This poison dart frog's bright yellow skin gives it a warning color. Yellow not only warns, but can also attract mates in some species. Why don't similar colors in the animal kingdom automatically mean the same thing?
Scientists working with Zachary Emberts and John Wiens from the University of Arizona have now answered this question: whether a species uses its bright colors to deter predators or to find a partner apparently depends on whether its ancestors were diurnal or nocturnal. Species that beguile partners with their bright colors are therefore mostly descended from diurnal ancestors. On the other hand, animals that warn predators with their colorful clothing have nocturnal ancestors.
As the scientists explain, this could be for the simple reason that bright colors such as red, orange, yellow, blue and purple only offer an advantage when mating during the day. Only then can the potential partners even see them. Animals that are active at night and also mate in the dark may instead use the colors for another purpose: as a warning signal to predators. Because these predators are also a danger during the day, when the nocturnal animals are resting and are therefore easier to attack. The warning dress then indicates that they are poisonous or inedible.
"This pattern seems to apply to all terrestrial vertebrates in general," explains Wiens. According to the researchers, lizards and birds therefore usually use their colorful scales and feathers as a sexual signal when choosing a mate. Amphibians and snakes, on the other hand, generally use them as a warning to predators. According to the team, whether they themselves are active during the day or at night has nothing to do with this distribution. It's just about what time of day the ancestors of the brightly colored species roamed through their habitat.