Pre IB Biology Ecology


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Pre IB Biology Ecology

  1. 1. Ecology <ul><li>The branch of biology that deals with the interactions between organisms and the relationship between organisms and the environment. </li></ul>
  2. 2. Biosphere <ul><li>The portion of the earth in which life exists. </li></ul><ul><li>The biosphere is composed of many complex ecosystems that include water, soil, and air. </li></ul>
  3. 3. Ecosystem <ul><li>Includes all the members of the community plus the physical environment in which they live in. </li></ul>
  4. 4. Community <ul><li>Includes all the populations in a given area. </li></ul><ul><li>Ex : all plants, animals, and microorganisms make up a pond community </li></ul>
  5. 5. Population <ul><li>Includes all the members of a species found in a given area. </li></ul><ul><li>Ex: wolves in a field </li></ul>
  6. 6. Individual Species
  7. 8. Ecosystem <ul><li>Is the structural and functional unit studied in Ecology. </li></ul><ul><li>It is the interaction of a community with its physical environment. </li></ul><ul><li>Requirements for a Stable Ecosystem </li></ul><ul><ul><ul><li>Abiotic Factors </li></ul></ul></ul><ul><ul><ul><li>Biotic Factors </li></ul></ul></ul>
  8. 9. Requirements for a Stable Ecosystem <ul><li>The ecosystem involves interactions between </li></ul><ul><li>living and nonliving things. Certain requirements </li></ul><ul><li>must be met for a stable ecosystem to exist: </li></ul><ul><li>There must be a constant supply of energy (sunlight for photosynthesis). </li></ul><ul><li>There must be a recycling of materials between organisms and the environment. </li></ul><ul><li>Biodiversity must exist. This refers to the presence of a wide range of different species of organisms living and interacting with each other and with their nonliving environment. </li></ul>
  9. 10. Ecosystem Factors <ul><li>Energy Flow </li></ul><ul><li>Nutrient Cycles </li></ul><ul><li>Organism interaction </li></ul>
  10. 11. I. Energy Flow Relationships <ul><li>For an ecosystem to be self-sustaining, there must be a flow of energy between organisms. </li></ul><ul><li>The pathway of energy flow through the living components of an ecosystem are represented by food chains and food webs . </li></ul>
  11. 12. The ultimate energy source of the earth is the sun
  12. 13. Energy moves through three basic classes of organisms: <ul><li>Producers - include green plants and other photosynthetic organisms that synthesize the organic nutrients that supply energy to other members in the community. </li></ul><ul><li>Consumers - include all heterotrophic organisms. Organisms that feed on green plants are primary consumers , or herbivores. Secondary consumers , or carnivores, feed on other consumers. </li></ul><ul><li>Decomposers – are the organisms (saprophytes) that break down wastes and dead organisms so that chemical materials are returned to the environment for use by other living organisms. </li></ul>
  13. 14. Producers
  14. 15. Consumers
  15. 16. Decomposers
  16. 17. Food Chains <ul><li>Green plants and other photosynthetic organisms are the organisms in an ecosystem that can convert radiant energy from sunlight into food. </li></ul><ul><li>A food chain involves the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten. </li></ul>
  17. 18. Energy Pyramid <ul><li>The greatest amount of energy in a community is present in the organisms that make up the producer level. </li></ul><ul><li>Only a small portion of this energy is passed on to primary consumers, and only a smaller portion is passed on to secondary consumers (on average, only about 10% of the energy). </li></ul><ul><li>A pyramid of energy can be used to illustrate the loss of usable energy at each feeding level. </li></ul>
  18. 20. Energy Pyramid
  19. 21. Food Webs <ul><li>In a natural community, most organisms eat more than one species and may be eaten, in turn, by more than one species. </li></ul><ul><li>Thus, the various food chains in a community are interconnected forming a food web. </li></ul>
  20. 24. II. Nutrient Cycles
  21. 25. Cycle of Materials <ul><li>In a self-sustaining ecosystem, various materials are recycled between organisms and the abiotic environment. </li></ul><ul><li>The recycling process allows materials to be used over and over again. </li></ul><ul><li>Three examples are: </li></ul><ul><li>1. Carbon cycle </li></ul><ul><li>2. Water cycle </li></ul><ul><li>3. Nitrogen cycle </li></ul>
  22. 26. Carbon Cycle <ul><li>Carbon is recycled through the environment by many processes, one is respiration and photosynthesis. </li></ul>
  23. 27. Water Cycle <ul><li>Here water moves between the earth’s surface and the atmosphere. </li></ul><ul><li>Evaporation - liquid water on earth’s surface changes to gas by the process of evaporation and enters the atmosphere in the form of water vapor. </li></ul><ul><li>Condensation - water vapor is returned to liquid state and falls as precipitation . </li></ul><ul><li>Some water vapor is added to the atmosphere by aerobic respiration in plants and animals and by transpiration in plants. </li></ul>
  24. 29. Nitrogen Cycle <ul><li>Nitrogen is needed by all living things because it is part of the structure of amino acids and proteins. </li></ul><ul><li>In this cycle, nitrogenous wastes and the remains of dead organisms are converted by decomposers and soil bacteria into compounds that can be used by autotrophs. </li></ul>
  25. 31. III. Organism interaction
  26. 32. Biotic Factors <ul><li>Living factors </li></ul><ul><li>These factors directly or indirectly affect the environment. </li></ul><ul><li>Thus, the organisms, their presence, parts, interaction, and wastes all act as biotic factors. </li></ul><ul><li>These interactions include: </li></ul><ul><li>1. Nutritional relationships </li></ul><ul><li>2. Symbiotic relationships </li></ul>
  27. 33. 1. Nutritional Relationships <ul><li>Involves the transfer of nutrients from one organism to another within an ecosystem. </li></ul><ul><li>In terms of nutrition, organisms are either autotrophs or heterotrophs . </li></ul>
  28. 34. Autotrophs <ul><li>An autotroph , or producer , is an organism that produces complex organic compounds from simple inorganic molecules using energy from light (by photosynthesis) or inorganic chemical reactions (chemosynthesis). </li></ul>
  29. 35. Types of Heterotrophs <ul><li>A. Saprophytes- include heterotrophic plants, fungi, and bacteria which feed on dead organisms. </li></ul><ul><li>Ex : mushrooms are saprophytes that feed off dead plants. </li></ul><ul><li>B. Herbivores - animals that feed on plants. </li></ul><ul><li>Ex : deer </li></ul><ul><li>C. Carnivores - animals that consume other animals. Two types: </li></ul><ul><ul><ul><li>a) predator – which kills and consume their prey. </li></ul></ul></ul><ul><ul><ul><li>b) scavenger - which feed on the remains of animals they did not kill. </li></ul></ul></ul><ul><li>D. Omnivores - animals that consume both plants and animals (humans). </li></ul>
  30. 36.                                             
  31. 37. 2. Symbiotic Relationships <ul><li>Different organisms may live together in a close association. </li></ul><ul><li>This is known as symbiosis. </li></ul><ul><li>There are three types: </li></ul><ul><li>1. Commensalism 2. Mutualism 3. Parasitism </li></ul><ul><li>KEY : </li></ul><ul><li>+ = benefits </li></ul><ul><li>- = harmed </li></ul><ul><li>o = not affected </li></ul>
  32. 38. Commensalism <ul><li>(+ , o) </li></ul><ul><li>In this relationship, one organism benefits and the other is not affected. </li></ul><ul><li>Ex : barnacles on a whale </li></ul>
  33. 39. Commensalism
  34. 40. Mutualism <ul><li>(+ , +) </li></ul><ul><li>In this relationship both organisms benefit from each other. </li></ul><ul><li>Ex : protozoan living in the digestive tract of termites. </li></ul><ul><li>Wood eaten by termites is digested by the protozoan. The nutrients released supply both organisms. </li></ul><ul><li>Another example would be nitrogen-fixing bacteria in nodules on the roots of legumes. </li></ul>
  35. 41. Mutualism
  36. 42. Parasitism <ul><li>(+ , - ) </li></ul><ul><li>In this relationship, the parasite benefits at the expense of the host. </li></ul><ul><li>Ex : athlete’s foot fungus on humans </li></ul><ul><li>tapeworm and heartworm in dogs. </li></ul>
  37. 43. Parasitism
  38. 44. Niche <ul><li>Each species occupies a niche in the community. A niche is the role the species plays, and includes the type of food it eats, where it lives, where it reproduces, and its relationships with other species. </li></ul>
  39. 45. Limiting Factors <ul><li>Determines the types of organisms which may exist in that environment. </li></ul><ul><li>Examples are : </li></ul><ul><ul><ul><li>A low temperature common to northern latitudes determines in part what species of plants can exist in that area. </li></ul></ul></ul><ul><ul><ul><li>The amount of oxygen dissolved in a body of water will help determine which species of fish will exist there. </li></ul></ul></ul><ul><ul><ul><li>The amount of food in a given area. </li></ul></ul></ul>
  40. 46. Competition <ul><li>Different species living in the same environment, or habitat , may require the same resources. When the resources are limited, competition occurs among the species. </li></ul><ul><li>Competition - is the struggle between different species for the same limited resources. The more similar the needs of the species, the more intense the competition. </li></ul>
  41. 47. Ecosystem Formation <ul><li>Ecosystems tend to change over a long period of time until a stable ecosystem is formed. </li></ul><ul><li>Both the living and nonliving parts of an ecosystem change. </li></ul>
  42. 48. Ecological Succession <ul><li>The replacement of one kind of community with another is called ecological succession. </li></ul><ul><li>The kind of stable ecosystem that develops in a particular geographical area depends on climate. </li></ul><ul><ul><ul><li>Colonizers The first organism that can live on bare rock since it stores little water and has few available nutrients. Colonizers like moss start to erodethe rock and so form a thin soil </li></ul></ul></ul><ul><ul><ul><li>Pioneer organisms - are the first plants to populate an area. Lichens and algae may be pioneer organisms on bare rock. </li></ul></ul></ul><ul><ul><ul><li>Climax Communities - Succession ends with the development of a climax community in which the populations of plants and animals exist in balance with each other and the environment. </li></ul></ul></ul>
  43. 49. Colonizers Lichen
  44. 50. <ul><li>G rasses and ferns grow in the thin soil and their roots accelerate soil formation. </li></ul><ul><li>Pioneer species </li></ul>Ferns
  45. 51. Herbaceous Plants goosegrass
  46. 52. Larger plants ( Small trees and large shrubs) <ul><li>bramble, gorse, hawthorn, broom and rhododendron can now grow in the good soil. These grow faster and so out-compete the slower-growing pioneers. </li></ul>Hawthorn
  47. 53. Climax Community: Large Trees Beech Tree
  48. 55. Biomes <ul><li>The earth can be divided into broad geographic regions by climate. </li></ul><ul><li>The kind of climax ecosystem that develops in these regions are called biomes. </li></ul><ul><li>Biomes can be terrestrial or aquatic . </li></ul>
  49. 56. Aquatic Biomes <ul><li>Is a continuous body of water that covers more than 70% of the earth’s surface. </li></ul><ul><li>Supports a great variety of life forms. </li></ul><ul><li>Includes the area in which most of the photosynthesis on earth occurs. </li></ul><ul><li>Ex: Plankton - are organisms that float near the surface and are carried by ocean currents. Plankton include protists and algae. These organisms make up the lowest level of the marine food web </li></ul>
  50. 57. Terrestrial Biomes
  51. 58. Tundra
  52. 59. Tundra <ul><li>Permanently frozen subsoil. </li></ul><ul><li>Plants consist of lichens, mosses, and grasses. </li></ul><ul><li>Examples of animals consist of wolves, Caribou and snowy owls. </li></ul>
  53. 60. Taiga
  54. 61. Taiga <ul><li>Long severe winters. </li></ul><ul><li>Summers with thawing subsoil. </li></ul><ul><li>Major plants are conifers. </li></ul><ul><li>Animals consist of the moose, deer, elk, and black bear. </li></ul>
  55. 62. Temperate Deciduous
  56. 63. Temperate Deciduous <ul><li>Moderate precipitation. </li></ul><ul><li>Cold winters with warm summers. </li></ul><ul><li>Plants consist of deciduous trees (maple, oak, and beech). </li></ul><ul><li>Animals are gray foxes, bobcats, deer, and raccoons. </li></ul>
  57. 64. Grassland
  58. 65. Grassland <ul><li>Prairies, Pampas (S. America), Steppes (Europe and Asia) </li></ul><ul><li>Temperate & Tropical Climates </li></ul><ul><ul><li>Variable rainfall, temperature and strong winds </li></ul></ul><ul><li>Animals (grazing animals) </li></ul><ul><ul><li>Pronghorn Antelope, Prairie Dog, Bison </li></ul></ul><ul><li>Vegetation </li></ul><ul><ul><li>Grasses, Cereal Grain </li></ul></ul>
  59. 66. Tropical Forest
  60. 67. Tropical Forest <ul><li>Heavy rainfall, constant warmth. </li></ul><ul><li>Consist of many species of broad-leaf plants. </li></ul><ul><li>Some animals are snakes, monkeys, and squirrels. </li></ul>
  61. 68. Desert
  62. 69. Desert <ul><li>Sparse rainfall </li></ul><ul><li>Extreme daily temperature fluctuations. </li></ul><ul><li>Plants consist of drought-resistant shrubs and succulent plants. </li></ul><ul><li>Examples of animals are kangaroo rat, snakes, and lizards. </li></ul>
  63. 70. Ecology Part II: Human Ecology
  64. 71. Exponential Growth <ul><li>Bacteria placed in nutrient broth of optimal temperature </li></ul><ul><li>Exponential growth : </li></ul><ul><li>when population growth at any point is 2 N , N= # of generations </li></ul><ul><li>will occur under ideal conditions with unlimited resources </li></ul>
  65. 72. <ul><li>Exponential Growth CANNOT continue indefinitely due to limiting factors : </li></ul><ul><ul><li>Factors that stop or control population growth </li></ul></ul><ul><ul><li>Examples: Food, light, water, space, parasitism and disease, predators, energy resources, oxygen, accumulation of waste products, competition, disasters – fire, floods, drought, etc. </li></ul></ul>
  66. 73. Carrying Capacity and Logistic Growth <ul><li>Logistic Growth: </li></ul><ul><ul><li>Exponential at first  then levels off as it reaches carrying capacity </li></ul></ul><ul><ul><li>Growth rate = 0 </li></ul></ul><ul><ul><li>S-shaped graph </li></ul></ul><ul><li>Carrying Capacity: </li></ul><ul><ul><li>Maximum population that environment can support </li></ul></ul>
  67. 74. Population Growth of Humans
  68. 75. Factors affecting human population growth <ul><li>Agricultural revolution/food production </li></ul><ul><li>Increase in knowledge of diseases </li></ul><ul><li>Better health care and hygiene/sanitation </li></ul><ul><li>Advances in Medicine and technology </li></ul><ul><li>Resulting in a decrease in death rate, a longer life span, and an increased birth rate in some areas </li></ul><ul><li>NOTE : there has been a decrease in fertility rates in underdeveloped nations </li></ul>
  69. 76. Limiting Resources <ul><li>Renewable Resources </li></ul><ul><ul><li>Can be replaced </li></ul></ul><ul><ul><li>Food supply, solar energy, wind/air, water, soil, living things (trees), geothermal energy, nuclear energy </li></ul></ul><ul><li>Non-Renewable Resources </li></ul><ul><li>- cannot be replaced in one’s lifetime </li></ul><ul><li>- fossil fuels </li></ul>
  70. 77. Source: United Nations, World Population Prospects, The 1998 Revision ; and estimates by the Population Reference Bureau. <ul><li>Human population is estimated to rise over 9 billion by the year 2150. </li></ul><ul><li>Many think it will then level off or decline at this point. </li></ul><ul><li>If growth continues, may result in population crash due to overcrowding and competition for food. </li></ul><ul><li>May also result in famines, disease and wars. </li></ul>
  71. 78. Human Population Growth and the Environment As the human population grows, we take up more space, consumer more resources, and produce more wastes!
  72. 79. Disruption of Existing Ecosystems <ul><li>1. Urbanization </li></ul><ul><ul><li>Shift from rural (farming) areas to cities </li></ul></ul><ul><ul><li>Increased Industrialization </li></ul></ul><ul><ul><li>Destruction of farmland and deforestation </li></ul></ul><ul><ul><li>Results in </li></ul></ul><ul><ul><ul><li>Decreased amount of space for other species </li></ul></ul></ul><ul><ul><ul><li>Loss of habitats </li></ul></ul></ul><ul><ul><ul><li>Decreased biodiversity </li></ul></ul></ul><ul><ul><ul><li>Disruption of ecosystem by introducing new species into an area w/no known predator </li></ul></ul></ul>
  73. 80. 2. Poor Farming Practices <ul><li>Over farming and over grazing </li></ul><ul><ul><li>result in areas w/o a cover of vegetation </li></ul></ul><ul><ul><li>No plants…no roots to hold soil </li></ul></ul><ul><ul><li>Leads to soil erosion: removal of soil by wind or water and desertification </li></ul></ul><ul><ul><li>Deforestation – can also lead to soil erosion, washing away of nutrients </li></ul></ul>
  74. 81. 3. Pollution <ul><li>Noise </li></ul><ul><li>Water – ex. Sewage, animal wastes, toxic chemicals (DDT, fertilizers), thermal pollution </li></ul><ul><li>Air – ex. burning of fossil fuels leads to increased levels of carbon dioxide, acid rain, smog </li></ul><ul><li>Land – ex. solid wastes, garbage </li></ul>
  75. 82. 3a. Acid Rain <ul><li>Precipitation that has a low pH due to sulfur and nitrogen compound added to the air from the burning of fossil fuels </li></ul>
  76. 83. Acid Rain
  77. 84. 3b. Global Warming <ul><li>Earth’s average temp is increasing due to an increase in greenhouse gases like carbon dioxide </li></ul><ul><li>Greenhouse Effect </li></ul><ul><ul><li>Increased carbon dioxide traps heat </li></ul></ul>
  78. 85. 3c. Ozone Depletion <ul><li>Destruction of the ozone shield which is the layer of ozone gas in the upper atmosphere that protects the earth from the sun’s radiation </li></ul>
  79. 86. Causes of Ozone Depletion -the release of gases called chlorofluorocarbons (CFC’s) -CFC’s: used as coolants in fridges, air conditioners, aerosol cans, and in plastic production
  80. 87. Smog <ul><li>Gray or brown haze that contains many airborne pollutants from automobile pollutants or industrial processes </li></ul>
  81. 88. How have we destroyed the habitats of organisms? <ul><li>Habitat Destruction </li></ul><ul><ul><li>Loss of biodiversity </li></ul></ul><ul><li>Deforestation </li></ul><ul><li>Direct harvesting </li></ul><ul><li>Urbanization </li></ul><ul><li>Poaching </li></ul>
  82. 89. The Value of Biodiversity <ul><li>Species diversity – the # of different species in a biosphere </li></ul><ul><li>Genetic diversity – the sum total of all genetic differences </li></ul><ul><li>Provide us with foods, industrial products, medicines, etc. </li></ul>
  83. 90. Threats to Biodiversity <ul><li>Habitat alteration </li></ul><ul><li>Demand for wildlife products </li></ul><ul><li>Pollution – biological magnification (ex. bald eagle and DDT) </li></ul><ul><li>Introduced species – invasive species </li></ul>
  84. 91. Biomagnification <ul><li>Biomagnification , is the increase in concentration of a substance, such as the pesticide DDT, that occurs in a food chain as a consequence of: </li></ul>