Inheritance: The passing of one trait from parent to offspringOverproduction: When a species has to many offspring for the environment to handleSurvival of the fittest: A species will pass favorable traits to offspring to help them surviveDifferential reproduction: Those that survive because of certain traits will pass those traits to offspring
Survival of the fittest
There is a limited food supply
Trait Selected: Gray and SmallTrait Selected Against: White and BigType of Adaptation: PhysicalEnvironment/Environmental change: Predator and Food
Because the larger birds need more calories to survive, and food is scarce they will not survive. If you add a predator, the white birds will be more of a target because they are larger and stick out more than the gray small birds.
Because more small gray birds survive than white big birds, small gray birds have more offspring. This means the small and gray traits are passed on.