Evolutionists must distinguish between adaptations an organism acquires during its lifetime and those inherited adaptations that evolve in a population over many generations as a result of natural selection. In wet years, birds preferentially feed on small seeds, and average beak depth decreases. In dry years, small seeds are less plentiful, so survival depends on the finches being able to crack the less preferred larger seeds. Average beak depth increases during dry years. It can be inferred that the change in beak depth is an adaptive response to the relative availability of small seeds from year to year.
Natural selection is situational.
What works in one environmental context may not work in another. Beak evolution on Daphne Major does not result from inheritance of acquired characteristics. The environment did not create beaks specialized for large or small seeds, but only acted on inherited variations already present in the population. There are hundreds of examples of natural selection in laboratory populations of such organisms as Drosophila. Recent discoveries, including those from molecular biology, lend support to his evolutionary view of life.