Why are interactions with the environment important to adaptation and variation

For a species to "adapt" to the environment it needs to interact with it. Interactions allow for individuals with lower survivability to that environment to get weeded out by competition, predation ect. This allows organisms with traits that suit the environment better to survive, reproduce and the species adapts to the environment. Without the environment a trait cannot adapt because there is no natural selection.

An environment can be changing- ie cold winter warm summer. Certain individuals will be better suited for winter or summer depending on genetic traits. If the environment isn't variable their wou