Largest analysis of microbial data reveals that 99.999 percent of all species remain undiscovered
Earth could contain nearly 1 trillion species, with only one-thousandth of 1 percent now identified, according to the results of a new study.
The estimate, based on universal scaling laws applied to large datasets, appears today in the journal Proceedings of the National Academy of Sciences. The report's authors are Jay Lennon and Kenneth Locey of Indiana University in Bloomington, Indiana.
The scientists combined microbial, plant and animal datasets from government, academic and citizen science sources, resulting in the largest compilation of its kind.
Altogether, these data represent more than 5.6 million microscopic and non-microscopic species from 35,000 locations across all the world's oceans and continents, except Antarctica.
Great challenge in biology
"Estimating the number of species on Earth is among the great challenges in biology," Lennon said. "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."
He added that "until recently, we've lacked the tools to truly estimate the number of microbial species in the natural environment. The advent of new genetic sequencing technology provides a large pool of new information."
The work is funded by the National Science Foundation (NSF) Dimensions of Biodiversity program, an effort to transform our understanding of the scope of life on Earth by filling major gaps in knowledge of the planet's biodiversity.
"This research offers a view of the extensive diversity of microbes on Earth," said Simon Malcomber, director of the Dimensions of Biodiversity program. "It also highlights how much of that diversity still remains to be discovered and described."
Estimating numbers of microbial species
Microbial species are forms of life too small to be seen with the naked eye, including single-celled organisms such as bacteria and archaea, as well as certain fungi.
Many earlier attempts to estimate the number of species on Earth ignored microorganisms or were informed by older datasets based on biased techniques or questionable extrapolations, Lennon said.
"Older estimates were based on efforts that dramatically under-sampled the diversity of microorganisms," he added. "Before high-throughput genetic sequencing, scientists characterized diversity based on 100 individuals, when we know that a gram of soil contains up to a billion organisms, and the total number on Earth is more than 20 orders of magnitude greater."
The realization that microorganisms were significantly under-sampled caused an explosion in new microbial sampling efforts over the past several years.
Extensive sampling efforts
The study's inventory of data sources includes 20,376 sampling efforts on bacteria, archaea and microscopic fungi, as well as 14,862 sampling efforts on communities of trees, birds and mammals.
"A massive amount of data has been collected from these surveys," said Locey. "Yet few have tried to pull together all the data to test big questions."
He added that the scientists "suspected that aspects of biodiversity, like the number of species on Earth, would scale with the abundance of individual organisms. After analyzing a massive amount of data, we observed simple but powerful trends in how biodiversity changes across scales of abundance."
Scaling laws for all species
The researchers found that the abundance of the most dominant species scales with the total number of individuals across 30 orders of magnitude, "making it the most expansive scaling law in biology," says Lennon.
Scaling laws, like that discovered by the scientists, are known to accurately predict species numbers for plant and animal communities. For example, the number of species scales with the area of a landscape.
"Until now, we haven't known whether aspects of biodiversity scale with something as simple as the abundance of organisms," Locey said. "As it turns out, the relationships are not only simple but powerful, resulting in our estimate of upward of one trillion species."
The study's results also suggest that identifying every microbial species on Earth presents a huge challenge.
"Of those species cataloged, only about 10,000 have ever been grown in a lab, and fewer than 100,000 have classified genetic sequences," Lennon said. "Our results show that this leaves 100,000 times more microorganisms awaiting discovery -- and 100 million to be fully explored.
"Microbial biodiversity, it appears, is greater than we ever imagined."
Cheryl Dybas | EurekAlert!
Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter
17.08.2017 | Swansea University
Climate change: In their old age, trees still accumulate large quantities of carbon
17.08.2017 | Universität Hamburg
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
21.08.2017 | Materials Sciences
21.08.2017 | Health and Medicine
21.08.2017 | Materials Sciences