Experimental Studies Of Dispersal Limitation For Microorganism In Linfen Area

The formation and maintenance mechanism of biodiversity is one of the core issues in ecological research.Dispersal restriction has attracted more and more attention.At present,there is a great controversy on whether and to what extent microbial community construction is affected by dispersal restriction.In order to solve these problems,this study focused on the dispersal limitation of local microbial community in water.The water samples of Xinshui River,Longci,Fenhe,Qinhe,Quting reservoir and Huihe in Linfen City were collected.The physical and chemical properties of different water bodies and the diversity of microbial community were detected.The water bodies with different environment and microbial composition were screened out,and the common garden experiment and reciprocal transplant experiment were carried out to control the air microbial migration rate in the process.Microbial diversity of water bodies was obtained by Illumina miseq high throughput sequencing technology.on the one hand,to observe how migration rate affects the maintenance of community diversity and species composition,and to judge whether the community construction is affected by diffusion restriction under the condition of natural migration.On the other hand,it is necessary to observe whether the structure of these communities shows the composition change determined by the environment(environmental filtering signal),how much the original structure is maintained(historical influence),and the structural divergence between repeated microcosms(drift influence).Based on these results,we discuss the interaction of environmental filtration,drift and dispersal in the process of local community construction,and under what circumstances the community structure is prone to show historical contingency.The results are as follows:(1)Six water bodies in Linfen area were investigated: Among them,the dissolved oxygen(DO)of Longci sample was the highest(8.3 mg/L),and that of Fenhe sample was the lowest(6.6 mg/L).The species number of Longci water sample was significantly higher than that of Fenhe water sample,and the Chao 1 index of Longci water sample was significantly higher than that of Fenhe water sample,The species in Longci was the most(1489),while that in Fenhe was the least(843);The Shannon index and Simpson index of Fenhe were the smallest,which were 5.877 and 0.904,respectively;the Chao 1 index of Longci was the largest(1633.264),and the Chao1 index of Fenhe was the smallest(937.759);the diversity of Longci were high.(2)Based on the common garden experiment,the experimental results show that:With the increase of the migration rate of “local area” species pool,the community diversity of Fenhe microcosm continued to increase cultured for a long time(60 days),and the number of OTUs cultured for a long time was greater than that in the “local area” species pool,indicating that the community construction was affected by the diffusion limitation in the case of natural migration.The number of OTUs in Fenhe microcosm samples was larger than that in Longci microcosm when the migration rate of species pool in “local area” remained unchanged,no matter in a short time(13 days)or a long time(60 days),indicating that the composition of artificially diffused bacterial community mainly depends on the source community,and the local environment has a certain regulatory role.The community history and the distribution of groups in the community are important for the population,The effect of short-term environmental factors is secondary.Meanwhile,the experiment showed that Fenhe microcosm cultured for 13 days,Longci microcosm cultured for 60 days,Longci microcosm cultured for 13 days,Longci microcosm cultured for 60 days,Longci microcosm cultured for13 days,and Fenhe microcosm cultured for 60 days had great drift effect.(3)The experimental results show that: The species diversity of Fenhe-Longci microcosm cultured for 13 days and Longci-Fenhe microcosm cultured for 60 days increased with the increase of the migration rate of the species pool.Both of them were affected by the diffusion restriction.Fenhe-Fenhe and Fenhe-Longci microcosm cultured for 13 days were greatly affected by the environmental filtration in the process of constructing.Without adding species pool,Fenhe-Fenhe microcosm cultured for 13 days and Fenhe microcosm,Longci-Longci microcosm and Fenhe-Longci microcosm cultured for 60 days were cultured.Adding 1 m L species pool,Longci microcosm cultured for 13 days and Longci-Fenhe microcosm cultured for 60 days,the community was affected by drift.In conclusion,bacterial community construction is affected by diffusion limitation,environmental selection and drift,that is,bacterial community construction mechanism is controlled by deterministic process and stochastic process.