The balance between deterministic and stochastic processes in structuring lake bacterioplankton community over time

Area of Science:

• Microbial Ecology
• Freshwater Ecology
• Community Ecology

Background:

• Understanding ecological processes driving microbial community assembly is crucial for predicting biodiversity changes.
• The relative quantitative contributions of deterministic and stochastic processes, especially over time, remain poorly understood.

Purpose of the Study:

• To quantitatively assess the importance of deterministic and stochastic processes in bacterial microbiome assembly.
• To investigate how these processes vary across different temporal scales (daily, weekly, annual).

Main Methods:

• Analysis of bacterial microbiome data from alpine and subalpine lakes sampled over two years.
• Quantification of community turnover attributed to homogeneous selection (deterministic) and homogenizing dispersal (stochastic).

Main Results:

• Homogeneous selection was the primary driver of annual bacterial community turnover (66.7%) in both lakes.
• Homogenizing dispersal dominated short-term (daily/weekly) turnover (55%) in the alpine lake.
• Alpha diversity varied between lakes, with greater seasonal stability in the oligotrophic lake.

Conclusions:

• Deterministic processes are dominant in structuring freshwater bacterial communities over annual time scales.
• Stochastic processes play a significant role in short-term community dynamics, particularly in certain environments.
• Ecological forces governing temporal changes in bacterial communities operate distinctly at different time scales.