Selektionsparamter

Selektionsparamter is a term used in evolutionary biology, quantitative genetics and breeding to denote the parameters that quantify the strength and pattern of selection acting on genetic variants or phenotypes. In natural populations, two main kinds of parameters are used: the selection coefficient s, describing the relative fitness difference of a genotype, and the dominance parameter h, describing how fitness is expressed in heterozygotes. Fitness values for genotypes (for example w_AA, w_Aa, w_aa) are used to predict changes in allele frequencies under selection.

In quantitative genetics, the framework uses the selection differential S and the response to selection R, with the breeder’s equation R = h^2 S, where h^2 is heritability. The selection intensity i and the phenotypic standard deviation σ_p relate to S via S = i σ_p. These parameters help connect observed phenotypic shifts to underlying genetic gains.

In population genetics, a related metric is 2Ns, which compares the strength of selection to genetic drift. If 2Ns is much greater than 1, selection tends to dominate drift; if it is much less than 1, drift plays a larger role. This helps interpret evolutionary dynamics in small versus large populations.

In artificial selection or breeding programs, Selektionsparameter guide decisions about which individuals to propagate, with emphasis on selection intensity, accuracy of selection, and generation interval. In practice, these parameters are estimated from data or inferred from models and are essential for forecasting evolutionary trajectories or optimizing genetic gain in breeding efforts.