Morphological complexity affects the diversity of marine microbiomes

Area of Science:

• Marine biology
• Microbial ecology
• Phycology

Background:

• Large eukaryotes host diverse surface microbes (epibiota) influencing host biology.
• Factors like host evolution, environment, and chance shape microbial diversity, but their interplay is complex.
• Disentangling these factors is crucial for understanding host-microbe interactions.

Purpose of the Study:

• To investigate the drivers of epibiotic community structure in seaweeds.
• To determine the relative importance of host phylogeny, morphology, and environment on epibiotic diversity.
• To explore the role of habitat complexity in structuring host-associated microbial communities.

Main Methods:

• Surveyed epibiota from 38 sympatric seaweed species with diverse clades and convergent morphology.
• Analyzed epibiotic community variation in relation to host identity, phylogeny, and morphology.
• Experimentally tested the effect of seaweed morphology on bacterial community assembly using artificial substrates.

Main Results:

• Host identity was the primary driver of epibiont community variation.
• Host morphology significantly influenced epibiota composition and richness, with complexity increasing diversity.
• Experimental validation confirmed morphology's role in bacterial community assembly, mirroring field observations.

Conclusions:

• Seaweed morphology, particularly structural complexity, is a key, underexplored factor structuring epibiotic communities.
• Biodiversity increases with habitat complexity in host-associated microbial systems, analogous to patterns in animal communities.
• Host morphology offers a significant mechanism for regulating the diversity and composition of associated microbial life.