Temperature-dependent trophic associations modulate soil bacterial communities along latitudinal gradients

TL;DR

This study explores how temperature and biotic interactions shape soil bacterial communities across different latitudes.

Contribution

The study reveals how temperature-dependent trophic interactions influence bacterial communities along latitudinal gradients.

Findings

Microbial diversity trends vary by kingdom, with bacteria decreasing, protists clumping, and T4-like viruses increasing with latitude.

Climatic effects on bacterial communities intensify sharply near 30°N to 32°N, while edaphic effects remain stable.

Protist–bacteria interactions follow a quadratic pattern, and virus–bacteria interactions are significant only at high latitudes.

Abstract

Understanding the environmental and biological mechanisms shaping latitudinal patterns in microbial diversity is challenging in the field of ecology. Although multiple hypotheses have been proposed to explain these patterns, a consensus has rarely been reached. Here, we conducted a large-scale field survey and microcosm experiments to investigate how environmental heterogeneity and putative trophic interactions (exerted by protist–bacteria associations and T4-like virus–bacteria associations) affect soil bacterial communities along a latitudinal gradient. We found that the microbial latitudinal diversity was kingdom dependent, showing decreasing, clumped, and increasing trends in bacteria, protists, and T4-like viruses, respectively. Climatic and edaphic drivers played predominant roles in structuring the bacterial communities; the intensity of the climatic effect increased sharply from 30°N to 32°N, whereas the intensity of the edaphic effect remained stable. Biotic associations were also essential in shaping the bacterial communities, with protist–bacteria associations showing a quadratic distribution, whereas virus–bacteria associations were significant only at high latitudes. The microcosm experiments further revealed that the temperature component, which is affiliated with climate conditions, is the primary regulator of trophic associations along the latitudinal gradient. Overall, our study highlights a previously underestimated mechanism of how the putative biotic interactions influence bacterial communities and their response to environmental gradients.

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