Communities & Measuring Diversity
Biology: IB Diploma Higher Level, topic 8.1.2
Index of Diversity
Populations rarely, if ever, live in isolation from populations of other species forming communities. The diversity of communities can be assesed using Simpson's Diversity Index.
Communities
- In most cases, numerous species share a habitat.
- The interactions between these populations play a major role in regulating population growth and abundance.
- All populations occupying the same habitat form a community: populations inhabiting a specific area at the same time.
- The number of species occupying the same habitat and their relative abundance is known as species diversity.
- Ecology is studied at the community level to understand how species interact with each other.
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.
Test yourself on Communities & Measuring Diversity
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?