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Environmental Biology & Genetics
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  1. Environmental Biology & Genetics Factors Affecting the Variety of Species in an Ecosystem. Mr G Davidson

  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”. Mr G Davidson

  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.. Mr G Davidson

  4. Darwin’s Finches Charles Darwin investigated the finch population of the Galapagos Islands in the 1830s. 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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  7. Biodiversity • Biodiversity is very important to humans in a number of different ways: Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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 leopard Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  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. Mr G Davidson

  19. Competition • Plants compete for such things as: • Light • Space • Water • Nutrients • Animals compete for such things as: • A mate • Territory • Food • shelter Mr G Davidson