Abstract: Temporal environmental variations, whether periodic/seasonal or stochastic, are ubiquitous in nature. The mechanisms by which they influence the persistence and coexistence of ecological communities are the subject of extensive research, with particular attention devoted to the storage effect and relative nonlinearity, which can promote the coexistence of species in local communities.
The majority of research in this field concentrates on a single metric, the invasion growth rate (IGR) that reflects the mean growth rate of a species when it is rare. A positive IGR indicates that populations that become rare in certain circumstances have a tendency to rebound, while a negative IGR implies the opposite.
In a series of recent papers [1,2], we have demonstrated that while the invasion growth rate (IGR) provides a satisfactory binary classification, its numerical value does not necessarily correlate with the important features of persistence and coexistence, such as the likelihood of invasion, time to extinction, and more. In certain situations, particularly in fluctuating environments, an increase in the numerical value of IGR may even lead to a decrease in invasion chances and persistence times.
Our objective is to establish a more quantitative theory of persistence and coexistence that elucidates the factors influencing attributes such as the chance of invasion and persistence time while providing insight into the role each plays in persistence. Using various techniques from statistical physics and extensive numerical simulations, we have highlighted the importance of the variance of the growth rate [3] and quantified the contribution of the storage effect and other mechanisms as a function of the number of species, the number of temporal niches, and the characteristics of the environmental process, including correlation times and periodic vs. stochastic fluctuations [4-5].
Our results offer a comprehensive perspective on how temporal fluctuations affect the coexistence of communities, providing a better intuitive understanding of natural dynamics and some new tools for quantitative assessments of its features. This research suggests valuable insight for policymakers and ecologists alike, as it highlights the importance of considering multiple factors beyond IGR in assessing the persistence and coexistence of ecological communities in fluctuating environments.
