Hybrid

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This article is about a biological term. See hybrid (disambiguation) for other meanings.

In biology, hybrid has three meanings. The first meaning is of crosses between two animals of different taxa. Hybrids between different species within the same genus are sometimes known as interspecific hybrids or crosses. Hybrids between different sub-species within a species are known as intra-specific hybrids. Hybrids between different genera are sometimes known as intergeneric hybrids.

The second meaning of "hybrid" is crosses between populations, breeds or cultivars of a single species. This second meaning is often used in plant and animal breeding.

The third meaning is in molecular biology, see Hybridization (molecular biology).

Ernst Mayr wrote of Gregor Mendel:

"He was uncertain about the nature of the kinds of peas he crossed, and, like most plant breeders, he called heterozygotes "hybrids". When he tried to confirm the laws he had found by using "other hybrids" that were actually real species hybrids, he failed. The use of the same term "hybrid" for two entirely different biological phenomena thwarted his later efforts." (This is Biology, 1997, p58f).

Some dog hybrids (used in sense two, above), are becoming increasingly popular and are being bred selectively. In cats, the erroneous term feral-domestic hybrid is often used to indicate a cross between the domestic cat and a wild cat species (erroneous because a "feral" animal is a domestic animal that has reverted to the wild state).

An example of an intra-specific hybrid is a hybrid between a Bengal tiger and an Amur (Siberian) Tiger.

Plant hybrids, especially, are often stronger than either parent variety, a phenomenon which when present is known as hybrid vigour (heterosis) or heterozygote advantage. Plant breeders make use of a number of techniques to produce hybrids.

The lonicera fly is the first known animal species that resulted from natural hybridization. Until the discovery of the lonicera, this process was known to occur in nature only among plants.

Contents 1 Interspecific hybrids 2 Hybrid plants 3 Hybrids in nature 4 Mythological and legendary hybrids 5 Etymology 6 See also

Interspecific hybrids

Interspecific hybrids are bred by mating two species, normally from within the same genus. The offspring display traits and characteristics of both parents. The offspring of an interspecific cross may be sterile. Sterility is often attributed to the different number of chromosomes the two species have, for example donkeys have 62 chromosomes, while horses have 64, mules and hinnies have 63. Mules, hinnies, and other normally sterile interspecific hybrids normally cannot produce viable gametes because the extra chromosome cannot make a homologous pair at meiosis, meiosis is disrupted, and viable sperm and eggs are not formed. However, fertility in both female mules and hinnies has been reported with a donkey as the father.[1]

While it is possible to predict the genetic composition of a backcross on average, it is not possible to accurately predict the composition of a particular backcrossed individual, due to random segregation of chromosomes. In a species with two pairs of chromosomes, a twice backcrossed individual would be predicted to contain 12.5% of one species' genome (say, species A). However, it may, in fact, still be a 50% hybrid if the chromosomes from species A were lucky in two successive segregations, and meiotic crossovers happened near the telomeres. The chance of this is fairly high, 1/2^(2*2)=1/16 (where the "two times two" comes about from two rounds of meiosis with two chromosomes); however, this probability declines markedly with chromosome number and so the actual composition of a hybrid will be increasingly closer to the predicted composition.

Hybrids are often named by the portmanteau method, combining the names of the two parent species. For example, a zeedonk is a cross between a zebra and a donkey. Since the traits of hybrid offspring often vary depending on which species was mother and which was father, it is traditional to use the father's species as the first half of the portmanteau. For example, a liger is a cross between a male lion and a female tiger, while a tigon is a cross between a male tiger and a female lion.

Some animal interspecies hybrids are:

• Mule, a cross of female horse and a male donkey.
• Hinny, a cross between a female donkey and a male horse.Image:Zeedonk 800.jpg
• Zeedonk or zonkey, a zebra/donkey cross.
• Zorse or zebroid, a zebra/horse cross
• Zony/zetland, a zebra/pony cross ("zony" is a generic term; "zetland" is specifically a hybrid of the Shetland pony breed with a zebra)
• Dzo, zo or yakow: a cross between a domestic cow/bull and a yak. See also Bovid hybrids.
• Beefalo/cattalo, a cross of an American Bison and a domestic cow. This is a fertile breed, although the two species are in different genera (Bison and Bos, respectively). See also Bovid hybrids.
• Zubron, a hybrid between Wisent (European Bison) and domestic cow.
• Sheep-goat hybrids, such as the Toast of Botswana.
• Ursinae hybrids occur between black bears, brown bears, Kodiak and polar bears.
• Wolfdog, the cross between a domestic dog and a Wolf; in former times this often resulted unintendedly from a domestic dog bitch straying when in oestrus and being mated by a wolf. Fertile Canid hybrids occur between coyotes, wolves, dingos, jackals and domestic dogs. Dogs and wolves may be considered the same species, making wolfdogs a non-hybrid.
• Hybrids between spotted owls and barred owls
• Ligers and Tigons (crosses between a Lion and a Tiger) and other panthera hybrids. Various other wild cat crosses are known involving the Lynx, Bobcat, Leopard, Serval, etc.
• Bengal cat, a cross between the Asian Leopard cat and the domestic cat, one of many hybrids between the domestic cat and wild cat species. The domestic cat, African wild cat and European wildcat may be considered variant populations of the same species (Felis silvestris), making such crosses non-hybrids.
• Congolese Spotted Lion
• Cama, a cross between a Camel and a Llama, also an intergeneric hybrid.
• Wolphin, a fertile but very rare cross between a False Killer Whale and a Bottlenose Dolphin.
• A fertile cross between an albino King Snake and an albino Corn Snake.
• At Chester Zoo in England, a cross between African elephant (male) and Indian elephant (female). The male calf was named Motty. It died of gut infection after twelve days.
• Cagebird breeders sometimes make hybrids between species of finch, such as goldfinch x canary.

Hybrids should not be confused with chimaeras such as the chimera between sheep and goat known as the geep.

Links to more hybrid animals, or more specific details:

• Information about Ligers
• Amazing Animals
• Hybrid Mammals
• Hybrids of wildcats with domestic cats
• Bird Hybrids Database - Search by name of bird

Hybrid plants

Plant species hybridize a lot more readily than animal species and they are generally fertile. Plant hybrids are often created to get different characteristics from both parents and to improve production of seeds or fruit such as to make a plant hardier or more disease resistant. Hybrid plants are plants that are created manually, so they can have characteristics that are helpful.

Some plant hybrids include:

• Leyland Cypress, a hybrid between Monterey Cypress and Nootka Cypress.
• Loganberry, a hybrid between raspberry and blackberry.
• London Plane, a hybrid between Oriental Plane and American Plane (American Sycamore).
• Tangelo, a hybrid of a mandarin orange and a pomelo or a grapefruit which may have been developed in Asia about 3,500 years ago.
• limequat, lime and kumquat hybrid
• Triticale, a wheat-rye hybrid.
• Wheat, Most modern and ancient wheat breeds are themselves hybrids.

Hybrids in nature

Template:Section-stub Hybridisation between two closely related species is actually a common occurrence in nature. Many hybrid zones are known where the ranges of two species meet, and hybrids are continually produced in great numbers. These hybrid zones are useful as biological model systems for studying the mechanisms of speciation.

Mythological and legendary hybrids

In ancient and modern local folktales, there exist hybrids resulting from the union between a human parent and an animal or a non-human sentient being. Some of these hybrids are crosses with humans and: brownies, nymphs, gods, Moo-Moo (Solomon Island Giant), chimpanzees (Humanzee), aliens, bats (Batboy), snakes/lizards (Naga, Syrictae), dropa, giants, cat people, mermaids, fairies, watchers, demons, dryads, spirits, incubus, succubus, pech, triton, larvae, martes, and others. One example is the Minotaur.

Etymology

The word came from Ancient Greek hybridēs, literally meaning "son of outrageous conduct", and used to mean "hybrid between sheep and goat".

See also

• Artificial selection
• Bird hybrids
• Chimera (genetics)
• Chimera (mythology)
• Dog hybrids and crossbreeds
• Felid hybrids
• Genetic Engineering
• Hybrid names (botany)
• Hybrid vehicle
• Hybrid zone
• Selective breeding
• Sheep-goat hybrids

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