Abstract：
Microbial immigration is an ecological process in natural environments; however, the ecological trade-off mechanisms that govern the balance between species extinction and migration are still lacking. In this study, we investigated the mechanisms underlying the migration of diazotrophic communities from soil to leaves across six natural mangrove habitats in southern China. The results showed that the diazotrophic alpha and beta diversity exhibited significant regional and locational variations. The diazotrophic species pool gradually increased from the leaves to nonrhizosphere soil at each site, exhibiting a vertical distribution pattern. Mantel test analyses suggested that climate factors, particularly mean annual temperature, significantly influenced the structure of the diazotrophic community. The diazotrophic community assembly was mainly governed by dispersal limitation in soil and root samples, whereas dispersal limitation and ecological drift were dominant in leaves. Partial least squares path modeling revealed that the species pool and soil properties, particularly the oxidation-reduction potential and pH, were closely linked to the species-immigration ratio of diazotrophic communities. Our study provides novel insights for understanding the ecological trait diversity patterns and spread pathways of functional microbial communities between below- and aboveground habitats in natural ecosystems.IMPORTANCEEnvironmental selection plays key roles in microbial transmission. In this study, we have provided a comprehensive framework to elucidate the driving patterns of the ecological trade-offs in diazotrophic communities across large-scale mangrove habitats. Our research revealed that Bradyrhizobium japonicum, Marinobacterium lutimaris, and Agrobacterium tumefaciens were more abundant in root-associated soil than in leaves by internal and external pathways. The nonrhizospheric and rhizospheric soil samples harbored the most core amplicon sequence variants, indicating that these dominant diazotrophs could adapt to broader ecological niches. Correlation analysis indicated that the diversities of the diazotrophic community were regulated by biotic and abiotic factors. Furthermore, this study found a lower species immigration ratio in the soil than in the leaves. Both species pool and soil properties regulate the species-immigration mechanisms of the diazotrophic community. These results suggest that substantial species immigration is a widespread ecological process, leading to alterations in local community diversity across diverse host environments.
摘要：
微生物迁移是自然环境中的一个生态过程；然而，仍然缺乏控制物种灭绝和迁徙之间平衡的生态权衡机制。在这项研究中,我们调查了中国南方六个天然红树林栖息地中重氮营养群落从土壤到叶子迁移的潜在机制。结果表明，重氮营养α和β多样性表现出明显的区域和位置差异。在每个地点，重氮营养物种库从叶子到非根际土壤逐渐增加，呈现垂直分布格局。Mantel测试分析表明，气候因素，尤其是年平均气温，显著影响了重氮营养群落的结构。重氮营养群落的组装主要受土壤和根系样品中的扩散限制控制，而扩散限制和生态漂移在叶片中占主导地位。偏最小二乘路径建模揭示了物种库和土壤特性，特别是氧化还原电位和pH值，与重氮营养群落的物种移民比密切相关。我们的研究为理解自然生态系统中地下和地上栖息地之间的功能微生物群落的生态性状多样性模式和传播途径提供了新的见解。重要环境选择在微生物传播中起着关键作用。在这项研究中,我们提供了一个全面的框架，以阐明大规模红树林生境中重氮营养群落生态权衡的驱动模式。我们的研究表明日本根瘤菌，卢氏Marinobacteriumlutimaris,通过内部和外部途径，根癌农杆菌在与根相关的土壤中比在叶片中更丰富。非根际和根际土壤样品具有最核心的扩增子序列变体，表明这些优势重氮生物可以适应更广泛的生态位。相关分析表明，重氮营养群落的多样性受生物和非生物因素的调节。此外，这项研究发现，土壤中的物种移民率低于叶片中的物种移民率。物种库和土壤特性都调节了重氮营养群落的物种迁移机制。这些结果表明，大量物种移民是一个广泛的生态过程，导致不同宿主环境中当地社区多样性的变化。
