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Human Population Genetics. Human population migrations. Out of Africa, Replacement Single mother of all humans (Eve) ~150,000yr Single father of all humans (Adam) ~70,000yr Humans out of Africa ~40000 years ago replaced others (e.g., Neandertals ) Evidence: mtDNA , Y chromosome

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Human population migrations
Human population migrations

  • Out of Africa, Replacement

    • Single mother of all humans (Eve) ~150,000yr

    • Single father of all humans (Adam) ~70,000yr

    • Humans out of Africa ~40000 years ago replaced others (e.g., Neandertals)

    • Evidence: mtDNA, Y chromosome

  • Multiregional Evolution

    • Fossil records show a continuous change of morphological features

    • Proponents of the theory doubt mtDNA and other genetic evidence


Why humans are so similar
Why humans are so similar

A small population that interbred reduced the genetic variation

Out of Africa ~ 40,000 years ago

Out of Africa



Migration of humans1
Migration of Humans

http://info.med.yale.edu/genetics/kkidd/point.html



Migration of humans3
Migration of Humans

http://info.med.yale.edu/genetics/kkidd/point.html



Some key definitions
Some Key Definitions

Mary: AGCCCGTACG

John: AGCCCGTACG

Josh: AGCCCGTACG

Kate: AGCCCGTACG

Pete: AGCCCGTACG

Anne: AGCCCGTACG

Mimi: AGCCCGTACG

Mike: AGCCCTTACG

Olga: AGCCCTTACG

Tony: AGCCCTTACG

G/G

G/G

G/T

G/G

G/G

G/G

G/G

T/T

T/G

T/G

Mom

Dad

Recombinations:

At least 1/chromosome

On average ~1/100 Mb

  • Heterozygosity:

  • Prob[2 alleles picked at random with replacement are different]

    • 2*.75*.25 = .375

  • H = 4Nu/(1+4Nu)

  • Alleles: G, T

    Major Allele: G

    Minor Allele: T

    Linkage Disequilibrium:

    The degree of correlation between two SNP locations


    The fall in heterozygosity
    The Fall in Heterozygosity


    The hapmap project
    The HapMap Project


    The hapmap project1
    The HapMap Project


    The hapmap project haplotype blocks
    The HapMap Project – Haplotype Blocks


    The hapmap project ld
    The HapMap Project – LD


    Fixation positive negative selection
    Fixation, Positive & Negative Selection

    How can we detect negative selection?

    How can we detect positive selection?

    Negative Selection

    Neutral Drift

    Positive Selection


    Conservation and human snps
    Conservation and Human SNPs

    Neutral

    CNS

    CNSs have fewer SNPs

    SNPs have shifted allele frequency spectra


    How can we detect positive selection
    How can we detect positive selection?

    Ka/Ks ratio:

    Ratio of nonsynonymous to

    synonymous substitutions

    Very old, persistent, strong positive selection for a protein that keeps adapting




    Long haplotypes ihs test
    Long Haplotypes –iHS test



    Example microencephalin gene
    Example: Microencephalin gene