How evolution shapes color diversity in coral reef fish

Scientists have long wondered why coral reef fish display such extraordinary diversity in colors and patterns, including stripes, spots, and complex markings. A study by the University of Liège analyzed whether these patterns were shaped mainly by local environmental conditions or by broader evolutionary rules. By examining pigmentation patterns in 918 species across six major reef fish families and five global ocean regions, researchers discovered that pattern diversity increases with the number of species living in a region. This suggests that the process of speciation and the need for fish to visually recognize members of their own species play a larger role in pattern diversity than environmental differences between oceans.

The researchers also found that color patterns in reef fish evolve quickly but within a limited set of possibilities. While species rapidly explore different visual designs, the types of patterns that can form are constrained by biological mechanisms involved in producing pigmentation. Because of these constraints, unrelated fish species living in completely different oceans can sometimes develop very similar patterns. This phenomenon is known as evolutionary convergence, where different species independently evolve similar traits.

These constraints are thought to come from cellular and developmental processes that control how pigment cells form patterns during growth. As a result, reef fish patterns are shaped not only by external factors such as predators or habitat but also by internal biological rules that limit the range of possible designs. The study highlights that the vibrant appearance of reef fish reflects deeper evolutionary processes—driven by speciation, shared developmental mechanisms, and convergent evolution—rather than simply local environmental pressures. To learn more, read University de Liege's article How evolution shapes color diversity in coral reef fish