Associations Between Gut Microbiota Diversity and a Host Fitness Proxy in a Naturalistic Experiment Using Threespine...

Area of Science:

• Ecology
• Microbiology
• Evolutionary Biology

Background:

• The vertebrate gut microbiota significantly influences host functions.
• The impact of gut microbial communities on host fitness in natural settings is not well understood.

Purpose of the Study:

• To investigate the relationship between gut microbiota diversity and composition and host fitness in threespine stickleback fish under naturalistic conditions.
• To determine if microbial community structure correlates with individual growth rate, a proxy for fitness.

Main Methods:

• Characterized associations between growth rate and bacterial gut microbiota diversity (α-diversity) and composition (β-diversity).
• Utilized threespine stickleback fish introduced to large semi-natural ponds.
• Applied a neutral community model to assess bacterial dispersal patterns.

Main Results:

• High-fitness fish exhibited 63% higher bacterial taxon richness (α-diversity) compared to low-fitness fish.
• Microbial communities of high-fitness fish were more similar to each other (lower β-diversity) than those of low-fitness fish.
• Findings align with the Anna Karenina principle, suggesting fewer ways to achieve a functional microbiota.

Conclusions:

• Gut microbiota α-diversity and β-diversity are linked to host fitness traits in vertebrates under naturalistic conditions.
• A more structured and diverse gut microbiota may be essential for optimal host fitness.
• Results provide a foundation for future studies on the functional consequences of host-microbiota interactions on fitness.