Abstract：
The cell size of phytoplankton is an important defining functional trait that can serve as a driver and sentinel of phytoplankton community structure and function. However, the study of the assembly patterns and drivers of phytoplankton metacommunities with different cell sizes has not been widely carried out. In this study, we systematically investigated the biodiversity patterns, drivers, and assembly processes of the three phytoplankton cell sizes (micro: 20-200 μm; nano: 2-20 μm; pico: 0.2-2 μm) in the Za\'gya Zangbo River from the source to the estuary using 18S rDNA amplicon sequencing. The results demonstrated that the alpha diversity and co-occurrence network complexity for all three sizes of phytoplankton increased to a peak downstream of the glacier sources and then decreased to the estuary. The nanophytoplankton subcommunity consistently had the highest alpha diversity and co-occurrence network complexity. On the other hand, total beta diversity followed a unimodal trend of decreasing and then increasing from source to estuary, and was dominated by species replacement components. In addition, deterministic processes driven mainly by physiochemical indices (PCIs) and biogenic elements (BGEs) dominated the assembly of micro- and nanophytoplankton subcommunities, whereas stochastic processes driven by geographical factors (GGFs) dominated the assembly of picophytoplankton subcommunities. The results explained the contradictions in previous studies of phytoplankton community assembly processes in highland aquatic ecosystems, elucidating the different contributions of deterministic and stochastic processes, and the complexity of compositional mechanisms in shaping the assembly of micro-, nano-, and picophytoplankton in this highland glacial river.
OBJECTIVE: The cell size of phytoplankton is a key life-history trait and key determinant, and phytoplankton of different cell sizes are differentially affected by ecological processes. However, the study of the assembly patterns and drivers of phytoplankton metacommunities with different cell sizes has not been widely carried out. We provide an in-depth analysis of phytoplankton community diversity across three cell sizes in the glacier-fed river, describing how the pattern of phytoplankton communities differs across cell sizes in response to geochemical gradients. The results show that the smaller phytoplankton (picophytoplankton) are relatively more influenced by dispersal-based stochastic processes, whereas larger ones (microphytoplankton and nanophytoplankton) are more structured by selection-based deterministic processes.
OBJECTIVE: The cell size of phytoplankton is a key life-history trait and key determinant, and phytoplankton of different cell sizes are differentially affected by ecological processes. However, the study of the assembly patterns and drivers of phytoplankton metacommunities with different cell sizes has not been widely carried out. We provide an in-depth analysis of phytoplankton community diversity across three cell sizes in the glacier-fed river, describing how the pattern of phytoplankton communities differs across cell sizes in response to geochemical gradients. The results show that the smaller phytoplankton (picophytoplankton) are relatively more influenced by dispersal-based stochastic processes, whereas larger ones (microphytoplankton and nanophytoplankton) are more structured by selection-based deterministic processes.
摘要：
浮游植物的细胞大小是重要的功能特征，可以作为浮游植物群落结构和功能的驱动因素和前哨。然而,对不同细胞大小的浮游植物元群落的组装模式和驱动因素的研究尚未广泛进行。在这项研究中,我们系统地研究了生物多样性模式，司机,以及使用18SrDNA扩增子测序从源头到河口的Za'gyaZangbo河中三种浮游植物细胞大小（微米：20-200μm；纳米：2-20μm；皮科：0.2-2μm）的组装过程。结果表明，所有三种浮游植物的α多样性和共现网络复杂性都增加到冰川源下游的峰值，然后下降到河口。纳米浮游生物亚群落始终具有最高的α多样性和共现网络复杂性。另一方面,总β多样性从源头到河口呈先下降后上升的单峰趋势，以物种替代成分为主。此外,主要由物理化学指数（PCI）和生物元素（BGE）驱动的确定性过程主导了微型和纳米浮游生物亚群落的组装，而由地理因素（GGFs）驱动的随机过程主导了浮游植物亚群落的组装。该结果解释了先前在高原水生生态系统中浮游植物群落组装过程研究中的矛盾。阐明确定性和随机过程的不同贡献，以及在塑造微观组件时组成机制的复杂性，纳米-，和这片高原冰川河中的浮游植物。
目的：浮游植物的细胞大小是关键的生活史特征和关键决定因素，不同细胞大小的浮游植物受到生态过程的不同影响。然而,对不同细胞大小的浮游植物元群落的组装模式和驱动因素的研究尚未广泛进行。我们对冰川河中三种细胞大小的浮游植物群落多样性进行了深入分析，描述浮游植物群落的模式如何在响应地球化学梯度的细胞大小上有所不同。结果表明，较小的浮游植物（picophytoplankton）受基于分散的随机过程的影响相对较大，而较大的（微浮游植物和纳米浮游植物）则由基于选择的确定性过程构成。
目的：浮游植物的细胞大小是关键的生活史特征和关键决定因素，不同细胞大小的浮游植物受到生态过程的不同影响。然而,对不同细胞大小的浮游植物元群落的组装模式和驱动因素的研究尚未广泛进行。我们对冰川河中三种细胞大小的浮游植物群落多样性进行了深入分析，描述浮游植物群落的模式如何在响应地球化学梯度的细胞大小上有所不同。结果表明，较小的浮游植物（picophytoplankton）受基于分散的随机过程的影响相对较大，而较大的（微浮游植物和纳米浮游植物）则由基于选择的确定性过程构成。
