Which term is used to describe the situation where the first generation of hybrids is viable, but subsequent generations fail to maintain the lineage?

Which term is used to describe the situation where the first generation of hybrids is viable, but subsequent generations fail to maintain the lineage?

• A. Hybrid Breakdown
• B. Reduced Hybrid Viability
• C. Phylogeny
• D. Reduced Hybrid Fertility

Answer: (A)

This question focuses on how hybrid fitness can change across generations. Hybrid breakdown is the pattern where the first generation of hybrids is viable (and may be fertile), but when those hybrids produce the next generation, their offspring have reduced viability or fertility, causing the lineage to fail to persist. This happens because gene combinations from the two species can interact in incompatible ways in later generations. In the initial cross, you might get workable offspring, but as genes assort and pair differently in F2 or backcross generations, harmful interactions surface that reduce survival or reproduction. The other terms describe different scenarios: reduced hybrid viability means hybrids fail to develop or survive in the first generation; reduced hybrid fertility means hybrids are sterile; and phylogeny is about the evolutionary relationships among species, not about how hybrid fitness changes across generations.

This question focuses on how hybrid fitness can change across generations. Hybrid breakdown is the pattern where the first generation of hybrids is viable (and may be fertile), but when those hybrids produce the next generation, their offspring have reduced viability or fertility, causing the lineage to fail to persist.

This happens because gene combinations from the two species can interact in incompatible ways in later generations. In the initial cross, you might get workable offspring, but as genes assort and pair differently in F2 or backcross generations, harmful interactions surface that reduce survival or reproduction.

The other terms describe different scenarios: reduced hybrid viability means hybrids fail to develop or survive in the first generation; reduced hybrid fertility means hybrids are sterile; and phylogeny is about the evolutionary relationships among species, not about how hybrid fitness changes across generations.