Assessing the biodiversity of an area is one of those dirty jobs that somebody's gotta do. But researchers in Denmark and Australia have devised a way to shortcut the classical technique of calculating biodiversity, which involves time and labor intensive methods of trapping and tagging various animals in a given ecosystem. A faithful representation of which species and how many individuals of each inhabit a particular area can instead by gleaned from DNA samples lurking in the soil, they report in a paper published this month in Molecular Ecology.
"This is the first time anyone has shown that 'dirt' DNA not only reflects what species live in an area, but how many [individuals] there are," evolutionary biologist and study coauthor Eske Willerslev told Nature. Willerslev and his colleagues ran mitochondrial DNA samples from soil collected in Danish safari parks and zoos through high-throughput sequencers, scanning for fragments of genetic material that could identify organisms at the species level. Not only were the researchers successful in identifying species present in the parks, they were also able to accurately estimate the biomass of the species present based on the relative abundance of their DNA in the soil.
There are several caveats to using the method, however. For example, soil leeching can be a problem, and animal behavior could influence how much of a particular species' DNA ends up in the soil. Still, the quick and dirty estimator of the biodiversity can potentially save ecologists time and money by freeing them from traditional capture and tag methods.