Principle #1 Genetic Variation : Genetic Variation is a mutation that leads the population to looking different from each other . A change in the Phenotype . For example brown rabbits and white rabbits they are both rabbits but are a different color from each other .
Principle #2 Overproduction & the Struggle for Existence : The overproduction is that rabbits have offspring all year . A lot of them die cause they get eaten . The struggle for existence is that the brown rabbits can't camouflage in the white snow like the white rabbits can .
Principle #3 Differential Survival & Reproduction : The Differential in survival is that the brown rabbits are getting eaten at a much higher percent then the white rabbits . The white rabbits have a higher fitness so they are able to reproduction more offspring then the brown rabbits .
Principle #4 Changes in Gene Pool : Lets say that the number of white rabbits was equal to the number of brown rabbits . Brown rabbits are dying off very fast so they don't reproduce offspring . Since white rabbits have a favorable trait they have a higher fitness level which lets them reproduce offspring and since there offspring will have the favorable trait they will reproduce and that's how a gene pool changes over time .