Imagine a field of flowers; a field of flowers that are pollinated by basically three different pollinators. one pollinator, bees, attracted to short plants. another, butterflies, prefer plants of medium height and a third pollinator, birds, visits only the tallest plants. pesticide spraying kills many insect pests in the field of flowers but also wipes out the butterfly population. if the pollinator that preferred plants of medium height, the butterflies, disappears from the area, medium height plants would be selected against and the population would tend toward both short and tall, but not medium height plants. such a population, in which multiple distinct forms or morphs exist is said to be polymorphic. this is also an example of selection.