IB ESS HL 3.1.8 Simpsons Reciprocal Index Question Bank

Calculate and interpret Simpsons reciprocal index as a measure of biodiversity.

Exam points

identify the biodiversity or evolutionary process
apply the correct diversity, selection or conservation concept
justify the conclusion with evidence and ecological reasoning

[Maximum number: 4]

Outline how species diversity in an ecosystem can be measured.

species diversity in communities is a product of two variables: the number of species (richness) and their relative proportions (evenness);
b. name an appropriate index, e.g. Simpson's diversity index / Shannon's index;

To calculate Simpson's Index:
c. the area must be sampled, e.g. using quadrats placed randomly or systematically/pitfall trap/mark-recapture;
d. several samples need to be taken and the data pooled (to give a better estimate of overall diversity);
e. the number of individuals of each species (abundance) should be noted in each sampling plot;
f. there is no necessity to be able to identify all the species, (provided they can be distinguished from each other);

D=\frac{N(N-1)}{\sum n(n-1)}

g. calculate diversity index by using a valid formula, like
n= the total number of organisms of a particular species
N= the total number of organisms of all species
[Note: credit only if all symbols are explained; accept different formulas as found in literature]
h. with this index, the higher the value of D, the higher the species diversity;

Note: Accept any other relevant measurement to those given.
Do NOT credit Lincoln's index formula.

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3.1.8—Simpson's reciprocal index question 1