Model of the effect of silencing on the distribution of a TE family. Horizontal lines represent chromosomes in a population sample of eight individuals and are divided by dashed lines into regions of high (left) and low (right) gene density. (A) New TE insertions are distributed randomly along chromosomes. (B) Some insertions become silenced by DNA methylation. mTEs near genes interfere with gene expression, and are removed by purifying selection, while the evolutionary trajectory of other TEs are governed largely by genetic drift. (C) Eventually these processes result in a TE distribution in which most insertions are methylated and sequestered in regions of low gene density.
