Is Everything Everywhere? Dispersal Limitation Impacts Methanotroph Community Functioning

Area of Science:

• Microbial Ecology
• Biogeography
• Environmental Microbiology

Background:

• The 'everything is everywhere' hypothesis suggests microbial dispersal is unlimited, but its functional implications are debated.
• Understanding dispersal limitation is crucial for predicting microbial community adaptation to environmental changes, such as increasing salinity.

Purpose of the Study:

• To investigate the role of dispersal limitation in the adaptation of methanotroph communities to salt stress.
• To test the 'everything is everywhere' hypothesis in functional terms within microbial ecology.

Main Methods:

• Collected riparian and inland sediment samples along the Yangtze River.
• Incubated microcosms with methane under high salinity conditions, with and without methanotroph inoculation.
• Utilized DNA-stable isotope probing (DNA-SIP) to identify active microbial taxa.

Main Results:

• High salinity significantly delayed methane oxidation, but salt-tolerant activity persisted in riparian sediments.
• Halotolerant Methylobacter taxa were identified, likely originating from saline estuaries.
• Methane oxidation failed to occur in inland samples without inoculation, but was restored upon addition of riparian inoculum.

Conclusions:

• Dispersal limitation of halotolerant microbes, specifically Methylobacter, constrains ecosystem functional adaptation to salinity.
• This study demonstrates that microbial dispersal limitation can impact ecosystem functions on a broad scale, challenging the 'everything is everywhere' paradigm.