18.1.6

Measuring Biodiversity

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Index of Diversity

Biodiversity can be measured using Simpson's Index of Diversity. The index of diversity uses the number of species (species richness) and the number of individuals in each species (species evenness).

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The equation

  • The index of diversity (D) is calculated as:
    • D = 1 - ((n(n1)N(N1)))((\large\frac{\sum n(n-1)}{N(N-1)}))
      • N = total number of organisms of all species present.
      • n =total number of organisms of one given species present.
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Benefit of using this index

  • The benefit of using the index of diversity instead of just species richness is that it takes into account the population sizes of different species in one community.
    • The greater the value for the index of diversity, the more diverse the community.

Assessing Genetic Biodiversity

Genetic diversity is about the number of different alleles that can be found at a given gene locus within a population. The genetic diversity of an isolated population can be calculated.

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Genetic diversity

  • The greater the genetic diversity, the greater the number of different alleles at a given locus there are, coding for different variations of a characteristic.
  • Within a population, the higher the percentage of gene loci that can have different alleles, the greater the genetic diversity.
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Calculating genetic diversity

  • Genetic diversity can be calculated by working out the proportion of polymorphic gene loci compared to the total number of gene loci and giving this as a percentage.
    • Genetic diversity = number  of  polymorphic  gene  locitotal  number  of  loci\frac{number \;of\; polymorphic\; gene\; loci}{total\; number\; of\; loci} x 100

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1Cell Structure

2Biological Molecules

3Enzymes

4Cell Membranes & Transport

5The Mitotic Cell Cycle

6Nucleic Acids & Protein Synthesis

7Transport in Plants

8Transport in Mammals

9Gas Exchange

10Infectious Diseases

11Immunity

12Energy & Respiration (A2 Only)

13Photosynthesis (A2 Only)

14Homeostasis (A2 Only)

15Control & Coordination (A2 Only)

16Inherited Change (A2 Only)

17Selection & Evolution (A2 Only)

18Classification & Conservation (A2 Only)

19Genetic Technology (A2 Only)

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