Fig. 1.2. A conceptual illustration of diversity patterns on a mountainside. The circles represent study sites, and the letters represent the individual species present. In this example, alpha diversity—the number of species within each site—decreases with altitude. There is little overlap in species composition among sites; therefore, beta diversity is high. This indicates species specialization in response to a strong environmental gradient. Gamma diversity is the total number of species on the mountain (i.e., 12).
