What is hybrid breakdown?

Hybrid breakdown refers to a situation in which the first generation of hybrid offspring, generated from two different species or strains, is viable and fertile. However, in subsequent generations, these hybrids may experience reduced fitness or viability, leading to negative phenotypic effects or even sterility. The correct answer highlights that while the initial hybrids may appear healthy and capable of reproduction, their descendants often face significant challenges that limit their survival and reproductive success.

In many cases, these issues arise due to genetic incompatibilities that manifest only after the first generation, often as a result of the interaction between the parental genome's alleles and those of the hybrids. This phenomenon is particularly noteworthy in plants, where hybrid breakdown can lead to plants that are unable to thrive in their environment, exhibit abnormal traits, or have reduced offspring viability.

Understanding hybrid breakdown is important in the study of speciation and genetics, as it provides insight into the complexities of hybridization and the long-term viability of hybrid populations.