MSGID: 1:317/3 642cf968   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    A detailed map of the microverse: Microbial niches    
      
     Date:   
         April 4, 2023   
     Source:   
         Friedrich-Schiller-Universitaet Jena   
     Summary:   
         What defines the habitat -- the ecological niche -- of a   
         microorganism?  It is a combination of environmental factors such   
         as temperature, moisture, and nutrient content. But the exact   
         contribution of each of these factors is difficult to predict. A   
         research team has redefined microbial niches by determining which   
         microorganisms live together.   
      
      
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   FULL STORY   
   ==========================================================================   
   Whether in hot springs, in the human intestine or in the deep sea - -   
   microorganisms colonise almost every place on earth, sometimes under   
   extreme conditions. Depending on how these organisms have adapted to the   
   particular environmental conditions in such ecological niches, ecologists   
   classify them as "generalists" or "specialists." While generalists can   
   cope with a wide range of environmental conditions, specialists grow   
   only under very specific circumstances.   
      
      
   ==========================================================================   
   "A key question for the study of such different microbial strategies   
   is how to define microbial ecological niches in the first place," says   
   Prof. Dr Bas E.   
      
   Dutilh. Until now, this has mainly been done based on subjective   
   environmental parameters, which hardly allow unbiased quantification of   
   the niche. The bioinformatician from the Cluster of Excellence "Balance   
   of the Microverse" at the University of Jena, together with researchers   
   from Utrecht University, has therefore used a novel -- data-driven --   
   method to describe microbial niches, in which the species community   
   itself is considered the decisive environmental factor instead of   
   external habitat conditions. This works because microbial communities   
   adapt rapidly to their environment, so their composition reflects the   
   sum of all environmental factors.   
      
   Most microbial habitats dominated by generalists For their study, the   
   researchers analysed and quantified thousands of metagenomic data sets   
   from different microbial samples from all over the world.   
      
   "We found that in most habitats, generalists are dominant," says   
   Dutilh. The researchers were initially surprised by this finding,   
   as they had assumed that in local niches, specialists might prevail   
   because they are better adapted to the particular conditions. But they   
   found that competing generalists could grow much faster and thus gain   
   dominance in the niche. "For the generalists it's hit-or-miss, though;   
   either they make it or they don't. This makes them quite variable in   
   their presence. Specialists are more stable in their niche, albeit   
   at low abundance."  And there was another result that the researchers   
   had not expected: The genomes of the generalists are not particularly   
   large. "This was previously assumed because metabolic flexibility was   
   thought to generally require a larger genome," reports Dutilh. But as   
   it turns out, the correlation between niche range and genome size is   
   more complex. "We discovered two contrasting evolutionary strategies: In   
   habitats with relatively low local biodiversity, such as animal-associated   
   microbiomes, the specialists have a relatively small genome. In highly   
   biodiverse habitats such as soils, the genome of the specialists is   
   significantly larger."  The genomes of generalists are more variable than   
   those of specialists, with genes coming and going during evolution. This   
   allows them to integrate genetic information from other organisms through   
   horizontal gene transfer and thus to adapt rapidly to the local niche. "We   
   also see specific functions that are associated with horizontal gene   
   transfer in generalists' genomes," according to Dutilh. The functions   
   associated with specialists are much more diverse, often related to   
   very specific metabolic processes. The genomes of specialists are   
   evolutionarily stable, unlike those of generalists.   
      
   "In conclusion, our analysis sheds new and unexpected light on microbial   
   niche range strategies throughout the microbial tree of life," Bas   
   E. Dutilh is convinced.   
      
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Nature # Microbes_and_More # Evolutionary_Biology #   
                   Microbiology   
             o Earth_&_Climate   
                   # Ecology # Environmental_Awareness # Environmental_Issues   
                   # Earth_Science   
       * RELATED_TERMS   
             o Ecological_niche o Competitive_exclusion_in_ecology o   
             Ecological_succession o Environmental_impact_assessment o   
             Honey o Hip_dysplasia o Heritability o Microorganism   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Friedrich-Schiller-Universitaet_Jena. Original written by Ute   
   Scho"nfelder. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. F. A. Bastiaan von Meijenfeldt, Paulien Hogeweg, Bas E. Dutilh. A   
      social   
         niche breadth score reveals niche range strategies of generalists   
         and specialists. Nature Ecology & Evolution, 2023; DOI:   
         10.1038/s41559-023- 02027-7   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/04/230404114309.htm   
      
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