题目选项分析

The Aquipos toucan is able to use its long beak to reach inside apertures in a tree's bark and feed on the insects that dwell within and that are the toucan's main food source. Several noted ornithologists have speculated that because the toucan's beak is curved in a manner similar to the openings in the bark, the beak evolved so that the toucan can best take advantage of the insects lying deep inside.

Which of the following, if true, argues most strongly against the ornithologists' speculation?

【选项】Subtle gradations in the beak's of other species of birds have allowed them to better access resources in their respective environments.