Hybrid

A hybrid is an offspring between two different species, or the offspring between two parents of the same species that differ in one or more heritable characteristics. An example of the first kind of hybrid is a mule, a cross between a female horse (Equus caballus ) and a male donkey (E. asinus ). An example of the second kind is the offspring from a cross between true-breeding red- and white-flowered garden peas (Pisum sativum ).

Hybrids between species are often sterile because they fail to produce viable reproductive cells that is, eggs, sperm, or spores. These cells develop improperly because the chromosomes from one species do not pair correctly during meiosis with the chromosomes from the other species.

Despite their sterility, hybrids may thrive and expand their ranges by reproducing asexually. For example, in the eastern United States and adjacent Canada, there are hundreds of distinctive hybrids of hawthorn (Crataegus ) and blackberry (Rubus ) that are not interfertile. Yet these hybrids may be common because they are able to set seed from asexually produced embryos, a special form of propagation called apomixis (Greek apo, away from, and mixis, mix, union—referring to the lack of fertilization). Also, in blackberries, the first-year stems are able to root at the tip, a form of propagation called vegetative reproduction.

Some hybrids become fertile by doubling their chromosome number, a process called polyploidy. Hybridization followed by polyploidy has been extremely important in plantevolution, especially among ferns and grasses. Examples are the wheats used to make bread and pastas, and species of wood fern (Dryopteris ) and spleenworts (Asplenium ).

Hybrids are generally infrequent in nature. Nevertheless, once formed they may be important for evolution because of the way they combine the characteristics of their parents. Especially in changing or disturbed habitats, hybrids that contain new genetic combinations may be better adapted to the new environments than either of the parents. Thus they may be able to colonize new habitats where neither parent can grow.

See also Asexual reproduction; Genetics.

Hybrid

A hybrid is an offspring between two different species , or the offspring between two parents of the same species that differ in one or more heritable characteristics. An example of the first kind of hybrid is a mule, a cross between a female horse (Equus caballus) and a male donkey (E. asinus). An example of the second kind is the offspring from a cross between true-breeding redand white-flowered garden peas (Pisum sativum).

Hybrids between species are often sterile because they fail to produce viable reproductive cells that is, eggs, sperm, or spores. These cells develop improperly because the chromosomes from one species do not pair correctly during meiosis with the chromosomes from the other species.

Despite their sterility, hybrids may thrive and expand their ranges by reproducing asexually. For example, in the eastern United States and adjacent Canada, there are hundreds of distinctive hybrids of hawthorn (Crataegus) and blackberry (Rubus) that are not inter-fertile. Yet these hybrids may be common because they are able to set seed from asexually produced embryos, a special form of propagation called apomixis (Greek apo, away from, and mixis, mix, union—referring to the lack of fertilization ). Also, in blackberries, the first-year stems are able to root at the tip, a form of propagation called vegetative reproduction.

Some hybrids become fertile by doubling their chromosome number, a process called polyploidy. Hybridization followed by polyploidy has been extremely important in plant evolution, especially among ferns and grasses . Examples are the wheats used to make bread and pastas, and species of wood fern (Dryopteris) and spleenworts (Asplenium).

Hybrids are generally infrequent in nature. Nevertheless, once formed they may be important for evolution because of the way they combine the characteristics of their parents. Especially in changing or disturbed habitats, hybrids that contain new genetic combinations may be better adapted to the new environments than either of the parents. Thus they may be able to colonize new habitats where neither parent can grow.

See also Asexual reproduction; Genetics.

hy·brid / ˈhīˌbrid/ • n. a thing made by combining two different elements; a mixture: the final text is a hybrid of the stage play and the film. ∎  Biol. the offspring of two plants or animals of different species or varieties, such as a mule (a hybrid of a donkey and a horse): a hybrid of wheat and rye. ∎ offens. a person of mixed racial or cultural origin. ∎  a word formed from elements taken from different languages, for example television (tele- from Greek, vision from Latin). ∎  a hybrid car. • adj. of mixed character; composed of mixed parts: Mexico's hybrid postconquest culture. ∎  bred as a hybrid from different species or varieties: a hybrid variety hybrid offspring. DERIVATIVES: hy·brid·ism / ˈhībrəˌdizəm/ n. hy·brid·i·ty / hīˈbriditē/ n.

hybrid
1. An individual plant or animal resulting from a cross between parents of differing genotypes. Strictly, most individuals in an outbreeding population are hybrids, but the term is more usually reserved for cases in which the parents are individuals whose genomes are sufficiently distinct for them to be recognized as different species or subspecies. A good example is Spartina town-sendii, produced by cross-breeding Spartina maritima (British cord grass) and the North American species Spartina alterniflora (each of which can breed true as a species). Hybrids may be fertile or sterile depending on qualitative and/or quantitative differences in the genomes of the two parents. Hybrids like Spartina townsendii, whose parents are of different species, are sterile, but generally reproduce vegetatively.

2. By analogy with (1), any heterozygote. Each heterozygote represents dissimilar alleles at a given locus, and this difference results from a cross between parental gametes possessing differing alleles at that locus.

3. (graft hybrid) see GRAFT.

hybrid
1. An individual animal that results from a cross between parents of differing genotypes. Strictly, most individuals in an outbreeding population are hybrids, but the term is more usually reserved for cases in which the parents are individuals whose genomes are sufficiently distinct for them to be recognized as different species or subspecies. A good example is the mule, produced by cross-breeding an ass and a horse (each of which can breed true as a species). Hybrids may be fertile or sterile depending on qualitative and/or quantitative differences in the genomes of the two parents. Hybrids like the mule, whose parents are of different species, are frequently sterile.

2. By analogy, any heterozygote. Each heterozygote represents dissimilar alleles at a given locus, and this difference results from a cross between parental gametes possessing differing alleles at that locus.

3. (graft hybrid) See GRAFT.

hybrid
1. An individual plant or animal resulting from a cross between parents of differing genotypes. Strictly, most individuals in an outbreeding population are hybrids, but the term is more usually reserved for cases in which the parents are individuals whose genomes are sufficiently distinct for them to be recognized as different species or subspecies. Good examples include the mule, produced by cross-breeding an ass and a horse (each of which can breed true as a species) and Spartina townsendii, produced by cross-breeding Spartina maritima (British cord grass) and the North American species Spartina alterniflora (each of which can breed true as a species). Hybrids may be fertile or sterile, depending on qualitative and/or quantitative differences in the genomes of the two parents. Hybrids like Spartina townsendii, whose parents are of different species, are sterile but generally reproduce vegetatively.

2. By analogy with (1), any heterozygote. Each heterozygote represents dissimilar alleles at a given locus, and this difference results from a cross between parental gametes possessing differing alleles at that locus.

3. (graft hybrid) See graft.

HYBRID, also hybrid word. A WORD whose elements come from more than one language: television (from Greek tele-, Latin vision), jollification (from English jolly, Latin -ification). Attitudes to hybrids have been influenced by views on propriety and aesthetics. Traditionally, they have been considered barbarisms; purists have assumed that just as Latin, Greek, French, and English are distinct languages, so elements from these languages within English should be distinct. Hybridization has grown steadily in the 20c, with such words as genocide, hydrofoil, hypermarket, megastar, microwave, photo-journalism, Rototiller, Strip-a-gram, volcanology. See AFRICAN ENGLISH, ANGLO-HYBRID, BARBARISM, COMBINING FORM, INDIAN ENGLISH, THEMATIC VOWEL.

hybrid (hī´brĬd), term applied by plant and animal breeders to the offspring of a cross between two different subspecies or species, and by geneticists to the offspring of parents differing in any genetic characteristic (see genetics). The mule, the hybrid steer, and hybrid corn are examples of hybrids produced by breeders, but some animal species may cross-breed in the wild, as the gray wolf and coyote sometimes do. Hybridization between cultivars or varieties is often used in agriculture to obtain greater vigor or growth (heterosis). Hybrid vigor is achieved by crossing two inbred strains (see breeding). The first generation shows greatly increased vigor and a better yield primarily because many genes for recessive, often deleterious, traits from one parent are masked by corresponding dominant genes in the other parent.

hybrid •arid, married •Alfred • Manfred • acrid • Astrid •serried, unburied, viverrid •varied • sacred • hatred • mirid •Mildred • kindred • Wilfred • Ingrid •Winifred • hybrid •florid, forehead, horrid, torrid •storied • Mordred • putrid •hurried, unworried •unwearied • lurid • ascarid •unsalaried • liveried •Abbasid, acid, antacid, flaccid, Hasid, placid •alcid •rancid, unfancied •deuced, lucid, pellucid, Seleucid •cussed • cursed