a transition in community species composition following a major disturbance – Primary succession: gradual colonization of barren rocks – Secondary succession: occurs after a disturbance has destroyed a community but left the soil intact

33. LE 37-7 Retreating glacier with moraine in the foreground Dryas stage Spruce starting to appear in the alder and cottonwood forest Spruce and hemlock forest

34. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings TALKING ABOUT SCIENCE 37.8 Fire specialist Max Moritz discusses the role of fire in ecosystems Dr. Max Moritz studies fire in chaparral ecosystems Fire is a key abiotic factor in many ecosystems – Important in nutrient cycling – Creates conditions for regeneration of many plants Dr. Moritz hopes to help people coexist with cycles of weather, vegetation, growth, and fire

37. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.9 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 – Moves chemical nutrients and energy

38. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Producers – Autotrophs that support all other trophic levels – Plants on land – In water, mainly photosynthetic protists and cyanobacteria Primary consumers – Herbivores that eat plants, algae, or phytoplankton

39. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Secondary, tertiary, and quaternary consumers – Eat consumers from the level below them Detritivores (decomposers) – Animal scavengers, fungi, and prokaryotes – Derive energy from detritus produced at all trophic levels – Decomposition is essential for recycling nutrients in ecosystems Video: Shark Eating Seal Video: Shark Eating Seal

40. LE 37-9 Trophic level Quaternary consumers Tertiary consumers Hawk Snake Mouse Grasshopper Plant A terrestrial food chainAn aquatic food chain Producers Primary consumers Secondary consumers Phytoplankton Zooplankton Herring Tuna Killer whale

41. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.10 Food chains interconnect, forming food webs A food web is a more realistic view of trophic structure – Consumers usually eat more than one type of food – Each food type is consumed by more than one type of consumer

42. LE 37-10 Quaternary, tertiary, and secondary consumers Tertiary and secondary consumers Secondary and primary consumers Primary consumers Producers (plants)

43. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ECOSYSTEM STRUCTURE AND DYNAMICS 37.11 Ecosystem ecology emphasizes energy flow and chemical cycling An ecosystem consists of all the organisms in a community and the abiotic factors with which they interact Ecosystem dynamics involve two processes – Energy flow through the components of the ecosystem – Chemical cycling within the ecosystem

44. LE 37-11 Energy flow Light energy Chemical cycling Chemical energy Chemical elements Heat energy

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.12 Primary production sets the energy budget for ecosystems Primary production: amount of solar energy converted by producers to chemical energy in biomass – Biomass: amount of organic material in an ecosystem – Net primary production: amount of biomass produced minus amount used by producers in cellular respiration – Varies greatly among ecosystems

46. LE 37-12 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 05001,0001,5002,0002,500 Average net primary productivity (g/m 2 /yr)

47. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.13 Energy supply limits the length of food chains Only about 10% of the energy stored at each trophic level is available to the next level – Pyramid of production shows loss of energy from producers to higher trophic levels – Amount of energy available to top-level consumers is relatively small Most food chains have only three to five levels

48. LE 37-13 Tertiary consumers Secondary consumers Primary consumers Producers 10 kcal 100 kcal 1,000 kcal 10,000 kcal 1,000,000 kcal of sunlight

49. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CONNECTION 37.14 A production pyramid explains why meat is a luxury for humans Human meat or fish eaters are tertiary or quaternary consumers Humans eating grain have ten times more energy available than when they process the same amount of grain through meat Using land to raise animals consumes more resources than using the land to cultivate crops

50. LE 37-14 Trophic level Secondary consumers Primary consumers Human vegetarians Producers Corn Cattle Human meat-eaters

51. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.15 Chemicals are recycled between organic matter and abiotic reservoirs Biogeochemical cycles – Cycle nutrients through both biotic and abiotic components – Can be local or global

52. LE 37-15 Consumers Producers Nutrients available to producers Detritivores Abiotic reservoir

53. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.16 Water moves through the biosphere in a global cycle – Solar energy drives the global water cycle – Precipitation – Evaporation – Transpiration – Water cycles between the land, oceans, and atmosphere – Forest destruction and irrigation affect the water cycle

54. LE 37-16 Solar energy Net movement of water vapor by wind Evaporation from ocean Precipitation over ocean Evaporation and transpiration from land Transport over land Precipitation over land Percolation through soil Runoff and groundwater

55. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.17 The carbon cycle depends on photosynthesis and respiration Carbon cycles through the atmosphere, fossil fuels, and dissolved carbon in oceans – Taken from the atmosphere by photosynthesis – Used to make organic molecules – Decomposed by detritivores – Returned to the atmosphere by cellular respiration Burning of wood and fossil fuels is raising the level of CO 2 in the atmosphere

56. LE 37-17 Cellular respiration Photosynthesis CO 2 in atmosphere Burning of fossil fuels and wood Primary consumers Higher-level consumers Detritus Carbon compounds in water Decomposition

57. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.18 The nitrogen cycle relies heavily on bacteria Atmospheric N 2 is not available to plants – Soil bacteria convert gaseous N 2 to usable ammonium (NH 4 + ) and nitrate (NO 3 - ) – Some NH 4 + and NO 3 - are made by chemical reactions in the atmosphere Human activity is altering nitrogen cycle balance in many areas – Sewage treatment and fertilization

58. LE 37-18 Nitrogen in atmosphere (N 2 ) Nitrogen fixation Nitrogen-fixing bacteria in root nodules of legumes Detritivores Decomposition Assimilation by plants Denitrifying bacteria Nitrifying bacteria Nitrates (NO 3 – ) Nitrogen-fixing soil bacteria Ammonium (NH 4  )

59. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 37.19 The phosphorus cycle depends on the weathering of rock Phosphorus and other soil minerals are recycled locally Weathering of rock adds PO 4 3- to soil – Slow process makes amount of phosphorus available to plants low Human activity has created phosphate pollution of water

60. LE 37-19 Rain Plant uptake of PO 4 3– Plants Weathering of rocks Geologic uplift of rocks Runoff Consumption Sedimentation Soil Leaching Decomposition

61. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ECOSYSTEM ALTERATION CONNECTION 37.20 Ecosystem alteration can upset chemical cycling The Hubbard Brook Experimental Forest is a long-term study of nutrient cycling – Natural conditions – Water loss balanced between runoff and transpiration/evaporation – Flow of nutrients in and out of watersheds nearly balanced

62. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – Logged and sprayed watershed Runoff increased 30 -40% Net loss of nutrients was huge Nitrate concentration in creek was 60 times greater – Other long-term findings Acid precipitation has resulted in calcium loss Forest plants are not adding new growth because of calcium deficiency

65. LE 37-20c Control Deforested Completion of tree cutting 80.0 60.0 40.0 20.0 4.0 3.0 2.0 1.0 Nitrate concentration in runoff (mg/L) 1965196619671968

66. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings TALKING ABOUT SCIENCE 37.21 David Schindler talks about the effects of nutrients on freshwater ecosystems Dr. David Schindler was involved in environmental research that resulted in the banning of phosphates in detergents Nutrient runoff from agricultural lands and large livestock operations may cause excessive algal growth This cultural eutrophication reduces species diversity and harms water quality

67. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A combination of factors threaten freshwater ecosystems – Acid precipitation – Climate warming – Changes in land use

69. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37-21b