Adaptation is a property which occurs due to change in the environmental conditions of an organism. Some traits of organisms are not adaptation because sometimes the function of a trait changes due to evolution which we called exaptation. It also occurs due to hitchhiker effect, this effect occurs when the change occurs in the frequency of allele not due to natural selection but due to selective sweep with the nearby gene.
The soil and rocks in the zone of aeration have pores which are partially filled with water and air. The zone of saturation comprises rocks and soil whose pores are saturated with water. 3. The zone of saturation lies beneath the water table, while the zone of aeration lies above it.