eDNA from the Spider-Verse

Explanation: Spider webs are amazing targets! Or, perhaps more apt, amazing catchers. Flying prey get stuck, glued, gummed, coiled, and render mostly immobile, or at least "imflyable" (sorry, my coinage) when encountering a web.

Beyond being a great help to spiders for securing meals, recent research (Xu et al. 2015)) has revealed a wonderful value of spider webs to biodiversity researchers. It turns out that the DNA of prey species, and other species, can get left behind in the web. Then, researchers can conduct what is called noninvasive genetic sampling of that DNA (known as environmental DNA, or eDNA) from the web, and determine what species were encountered.

The process entails sequencing mitochondrial DNA from webs, that identify not just the insect prey species, but the spider species itself. And not just that, recent work (Newton et al. 2024) has shown that web-extracted eDNA can be identified from fauna (vertebrates), too, not just from spiders and insects (invertebrates ). And also, from both native and non-native fauna!

All this means is that spider webs can be a valuable tool and source for determining presence and monitoring of species, invertebrate and vertebrate alike, which can be particularly important for tracking non-native, introduced species of potential conservation concern. And it shouldn't matter which species, and what web design, is being used.

Who knew that the spider-verse would open up such new (research) worlds and be so valuable?

Additonal: The spider featured in the image above is one we previously visited, here in Bali, Indonesia: an arrow spider known as the spiny orbweaver. I don't know if the spider web eDNA approach has been tried there, or with this species, but I suspect it should be universally applicable. Hmmm, that particular web and others nearby probably have some of my own DNA attached. So I would be tagged as an invasive faunal species.
And I now view a video I posted a while back of a Willow Tit (a bird) feeding on prey caught in a spider web ... and am wondering if some DNA from the bird was also left behind and could be identified!

Information:
     Newton, J.P., P. Nevill, P.W. Bateman, M.A. Campbell, and M.E. Allentoft. 2024. Spider webs capture environmental DNA from terrestrial vertebrates. iScience 27(2):108904. DOI: 10.1016/j.isci.2024.108904.
     Xu, C.C.Y., I.J. Yen, D. Bowman, and C.R. Turner. 2015. Spider web DNA: a new spin on noninvasive genetics of predator and prey. PLOSOne 10(11):e0142503. https://doi.org/10.1371/journal.pone.0142503.

EPOW - Ecology Picture of the Week