Functional and Compositional Stability of Bacterial Metacommunities in Response to Salinity Changes

Abstract

Disturbances and environmental change are important factors determining the diversity, composition, and functioning of communities. However, knowledge about how natural bacterial communities are affected by such perturbations is still sparse. We performed a whole ecosystem manipulation experiment with freshwater rock pools where we applied salinity disturbances of different intensities. The aim was to test how the compositional and functional resistance and resilience of bacterial communities, alpha- and beta-diversity and the relative importance of stochastic and deterministic community assembly processes changed along a disturbance intensity gradient. We found that bacterial communities were functionally resistant to all salinity levels (3, 6, and 12 psu) and compositionally resistant to a salinity increase to 3 psu and resilient to increases of 6 and 12 psu. Increasing salinities had no effect on local richness and evenness, beta-diversity and the proportion of deterministically vs. stochastically assembled communities. Our results show a high functional and compositional stability of bacterial communities to salinity changes of different intensities both at local and regional scales, which possibly reflects long-term adaptation to environmental conditions in the study system.

Disturbance history can increase functional stability in the face of both repeated disturbances of the same type and novel disturbances

“…In addition, our results indicate a larger change in community composition for the 35 °C than for the 25 °C treatment. This is in agreement with results from previous studies using other types of disturbances, which showed, for example, that bacterial community composition changed gradually with increasing intensities and frequencies of a salinity disturbance 13,32 or increasing concentration of a pollutant 14 . Moreover, the results clearly show a lack of compositional recovery in response to the applied temperature disturbances.…”

Inorganic Nitrogen Application Affects Both Taxonomical and Predicted Functional Structure of Wheat Rhizosphere Bacterial Communities

“…We had assumed that FYM application would have resulted in a higher functional diversity due to the more varied range of substrates and an increased species richness in this treatment. This implies that there is a greater amount of microbial functional redundancy ( Taketani et al, 2015 ; Berga et al, 2017 ) in the FYM treated strip. Future work should determine whether or not this is the case through metagenomics as well as microbial isolate sequencing efforts.…”

Community-level signatures of ecological succession in natural bacterial communities

“…The development of a more mechanistic picture is hindered for several reasons, such as difficulties in identifying the relative role of stochastic and deterministic processes in shaping microbial communities [5][6][7] , and the pervasiveness of functional redundancy 8,9 and of priority effects 10 . In addition, it is often difficult to identify which functions to assess.…”

“…An important step forward comes from manipulative experiments in natural environments, which have identified variables such as pH 12 , salinity 8 , sources of energy 13 , the number of species 14 and environmental complexity 4 as key players in the relationship between bacterial community structure and functioning. Improved control can be obtained by domesticating communities surveyed from natural environments by growing them in a synthetic (albeit complex) environment, and quantifying their functioning under such controlled conditions 15,16 .…”