Recording the biodiversity in rainforests is important for their protection, but also complex because many animals hide from the eyes of scientists in the dense jungle. But there is an easier way, as a new method demonstrates. Accordingly, one can also simply take swabs from leaves with cotton swabs and then analyze them in the laboratory. As the DNA of the forest dwellers is deposited on the leaves, the swabs reveal at a glance who lives in a certain area.
Climate change and human intervention are currently causing biodiversity to decline in many places. In order to find out which animal populations are particularly affected and how they can be helped, precise information is needed about the fauna of the different habitats and ecosystems. But especially in rainforests, where monkeys, birds, etc. can hide in the dense canopy of leaves, this information is often difficult to obtain.
With 24 cotton swabs in the jungle
Christina Lynggaard from the Helmholtz Institute for One Health (HIOH) in Greifswald, together with her colleagues, may have now developed a method that reveals the inhabitants of a forest area more simply and accurately than ever before. The idea came up after the researchers had managed to fish animal DNA out of thin air for the first time in a different context. “If animal DNA is in the air around us, it might settle and stick to sticky surfaces like leaves. The rainforest and its plants are often referred to as ‘the lungs of the planet’. “So could the planet’s lungs be the ideal place to sample DNA that settles in the air?” ponders Lynggaard’s colleague Jan Gogarten.
To test this idea, the team went to the Kibale National Park in Uganda: There, armed with 24 commercially available cotton buds, they dabbed on different leaves for three minutes each. The hopes that they would actually collect the DNA of the forest dwellers were initially low. “To be honest, we didn’t expect great results,” said Lynggaard. “The rain forest is hot and humid, and under these conditions, DNA degrades rapidly.”
Over 50 animal species “caught”
And yet: The DNA sequencing of the leaf swabs was unexpectedly successful. “We found DNA from a stunning variety of animals in these 24 cotton swabs – over 50 species of mammals and birds, plus a frog. And all of that after only 72 minutes of leaf stippling,” reports Gogarten. On average, each cotton swab sample contained the DNA of eight different animal species. Among other things, the researchers found that an African elephant had walked through the area. A hammerhead flying fox, the rare monkey, the endangered Ugandan colobus monkey and the oil palm squirrel also left their DNA in the forest area. There were also numerous birds such as the giant turaco and the endangered gray parrot.
“The large number of animal species detected and the high detection rate per cotton swab show that animal DNA can be dabbed off leaves and then analyzed without any problems,” concludes Gogarten. “On a larger scale, this method could serve as an information basis for recording biodiversity and its loss and deriving strategies for wildlife management from this.” distribute. By collecting data from different forest areas, similar to a Covid-19 swab, the wildlife of the rainforests could be monitored in greater detail than ever before.
This would not only benefit the preservation of ecosystems, but also the health of local people, as the research team explains. Since most emerging infectious diseases originate in wild animal populations, information about the location of different animal species is essential to prevent unwanted pathogen exchange.
Source: Helmholtz Center for Infection Research; Article: Current Biology, doi: 10.1016/j.cub.2023.06.031