Figure 4-6 Examples of the spatial turnover and nestedness components of beta diversity, with four hypothetical locations (A-D), each with three sites. Location A is completely nested, as sites A2 and A3 each contain a subset of the richest site (A1). Location B is dominated by spatial turnover, as compositional differences are due to the introduction of new species across each site. Location C includes a combination of turnover and nestedness, as C2 and C3 have unique species relative to each other, but both sites contain a subset of what is found at site C1. Location D shows differences in richness across sites that are complete due to spatial turnover (unique species at each site). Figure reproduced from (Baselga 2010).

State of the Arctic Freshwater Biodiversity Report - Chapter 4 - Page 30 - Figure 4-6