Fortunately, the world is full of color. Many animals rely on vision to navigate their environment, and so color and pattern is a language used within and across species. But what about animals that hide underground to avoid being seen? Why would they need a rainbow of colorful coverings?
Evolutionary biologists are as fascinated by these phenomena as we are, and have sought to find theoretical and empirical explanations for the evolution of these traits. color It all started with a lucky coincidence: a random mutation in an individual’s genes gave it an unexpected advantage. survivereproduce, and transmit their mutations.
Some animals have furs withmysterious“Colors that blend into their environment. The tawny gazelles of the savannah and the dazzling camouflage of chameleonBy being less noticeable to predators, they increase their chances of survival and passing on their coloration.
Other species have “eye-catching” colors that stand out from the background. Bright colors These traits may be advantageous during sexual selection or may be alarming to potential predators, and in either case these traits will persist.
Crayfish are freshwater fish with over 700 species in existence. lobsterMany use “hidden” coloring to elude predators, but there are a staggering 400 species covered in blue, red, orange and purple. The problem is, these brightly colored crustaceans mainly live in muddy burrows and only come out at night.
This led Zachary A. Graham and his colleague Dylan J. Padilla-Pérez to ask: “Why are they so colorful if no one can see them?” There appears to be no evolutionary advantage to this phenomenon, but is it an evolutionarily neutral trait? This raises one of science’s toughest problems: proving there is no evolutionary pressure for colorful shells.
“Not all traits that exist are adaptive,” Graham said. Science“If we were perfectly adapted to our environment, we would never get infected, get sick, or die. But evolution doesn’t work that way.”
Using phylogenetic trees and photos of crayfish that had been dutifully color-coded by a group of crayfish biology students, the researchers found that conspicuous colors appeared more than 50 times. The evolution of these traits also correlated with the evolution of burrowing behavior.
An alternative hypothesis is also possible: that the tan coloration of some open-water crayfish arose as a result of evolutionary pressure to be more “conspicuous” and blend in with their environment. Researchers have found that conspicuously colored crayfish do not retain their coloration as they evolve underwater behaviors.
Mutations that give crayfish striking colors can occur quite frequently. If evolutionary pressure doesn’t prevent them, these lucky coincidences can spread throughout a population and cause crayfish coloring to change. crayfish Just for us.
This study Proceedings of the Royal Society B: Biological Sciences.
