The community structure of the human microbiome is the result of a multifactorial process that involves succession over time [24], is influenced by host genetics [25], and is affected by lifestyle choices [26, 27]. Communities are made up of thousands of microbial species, with the predominant microbial biomass residing in the human large intestine. Fascinatingly, within the human gastrointestinal tract, it appears that multiple organisms are capable of fulfilling common ecological niches, leading to remarkably different microbial communities that possess similar functional potential [3]. Furthermore, while variations in the human genome are minute across the population, variations in the human microbiome on geographical and temporal scales are immense [28, 29]. Despite investments of hundreds of millions of dollars, we still do not understand the distribution of community structures in healthy individuals [30], but we do know that when studies of the microbiome are performed without a concern for integration with existing studies, effects of significant biological importance can be easily missed [31].
