Adaptation of phoD-harboring bacteria to broader environmental gradients at high elevations than at low elevations in the Shennongjia primeval forest

Abstract

Disentangling responses of phoD-harboring bacteria to environmental factors in different habitats, crucial for understanding the ecosystem’s potential for organic phosphorus mineralization and plant productivity, is an important but poorly investigated subject. Using MiSeq sequencing and multiple statistical analyses, we investigated activity, abundance, taxonomic and phylogenetic diversity of phoD-harboring bacteria at low (<1500 m) and high (>1500 m) elevations in the Shennongjia primeval forest. We found significant difference in phoD gene abundance and no significant divergence in alkaline phosphomonoesterase activity between low elevations and high elevations. Soil phoD-harboring bacteria showed stronger phylogenetic signals and broader environmental thresholds at high elevations than at low elevations based on threshold indicator taxa analysis, Blomberg’s K statistic, and Fritz-Purvis D-test. In addition, phoD-harboring bacteria showed closer phylogenetic clustering at high elevations than at low elevations. Null model reflected that community assembly at low elevations was determined by both deterministic and stochastic processes, and community assembly at high elevations was mainly determined by stochastic processes. To our knowledge, this study first reports that phoD-harboring bacteria are less environmentally constrained and have stronger environmental adaptation at high elevations than at low elevations. Our findings expand knowledge of the diversity maintenance of phoD-harboring bacteria at low and high elevations, and might offer the prediction of potential changes in organic phosphorus mineralization in the Shennongjia primeval forest.