Quote:
Originally posted by Donut:
Okay BK, here's one that had me stumped for a bit:
Heritability is defined as h2 = Vg / Vp. Explain the meaning of the equation and discuss how one actually goes about estimating heritability.
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Ah, Genetics. h2 is the %% of probability of getting gene you are looking for. Vg is the number of occurances the desired gene is expressed in the possiblities. Vp is total number of possiblities.
The big difficulty comes with dominate and recessive traits. In simple genotypes, there is one dominate and one recessive. If D is Dominate, and r is recessive, and the cross (ie the reproduction process that you should already understand of the parent having two genes and only giving one in reproduction) of two genes between two Dr's lead to 4 possible combos, DD, Dr, Dr, and rr. If their is the Dominate gene (ie D) expressed in the resultant genotype will have that trait expressed. the only time a recessive trait ie r will be expressed is if both genes passed are the recessive ones (rr).
So back to the equation, and using a cross of the two Dr's, the percentage of the domantent trait expressed (ie h2) is going to be all the times the domenant trait is expressed (DD, Dr, Dr) 3 / total combos (4) or 75%. The times the recessive traits are express are . . .yes you in the back? Correct, 25%. It gets more complicated with mulitply traits (also called alleles) like eye color, or blood type, but this is the basics. If you need more info, please click here:
http://www.workingdogs.com/doc0189.htm
Thanks,
BK
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