Biodiversity acts as insurance of productivity of bacterial communities under abiotic perturbations

Abstract

Anthropogenic disturbances are detrimental to the functioning and stability of natural ecosystems. Critical ecosystem processes driven by microbial communities are subjected to these disturbances. Here, we examine the stabilizing role of bacterial diversity on community biomass in the presence of abiotic perturbations such as addition of heavy metals, NaCl and warming. Bacterial communities with a diversity gradient of 1-12 species were subjected to the different treatments, and community biomass (OD600) was measured after 24 h. We found that initial species richness and phylogenetic structure impact the biomass of communities. Under abiotic perturbations, the presence of tolerant species in community largely contributed in community biomass production. Bacterial diversity stabilized the biomass across the treatments, and differential response of bacterial species to different perturbations was the key reason behind these effects. The results suggest that biodiversity is crucial for maintaining the stability of ecosystem functioning and acts as ecological insurance under abiotic perturbations. Biodiversity in natural ecosystems may also uphold the ecosystem functioning under anthropogenic disturbance.

Figure 1

Relationship between coefficient of variation of community biomass (sqrtOD₆₀₀) and diversity ((a) species richness, (b) phylogenetic diversity and (c) mean pairwise distance). The coefficient of variation of biomass for each community was calculated on pooled data across the all treatments. N.S., not significant.

Figure 2

Effect of phylogenetic diversity on biomass (sqrtOD₆₀₀) of bacterial communities under different treatments: (a) control, (b) heavy metals, (c) NaCl and (d) warming. For clarity, P-value less than 0.00001 was given as zero.

Figure 3

Effect of presence of number of tolerant species on biomass (sqrtOD₆₀₀) of bacterial communities under different treatments: (a) heavy metals, (b) NaCl and (c) warming. For clarity, P-value less than 0.00001 was given as zero.

Figure 4

Linear model coefficients showing comparative contribution of species effects in community biomass: (a) control, (b) heavy metals, (c) NaCl and (d) warming. Positive values of coefficients show an above-average contribution of species identity to community biomass and negative values show a below-average contribution. Significant coefficients are marked with asterisks. A, Bacillus subtilis; B, Staphylococcus pasteuri; C, Bacillus megaterium; D, Stenotrophomonas sp.; E, Pseudomonas fluorescens; F, Acenetobacter junii; G, Ochrobactrum rhizosphaerae; H, Aurantimonas sp.; I, Agrobacterium sp.; J, Microbacterium sp.; K, Kocuria marina; L, Arthrobacter flavus.