The new estimate of microbial biodiversity puts the number of different species of microorganisms at somewhere between 100 billion and 1 trillion (which seems like a big difference, although when expressed as logarithms is actually just on log difference.)
The new estimate, which comes from microbiologists working at the Indiana University, is considerably above the current estimate of 10 million. Of course the researchers haven’t found these organisms, these mathematical estimates. Should the figures be true, then there are a very high number of species left to discover.
The estimate is drawn from available surveys and datasets relating to microbes, plants and animals drawn from information provided from government, academic and citizen science projects. The researchers are hailing this as the largest compilation yet undertaken. Here some 20,376 surveys were reviewed.
In a research brief, the head of the project, Jay Lennon, noted: “Our study combines the largest available datasets with ecological models and new ecological rules for how biodiversity relates to abundance. This gave us a new and rigorous estimate for the number of microbial species on Earth.”
The figure relating to the probable numbers of microorganisms came from scaling theory. Scaling laws are used to predict species numbers for plant and animal communities.
In recent years studies have suggested the extent of microbial life is far greater than previously realized. This realization has been aided by high-throughput sequencing and bioinformatics. These techniques have considerably expanded the catalog of microbial taxa by several orders of magnitude. In addition, newly discovered phyla are reshaping the tree of life.
Even with these methods, scientists may only have just scratched the surface of microbial abundance. Here the prediction for Earth’s microbial diversity stresses the need for continued investigation
The research and model are published in the journal Proceedings of the National Academy of Sciences. The paper is titled “Scaling laws predict global microbial diversity.”
