Both pre- and post-zygotic barriers to reproduction serve to prevent closely-related species from producing fertile offspring.

Question

Both pre- and post-zygotic barriers to reproduction serve to prevent closely-related species from producing fertile offspring.

Answer 1

Prezygotic barriors are things that prevents two animals from mating BEFORE fertilization and even before they have chance to mate. So that could mean that their gametes (sex cells) are incompatible Ex: A cat and a tiger while they share distant relatives their sex cells are incompatitble. Another is that both species can not come in contact due to isolated habitats and different habits. This could mean different mating behaviors (Behavioral Isolation) and times (Temporal Isoloation) they like to be active.

Post-Zygotic Isolation is things preventing viable fertile offspring AFTER mating. Lions and Tigers can have offspring with trial and error. That offspring though could be sterile (they can't have their own offspring) or They are unable to live to a age where they can reproduce.