Bet-Hedgers under Cultivation: Insights into the Domestication of Erect Knotweed from the Field and the Greenhouse

Evolutionary bet-hedging refers to situations in which organisms sacrifice mean fitness for a reduction in fitness variance over time. Germination heteromorphism is the quintessential and most well understood bet-hedging strategy.  It has evolved in many different plants, including the wild progenitors of some crops. Erect knotweed (Polygonum erectum L.), an annual seed crop, was cultivated in Eastern North America between c. 1500-800 BP.  By 800 BP, cultivation had produced a domesticated subspecies with greatly reduced germination heteromorphism.  Field observations and greenhouse experiments explore how domestication could have occurred in this case, with reference to the theory of evolutionary bet-hedging.  Dormancy provides plants a means of escaping adverse conditions in time, while dispersal provides an escape in space.  Farmers relaxed selective pressures for dormancy in erect knotweed by acting as seed dispersers and by creating more homogenous conditions for cultivated plants over many generations.