title: Selection history and epistatic interactions impact dynamics of adaptation to novel environmental stresses.
abstract: In rapidly changing environments, selection history may impact the dynamics of adaptation. Mutations selected in one environment may result in pleiotropic fitness trade-offs in subsequent novel environments, slowing the rates of adaptation. Epistatic interactions between mutations selected in sequential stressful environments may slow or accelerate subsequent rates of adaptation, depending on the nature of that interaction. We explored the dynamics of adaptation during sequential exposure to herbicides with different modes of action in Chlamydomonas reinhardtii. Evolution of resistance to two of the herbicides was largely independent of selection history. For carbetamide, previous adaptation to other herbicide modes of action positively impacted the likelihood of adaptation to this herbicide. Furthermore, while adaptation to all individual herbicides was associated with pleiotropic fitness costs in stress-free environments, we observed that accumulation of resistance mechanisms was accompanied by a reduction in overall fitness costs. We suggest that antagonistic epistasis may be a driving mechanism that enables populations to more readily adapt in novel environments. These findings highlight the potential for sequences of xenobiotics to facilitate the rapid evolution of multiple-drug and -pesticide resistance, as well as the potential for epistatic interactions between adaptive mutations to facilitate evolutionary rescue in rapidly changing environments.
authors.affiliation: IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria mato.lagator@gmail.com.
authors.forename: Mato
authors.initials: M
authors.lastname: Lagator
authors.affiliation: School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK.
authors.forename: Nick
authors.initials: N
authors.lastname: Colegrave
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Neve
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D016825:Chlamydomonas reinhardtii / Q000235:genetics; D004843:Epistasis, Genetic; D056084:Genetic Fitness; D053209:Herbicide Resistance / Q000235:genetics; D006540:Herbicides / Q000633:toxicity; D008957:Models, Genetic; D012641:Selection, Genetic
chemical_list: D006540:Herbicides
keywords: adaptation; environmental change; epistasis; evolutionary rescue; pleiotropy; xenobiotics