Dazzling as it often seems, fashion in the animal world can be frighteningly repetitive. Among the grays and greens of leaves and mud, there are many color patterns that scream “look at me.”
Therefore, it should not be surprising that animals use the same colors for very different purposes.
The bright blush of a male northern cardinal (Cardinalis cardinalis) serves as a signal for the approach of potential mates; in strawberry poison frogs (Oophaga pumilio), that red burst is a stern warning to stay away, otherwise one mouthful is potent, deadly toxin.
Zachary Emberts, an evolutionary biologist now at Oklahoma State University, and John Wiens, a colleague at the University of Arizona, wondered what caused the same colors to evolve for such different purposes in different animals.
They studied 1,824 species of land vertebrates (aquatic animals may be completely different). fish kettle), categorized their colors as either get here or get lost, and found a common thread connecting each group.
Animals that come here, such as birds and lizards, are descended from diurnal or diurnal ancestors. Lost animals such as snakes and amphibians come from nocturnal ancestors.
“The characteristics we see in species today may be the result of their evolutionary history.” says Emberts. “We were looking for patterns of evolution, so we did two separate analyses, one using their current day-night activity and one using their ancestor’s day-night activity.”
They found that there was no correlation between day and night activity and the coloration of the animals during the day; instead, the link is purely ancestral. But it appears to be consistent across all terrestrial vertebrates, whose evolution dates back to about 350 million years ago.
“It doesn’t matter how a species produces colors” Wiens says. “A bird’s red coloring is different than a lizard’s red coloring, but this general pattern of day-and-night activity still works.”
According to the researchers’ analysis, most of the ancestors of the animals they studied started out quite simple and dull, developed their vivid colors over time, and most of them live in environments where their vivid colors stand out. The most plausible explanation is that animals with brighter colors were better able to survive and pass on their genetic material to generations that continued this trend.
The colors analyzed included red, orange, yellow, purple, and blue, and the researchers found that for all colors except blue, the colors were pretty evenly split between sex signal and warning. It is not yet clear what could be the reason for this.
“It is interesting to see that some colors, such as red, orange and yellow, are used with equal frequency to avoid predators and to attract a mate.” says Emberts.
“On the front side, the color blue was more often associated with mating, as opposed to avoiding predators.”
The coloration of diurnal animals makes sense: a bright animal will be seen by other animals, including potential mates, in daylight. This may make them bigger targets for predators, but it seems that finding a mate and reproducing is more important than not eating. Females of these species are often puny in comparison and are therefore better able to hide from predators and survive to posterity.
But nocturnal animals slither in the dark. Male night snakes do not use bright color as a sexual signal unless females can see it.
“Warning colors have evolved even in eyeless species” Wiens says. “It’s questionable whether snakes or most amphibians can see color, so their bright colors are generally used to signal predators, not conspecifics.”
Instead, the researchers suggest, the coloration may have evolved as a way to signal to daytime predators that might befall the sleeping animal to stay away. But future research may reveal more details. The team hopes to delve deeper into the evolution of bright colors to see if their function has changed over time.
However, research shows that looking at the evolutionary history of animal traits can reveal patterns that are no longer relevant today.
The team’s research was published Evolution.
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