Natural+Selection+&+Why+It+Isn't+Perfect

Natural Selection & Why It Isn't Perfect One would think over time that natural selection would produce the perfect organisms. Well, it can't, and here are the reasons why:

1. Evolution is limited by historical constraints
 * Natural selection can't just 86 one species and supercharge it with another one. Each species has ancestors and throughout time NS will take anatomical structures and mold and shape them into new species.

2. Adaptations are compromises
 * A great relationship is full of compromises. So are species. An organism may be great at something and have all the parts it needs for that activity, but it may have other parts that hinder that activity. It's all about the trade-off.

3. Chance and natural selection interact
 * Unexpected things happen all the time, the most obvious example being Mother Nature herself. Hurricanes and tornadoes and fires interact with species in ways that could possibly affect their descendants, such as blowing a swarm of bugs thousands of miles away from its natural environment.

4. Selection can edit only existing variations
 * Survival of the fittest is true, but sometimes, those traits may not be most desirable in the situation. New alleles in organisms can't pop up on demand.

(1) All information taken from AP Edition Biology, Seventh Edition, Campbell and Reece