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Lecture 1: Genomics approaches for analyses of population structure

Lecture 1: Genomics approaches for analyses of population structure. Tom Turner & Matt Hahn UI Bloomington Kristy Harmon & Larry Harshman UN Lincoln Eric von Wettberg, Sharon Strauss & Tom Turner

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Lecture 1: Genomics approaches for analyses of population structure

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  1. Lecture 1: Genomics approaches for analyses of population structure Tom Turner & Matt Hahn UI Bloomington Kristy Harmon & Larry Harshman UN Lincoln Eric von Wettberg, Sharon Strauss & Tom Turner Brian Dilkes, Shelley McMahon & Peter Chang UA Tucson USouthCal

  2. Four topics of the talk: • Genomics of mosquito incipient speciation • Genome-enabled hitchhiking mapping in flies • Genomics of local adaptations in diploid mustards • Genomics of tetraploidy in mustards

  3. Anopheles gambiae ? X chromosome polymorphism ♀ ( ♂) – share allele ♀ ( ♂) – share allele ~1% ♀ ( ♂), ♀ ( ♂) - don’t share

  4. Affymetrix microarray: 142K oligonucleotides 25 bp each. Normal use: RNA We used: DNA Multiple samples per race. S: --------------M: -------------- S: -------------- M: -------------- S: --------------M: --------------

  5. What Component of the Genome Is Not Shared between the Races? S: -------------- M: -------------- S: -------------- M: -------------- S: -------------- M: --------------

  6. Support from Re-Sequencing?

  7. Conclusions:Genomics of Mosquito Incipient Speciation • natural hybrid zones are a powerful tool of genetic (genomic) analysis; • three “speciation islands” ( X and II) contain 67 genes (including olfactory receptors with signatures of natural selection); • the rest of the genome is shared between the races.

  8. Four topics of the talk: • Genomics of mosquito incipient speciation • Genome-enabled hitchhiking mapping in flies • Genomics of local adaptations in diploid mustards • Genomics of tetraploidy in mustards

  9. “Normal” Approaches for the Analysis of Variation • Identify two “interesting” genotypes; • Cross them to generate mapping population; • Genotype hundred(s) of recombinant individuals / genotypes; • Analyze QTLs. = long, boring, labor-intensive.

  10. Selection for starvation / oxidation resistances

  11. How to analyze numerous dense markers? Microsatellites? AFLPs?  SNPs ~2b out of 100 are different between flies. 3 selected 3 control X 3 chips = 9 X 3 chips = 9  high false discovery rate (up to 50%)  analyze CLUMPS of significances (1Mb)

  12. Genome - Enabled Hitch-Hiking Mapping Two QTLs primarily accounted for selection response… but are they real? Confirmed by pyrosequencing!

  13. Four topics of the talk: • Genomics of mosquito incipient speciation • Genome-enabled hitchhiking mapping in flies • Genomics of local adaptations in diploid mustards • Genomics of tetraploidy in mustards

  14. Sequence divergence, how much does it matter? Arabidopsis lyrata ~95% seq. identity ~tiling Arabidopsis array: ~3M PM/MM features 2 populations on normal 2 on serpentine X 3 chips  12 arrays

  15. Sequence divergence matters 95% sequence identity   1 b out of 25 are divergent 2853369 PMs on the array   371642 are matches 28 (p<0.05 Bonferroni); 72 (FDR<1%); 362 (FDR<5%).

  16. Preliminary conclusions 14 probes would be significant P<0.01 (assuming 2853369 tests) 5 (3) highly significant probes map to AT5G17740(AAA-type ATPase family protein, members of gene family have been implicated in salt stress adaptation)

  17. Other candidate genes: - “similar to early-responsive to dehydrationprotein-related" gene; • a receptor-like kinase that has serine/threoninekinase activity whose expression is induced by high salt stress; • many golgi/ER and transport related genes, including cation transporters.

  18. Four topics of the talk: • Genomics of mosquito incipient speciation • Genome-enabled hitchhiking mapping in flies • Genomics of local adaptations in diploid mustards • Genomics of tetraploidy in mustards

  19. Chips  Evolution A. thalianaA. arenosa p = 0.01 1 2 3 4 5 138537 88691 104753 82545 117708 0.389 0.385 0.369 0.382 0.377

  20. Chips  Evolution A. thaliana +A. arenosa = F1 hybrid A. suecica Probes % of F1 / A. suecica classified as: • thaliana 2 / 9 mix 88 / 69 A. arenosa 10 / 22

  21. Chips  Evolution • False discoveries or deletions within species? • Deletions after tetraploid formation (9-10% of both parents)  genes / pathways / ecology? • Evolution of allele-specific expression  genes / pathways / chromosomal positions?

  22. Follow up comments Chips?  Ilumina 454 Solexa  $5K = 40M reads / 30b = = 1.2G or 8 x Drosophila coverage  4 reads H Ni 25x + 4 reads L Ni 25x

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