Selection between breeds, selection within breeds and cross breeding
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heterosis
the advantage in performance above the mid-parent mean
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why is it important to predict selection?
Compare alternate breeding programmes, choose those with high response at minimal cost
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factors that affect raits of genetic gain
Selection differential, heritability and generation interval
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Response to selection
change in mean performance in a population of animals as a result of selection usually per year or generation
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Selection differential (s)
the difference between the mean performance of selected animals (those identified to become parents of the next generation#0 and the overall mean of the group from which they were selected.
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What is S dependent on?
Variation in performance - wider the variation, the higher the selection differential that can be achieved. Proportion of animals selected - fewer top animals selected, higher the selection differential
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Heritability (H^2) (definition 1)
The proportion of the superiority of parents in a trait which, on average, is passed to the offspring
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Heritability (H^2) (definition 2)
Additive genetic variation in the trait (or variation in breeding values), as expressed as a proportion of the total phenotypic variation of the trait
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Generation Interval (L)
average age of parents when their offspring are born
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Are generations intervals calculated together or seperately for gender of parents?
Separately then averaged
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Annual response to selection is highest when
Selection intensity is high, heritability is low and generation interval is low
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Other cards in this set
Card 2
Front
heterosis
Back
the advantage in performance above the mid-parent mean
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