Worried about biological invasion? Clues can be found in the air

  Researchers at Texas Tech University have demonstrated that simply capturing and analyzing the DNA that plants release into the air can help track how climate change is changing the composition of plant communities and provide early warnings of invasive species. The findings were published in BMC Ecology and Evolution.
  Plants release a tracer in the air that will be familiar to anyone with allergies: wind-pollinated pollen. The unique shape of these particles allows one to identify unseen species by capturing pollen. But pollen surveys have their limitations, too. They only detect wind-borne pollen (other types rely on insects and other animals for pollination), require trained experts, and don’t always identify specific species.
  Environmental DNA (eDNA) refers to genetic material released into the environment by shedding, defecation, coughing, or otherwise. Mark Johnson, a graduate student at Texas Tech University, wondered if it would be more effective to study eDNA released into the air in the form of pollen or tiny fragments of leaves and flowers.
  So Johnson et al. developed a new method for collecting plant eDNA in dust collectors, which allows them to find species that don’t bloom, pollinate, or find them when they’re not active in winter.
  Johnson shows how eDNA can “count” entire plant communities. The research team installed dust collectors at nine locations on a well-studied short meadow. Every few weeks over the course of the year, they collected dust, extracted DNA, and sequenced the genes of different plants as “DNA barcodes” to identify them.
  Meanwhile, in spring and fall, the researchers surveyed the vegetation of the grassland along 27 100-meter transects and compared the results of the two surveys.
  The results showed that traditional survey methods identified 80 species, while airborne eDNA studies identified 91. Both surveys found the same 13 grass species, but the eDNA approach found another 13. In addition, the two methods found a total of 60 species of non-woody flowering plants, but both methods were able to detect about 20 species that the other missed.
  The researchers report that eDNA is better at spotting species of small flowers that are easily overlooked, such as ragweed. But traditional methods are better at spotting plants that are too rare to release much eDNA, especially when they have showy flowers like chocolate daisies.
  The airborne DNA also revealed an invasive plant, the “Sky Tree”, that the survey had not found. Loren Rieseberg, a plant evolutionary biologist at the University of British Columbia in Canada, said: “eDNA will be particularly helpful for early detection of invasive species before they become widespread and difficult to remove.”
  It is worth mentioning that this technology also records How the abundance of different species has changed over time. For example, in early spring, rapid flowering and growth of tansy mustard. In addition to plant DNA, the filter can also extract DNA from fungi, and other researchers have extracted DNA from insects, earthworms and slugs from the air.

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