Linebreeding

Linebreeding is a deliberate breeding practice in which individuals are mated to concentrate the genetic influence of a particular ancestor or lineage within a population. It is a milder form of inbreeding designed to preserve desirable traits associated with a known progenitor while avoiding the higher risk of close consanguinity that characterizes first- or second-degree matings.

In practice, linebreeding involves selecting matings where the common ancestor appears multiple times in the pedigree, but not necessarily in every generation, creating a relationship to the ancestor that is stronger than the average population but looser than direct parent-offspring or full-sibling mating.

Applications exist in animal breeding (dogs, horses, cattle, poultry) and in plant breeding, where breeders seek to stabilize features such as conformation, temperament, or yield.

Benefits include increased predictability of inherited traits, preservation of valuable lineages, and maintenance of desirable characteristics across generations. It can also help concentrate performance traits without excessive loss of genetic diversity if managed carefully.

Risks include accumulation of deleterious recessive alleles, reduced genetic variability, inbreeding depression, and potential health or fertility issues if linebreeding is carried too intensively.

Assessment is through pedigree analysis and metrics such as the inbreeding coefficient F and coancestry; linebreeding strength is described by the linebreeding coefficient relative to the common ancestor.

Ethical and welfare considerations apply, and breeders often combine linebreeding with occasional outcrossing to restore diversity.