Individuals in a large insect population display wide variation in the shape of their nectar-gathering mouthparts. A new food source, with flowers of different shapes, replaces the previous one, and insects with shorter, thicker mouthparts are much more efficient at gathering nectar from the new type of flower. Over multiple generations, what will likely happen to the variation of mouth parts within the population of insects?

Variation of mouth parts will decrease

Explanation:

It is given that the insect population has wide variation in shape of nectar gathering mouth parts. Without any disturbance this variation would continue to exist and would be passed on to subsequent generations.

Now the flower shape has changed which leads to efficient collection of nectar by shorter, thicker mouth parts. Insects with such mouth parts would be more competent than others and hence would thrive in population. They will pass on these traits to the next generations too and ultimately shorter, thicker mouth parts would be preferred over other types of mouth parts which will reduce the variation in population. However the variation would not completely cease to exist.