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Biodiversity

Biodiversity. Tuesday, 07 May 2013. What do we understand by species diversity? How is Simpson’s Diversity Index used as a measure of species diversity?. Biodiversity. Species diversity: the number of different species and the number of individuals of each species within any one community.

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Biodiversity

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  1. Biodiversity Tuesday, 07 May 2013 What do we understand by species diversity? How is Simpson’s Diversity Index used as a measure of species diversity?

  2. Biodiversity Species diversity: the number of different species and the number of individuals of each species within any one community. Genetic diversity: the variety of genes possessed by individuals that make up any one species Ecosystem diversity: the range of different habitats within a particular area

  3. Species Diversity • Can be used to measure biodiversity • Two components: • Number of different species in a given area • The proportion of the community that is made up of an individual species

  4. Measuring species diversity

  5. Measuring species diversity The table on the previous slide does not show us much about the differences in the two habitats. In both cases the number of species and individuals are the same If we now calculate species diversity, then we get a different picture.

  6. Measuring species diversity d= N(n-1) . Σn(n-1) Where: d = species diversity index N = total number of organisms of all species n = total number of organisms of each species Σ= sum of

  7. Calculate the species diversity index of each habitat from the table on the previous slide. d= N(n-1) . Σn(n-1)

  8. Use this to calculate the species diversity index

  9. Now we can calculate the species diversity index: • Habitat X d = 50 (49) = 4250 = 5.44 450 450 • Habitat Y d = 50 (49) = 2450= 1.88 1300450 The higher the value, the greater the species diversity

  10. Tuesday, 07 May 2013 Species Diversity & human activities What is the influence of deforestation and the impact of agriculture on species diversity?

  11. The impact of agriculture

  12. Impact of agriculture Natural ecosystems develop from complex communities Agricultural ecosystems are carefully controlled by humans

  13. Farmers select crops that are more productive. The frequency of alleles is reduced For economic reasons, the crop yield needs to be large. Any one area can only support a certain amount of biomass – if most of this area is taken up by a crop, then there is little area left for anything else

  14. Crops are sprayed with pesticide and man made fertiliser. This further disadvantages and excludes species that the farmer does not want This all acts to reduce species diversity

  15. Impact of deforestation

  16. Impact of deforestation Forests contain many varied and different habitats = high species diversity Permanent clearing of the forest leads to loss of habitats and in turn loss of biodiversity What might you want to clear a forest for?

  17. You should be able to… Explain what we mean by species diversity. Explain how Simpson’s Diversity index is used to compare habitats Calculate Simpson’s Diversity when given the formula Outline the effects of agriculture and deforestation on species diversity

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