Divergent responses of abundant and rare archaeal taxa to spatial heterogeneity in coastal sandy soils

Archaea play essential roles in nutrient biogeochemical cycling, ecosystem stability, and the regulation of key ecological processes. Despite their significance, most research has focused on extreme, localized habitats, leaving a gap in our understanding of archaeal community structures across broader coastal ecosystems. In this study, we used high-throughput sequencing to investigate archaeal communities in 12 coastal sandy soil sites along a latitudinal gradient spanning over 2000 km in China. Our findings revealed that Bray-Curtis similarity was negatively correlated with geographical distance, particularly for abundant taxa. Mean annual temperature (MAT), total phosphorus (TP), and pH were identified as the primary drivers of variation in archaeal community composition. A positive correlation between α-diversity and latitude was observed exclusively in abundant taxa, with available phosphorus (AP) emerging as the most significant environmental predictor. Community assembly processes differed between taxa: deterministic factors predominated in rare taxa, while stochastic processes governed abundant taxa. Notably, stochasticity in abundant taxa and determinism in rare taxa exhibited a positive correlation with latitude. Community assembly of abundant taxa correlated significantly with pH, salinity, total sulfur (TS), total nitrogen (TN), mean annual precipitation (MAP), electrical conductivity (EC), ammonium nitrogen (NH₄⁺-N), and nitrate nitrogen (NO₃⁻-N), while rare taxa assembly was mainly linked to TN, total carbon (TC), MAT, MAP, and NO₃⁻-N. Co-occurrence network analyses revealed higher complexity in rare archaea but greater stability in abundant archaea. Latitude shaped these network patterns, with pH, TN, and organic carbon (OC) identified as the key driving factors. This study advances our understanding of archaeal biogeography and ecological adaptation across large-scale coastal ecosystems.