时间：2022年6月16日（星期四）14:30-16:30    

会议号：腾讯会议433 322 003

主办：资源与环境学院                    

报告人1：李爽 14:30-15:30

题目：单细胞分析揭示复杂微生物群落的稳定化

Stabilization of complex microbial communities revealed by single-cell analysis

摘要：按照意愿建立和改变一个微生物群落，并且将之维持数百个世代目前已被证明很有挑战性。尽管做出了最大努力，复杂微生物群落仍然表现得易受强烈随机变化的影响。目前人们构建和控制稳定的复杂微生物群落的能力有限。在此，我们提出一种循环传质的设计，可以使微生物群落长期稳定。五个局域微生物群落平行连续生长114个世代，并通过环路连接到一个区域池。我们变换了不同传质速率，使用了定量的高通量流式细胞术，以及针对整体群落和分选后亚群落的物种分类级测序，来监测微生物群落动态。增加传质速率降低了各局域之间和时间尺度上微生物群落构建的差异变化，不影响群落功能，克服了随机性变化，所有微生物群落表现出高度恒定性和增强的抵抗性。传质使五个局域微生物群落的结构同步化，特定细胞类型的持续存在十分突出。传质增加了细胞数量，因此降低了净生长速率μ’。某些细胞亚群没有表现出净生长μ’SCx，而是被区域池R拯救，从而仍然保留为微生物群落的一部分。传质的环路确保了那些本来会消亡的细胞群的生存，即使他们在所有局域微生物群落中都不生长，或生长慢于实际稀释速率D。基于集合群落理论的拯救效应是稳定化的主要机制，并且引导了同步化和亚群落的生存，无论细胞的生理特性包括生长速率的不同。

Building and changing a microbiome at will and maintaining it over hundreds of generations has so far proven challenging. Despite best efforts, complex microbiomes appear to be susceptible to large stochastic fluctuations. Current capabilities to assemble and control stable complex microbiomes are limited. Here, we propose a looped mass transfer design that stabilizes microbiomes over long periods of time. Five local microbiomes were continuously grown in parallel for over 114 generations and connected by a loop to a regional pool. Mass transfer rates were altered and microbiome dynamics were monitored using quantitative high-throughput flow cytometry and taxonomic sequencing of whole communities and sorted subcommunities. Increased mass transfer rates reduced local and temporal variation in microbiome assembly, did not affect functions, and overcame stochasticity, with all microbiomes exhibiting high constancy and increasing resistance. Mass transfer synchronized the structures of the five local microbiomes and nestedness of certain cell types was eminent. Mass transfer increased cell number and thus decreased net growth rates μ’. Subsets of cells that did not show net growth μ’SCx were rescued by the regional pool R and thus remained part of the microbiome. The loop in mass transfer ensured the survival of cells that would otherwise go extinct, even if they did not grow in all local microbiomes or grew more slowly than the actual dilution rate D would allow. The rescue effect, known from metacommunity theory, was the main stabilizing mechanism leading to synchrony and survival of subcommunities, despite differences in cell physiological properties, including growth rates.

报告人2：乔秀娟 15:30-16:30  

题目：中国森林群落结构的纬度梯度格局

The latitudinal pattern of forest community structures in China

摘要：基于中国东部从南到北纵贯30个纬度、涵盖全部典型森林类型的纬度梯度森林样带，系统研究了中国东部森林种-面积关系的地理格局、驱动因素及其形成机制，结果发现中国森林群落种-面积关系存在明显的区域分异，支持种-能量关系理论；种-多度分布及其对种-面积关系的影响存在显著的纬度梯度格局，即随机过程在群落构建中的重要性存在一个纬度梯度。为了进一步鉴定森林群落中的基础物种及其对群落结构的影响，申请人筛选了中国森林监测网络内的12个大型监测样地内的基础物种，并研究了基础物种与其他物种的关系，结果发现基础物种的数目存在着显著的纬度梯度格局，表现为温带地区群落中基础物种多而热带群落中少；然而，基础物种对群落内其他物种多样性的影响却不存在显著的纬度梯度格局，表明只要有基础物种存在，就会对群落造成深刻的影响。该研究有助于改善和扩展生物多样性保护意识，为推动在生态系统完整性层次上开展生物多样性保护行动提供了重要的科学依据和理论支持。

We explored the spatial patterns of species-area relationships (SAR) in forests in China by investigating numbers of species by life form group in 32 nested plots from 12 mountains. The slopes of the power law SAR decreased with increasing latitude for all life forms except herbaceous plants, and also decreased with increasing altitude for all life forms but not for shrubs. Actual evapotranspiration affected SAR significantly, but this effect varied significantly among life forms, indicating there are significant geographical patterns of SAR for China’s forests, which is primarily controlled by energy availability. We also explored the effects of spatial distribution and unevenness of abundance on SARs by comparing the empirical and simulated SARs. Both aggregation and unevenness affected the shape of SARs significantly. We used species abundance distribution (SAD) data, and fitted a non-neutral model of community assembly to these SADs. We found a less even abundance distribution and a likely increase in the strength of environmental filtering in regions further from the tropics and with decreasing temperatures. Our results suggested a latitudinal gradient in tree community assembly process in Chinese forests, in which deviations from neutrality increase with latitude. Then we used statistical criteria––outliers from size-frequency distributions and scale-dependent negative effects on alpha diversity and positive effects on beta diversity––to identify candidate foundation woody plant species in 12 large forestdynamics plots spanning 26 degrees of latitude in China.candidate foundation species were more common in temperate forests than in tropical forests, likely reflecting lower tree species diversity and a greater importance of nontrophic and niche effects in the temperate zone. Foundation species effects on alpha  diversity were invariant with spatial grain, but foundation species effects on beta diversity increased with increasing spatial grain. These results suggested it may be possible to use statistical criteria to identify, manage, and protect foundation forest species before they are no longer functionally relevant in forests around the world.