Hybrid Vigor, (HETEROSIS)~What is it? “Heterosis is a term used in genetics and selective breeding. In the world of dog breeding, no one person or organization owns a particular dog breed, we are only the custodian, and have an obligation to create the healthiest creatures possible. Crossbreeding pure and hybrid dogs, as long as it is done with care and betters the animal, regarding health and temperament is an important part of micro-evolution. That said, we do have respect for pure breeds and their fanciers, and do not condone crossbreeding, without expressed written permission of the purebred breeder who has sold the pure bred dog for breeding purposes. We are only the caretakers of dogs, and must do all in our power to breed healthy dogs that have a purpose and work to enhance the lives of our fellow human beings.

In nature, not only will individual animals often travel great distances to find unoccupied territories, they may also cross the species barrier as they do so. A wolf will mate with both a dog and a coyote, while finches leap across the species barrier at the drop of a hat. A spotted owl will freely mate with a barred owl, while most amazon parrots freely cross breed. A lion can mate with a tiger and produce fertile offspring, and an African elephant can cross breed with an Asian elephant. A muskellunge will cross with a northern pike, and a sunfish will cross with a bluegill. Trout, and salmon species readily hybridize with their own. Many species of hawks and falcons will also cross the species line, while a buffalo will cross with a cow. A hunter in Alaska once shot an animal that turned out to be a cross between a polar bear and a grizzly. The point here is not that trans-species out-crosses are common, but that even between distinct species, nature often runs its train “loose on the tracks,” and a considerable amount of genetic wobble is allowed. Nature allows out-crosses because it values heterogeneous genes, while it punishes homogeneous genes by “culling” animals through a process of dwindling survivorship (neonatal mortality), shortened lifespans, and infecundity. The term heterosis, also known as hybrid vigor or out breeding enhancement, describes the increased strength of different characteristics in hybrids the possibility to obtain a genetically superior individual by combining the virtues of its parents. Heterosis is the opposite of inbreeding depression, which occurs with increasing homozygosity. The term often causes controversy, particularly in terms of the selective breeding of domestic animals, because it is sometimes believed that all crossbred plants or animals are genetically superior to their parents this is true only in certain circumstances: when a hybrid is seen to be superior to its parents, this is known as hybrid vigor. When the opposite happens, and a hybrid inherits traits from their parents that makes them unfit for survival, the result is referred to as outbreeding depression.

Some breeders use this term to sell you on Doodles, regarding one health concern hybrid vigor is a positive step specific to mixed breed dogs, beware it may only affects one concern. When pure bred dogs are bred the lines are crossed over and over, possible negative genetic traits are reintroduced again and again. If line or inbreeding is practiced possible negative genetic traits are reintroduced at even higher rates. Typically for a disease like Addison’s disease to be expressed in a dog it requires the genetic trait to be passed by both parents. If it is only passed by one parent the trait is recessive and the dog never shows any signs or symptoms of the disease in its lifetime. Therefore, if a breed like the Poodle has been known to carry SA (a skin condition) and a breed like Labrador is known not to carry SA, then the first generation breeding of these dogs cannot express SA. This is a positive health affect of hybrid vigor. Once a Labradoodle is bred to another Labradoodle or another Poodle in this specific case of SA, the hybrid vigor influence is diluted. The primary reason to advocate for hybrid vigor is temperament. For generations pure bred dogs have been inbreed and line breed to reduce size or create the perfect conformation standard. Or another dog was selected as a breeding dog specifically due to its size of conformation, its ability to produce smaller offspring or win in the show ring over temperament was the concern. This has lead to poor temperament offspring in general. The crossing out to unrelated lines, if selecting breeding dogs with temperament as top criteria, begets top temperament puppies. Yeah for hybrid vigor. On the flip side, if both breeds carry a disease hybrid vigor has absolutely no affect. This is why health testing breeding dogs is so critical. Health testing breeding dogs costs about $1000 to $1500 per dog, but is NECESSARY for a breeder to know what they are producing and to support a positive step in reducing health incidents in Labradoodles, Australian Labradoodles, and Australian Cobberdogs, and Cobberdogs. Diseases that are of concern to Poodles, Labs and all other breeds used in Australian Labradoodles/Cobberdogs are Hip Dysplasia, Elbow Dysplasia, Heart conditions, Eye conditions, and Thyroid Conditions. All breeders should be testing their breeding dogs by completing Hip and Elbow testing (either OFA, PennHIP or BVA test), Heart Screening, Eye testing (CERF or other), before breeding, and making strategic, intelligent breeding decisions, with the results of the genetic tests. Many inherited traits can now be screened for using simple DNA tests.