Measuring Biodiversity
Biology: Cambridge International A Level, topic 18.1.6
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).
The equation
- The index of diversity (D) is calculated as:
- D = 1 - (\(\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.
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.
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.
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 = x 100
Test yourself on Measuring Biodiversity
What does 'N' represent in the equation for the index of diversity?
What is the equation for the index of diversity?
Which of the following statements are true about the index of diversity?
Which of these is the correct formula for calculating genetic diversity of a population?