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2 Populations


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2 Populations

  1. 1. Populations
  2. 2. Populations <ul><li>All individuals of a given species in a particular habitat </li></ul>
  3. 3. Communities <ul><li>All the organisms in a defined area </li></ul><ul><ul><ul><li>Ecosystem </li></ul></ul></ul><ul><ul><ul><ul><li>A community plus all the non-living (abiotic) components in a habitat </li></ul></ul></ul></ul>
  4. 4. Populations <ul><li>Measuring Populations </li></ul><ul><li>How populations are regulated </li></ul>
  5. 5. Measuring Populations <ul><li>Population Density </li></ul><ul><ul><li>Number of individuals per unit area </li></ul></ul>
  6. 6. Population Density <ul><li>Influenced by </li></ul><ul><ul><li>Mortality </li></ul></ul><ul><ul><li>Emigration </li></ul></ul><ul><ul><li>Natality </li></ul></ul><ul><ul><li>Immigration </li></ul></ul>
  7. 7. Population Growth <ul><li>Population density fluctuates </li></ul><ul><li>Natality + immigration = mortality + emigration </li></ul><ul><li>Mortality is usually high </li></ul>
  8. 8. Types of Populations <ul><li>Open </li></ul><ul><ul><li>Natality, mortality, immigration and emigration affect population size </li></ul></ul><ul><li>Closed </li></ul><ul><ul><li>Only natality and mortality affect population size </li></ul></ul>
  9. 9. Exponential Growth <ul><li>Under favourable conditions </li></ul><ul><li>No predators, parasites or competition </li></ul>
  10. 10. Sigmoid Growth <ul><li>Natural conditions </li></ul><ul><li>Curve flattens because of </li></ul><ul><ul><li>Competition </li></ul></ul><ul><ul><li>Predators </li></ul></ul><ul><ul><li>Parasites </li></ul></ul><ul><ul><li>Environmental resistance </li></ul></ul><ul><ul><li>Carrying capacity </li></ul></ul>
  11. 11. Closed Population Growth <ul><li>No immigration or emigration </li></ul><ul><li>Population slowly kills itself </li></ul><ul><ul><li>Lack of </li></ul></ul><ul><ul><ul><li>Food </li></ul></ul></ul><ul><ul><ul><li>Space </li></ul></ul></ul><ul><ul><ul><li>Oxygen </li></ul></ul></ul><ul><ul><ul><li>Water </li></ul></ul></ul><ul><ul><li>Poisons itself </li></ul></ul>
  12. 12. J Curve <ul><li>Closed population </li></ul><ul><li>Upper limit </li></ul><ul><ul><li>Seasonal conditions </li></ul></ul><ul><li>Never reaches carrying capacity </li></ul>
  13. 13. Survivorship <ul><li>The chance of remaining alive to pass on your genes to the next generation </li></ul><ul><li>Life expectancy </li></ul><ul><li>Life span </li></ul>
  14. 14. Survival of the species <ul><li>Most energy is put into survival of species </li></ul>
  15. 15. Age Group structure
  16. 16. Population Distribution <ul><li>Clumped </li></ul><ul><li>Random </li></ul><ul><li>Evenly spread out </li></ul>
  17. 17. Clumped Populations <ul><li>Increases competition for food and space </li></ul><ul><li>Reduces drying out </li></ul><ul><li>Greater defence </li></ul><ul><li>Easier to find mates </li></ul><ul><li>May also be due to substrate </li></ul>
  18. 18. Evenly Spread <ul><li>Animals </li></ul><ul><ul><li>By competition or aggression </li></ul></ul><ul><ul><li>Defended territories </li></ul></ul><ul><ul><li>Limits population density </li></ul></ul><ul><li>Plants </li></ul><ul><ul><li>Shading </li></ul></ul><ul><ul><li>Competition </li></ul></ul><ul><ul><li>Allelopathy </li></ul></ul>
  19. 19. Population Regulation <ul><li>Abiotic </li></ul><ul><ul><li>Tolerance </li></ul></ul><ul><ul><li>Acclimation </li></ul></ul><ul><ul><li>Geographical Barriers </li></ul></ul><ul><ul><li>Liebig’s Law of Minimum </li></ul></ul><ul><li>Biotic </li></ul><ul><ul><li>Predation, paracitism </li></ul></ul><ul><ul><li>Disease, toxic wastes </li></ul></ul><ul><ul><li>Competition, Humans </li></ul></ul>
  20. 20. Tolerance
  21. 21. Acclimation <ul><li>When tolerance limits for an organism change they acclimatise </li></ul><ul><ul><li>Slow process </li></ul></ul><ul><ul><li>Usually to seasons </li></ul></ul>
  22. 22. Liebig’s Law <ul><li>The functioning of an organism in limited or controlled by whatever essential environmental factor is in the least favourable amount </li></ul>
  23. 23. Geographical Barriers <ul><li>Mountain ranges </li></ul><ul><li>Seas and oceans </li></ul><ul><li>Rivers </li></ul>
  24. 24. Predation
  25. 25. Humans <ul><li>Over-hunting </li></ul><ul><ul><li>Extinction </li></ul></ul>
  26. 26. <ul><li>Destroy habitats </li></ul><ul><ul><li>Draining swamps </li></ul></ul><ul><ul><li>Clearing forests </li></ul></ul>
  27. 27. <ul><li>Over-use of pesticides </li></ul>
  28. 28. <ul><li>Toxic wastes </li></ul>