Host and microbiome jointly contribute to environmental adaptation

Area of Science:

• Microbiology
• Evolutionary Biology
• Genomics

Background:

• Microbiomes, the microorganisms associated with hosts, are vital for essential functions.
• Host-microbiome assemblages (metaorganisms) have potential for adaptation, possibly faster than host genomes alone.
• The joint contribution of hosts and microbiomes to adaptation is not fully understood.

Purpose of the Study:

• To disentangle the contributions of hosts and microbiomes to metaorganism adaptation in a novel environment.
• To investigate how microbiome composition and host genetics interact during adaptation.
• To provide experimental evidence for joint host-microbiome adaptation.

Main Methods:

• Established replicate mesocosms with Caenorhabditis elegans and microorganisms in laboratory compost.
• Cultured populations for approximately 30 nematode generations (100 days).
• Utilized a common garden experiment to analyze microbiome composition, host genetics, and gene expression.

Main Results:

• Adaptation trajectories varied across mesocosm lines, with some increasing and others decreasing in fitness.
• Interactions between host and microbiome significantly influenced contrasting evolutionary paths.
• Specific changes in bacterial/fungal composition and nematode gene expression were linked to fitness changes.

Conclusions:

• Host and microbiome jointly influence adaptation to novel environments.
• Microbiome dynamics and host genetics interact to shape metaorganism evolution.
• This study provides a model system for dissecting host-microbiome co-adaptation.