PT - JOURNAL ARTICLE AU - Charles K. Fisher AU - Thierry Mora AU - Aleksandra M. Walczak TI - Habitat Fluctuations Drive Species Covariation in the Human Microbiota AID - 10.1101/028209 DP - 2015 Jan 01 TA - bioRxiv PG - 028209 4099 - http://biorxiv.org/content/early/2015/10/02/028209.short 4100 - http://biorxiv.org/content/early/2015/10/02/028209.full AB - Two species with similar resource requirements respond in a characteristic way to variations in their habitat – their abundances rise and fall in concert. We use this idea to learn how bacterial populations in the microbiota respond to habitat conditions that vary from person-to-person across the human population. Our mathematical framework shows that habitat fluctuations are sufficient for explaining intra-bodysite correlations in relative species abundances from the Human Microbiome Project. We explicitly show that the relative abundances of phylogenetically related species are positively correlated and can be predicted from taxonomic relationships. We identify a small set of functional pathways related to metabolism and maintenance of the cell wall that form the basis of a common resource sharing niche space of the human microbiota.