Abstract
Mankind finds the colours, the patterns and the songs of animals beautiful, just as we do works of art, paintings and music. Our works of art are created by humans for humans, but what about the wonderful works of nature, the ornaments and sounds of animals? Why and for whom are they there? How do they arise?
Animal colour patterns have important functions in communication among individuals of a species, for example recognition and selection of a mating partner, or attraction of many individuals to form large groups. Colour patterns also serve as deceptive signals that are recognized by individuals of different species. Moreover, colour patterns are highly variable and evolve rapidly leading to large diversities even within a single genus. In short, colour patterns are of high evolutionary relevance as targets of natural as well as sexual selection.
How insects, beetles, flies and butterflies develop their colours is reasonably well known, but in vertebrates many things about it are obscure. With mammals and birds, critical steps in the development of colour patterns are hidden either in the mother's belly or in the bird's egg. We do, however, now know a lot more about these processes in fish, which display a multitude of beautiful patterns composed of a mosaic of differently coloured cells in the skin. The characteristic stripe pattern of the zebrafish Danio rerio serves as a model for the development and evolution of animal colour patterns.
References:
Nüsslein-Volhard and Singh 2017: How fish colour their skin: a paradigm for development and evolution of adult patterns. Bioessays 39:1600231
Nüsslein-Volhard 2019: Animal beauty: Function and Evolution of Biological Aesthetics. MIT press
