Practice question

Alpha diversity describes richness and abundance within a single local community, whereas beta diversity describes compositional change among communities. Thus, identifying the region labelled Q as having maximum alpha diversity requires Q to contain the richest local assemblage, or the assemblage with the greatest combined richness and evenness if an index is supplied. Identifying S as having maximum beta diversity requires the greatest species turnover among its sampled sites: sites in S should share relatively few species and differ strongly in composition. Beta diversity is not simply the total number of species in a region; a region may have high gamma diversity but modest beta diversity if every site contains nearly the same species. Conversely, environmentally heterogeneous regions can have high beta diversity because different habitats filter different species. The pairing Q and S therefore expresses two distinct spatial properties—high diversity within a site and high differentiation between sites. The underlying diagram or species table is needed to recompute these rankings, but the conceptual basis for the keyed pairing is local diversity in Q and maximum turnover in S.