Fig. 2: Specialists tend to be of extreme sizes in regional faunas.

a, Map of all regions, defined according to zoogeographic realms identified by Holt et al.²⁸. b, The proportion (Prop.) of dietary specialists (points) declines in species of intermediate size. Species were grouped into ten bins, each representing 10% quantiles of average adult body mass (Supplementary Fig. 7). Panel a is plotted on the basis of data published in ref. ²⁸ (https://macroecology.ku.dk/resources/wallace, accessed on 20 June 2023). In b, the total number of species occurring in each region is indicated in the panel titles, and the proportion of specialists in each region (our realm-specific null expectation) is indicated by the dashed grey line. We considered proportions whose 95% binomial proportion confidence intervals (error bars) do not contain the region-specific null as significant deviations (solid points). In most regions, the proportion of specialists in both small and large size bins is relatively high; however, in Oceanian and Madagascan regions—primarily composed of island faunas—the largest size bins show significantly lower proportions of specialists than expected. See results from phylogenetic regression models in Supplementary Table 1.