Evaluation of the fit of the macroscopic ecological description of the island and the functional metrics based on null modelling-based. Each histogram was calculated after 999 replicates with a sampling number equal to the island richness (Table 1, number of species). Black lines represent observed metrics. Red lines represent the mean value of the random sample for each island. The estimated standardised effect size is reported within each chart, being this test only significant for Tenerife. The results and complex and affected by the geological characteristics of each island. Nevertheless, observed values of evenness are larger than estimated values in the mature islands of La Gomera, Tenerife and Fuerteventura, where diversity is driven by community interactions, whereas they are smaller in those islands where extinction and speciation play a more important role. Estimated richness values of richness are larger than observed values in mature islands