Consensus “clustering with noise” [21, 22] tree displaying Spanish linguistic varieties according to the Linguistic Atlas of the Iberian Peninsula [18] as processed in [19].

The linguistic distance (1- RIW) is based on the relativer Identitätswert [30, 31]. Major clusters (see labels) discussed in the text are geographically displayed in Fig 7B. All branches having a score lower than 90 have been collapsed. Solid lines correspond to the result of the computational analysis, while dotted lines correspond to the position that Basque varieties (absent in the ALPI) would have had after a computational classification (see text for details). A simplified version of the tree is shown in Fig 3.