How would a biologist explain the variation in the beak sizes of these three species of finches? question 5 options: the beak sizes slowly changed over numerous generations with some growing larger and some growing smaller. the various habitats of the islands induced desirable genetic changes producing the variation seen today. they developed differences in beak size because of their need to be able to match the size of their beaks with the different types of food on these islands. variation in beak sizes occurred by chance and when a match between beak size and available food occurred, those birds produce more offspring. save