PS 2-18 - A proposed unified framework for microbial community coalescence

Abstract: Ecologists have long investigated the mechanisms and processes associated with the causes and consequences of biological invasions. This wealth of literature stems primarily from macro-organisms that tend to disperse and invade foreign communities as single non-native species. Unlike macro-organisms, however, microbes are often dispersed as intact assemblages. The term community coalescence refers to the wholesale mixing of microbial communities, and it is likely the norm rather than an exception in microbial systems. From river confluences and herbivory to fecal microbiome transplants, community coalescence occurs in both natural and engineered systems. Primally considered through the lens of membership (e.g., source tracking of microbes), coalescence also has functional and evolutionary consequences in community ecology. To better understand the dynamics of community coalescence and multispecies invasion, we conducted a review of the literature through Web of Science focused primarily on the terms “community coalescence”, “whole community invasion”, and “engraftment”. Our results show that there has been a statistically significant and rapid increase in the study of community coalescence over the past 10 years across various sub-disciplines. To bring consilience and facilitate future study, we developed an integrative framework of community coalescence that can be interpreted in line with the unified theory of biological invasions. We begin by discussing commonalities and idiosyncrasies between the theoretical frameworks to align these two ecological processes. We then highlight various aspects of coalescence (i.e., abiotic mixing, community taxonomy and membership, functional and metabolic properties, and community phylogenetics and assembly) and describe the influence each component may have on the temporal dynamics of community mixing. Our integrative framework of community coalescence can be widely applied to diverse human interests (e.g., agriculture, wastewater treatment, clinical settings, and restoration ecology) and will guide future experimental work across systems.