Glyphosate resistance evolution to lethal and sublethal doses in chemostat populations of model organism Chlamydomonas reinhardtii

Abstract

Herbicide resistant weeds are an increasing economic and ecological problem world-wide. Evolutionary theory and insight from experiments testing this theory are now a central part of solving resistance problems. More specifically, experimental evolution, where populations are allowed to evolve under specific conditions, can offer substantial insights into the trade-offs that govern the pace at which resistance arises. Here we leverage the green alga Chlamydomonas reinhardtii facing glyphosate as a model plant system to evaluate such theory, monitoring the level of evolved resistance and associated fitness costs throughout the course of adaptation. On a gradient of lethal and sub-lethal doses of glyphosate, we found evidence for evolved resistance from standing genetic variation but limited evidence for classic growth rate trade-offs that are expected to affect the pace of resistance evolution.