Bacteria of the Humboldt sulfuretum comply with unifying macroecological principles

The next generation sequencing (NGS) tools available today, i.e., 454 Roche pyrosequencing (Shendure and Ji 2008) allow metagenomic studies on the composition and structure of microbial communities in a way that it was not possible before (Handelsman 2004). In the field of macroecology, early studies showed that fresh water and marine benthic invertebrate communities varied in their structure, i. e., number of species (species richness) and relative abundance among species (dominance or lack of it) (Thienemann 1939; Sanders 1968). From their work, we here construct the “Thienemann-Sanders time-stability (TS2) hypothesis” which predicts that the older and more stable the habitat the higher the species richness and diversity with a lack of dominance by any member in the community. The contrary would be the case in younger and/or drastically varying habitats. The former conditions would render a “biologically accommodated” community while the latter a “physically controlled” community. Ward et al. (1998) suggested that: “By adopting the view of macroecologists and macroevolutionary biologists as they interpret their findings, microbial ecologists can see if unifying principles control the diversity, ecology, and evolution of all organisms, large and small”. The question thus is: Does the “TS2 hypothesis” fit prokaryotic communities? As a test, here we show the results of the analysis of relative operational taxonomic unit (OTU=species proxies) abundance data of benthic bacteria from the Humboldt Sulfuretum (HS). The analysis disclosed high values of species richness, a lack of dominants, high information diversity indices, and steep rarefaction curves, all features pointing to an evolutionarily mature, “biologically accommodated” community consistent with the TS2 hypothesis. Thus, this study suggests that bacterial communities of old environments such as a sulfuretum comply with macroecologically-derived principles.