In plant communities, diversity often increases productivity and functioning, but the specific underlying drivers are difficult to identify. Most ecological theories attribute positive diversity effects to complementary niches occupied by different species or genotypes. However, the specific nature of niche complementarity often remains unclear, including how it is expressed in terms of trait differences between plants. Here, we use a gene-centred approach to study positive diversity effects in mixtures of natural Arabidopsis thaliana genotypes. Using two orthogonal genetic mapping approaches, we find that between-plant allelic differences at the AtSUC8 locus are strongly associated with mixture overyielding. AtSUC8 encodes a proton-sucrose symporter and is expressed in root tissues. Genetic variation in AtSUC8 affects the biochemical activities of protein variants and natural variation at this locus is associated with different sensitivities of root growth to changes in substrate pH. We thus speculate that - in the particular case studied here - evolutionary divergence along an edaphic gradient resulted in the niche complementarity between genotypes that now drives overyielding in mixtures. Identifying genes important for ecosystem functioning may ultimately allow linking ecological processes to evolutionary drivers, help identify traits underlying positive diversity effects, and facilitate the development of high-performance crop variety mixtures.

在植物群落中，多样性通常会提高生产力和功能，但具体的潜在驱动因素很难确定。大多数生态理论将积极的多样性效应归因于不同物种或基因型占据的互补生态位。然而，生态位互补性的具体性质通常仍不清楚，包括它如何以植物之间的性状差异表达。在这里，我们使用以基因为中心的方法来研究天然拟南芥基因型混合物的积极多样性效应。使用两种正交遗传作图方法，我们发现AtSUC8基因座处的植物间等位基因差异与混合物高产密切相关。AtSUC8编码质子-蔗糖同向转运体并在根组织中表达。AtSUC8的遗传变异影响蛋白质变体的生化活性，并且该位点的自然变异与根生长对底物 pH 变化的不同敏感性有关。因此，我们推测 - 在此研究的特定案例中 - 沿着土壤梯度的进化分歧导致了基因型之间的生态位互补性，现在驱动了混合物的高产。识别对生态系统功能重要的基因最终可能会将生态过程与进化驱动因素联系起来，帮助识别积极多样性效应背后的性状，并促进高性能作物品种混合物的开发。