Lack of functional redundancy in the relationship between microbial diversity and ecosystem functioning

Abstract

Summary Biodiversity is declining world‐wide with detrimental effects on ecosystems. However, we lack a quantitative understanding of the shape of the relationship between microbial biodiversity and ecosystem function (BEF). This limits our understanding of how microbial diversity depletion can impact key functions for human well‐being, including pollutant detoxification. Three independent microcosm experiments were conducted to evaluate the direction (i.e. positive, negative or null) and the shape of the relationships between bacterial diversity and both broad (i.e. microbial respiration) and specialized (i.e. toxin degradation) functions in five Australian and two UK freshwater ecosystems using next‐generation sequencing platforms. Reduced bacterial diversity, even after accounting for biomass, caused a decrease in broad (i.e. cumulative microbial respiration) and specialized (biodegradation of two important toxins) functions in all cases. Unlike the positive but decelerating BEF relationship observed most frequently in plants and animals, most evaluated functional measurements were related to bacterial diversity in a non‐redundant fashion (e.g. exponentially and/or linearly). Synthesis. Our results suggest that there is a lack of functional redundancy in the relationship between bacterial diversity and ecosystem functioning; thus, the consequences of declining microbial diversity on ecosystem functioning and human welfare have likely been considerably underestimated.

Ecological drivers of soil microbial diversity and soil biological networks in the Southern Hemisphere

“…In particular, we fitted four different functions: linear, quadratic, cubic and logarithmic. Here, we consider a DAIC c > 2 threshold to differentiate between two substantially different models and then select the best of those models (Delgado-Baquerizo et al 2016b). The lower the AIC c index the better the model.…”

Geographic Impact on Genomic Divergence as Revealed by Comparison of Nine Citromicrobial Genomes

“…This emphasizes that traditional diversity studies, which classify sequences into operational taxonomic units based on the nucleotide sequence similarity, underestimate real environmental microbial information. The classification and diversity results based on environmental 16S rRNA could not link to in situ microbial functions (46,47).…”

Causes and consequences of soil bacterial rarity

“…Low abundance soil microbes are known to contain species with a high potential impact on various ecosystem functions (Delgado-Baquerizo et al 2016). Therefore, we examined whether the absence of some of the rare microbes may play a role in priming plant defences against insect herbivores.…”

“…This indicates that there is a high functional redundancy in soil microbial communities with respect to traits involved in general decomposition, but also that this redundancy is important for resistance to disturbance (Griffiths et al 2001b). In contrast to functional redundancy in general decomposition, several specific biogeochemical processes, such as denitrification and the degradation of pollutants have been found to be restricted to a narrow set of often rare species (Philippot et al 2013b, Delgado-Baquerizo et al 2016 (Fig. 2).…”

“…In contrast, the effect of soil microbial community composition, especially the low-abundant members of the community, are poorly studied. Recent reports on the possible roles of the rare biosphere in ecosystem functioning raise questions about their contribution to plant defence induction relative to introduced PGPR , Delgado-Baquerizo et al 2016. Therefore, the aim of the present study was to test how (loss of) rare soil microbial species influences plant performance and induction of plant defences against aboveground insect herbivores.…”