Population Ecology, Succession

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Population Ecology, Succession

  1. 1. Population Ecology How do populations change over time?
  2. 2. Properties of populations <ul><li>pop. Size – is the # of individuals in the pop. </li></ul><ul><li>Pop. Density – how crowded a pop. is. </li></ul><ul><li>Dispersion – the distribution of the members of a pop. </li></ul><ul><ul><ul><li>Can be clumped </li></ul></ul></ul><ul><ul><ul><li>Evenly distributed </li></ul></ul></ul><ul><ul><ul><li>Randomly distributed </li></ul></ul></ul>
  3. 3. Population dynamics & growth <ul><li>Populations change over time: </li></ul><ul><li>1) increase or decrease in size </li></ul><ul><li>2) age & mortality </li></ul><ul><li>Demography – the study of human population dynamics. </li></ul>
  4. 5. Measuring pop. Growth rates <ul><li>Exponential growth model – rapidly increasing or doubling in size. </li></ul><ul><li>Shown with a J- shaped curve </li></ul><ul><li>EX: mosquitoes, bacteria, some rodents, etc… </li></ul>
  5. 6. Exponential Growth
  6. 7. <ul><li>2) Logistical model – growth increase then stabilizes when the carrying capacity is reached. </li></ul><ul><li>Shown with an S-Shaped curve </li></ul><ul><li>EX: most larger organisms, lions, elephants, etc… </li></ul>
  7. 8. Logistical Model – carrying capacity
  8. 9. What limits a population? <ul><li>RESOURCES!!!!! </li></ul><ul><li>Any single resource that limits a population is called the limiting resource! </li></ul>
  9. 10. Some factors that control population… <ul><li>1) Density Dependant Factors – any factor that limits a population because of the size of the population. </li></ul><ul><li>EX: Food, space, water, disease, etc.. </li></ul>
  10. 11. <ul><li>2) Density – Independent Factors – a factor that can affect a population of any size. </li></ul><ul><li>EX: natural disasters, weather, etc… </li></ul>
  11. 12. SUCCESSION How do habitats change over time?
  12. 13. Primary Succession <ul><li>Succession is the gradual, sequential changing of an area. </li></ul><ul><li>The habitat changes until the “climax community” is formed. </li></ul>
  13. 14. Primary succession <ul><li>Occurs in areas that have no soil </li></ul><ul><li>No plants or animals in the area </li></ul><ul><li>1 st inhabitant is called a “pioneer species” – it usually lichen. </li></ul><ul><li>Soil is slowly formed and new plants/ animals gradually move into the area </li></ul><ul><li>Can occur because of a volcano or a new island forms or an icecap recedes </li></ul>
  14. 15. Primary Succession
  15. 16. Secondary succession <ul><li>Occurs in an area that has soil </li></ul><ul><li>Is usually the result of some disruption to a previous community. (fire, flood, etc…) </li></ul><ul><li>Happens quicker than primary succession. </li></ul>
  16. 17. Secondary Succession

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