Universal abundance fluctuations across microbial communities, tropical forests, and urban populations

Ashish B. George, James Patrick O'Dwyer

Research output: Contribution to journalArticlepeer-review


The growth of complex populations, such as microbial communities, forests, and cities, occurs over vastly different spatial and temporal scales. Although research in different fields has developed detailed, system-specific models to understand each individual system, a unified analysis of different complex populations is lacking; such an analysis could deepen our understanding of each system and facilitate cross-pollination of tools and insights across fields. Here, we use a shared framework to analyze time-series data of the human gut microbiome, tropical forest, and urban employment. We demonstrate that a single, three-parameter model of stochastic population dynamics can reproduce the empirical distributions of population abundances and fluctuations in all three datasets. The three parameters characterizing a species measure its mean abundance, deterministic stability, and stochasticity. Our analysis reveals that, despite the vast differences in scale, all three systems occupy a similar region of parameter space when time is measured in generations. In other words, although the fluctuations observed in these systems may appear different, this difference is primarily due to the different physical timescales associated with each system. Further, we show that the distribution of temporal abundance fluctuations is described by just two parameters and derive a two-parameter functional form for abundance fluctuations to improve risk estimation and forecasting.

Original languageEnglish (US)
Article numbere2215832120
JournalProceedings of the National Academy of Sciences
Issue number44
StatePublished - Oct 31 2023


  • urban dynamics
  • microbial ecology
  • fluctuations
  • stochastic population dynamics
  • science of cities

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Universal abundance fluctuations across microbial communities, tropical forests, and urban populations'. Together they form a unique fingerprint.

Cite this