Which concept explains that hybrids are viable and fertile, but their offspring are feeble or sterile?

Which concept explains that hybrids are viable and fertile, but their offspring are feeble or sterile?

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

Answer: (C)

Hybrid breakdown is a form of postzygotic isolation. Here, the first-generation hybrids are viable and fertile, but their offspring—the next generation or backcrosses—are feeble or sterile. This happens because genetic incompatibilities accumulate between the two parent lineages, and when their genes are combined again in the subsequent generation, incompatible interactions reduce fitness. So the described pattern—hybrids themselves doing fine, yet their offspring failing—accurately fits hybrid breakdown. Reduced hybrid viability would mean hybrids themselves don’t survive, reduced hybrid fertility means hybrids themselves are sterile, and phylogeny concerns evolutionary relationships rather than this generational pattern.

Hybrid breakdown is a form of postzygotic isolation. Here, the first-generation hybrids are viable and fertile, but their offspring—the next generation or backcrosses—are feeble or sterile. This happens because genetic incompatibilities accumulate between the two parent lineages, and when their genes are combined again in the subsequent generation, incompatible interactions reduce fitness. So the described pattern—hybrids themselves doing fine, yet their offspring failing—accurately fits hybrid breakdown. Reduced hybrid viability would mean hybrids themselves don’t survive, reduced hybrid fertility means hybrids themselves are sterile, and phylogeny concerns evolutionary relationships rather than this generational pattern.