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Natural Selection Can Create Linkage Disequilibrium. Natural Selection Can Create Linkage Disequilibrium. Detecting Postive Selection by Linkage Disequilibrium. Sabeti, et al . 2002. Admixture Can Create Linkage Disequilibrium. Recombination Reduces Linkage Disequilibrium. Chao’s Paper.
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Detecting Postive Selection byLinkage Disequilibrium Sabeti, et al. 2002
Bacteriophage 6 dsRNA
dsRNA dsRNA dsRNA Müller’s Ratchet The fate of asexually reproducing organisms • Assume a single bacteriophage per bacterium = asexual reproduction
dsRNA Experimental Müller’s Ratchet with 6 0.22 m filter Pseudomonas phaseolicola 40X
dsRNA dsRNA dsRNA dsRNA Paired Growth and Fitness of 6 marked parent Müller parent wt parent marked parent Pseudomonas phaseolicola Pseudomonas alcaligenes Pseudomonas phaseolicola Pseudomonas phaseolicola Wt = Rt/R0 I.e., W37A = (150:200)/(200:200) = 0.75
dsRNA dsRNA Experimental Sex with 6 0.22 m filter Pseudomonas phaseolicola 40X
Diopsids - Stalk-eyed Flies (Cyrtodiopsis dalmanni) • Wilkinson, Amitin & Johns • Integr. Comp. Biol., 2005
Heritability of flower size 1/2h2=0.5
Selection gradient = slope Selection gradient = 0.13 S (selection differential) = selection gradient*variance S = 0.13*5.66 mm = 0.74 mm S = 0.74 mm/14.2 mm mean flower size = 0.05
Expected R = h2S = 1 x 0.05 = 0.05 Observed = 9% larger
Heritability of abdominal bristles in D. melanogaster Clayton, et al. 1957
Flies with >22 bristles bred to create generation 2 • Mean bristle number G1 = 19.3 • Mean bristle number of selected G1 = 22.7 • Mean bristle number G2 = 20.1
G1 n = 115; mean bristle number = = 2221/115 = 19.3 G1 selected n = 22; mean bristles = 22.7 G2 n = 101; mean bristles = 20.1