Post on 31-Dec-2015
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Bio 261September 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
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13C Content
Kasalath x Nipponbare
Lemont x Teqing
Oryza wild species
O.sativa
Rufipogon x Jefferson
IR64 x Nipponbare
variation in leaf-level water use efficiency in rice
McCouch et al., unpublished
rice (Kasalath x Nipponbare) WUE QTL
QTL mapping in Arabidopsis
Hoekenga et al. (2003) Plant Physiol. 132:936-48.
QTL map for root length at day 6, in liquid medium containing Aluminum
Arabidopsis Al-toleranceQTL both affect malate release
-What are the loci underlying speciation and species differentiation?- How did they arise?- What forces have shaped them?
the genus Mimulus
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)
Isolation via pollinators and habitat in
M. lewisii vs. 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%.
lewisii F1 cardinalis
F2
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)
Duke Univ. John Willis
Fred Dietrich
Univ. of Washington Toby Bradshaw
CUGI Jeffery Tomkins
UNC Chapel HillTodd Vision
Michigan State Univ. Doug Schemske
Univ. of MontanaLila Fishman
comparative maps
Livingstone et al 1999 Genetics 152:1183Gale & Devos 1998 PNAS 95:1972
Lycopersicon (tomato) vs. Capsicum (pepper)
Molecular footprint of selection
Neutrality
Populationbottleneck
Selectionnear locus 2
locus1 2 3
Schlotterer (2003) TIG 19, 32
Genomic technologyMolecular evolution and
population genetics
Field ecologyA rich and tractable biological system
Molecular genetic architecture of
species differentiation