Biodiversity can be measured by looking at the number of different species in a community (richness) and how evenly they are distributed (evenness). By analyzing rarefaction curves, scientists can understand both richness and evenness. They found that the slope of the steepest part of a rarefaction curve is related to evenness. This relationship can also help interpret species-area curves. By using these techniques, researchers can evaluate diversity at both local and regional levels.