Yale School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511;
Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210.
Proc Natl Acad Sci U S A. 2019 Apr 9;116(15):7371-7376. doi: 10.1073/pnas.1810767116. Epub 2019 Mar 6.
Microbes are thought to maintain diversity in plant communities by specializing on particular species, but it is not known whether microbes that specialize within species (i.e., on genotypes) affect diversity or dynamics in plant communities. Here we show that soil microbes can specialize at the within-population level in a wild plant species, and that such specialization could promote species diversity and seed dispersal in plant communities. In a shadehouse experiment in Panama, we found that seedlings of the native tree species, (Myristicaceae), had reduced performance in the soil microbial community of their maternal tree compared with in the soil microbial community of a nonmaternal tree from the same population. Performance differences were unrelated to soil nutrients or to colonization by mycorrhizal fungi, suggesting that highly specialized pathogens were the mechanism reducing seedling performance in maternal soils. We then constructed a simulation model to explore the ecological and evolutionary consequences of genotype-specific pathogens in multispecies plant communities. Model results indicated that genotype-specific pathogens promote plant species coexistence-albeit less strongly than species-specific pathogens-and are most effective at maintaining species richness when genetic diversity is relatively low. Simulations also revealed that genotype-specific pathogens select for increased seed dispersal relative to species-specific pathogens, potentially helping to create seed dispersal landscapes that allow pathogens to more effectively promote diversity. Combined, our results reveal that soil microbes can specialize within wild plant populations, affecting seedling performance near conspecific adults and influencing plant community dynamics on ecological and evolutionary time scales.
微生物被认为通过专门针对特定物种来维持植物群落的多样性，但尚不清楚专门针对物种内（即基因型）的微生物是否会影响植物群落的多样性或动态。在这里，我们表明，土壤微生物可以在野生植物物种的种群内专门化，并且这种专门化可以促进植物群落中的物种多样性和种子扩散。在巴拿马的一个遮荫温室实验中，我们发现，本地树种 （肉豆蔻科）的幼苗在其母树的土壤微生物群落中的表现不如来自同一种群的非母树的土壤微生物群落中的表现。性能差异与土壤养分或菌根真菌的定植无关，这表明高度专门化的病原体是降低母土中幼苗性能的机制。然后，我们构建了一个模拟模型来探索多物种植物群落中基因型特异性病原体的生态和进化后果。模型结果表明，基因型特异性病原体促进了植物物种共存——尽管不如物种特异性病原体强烈——并且在遗传多样性相对较低时最有效地维持物种丰富度。模拟还表明，与物种特异性病原体相比，基因型特异性病原体选择增加种子扩散，这可能有助于创造种子扩散景观，使病原体能够更有效地促进多样性。综合来看，我们的研究结果表明，土壤微生物可以在野生植物种群内专门化，影响同种成年植物附近的幼苗性能，并在生态和进化时间尺度上影响植物群落动态。
