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This article is about a biological term. For other uses, see Hybrid.

In biology, hybrid has two meanings. Foundations of modern biology There are five unifying principles [1] The first meaning is the result of interbreeding between two animals or plants of different taxa. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to 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. Extremely rare interfamilial hybrids have been known to occur (such as the guineafowl hybrids). The guineafowl (sometimes called guineahen are a family of birds in the same order as the Pheasants turkeys and other game birds and is native to The second type of hybrid consists of crosses between populations, breeds or cultivars within a single species. See Breed (song for the song by Nirvana. See Breed (video game for the video game by Brat Designs A cultivar is a cultivated Plant that has been selected and given a unique name because of its decorative or useful characteristics it is usually distinct from similar This second meaning is often used in plant and animal breeding. In plant and animal breeding, hybrids are commonly produced and selected because they have desirable characteristics not found or inconsistently present in the parent individuals or populations. This rearranging of the genetic material between populations or races is often called hybridization.

Contents

Types of hybrids

Depending on the parents, there are a number of different types of hybrids;[2]

Single cross hybrids - result from the cross between two pure bred lines and produces an F1 generation called an F1 hybrid (F1 is short for Filial 1, meaning "first offspring). A true breeding organism, sometimes also called a pure-bred is an Organism having certain biological traits which are passed on to all subsequent generations F1 hybrid is a term used in Genetics and Selective breeding. F1 stands for Filial 1, the first filial Generation seeds/plants or animal The cross between two different homozygous lines produces an F1 hybrid that is heterozygous; having two alleles, one contributed by each parent and typically one is dominant and the other recessive. Zygosity refers to the genetic condition of a Zygote. In genetics zygosity describes the similarity or dissimilarity of DNA between Homologous Zygosity refers to the genetic condition of a Zygote. In genetics zygosity describes the similarity or dissimilarity of DNA between Homologous The F1 generation is also homogeneous, producing offspring that are all similar to each other.

Double cross hybrids - result from the cross between two different F1 hybrids. [3]

Three-way cross hybrids - result from the cross between one parent that is an F1 hybrid and the other is from an inbred line. [4]

Triple cross hybrids - result from the crossing of two different three-way cross hybrids.

Population hybrids - result from the crossing of plants or animals in a population with another population. In Biology a population is the collection of inter-breeding organisms of a particular Species; in Sociology These include crosses between organisms such as interspecific hybrids or crosses between difference races.

Interspecific hybrids

Interspecific hybrids are bred by mating two species, normally from within the same genus. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic The offspring display traits and characteristics of both parents. The offspring of an interspecific cross very often are sterile; thus, hybrid sterility prevents the movement of genes from one species to the other, keeping both species distinct. [5] Sterility is often attributed to the different number of chromosomes the two species have, for example donkeys have 62 chromosomes, while horses have 64 chromosomes, and mules and hinnies have 63 chromosomes. The donkey or ass, Equus asinus, is a member of the Equidae or horse family and an odd-toed ungulate. A chromosome is an organized structure of DNA and Protein that is found in cells. The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. In its common modern meaning a mule is the offspring of a male Donkey and a female Horse, which is classified as a kind of F1 hybrid. The word "hinny" is also a term of endearment used in North East England, equivalent to "honey" see Geordie. Mules, hinnies, and other normally sterile interspecific hybrids 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. A gamete (from Ancient Greek γαμέτης; translated gamete = wife gametes = husband is a cell that fuses with another gamete In Biology or life science meiosis (pronounced my-oh-sis is a process of reductional division in which the number of chromosomes per cell is cut in half However, fertility in female mules has been reported with a donkey as the father. [6] Most often other mechanisms are used by plants and animals to keep gametic isolation and species distinction. Species often have different mating or courtship patterns or behaviors, the breeding seasons may be distinct and even if mating does occur antigenic reactions to the sperm of other species prevent fertilization or embryo development. The Lonicera fly is the first known animal species that resulted from natural hybridization. The Lonicera fly, a hybrid in the genus Rhagoletis, is a North American fruit fly of the family Tephritidae. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Until the discovery of the Lonicera fly, this process was known to occur in nature only among plants. Plants are living Organisms belonging to the kingdom Plantae.

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. A telomere is a region of repetitive DNA at the end of Chromosomes which protects the end of the chromosome from destruction 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. A zonkey (also known as zebrass zebronkeyzeasses zeedonk zedonk zebadonk zenkey donbra zebrinny or deebra) is a cross between a Zebra and Zebras are African Equids best known for their distinctive white and black stripes The donkey or ass, Equus asinus, is a member of the Equidae or horse family and an odd-toed ungulate. 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. The liger, is a hybrid cross between a male Lion and a female Tiger (i The lion ( Panthera leo) is a member of the family Felidae and one of four Big cats in the Genus Panthera. The tiger ( Panthera tigris) is a member of the Felidae family the largest and the most powerful of the four " Big cats quot in the Genus A tigon or tigron is a hybrid cross between a male Tiger and a female Lion.

Examples of hybrid animals

A "Zeedonk", a zebra/donkey hybrid
A "Zeedonk", a zebra/donkey hybrid
A "Liger", a Lion/Tiger hybrid
A "Liger", a Lion/Tiger hybrid
A "Jaglion", a Jaguar/Lion hybrid
A "Jaglion", a Jaguar/Lion hybrid
Würdemann's Heron, a great blue/white heron hybrid
Würdemann's Heron, a great blue/white heron hybrid

Hybrids should not be confused with chimaeras such as the chimera between sheep and goat known as the geep. The Blood parrot (also known as bloody parrot and blood parrotfish; no Binomial nomenclature) is a hybrid Cichlid. The la severum, la Heros severus (previously known as Cichlasoma severum) is a freshwater tropical Cichlid native to the Amazon In Zoology, a chimera is an animal that has two or more different populations of genetically distinct cells that originated in different Zygotes if the The domestic goat ( Capra aegagrus hircus) is a subspecies of goat Domesticated from the Wild goat of Southwest Asia and Eastern Europe Geep can also refer to a series of railroad locomotives A sheep-goat chimera (sometimes called a geep in popular media is a chimera Wider interspecific hybrids can be made via in vitro fertilization or somatic hybridization, however the resulting cells are not able to develop into a full organism. In vitro fertilisation ( IVF) is a process by which An example of interspecific hybrid cell lines is the humster (hamster x human) cells. A Humster is a hybrid cell line made from hamster Oocyte fertilized with human sperm routinely created for mainly two reasons To avoid legal issues with

Hybrid plants

Plant species hybridize more readily than animal species, and the resulting hybrids are more often fertile hybrids and may reproduce, though there still exist sterile hybrids and selective hybrid elimination where the offspring are less able to survive and are thus eliminated before they can reproduce. A number of plant species are the result of hybridization and polyploidy with many plant species easily cross pollinating and producing viable seeds, the distinction between each species is often maintained by geographical isolation or differences in the flowering period. Polyploidy occurs in cells and Organisms when there are more than two homologous sets of Chromosomes. Animals, being more mobile, have developed complex mating behaviors that maintain the species boundary and when hybrids do occur, natural selection tends to weed them out of the population since these hybrids generally can not find mates that will accept them or they are less adapted and fit for survival in their habitats. Since plants hybridize frequently without much work, they are often created by humans in order to produce improved plants. These improvements can include the production of more or improved; seeds, fruits or other plant parts for consumption, or to make a plant more winter or heat hardy or improve its growth and/or appearance for use in horticulture. Much work is now being done with hybrids to produce more disease resistant plants for both agricultural and horticultural crops. In many groups of plants hybridization has been used to produce larger and more showy flowers and new flower colors.

A sterile Trillium hybrid between Trillium cernuum and Trillium grandiflorum
A sterile Trillium hybrid between Trillium cernuum and Trillium grandiflorum

Many plant genera and species have their origins in polyploidy. Trillium cernuum ( Nodding Trillium) is a species of Trillium native to northeastern North America, from Newfoundland Trillium grandiflorum, commonly known as white trillium, great white trillium, white wake-robin, or in French as trille Autopolyploidy resulting from the sudden multiplication in the number of chromosomes in typical normal populations caused by unsuccessful separation of the chromosomes during meiosis. Tetraploids or plants with four sets of chromosomes are common in a number of different groups of plants and over time these plants can differentiate into distinct species from the normal diploid line. In Oenothera lamarchiana the diploid species has 14 chromosomes, this species has spontaneously given rise to plants with 28 chromosomes that have been given the name Oenthera gigas. Tetraploids can develop into a breeding population within the diploid population and when hybrids are formed with the diploid population the resulting offspring tend to be sterile triploids, thus effectively stopping the intermixing of genes between the two groups of plants (unless the diploids, in rare cases, produce unreduced gametes) Another form of polyploidy called allopolyploidy occurs when two different species mate and produce hybrids. Usually the typical chromosome number is doubled in successful allopolyploid species, with four sets of chromosomes the genotypes can sort out to form a complete diploid set from the parent species, thus they can produce fertile offspring that can mate and reproduce with each other but can not back-cross with the parent species. Allopolyploidy in plants often gives them a condition called hybrid vigour, which results in plants that are larger and stronger growing than either of the two parent species. Allopolyploids are often more aggressive growing and can be invaders of new habitats. Sterility in a hybrid is often a result of chromosome number; if parents are of differing chromosome pair number, the offspring will have an odd number of chromosomes, leaving them unable to produce chromosomally balanced gametes. A chromosome is an organized structure of DNA and Protein that is found in cells. A chromosome is an organized structure of DNA and Protein that is found in cells. A gamete (from Ancient Greek γαμέτης; translated gamete = wife gametes = husband is a cell that fuses with another gamete [7] While this is a negative in a crop such as wheat, when growing a crop which produces no seeds would be pointless, it is an attractive attribute in some fruits. Wheat ( Triticum spp is a worldwide cultivated grass from the Levant area of the Middle East. Bananas and seedless watermelon, for instance, are intentionally bred to be triploid, so that they will produce no seeds. For the fruit see Banana. For other meanings see Banana (disambiguation. Watermelon ( Citrullus lanatus ( Thunb) Matsum & Nakai family Cucurbitaceae) refers to both Fruit and Plant of a vine-like (climber Polyploidy occurs in cells and Organisms when there are more than two homologous sets of Chromosomes. Many hybrids are created by humans, but natural hybrids occur as well. Plant hybrids, especially, are often stronger than either parent variety, a phenomenon which when present is known as hybrid vigour (heterosis) or heterozygote advantage. Heterosis is a term used in Genetics and Selective breeding. The term heterosis also known as hybrid vigor or outbreeding enhancement, [8] Plant breeders make use of a number of techniques to produce hybrids, including line breeding and the formation of complex hybrids. Plant breeding is the art and science of changing the genetics of plants for the benefit of humankind

Some plant hybrids include:

Some natural hybrids are:

Some horticultural hybrids:

Hybrids in nature

Hybridisation between two closely related species is actually a common occurrence in nature. Kindred Spirit Hybrid Oak is an Oak hybrid of ''Quercus robur fastigiata'' x ''Quercus bicolor'' thus forming a Quercus x warei Many hybrid zones are known where the ranges of two species meet, and hybrids are continually produced in great numbers. A hybrid zone exists where the ranges of two Interbreeding Species meet These hybrid zones are useful as biological model systems for studying the mechanisms of speciation (Hybrid speciation). Speciation is the Evolutionary process by which new biological Species arise Hybrid speciation is the process wherein Hybridization between two different closely related Species leads to a distinct Phenotype. Recently DNA analysis of a bear shot by a hunter in the North West Territories confirmed the existence of naturally occurring and fertile polar bear/grizzly bear hybrids. The Northwest Territories (ˌnɔrθˌwɛstˈtɛrɨtɔriz ( NWT or NT; French, les Territoires du Nord-Ouest) is a territory The polar bear ( Ursus maritimus) is a Bear native to the Arctic Ocean and its surrounding seas The Grizzly Bear (Ursus arctos horribilis, also known as the Silvertip Bear, is a Subspecies of Brown bear (Ursus arctos that lives [9] There have been reports of similar supposed hybrids, but this is the first to be confirmed by DNA analysis. In 1943, Clara Helgason described a male bear shot by hunters during her childhood. It was large and off-white with hair all over its paws. The presence of hair on the bottom of the feet suggests it was a natural hybrid of Kodiak and Polar bear.

In some species, hybridisation plays an important role in evolutionary biology. While most hybrids are disadvantaged as a result of genetic incompatibility, the fittest survive, regardless of species boundaries. The " disadvantaged " is a generic term for individuals or groups of people who Face special problems such as physical or mental disability[http//www They may have a beneficial combination of traits allowing them to exploit new habitats or to succeed in a marginal habitat where the two parent species are disadvantaged. This has been seen in experiments on sunflower species. Unlike mutation, which affects only one gene, hybridisation creates multiple variations across genes or gene combinations simultaneously. Successful hybrids could evolve into new species within 50-60 generations. This leads some scientists to speculate that life is a genetic continuum rather than a series of self-contained species.

Where there are two closely related species living in the same area, less than 1 in 1000 individuals are likely to be hybrids because animals rarely choose a mate from a different species (otherwise species boundaries would completely break down). In some closely related species there are recognized "hybrid zones".

Some species of Heliconius butterflies exhibit dramatic geographical polymorphism of their wing patterns, which act as aposematic signals advertising their unpalatability to potential predators. Where different-looking geographical races abut, inter-racial hybrids are common, healthy and fertile. Heliconius hybrids can breed with other hybrid individuals and with individuals of either parental race. These hybrid backcrosses are disadvantaged by natural selection because they lack the parental form's warning coloration, and are therefore not avoided by predators.

A similar case in mammals is hybrid White-Tail/Mule Deer. The hybrids don't inherit either parent's escape strategy. White-tail Deer dash while Mule Deer bound. The hybrids are easier prey than the parent species.

In birds, healthy Galapagos Finch hybrids are relatively common, but their beaks are intermediate in shape and less efficient feeding tools than the specialised beaks of the parental species so they lose out in the competition for food. Following a major storm in 1983, the local habitat changed so that new types of plants began to flourish, and in this changed habitat, the hybrids had an advantage over the birds with specialised beaks - demonstrating the role of hybridization in exploiting new ecological niches. If the change in environmental conditions is permanent or is radical enough that the parental species cannot survive, the hybrids become the dominant form. Otherwise, the parental species will re-establish themselves when the environmental change is reversed, and hybrids will remain in the minority.

Natural hybrids may occur when a species is introduced into a new habitat. In Britain, there is hybridisation of native European Red Deer and introduced Chinese Sika Deer. Conservationists want to protect the Red Deer, but evolution favors the Sika Deer genes. There is a similar situation with White-headed Ducks and Ruddy Ducks.

Expression of Parental Traits in Hybrids

When two distinct types of organisms breed with each other, the resulting hybrids typically have intermediate traits (e. g. , one parent has red flowers, the other has white, and the hybrid, pink flowers). [10] Commonly, hybrids also combine traits seen only separately in one parent or the other (e. g. , a bird hybrid might combine the yellow head of one parent with the orange belly of the other). [11] Most characteristics of the typical hybrid are of one of these two types, and so, in a strict sense, are not really new. However, an intermediate trait does differ from those seen in the parents (e. g. , the pink flowers of the intermediate hybrid just mentioned are not seen in either of its parents). Likewise, combined traits are new when viewed as a combination.

In a hybrid, any trait that falls outside the range of parental variation is termed heterotic. In Physics, a heterotic string is a peculiar mixture (or hybrid of the bosonic string and the Superstring (the adjective heterotic comes from Heterotic hybrids do have new traits, that is, they are not intermediate. Positive heterosis produces more robust hybrids, they might be stronger or bigger; while the term negative heterosis refers to weaker or smaller hybrids. [12] Heterosis is common in both animal and plant hybrids. For example, hybrids between a lion and a tigress ("ligers") are much larger than either of the two progenitors, while a tigon (lioness × tiger) is smaller. Also the hybrids between the Common Pheasant (Phasianus colchicus) and domestic fowl (Gallus gallus) are larger than either of their parents, as are those produced between the Common Pheasant and hen Golden Pheasant (Chrysolophus pictus). The Common Pheasant ( Phasianus colchicus) is a bird in the Pheasant family (Phasianidae The chicken ( Gallus gallus, sometimes G gallus domesticus) is a domesticated Fowl which is traditionally believed to have descended from The Golden Pheasant or " Chinese Pheasant ", ( Chrysolophus pictus) is a Gamebird of the order Galliformes (gallinaceous [13] Spurs are absent in hybrids of the former type, although present in both parents. [14]

When populations hybridize, often the first generation (F1) hybrids are very uniform. Typically, however, the individual members of subsequent hybrid generations are quite variable. High levels of variability in a natural population, then, are indicative of hybridity. Researchers use this fact to ascertain whether a population is of hybrid origin. Since such variability generally occurs only in later hybrid generations, the existence of variable hybrids is also an indication that the hybrids in question are fertile.


Genetic mixing and Extinction

Main article: Genetic pollution

Regionally developed ecotypes can be threatened with extinction when new alleles or genes are introduced that alter that ecotype. Genetic pollution is undesirable Gene flow into wild populations Within a Species, an ecotype is a genetically unique Population that is adapted to its local environment In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. An allele (ˈæliːl (UK /əˈliːl/ (US (from the Greek αλληλος allelos, meaning each other) is one member of a pair or series of different forms This is sometimes called genetic mixing. Genetic pollution is undesirable Gene flow into wild populations [15] Hybridization and introgression of new genetic material can lead to the replacement of local genotypes if the hybrids are more fit and have breeding advantages over the indigenous ecotype or species. Introgression, in Genetics (particularly plant genetics is the movement of a Gene ( Gene flow) from one species into the gene pool of another by backcrossing The genotype is the genetic constitution of a cell an organism or an individual (i Fitness (often denoted w in Population genetics models is a central concept in evolutionary theory. These hybridization events can result from the introduction of non native genotypes by humans or through habitat modification, bringing previously isolated species into contact. Genetic mixing can be especially detrimental for rare species in isolated habitats, ultimately effecting the population to such a degree than none of the originally genetically distinct population remains. [16]. [17]

Effect on biodiversity and food security

Main articles: biodiversity and food security

In agriculture and animal husbandry, the green revolution's use of conventional hybridization increased yields by breeding "high-yielding varieties". Biodiversity is the variation of Life forms within a given Ecosystem, Biome or for the entire Earth. Food security refers to the availability of food and one's access to it Animal husbandry, also called Animal science, stockbreeding or simple husbandry, is the agricultural practice of breeding The Green Revolution refers to the transformation of Agriculture that began in 1945 at the request of the Mexican government to establish an agricultural research station to High-yielding varieties (HYVs are any of a group of genetically enhanced Cultivars of crops such as Rice, Maize and Wheat that have an increased The replacement of locally indigenous breeds, compounded with unintentional cross-pollination and crossbreeding (genetic mixing), has reduced the gene pools of various wild and indigenous breeds resulting in the loss of genetic diversity. Genetic pollution is undesirable Gene flow into wild populations Genetic diversity is a level of Biodiversity that refers to the total number of genetic characteristics in the genetic makeup of a species [18] Since the indigenous breeds are often better adapted to local extremes in climate and have immunity to local pathogens this represents a significant genetic erosion of the gene pool for future breeding. Genetic erosion is a process whereby an already limited Gene pool of an Endangered species of plant or animal diminishes even more when individuals from the surviving Newer, genetically engineered (GE) varieties are a problem for local biodiversity. Some of these plants contain designer genes that would be unlikely to evolve in nature, even with conventional hybridization. Protein engineering is the application of Science, Mathematics, and Economics to the process of developing useful or valuable Proteins It is [19][20] These may pass into the wild population with unpredictable consequences and may be detrimental for the success of future breeding programs.

Limiting factors

A number of conditions exist that limit the success of hybridization, the most obvious is great genetic diversity between most species. But in animals and plants that are more closely related hybridization barriers include morphological differences, differing times of fertility, mating behaviors and cues, physiological rejection of sperm cells or the developing embryo.

In plants, barriers to hybridization include blooming period differences, different pollinator vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and structural differences of the chromosomes. [21]

Mythical and legendary hybrids

Ancient folktales often contain mythological creatures, sometimes these are described as hybrids (e. g. Hippogriff as the offspring of a griffin and a horse and the Minotaur which is the offspring of Pasiphaë and a white bull). A Hippogriff (also spelled Hippogryph and Hippogryphe) is a Legendary creature, supposedly the offspring of a Griffin and a mare. The griffin is a Legendary creature with the body of a Lion and the head and often wings of an Eagle. The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. In Greek mythology, the Minotaur ( Greek:, Mīnṓtauros) was a creature that was part man and part bull. In Greek mythology, Pasiphaë (English pəˈsɪfeɪiː Greek: Πασιφάη Pasipháē "wide-shining" was the daughter of Helios More often they are kind of chimera, i. e. a composite of the physical attributes of two or more kinds of animals, mythical beasts, and often humans, with no suggestion that they are the result of interbreeding, e. g. Harpies. In Greek mythology, a harpy ("snatcher" from harpȳia ἅρπυια harpūia) was any one of the mainly winged death-spirits best known for constantly

Etymology

The word has a Latin root: hybrida (or ibrida) which in turn is a loan-word related to Greek hubris (ὕβρις, meaning overbearing pride, outrage), and was meant to be "the offspring of a tame sow and wild boar", probably in interpreting such an offspring as a result of an outrageous "interracial miscegenation". A loanword (or loan word) is a word directly taken into one Language from another with little or no translation Hubris, sometimes spelled hybris ( Ancient Greek ὕβρις is a term used in modern English to indicate overweening Pride, self-confidence Miscegenation (Latin miscere "to mix" + genus "kind" is the mixing of different racial groups, that is marrying, cohabiting The term entered into popular use in English in the 19th century, though examples of its use have been found from the early 17th century. The 19th century of the Common Era began on January 1, 1801 and ended on December 31, 1900, according to the Gregorian calendar As a means of recording the passage of Time, the 17th Century was that Century which lasted from 1601 - 1700 in the Gregorian calendar [22]

See also

References

  1. ^ Keeton, William T. Artificial selection is the intentional breeding for certain traits or combinations of traits over others and is synonymous with " Selective breeding " The Bengal is a relatively new hybrid breed of Cat developed to have a gentle and friendly temperament while exhibiting the "wild" markings (such as large A bird hybrid is basically a Bird that has two different Species as parents In Zoology, a chimera is an animal that has two or more different populations of genetically distinct cells that originated in different Zygotes if the In Greek mythology, the Chimera ( Greek (Chímaira Latin Chimaera) was a monstrous creature of Lycia in Asia Minor Canid hybrids are the result of interbreeding between different species of the canine (dog family ( Canidae) There are a number of hybrids between various Felid species This article deals with hybrids between the smaller felid species and those between smaller felids and F1 hybrid is a term used in Genetics and Selective breeding. F1 stands for Filial 1, the first filial Generation seeds/plants or animal Genetic engineering, Recombinant DNA technology, genetic modification/manipulation (GM and gene splicing are terms that apply to the direct Genetic erosion is a process whereby an already limited Gene pool of an Endangered species of plant or animal diminishes even more when individuals from the surviving Genetic pollution is undesirable Gene flow into wild populations Heterosis is a term used in Genetics and Selective breeding. The term heterosis also known as hybrid vigor or outbreeding enhancement, A parahuman or para-human is a Human - Animal hybrid. Scientists have done extensive research into the combination of Genes from In Botanical nomenclature, a hybrid may be given a hybrid name, which is a special kind of Botanical name. Hybrid speciation is the process wherein Hybridization between two different closely related Species leads to a distinct Phenotype. A hybrid zone exists where the ranges of two Interbreeding Species meet hybrot (short for "hybrid robot" is a Cybernetic organism in the form of a Robot controlled by a Computer consisting of both electronic and biological Inbreeding is breeding between close Relatives whether plant or animal Macropod hybrids are hybrids of animals within the family Macropodidae. Natural selection is the process by which favorable Heritable traits become more common in successive Generations of a Population of Purebreds, also called purebreeds, are cultivated varieties or cultivars of an animal Species, achieved through the process of Selective breeding This article focuses on selective breeding in domesticated animals A sheep–goat hybrid is the hybrid offspring of a Sheep and a Goat. Speciation is the Evolutionary process by which new biological Species arise The Savannah is a hybrid domestic Cat Breed. It is a cross between the Serval and a domestic cat 1980. Biological science. New York: Norton. ISBN 0-393-95021-2 page A9.
  2. ^ Wricke, Gunter, and Eberhard Weber. 1986. Quantitative genetics and selection in plant breeding. Berlin: W. de Gruyter. Page 257.
  3. ^ J. O. Rawlings, C. Clark Cockerham Analysis of Double Cross Hybrid Populations. J. O. Rawlings, C. Clark Cockerham Biometrics, Vol. 18, No. 2 (Jun. , 1962), pp. 229-244 doi:10. 2307/2527461
  4. ^ Roy, Darbeshwar. 2000. Plant breeding analysis and exploitation of variation. Pangbourne, UK: Alpha Science International. Page 446.
  5. ^ Keeton, William T. 1980. Biological science. New York: Norton. ISBN 0-393-95021-2 Page 800
  6. ^ McBeath S, Tan PP, Bai Q, Speed RM. (1988).
  7. ^ MCDB 2150 - Lecture 33
  8. ^ Evaluating the utility of Arabidopsis thaliana as a model for understanding heterosis in hybrid crops Journal Euphytica Publisher Springer Netherlands ISSN 0014-2336 (Print) 1573-5060 (Online) Issue Volume 156, Numbers 1-2 / July, 2007 DOI 10. 1007/s10681-007-9362-1 Pages 157-171
  9. ^ "Hybrid bear shot dead in Canada", BBC News, 2006-05-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1497 - Pope Alexander VI excommunicates Girolamo Savonarola.  
  10. ^ McCarthy, Eugene M. 2006. Handbook of Avian Hybrids of the World. Oxford: Oxford University Press. Pp. 16-17.
  11. ^ McCarthy, Eugene M. 2006. Handbook of Avian Hybrids of the World. Oxford: Oxford University Press. Pp. 16-17.
  12. ^ McCarthy, Eugene M. 2006. Handbook of Avian Hybrids of the World. Oxford: Oxford University Press. P. 17.
  13. ^ Darwin, C. 1868. Variation of Animals and Plants under Domestication, vol. II, p. 125
  14. ^ Spicer, J. W. G. 1854. Note on hybrid gallinaceous birds. The Zoologist, 12: 4294-4296 (see p. 4295).
  15. ^ H. A. Mooney and E. E. Cleland (2001) Hybridization and Introgression; Extinctions; from "The evolutionary impact of invasive species; Proc Natl Acad Sci U S A. 98(10): 5446–5451. doi: 10. 1073/pnas. 091093398.
  16. ^ Rhymer JM and Simberloff, D. (1996) Extinction by Hybridization and Introgression. Annual Review of Ecology and Systematics 27: 83-109 (doi:10. 1146/annurev. ecolsys. 27. 1. 83], [1]
  17. ^ Brad M. Potts, Robert C. Barbour, Andrew B. Hingston (2001) Genetic Pollution from Farm Forestry using eucalypt species and hybrids; A report for the RIRDC/L&WA/FWPRDC; Joint Venture Agroforestry Program; RIRDC Publication No 01/114; RIRDC Project No CPF - 3A; ISBN 0 642 58336 6; ISSN 1440-6845; Australian Government, Rural Industrial Research and Development Corporation
  18. ^ Devinder Sharma “Genetic Pollution: The Great Genetic Scandal”; Bulletin 28. hosted by www. farmedia. org
  19. ^ Michael Pollan (2001) THE YEAR IN IDEAS: A TO Z.; Genetic Pollution; The New York Times, December 9
  20. ^ Norman C. Ellstrand (2003) Dangerous Liaisons? When Cultivated Plants Mate with Their Wild Relatives; The Johns Hopkins University Press, 268 pp. ISBN 0-8018-7405-X.
    Book Reviewed by Steven H Strauss & Stephen P DiFazio: Hybrids abounding; Nature Biotechnology 22, 29 - 30 (2004) doi:10. 1038/nbt0104-29
  21. ^ Barriers to hybridization of Solanum bulbocastanumDun. and S. VerrucosumSchlechtd. and structural hybridity in their F1 plants Journal Euphytica Publisher Springer Netherlands ISSN 0014-2336 (Print) 1573-5060 (Online) Issue Volume 25, Number 1 / January, 1976 Category Articles DOI 10. 1007/BF00041523 Pages 1-10
  22. ^ Oxford English Dictionary Online, Oxford University Press 2007.

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