An example of a trophic cascade is when Zebra mussels are brought into the Great Lakes,
where there is no natural predator, so the native
species numbers dwindle because the Zebra
mussels have no natural predators.
Wolves are taken out of Yellowstone and as a result,
deer numbers increase, tree nunbers decrease, and
river banks erode, causing the rivers to change
course.
There is not enough food for black bears to eat, so
they get into garbage and get sick.

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.