Data from: Interspecific conflict and the evolution of ineffective rhizobia

Microbial symbionts exhibit broad genotypic variation in their fitness effects on hosts, leaving hosts vulnerable to costly partnerships. Interspecific conflict and partner‐maladaptation are frameworks to explain this variation, with different implications for mutualism stability. We investigated the mutualist service of nitrogen fixation in a metapopulation of root‐nodule forming Bradyrhizobium symbionts in Acmispon hosts. We uncovered Bradyrhizobium genotypes that provide negligible mutualist services to hosts and had superior in planta fitness during clonal infections, consistent with cheater strains that destabilise mutualisms. Interspecific conflict was also confirmed at the metapopulation level – by a significant negative association between the fitness benefits provided by Bradyrhizobium genotypes and their local genotype frequencies – indicating that selection favours cheating rhizobia. Legumes have mechanisms to defend against rhizobia that fail to fix sufficient nitrogen, but these data support predictions that rhizobia can subvert plant defenses and evolve to exploit hosts.Table_S1Table S1 Genotypes of Bradyrhizobium isolatesTable_S2Table S2 Table of all isolates included in analyses and associated accession numbers.Table_S3Table S3 Acmispon hosts and inoculation treatmentsTable_S4Table S4 Raw inoculation experiment dataFunding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: NSF DEB 1150278, NSF DEB1738028