Different developmental roads to similar pigment cells

A new study from the Milinkovitch-Tzika lab by Pierre-Yves Helleboid and Athanasia C. Tzika, published in Nature Communications, investigates how pigment-producing cells — chromatophores — differentiate during reptile embryonic development. Using single-cell gene-expression analyses, the researchers followed the development of chromatophores in two evolutionarily distant reptiles: the corn snake (Pantherophis guttatus) and the bearded dragon (Pogona vitticeps).

The team identified the three canonical chromatophore types — melanophores, xanthophores and iridophores — in both species. In the bearded dragon, however, they also discovered previously undescribed chromatophore subtypes that simultaneously express markers of progenitor and mature cells and may contribute to the establishment of the embryonic skin colour pattern.

Comparing these developmental trajectories with those of fish and amphibians revealed an intriguing evolutionary pattern: mature pigment cells are remarkably similar across species, reflecting their shared functions, whereas their progenitors can rely on substantially different transcriptional programmes. In other words, evolution can modify the developmental route while preserving a similar cellular destination.

These results highlight both the conservation and the evolutionary flexibility of the mechanisms that generate vertebrate cell-type diversity, while providing new insights into the spectacular diversification of reptile coloration.

Original article

Conserved and lineage-specific mechanisms drive chromatophore differentiation in reptiles
Pierre-Yves Helleboid & Athanasia C. Tzika
Nature Communications 17, 8368 (2026).