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Selective sweeps provide a baseline from which different varietals could have emerged. [10] For example, recent study of the corn genotype uncovered dozens of ancient selective sweeps uniting modern cultivars on the basis of shared genetic data possibly dating back as far as domestic corn's wild counterpart, teosinte. In other words, though ...
A multiple origin soft sweep happens when mutations are common, for example in a large population, so that the same or similar beneficial mutations occur on a different genomic background such that no single genomic background can hitchhike the high frequency. [2] Whether the selective sweep has occurred can be explored in various ways.
Genetic hitchhiking, also called genetic draft or the hitchhiking effect, [1] is when an allele changes frequency not because it itself is under natural selection, but because it is near another gene that is undergoing a selective sweep and that is on the same DNA chain.
Due to the outgroup species, you can now tell what the ancestral state of the allele was before the two lineages split. If, for example, the ancestral allele was different, you can now say that there was a selective sweep in that region (could be due to linkage too). The magnitude of the selective sweep will be decided by the strength of H.
For example, one analysis suggests that larger populations have more selective sweeps, which remove more neutral genetic diversity. [68] A negative correlation between mutation rate and population size may also contribute. [69] Life history affects genetic diversity more than population history does, e.g. r-strategists have more genetic ...
In 2014, Lee, Langley, and Begun conducted another research study related to gene fixation. They focused on Drosophila melanogaster population data and the effects of genetic hitchhiking caused by selective sweeps. Genetic hitchhiking occurs when one allele is strongly selected for and driven to fixation.
Tajima's D is a population genetic test statistic created by and named after the Japanese researcher Fumio Tajima. [1] Tajima's D is computed as the difference between two measures of genetic diversity: the mean number of pairwise differences and the number of segregating sites, each scaled so that they are expected to be the same in a neutrally evolving population of constant size.
Example of Neutral Evolution - No Selection. A test that suggests selection: Again suppose you have data as in the last example, only this time locus 2 has equal divergence to locus 1 and yet lower polymorphism in species B. In this case the rate of mutation in each locus is equal, so this can only be explained by a reduction in the effective ...