A low proportion of rare bacterial taxa responds to abiotic changes compared with dominant taxa.

Viola Kurm,Wilhelmina H Gera Hol,Stefan Geisen

doi:10.1111/1462-2920.14492

Viola Kurm, Wilhelmina H Gera Hol + Show 1 more

Open Access

https://doi.org/10.1111/1462-2920.14492

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Journal: Environmental Microbiology	Publication Date: Dec 19, 2018
Citations: 57	License type: CC BY 4.0

Affiliation: Netherlands Institute of Ecology

Abstract

SummaryIn many studies, rare bacterial taxa have been found to increase in response to environmental changes. These changes have been proposed to contribute to the insurance of ecosystem functions. However, it has not been systematically tested if rare taxa are more likely to increase in abundance than dominant taxa. Here, we study whether rare soil bacterial taxa are more likely to respond to environmental disturbances and if rare taxa are more opportunistic than dominant taxa. To test this, we applied nine different disturbance treatments to a grassland soil and observed changes in bacterial community composition over 7 days. While 12% of the dominant taxa changed in abundance, only 1% of the rare taxa showed any effect. Rare taxa increased in response to a single disturbance treatment only, while dominant taxa responded to up to five treatments. We conclude that rare taxa are not more likely to contribute to community dynamics after disturbances than dominant taxa. Nevertheless, as rare taxa outnumber abundant taxa with here 230 taxa that changed significantly, the chance is high that some of these rare taxa might act as ecologically important keystone taxa. Therefore, rare and abundant taxa might both contribute to ecosystem insurance.

Highlights

Since the discovery that most microbial communities are comprised of a large percentage of rare bacterial taxa, called the ‘rare biosphere’ (Sogin et al, 2006), rare taxa have frequently been shown to contribute to a variety of ecosystem functions
It has been assumed that the high diversity within the rare biosphere increases the probability of including taxa that are adapted to specific abiotic conditions (Flather and Sieg, 2007) and these rare taxa could consequentially support ecosystem functioning after specific environmental changes
We investigate whether rare bacterial taxa behave as opportunists upon disturbances by testing the following hypothesis: (i) Rare bacterial taxa are more likely to exhibit changes in abundance in response to disturbance treatments than dominant taxa; (ii) Rare bacterial taxa increase in abundance in response to more than one disturbance treatment; (iii) Rare taxa will rapidly increase in abundance and decrease again after a disturbance event

Summary

Introduction

Since the discovery that most microbial communities are comprised of a large percentage of rare bacterial taxa, called the ‘rare biosphere’ (Sogin et al, 2006), rare taxa have frequently been shown to contribute to a variety of ecosystem functions. While some rare bacterial taxa have been shown to support specific ecosystem processes more strongly than would be expected from their abundance, it has been demonstrated that many have the ability to become dominant in space and time (Caporaso et al, 2012). At increased abundances, these formerly rare taxa have higher functional importance and take over or supplement functions performed by other dominant taxa (Campbell et al, 2011; Kearns et al, 2017). Previous studies generally tested community changes only in response to a single disturbance treatment or to general seasonal changes (Campbell et al, 2011; Ferrenberg et al, 2013)

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