There are not five "postulates" of natural selection, but rather four principles that Charles Darwin outlined in his theory of evolution by natural selection. These are:

1. Variation: Individuals within a population exhibit variation in their traits.

2. Inheritance: These variations are heritable, meaning they can be passed down from parents to offspring.

3. Overproduction: Organisms produce more offspring than can survive.

4. Differential survival and reproduction: Individuals with traits that make them better suited to their environment are more likely to survive and reproduce, passing on those favorable traits.

These four principles work together to drive the process of natural selection, leading to the gradual evolution of populations over time.