This document provides a summary of key concepts relating to communities, ecosystems, and their structure and function. It discusses topics like biotic interactions between species, characteristics of communities, trophic structure and energy flow through ecosystems, and human impacts and disturbances to communities and nutrient cycles. Specific examples are given to illustrate concepts like symbiotic relationships, keystone species, mimicry, and how altered ecosystems can disrupt nutrient cycling.

1. Chapter 37:Communities & Ecosystems Communities and Ecosystems

2. Ecology….. Ecosystem STRUCTURE and FUNCTION depend on the interactions of the community with its abiotic environment Community STRUCTURE and FUNCTION depend on the interactions among organisms…(biotic)

3. Biotic Interactions…parasitic fungi A dead carpenter ant attached to leaf in the understory of a Thai forest. Before killing the ant, the fungus growing from ant's head changed the ant's behavior, causing it to bite into the leaf vein. (Credit: David Hughes) Attack of the zombie ant! Though it may seem like the perfect title for a cheesy horror movie, scientists have discovered more about a parasitic fungus that essentially takes over the brain and body of tropical carpenter ants -- ultimately causing its host to die at a spot where the fungus has the best chance of reproducing.

5. INVASION!! Does this “invader” disrupt community structure?

7. STRUCTURAL FEATURES OF COMMUNITIES What is a community? What are some of the key characteristics of a community? Species diversity Species richness Relative abundance Dominant species Response to disturbances Trophic structure: feeding relationships among species

8. Figure 1.1. Species richness and abundance of termites collected from transects in seven land-use types in Jambi Province, Central Sumatra http://www.asb.cgiar.org/data/dataset/8.htm Link to data: Species richness is the number of different species in a given area S = species richness n = total number of species present in sample population k = number of "unique" species (of which only one organism was found in sample population : Species abundance is the study of how common a particular species is in a given community.

9. Temperate Biome, Wetland Ecosystem

10. Competition: Why does it happen? Interspecific competition??? …examples… Intraspecific competition??? …examples…

11. Competitive exclusion principle Niche Results of Interspecific Competition? Or….maybe… Resource partitioning may evolve

12. What is happening here? ….why? LE 37-2a

13. LE 37-2b

14. Predation leads to diverse adaptations in both predator and prey Predation Adaptations….how do these evolve? Examples??? Camouflage Chemical defense

16. Biston betularia

17. Metalmark Moths…Watch Out! Batesian mimicry Palatable species mimics an unpalatable model http://images.google.com/imgres?imgurl=http://neurophilosophy.files.wordpress.com/2006/12/31.JPG&imgrefurl=http://neurophilosophy.wordpress.com/2006/12/22/the-moth-in-spiders-clothing/&usg=__KTsi4Eu0ERzQHpVhuHSLUm7Ozh0=&h=242&w=646&sz=29&hl=en&start=6&tbnid=fSCkjMPr45n43M:&tbnh=51&tbnw=137&prev=/images%3Fq%3Dmoth%2Bmimicry%2Bspider%26gbv%3D2%26hl%3Den

18. Mullerian mimicry Two unpalatable species mimic each other

21. Predation….diversity…. 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. Vores….. Herbivores and the plants they eat have various adaptations Herbivores are animals that eat plants or algae Plants have evolved defenses against herbivores Some herbivore-plant interactions illustrate coevolution Reciprocal evolutionary adaptations Change in one species acts as a new selective force on another species

25. Coevolution…

26. Symbiotic relationships Parasitism

27. Commensalism

28. Mutualism The obligate pollinating seed-consuming mutualism between senita cacti and senita moths is a mutualism that entails both benefits and costs to both the plant and pollinator. Senita cacti benefit from pollination, but incur costs due to larval fruit consumption. Senita moths benefit from fruit food resources, but incur costs to larval survival from fruit abortions.

29. Hawaian Bobtail Squid Euprymna scolopes, Vibrio fischeri & Counterillumination FIG. 1. Path of V. fischeri to the entrance of the host light organ. (A) Under conditions of anesthesia, the light organ can be seen as a dark mass (black arrow) through the ventral surface of the body wall. During each ventilatory cycle, the body cavity is expanded, water is drawn into the cavity (lateral green arrows) and then the body wall contracts, expelling water out (central green arrow) through the funnel (yellow). Because the light organ is circumscribed by the funnel, the water that is exiting passes over the light organ surface. Bar, 200 µm. (B) A scanning electron micrograph of one half of the ventral surface of a hatching light organ reveals the transparent, complex ciliated fields (cf) on the lateral surfaces of the organ. Water flows across these surfaces as shown by the broken green line and arrow. Bar, 50 µm. (C) A confocal micrograph of the ciliated surface of a living animal demonstrates that the appendages of the field are dynamic, most often forming a ring-like structure lateral to the main body of the light organ. Staining of the light organ with a fluorochrome that delineates the cells reveals the three pores at the base of the appendage, which are labeled 1, 2, and 3 to the left of each pore, designating the locations of the pore leading to the largest, mid-sized, and smallest crypts, respectively. Bar, 50 µm .

30. Disturbia…. Disturbance is a prominent feature of most communities Events such as fire, storms, floods Damage communities Remove organisms from communities Alter the availability of resources Can have positive effects

31. Ecological Sucession Primary succession: gradual colonization of barren rocks

34. Trophic Structure 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

35. … more trophic structure terms… 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

36. 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 The fiddler crab, an important detritovore in the salt marsh community.

38. The cyclic flow of nutrients within an ecosystem. The arrows show the paths of nutrient flow between the living and non- living players.

39. The sun's energy is converted by green plants to food energy. Red arrows: Light energy absorbed and utilized byplants. This includes blue and small amounts of green (1), red and small quantities of near infrared (2), and some far red (3) wavelengths. Green outline and arrow: net potential food energy produced through photosynthesis. Blue arrows: Energy reflected as light or heat into space.

40. The path of energy flow through a prairie ecosystem. Red arrow : sunlight energy coming in; Green arrows : food energy being passed from plants to animals Blue arrows : heat energy being dispersed to space.

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

42. 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

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

44. ECOSYSTEM STRUCTURE AND DYNAMICS 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

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

46. 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 http://www.youtube.com/watch?v=Y3RdwvEToJw

47. 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 0 500 1,000 1,500 2,000 2,500 Average net primary productivity (g/m 2 /yr)

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. 10% Rule… Laws of T-Dynamics 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, (Energy), 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

50. CONNECTION A production pyramid, (AKA Pyramid of Energy ), 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

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

52. Ecological Pyramids http://ngm.nationalgeographic.com/2008/07/kingman-reef/warne-text http://en.wikipedia.org/wiki/Kingman_Reef

53. BGC’s Chemicals are recycled between organic matter and abiotic reservoirs Biogeochemical cycles Cycle nutrients through both biotic and abiotic components Can be local or global

54. Consumers Producers Nutrients available to producers Detritivores Abiotic reservoir General BGC….

55. Hydrologic Cycle…by another name?? 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

56. 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

57. Carbon Cycle 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

58. 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

59. Nitrogen Cycle 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

60. The complex nitrogen cycle is a marvelous example of how microbes are important to life itself (parts of cycle illustrated by red or green arrows); this cycle also includes abiotic processes (blue arrows).

61. Some representatives of the many groups of microorganisms, primarily bacteria, that are involved in the five steps of the nitrogen cycle.

62. 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  )

63. Phosphorous Cycle 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

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

65. Phosphorus moves through ecosystems from rock and guano deposits to the sea and back to land again. Along the way, phosphorus is cycled between the living and nonliving Players.

66. ECOSYSTEM ALTERATION CONNECTION 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

67. 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

70. 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) 1965 1966 1967 1968

71. TALKING ABOUT SCIENCE 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

72. Freshwater Ecosystems Under Siege? A combination of factors threaten freshwater ecosystems Acid precipitation Climate warming Changes in land use Cultural Eutrophication

73. Figure 37-21b 0