Which biodiversity metric measures how evenly individuals are distributed among species?

• A. Evenness
• B. Species richness
• C. Diversity index
• D. Abundance

Answer: (A)

Evenness focuses on how evenly individuals are spread across the species present. If every species has about the same number of individuals, evenness is high; if one species dominates and the others are rare, evenness drops. This is exactly what the metric called evenness captures, often expressed through measures like Pielou's evenness. The reason this fits the question is that you’re looking for a way to describe distribution of individuals among species, not just how many species there are. Species richness counts how many species exist, ignoring how those individuals are distributed. A diversity index, such as Shannon or Simpson, blends richness and evenness into a single number, reflecting overall diversity rather than focusing solely on distribution balance. Abundance refers to the total counts of individuals or per-species counts, which doesn’t alone describe how those counts are shared among species. So evenness is the best descriptor of how evenly individuals are distributed.