【作者】 李连伟；

【导师】 马占山； 张阿梅；

【作者基本信息】 昆明理工大学 ， 细胞生物学， 2016， 硕士

【摘要】 研究背景及意义：群落物种多样性的共存以及维持机制一直是生态学研究的核心问题。生态位理论和中性理论是目前用于解释群落物种多样性维持机制的经典理论。但是在微生物群落中,生态位理论无法提供足够的生态位来容纳如此多的物种,而中性理论不受此限制,更适合于研究微生物群落物种多样性的共存以及维持机制。到目前为止中性理论极少应用于微生物群落,尤其在人体微生物群落中的研究更是凤毛麟角。随着宏基因组测序技术的发展,对微生物群落的研究手段日趋成熟。而人体微生物的研究更与人体健康、疾病、医药卫生息息相关。有鉴于此,美国国立卫生研究院(NIH)于2007年提出“人类微生物组计划(HMP)”,与此同时,欧盟委员会也提出了“人类肠道宏基因组学(MetaHIT)",开始大规模对人体微生物进行采样、测序、分析,积累了大量的数据。本文通过对人体微生物群落数据进行中性模型分析,旨在揭示人体微生物群落的结构以及物种共存机制。研究方法：(1)用中性理论模型拟合物种等级多度曲线。(2)用主方程推导出的中性理论模型拟合物种多度分布曲线。(3)在位点,部位,人体等不同水平检测中性理论。(4)用Ewens的抽样模型公式检测人体微生物群落是否符合中性理论。(5)用Etienne的抽样模型公式检测人体微生物群落是否符合中性理论。(6)用距离-衰减模型研究人体微生物的扩散限制。研究结果：(1)中性理论模型拟合物种等级多度曲线结果显示：皮肤的左右肘窝位点(Antecubital fossa)的样本符合中性理论比例最高,而女性生殖道(Mid vagina, Posterior fornix, Vaginal introitus)中微生物群落的等级多度曲线几乎不符合中性理论。(2)主方程推导出的中性理论模型拟合多度分布模型结果显示：该中性模型对高多度和低多度的的物种数预测并不理想,但是对多度处于中间的物种数预测较好。(3)部位水平和个体水平的中性理论检测结果显示,在叠加同一部位或个体的各个位点后,人体微生物群落并不符合中性理论。(4)分别用Ewens和Etienne的抽样公式检测中性理论,结果显示,两个抽样公式的计算结果没有显著差异,说明扩散限制并不影响人体微生物群落的形成。同时距离-衰减模型的结果也说明人体微生物群落不存在扩散限制。更多还原

【Abstract】 Background:A central goal of community ecology is to understand the forces that maintain species diversity within communities. Niche theory and neutral theory are main theory for explaining mechanism of maintain species diversity. But niche theory can not supply enough niches to contain so many diversity in microbial community, so neutral theory maybe more appropriate. So far, neutral theory rarely tested in microbial community, especially in human microbial community.16s rRNA sequencing has become the main method for researching microbial community as the development of sequencing technology. Also, human microbial community are closely related with heath, disease and medicines. The "human microbial project" (HMP) initiated by National Institutes of Health (NIH) and MetaHIT project financed by the European Commission have collected mass human microbial samples。 In this research, we use the HMP data to present a comprehensive test of the neutral theory with human microbiome data.Methods(1) Using neutral model test Species rank abundance.(2) Using neutral model from master equation test species abundance distribution.(3) Fitting neutral model in sites, locations and individuals level.(4) Using Ewens sampling formula for testing neutral theory(5) Using Etienne sampling formula for testing neutral theory.(6) Testing dispersal-limited by distance-decay model.Results:(1) About half samples of Right Antecubital fossa and Left Antecubital fossa satisfied the neutral model according to the species rank abundance and species abundance distribution. While samples from the Mid vagina, Posterior fornix and Vaginal introitus can not fit to neutral model.(2) Neutral model from master equation can predict median abundance species very well, but this model can not explain the coexist mechanism of dominance species and rare species.(3) When combined the microbial community of different sites in the same location or individual, Combined community can not fits neutral model.(4) Compared the result of Ewens sampling formula and Etienne sampling formula,. Both formulae made no differences in almost all human microbial communities we tested. This result according to distance-decay model show that there are no dispersal-limited in human microbial communities.更多还原