Community 1 contains 100 individuals distributed among four species: 5A, 5B, 85C, and 5D. Community 2 contains 100 individuals distributed among three species: 30A, 40B, and 30C. Calculate the Shannon diversity (H) for each community. Which community is more diverse?

Verified step by step guidance

1. Calculate the proportions of each species in each community. For Community 1: pA = 5/100 = 0.05, pB = 5/100 = 0.05, pC = 85/100 = 0.85, pD = 5/100 = 0.05. For Community 2: pA = 30/100 = 0.3, pB = 40/100 = 0.4, pC = 30/100 = 0.3.
2. Apply the Shannon diversity index formula: H = -\sum (p_i \times \ln(p_i)), where p_i is the proportion of each species.
3. Calculate H for Community 1: H1 = -(0.05\ln(0.05) + 0.05\ln(0.05) + 0.85\ln(0.85) + 0.05\ln(0.05)) = 0.544.
4. Calculate H for Community 2: H2 = -(0.3\ln(0.3) + 0.4\ln(0.4) + 0.3\ln(0.3)) = 1.029.
5. Compare the Shannon diversity indices: H1 = 0.544 and H2 = 1.029. Community 2 is more diverse than Community 1.

Key Concepts

Shannon Diversity Index

The Shannon Diversity Index (H) is a mathematical formula used to quantify the diversity of a community. It takes into account both the number of species and the evenness of their distribution. The formula is H = -Σ(p_i * ln(p_i)), where p_i is the proportion of individuals belonging to species i. A higher H value indicates greater diversity.

Species Richness

Species richness refers to the number of different species present in a community. It is a simple count of species and does not consider the abundance of each species. In the context of the question, Community 1 has four species while Community 2 has three, which contributes to the overall diversity assessment.

Evenness

Evenness measures how evenly individuals are distributed among the different species in a community. It is an important component of diversity, as communities with a few dominant species and many rare ones have lower evenness. In calculating the Shannon diversity, both species richness and evenness are considered to determine which community is more diverse.