by applying selective pressure, induce escape mutations in the viral genome. By sequencing the virus from three patients seen before seroconversion, the authors could identify the single founder ...

What was the selective pressure that led to epidermal pigmentation as protection? Skin cancer is unlikely to be a factor, acting too little (in the case of melanoma) or too late in reproductive life.

President Biden complained about selective prosecution and political pressure in a system he has spent his public life ...

The dark variety had always existed in small numbers, but only had a selective advantage when the selection pressure changed.