Theory 19/Microbiome strains/Metagenomic sequencing
Strains Replace, Species Persist
The claim
Microbiome stability is set by the ratio of strain replacement rate to species persistence, so a community can look stable at species level while turning over completely beneath it.
01Mechanism
Functions are often strain-specific; replacing a strain changes function without changing the species list.
02Prediction
Functional change should accompany strain turnover at constant species composition.
03Refutation
Function tracking species composition would remove the strain argument.
04What makes it checkable
Deep metagenomics now resolves strains within species, which 16S surveys could not distinguish.
05Why it was not testable before
Genus-level surveys averaged away the unit that actually changes.