The Importance Of Global Microbial Diversity

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For a long term, the prevailing logic in global microbial diversity has been “everything is everywhere, but nature selects”, coming from Baas Becking’s 1934 publication, “Geobiologie of inleiding tot de milieukunde” (Baas Becking, 1934). This conclusion was based on the presumption that physical, chemical, and geographical barriers play no role in the global dispersal of microbes, which aerosolise for easy distribution. In this scenario, it would be expected that any given species of microbe could be found at any given location, however a microbe’s abundance at a location would vary based on environmental conditions select for or against them. This scenario would also predict global gene flow, and no evolutionary patterns that correlate with …show more content…
Further challenging “everything is everywhere”, Fierer and Jackson proposed that soil microbial communities should exhibit predictable biogeographical patterns on a continental scale, in a manner similar to that of plants and animals. Collecting 98 soil samples across North and South America, they utilised a 16S rRNA fingerprinting approach to investigate diversity and community structure across these sites. This lead to the discovery that, of all soil parameters measured, pH most reliably predicted both bacterial community diversity and richness. Distinct bacterial communities were found to be associated with pHs across the range discovered; clusters of similar communities were found at separate sites with arid soils, acidic soils, temperate rainforests, and so on. These results were surprising, as they reinforced Becking’s notion of a global bacterial population selected for by environment, demonstrated by the environmental factor of pH acting as a clear control on soil bacterial community composition, unlike geothermal pools in which geographical distance was instead a controlling factor. It could also be concluded therefore that, at least in America, soil microbial biogeography does not follow geographical trends of larger organisms (Fierer & Jackson,

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