Calculate the Simpson's Diversity Index of a community of 10,000 organisms equally distributed in 10 species. Is this community more or less diverse than a community of 2,000 organisms equally distributed in 20 species?



Answer :

To calculate the Simpson's Diversity Index for two different communities and determine which one is more diverse, we can use the following steps:

### Community 1
Total organisms: 10,000
Number of species: 10

1. Calculate the proportion of each species in the community.
- Since the organisms are equally distributed, each species has:
[tex]\[ \text{Number of organisms per species} = \frac{\text{Total organisms}}{\text{Number of species}} = \frac{10000}{10} = 1000 \][/tex]

2. Calculate the proportion of each species:
[tex]\[ p_1 = \frac{1000}{10000} = 0.1 \][/tex]

3. Compute the sum of the squared proportions:
[tex]\[ D_1 = \sum (p_1^2) = 10 \times (0.1^2) = 10 \times 0.01 = 0.1 \][/tex]

Simpson’s Diversity Index for Community 1 is 0.1.

### Community 2
Total organisms: 2,000
Number of species: 20

1. Calculate the proportion of each species in the community.
- Since the organisms are equally distributed, each species has:
[tex]\[ \text{Number of organisms per species} = \frac{\text{Total organisms}}{\text{Number of species}} = \frac{2000}{20} = 100 \][/tex]

2. Calculate the proportion of each species:
[tex]\[ p_2 = \frac{100}{2000} = 0.05 \][/tex]

3. Compute the sum of the squared proportions:
[tex]\[ D_2 = \sum (p_2^2) = 20 \times (0.05^2) = 20 \times 0.0025 = 0.05 \][/tex]

Simpson’s Diversity Index for Community 2 is 0.05.

### Comparison
The Simpson’s Diversity Index values are:
- Community 1: 0.1
- Community 2: 0.05

The lower the value of Simpson's Diversity Index, the higher the diversity of the community.

Hence, Community 2 (with an index of 0.05) is more diverse than Community 1 (with an index of 0.1).