Practice question

For S equally abundant species, every relative abundance is 1/S and Shannon entropy simplifies to ln(S). With twenty species, ln(20) is about 2.996, which rounds to approximately 3 using natural logarithms. Diversity has separable richness and evenness components. Shannon entropy rises when species number increases or abundances become more equal, while Pielou evenness scales Shannon entropy against the maximum possible value for that richness. Simpson measures emphasize the probability that sampled individuals belong to the same or different species, depending on convention. Every calculation therefore requires explicit relative abundances and a stated formula; comparing values produced under different conventions can reverse interpretation. In this context, the keyed term, 3, identifies the relevant mechanism or quantitative relationship and links the observed pattern to its underlying ecological cause. The distinction is testable by measuring changes in organisms, resources, or process rates through time rather than relying on the label alone. This interpretation connects the formal definition to an observable ecological pattern.