Simplify the following text for a Grade 10 native English-speaking person.
Original: Reinforcement is required for both parapatric and sympatric speciation . Without reinforcement , the geographic area of contact between different forms of the same species , called their `` hybrid zone , '' will not develop into a boundary between the different species .
Simplified: Reinforcement is required for separation when there is a `` hybrid zone '' between two forms of a species .