Natural Selections Works its Magic
Evolution Goal 2
Evolution of the Eye
Evolution skeptics often bring up the evolution of the eye. How could this complex organ with so many different parts have evolved? By using modern day creatures as examples scientists can explain every step of the human eye's evolution. It started with a simple eye that could only detect movement. This would have giving the animal a small advantage over the others of its species to detect predators. The eye then would have developed a ball like shape with a small hole (or pupil) then adding a lens. All of this, for clearer vision and each step producing more and more of an advantage to each animal.
Genetic Variation it helpful towards the evolution as a species creating small individual variations that can help, harm, or neither a creature. If one organism within a species had a slight advantage (faster, brighter, smarter,etc.) they will have a higher chance of their genes passing on to off spring and those offspring being genetically stronger. Over generations the entire species would evolve to have that small advantage making the speices stronger as a whole.
In nature, scientists have discovered a trade-off between versatility and performance when the organs have evolved to do more than one job. Organisms will sometimes evolve structures or behaviors that are compromise solutions to the environment they live in. In other environments this advantage would be dangerous or harmful for the organism. The evolution of camouflage is an example of this principle. The camouflage that helped an organisms blend into a tree stump and has an advantage in that environment, would be dangerous in an environment with bright colors everywhere. The organism would be more likely to be eaten in the environment with the bright colors than its original environment in which it would be safer for the animal.
Sexual reproduction is often more favorable in the animal kingdom even though it requires more energy and can be more dangerous to the organism participating in it. Scientists believe that this is due to the fact that sexual reproduction allows for more genetic and individual variation in an organisms, instead of asexual reproduction where the offspring is an exact genetic replication of the parent. Individual genetic variation is an advantage for an animal because it makes it very difficult for parasites and bacteria to harm the animal. The parasites and bacteria have to slightly change every time it enters a new host in order to harm the animal, where as with asexual species they are all genetically identical and it would be very easy for parasites and bacteria to harm the entire species very quickly.
When Darwin was in the Galapagos islands he noticed the many different types of finches along with their different diets. The finches differed in color and the shape of their beaks. Darwin proposed that all the finches derived from a common ancestor yet when one was born with a different beak it allows that finch to eat from a different food source that the others could not. Over time the finches evolved to have many different diets and many different beaks that allowed them to eat from their specific source of food.