This is known as aversion therapy. Here, a patient is concurrently exposed to a stimulus, typically an addiction, and some form of discomfort. The idea behind this is that the patient will associate the addiction with unpleasant experiences. In this way, it is hoped that the patient will overcome his/her addiction. This sort of therapy has taken many forms. The more common form is for example to paint unpleasant-tasting nail polish on one's nails to discourage nail chewing. More extreme forms include electric shock therapy.
This is called incomplete dominance. When an something is heterozygous for an incomplete dominant gene, the resulting phenotype will be somewhere between the two. For example if a plant has a tall allele and a short one, but neither shows complete dominance over the other, the plant height will be somewhere in the middle.
Answer:
The average trait value changed in one direction.(In this case, larger size)
Explanation:
In evolution a natural selection can be disruptive, directional or stabilizing
In stabilizing no extreme trait is favored hence provides intermediate values .
Disruptive selection both extreme traits are favored over the intermediate trait.
Directional, the enviroment will favor the survival of one trait hence a change in direction either towards the left or the right.
In the case of swallow cliff mortality, selection favored the larger size.