亚热带水库浮游细菌广布种与狭布种季节动态与进化特征

Seasonal dynamics and evolutionary characteristics of generalist and specialist bacteria in a subtropical reservoir

摘要

水库作为重要的饮用水源地,其水生态系统的健康至关重要.以福建省某水源水库为研究对象,分析了水库拉氏尖头藻( Raphidiopsis raciborskii)水华季节演替过程中浮游细菌广布种和狭布种多样性、群落构建和进化特征.结果表明,尖头藻水华在水库中具有明显的季节性变化,细胞密度从春季逐步上升,夏季达到峰值(3.5×10⁸ L^-1,占浮游植物总量的90%以上),秋季仍维持高丰度,直至冬季逐渐消退.基于16S rRNA基因的高通量测序,检测到水库中浮游细菌的主要类群为放线菌门(Actinobacteriota)、变形菌门(Proteobacteria)和疣微菌门(Verrucomicrobiota).不同季节中,夏季细菌群落的物种丰富度最高,而冬季则表现出最高的Shannon多样性,随机森林结果表明尖头藻丰度显著影响了水库广布种和狭布种细菌群落的α及β多样性.广布种在各季节中均占据优势,其群落构建受到确定性过程的主导,水温和营养盐显著影响细菌群落的季节动态.广布种表现出较高的扩散能力和环境适应性,尤其在夏秋季节达到最高多样性.而狭布种主要局限于特定季节,尤其在冬季和夏季丰富度较高,表现出较强的季节演替现象.广布种细菌的物种分化率较高,灭绝率较低,具有较强的生态扩展潜力.狭布种则表现出较高的物种灭绝率,但具有向广布种转化的潜力,尤其在春夏季节物种多样性潜力显著提升.

Abstract

As a critical drinking water source, the health of reservoir ecosystems is of paramount importance. This study focuses on a subtropical reservoir in Fujian Province, analyzing the diversity, community assembly, and evolutionary characteristics of generalist and specialist planktonic bacteria during the seasonal succession of Raphidiopsis raciborskii blooms. The results revealed a clear seasonal pattern in R. raciborskii blooms, with cell density increasing from spring, peaking in summer (3.5×10 ⁸ L ^-1, accounting for over 90% of total phytoplankton biomass), and remaining high in autumn before gradually declining in winter. High-throughput sequencing of the 16S rRNA gene identified Actinobacteriota, Proteobacteria, and Verrucomicrobiota as the dominant bacterial phyla. Bacterial species richness was highest in summer, while Shannon diversity peaked in winter. Generalist species dominated across all seasons, with their community assembly driven by deterministic processes, significantly influenced by temperature and nutrient levels. These species exhibited high dispersal capacity and environmental adaptability, with peak diversity in summer and autumn. In contrast, specialist species were restricted to specific seasons, showing higher abundance in winter and summer, and displayed pronounced seasonal succession. Generalist species had higher speciation rates and lower extinction rates, indicating strong ecological expansion potential. Specialist species exhibited higher extinction rates but showed potential to transition into widespread species, particularly in spring and summer when their diversity potential increased.

关键词

尖头藻 / 浮游细菌 / 广布种 / 狭布种 / 群落构建

Key words

Raphidiopsis raciborskii / bacterioplankton / generalist / specialist / community assembly

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基金资助

浙江省自然科学基金(LMS26C030003)

国家自然科学基金(32371634)

福建省环保科技计划项目(2023R009)

上海市生态环境局科学项目(沪环科[2024]第9号)