Population genetics

Population genetics is studied the branch of genetics, inheritance processes within biological populations. It determines the relative frequency of homologous genes ( alleles) in populations ( gene frequency ), and examines its change under the influence of mutation, selection, random genetic drift, the separation of sub-populations and gene flow between populations. She has a great importance in the evolution of research as well as in animal and plant breeding.

An important principle of population genetics is that already in 1908 by Wilhelm Weinberg and Godfrey Harold Hardy independently discovered Hardy -Weinberg law, the case of purely random mating and in the absence of any selection an equilibrium state describes, in which the frequency of the alleles of a gene from generation to generation remains constant.

As an independent research branch, the population genetics established in the 1920s, after Reginald Punnett in 1917 introduced the hitherto almost unnoticed discovery vineyard and Hardy as " Hardy - law" in population biology. The founder of this new branch of research were Sewall Wright, Ronald A. Fisher and JBS Haldane. In the 1930s and 1940s, the population genetics studies have provided a significant contribution to the Association of founded by Charles Darwin 's theory of evolution with upon the connecting of Gregor Mendel genetics in force until today Synthetic theory of evolution by helping to resolve existing contradictions between these theories.

The Hardy - Weinberg equilibrium is a theoretical construct, which corresponds to no real vorfindbare population. In real populations mainly different mechanisms of selection assert that certain alleles prefer over others. However, this leads except in very small populations are not the sole Remaining Stay the " fittest " genotype, but there is always a certain diversity ( polymorphism ) was obtained. The numerous reasons for this are also the subject of population genetic research. One of them is the frequently observed phenomenon of heterosis, which is that heterozygous (heterozygous ) individuals are favored by the selection against homozygous ( homozygote ), so prove to be fitter. In the reverse case, inbreeding turns, so the pairing of genetically closely related or identical individuals, a disadvantage, which is particularly a result of the increased incidence of recessive genetic diseases.