Abstract
North America has seen a massive increase in cropland use since 1800, accompanied more recently by the intensification of agricultural practices. Through genome analysis of present-day and historical samples spanning environments over the last two centuries, we studied the impact of these changes in farming on the extent and tempo of evolution in the native common waterhemp (Amaranthus tuberculatus), a now pervasive agricultural weed. Modern agriculture has imposed strengths of selection rarely observed in the wild (0.027-0.10), with striking shifts in allele frequency trajectories since agricultural intensification in the 1960s. An evolutionary response to this extreme selection was facilitated by a concurrent human-mediated range shift. By reshaping genome-wide diversity and variation for fitness, agriculture has driven the success of this 21st-century weed.
One Sentence Summary Modern agriculture has dramatically shaped the evolution of a native plant into an agricultural weed through imposing strengths of selection rarely observed in the wild.
Competing Interest Statement
The authors have declared no competing interest.
