What is the action of natural selection? Is it possible to obtain experimental confirmation

1. What is the action of natural selection? 2. Is it possible to obtain experimental confirmation of the effect of selection? 3. What leads to the struggle for existence? 4. What forms of struggle for existence do you know?

In natural selection, the selection factor is the conditions in which the organisms are found. If organisms have a number of properties that adapt them to them, then they will continue their kind – give more numerous offspring with adaptive characteristics.
The selection effect can also be confirmed experimentally. For a simple experiment, organisms (insects) with different colors can be placed in an open area against a background of a certain color. And repeating this experiment many times, you can make sure that those insects that have a masking color (in the background color) will survive, and the rest will be pecked by birds.
The fact is that each organism is capable of recreating a huge number of offspring. But this is not happening due to the lack of vital resources. It is this deficit that leads to the struggle for existence.
There are three forms of struggle for existence: intraspecific struggle (considered the most acute because of competition for similar resources of life), interspecific struggle (an example is the predator and prey), and the struggle against unfavorable living conditions (for example, conditions in Antarctica).