Functional traits shape gut microbial assembly beyond phylogeny in estuarine fish

Area of Science:

• Microbial Ecology
• Evolutionary Biology
• Fish Biology

Background:

• Host-specific gut microbiomes are common, but the drivers of their assembly, particularly the roles of host phylogeny versus functional traits, are debated.
• Understanding these drivers is crucial for deciphering host-microbiota co-evolution and ecological adaptations.

Purpose of the Study:

• To investigate the relative contributions of host phylogeny and functional traits to gut microbiota composition in 61 fish species from the Pearl River Estuary.
• To identify mechanisms and ecological factors governing gut microbiota assembly and functional adaptations in fish.

Main Methods:

• Integrated host phylogeny and functional trait data with gut microbiota sequencing.
• Employed clustering and machine learning analyses to identify enterotypes.
• Utilized redundancy analysis to link specific functional traits to microbiota patterns.

Main Results:

• Gut microbiota composition varied significantly among fish species, but phylosymbiosis had minimal influence.
• Host functional traits, including feeding strategies, habitat preference, and digestive efficiency, were key drivers of microbiota differentiation.
• Identified three distinct gut enterotypes associated with feeding habits and migratory behaviors, linked to specific metabolic adaptations.
• Functional traits like eye size, oral gape, and gut length significantly influenced enterotype clustering.

Conclusions:

• Host functional traits, rather than host phylogeny, predominantly shape gut microbiota assembly, a phenomenon termed "functsymbiosis".
• This trait-driven congruence highlights the adaptive significance of gut microbiota in fish niche differentiation and fitness.
• Findings provide novel insights into the complex interplay between host traits and symbiotic microbiota in aquatic ecosystems.