Dynamics of an experimental microbial invasion
Dynamics of an experimental microbial invasion
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DOI：
10.1073/pnas.1505204112
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发表时间：
2015-09-15
影响因子：
11.1
通讯作者：
Hambright, K. David
中科院分区：
文献类型：
--
作者：
Acosta, Francisco;Zamor, Richard M.;Hambright, K. David
在过去的五十年里，物种入侵背后的生态动力学一直是大型生物研究的主要焦点。然而，我们仍然对单细胞生物入侵背后的过程知之甚少。为了扩大我们对微生物入侵的了解，我们研究了繁殖体压力，营养供应和生物抗性在淡水入侵植物Prymnesium parvum入侵成功中的作用，使用包含天然淡水微生物组合的微观世界。微宇宙进行析因设计，具有两个水平的营养诱导的多样性和三个水平的繁殖体压力，并培养7 d，在此期间，P. parvum密度和微生物群落组成进行了跟踪。成功的入侵发生在接受高繁殖压力的小宇宙，而营养物质或社区多样性在入侵成功中没有发挥作用。与入侵不成功的社区相比，入侵社区的组成发生了明显的变化。成功入侵的微生物群落增加了真菌和纤毛虫的丰度，减少了硅藻和尾虫的丰度。许多这些变化反映了微生物群落的变化，在源系统中的自然P. parvum水华期间检测到。繁殖体压力的这一作用与美国南部以热带雨林为主的P. parvum特别相关，因为该物种可以形成大的、持续的水华，从而为下游站点产生强烈的繁殖体压力。人类的影响和全球气候变化目前正在美国南部大部分淡水系统中引起广泛的环境变化，这可能有助于P. parvum的建立，并且当加上强大的繁殖压力时，可能会使更多的系统处于入侵的风险之中。
The ecological dynamics underlying species invasions have been a major focus of research in macroorganisms for the last five decades. However, we still know little about the processes behind invasion by unicellular organisms. To expand our knowledge of microbial invasions, we studied the roles of propagule pressure, nutrient supply, and biotic resistance in the invasion success of a freshwater invasive alga, Prymnesium parvum, using microcosms containing natural freshwater microbial assemblages. Microcosms were subjected to a factorial design with two levels of nutrient-induced diversity and three levels of propagule pressure, and incubated for 7 d, during which P. parvum densities and microbial community composition were tracked. Successful invasion occurred in microcosms receiving high propagule pressure whereas nutrients or community diversity played no role in invasion success. Invaded communities experienced distinctive changes in composition compared with communities where the invasion was unsuccessful. Successfully invaded microbial communities had an increased abundance of fungi and ciliates, and decreased abundances of diatoms and cercozoans. Many of these changes mirrored the microbial community changes detected during a natural P. parvum bloom in the source system. This role of propagule pressure is particularly relevant for P. parvum in the reservoir-dominated southern United States because this species can form large, sustained blooms that can generate intense propagule pressures for downstream sites. Human impact and global climate change are currently causing widespread environmental changes in most southern US freshwater systems that may facilitate P. parvum establishment and, when coupled with strong propagule pressure, could put many more systems at risk for invasion.