Genotype

The genotype (Greek genos " kind, gender " and typos " image, pattern ") or the heritage of an organism represents its exact genetic makeup, ie the individual set of genes, which he carries in its cell nucleus and thus its morphological and physiological phenotype determined. The term genotype was coined in 1909 by the Danish geneticist Wilhelm Johannsen.

The genetic information of the entire cell is referred to as idiotype ( idiotype ). Two organisms whose genes differ at only one locus (the position in their genome ) have a different genotype. The term " genotype " thus refers to the complete combination of all alleles / loci of all of an organism. Under phenotype is defined as the sum of all observable characteristics of an organism ( eg size, flower color, beak shape ), which have developed as a result of the interaction of the genotype with the environment. The genotype changes during the lifetime of an organism not, except by accident, such as the influence of radioactive α -, β -, and γ - radiation or by thermal shock.

The greatest influence on the development of an organism has its genotype. But there are other factors that also organisms identical genotype usually differ in their phenotype. Are responsible for this epigenetic mechanisms, ie identical genes may be differentially expressed in various organisms.

An everyday example are monozygotic ( identical ) twins. Identical twins have the same genotype, since they carry the same genome in itself, but never the same phenotype, although they may be very similar. This is reflected in the fact that their parents and close friends can tell them apart at all times, even when other difficult to recognize these subtle differences. In addition, identical twins can be identified by their fingerprints, which are fully equal to never.

Phenotypic plasticity

The concept of phenotypic plasticity describes the degree to which the phenotype of an organism is previously determined by its genotype. A high value of plasticity means that environmental factors have a strong influence on the individually evolving phenotype. At low plasticity of the phenotype can be reliably predicted from the genotype, regardless of special environmental conditions during development. High plasticity can be observed on the example of the larvae of the newt: If these larvae perceive the presence of predators such as dragonflies, the head and the tail larger in proportion to body and skin pigmentation is darker. Larvae with these features have better chances of survival against predators, but grow more slowly than other phenotypes.

Genetic canalization

Main Post: channeling (Development)

In contrast to phenotypic plasticity, the concept of genetic canalization with the question of to what extent the phenotype allows conclusions on the genotype involved. A phenotype is channeled called when mutations ( changes of the genome ) affect the physical characteristics of an organism only imperceptibly. That is, a canalized phenotype can be formed from a wide range of genotypes. In this case, can not be reliably close to the genotype from the knowledge of the phenotype. If there is no channeling, small changes in the genome can exert a direct influence on the developing phenotype.