Disentangling metacommunity processes using multiple metrics in space and time

Abstract

Metacommunity ecology has focused on using observational and analytical approaches to disentangle the role of critical assembly processes, such as dispersal limitation and environmental filtering. Many methods have been proposed for this purpose, most notably multivariate analyses of species abundance and its association with variation in spatial and environmental conditions. These approaches tend to focus on few emergent properties of metacommunities and have largely ignored temporal community dynamics. By doing so, these are limited in their ability to differentiate metacommunity dynamics. Here, we develop a 'virtual ecologist' approach to evaluate critical metacommunity assembly processes based on a number of summary statistics of community structure across space and time. Specifically, we first simulate metacommunities emphasizing three main processes that underlie metacommunity dynamics (density-independent responses to abiotic conditions, density-dependent biotic interactions, and dispersal). We then calculate a number of commonly used summary statistics of community structure in space and time, and use random forests to evaluate their utility for understanding the strength of these three processes. We found that: (i) time series are necessary to disentangle metacommunity processes, (ii) each of the three studied processes is distinguished with different descriptors, (iii) each summary statistic is differently sensitive to temporal and spatial sampling effort. Some of the most useful statistics include the coefficient of variation of abundances through time and metrics that incorporate variation in the relative abundances (evenness) of species. Surprisingly, we found that when we only used a single snapshot of community variation in space, the most commonly used approaches based on variation partitioning were largely uninformative regarding assembly processes, particularly, variation in dispersal. We conclude that a combination of methods and summary statistics will be necessary to understand the processes that underlie metacommunity assembly through space and time.

The Internal Structure of Metacommunities

“…Finally, it is increasingly clear that temporal dynamics of community change in metacommunities can provide critical insights about the mechanisms that drive metacommunity patterns (e.g. Jabot et al 2020, Blanchard et al 2020, Guzman et al 2021). We imagine future work on the internal structure of metacommunities as being very amenable to incorporating temporal changes (see for example, Ovaiskainen et al 2017 for an initial step in this direction).…”

“…mean) metacommunity properties. Recent efforts have used several of these global metrics to dissect the relative importance of different major classes of metacommunity processes (Ovaskainen et al 2019, Guzman et al 2021. While these approaches provide insights into the processes that drive species distributions and determine their levels of interaction within metacommunities, they only characterize global (general) attributes across the entire metacommunity, which we consider to be the external structure of metacommunities.…”

The internal structure of metacommunities

“…Finally, it is increasingly clear that temporal dynamics of community change in metacommunities can provide critical insights about the mechanisms that drive metacommunity patterns (Blanchard et al 2020, Jabot et al 2020, Guzman et al 2021). We imagine future work on the internal structure of metacommunities as being very amenable to incorporating temporal changes (Ovaskainen et al 2017 for an initial step in this direction).…”

“…mean) metacommunity properties. Recent efforts have used several of these global metrics to dissect the relative importance of different major classes of metacommunity processes (Ovaskainen et al 2019, Guzman et al 2021). While these approaches provide insights into the processes that drive species distributions and determine their levels of interaction within metacommunities, they only characterize global (general) attributes across the entire metacommunity, which we consider to be the external structure of metacommunities.…”

Dinámica de comunidades vegetales en el valle semiárido de Zapotitlán, Puebla: un enfoque de metacomunidades y ecología de las invasiones

“…El nivel de metacomunidad permite integrar dinámicas locales y regionales, así como evaluar procesos que estarían actuando en el ensamble y dinámica de las comunidades locales, tales como la limitación de la dispersión, filtros ambientales e interacciones bióticas , Guzmán et al 2020. Debido a que generalmente las comunidades locales no se estructuran de manera independiente de los procesos que se llevan a cabo a escalas regionales (Mouquet y Loreau 2003, Leibold et al 2017, es necesario considerar el estudio de comunidades locales dentro de una metacomunidad, ya que probablemente los procesos que se llevan a cabo a estas dos escalas espaciales darán diferentes dinámicas que pueden alterar de manera directa o indirecta la diversidad local de especies , Shanafelt et al 2015;…”