A model for infusion of unrelated material into a breeding population
1998
Zheng, Y.Q. | Andersson, E.W. | Lindgren, D.
A consequence of selection in a closed breeding population is an increased level of relatedness. One remedy to this may be infusion of unrelated genetic material into the breeding population. A model is established to study such infusion assuming that new plus-trees equivalent with the old are available. The model uses group merit as the criterion for balancing genetic gain and relatedness measured by group coancestry. Infusion is optimized by finding the maximum group merit. The model involves variables such as average breeding value, structure (family number and size), heritability, relatedness (group coancestry) and its importance (penalty coefficient), and inbreeding. The most important determinant for infusion is the breeding value of the bred material followed by the relatedness between the selected families. An example with considerable similarities to the Swedish breeding program of Norway spruce and Scots pine was given. For establishing the first generation breeding population, it seems optimal to add about 20% to 25% new plus-tree selections rather than to make all selections in the progenies of the existing untested plus-trees. If the plus-trees were progeny tested, about 5% to 10% new selection seems desirable. For more advanced generations, the desire of infusion depends on progress in breeding value and accumulation of relatedness and inbreeding in the breeding population.
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