The natural selection is the process by which the organism that best suits the characters will survive and the organism which cannot adapt the changes will die.
The predators feed on their prey and the organism which hides easily in the environment due to its color is safe and the animals that cannot camouflage will die.
This is natural selection that more favored character is carried out over generations and other that cannot survive die.
Resistance is directly proportional to voltage so when you increase Voltage resistance will also increase in order to keep the rate of flow of charge (current) constant