Community metabarcoding reveals the relative role of environmental filtering and dispersal in metacommunity dynamics of soil microarthropods across a mosaic of montane forests

Abstract

Disentangling the relative role of environmental filtering and dispersal limitation in driving metacommunity structure across mountainous regions remains challenging, as the way we quantify spatial connectivity in topographically and environmentally heterogeneous landscapes can influence our perception of which process predominates. More empirical datasets are required to account for taxon- and context-dependency but relevant research is often compromised by coarse taxonomic resolution. We here employed haplotype-level community DNA metabarcoding, enabled by stringent filtering of Amplicon Sequence Variants (ASVs), to characterize metacommunity structure of soil microarthropod assemblages across a mosaic of five forest habitats on the Troodos mountain range in Cyprus. We found similar β diversity patterns at ASV and species (OTU, Operational Taxonomic Unit) levels, which pointed to a primary role of habitat filtering resulting in the existence of largely distinct metacommunities linked to different forest types. Within-habitat turnover was correlated to topoclimatic heterogeneity, again emphasizing the role of environmental filtering. However, when integrating landscape matrix information for the highly fragmented Golden Oak habitat, we also detected a major role of dispersal limitation imposed by patch connectivity, indicating that stochastic and niche-based processes synergistically govern community assembly. Alpha diversity patterns varied between ASV and OTU levels, with OTU richness decreasing with elevation and ASV richness following a longitudinal gradient, potentially reflecting a decline of genetic diversity eastwards due to historical pressures. Our study demonstrates the utility of haplotype-level community metabarcoding for characterising metacommunity structure of complex assemblages and improving our understanding of biodiversity dynamics across mountainous landscapes worldwide.

Mountain soil food webs shaped by the interplay between habitat and pedoclimatic conditions

“…But even at the local scale of a few meters, variable abiotic conditions, including microclimate and soil physico-chemical properties, along with stochastic processes, can lead to pronounced differences in soil communities (Ramirez et al 2014;O'Brien et al2016;Zinger et al 2019). The structure of the vegetation within an habitat or its taxonomy or functional composition can also affect the abundance and diversity of different soil taxa or trophic groups (Noguerales et al 2021;Calderón-Sanou et al 2022;Ganault et al 2022). Effectively disentangling the effects of spatial, environmental and biotic processes necessitates a sampling design that encompasses multiple spatial scales, ranging from the heterogeneity between habitats to small-scale soil variations.…”