Evaluating Genetic Changes Associated with Selection Utilizing Information from Diallel Mating Designs1
- W. D. Hanson2
This study compares the generation mean analysis and the diversity analysis as analytical tools and evaluates changes resulting from a selection program. Genotypic values for diallel matings between base populations and selections from these base populations were expressed in terms of parameters containing both additive and nonadditive gene effects. These parameters directly translated to those based on the assumption of additive effects among loci. The mean analysis provides information on the variability associated with realized gains. The diversity analysis provides information on the nature of divergence due to selection. Published results from reciprocal recurrent (RRS) and half-sib (HSS) selection in maize (Zea mays L.) were reevaluated using the diversity analysis. The mean analysis had yielded estimates for direct and indirect responses to selection. Both selection schemes effectively increased grain yield in maize. Divergence from the base populations occurred for genes having additive-associated and dominance-associated gene effects under both RRS and HSS. The basis for divergence was not associated with the selection scheme. Divergence of the two selected populations from their base populations under RRS was parallel-like, supporting the conclusion that grain yield depended primarily on genes having partial to complete dominance effects. Selection based on top-cross performance (HSS) emphasized a set of dominance-associated gene effects different from RSS. Distances obtained from the diversity analysis correlated (+0.89) with distances reflecting inbreeding depressions obtained when corresponding gene pools were combined.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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