Within the population of finches on the galapagos islands, exists within beak size. during wet years, small tender seeds flourish and beaks have a selective advantage.

I would say that the answers are: 'large variation' and 'smaller'. A population of finches with a large variation in genotype, and therefore phenotype, for beak size would allow the population to adapt to changing food availability. The increase in small seeds within their environment would provide a selective advantage to individuals with smaller beaks, as they would be more deft at handling the seeds.