%0 Research article
%T Phenotypic selection compared to restricted combined index selection for many generations
%A Andersson, Erik W.
%A Spanos, Kostas A.
%A Mullin, Timothy J.
%A Lindgren, Dag
%D 1998
%J Silva Fennica
%V 32
%N 2
%R doi:10.14214/sf.689
%U https://silvafennica.fi/article/689
%X A breeding population has been subjected to repeated selection and  crossing by simulation. Unrestricted phenotypic selection and restricted  combined index selection were compared at the same effective number for  five generations. Results show that phenotypic selection often achieves  the gain and diversity possible to achieve by combined index selection  but the relative efficiency is different for different family sizes and  heritabilities. When phenotypic selection was compared with restricted  combined index method at low heritabilities, both methods performed  almost equally in terms of gain at the same effective number in small  family sizes, although in large families, phenotypic selection was less  efficient. At high heritabilities phenotypic selection was as efficient  as combined index selection. Phenotypic selection was more efficient in  conserving additive variance than combined index selection over five  generations compared at the same gain and effective number. The  introduction of a dominance component to the total variance had little  effect. An increased breeding population size by a factor of ten  resulted in an increased additive gain by app. 15%. The conclusion is  that even though combined index selection is superior in identifying and  extracting the potential for breeding achievements, it is generally not  performing better than mass selection when compared at the same  effective population size in small families.