It is the earth's relationship to the sun, and the amount of light it receives, that is responsible for the seasons and biodiversity. The amount of sun a region receives depends on the tilt of the earth's axis and not its distance from the sun.
The seasons are caused by the direction Earth's axis is pointing relative to the Sun. The Earth revolves around the Sun once each year and spins on its axis of rotation once each day. This axis of rotation is tilted 23.5 degrees relative to its plane of orbit around the Sun.
