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if there is a normal distribution of phenotype
There is an underlying normal distribution of:
-additive
-dominance
-epistasis
-permanent
-termporary
Choose an answer
1 Simply-Inherited Traits 2 Parameter
3 Variation in a herd 4 Common characteristics
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Terms in this set (57)
, Traits affected by
-coat color, horns
Qualitative or categorical
Simply-Inherited Traits
-black/red or horned,polled
-rarely quantitative (numbers)
Affected very little by environment
affected by many genes with no gene having an
override influence
-growth rate, milk production, ribeye area
Polygenic Traits Typically quantitative or continuous in expression
-usually described in a number
-weaning weights, milk yields, ribeye area
Greatly influenced by environment
pregnancy
dystocia
Threshold Traits (polygenic)
natural gait
-influenced by many genes but have an either/or result
Which trait tends to be Polygenic Traits
more important -traits that determine productivity and profitability
Both types of traits are subject to the same Mendelian
Mechanisms
-law of segregation and independent assortment
Common characteristics
Dominance and epistasis affect both
Principles of selection and mating apply to both
-attempt to increase frequencies of favorable alleles
Function of the number of genes involved
-the more genes involved, the more DIFFICULT it is to
observe the effects of individual genes, and therefore
Different Breeding
the less specific info we have about those genes
Approaches
-When a few or one gene affects a trait, the effects of
those genes are WELL UNDERSTOOD
-polled, color
Mating designed to reveal the genotype of an individual
for a small number of loci
Polygenic traits have so many genes affecting them that
Test Mating this is impossible
-cannot observe the effects of specific genes
Have to characterize the net effect
-BV, expected progeny difference