Physics of Living Systems, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
Nat Ecol Evol. 2020 Mar;4(3):376-383. doi: 10.1038/s41559-020-1099-4. Epub 2020 Feb 10.
Organisms-especially microbes-tend to live together in ecosystems. While some of these ecosystems are very biodiverse, others are not, and while some are very stable over time, others undergo strong temporal fluctuations. Despite a long history of research and a plethora of data, it is not fully understood what determines the biodiversity and stability of ecosystems. Theory and experiments suggest a connection between species interaction, biodiversity and the stability of ecosystems, where an increase in ecosystem stability with biodiversity could be observed in several cases. However, what causes these connections remains unclear. Here, we show in microbial ecosystems in the laboratory that the concentrations of available nutrients can set the strength of interactions between bacteria. High nutrient concentrations allowed the bacteria to strongly alter the chemical environment, causing on average more negative interactions between species. These stronger interactions excluded more species from the community, resulting in a loss of biodiversity. At the same time, the stronger interactions also decreased the stability of the microbial communities, providing a mechanistic link between species interaction, biodiversity and stability in microbial ecosystems.
生物——尤其是微生物——往往生活在生态系统中。虽然有些生态系统具有很高的生物多样性，而有些则不然，有些生态系统随着时间的推移非常稳定，而有些则经历强烈的时间波动。尽管长期以来进行了大量的研究并积累了大量的数据，但仍不完全清楚是什么决定了生态系统的生物多样性和稳定性。理论和实验表明，物种相互作用、生物多样性和生态系统稳定性之间存在联系，在某些情况下可以观察到生态系统稳定性随生物多样性的增加而增加。然而，导致这些联系的原因尚不清楚。在这里，我们在实验室的微生物生态系统中表明，可用营养物的浓度可以设定细菌之间相互作用的强度。高营养浓度使细菌能够强烈改变化学环境，导致物种之间的平均相互作用更负。这些更强的相互作用将更多的物种排除在群落之外，导致生物多样性的丧失。同时，更强的相互作用也降低了微生物群落的稳定性，为微生物生态系统中物种相互作用、生物多样性和稳定性之间提供了一种机制联系。
