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Bio 261 September 30, 2003 Todd Vision

Bio 261 September 30, 2003 Todd Vision. Genetic Mapping “Speciation QTL” in Mimulus From QTL to an understanding the evolution of species differences at a molecular level. QTL mapping. variation in leaf-level water use efficiency in rice. McCouch et al. , unpublished.

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Bio 261 September 30, 2003 Todd Vision

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  1. Bio 261September 30, 2003Todd Vision • Genetic Mapping • “Speciation QTL” in Mimulus • From QTL to an understanding the evolution of species differences at a molecular level

  2. QTL mapping

  3. variation in leaf-level water use efficiency in rice McCouch et al., unpublished

  4. rice (Kasalath x Nipponbare) WUE QTL

  5. Hoekenga et al. (2003) Plant Physiol. 132:936-48. QTL mapping in Arabidopsis QTL map for root length at day 6, in liquid medium containing Aluminum

  6. Arabidopsis Al-toleranceQTL both affect malate release

  7. What are the loci underlying speciation and species differentiation?- How did they arise?- What forces have shaped them? the genus Mimulus

  8. Hybrid sterility in M. guttatus vs. nasutus • Minor QTL • Differences in floral morphology • Major QTL • a pair of epistatically interacting nuclear loci that cause complete pollen sterility in 1/8 of the hybrid F2 offspring • A cytonuclear incompatibility system causes complete male sterility in 1/4 of offspring carrying the M. guttatus cytoplasm M. nasutus growing in a mixed clump with M. guttatus in Shirley Creek, Calaveras Co, California. The red lines indicate M. nasutus flowers (photo: Mark MacNair)

  9. Isolation via pollinators and habitat inM. lewisii vs. cardinalis lewisii F1 cardinalis • Two major QTL underlying differences in pollination syndrome have been mapped • Introgression of the anthocyanin QTL (yup) from M. cardinalis into M. lewisii reduces bee visitation by 80%. • Allelic substitution from M. lewisii into M. cardinalis at the major nectar QTL (NEC1) reduces hummingbird visitation by 50%. F2

  10. From QTL to gene • QTL intervals contain many genes • To get to causative polymorphisms, these things help: • Nearly isogenic lines (to Mendelize QTL) • Expressed sequence tags (cDNA sequences) • Large collections of markers (SSR, STS) • Comparative maps (e.g. to tomato & Arabidopsis) • Large-insert clones (BAC libraries) • Transgenics (to confirm the mapping results)

  11. Univ. of Washington Toby Bradshaw Michigan State Univ. Doug Schemske Duke Univ. John Willis Fred Dietrich CUGI Jeffery Tomkins Univ. of Montana Lila Fishman UNC Chapel Hill Todd Vision

  12. comparative maps Lycopersicon (tomato) vs. Capsicum (pepper) Gale & Devos 1998 PNAS 95:1972 Livingstone et al 1999 Genetics 152:1183

  13. locus 1 2 3 Neutrality Population bottleneck Selection near locus 2 Molecular footprint of selection Schlotterer (2003) TIG 19, 32

  14. Genomic technology Molecular evolution and population genetics Molecular genetic architecture of species differentiation Field ecology A rich and tractable biological system

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