Presentation Information
[POS-43]Relationships between species diversity and the number of alternative stable states: Energy landscape analysis approach
*Gen Iwashita1, Masato Yamamichi1 (1. National Institution of Genetics (Japan))
Keywords:
Alternative stable state,Species interaction,Energy landscape
Understanding the number of alternative stable states (ASSs) in community dynamics is crucial in ecology. This is because, with ASSs, community dynamics are influenced by the initial conditions as well as the order of species assembly, regime shifts may occur, and it becomes difficult to predict future community dynamics.
Species diversity (the number of species) in communities is known to affect the number of ASSs in community dynamics. Previous theoretical studies investigated the relationship between species diversity and the number of ASSs, but few studies examined how the characteristics of species interactions affect the relationship. One of the reasons for this is the numerical computation time: to study the number of ASSs, researchers often conducted numerical simulations of ordinary differential equations (ODEs) and counted the number of ASSs after a sufficiently long simulation time for various initial conditions. Because the number of initial conditions increases explosively as the number of species increases, it was practically difficult to explore the diversity-ASS relationship in detail.
In this study, we propose a new method to numerically estimate the number of ASSs within a realistic computational time by combining a stochastic model of community assembly with energy landscape analysis. Unlike the ODE approach, this method can be used to count the number of ASSs by only calculating the stable distribution in the stochastic assembly process. Using this method, we investigated how the relationship between the number of species and the number of ASSs varies with the strength of species interactions and topology of species interaction networks. We found that the mean strength of interspecies interactions (negative or positive) has a strong influence on the relationship between the number of species and the number of ASSs.
Species diversity (the number of species) in communities is known to affect the number of ASSs in community dynamics. Previous theoretical studies investigated the relationship between species diversity and the number of ASSs, but few studies examined how the characteristics of species interactions affect the relationship. One of the reasons for this is the numerical computation time: to study the number of ASSs, researchers often conducted numerical simulations of ordinary differential equations (ODEs) and counted the number of ASSs after a sufficiently long simulation time for various initial conditions. Because the number of initial conditions increases explosively as the number of species increases, it was practically difficult to explore the diversity-ASS relationship in detail.
In this study, we propose a new method to numerically estimate the number of ASSs within a realistic computational time by combining a stochastic model of community assembly with energy landscape analysis. Unlike the ODE approach, this method can be used to count the number of ASSs by only calculating the stable distribution in the stochastic assembly process. Using this method, we investigated how the relationship between the number of species and the number of ASSs varies with the strength of species interactions and topology of species interaction networks. We found that the mean strength of interspecies interactions (negative or positive) has a strong influence on the relationship between the number of species and the number of ASSs.