DOI: 10.5061/dryad.vq83bk3sb
title: Multiple mutualism effects generate synergistic selection and strengthen fitness alignment in the interaction between legumes, rhizobia, and mycorrhizal fungi

description: Nearly all organisms participate in multiple mutualisms, and
 complementarity within these complex interactions can result in
 synergistic fitness effects. However, it remains largely untested how
 multiple mutualisms impact eco-evolutionary dynamics in interacting
 species. We tested how multiple microbial mutualists-- N-fixing bacteria
 and mycorrrhizal fungi-- affected selection and heritability of traits in
 their shared host plant (Medicago truncatula), as well as fitness
 alignment between partners. Our results demonstrate for the first time
 that multiple mutualisms synergistically affect selection and heritability
 of host traits and enhance fitness alignment between mutualists.
 Specifically, we found interaction with multiple microbial symbionts
 doubled the strength of natural selection on a plant architectural trait,
 resulted in 2-3-fold higher heritability of plant reproductive success,
 and more than doubled fitness alignment between N-fixing bacteria and
 plants. These findings show synergism generated by multiple mutualisms
 extends to key components of microevolutionary change, emphasizing the
 importance of multiple mutualism effects on evolutionary trajectories.
description: The details on data collection are available in the associated
 paper in <em>Ecology Letters</em>. In brief, 213 <i>M.
 truncatula</i> genotypes were grown in a factorial experiment with
 four microbial environments environments: no microbes (NM,NR), rhizobia
 alone (NM, R), mycorrhizal fungi alone (M, NR), and both microbes (R,M).
 We measured a plant fitness proxy (pod production), a rhizobia fitness
 proxy (nodule number), and several plant traits related to plant
 architecture (branch number) and investment (allocation to roots vs shoot
 biomass). 
description: The data are from 213 <i>M. truncatula</i> genotypes
 grown in four microbial environments environments: no microbes (NM,NR),
 rhizobia alone (NM, R), mycorrhizal fungi alone (M, NR), and both microbes
 (R,M).  For each <i>M. truncatula</i> genotype in each of the
 four microbial environments, we provide in this dataset the average number
 of pods produced, number of branches grown, and root investment vs shoot
 investment (root to shoot ratio) as well as number of nodules produced by
 rhizobia associating with that plant genotype (associated columns
 are mean_pod, mean_branch, mean_root2shoot, and mean_nodule
 respectively). We also provide the relativized versions of these metric
 that were used and described in the paper analyses (associated columns of
 plant_rel_fitness, rel_mean_ branch, rel_mean_root2shoot, and
 rhizo_rel_fitness , respectively). The remaining columns describe the
 treatments and are myco (= mycorrhizal treatment), rhizo (= rhizobia
 treatment), and line (= plant genotype). The line genotype codes match the
 Medicago hapmap project (http://www.medicagohapmap.org/). Note that NA
 indicates no data is available for that genotype-by-microbial environment
 combination; it happens most frequently in the nodulation related columns
 because in the treatments with no rhizobia (MNR and NMNR) nodulation is
 not possible.