Two different populations of finches?

Question

Consider two populations of finches, one with large beaks and one with small beaks, each living on separate islands with little precipitation (what type of seed do you expect to be most abundant?). Develop a hypothesis that predicts both how beak size will change over time in each population and how population size will change over time in each population for these finches. (Remember, a hypothesis is an "educated guess" about what you expect to happen in your experiment.) What hypothesis will you be testing? Explain your reasoning for this hypothesis.

Answer 1

Well... Birds that eat little seeds have evolved little beaks to be efficient at eating little seeds and birds that eat big seeds have evolved bigger beaks to be efficient at eating big seeds.

So we can guess that over time on the island with little seeds, the population of finches that were able to obtain the little seeds the best were the ones that survived to reproductive age.  By definition, these birds were the most "fit" and  hence these ones passed their (smaller beak) genes on to the next generation, while the ones who couldn't obtain the seeds moved on to another island, or didn't survive.  This happened for generations until beaks evolved to be just the right size to obtain little seeds.  We can guess that the same thing happened on the island with the big seeds, which resulted in finches with bigger beaks.