Microbial biogeography

Source: Wikipedia, the free encyclopedia.

Microbial biogeography is a subset of

microorganisms
. This extension of biogeography to smaller scales—known as "microbial biogeography"—is enabled by ongoing advances in genetic technologies.

The aim of microbial biogeography is to reveal where microorganisms live, at what abundance, and why. Microbial biogeography can therefore provide insight into the underlying mechanisms that generate and hinder biodiversity.[2] Microbial biogeography also enables predictions of where certain organisms can survive and how they respond to changing environments, making it applicable to several other fields such as climate change research.

History

Schewiakoff (1893) theorized about the cosmopolitan habitat of free-living protozoans.[3] In 1934, Lourens Baas Becking, based on his own research in California's salt lakes, as well as work by others on salt lakes worldwide,[4] concluded that "everything is everywhere, but the environment selects".[5] Baas Becking attributed the first half of this hypothesis to his colleague Martinus Beijerinck (1913).[6][7]

Baas Becking hypothesis of cosmopolitan microbial distribution would later be challenged by other works.[8][9][10][11]

Microbial vs macro-organism biogeography

The biogeography of macro-organisms (i.e., plants and animals that can be seen with the naked eye) has been studied since the eighteenth century. For macro-organisms, biogeographical patterns (i.e., which organism assemblages appear in specific places and times) appear to arise from both past and current environments. For example,

selective genetic reasons) restricts the geographical range over which it can be found.[citation needed
]

The biogeography of

geological barriers are irrelevant.[12] However, recent studies show clear evidence for biogeographical patterns in microbial life, which challenge this common interpretation: the existence of microbial biogeographic patterns disputes the idea that "everything is everywhere" while also supporting the idea that environmental selection includes geography as well as historical events that can leave lasting signatures on microbial communities.[2]

Microbial biogeographic patterns are often similar to those of macro-organisms. Microbes generally follow well-known patterns such as the

micrometers vs. meters), time between generations (minutes vs. years), and dispersibility (global vs. local). However, important differences between the biogeographical patterns of microorganism and macro-organism do exist, and likely result from differences in their underlying biogeographic processes (e.g., drift, dispersal, selection, and mutation). For example, dispersal is an important biogeographical process for both microbes and larger organisms, but small microbes can disperse across much greater ranges and at much greater speeds by traveling through the atmosphere (for larger animals dispersal is much more constrained due to their size).[2] As a result, many microbial species can be found in both northern and southern hemispheres, while larger animals are typically found only at one pole rather than both.[15] Furthermore, microorganisms, such as bacteria, are affected by conditions at very small scales that may differ from the scales that are typically considered for macro-organisms. For example, soil bacterial diversity is shaped by the carbon input and connectivity in microscale aqueous habitats.[16]

Distinct patterns

Reversed and non-monotonous latitudinal diversity gradients

Larger organisms tend to exhibit latitudinal gradients in species diversity, with larger biodiversity existing in the tropics and decreasing toward more temperate polar regions. In contrast, studies on indoor fungal communities[14] and global topsoil microbiomes[17] found microbial biodiversity to be significantly higher in temperate zones than in the tropics. Interestingly, different buildings exhibited the same indoor fungal composition in any given location, where similarity increased with proximity.[14] Thus, despite human efforts to control indoor climates, outside environments appear to be the strongest determinant of indoor fungal composition.[14] On the other hand, the strong biogeographical pattern of soil bacteria is typically attributed to changes in environmental factors such as soil pH.[18][19] However, soil pH may be a biogeographical proxy[18] that is affected by a soils climatic water balance,[20] which mediates carbon inputs and the connectivity of bacterial aqueous habitats.[16][21]

Bipolar latitude distributions

Certain microbial populations exist in opposite hemispheres and at complementary latitudes. These 'bipolar' (or 'antitropical') distributions are much rarer in macro-organisms; although macro-organisms exhibit latitude gradients, 'isolation by geographic distance' prevents bipolar distributions (e.g., polar bears are not found at both poles). In contrast, a study on marine surface bacteria[15] showed not only a latitude gradient, but also complementarity distributions with similar populations at both poles, suggesting no "isolation by geographic distance". This is likely due to differences in the underlying biogeographic process, dispersal, as microbes tend to disperse at high rates and far distances by traveling through the atmosphere.[citation needed]

Seasonal variations

Microbial diversity can exhibit striking seasonal patterns at a single geographical location. This is largely due to dormancy, a microbial feature not seen in larger animals that allows microbial community composition to fluctuate in relative abundance of persistent species (rather than actual species present). This is known as the "seed-bank hypothesis"[22] and has implications for our understanding of ecological resilience and thresholds to change.[23]

Applications

Directed panspermia

ecosystems.[25] Thus microbial biogeography can be applied to panspermia as it predicts that microbes are able to protect themselves from the harsh space environment, know to emerge when conditions are safe, and also take advantage of their dormancy capability to enhance biodiversity wherever they may land.[citation needed
]

Extremophiles, although tough enough to withstand the space environment, may not be ideal for directed panspermia as any given extremophile species requires a very specific climate to survive. However, if the target was closer to Earth, such as a planet or moon in our Solar System, it may be possible to select a specific extremophile species for the well-defined target environment.[citation needed
]

See also

References

  1. ISBN 9780878934942.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  2. ^
    S2CID 205496270
    .
  3. ^ Schewiakoff, W.T. 1893. Über die geographische Verbreitung der Süßwasser-protozoen. Mem. Acad. Imp. Sci. St. Petersb. Ser. VII 41, n. 8, 1-201, BHL.
  4. ^ Baas-Becking, L.G.M. (1934). Geobiologie of inleiding tot de milieukunde. The Hague, the Netherlands: W.P. Van Stockum & Zoon, [1]. English translation, 2015, [2].
  5. ^ Translated from the original Dutch: "Alles is overal: maar het milieu selecteert"
  6. PMID 10547690
    .
  7. ^ Beijerinck, M.W. (1913) De infusies en de ontdekking der backteriën. Jaarboek van de Koninklijke Akademie voor Wetenschappen. Amsterdam, the Netherlands: Müller. (Reprinted in Verzamelde geschriften van M.W. Beijerinck, vijfde deel, pp. 119–140. Delft, 1921).
  8. ^ Kristiansen, J. (1996). Biogeography of Freshwater Algae. Dev. Hydrobiol. 118 / Hydrobiol. 336, [3].
  9. ^ Franklin, R. B. & Mills, A. L. (eds.) (2007). The spatial distribution of microbes in the environment. Dordrecht, The Netherlands: Springer, [4].
  10. ^ Foissner, W.; D.L. Hawksworth (2009). Protist Diversity and Geographical Distribution. Dordrecht: Springer, [5].
  11. ^ Fontaneto, D. (2011). Biogeography of Microscopic Organisms. Is Everything Small Everywhere? Cambridge University Press, Cambridge, [6].
  12. S2CID 6724449
    .
  13. S2CID 19575573
    .
  14. ^
    PMID 20616017
    .
  15. ^
    S2CID 44008025
    .
  16. ^
    PMID 31913270
    .
  17. S2CID 51892834
    .
  18. ^
    PMID 16407148
    .
  19. PMID 29348236
    .
  20. S2CID 4466063
    .
  21. PMID 31431661
    .
  22. S2CID 205497982
    .
  23. PMID 22071345
    .
  24. PMID 3312987
    .
  25. PMID 20231463
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Microbial_biogeography&oldid=1213700493"