Which concept describes a pattern in which the first generation of hybrids is viable and fertile, but their offspring are feeble or sterile?

Which concept describes a pattern in which the first generation of hybrids is viable and fertile, but their offspring are feeble or sterile?

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

Answer: (C)

Hybrid breakdown is a form of postzygotic reproductive isolation where the first generation of offspring from two species is viable and fertile, but when these hybrids mate or their offspring backcross, the next generation shows reduced fitness—often becoming feeble or sterile. This happens because gene combinations from the two species that work okay in the F1 can disrupt development or fertility in later generations when recombination brings together new interactions. It illustrates how genetic incompatibilities can accumulate and only reveal themselves after the first hybrid generation. Other patterns don’t fit this scenario as neatly. Reduced hybrid fertility means the hybrids themselves are sterile, not their descendants. Reduced hybrid viability means the hybrids don’t survive well or at all, rather than producing later generations with problems. Phylogeny is about evolutionary relationships, not a pattern of hybrid fitness across generations.

Hybrid breakdown is a form of postzygotic reproductive isolation where the first generation of offspring from two species is viable and fertile, but when these hybrids mate or their offspring backcross, the next generation shows reduced fitness—often becoming feeble or sterile. This happens because gene combinations from the two species that work okay in the F1 can disrupt development or fertility in later generations when recombination brings together new interactions. It illustrates how genetic incompatibilities can accumulate and only reveal themselves after the first hybrid generation.

Other patterns don’t fit this scenario as neatly. Reduced hybrid fertility means the hybrids themselves are sterile, not their descendants. Reduced hybrid viability means the hybrids don’t survive well or at all, rather than producing later generations with problems. Phylogeny is about evolutionary relationships, not a pattern of hybrid fitness across generations.