Selective sweep of a new advantageous mutation in the absence of recombination
A novel SNP mutation is indicated by the red star. It necessarily
arises in a single individual, who is one of a population
of individuals with a variety of patterns of genetically
linked SNPs (haplotypes). Note in the
example the 1st & 2nd, and 4th & 5th
haplotypes from the top are identical. With respect to
the novel SNP, the
linked SNP to the left is shared with the the two
haplotypes immediately above it, which is an indication of
common ancestry; the SNP all the way to the right
is unique.
Strong positive selection for the novel red SNP may take it to fixation in a few generations, and the other linked SNPS in the immediately surrounding gene region will also become fixed, even though they are selectively neutral, with no selective advantage in themselves. Natural Selection therefore "sweeps" all genetic variation out of the chromosome region.
Strong positive selection for the novel red SNP may take it to fixation in a few generations, and the other linked SNPS in the immediately surrounding gene region will also become fixed, even though they are selectively neutral, with no selective advantage in themselves. Natural Selection therefore "sweeps" all genetic variation out of the chromosome region.
The utility of
neutral markers to detect genetically-linked
disease SNPs was
discussed in Biol2250.
Figures © 2013 by Sinauer; Text material © 2018 by Steven M. Carr