The study looked at how changes in the number of species, their evenness, and their total abundance are related in different ecosystems. By analyzing over 1100 groups of species, the researchers found that when the number of species and their evenness changed in the same way, there were more changes in overall species richness. However, when the number of species and their evenness changed in opposite directions, the changes in species richness were limited. They also found that changes in species richness and relative abundance were strongly linked over time, but not necessarily across different locations. Overall, changes in species relative abundances had a big impact on local biodiversity, and how these changes combined with total abundance determined the overall changes in species richness.