Final answer:
Fertilization in animals occurs internally or externally, with internal offering protection and specificity but resulting in fewer offspring, while external increases genetic variation but has lower individual survival rates.
Step-by-step explanation:
The process of fertilization in animals can occur either internally or externally, each having its own set of advantages and disadvantages.
Internal fertilization offers the advantage of protecting the fertilized egg from dehydration, especially on land. This method isolates the embryo within the female's body, reducing the chances of predation on the young. It also facilitates the fertilization of eggs by a specific male, increasing the probability of successful reproduction with a chosen partner. However, internal fertilization typically results in the production of fewer offspring, though these have higher survival rates.
In contrast, external fertilization is often seen in aquatic environments where it prevents the eggs from drying out. This method, such as broadcast spawning, can result in greater genetic variation within a population. However, the failure to isolate the young from predators means a significantly larger number of eggs must be produced to ensure the survival of the species. While the survival rate of each individual egg or larva is low, the rapid maturation of those that do survive can offset this disadvantage.