2. Ecology Biology Chapter 3

3. Ecology  The scientific study of interactions among organisms and their environment

4. Biotic vs. Abiotic  Biotic Factors  Living organisms  Example: plants, animals, bacteria, etc.  Abiotic Factors  Non-living factors  Examples: Temperature, air currents, moisture, light, soil, etc.

5. Organism  Individual belonging to a species  All organisms depend on other organisms for survival

6. Species  Species—organisms with similar anatomical features that can interbreed and produce fertile offspring.

7. Population  A group of organisms of one species that live in the same geographic area

8. Community  A group of different populations that lives in the same geographic area

9. Ecosystem  A collection of all the organisms that live in a particular place, together with their nonliving environment

10. Biome  A group of ecosystems that have the same climate and dominant communities  Types:  Terrestrial  Aquatic

11. Biosphere  The combined portions of Earth in which all living things exist (land, water, air, atmosphere)

12. Summary of Levels of Organization Organism Population Community Ecosystem Biome

13. To sum it up…  Ecology is all about relationships!  How do organisms relate to each other within a population?  How do populations relate to each other within a community?  How do communities relate to each other within an ecosystem? How do they relate to their environment?  Remember, relationships can be beneficial or harmful!

14. Energy Sunlight is the main source of energy for life on Earth Less than 1 % of all the sun’s energy that reaches Earth’s surface is used by living things.

15. Other sources of energy  Some organisms make food from inorganic chemical compounds  Ex: Archaebacteria undergo chemosynthesis and obtain nutrients from mineral water from hot springs

16. Autotrophs  Autotrophs are also called producers  Organisms that capture energy from sunlight or chemicals to produce food.  This is done either by photosynthesis or chemosynthesis.  Ex: plants, algae, certain bacteria

17. Heterotrophs  Heterotrophs are also called consumers.  Organisms that rely on other organisms for their energy and food supply.  Ex: animals, fungi (decomposers), protists, certain bacteria

18. Types of heterotrophs  Herbivores—obtain energy from eating plants  Carnivores—obtain energy from eating animals  Omnivores—obtain energy from eating both plants and animals  Detrivores—obtain energy from feeding on animal and plant remains  Decomposers—break down organic matter ex: bacteria and fungi

19. Energy flow  Energy flows through an ecosystem in one direction, from the sun (or inorganic compounds) to producers, to consumers.

20. Food Chain  Energy stored by producers is passed through an ecosystem along a food chain.  Food chain—a series of steps in which organisms transfer energy by eating and being eaten.

21. Food Chain

22. Food Web  Feeding relationships are usually more complex than can be shown in a food chain.  Food web—when feeding relationships form a network of interactions.

23. Food Web

24. Trophic Levels  Trophic level—Each step in a food chain or food web  Producers make up the first trophic level. Consumers make up the second, third, or higher levels.  Consumers depend on the trophic level below it for energy

25. Ecological Pyramids  Ecological Pyramids—a diagram that shows the relative amounts of energy or matter contained in each trophic level of a food chain or food web.

26. Energy Pyramid Only about 10% of energy available within one trophic level is transferred to organisms at the next trophic level. The rest is spent for life processes (like respiration, movement, and reproduction), some of the remaining energy is lost as heat

27. Biomass Pyramid The total amount of living tissue within a trophic level is biomass.

28. Pyramid of Numbers Pyramids can also be based on the numbers of organisms at each trophic level.

29. Cycles of Matter  Unlike the one-way flow of energy, matter is recycled between ecosystems.  This recycling is accomplished by Biogeochemical Cycles.  Biogeochemical Cycles recycle the same molecules around again and again. You are made of molecules that are millions or billions of years old!

30. The Water Cycle  All life requires liquid water.  Water moves between the living things, the ocean, the atmosphere, and land.  Evaporation—when water changes from liquid form to gas  Transpiration—When water enters the atmosphere by evaporating from the leaves of plants.  Condensation—When water vapor turns into tiny liquid droplets.

31. Water Cycle Diagram

32. Nutrients  Nutrients—All of the chemical substances that an organism needs to sustain life.

33. The Carbon Cycle  Biological processes—photosynthesis, respiration, and decomposition take up and release Carbon and Oxygen.  Geochemical processes—volcanic activity and erosion release CO 2  Due to decomposition and pressure over time, Carbon is stored underground (fossil fuels)  Mining, burning forests and fossil fuels release CO2 back into the atmosphere

34. Carbon Cycle Diagram

35. The Nitrogen Cycle  All organisms require nitrogen to make amino acids, which make proteins.  Nitrogen gas makes up 78% of the Earth’s atmosphere.  Ammonia (NH3), nitrates, and nitrites are found in the wastes produced by organisms and is decaying organic matter.

36. The Nitrogen Cycle  Only certain types of bacteria can use nitrogen gas directly. These bacteria live in soil and on the roots of plants.  Nitrogen fixation— The process by which bacteria convert nitrogen gas into ammonia  Other bacteria convert the ammonia into nitrates and nitrites, which producers use to make proteins. Consumers get nitrogen from eating producers.

37. Nitrogen Cycle Diagram

38. The Phosphorous Cycle  Phosphorous is needed to help form DNA and RNA.  Phosphorous is released into the atmosphere when rocks and sediments wear down over time.  Plants absorb phosphates from soil or water, and consumers get phosphates from eating plants.

39. Phosphorous Cycle Diagram

40. Community Interactions  Interactions between organisms have a huge impact on ecosystems.

41. Community Interactions  Types of interactions:  Competition—when organisms attempt to use a resource in the same place at the same time.  Competitive exclusion principle—no two species occupy the same niche in the same habitat. Predation—an interaction where one organism captures and feeds on another organism Predation—an interaction where one organism captures and feeds on another organism

42. More interactions  Symbiosis—a relationship in which two species live closely together.  Usually one species lives on or inside of another.  One species always benefits and other can be harmed, helped, or have no effect.

43. Types of Symbiosis  Mutualism—a symbiotic relationship in which both species benefit. Ex: Flowers and the insects that pollinate them.  Commensalism—a symbiotic relationship in which one species benefits and the other is unaffected. Ex: barnacles on a whale  Parasitism—a symbiotic relationship where one species benefits and the other is harmed. Ex: Fleas, ticks, tapeworms and their hosts.

44. Types of Symbiosis. The acacia tree and Pseudomyrmex ants are an example of mutualism

45. Types of Symbiosis. An epiphyte plant is an example of commensalism

46. Types of Symbiosis. A tapeworm is an example of a parasite

47. Ecological Succession  Ecological Succession—The series of predictable changes that occurs in a community over time.  As an ecosystem changes, older species gradually die out and new species move in.

48. Types of Succession  Primary Succession—When succession occurs on surfaces where no soil exists. Ex: after a volcanic eruption builds a new island or covers land with lava rock.  Secondary Succession—When a disturbance changes an ecosystem without removing the soil. Ex: a forest after a fire.

49. Succession  Climax Community—an older, established community that is no longer changing (as much)

50. Populations  Population Density—The number of individuals per unit area  Ex: number of dandelions per m 2

51. Population Growth  Several factors affect population size:  Births— # of organisms born  Deaths— # of organisms that die  Immigration—The movement of organisms into a population  Emigration—The movement of organisms out of a population

52. Exponential Growth  Unrestricted populations of organisms experience exponential growth.  Must have unlimited resources

53. Exponential Growth Graph

54. Logistic growth  As resources become less available, population growth slows or stops (birth rate=death rate) This is called leveling off.  Carrying capacity—The maximum number of organisms that the environment can support

55. Logistic growth graph

56. Limiting factors  Limiting factor—a factor that causes population growth to decrease.

57. Density-Dependent factors  Density-Dependent factors— limiting factors whose effects increase as the size of the population increases  Ex: Competition, predation, parasitism, disease

58. Density-Independent factors  Density-Independent factors— Limiting factors that affect all populations in similar ways, regardless of population size and density  Ex: Natural disasters, seasonal cycles, certain human activities

59. Human populations  Demography—The scientific study of human populations

61. Exponential Growth in our human population  Since the industrial revolution of the 1800s the human population has been experiencing exponential growth.

62. Effects of increased growth  If the human population continues to grow at an exponential rate this could cause:  Starvation and death for millions  Some countries to set limits on birth rates

63. Slowing population growth  Human population growth can be slowed by:  Global epidemics (influenza, HIV, etc.)  Limiting birth rates

64. Biodiversity  Biodiversity—the total variety of organisms in the biosphere.  It is important to preserve biodiversity for a variety of reasons (food webs, new medicine, etc.)

65. Maintaining biodiversity  Humans can help maintain biodiversity by:  Enforcing the Endangered Species Act  Making laws protecting the wilderness (including rainforests)

66. Destroying Biodiversity  Humans can destroy biodiversity by:  Habitat destruction  Introducing invasive species  (ex: Zebra mussels in Great Lakes, rabbits in Australia, etc.)

67. The Greenhouse effect  The Greenhouse effect—  Water vapor and greenhouse gases (CO2, methane, etc.) trap heat from the sun in our atmosphere. This keeps Earth warmer, like the glass panels of a greenhouse.

68. Global Warming  Global Warming—An increase in greenhouse gases which increases the amount of heat trapped in Earth’s atmosphere.

69. Human activities causing global warming  Burning fossil fuels and cutting down the rainforests are increasing greenhouse gases (especially CO2), which is most likely causing global warming.

70. Air Pollution  The quality of our air is important to our health. Burning fossil fuels and factory emissions being released into the air contribute to air pollution.