[FeFe]-hydrogenase in Yellowstone National Park:evidence for dispersal limitation and phylogeneticniche conservatism

Boyd, Eric; Hamilton, Trinity; Spear, John; Lavin, Matthew; Peters, John

Hydrogen (H2) has an important role in the anaerobic degradation of organic carbon and is the basisfor many syntrophic interactions that commonly occur in microbial communities. Little is known,however, with regard to the biotic and/or abiotic factors that control the distribution andphylogenetic diversity of organisms which produce H2 in microbial communities. In this study,we examined the [FeFe]-hydrogenase gene (hydA) as a proxy for fermentative bacterial H2production along physical and chemical gradients in various geothermal springs in YellowstoneNational Park (YNP), WY, USA. The distribution of hydA in YNP geothermal springs wasconstrained by pH to environments co-inhabited by oxygenic phototrophs and to environmentspredicted to have low inputs of abiotic H2. The individual HydA asssemblages from YNP springswere more closely related when compared with randomly assembled communities, which suggestsecological filtering. Model selection approaches revealed that geographic distance was the bestexplanatory variable to predict the phylogenetic relatedness of HydA communities. This evinces thedispersal limitation imposed by the geothermal spring environment on HydA phylogenetic diversityeven at small spatial scales. pH differences between sites is the second highest ranked explanatoryvariable of HydA phylogenetic relatedness, which suggests that the ecology related to pH imposesstrong phylogenetic niche conservatism. Collectively, these results indicate that pH has imposedstrong niche conservatism on fermentative bacteria and that, within a narrow pH realm, YNP springsare dispersal limited with respect to fermentative bacterial communities.

[FeFe]-hydrogenase in Yellowstone National Park:evidence for dispersal limitation and phylogeneticniche conservatism

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