2.factors affecting variety of species in an ecosystem


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2.factors affecting variety of species in an ecosystem

  1. 1. Environmental Biology & GeneticsFactors Affecting the Variety of Species in an Ecosystem. n so vid Da M rG
  2. 2. BiodiversityEach species in a habitat or ecosystem has its own role to play and this role is called its niche, e.g. an owl would occupy the niche of “small mammal-eating bird of prey”.Monday, April 30, 2012 Mr G Davidson 2
  3. 3. BiodiversityOrganisms from different niches have special features which allow them to be successful and these features are called adaptations, e.g. behaviour, body structure, etc..Monday, April 30, 2012 Mr G Davidson 3
  4. 4. Darwin’s FinchesCharles Darwin investigated the finchpopulation of the Galapagos Islands in the1830s. On each island there is a different food source. He found that the beaks of the finches there had adapted to suit the diet of the birds.Monday, April 30, 2012 Mr G Davidson 4
  5. 5. Desert PlantsTo survive in deserts plants have to adapt to reduce water loss.  Roots go deep in the soil to find water.  Leaves are reduced to spines to reduce evaporation.  Surfaces are covered with a thick waxy cuticle.Monday, April 30, 2012 Mr G Davidson 5
  6. 6. BiodiversityBiodiversity is the range of species which exists within an ecosystem.A stable ecosystem: Contains a wide variety of species. Can exist for a very long time. Is not affected by small changes.Monday, April 30, 2012 Mr G Davidson 6
  7. 7. Biodiversity Biodiversity is very important to humans in a number of different ways: Importance ExampleFood Fish, wheat, etcMedicines Morphine from opium poppyRaw Materials Wood, cotton, etc..Recreation Hill walking, diving, etc..Genetic material Disease-resistant crops Monday, April 30, 2012 Mr G Davidson 7
  8. 8. Habitat DestructionHuman activities such as agriculture, construction and industry have lead to huge areas of natural habitat being cleared.This clearing has lead to the destruction of habitats and has drastically reduced the biodiversity of these areas.Monday, April 30, 2012 Mr G Davidson 8
  9. 9. Habitat DestructionDeforestation occurs in many parts of the world today, e.g. the Brazilian rainforests.This results in: Erosion of the land and loss of fertility in the soil. Reduction in biodiversity. Changes in climate.Monday, April 30, 2012 Mr G Davidson 9
  10. 10. Habitat DestructionPollution results in such things as acid rain being produced from sulphur dioxide killing fish and trees. untreated sewage being released into rivers which causes the number of invertebrate species to decrease.Monday, April 30, 2012 Mr G Davidson 10
  11. 11. Habitat DestructionThese have lead to a “Biodiversity Crisis” which is resulting in some species becoming extinct, e.g. Dodo Black rhinoceros Giant panda Blue whale Snow leopardMonday, April 30, 2012 Mr G Davidson 11
  12. 12. Habitat DestructionGrazing can also have a major effect on biodiversity, e.g. Over-grazing can lead to plant species being destroyed. Under-grazing can lead to a small number of very vigorous plant species becoming dominant.Monday, April 30, 2012 Mr G Davidson 12
  13. 13. Behavioural AdaptationsAll animals show behavioural adaptations.These are responses to changes in the environment called environmental stimuli.Such responses are called behavioural responses.Monday, April 30, 2012 Mr G Davidson 13
  14. 14. Behavioural AdaptationsExamples of behavioural responses include: Sea anemones are responsive to touch. Blowfly larvae are responsive to light. Swallows are responsive to daylength. Earthworms are responsive to vibrations.Monday, April 30, 2012 Mr G Davidson 14
  15. 15. Behavioural AdaptationsThese behavioural responses are important to the survival of the organism, e.g. Woodlice move towards conditions which are damp and dark and this is of “survival value” because: The damp conditions prevent the organisms from drying out. The darkness protects them from predators.Monday, April 30, 2012 Mr G Davidson 15
  16. 16. ResourcesEvery species needs certain resources (essential materials) from the environment to survive. E.g we need food, water, warmth and shelter.When any resource is in short supply there will be competition for it.Monday, April 30, 2012 Mr G Davidson 16
  17. 17. CompetitionCompetition occurs when a number of organisms require the same resource.Competition between members of the same species is very intense because they are competing for the same resource.Monday, April 30, 2012 Mr G Davidson 17
  18. 18. CompetitionCompetition between members of different species is less intense because they are not always competing for the same resource.In such cases a compromise is often reached to reduce the competition.Monday, April 30, 2012 Mr G Davidson 18
  19. 19. Competition Plants compete for such things as:  Light  Space  Water  Nutrients Animals compete for such things as:  A mate  Territory  Food  shelterMonday, April 30, 2012 Mr G Davidson 19