How Many Species Can You Find in That Soup?

DNA metabarcoding can pick out thousands

Swedish biologist Carl Linnaeus revolutionized biology in the 1700s with his system for classifying every creature on Earth. But collecting and cataloguing the planet’s myriad life forms has been a laborious, slow process. Now, a blender and some emerging genetic techniques could change all that, allowing researchers to track changes in biodiversity at speeds and scales never before imagined.

The DNA technology is known as “metabarcoding.” It allows researchers to rapidly screen environmental samples, such as a scoop of soil or a cup of water, for genetic signatures that reveal how many species are present. Whether metabarcoding could be as accurate as traditional biodiversity surveying methods, however, has been something of a question.

To find out, a group working in China recently used metabarcoding to survey moth populations. Working along transects at different elevations in the subtropical forests of Yunnan province, researchers collected thousands of moths, using light traps. Then they blended them into an “insect soup” that was run through a genetic sequencer. The scientists identified more than 1,000 species in the sample. That was about the same number identified by experts using more conventional techniques—but metabarcoding took less than one-fourth the time. (1)

And it works on more than just insect smoothies.  A group from Stanford University and the University of Washington used a similar approach to analyze the DNA in two glasses of water scooped from a 1.2 million-gallon sealife tank at the Monterey Bay Aquarium in California. The drifting DNA came from tiny bits of tissue and waste released by fish and other creatures. The researchers were able not only to identify seven of eight types of fish living in the tank but also to determine which species were most plentiful. (2) That could open the door, said study leader Ryan Kelly, to using the technology to more easily survey fish populations in the open ocean. DNA soup, anyone?

—Megan Molteni

1. Ji, Y et al. 2013. Ecology Letters doi: 10.1111/ele.12162.

2. Kelly, R.P. et al. 2014. PLoS ONE doi: 10.1371/journal.pone.0086175.

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