Diatom Cooccurrence Shows Less Segregation than Predicted from Niche Modeling

Area of Science:

• Ecology
• Microbial Ecology
• Community Ecology

Background:

• Species cooccurrence patterns reveal community assembly processes.
• Cooccurrence analyses are common in animals and plants, but less so for microorganisms.
• Understanding microbial cooccurrence is crucial for ecological insights.

Purpose of the Study:

• To investigate stream diatom cooccurrence patterns in France.
• To assess the influence of environmental, biotic, and spatial factors on diatom distribution.
• To compare real community patterns with null model simulations.

Main Methods:

• Utilized a national database of stream diatom samples from France.
• Compared observed cooccurrence and nestedness patterns with standard and environmentally constrained null models.
• Analyzed species incidence distribution to infer community assembly rules.

Main Results:

• Real diatom communities exhibited more segregation than standard null models.
• Observed communities showed aggregation compared to environmentally constrained null models.
• No evidence of limiting similarity was found; aggregation correlated with high nestedness.

Conclusions:

• Biotic interactions likely do not structure diatom cooccurrences at the scale studied.
• Colonization patterns, mass effects, and local biofilm dynamics are probable structuring factors.
• Combining standard and environmentally constrained null models offers realistic insights into microbial cooccurrence.