Figure 1. Calculation of the Relative taxonomic resolving power index (R_tax) and Taxonomic index of congruence (C_tax).

Calculations are exemplified on two distinct species delimitation approaches (X and Y) supporting different taxonomies. For a better understanding, calculations are first exemplified on a tree-based taxonomy (a). Although these calculations are based on a underlying phylogenetic perspective, knowledge of tree topology is not mandatory to perform the calculations (b). In (a), speciation event hypotheses supported by the approaches X and Y are represented by black and white circles, respectively. The C_tax between both approaches is defined as the ratio of the total number of speciation events congruently supported ( = shared) by both approaches (dark grey boxes), relative to the total number of speciation events cumulatively suggested by both approaches (in light grey boxes). The R_tax of a given approach represents the proportion of speciation events that it supports ( = single), relative to the complete set of speciation events (set of boundaries cumulatively revealed by all the different approaches – only two approaches in this example). In (b), representing the same taxonomy, the same calculations have been performed without relying on a phylogenetic tree, the number of speciation events being indirectly inferred from the number of species (in a dichotomic species tree, N cladogenetic speciation events = N species – 1). Little black dots represent specimens or populations, and each colored oval represents a distinct species hypothesis according to the approach (or combination of approaches) used.