In the midst of our 2020 continuing chaos – right around November’s election season in the United States, to be exact – headlines sprouted up all over exclaiming: “Scientists discover two new marsupial species in Australia” and “Drop everything and look at these newly discovered glider species from Australia!” All of these pieces extolled the new discovery of a creature one might expect to find in the stuffed animal aisle of your local toy store (as evidenced by the video below).  

While this animal appears to be closely related to the Furby™️, it actually has more in common with koalas. Like koalas (and most of Australia’s native mammals), the greater glider is a marsupial that grows to maturity in a pouch after being born. They also share the dietary preferences of koalas, feeding almost exclusively on eucalyptus [1]. Greater gliders have specialized microbe communities in their guts to help them digest the long, fibrous eucalyptus leaves. Unlike koalas, however, these gliders are nocturnal (i.e. active at night) and as their name suggests, they also glide from tree to tree as they strip leaves and bark for food.

As I saw the click-bait headlines about these “newly discovered” animals, I couldn’t shake my disbelief.  How was it possible that there is some corner of the earth still untouched, still mysterious enough where we humans could still be “discovering” charismatic megafauna? My disbelief was warranted; it turns out that the “discovery” which articles were leveraging for clicks is much more nuanced. The original scientific journal article puts it more directly: “Genetic evidence supports three previously described species of greater glider”.  In essence, researchers used genetic tools to find out that what was once believed to be one species (Petauroides volans) is now delineated as three separate species (P. volans, P. armillatus, and P. minor) [2].

Instead of trekking through Australian bush to stumble upon new flying gliders (though certainly some trekking was required to get DNA samples), the researchers at James Cook University uncovered most of their discovery in labs and behind computers, where they analyzed the details of glider genomes.  A few years prior, other scientists had predicted that the greater glider was likely more than one species, based on physical differences like coat color and body size, as well as geographical locations. Now, the team from James Cook University aimed to test this hypothesis with genetic tools, an increasingly-common way of defining species in the modern era.

However, there was an issue. The greater glider did not have a genome sequenced. Genome sequencing, which reads out every piece of DNA in an animals’ cells to the letter, is becoming cheaper each year, but most animals do not have sequenced genomes (yet). Rather than shell out the dollars to sequence multiple genomes, the researchers used a work-around.  Diversity Array Technology (DArT) allows scientists to look at many parts of the animals’ DNA that may differ, without using a sequenced genome to know where to look [4]. Using the DArT method, the researchers found that the genetic profiles of gliders across their range were quite different – so different that they were likely not mixing with each other, and the genetic differences aligned with the physical differences other naturalists had observed [3]. With this evidence, the team claimed that the species should be split into three. Thus, two new species suddenly entered the tree of life; they were “discovered.”

While splitting one species into three might seem unimportant, these distinctions have implications for conversation. For instance, now that the single species has become three, the relative geographical ranges for each are much smaller. This increases concern for the species’ habitat loss and population numbers, especially in the wake of one of the worst Australian bushfire seasons in history (and yes, that was actually in 2020) and commercial logging [3].

Reading this study left me with the question: what does it really mean to “discover” something as large as a mammal in the 21^st century? I understand why those tempting headlines garnered clicks; so many of us, unable to travel in the midst of a global pandemic, yearn for the romanticized eras of globe-trotting naturalists like Darwin in the Galapagos, Wallace in the tropics, Audubon across the Americas. We wish to armchair adventure, hoping for wild mysteries despite our globalized world.  However, one of the largest uncharted territories in biology is the genome. In it, there is plenty of mystery still to discover, lingering in the chromosomes of creatures great and small, strange and stuffed-animal like. We will just have to adjust our romantic vision slightly and be willing to trade some of the khaki for lab coats and the binoculars for bioinformatics.

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References:

1. Comport, S. S., Ward, S.J., and Foley, W.J. (1996). Home ranges, time budgets and food tree use in a high density tropical population of greater glider, Petauroides volans minor (Pseudocheiridae: Marsupialia). Wildlife Research 23: 401-419.
2. James Cook University (2020). Greater glider species triple. 9 November 2020.  Available at: https://www.jcu.edu.au/news/releases/2020/november/greater-glider-species-triple  (Accessed: 1 December 2020).
3. McGregor, D.C., Padovan, A., Georges, A., Krockenberger, A., Yoon, H. & Youngentob, K.N. (2020). Genetic evidence supports three previously described species of greater glider, Petauroides volans, P. minor, and P. armillatus. Scientific Reports 10:19284.
4. Wenzl, P., Carling,J., Kudma, D., Jaccoud, D.,Huttner, E., Kleinhofs, A., Killian, A. (2004) Diversity Arrays Technology (DArT) for whole-genome profiling of barley. Proceedings of National Academy of Sciences, 101 (26) 9915-9920.

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[Edited by Meredith Lutz]