Hybird Vigor Explained

In order to be a hybrid, an animal must be the product of two different species: donkey and a horse, offspring is a mule; lion (m) and a tiger (f), offspring is a liger; tiger (m) and lion (f), offspring is a tigon; wolf and domestic dog, offspring is called a wolf hybrid. Remember high school Biology, animal classification: Kingdom, Phylum, Class, Order, Family, Genus, and Species?

Each animal in the crosses mentioned share the same Family (Equus, Felis, Canis) but are different species. The offspring are hybrids. Domestic dogs are the same species familiaris. When you cross breed domestic dogs (Canis familiaris ), you are within the same species; therefore, not creating a hybrid.

Hybrids are not problem free. In Ligers, no fertile male has ever been found and necropsies have proven sterility in them. Other issues in ligers and tigons: ligers may be prone to gigantism and tigons may be prone to dwarfism. Both hybridizations have shown an increase in cancer rates and decrease in lifespan. (Tiger Territory, M. Annabell, 2001). In wolf/dog hybrids, there are often behavioral issues. The domestic dog differs greatly in behavior from a wolf. Dogs were bred to be cooperative with humans while wolves fear humans and try to avoid us.

Even domestic Wolves are far different from dog in terms of behavior. Dogs often accept leadership happily while adult wolves will fight for leadership within the pack. The wolf/dog hybrid can be a time bomb temperamentally when they hit full maturity. Wolves also differ from dogs in other ways including: skull structure, nutritional needs, estrus cycles, etc. (Canine Hybrid Issues Surrounding the Wolf Dog , M. Sloan, J. Moore Porter, 2001)

Returning to the domestic dog: Canis familiaris. A breed is not a separate species, it is just a set of genes specifically bred to exhibit certain traits like the coat an Old English Sheepdog has or the build of a Rottweiler. With C. Familiaris, we just took traits in dogs of the same species and developed them to various breeds.

An example that may clarify this: all humans are Homo sapiens regardless of color, eye shape, etc. Nature helped develop certain traits to best suit the environment the H. sapiens were developing in. All domestic dogs are C. Familiaris; we just developed them into different breeds. Species is the same but there are differences based on need.

What determines a breed in the loosest sense is that when bred to another of the same breed, you will end up with the same traits. When you breed a German Shepherd Dog to another German Shepherd Dog, you only get German Shepherd Dogs.