Final answer:
Gametic isolation is a method of protecting the genetic isolation of a population by preventing the fertilization of eggs by sperm from a different species.
Step-by-step explanation:
The method of protecting the genetic isolation of a population where the inability of sperm to fertilize eggs of a different species is called gametic isolation.
Gametic isolation is a type of prezygotic barrier that prevents fertilization from taking place due to differences in the gamete cells of different species. When the sperm and egg are incompatible, they cannot fuse and form a zygote. This is a reproductive mechanism that contributes to the preservation of species and the maintenance of genetic isolation.
For example, damselfly males and females of different species have differently shaped reproductive organs. If one species tries to mate with another, their body parts simply do not fit together, leading to gametic isolation.