PT - JOURNAL ARTICLE AU - Xuyue Yang AU - Martin Lascoux AU - Sylvain Glémin TI - Competitive ability of a tetraploid selfing species (<em>Capsella bursa-pastoris</em>) across its expansion range and comparison with its sister species AID - 10.1101/214866 DP - 2017 Jan 01 TA - bioRxiv PG - 214866 4099 - http://biorxiv.org/content/early/2017/11/06/214866.short 4100 - http://biorxiv.org/content/early/2017/11/06/214866.full AB - Self-fertilization is often associated with ecological traits corresponding to the ruderal strategy in Grime’s CSR classification. Consequently, selfers are expected to be less competitive than outcrossers, either because of a colonization/competition trade-off or because of the deleterious genetic effects of selfing. Range expansion could reduce further competitive ability while polyploidy could mitigate the effects of selfing. Although suggested by meta-analyses, these predictions have not been directly tested yet. We compared the competitive ability of four Capsella species differing by their mating system and ploidy level. We found that the two diploid selfing species (C. rubella and C. orientalis) were more sensitive to competition than the diploid outcrosser (C. grandiflora), and the tetraploid selfer (C. bursa-pastoris) was intermediate. Within C. bursa-pastoris, we also found that sensitivity to competition increased across range expansion. These results highlight the possible roles of ecological context and ploidy in the evolutionary trajectories of selfing species.