It is interesting to note that the Clostridia clade harbors cosmopolitan families, such as Peptococcaceae, and environment-specific ones such as Lachnospiraceae or Oscillospiraceae. This indicates that phylogenetically close families can show strikingly different environmental preferences and distribution

patterns, which at least for some cases, questions the validity of the proposed relationship VRT752271 mw between phylogenetic distance and environmental preferences [26, 27]. Taxonomic distributions can be used to explore the characteristics of the environments themselves. Grouping environments according to similarity in their taxonomic profiles can help us to understand the main environmental features at play in selecting prokaryotic diversity. To assess the relationship between environments https://www.selleckchem.com/products/Cyt387.html and taxa, WZB117 price we clustered the different environmental types according to the affinities of their different taxa (Figure 3). Figure 3 Relations between environments, and between environments and taxonomic families. Heat-map of the posterior medians of the affinities and the resulting dendrogram

from the cluster analysis of the environment types, using log-affinities and euclidean distance. Purple and orange cells represent low and high affinity values, respectively. The environments are separated into five different groups. The first one is associated with animal tissues (oral, gut, vagina, other human tissues, samples from animal tissues and aerial specimens, the last mostly coming from air expired from human subjects). These habitats clearly differ from the rest, and some of the prokaryotes click here living there do not thrive in other locations [28]. Thus, host association with animals emerges as the first discriminating factor in the composition of the prokaryotic assemblages. The second group to segregate is composed of thermal environments (geo- and hydrothermal), and also shows a clearly distinct taxonomic

profile. Both environments are separated by long distances in the dendrogram, which indicates significant differences between them. The absence of oxygen and light in hydrothermal locations accounts for the presence of some anaerobic methanogenic archaea in hydrothermal, but not geothermal sources, or for some photosynthetic cyanobacterial families that are located only in geothermal spots where light is present. The third group comprises saline environments, and is represented mainly by heterogeneous marine samples which show quite similar profiles. Athalassohaline waters of saline inland lakes (including soda lakes, with a mineral composition different from marine waters) also cluster within this group, showing that salinity as a whole, and not salt composition, is the determinant ecological factor. This is related to osmotic adaptations of the organisms. The fourth group contains terrestrial samples from soil and plants.