A framework for integrating microbial dispersal modes into soil ecosystem ecology

Abstract

Dispersal is a fundamental community assembly process that maintains soil microbial biodiversity across spatial and temporal scales, yet the impact of dispersal on ecosystem function is largely unpredictable. Dispersal is unique in that it contributes to both ecological and evolutionary processes and is shaped by both deterministic and stochastic forces. The ecosystem-level ramifications of dispersal outcomes are further compounded by microbial dormancy dynamics and environmental selection. Here we review the knowledge gaps and challenges that remain in defining how dispersal, environmental filtering, and microbial dormancy interact to influence the relationship between microbial community structure and function in soils. We propose the classification of microbial dispersal into three categories, through vegetative or active cells, through dormant cells, and through acellular dispersal, each with unique spatiotemporal dynamics and microbial trait associations. This conceptual framework should improve the integration of dispersal in defining soil microbial community structure-function relationships.

Keywords: Microbiology; Soil ecology; Soil science.

Graphical abstract

Figure 1

Microbial dispersal modes Dispersal affects microbial structure-function relationships in soils by distributing genes (i.e., potential ecological functions, which are represented here by blue/red DNA fragments) in three primary ways: through active or vegetative cell dispersal, through dormant cell dispersal, and through acellular dispersal. Dispersal can occur at different scales over space and time, and can be independent of environmental filtering and ecological constraints that structure organism-level rules of microbial community assembly. Long-range spatial migration is likely dominated by dormant (i.e., spore) dispersal through aeolian deposition, though active cells and viruses also constitute the air microbiome. Local dispersal over short time scales includes viral-mediated genetic transfer as well as uptake of free environmental DNA (eDNA) from soil necromass pools. Cellular dispersal over intermediate spatial scales can occur via fungal highways or vectors including soil arthropods. Over longer time scales, dormancy shapes population genetics by effecting evolutionary diversification processes