Evolution of pigment patterning in Danio species

Pigment patterns are very prominent features of many animals. Their functions range from thermo-regulation and UV protection, to inter-and intra-species communication, e.g., camouflage, aposematism or species recognition. Due to a number of advantages the zebrafish (Danio rerio) has become one of the leading vertebrate model organisms to study pigment patterning in recent years. The pattern of the adult fish is highly conspicuous and very reproducible from one fish to another; it is made up from three different types of pigment cells,melanophores, xanthophores and iridophores, that arrange into horizontal light and dark stripes in the skin of the fish. Several mutants are known with disrupted patterns, they allow the identification of genes controlling the process. Other Danio species, which are closely related to zebrafish, show an amazing variety of different pigmentation patterns, ranging from horizontal stripes and spots to vertical bars and almost no pattern at all. Based on our knowledge of the patterning process in zebrafish we recently began to investigate the evolutionary changes that lead to this stunning diversity of pigment patterns in the Danio-species group. We established breeding colonies of several additional Danio species in the lab and started to produce hybrids and gene knock-outs to investigate the genetic changes that underlie the evolutionary diversification of pigment patterns in this group of fish