title: Adaptive value of phenological traits in stressful environments: predictions based on seed production and laboratory natural selection.
abstract: Phenological traits often show variation within and among natural populations of annual plants. Nevertheless, the adaptive value of post-anthesis traits is seldom tested. In this study, we estimated the adaptive values of pre- and post-anthesis traits in two stressful environments (water stress and interspecific competition), using the selfing annual species Arabidopsis thaliana. By estimating seed production and by performing laboratory natural selection (LNS), we assessed the strength and nature (directional, disruptive and stabilizing) of selection acting on phenological traits in A. thaliana under the two tested stress conditions, each with four intensities. Both the type of stress and its intensity affected the strength and nature of selection, as did genetic constraints among phenological traits. Under water stress, both experimental approaches demonstrated directional selection for a shorter life cycle, although bolting time imposes a genetic constraint on the length of the interval between bolting and anthesis. Under interspecific competition, results from the two experimental approaches showed discrepancies. Estimation of seed production predicted directional selection toward early pre-anthesis traits and long post-anthesis periods. In contrast, the LNS approach suggested neutrality for all phenological traits. This study opens questions on adaptation in complex natural environment where many selective pressures act simultaneously.
authors.affiliation: Laboratoire Génétique et Evolution des Populations Végétales, UMR CNRS 8198, Université des Sciences et Technologies de Lille - Lille 1, Villeneuve d'Ascq, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Brachi
authors.forename: Carla
authors.initials: C
authors.lastname: Aimé
authors.forename: Cédric
authors.initials: C
authors.lastname: Glorieux
authors.forename: Joel
authors.initials: J
authors.lastname: Cuguen
authors.forename: Fabrice
authors.initials: F
authors.lastname: Roux
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D019020:Directed Molecular Evolution / Q000379:methods*; D004777:Environment; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D005838:Genotype; D007753:Laboratories; D010507:Periodicity; D010641:Phenotype; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D013312:Stress, Physiological / Q000235:genetics*