Which barrier occurs after fertilization and reduces viability or fertility of offspring?

Which barrier occurs after fertilization and reduces viability or fertility of offspring?

• A. Prezygotic Barrier
• B. Intersexual Selection
• C. Postzygotic Barrier
• D. Intrasexual Selection

Answer: (C)

Postzygotic barriers occur after fertilization and affect the offspring themselves, reducing their viability or fertility. Even when a zygote forms, genetic incompatibilities or chromosomal mismatches can lead to hybrid inviability (the hybrid dies before or soon after birth) or hybrid sterility (the hybrid is healthy but cannot produce offspring). This is why such barriers limit gene flow between species even when mating occurs and fertilization happens. In contrast, barriers that prevent fertilization in the first place are prezygotic, stopping mating from producing a zygote. Traits or processes involved in mate choice and competition, like intersexual or intrasexual selection, influence who mates but aren’t about the viability or fertility of offspring once fertilization has occurred.

Postzygotic barriers occur after fertilization and affect the offspring themselves, reducing their viability or fertility. Even when a zygote forms, genetic incompatibilities or chromosomal mismatches can lead to hybrid inviability (the hybrid dies before or soon after birth) or hybrid sterility (the hybrid is healthy but cannot produce offspring). This is why such barriers limit gene flow between species even when mating occurs and fertilization happens.

In contrast, barriers that prevent fertilization in the first place are prezygotic, stopping mating from producing a zygote. Traits or processes involved in mate choice and competition, like intersexual or intrasexual selection, influence who mates but aren’t about the viability or fertility of offspring once fertilization has occurred.