What term denotes the reduced fertility of hybrid individuals themselves, not the next generation?

What term denotes the reduced fertility of hybrid individuals themselves, not the next generation?

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

Answer: (B)

The main idea is postzygotic reproductive isolation—the barriers that act after fertilization to prevent gene flow between species. Reduced hybrid fertility means the hybrids themselves have lower fertility or are sterile, so they cannot produce offspring. This directly stops the exchange of genes between the parent species even though the hybrids might survive to adulthood. An everyday example is a mule (horse × donkey), which is typically sterile due to differences in chromosome number that hinder proper meiosis. This is different from reduced hybrid viability, where hybrids fail to survive to reproductive age, and from hybrid breakdown, where later generations have reduced fitness. Phylogeny, meanwhile, is about evolutionary relationships, not the fertility of hybrids.

The main idea is postzygotic reproductive isolation—the barriers that act after fertilization to prevent gene flow between species. Reduced hybrid fertility means the hybrids themselves have lower fertility or are sterile, so they cannot produce offspring. This directly stops the exchange of genes between the parent species even though the hybrids might survive to adulthood. An everyday example is a mule (horse × donkey), which is typically sterile due to differences in chromosome number that hinder proper meiosis. This is different from reduced hybrid viability, where hybrids fail to survive to reproductive age, and from hybrid breakdown, where later generations have reduced fitness. Phylogeny, meanwhile, is about evolutionary relationships, not the fertility of hybrids.