F1 hybrid
Encyclopedia
F1 hybrid is a term used in genetics
and selective breeding
. F1 stands for Filial 1, the first filial generation
seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types.
The term is sometimes written with a subscript, as F1 hybrid.
The offspring of distinctly different parental types produce a new, uniform variety with specific characteristics from either or both parents. In fish breeding, those parents frequently are two closely related fish species, while in plant and animal genetics those parents usually are two inbred lines. Mule
s are F1 hybrids between horse
and donkey
. Today, certain domestic hybrid breeds, such as the Savannah cat
, are classified by their filial generation number.
Gregor Mendel
's groundbreaking work in the 19th century focused on patterns of inheritance
and the genetic
basis for variation. In his cross-pollination experiments involving two true-breeding, or homozygous, parents, Mendel found that the resulting F1 generation were heterozygous and consistent. The offspring showed a combination of those phenotypes from each of the parents that were genetically dominant. Mendel’s discoveries involving the F1 and F2 generation laid the foundation for modern genetics.
(plant) by means of controlled pollination
. To produce consistent F1 hybrids, the original cross must be repeated each season. As in the original cross, in plants this is usually done through controlled hand-pollination, and explains why F1 seeds can often be expensive. F1 hybrids can also occur naturally, a prime example being peppermint
, which is not a species evolve
d by cladogenesis
or gradual change from a single ancestor, but a sterile
stereotyped hybrid of watermint and spearmint. Unable to produce seeds, it propagates through the vining spread of its own root system.
In agronomy
, the term “F1 hybrid” is usually reserved for agricultural cultivar
s derived from two different parent cultivars, each of which are inbred for a number of generations to the extent that they are almost homozygous. The divergence between the parent lines promotes improved growth and yield characteristics through the phenomenon of heterosis
("hybrid vigour"), whilst the homozygosity of the parent lines ensures a phenotypically uniform F1 generation. Each year, for example, specific tomato "hybrids" are specifically recreated by crossing the two parent heirloom
cultivars over again.
Two population
s of breeding stock with desired characteristics are subject to inbreeding
until the homozygosity of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations. After this happens, both populations must be crossed while avoiding self-fertilization. Normally this happens in plants by deactivating or removing male flowers from one population, taking advantage of time differences between male and female flowering or hand-pollinating.
In 1960, 99 percent of all corn planted in the United States
, 95 percent of sugar beet, 80 percent of spinach, 80 percent of sunflowers, 62 percent of broccoli, and 60 percent of onions were hybrid. Such figures are probably higher today. Beans and peas are not commercially hybridized because they are automatic pollinators, and hand-pollination is prohibitively expensive.
, and therefore it is impossible to achieve self-fertilization during an F1 cross. F1 crosses in fish can be between two inbred lines or between two closely related fish species, such as cichlid
subspecies. The cross is usually performed by natural or artificial insemination
.
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and selective breeding
Selective breeding
Selective breeding is the process of breeding plants and animals for particular genetic traits. Typically, strains that are selectively bred are domesticated, and the breeding is sometimes done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties,...
. F1 stands for Filial 1, the first filial generation
Generation
Generation , also known as procreation in biological sciences, is the act of producing offspring....
seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types.
The term is sometimes written with a subscript, as F1 hybrid.
The offspring of distinctly different parental types produce a new, uniform variety with specific characteristics from either or both parents. In fish breeding, those parents frequently are two closely related fish species, while in plant and animal genetics those parents usually are two inbred lines. Mule
Mule
A mule is the offspring of a male donkey and a female horse. Horses and donkeys are different species, with different numbers of chromosomes. Of the two F1 hybrids between these two species, a mule is easier to obtain than a hinny...
s are F1 hybrids between horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
and donkey
Donkey
The donkey or ass, Equus africanus asinus, is a domesticated member of the Equidae or horse family. The wild ancestor of the donkey is the African Wild Ass, E...
. Today, certain domestic hybrid breeds, such as the Savannah cat
Savannah (cat)
The Savannah is a domestic hybrid cat breed. It is a cross between a serval and a domestic cat. -History:...
, are classified by their filial generation number.
Gregor Mendel
Gregor Mendel
Gregor Johann Mendel was an Austrian scientist and Augustinian friar who gained posthumous fame as the founder of the new science of genetics. Mendel demonstrated that the inheritance of certain traits in pea plants follows particular patterns, now referred to as the laws of Mendelian inheritance...
's groundbreaking work in the 19th century focused on patterns of inheritance
Inheritance
Inheritance is the practice of passing on property, titles, debts, rights and obligations upon the death of an individual. It has long played an important role in human societies...
and the genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
basis for variation. In his cross-pollination experiments involving two true-breeding, or homozygous, parents, Mendel found that the resulting F1 generation were heterozygous and consistent. The offspring showed a combination of those phenotypes from each of the parents that were genetically dominant. Mendel’s discoveries involving the F1 and F2 generation laid the foundation for modern genetics.
In plants
Crossing two genetically different plants produces a hybrid seedSeed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
(plant) by means of controlled pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
. To produce consistent F1 hybrids, the original cross must be repeated each season. As in the original cross, in plants this is usually done through controlled hand-pollination, and explains why F1 seeds can often be expensive. F1 hybrids can also occur naturally, a prime example being peppermint
Peppermint
Peppermint is a hybrid mint, a cross between the watermint and spearmint . The plant, indigenous to Europe, is now widespread in cultivation throughout all regions of the world...
, which is not a species evolve
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
d by cladogenesis
Cladogenesis
Cladogenesis is an evolutionary splitting event in a species in which each branch and its smaller branches forms a "clade", an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of sister species...
or gradual change from a single ancestor, but a sterile
Sterility (physiology)
Sterility is the physiological inability to effect sexual reproduction in a living thing, members of whose kind have been produced sexually. The term may be used in reference to* types of organism, such as the mule, a sterile hybrid;...
stereotyped hybrid of watermint and spearmint. Unable to produce seeds, it propagates through the vining spread of its own root system.
In agronomy
Agronomy
Agronomy is the science and technology of producing and using plants for food, fuel, feed, fiber, and reclamation. Agronomy encompasses work in the areas of plant genetics, plant physiology, meteorology, and soil science. Agronomy is the application of a combination of sciences like biology,...
, the term “F1 hybrid” is usually reserved for agricultural cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s derived from two different parent cultivars, each of which are inbred for a number of generations to the extent that they are almost homozygous. The divergence between the parent lines promotes improved growth and yield characteristics through the phenomenon of heterosis
Heterosis
Heterosis, or hybrid vigor, or outbreeding enhancement, is the improved or increased function of any biological quality in a hybrid offspring. The adjective derived from heterosis is heterotic....
("hybrid vigour"), whilst the homozygosity of the parent lines ensures a phenotypically uniform F1 generation. Each year, for example, specific tomato "hybrids" are specifically recreated by crossing the two parent heirloom
Heirloom plant
An heirloom plant, heirloom variety, or heirloom vegetable is a cultivar that was commonly grown during earlier periods in human history, but which is not used in modern large-scale agriculture...
cultivars over again.
Two population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
s of breeding stock with desired characteristics are subject to inbreeding
Inbreeding
Inbreeding is the reproduction from the mating of two genetically related parents. Inbreeding results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is...
until the homozygosity of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations. After this happens, both populations must be crossed while avoiding self-fertilization. Normally this happens in plants by deactivating or removing male flowers from one population, taking advantage of time differences between male and female flowering or hand-pollinating.
In 1960, 99 percent of all corn planted in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, 95 percent of sugar beet, 80 percent of spinach, 80 percent of sunflowers, 62 percent of broccoli, and 60 percent of onions were hybrid. Such figures are probably higher today. Beans and peas are not commercially hybridized because they are automatic pollinators, and hand-pollination is prohibitively expensive.
F2 hybrid
While an F2 hybrid, the result of self or cross pollination of an F1, does not have the consistency of the F1 hybrid, it may retain some desirable traits and can be produced more cheaply as no intervention in the pollination is required. Some seed companies offer F2 seed, particularly in bedding plants where consistency is not as critical.In animals
Unlike most plants, commonly bred fish species as well as all mammals and birds are not hermaphroditicHermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
, and therefore it is impossible to achieve self-fertilization during an F1 cross. F1 crosses in fish can be between two inbred lines or between two closely related fish species, such as cichlid
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...
subspecies. The cross is usually performed by natural or artificial insemination
Artificial insemination
Artificial insemination, or AI, is the process by which sperm is placed into the reproductive tract of a female for the purpose of impregnating the female by using means other than sexual intercourse or natural insemination...
.
Advantages
- Homogeneity and predictability - If the parents are homozygous pure lines, there is limited genetic variation between individual F1 plants or animals. This makes their phenotypePhenotypeA phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
extremely uniform and thus attractive for mechanical operations and makes it easier to fine-tune the management of the populationPopulationA population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
. Once the characteristics of the cross are known, repeating this cross will yield exactly the same result. - Higher performance - As most alleleAlleleAn allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s code for different versions of a proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
or enzymeEnzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
, having two different versions of this allele amounts to having two different versions of the enzyme. This will increase the likelihood of having an optimal version of the enzyme present and reduce the likelihood of a genetic defect. This effect is referred to in genetics as heterosisHeterosisHeterosis, or hybrid vigor, or outbreeding enhancement, is the improved or increased function of any biological quality in a hybrid offspring. The adjective derived from heterosis is heterotic....
. - F1 hybrids can give higher yields than traditional varieties.
Disadvantages
- The main advantage of F1 hybrids in agriculture is also their drawback. When F1 cultivars are used for the breeding of a new generation, their offspring (F2 generation) will vary greatly from one another. Some of the F2 generation will be high in homozygous genes, as found in the weaker parental generation, and these will have a depression in yield and lack the hybrid vigour. From the point of view of a commercial seed producer which does not wish its customers to produce their own seed, this genetic assortment is a desired characteristic.
- Both inbreeding and crossing the lines requires a lot of work, which translates into a much higher seed cost. In general, the higher yield offsets this disadvantage.
- F1 hybrids mature at the same time when raised under the same environmental conditions. This is of interest for modern farmers, because all ripen at the same time and can be harvested by machine. Traditional varieties are often more useful to gardeners because they crop over a longer period of time, avoiding gluts and food shortages.