Principle #1: Genetic Variation In the crocodile population the crocodile produces up to 80 eggs, however not many survive. Luckily the mother will be near her eggs to protect them while the eggs are underground.
Principle #2: Overproduction & Struggle for Survival: If the mother is not protecting her eggs then other predators like raccoons, lizards, etc will eat the crocodile eggs. If the mother crocodile comes back quickly then the eggs will be safe. This is why only a few of them can survive.
Principle #3: Differential Survival and Reproduction: When the mother isn't there at all lots of predators will be around the nest and eating the eggs. It is important that the more that are hatched and survive, they will be able to produce offspring. However the disadvantage is when there are less eggs hatching, because a small amount may not be able to survive and produce offspring.
Principle #4: Change in the Gene Pool: Surviving is beneficial. There is an advantage if there are more eggs hatching, however the disadvantage is when there are less eggs hatching.