Drift dynamics in microbial communities and the effective community size

Sloan, W. T. , Nnaji, C. F., Lunn, M., Curtis, T. P., Colloms, S. D., Couto, J. M., Pinto, A. J., Connelly, S. and Rosser, S. J. (2021) Drift dynamics in microbial communities and the effective community size. Environmental Microbiology, 23(5), pp. 2473-2483. (doi: 10.1111/1462-2920.15453) (PMID:33684262)

Abstract

The structure and diversity of all open microbial communities are shaped by individual births, deaths, speciation and immigration events; the precise timings of these events are unknowable and unpredictable. This randomness is manifest as ecological drift in the population dynamics, the importance of which has been a source of debate for decades. There are theoretical reasons to suppose that drift would be imperceptible in large microbial communities, but this is at odds with circumstantial evidence that effects can be seen even in huge, complex communities. To resolve this dichotomy we need to observe dynamics in simple systems where key parameters, like migration, birth and death rates can be directly measured. We monitored the dynamics in the abundance of two genetically modified strains of Escherichia coli, with tuneable growth characteristics, that were mixed and continually fed into 10 identical chemostats. We demonstrated that the effects of demographic (non‐environmental) stochasticity are very apparent in the dynamics. However, they do not conform to the most parsimonious and commonly applied mathematical models, where each stochastic event is independent. For these simple models to reproduce the observed dynamics we need to invoke an “effective community size”, which is smaller than the census community size.

• Item Type: Articles
• Additional Information: This research was funded by two UK, Engineering and Physical Sciences Research Council grants, EP/H009604/1 and EP/K038885/1, and by a Royal Academy of Engineering Chair in Emerging Technology for WTS.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Rosser, Professor Susan and Sloan, Professor William and Pinto, Dr Ameet and Connelly, Dr Stephanie and Couto, Dr Jillian
• Authors: Sloan, W. T., Nnaji, C. F., Lunn, M., Curtis, T. P., Colloms, S. D., Couto, J. M., Pinto, A. J., Connelly, S., and Rosser, S. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences; College of Science and Engineering > School of Engineering; College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Environmental Microbiology
• Publisher: Wiley
• ISSN: 1462-2912
• ISSN (Online): 1462-2920
• Published Online: 08 March 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Environmental Microbiology 23(5): 2473-2483
• Publisher Policy: Reproduced under a Creative Commons License

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
163046		Predicting the acclimatisation of microbial wastewater treatment communities as a function of the environment, random immigration, birth and death	William Sloan	Engineering and Physical Sciences Research Council (EPSRC)	EP/H009604/1	ENG - Infrastructure & Environment
190641		Synthetic Biology applications to Water Supply and Remediation	Steven Beaumont	Engineering and Physical Sciences Research Council (EPSRC)	EP/K038885/1	Research and Innovation Services