BLOOMINGTON, Ind., May 3 (UPI) -- A new study suggests our knowledge of Earth's biodiversity is extremely limited. According to the numbers recently crunched by scientists at Indiana University, 99.999 percent of the planet's species remain undiscovered.
Using a series of large data sets, ecological models and global scaling laws, researchers estimated that Earth likely hosts upwards of 1 trillion species. Their models incorporated data sets on microbial, plant and animal communities compiled by governments, academic institutions and citizen scientists.
The data sets encompassed sampling results for both microscopic organisms and non-microscopic organisms, including data from 20,376 samples of bacteria, archaea and microscopic fungi communities. Another 14,862 samples informed the model's understanding of Earth's communities of trees, birds and mammals.
In all, the models accounted for 5.6 million species from 35,000 locations across all of Earth's continents except Antarctica.
"Estimating the number of species on Earth is among the great challenges in biology," biologist Jay T. Lennon, an associate professor at Indiana, said in a news release. "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."
An improved understanding of microbial diversity was essential to their efforts, Lennon said.
"Until recently, we've lacked the tools to truly estimate the number of microbial species in the natural environment," Lennon added. "The advent of new genetic sequencing technology provides an unprecedentedly large pool of new information."
Lennon and his colleagues combined their newly amassed wealth of ecological data and their improved microbial sampling analysis with an evolved understanding of how biodiversity relates to abundance.
"After analyzing a massive amount of data, we observed simple but powerful trends in how biodiversity changes across scales of abundance," explained Kenneth J. Locey, a postdoctoral fellow in Indiana's biology department. "One of these trends is among the most expansive patterns in biology, holding across all magnitudes of abundance in nature."
This understanding, combined with global scaling laws, allowed researchers to arrive an estimate for Earth's potential biodiversity.
"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 the estimate of upwards of 1 trillion species."
The researchers shared their findings in a new paper published this week in the journal PNAS.