Selection Effects on Diversity and Genetic Gain

1991

5 Lit. Ang.

Unselbständiges Werk

2767

200040878

Four different methods of truncation selection were studied in a population consisting of a large number of large unrelated full sib families of equal size: phenotypic selection, family selection, within-family selection and combined index selection (optimal weighting of individual and family performance to get the best prediction of breeding value). Methods were developed for calculating diversity ("relative effective family number") for the different selection methods. Numerical calculations were made for genetic gain and diversity. Model assumptions are additive gene control and normal distribution. Combined index maximized gain at a given selection intensity. Phenotypic was good at high heritabilities and between family at low heritabilities. Loss of diversity was strongly dependent on selection method and selection strength. Compared at the same diversity, genetic gain was lower for combined index compared to phenotypic. There is a need for methods combining the goals gain and diversity.