Biotic and Abiotic Factors


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Biotic and Abiotic Factors

  1. 1. Biotic and Abiotic Influences on ecosystems
  2. 2. Limiting Factors <ul><li>What determines the size of a population and where a particular species can live? </li></ul>
  3. 3. <ul><li>Ideal biotic and abiotic conditions allow species to flourish. </li></ul>
  4. 4. <ul><li>Other conditions may lead to a species’ decline or even extinction . </li></ul>
  5. 5. <ul><li>A limiting factor is any factor that places an upper limit on the size of a population . </li></ul><ul><li>Limiting factors may be biotic , such as the availability of food, or abiotic , such as access to water. </li></ul>Limiting Factors
  6. 6. <ul><li>Human influences often act as limiting factors . </li></ul>
  7. 7. <ul><li>Abiotic factors, such as temperature , light and soil , can influence a species’ ability to survive. </li></ul>Limiting Factors
  8. 8. <ul><li>Every species is able to survive within a range of each of these factors. This range is called the species’ tolerance range . </li></ul>Abiotic Factors Near the upper and lower limits of the tolerance range, individuals experience stress . This stress will reduce their health and rate of growth and reproduction .
  9. 9. Abiotic Factors
  10. 10. <ul><li>Within a species’ tolerance range is an optimal range in which the species is best adapted . </li></ul><ul><li>The largest and healthiest populations of a species will occur when conditions are within the optimal range . </li></ul>Abiotic Factors
  11. 11. <ul><li>Some species have wide tolerance ranges, while others have much narrower ranges. </li></ul>Abiotic Factors Each species has a tolerance range for every abiotic factor .
  12. 12. <ul><li>Species with broad tolerance ranges will tend to be widely distributed and may easily invade other ecosystems. </li></ul>
  13. 13. <ul><li>The distribution of most terrestrial plant species is largely limited by a combination of temperature , precipitation and light . </li></ul>Abiotic Factors
  14. 14. <ul><li>The key abiotic factors in aquatic ecosystems are salt concentration as well as the availability of sunlight , oxygen and nutrients </li></ul>
  15. 15. <ul><li>While abiotic factors determine where a particular species is able to live , biotic factors often determine the species’ success . </li></ul>Biotic Factors
  16. 16. <ul><li>Many key biotic factors involve interactions between individuals . </li></ul>
  17. 17. <ul><li>Individuals are often in competition with members of their own species and with other species . </li></ul><ul><li>They compete for limited resources , such as food, light, space and mates </li></ul>
  18. 18. <ul><li>However, interactions between individuals are not limited to competition … </li></ul>
  19. 19. <ul><li>Predation occurs when an individual (the predator) kills and eats another individual (the prey ). </li></ul>
  20. 20. <ul><li>Mutualism occurs when two organisms interact, with both benefiting . </li></ul><ul><li>eg. lichen are formed by a mutualistic relationship between algae and fungi </li></ul>Biotic Factors
  21. 22. <ul><li>Commensalism occurs when one organism benefits and the other neither benefits nor is harmed . </li></ul>
  22. 23. <ul><li>As a population’s size increases, the demand for resources such as food, water, shelter and space also increases. </li></ul>Carrying Capacity
  23. 24. <ul><li>Eventually, there will not be enough resources for each individual . </li></ul><ul><li>Furthermore, as individuals become more crowded , they become more susceptible to predators and diseases . </li></ul>Carrying Capacity
  24. 25. <ul><li>Eventually, this will result in the population reaching the upper sustainable limit that the ecosystem can support - called the carrying capacity . </li></ul>Carrying Capacity
  25. 26. <ul><li>Carrying capacity = the maximum population size of a particular species that a given ecosystem can sustain </li></ul>Carrying Capacity
  26. 27. <ul><li>The carrying capacity can be altered through natural or human activity when resources are removed from or added to the ecosystem. </li></ul><ul><li>eg. the loss or introduction of a species can change the carrying capacity of the ecosystem for the other species </li></ul>Carrying Capacity