Evolution Problem?

Question

K... While Watching a Discovery Documentary that involved butterflys the narrator explained that some species extended their wings during some vulnerable moment and this showed a pattern that would simulate eyes, it did this in order to scare any predators lurking around and to get them thinking that it was really a bigger more vicious animal instead of a cute butterfly, then i fell into a buggin question:

How do species know what color to be? I know that they dont choose their color, we all are a product of our environment but, what the heck made the butterfly asimilate a pattern that resembled eyes on its wings? if it was an evolutionary accident how come the pattern is simetrical and it would even look like an iris and pupil? so it actually looks like it was designed, a Deer, how come the antlers simulate a dry bush? i mean many antilopes have horns for protection but some are straight and the more needed species disguise as their enviorenmnt? did it happen out of need?

Answer 1

Evolution is amazing.  If they didn't have these protective colorings, they'd be eaten by others more quickly.  They mate with others who have the preferred colorings, so those non-preferred colorings are weeded out.

Answer 2

Species don't "know" what colour to be, or what pattern to take. There is a misconception among some people that animals "decide" to evolve, that there is some will behind it, but, just as you say, that simply is not the case. The engine of evolution is natural selection, the environmental pressures of food, predation and mating, but the fuel that drives it is random mutation. Every one of us is the combination of genes from our parents, but also of 120 or so random mutations. Most mutations have no effect, some are deleterious, and some are beneficial. Natural selection acts on the random variation of individuals, where those individuals who are stronger, faster, able to compete with peers for mates, more able to catch prey, or to evade predators by running or by blending into their environment. Mutation may be random, but selection for those mutations is anything but random. Individuals with traits that give them an advantage are more likely to live to breed and pass on those traits to their offspring, and gradually, over many generations, the genes that confer those traits become fixed in the population as a whole. Deer antlers are an example of a trait that is primarily advantageous for mating - we've all seen the nature documentaries where male deer clash antlers, and the stronger gets to mate with the female.

Colouration is a particularly interesting area of evolution. Some animals develop colours and patterns that blend in with their surroundings, which obviously confers an advantage of not being spotted by predators, or allowing their prey to spot them. Some animals are brightly coloured as a direct warning of their toxicity, such as poison dart frogs and coral snakes - potential predators learn to stay away from them as attempting to attack or eat them means bad news. And then there are animals that have evolved to mimic poison colour warnings without actually being venomous or toxic themselves - they are essentially "borrowing" the efforts of genuinely toxic creatures, following in their footsteps.

Butterfly wing patterns are in some sense a combination of deer antler and warning pattern (sometimes false, sometimes genuine - some butterflies are poisonous to birds) - they serve to identify and attract mates, and to ward off predators. Scientists have studied the genes responsible for the formation of wing patterns and found them related to the genes for eye pigmentation in insects. They have even been able to artificially manipulate wing patterns to study mutations in the laboratory. Fascinating stuff indeed.

Additional edit:

The DNA doesn't "understand" to form a pattern like an eye. It doesn't understand anything, it's just a big long polymer. A random mutation happens to produce an eye-like concentric ring pattern, which happens to look particularly fearsome to the butterfly's predators thus increasing that individual's likelihood of survival. As the first and third sources listed explain, wing patterns are produced and manipulated by a very limited number of genes. Therefore it takes only minor changes to those genes to produce radically different wing colouration and patterns. This accounts for the wide variety of different wing patterns on various species of butterfly - when they do get to roll the "dice" of mutation in those particular genes, a lot of variation is produced. That some of those "dice rolls" happened to throw up concentric ring patterns is not surprising, and that those patterns stuck in their genome shows natural selection favoured those patterns.

Answer 3

Think of it like this:

natural selection. You have animals of all varying colours and shapes. The ones that have a certain scary pattern that goes with a habit of opening their wings at a vulnerable moment, scare off predators. The ones that don't have the pattern, or the behaviour, get eaten.

So in the next generation, the scary-pattern wing-opening individuals are more common and they get to breed, mostly with each other because there are more of them. The ones lacking the pattern and reaction are still being eaten.

That's why it's called natural selection: you either reproduce or die.

Answer 4

There is no choice involved, it is a matter of which animals are able to reproduce the most.  So, over hundreds and hundreds of years the butterflies with the patterns most like eyes lived the longest and reproduced more than the rest.  

In some species of birds, there have been studies where the length of the tail feather is a fine balance between attractiveness and survival.  The longer the tail feather, the more attractive the male is to the female.  The shorter the tail feather, the longer the male will live because he can fly faster.  So the average length is a balance between the ones that live longest and the ones that are most attractive to mates.  It can be hard to turn the thinking around the right way, I hope that makes a little sense!

Answer 5

Because they were "made" that way. There is no way evolution accidently made wings that look like eyes, when eyes themselves are supposedly an accident as well. ; )