Hypothesis: If the type of food available changes, then the frequency of different types of bird beaks will change, because birds with beaks that are better adapted to the available food source will have a higher chance of survival and reproduction. Over time, this will lead to an increase in the frequency of bird beaks that are better suited to the new food source, and a decrease in the frequency of bird beaks that are less suited to the new food source. This process is known as natural selection, and it is a mechanism by which the traits of a population can change over time in response to changes in their environment.