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Simpson’s Diversity Index. To measure the diversity in an ecosystem. Simpson’s Diversity Index. Attempts to quantify the diversity (variety) of an ecosystem. There are two components: Evenness Richness. Evenness.
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Simpson’s Diversity Index To measure the diversity in an ecosystem
Simpson’s Diversity Index • Attempts to quantify the diversity (variety) of an ecosystem. • There are two components: Evenness Richness
Evenness • Evenness is a measure of the relative abundance of the different species within an area. (Same amount of each kind of organism) • When the numbers of each type of species is even, the value for the Simpson Diversity Index will be larger.
Richness = variety • Richness is a measure of the number of kinds of species • More species is “richer” so the value for the index will be higher.
The equation D = N(N - 1) n(n -1) D= diversity index N= total number of organisms of all species found n= number of individuals of a particular species
How to Calculate D: • Record the numbers of each species • Calculate n-1 for each species • Find the total number of organisms, N • Calculate the Simpson Diversity Index D = N(N – 1) n(n -1)
Calculate the Simpson’s Diversity Index for each sample Compare the evenness and richness of each sample.
Answers • Sample One: 2.99 • Sample Two: 1.15 • Both have the same richness as there are three species in each area. • Sample One is more even because the numbers of each kind of species are nearly the same.
A high value of D suggests a stable, complex and diverse ecosystem.
A low value of D could suggest pollution, recent colonization or agricultural management. Eukalyptus plantation Deforestation in Chile
Compare Simpson’s Diversity Index for a tropical rainforest vs a desert
Predict the value of the Simpson’s Diversity Index following pollution from copper mining.