Supplementary Figure 1: Pigment cell clones vary in size and cellular composition.

(a–o) Cre-lox induced clones (red) in the juvenile skin (¿14 mmSL) of Tg(sox10:ERT2-Cre); Tg(actin2:loxP-STOP-loxP-DsRed-express) animals label various cell types. (a–b) Examples of small clones with only iridophore labelling, (c–g, k–l) typical mixed clones with iridophores and variable numbers of melanophores, and (i–j) small clones with only melanophore labelling. Iridophore clones in (a,b) are restricted to the first interstripe along the D-V axis, clones in (d–g,l) extend both dorsally and ventrally, clones in (h, k) cover the skin predominantly ventrally whereas clone in (c) predominantly cover the skin dorsally of the first interstripe. Labelled pigment cells of the scales can be seen in (d, e, l). (n—r”) Different kinds of pigment cells can be identified by their distinct shape, location, and pigment content. (n–n”) a single labelled melanophore in the stripe of a juvenile shows characteristic morphology and black pigment (arrow in n’). (o–o”) Dense iridophores are located in the interstripe (arrowheads). (p–p”) loose iridophores and (q–q”) L-iridophores are located in the stripe region and are close to the melanophores. (r–r”) Xanthophores have distinctly different morphology and packaging in the interstripe compared to the dense S-iridophores. Scale bar: 100 m. (s) The majority of the iridophore clones span two to four segments along the anterior-posterior axis (79%, n = 136 clones) and (t) more than one stripe along the dorso-ventral axis (87%, n = 163 clones). (u) Labeling of iridophores in the new interstripes is strongly associated with labeling of iridophores in the first interstripe (93.6%, n = 142 clones). (v) Frequency of association of iridophores with the DRGs.