g640Lecture14

g640Lecture14 - What have we learned about variation...

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Gametic disequilibrium Morphological variation – lots of variation at many loci What have we learned about variation? Protein variation – Heterozygosity • ~3-8% in vertebrates; 10-15% in invertebrates – Polymorphism • 30%+ in vertebrates; 50%+ in invertebrates What have we learned about variation? Nucleic acid variation – Nucleotide diversity • ~0.0007 / nucleotide – Nucleotide polymorphism • ~ 1/1000 – 1/3000 nucleotides variable What have we learned about variation? At the protein level, if 30% of loci are variable in humans – 10,000+ loci are variable – 400 - 500 loci per “average” chromosome – loci on the same chromosomes are not inherited independently •l inkage What have we learned about variation? At the nucleic acid level, if 0.05% of nucleotides are variable in humans – 1,650,000 + sites are variable – ~ 72,000 sites per “average” chromosome – Sites on the same chromosomes are not inherited independently What have we learned about variation?
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What happens to HW conditions for more than one locus? Linkage Disequilibrium and nonrandom association how many genotypes consider the two locus / two allele model – locus “A” with alleles A and a – locus “B” with alleles B and b need to follow gametic types haplotypes – sets of alleles which are inherited together in one gamete need to follow gametic types haplotypes – sets of alleles which are inherited together in one gamete • could represent: – loci along one chromosome numbers represent allele type at various sites need to follow gametic types haplotypes – sets of alleles which are inherited together in one gamete • could represent: – loci along one chromosome • could also represent – unlinked alleles packaged together at meiosis need to follow gametic types haplotypes – sets of alleles which are inherited together in one gamete Haplotype (gamete) frequencies – f(AB) = P11 – f(Ab) = P12 – f(aB) = P21 – f(ab) = P22
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are the gametes produced in a “random manner” do the frequencies of the alleles at each locus determine the frequency of the gametic types? – Are gametes produced by randomly packaging alleles from each locus linkage equilibrium P11 = p 1 q 1 P22 = p 2 q 2 P12 = p 1 q 2 P21 = p 2 q 1 where: p i = frequency of the alleles at locus A and q i = frequency of the alleles at locus B what happens if there is nonrandom association?
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This note was uploaded on 07/17/2008 for the course EEOB 640 taught by Professor Fuerst during the Spring '05 term at Ohio State.

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g640Lecture14 - What have we learned about variation...

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