Shifts in outcrossing rates and changes to floral traits are associated with the evolution of herbicide resistance in the common morning glory

Abstract

Humanâ mediated selection can strongly influence the evolutionary response of natural organisms within ecological timescales. But what traits allow for, or even facilitate, adaptation to the strong selection humans impose on natural systems? Using a combination of laboratory and greenhouse studies of 32 natural populations of the common agricultural weed, Ipomoea purpurea, we show that herbicideâ resistant populations selfâ fertilise more than susceptible populations. We likewise show that antherâ stigma distance, a floral trait associated with selfâ fertilisation in this species, exhibits a nonlinear relationship with resistance such that the most and least resistant populations exhibit lower antherâ stigma separation compared to populations with moderate levels of resistance. Overall, our results extend the general finding that plant mating can be impacted by humanâ mediated agents of selection to that of the extreme selection of the agricultural system. This work highlights the influence of humanâ mediated selection on rapid responses of natural populations that can lead to unexpected longâ term evolutionary consequences.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135395/1/ele12703_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135395/2/ele12703.pd