Interactions in self-assembled microbial communities saturate with diversity

Area of Science:

• Ecology
• Microbial Ecology
• Community Ecology

Background:

• Understanding how species diversity impacts ecological functions in natural microbial communities is challenging due to high species richness.
• Previous studies have not fully explored the scaling effects of interactions with diversity in these complex systems.

Purpose of the Study:

• To investigate the relationship between microbial diversity and community function in self-assembled communities.
• To determine the point at which increasing species richness no longer significantly affects community function.

Main Methods:

• Generated microbial communities with varying diversity by diluting seawater and growing on algal leachate.
• Isolated dominant taxa to compare individual and community productivity.
• Defined relative total function (RTF) to quantify the impact of diversity on function.

Main Results:

• Three distinct diversity regimes were identified: low (<12 taxa), moderate (12-26 taxa), and high (>26 taxa).
• In moderate richness, resource uptake increased, but carbon use efficiency decreased.
• Community function saturated beyond 26 taxa, with no significant changes observed with further diversity increases.

Conclusions:

• Ecological interactions like competition and complementation increase with diversity but reach a saturation point.
• While diverse communities access more resources, individual taxa may experience reduced resource availability and efficiency.
• A diversity threshold exists beyond which additional species do not enhance or alter community function.