... measured.1
Assuming that we've randomized siblings across environments. If we haven't, siblings may resemble one another because of similarities in the environment they experienced, too.
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... measured.2
You'll see the reason for the quotes around genotype in this paragraph and the last a little later. It's a little more complex than what I've suggested.
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... familiar.3
Remember our mother-offspring combinations with Zoarces viviparus?
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... produce.4
To check your understanding of all of this, you might want to try to produce the appropriate table.
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....5
, , and are often referred to as the observational components of variance, because they are estimated from observations we make on phenotypic variation. , , and are often referred to as the causal components of variance, because they represent the gentic and environmental influences on trait expression.
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... half-sibs.6
To see why consider this is so, consider the following: The mean genotypic value of half-sib families with an mother is ; with an mother, ; with an mother, . The equation for the variance of these means is identical to the equation for the covariance among half-sibs.
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... groups.7
With , where is the mean group effect and is random effect on individual in group (with mean 0), .
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... you.8
What did you expect from real data? This example is extracted from Falconer and Mackay, pp. 169-170. See the book for details.
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... environment.9
Notice that this doesn't affect our analysis of half-sib families, i.e., the progeny of different sires, since each father was bred with several females
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....10
See Falconer for details.
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