Spiders spin webs to catch prey. They’re also trapping a wealth of genetic information
Silken webs are used by spiders to entangle flies and other small prey. A wealth of DNA from the surrounding environment is also being captured by them; according to Australian scientists, this untapped resource might be utilized to track endangered species and keep an eye on ecosystems.
According to a study published last week in the journal iScience, spiderwebs collected from two locations in Perth, Western Australia, namely Perth Zoo and the Karakamia woodland sanctuary, revealed the genetic signature of ninety-three animals, including native kangaroos and koalas as well as captive elephants and zebras.
Dr. Joshua Newton, a PhD student at Curtin University’s School of Molecular and Life Sciences near Perth, who coauthored the paper, believes that spiderwebs might be a helpful tool for keeping an eye on the creatures that are nearby.
According to a news statement from Newton, “These webs, often overlooked in biodiversity studies, proved to be reservoirs of genetic information.”
“This inexpensive and non-invasive method could revolutionize our understanding of and efforts to preserve our terrestrial biodiversity, as it requires only trace amounts of DNA to identify animals.”
Environmental DNA, or eDNA, is the genetic material that all living things leave behind in the form of skin cells, hair, or body fluids.
Researchers have found evidence of animal DNA in the atmosphere. In two proof-of-concept investigations that were published in 2022, air samples from Hamerton Zoo Park in the United Kingdom and Copenhagen Zoo in Denmark were used to retrieve the DNA of many animals.
The Australian study expands on this concept by removing the requirement for any special tools, like an air filter or fan, in order to gather the sample.
According to the authors, webs are “found in an array of microhabitats worldwide, ubiquitous in many natural and anthropogenic environments, and naturally selected to act as sticky traps.”
Furthermore, spiderwebs are quite simple to gather, according to Newton. I compare it to the scene in Shrek where Princess Fiona crafts a spiderweb out of fairy floss for Shrek. She simply ties everything up with a stick. I essentially do it,” he clarified. “We use fairly standard extraction methods to extract the DNA from it once I bring it back into the lab.”
eDNA techniques have already had a big influence on a lot of different scientific study domains. Although eDNA from Arctic earth cores has revealed the former ranges of mammoths and other ice period species, archaeologists are utilizing eDNA discovered in cave dirt to get insight into the past populations of humans.
The blind golden mole was discovered using eDNA, 87 years after wildlife specialists believed the species had gone extinct. This approach is being applied in conservation.
In order to identify and monitor illnesses like Covid-19 in human populations, comparable methods are employed to collect eDNA samples from sewage.
Although she was not engaged in this research, Elizabeth Clare, a professor in the biology department at York University in Ontario, Canada, who oversaw one of the 2022 studies on eDNA collection, said she thought the notion of utilizing spiderwebs was fantastic.
Amazingly non-invasive—that is, unless you’re the spider, of course. That it functions doesn’t surprise me in the slightest,” she wrote in an email.
“We are still pursuing eDNA from air sources, and once the techniques are worked out, I think airborne eDNA will be very successful,” she concluded.
Creatures great and small
The size of the animals found in Perth Zoo ranged from the Asian elephant to the pygmy marmoset. They were able to find animals with different lifestyles and behaviors at both locations—the zoo and the Karakamia woodland sanctuary—including the nocturnal species, the arboreal common brushtail possum, ground-dwelling creatures like giraffes, and creatures covered in fur, feathers, scales, and bare skin.
Approximately twice as many species were found in the zoo (61) as in the woods (32). According to the authors, this discrepancy was probably caused by the zoo’s higher animal population, which raised the likelihood of discovery.
The study pointed out that the various kinds of spiderwebs gathered may potentially have an impact on the kinds and amount of DNA gathered.
Further two-dimensional orb webs from the Araneidae and Phonognathidae spider families were gathered by the researchers in the Karakamia woodland region, which is located 50 kilometers (31 miles) from the zoo.
In contrast, the families Desidae and Theridiidae, both of which have tangled, irregular web patterns, accounted for the bulk of webs collected in Perth Zoo.
According to Newton, some kinds of webs can be appropriate for specific kinds of analysis.
He said that many orb spiders “take down their web in the morning and then rebuild them at night,” which enables scientists to collect DNA across a predetermined time frame.
The researchers will then compare spiderwebs to other materials, such as dirt and water, that may also absorb or gather eDNA.
“I believe that how far the DNA is traveling is a big unknown for a lot of (this).”