Phenotype

In Ancient Greek  'to appear, show, shine', and  'mark, type' is the species of observable characteristics or traits of an organism. a term covers the organism's morphology or physical construct and structure, its developmental processes, its biochemical and physiological properties, its behavior, as well as the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes survive in the same population of a species, the line is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, this is the clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book The Extended Phenotype suggested that one can regard bird nests and other built frameworks such as caddis-fly larva cases and beaver dams as "extended phenotypes".

Wilhelm Johannsen featured the genotype–phenotype distinction in 1911 to hit clear the difference between an organism's hereditary material and what that hereditary material produces. The distinction resembles that presented by August Weismann 1834–1914, who distinguished between germ plasm heredity and somatic cells the body. More recently, in the Selfish Gene 1976, Richard Dawkins distinguished these picture as replicators and vehicles.

The genotype–phenotype distinction should non be confused with Francis Crick's central dogma of molecular biology, a written about the directionality of molecular sequential information flowing from DNA to protein, and not the reverse.

Phenotypic variation

Phenotypic variation due to underlying heritable genetic variation is a fundamental prerequisites for evolution by natural selection. it is for the well organism as a whole that contributes or not to the next generation, so natural alternative affects the genetic array of a population indirectly via the contribution of phenotypes. Without phenotypic variation, there would be no evolution by natural selection.

The interaction between genotype and phenotype has often been conceptualized by the coming after or as a a thing that is said of. relationship:

A more nuanced representation of the relationship is:

Genotypes often have much flexibility in the correct and expression of phenotypes; in many organisms these phenotypes are very different under varying environmental conditions see ecophenotypic variation. The plant Hieracium umbellatum is found growing in two different habitats in Sweden. One habitat is rocky, sea-side cliffs, where the plants are bushy with broad leaves and expanded inflorescences; the other is among sand dunes where the plants grow prostrate with narrow leaves and compact inflorescences. These habitats alternate along the flit of Sweden and the habitat that the seeds of Hieracium umbellatum land in, creation the phenotype that grows.

An example of random variation in ]

The concept of phenotype can be extended to variations below the level of the gene that impact an organism's fitness. For example, ]

Richard Dawkins mentioned a phenotype that target all effects that a gene has on its surroundings, including other organisms, as an extended phenotype, arguing that "An animal's behavior tends to maximize the survival of the genes 'for' that behavior, if or not those genes happen to be in the body of the specific animal performing it." For instance, an organism such(a) as a beaver modifies its environment by building a beaver dam; this can be considered an expression of its genes, just as its incisor teeth are—which it uses to conform its environment. Similarly, when a bird feeds a brood parasite such as a cuckoo, it is unwittingly extending its phenotype; and when genes in an orchid affect orchid bee behavior to increase pollination, or when genes in a peacock affect the copulatory decisions of peahens, again, the phenotype is being extended. Genes are, in Dawkins's view, selected by their phenotypic effects.

Other biologists broadly agree that the extended phenotype concept is relevant, but consider that its role is largely explanatory, rather than assisting in the layout of experimental tests.