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HEE Chapter 5


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HEE Chapter 5

  1. 1. Interactions: Environments and Organisms Chapter 5
  2. 2. Ecological Concepts <ul><li>Ecology - Study of ways organisms interact with each other and with their non-living surroundings. </li></ul><ul><li>Environment - Everything that affects an organism during its lifetime. </li></ul><ul><ul><li>Biotic - Living components </li></ul></ul><ul><ul><li>Abiotic - Non-living components </li></ul></ul>
  3. 3. Levels of Organization in Ecology
  4. 4. Ecological Concepts <ul><li>Limiting Factors - Any factor whose shortage or absence restricts species success. </li></ul><ul><ul><li>Range of Tolerance - Range of conditions an organism can survive in. </li></ul></ul><ul><ul><ul><li>Temperature </li></ul></ul></ul><ul><ul><ul><li>pH </li></ul></ul></ul><ul><ul><ul><li>DO </li></ul></ul></ul>
  5. 5. Habitat and Niche <ul><li>Habitat - Space an organism inhabits; defined by biological requirements of each particular organism. </li></ul><ul><ul><li>Usually highlighted by prominent physical or biological features. </li></ul></ul><ul><li>Niche - Functional role an organism has in its surroundings. </li></ul><ul><ul><li>Includes all ways an organism affects organisms with which it interacts as well as how it modifies its physical surroundings. </li></ul></ul><ul><li>Fig. 5.3 </li></ul>
  6. 6. Ecological Niche
  7. 7. Genes Population and Species <ul><li>Genes - Distinct pieces of DNA that determine the characteristics an organism displays. </li></ul><ul><li>Population - All organisms of the same kind found within a specific geographic region. </li></ul><ul><ul><li>Contains more kinds of genes than any single individual within the population. </li></ul></ul>
  8. 8. Genes Population and Species <ul><li>Species - Population of all organisms potentially capable of reproducing naturally among themselves(Interbreed), and producing viable offspring. </li></ul><ul><ul><li>Working definition that only applies to organisms that sexually reproduce. </li></ul></ul><ul><ul><ul><li>Some species are easy to recognize, while others are more difficult. </li></ul></ul></ul>
  9. 9. <ul><li>Natural Selection - Process that determines which individuals within a species will reproduce and pass their genes to the next generation. </li></ul><ul><li>Conditions: </li></ul><ul><ul><li>Individuals within a species show genetically determined variation. </li></ul></ul><ul><ul><li>Organisms within a species typically produce huge numbers of offspring, most of which die. </li></ul></ul>Natural Selection
  10. 10. Natural Selection Conditions <ul><ul><li>Excess number of individuals results in a shortage of specific resources. </li></ul></ul><ul><ul><li>Due to individual variation, some individuals have a greater chance of obtaining needed resources and thus have a greater likelihood of survival and reproduction. </li></ul></ul><ul><ul><li>As time passes, percentage of individuals showing favorable variations will increase while percentage showing unfavorable variations will decrease. </li></ul></ul>
  11. 11. Evolutionary Patterns <ul><li>Evolution - A change in the kinds of organisms that exist and in their characteristics. </li></ul><ul><ul><li>Ex. Building tolerance to pesticides. </li></ul></ul><ul><li>Speciation - Production of new species from previously existing species. </li></ul><ul><ul><li>Thought to occur as a result of a species dividing into two reproductively isolated subpopulations. </li></ul></ul>
  12. 12. Evolutionary Patterns <ul><li>Extinction - Loss of entire species. </li></ul><ul><ul><li>Of estimated 500 million species believed to have ever existed on earth, 98-99% have gone extinct. </li></ul></ul><ul><li>Co-Evolution - Two or more species can reciprocally influence the evolutionary direction of the other. </li></ul><ul><ul><li>Grazing animals and grass species. </li></ul></ul>
  13. 13. Kinds of Organism Interactions <ul><li>Predation - One animal kills/eats another. </li></ul><ul><ul><li>Predator benefits from food. </li></ul></ul><ul><ul><ul><li>Prey adaptation is manifested in a higher reproduction rate. </li></ul></ul></ul><ul><ul><ul><li>Fig. 5.7 </li></ul></ul></ul>
  14. 14. Kinds of Organism Interactions <ul><ul><li>Prey species benefits by eliminating non-adaptive genes from the gene pool. </li></ul></ul><ul><ul><ul><li>Poorly adapted predators are less likely to obtain food and thus pass on non-adaptive genes. </li></ul></ul></ul>
  15. 15. Competition <ul><li>Competition - Two organisms strive to obtain the same limited resource, and both are harmed to some extinct. </li></ul><ul><ul><li>Intraspecific - Members of same species competing for resources. (Mice for Cheese) </li></ul></ul><ul><ul><li>Interspecific - Members of different species competing for resources. (Fox & Hawk for Mice) </li></ul></ul><ul><li>The more similar the competing species, the more intense the competition. </li></ul><ul><li>Fig. 5.8 </li></ul>
  16. 16. Competition <ul><li>Competitive Exclusion Principle - No two species can occupy the same ecological niche in the same place at the same time. </li></ul><ul><ul><li>Less fit species must evolve into a slightly different niche. </li></ul></ul>
  17. 17. Symbiotic Relationships <ul><li>Symbiosis - Close, physical relationship between two different species. At least one species derives benefit from the interaction. </li></ul><ul><ul><li>Parasitism - One organism ( parasite ) lives in or on another organism ( host ), from which it derives nourishment. </li></ul></ul><ul><ul><ul><li>Ectoparasites - Live on host’s surface. </li></ul></ul></ul><ul><ul><ul><ul><li>Fleas </li></ul></ul></ul></ul><ul><ul><ul><li>Endoparasites - Live inside host. </li></ul></ul></ul><ul><ul><ul><ul><li>Tapeworms </li></ul></ul></ul></ul>
  18. 18. Symbiotic Relationships <ul><li>Commensalism - One organism benefits while the other is not affected. </li></ul><ul><ul><li>Remoras and Sharks </li></ul></ul><ul><li>Mutualism - Both species benefit. Obligatory in many cases as neither can exist without the other. </li></ul><ul><ul><li>Mycorrhizae </li></ul></ul>
  19. 19. Community and Ecosystem Interactions <ul><li>Community - Assemblage of all interacting species of organisms in an area. </li></ul><ul><li>Ecosystem - Defined space in which interactions take place between a community, with all its complex interrelationships, and the physical environment. </li></ul>
  20. 20. Major Roles of Organisms in Ecosystems <ul><li>Producers - Organisms able to use sources of energy to make complex organic molecules from simple inorganic molecules in the environment. </li></ul><ul><ul><li>Ex. Grasses, Trees, Moss, Ferns </li></ul></ul>
  21. 21. Roles of Organisms <ul><li>Consumers - Consume organic matter to provide themselves with energy and organic matter necessary for growth and survival. </li></ul><ul><ul><li>Primary Consumers </li></ul></ul><ul><ul><ul><li>Herbivores (plants) </li></ul></ul></ul><ul><ul><li>Secondary Consumers </li></ul></ul><ul><ul><ul><li>Carnivores (animals) </li></ul></ul></ul><ul><ul><ul><li>Omnivores (plants and animals) </li></ul></ul></ul><ul><ul><li>Scavengers (dead animals) </li></ul></ul>
  22. 22. Roles of Organisms <ul><li>Decomposers </li></ul><ul><ul><li>Digest organic molecules in detritus into simpler organic compounds, and absorb soluble nutrients. (Bacteria and Fungi) </li></ul></ul><ul><ul><ul><li>Use non-living organic matter as source of energy. </li></ul></ul></ul><ul><li>Keystone Species </li></ul><ul><ul><li>Play critical role in maintenance of specific ecosystems. </li></ul></ul><ul><ul><ul><li>Bison in American Tall Grass Prairie </li></ul></ul></ul>
  23. 23. Energy Flow Through Ecosystems <ul><li>Each step in the flow of energy through an ecosystem is known as a trophic level . </li></ul><ul><ul><li>As energy moves from one trophic level to the next, most of the useful energy (90%) is lost as heat (2 nd Law of Thermodynamics). </li></ul></ul><ul><ul><ul><li>Because energy is difficult to track, biomass (weight of living material) is often used as a proxy. </li></ul></ul></ul>
  24. 24. Energy Flow Through an Ecosystem
  25. 25. Food Chains and Food Webs <ul><li>Food Chain - Passage of energy from one trophic level to the next due to one organism consuming another. </li></ul><ul><ul><li>Some chains rely on detritus. </li></ul></ul><ul><li>Food Web - Series of multiple, overlapping food chains. </li></ul><ul><ul><li>A single predator can have multiple prey species at the same time. </li></ul></ul><ul><ul><li>Fig. 5.15 </li></ul></ul>
  26. 26. Food Chain
  27. 27. Nutrient Cycles in Ecosystems <ul><li>Organisms are composed of molecules and atoms that are cycled between living and non-living portions of an ecosystem. </li></ul><ul><ul><li>Biogeochemical Cycles - another name for nutrient cycles. </li></ul></ul>
  28. 28. Carbon Cycle <ul><li>Carbon and oxygen combine to form carbon dioxide. </li></ul><ul><ul><li>Plants use carbon dioxide during photosynthesis to produce sugars. </li></ul></ul><ul><ul><ul><li>Plants use sugars for plant growth. </li></ul></ul></ul><ul><ul><ul><ul><li>Herbivores eat plants, and incorporate molecules into their structure. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Respiration breaks down sugars releasing CO 2 and water back into the atmosphere. </li></ul></ul></ul></ul></ul>
  29. 29. Carbon Cycle
  30. 30. Nitrogen Cycle <ul><li>Cycling of nitrogen atoms between abiotic and biotic ecosystem components. </li></ul><ul><ul><li>Producers unable to use atmospheric N. </li></ul></ul><ul><ul><ul><li>Must get nitrate NO 3 or ammonia NH 3. </li></ul></ul></ul><ul><ul><li>Nitrogen-fixing bacteria converts nitrogen gas N 2 into ammonia. Legumes (Roots) </li></ul></ul><ul><ul><ul><li>Plants construct organic molecules. </li></ul></ul></ul><ul><ul><ul><ul><li>Eaten by animals. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Drains soil of Nitrogen. </li></ul></ul></ul></ul><ul><ul><li>Decomposers also break down nitrogen-containing molecules releasing ammonia. </li></ul></ul>
  31. 31. Nitrogen Cycle <ul><li>Nitrifying bacteria are able to convert ammonia to nitrite, which can be converted to nitrate. </li></ul><ul><li>Denitrifying bacteria are able to (under anaerobic conditions) covert nitrite to nitrogen gas (N 2 ) which is ultimately released into the atmosphere. </li></ul>
  32. 32. Nitrogen Cycle
  33. 33. Phosphorus Cycle <ul><li>Phosphorus is not present in the atmosphere as a gas. </li></ul><ul><ul><li>Phosphorus compounds released by erosion and become dissolved in water. </li></ul></ul><ul><ul><ul><li>Plants use phosphorus to construct necessary molecules. </li></ul></ul></ul><ul><ul><ul><ul><li>Animals gain necessary P via herbivory. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Decomposers recycle into soil. </li></ul></ul></ul></ul></ul>
  34. 34. Phosphorus Cycle
  35. 35. Human Impact on Nutrient Cycles <ul><li>Two activities caused significant changes in carbon cycle: </li></ul><ul><ul><li>Burning of fossil fuels. (2001 – IPCC Report) </li></ul></ul><ul><ul><li>Converting forests to agricultural land. </li></ul></ul><ul><li>Fossil fuel burning also increased amount of nitrogen available to plants. </li></ul><ul><li>Fertilizer carried into aquatic ecosystems. </li></ul><ul><ul><ul><li>Increase aquatic plant growth rate. </li></ul></ul></ul><ul><ul><ul><ul><li>Lowered oxygen concentrations. </li></ul></ul></ul></ul>
  36. 36. Review <ul><li>Ecological Concepts </li></ul><ul><ul><li>Habitat and Niche </li></ul></ul><ul><li>Natural Selection and Evolution </li></ul><ul><li>Organism Interactions </li></ul><ul><ul><li>Predation </li></ul></ul><ul><ul><li>Competition </li></ul></ul><ul><li>Community and Ecosystem Interactions </li></ul><ul><ul><li>Roles of Organisms </li></ul></ul><ul><ul><li>Energy Flow Through Ecosystems </li></ul></ul><ul><ul><li>Nutrient Cycles in Ecosystems </li></ul></ul>