Sunday, 25 August 2013

Welcome, the Olinguito

If you follow any sort of science news site, especially if you read the zoology bits, you cannot have failed to notice the recent announcement of the discovery of a "new species of carnivore" in South America. By the standards of such things, its a major news story - the last time this happened in the New World was in 1978, when the Colombian weasel was discovered. In addition to the news coverage, the original announcement is available to read (all 83 pages of it), free online, for anyone who cares to. There's probably not a lot I can add to all that.

Still, I feel that it's not something I should really ignore, so here's my take on it, and an attempt to put the discovery into some sort of context.

Let's start with the obvious: what is this new animal, exactly? The olinguito (Bassaricyon neblina) is a newly described species of olingo. Which may, in many people's minds, raise the question: "um... what's an olingo?"

Olingos are long-tailed, tree-dwelling, members of the raccoon family, found in the jungles of Central and South America. They were first scientifically described, as a group, by the American zoologist J.A. Allen in 1876, which is itself remarkably late (all the other main groups within the family had been discovered by 1830, and most of them well before that). They've never been seen to eat anything but fruit and flowers, although it's suspected that they also snack on the occasional passing insect.

Which may not be most people's idea of a "carnivore". One can't blame the journalists here; a "new species of carnivore" is exactly the phrase used by Kristofer Helgen and co-workers in the original paper. But what they mean by "carnivore" is not the lay-person's understanding of the term: this is not an animal that eats meat. Rather, its a member of the order Carnivora, a group of mammals that includes a great many meat-eating species. This is the group that includes such things as cats, dogs, seals, and weasels, all of which are good examples of carnivorous mammals. But it also includes bears and raccoons, which are really rather omnivorous, or, as in this case, outright herbivorous.

So it's a "carnivore" in the same sense that a giant panda is. Perhaps a word like "carnivoran" would be more accurate... if rather more opaque to most non-zoologists.

Just how common is it to discover a new species of animal, anyway? The short answer to that is "very". The formal announcement and scientific naming of the olinguito was made in the journal ZooKeys. It's a journal that specialises in this sort of thing, and it isn't even the only one. That's ignoring the fact that you don't have to publish new species in such narrowly specialised journals. But let's, for the sake of it, just look at that one journal.

The paper was published on the 15th August, which, as I write this, was ten days ago. In the time since then, ZooKeys has published the descriptions of a further twenty two newly discovered species of animal. And, no, it's not some sort of special season when they rush loads of descriptions out - this is normal.

Mind you, none of them are quite as large and seemingly obvious as the olinguito. One is a beetle, one is a fly, one's a spider, and a fourth is an almost microscopic crustacean. The other eighteen - all from the same paper - are millipedes. A good week for millipede research then, but it makes the point that the overwhelming majority of new animal species discovered are invertebrates.

If we ignore all of those, then most of the recently discovered species of vertebrate are fish, and there's doubtless a heck of a lot more of them out there that we haven't found yet. We haven't really explored all that much of the oceans, and a small fish living far from land is a pretty easy thing to hide, even if it lives near the surface, which many of them don't.

So, okay, just mammals, then. How common is the discovery of a new mammal? Again, not so unusual as you might think. Consider that, in the three years I have been writing this blog, I've already written full-length posts on two newly discovered species, not counting this one. As well as shorter posts on a number of others.

Take a look through those posts, and you'll notice some common themes. The best place to hide a new species of mammal is the jungle, and it's better if it's something small like a mouse or a bat. The jungle is an unforgiving environment for humans, and there's so much foliage that something can be almost right in front of you without you seeing it. That's assuming it even comes out of hiding during the day - if it's nocturnal, your job is even harder. After the jungle, perhaps the second best place to hide a new mammal is the sea, for much the same reason that it's a good place to hide new fish.

That the olinguito lives in the cloud forests of the Colombian and Ecuadorian Andes is, then, perhaps not so much of a surprise. If you're going to find a new species of large (ish) mammal, then up a tree in a remote mountainous jungle far from civilisation is exactly the sort of place you should be looking.

The raccoon family
But, anyway, what do we mean when we say that the olinguito is a "newly discovered" species? For one thing, what happened last Thursday was that the official description and name of the new species was published. The olinguito was actually discovered three years ago, and I even bought a book recently that mentions it -  describing it as an unnamed species of "Andean olingo".

But, even allowing for that, it's not as we'd never seen one before 2010. We just hadn't realised what it was.

There was some difference of opinion among zoologists about how many species of olingo we knew about before the discovery of this latest one. Answers ranged from one to five, although a common scheme argued that there were just two: a northern species in Central America, and a southern one in South America.

One of the reasons the olinguito is a big deal is that the Carnivora are probably just about the best studied order of animals of any kind. We have a better understanding of their evolutionary relationships, number of species, and so on, than we do of almost any other similarly sized group. But even then, in this remarkably well-studied group, there are holes.

These particularly include the smaller, tropical species. Olingos are obviously one example, but one could just as well point to such animals as grisons, hog badgers, and some of the weird stuff on Madagascar (falanoucs, for example). What Helgen and co-workers did in their study was to examine a range of raccoon-like animals from across the region, genetically, physically, and geographically, to determine how they were related.

They made a number of important findings. They confirmed, for example, that olingos are actually a thing - a particular kind of animal that descends from a common ancestor, and that are more closely related to one another than they are to anything else. According to their estimates, the first olingos appeared between 10 and 8 million years ago, during the late Miocene, and their closest living relatives are the coatis - omnivorous, long-nosed, raccoon-like animals found from Arizona to Uruguay. The first part wasn't a great surprise, but the second was rather more so, since the prehensile-tailed kinkajou had previously been fingered as the olingos' closest relative.

For that matter, they also confirmed that the raccoon family really exists as an entity, diverging from the weasel family between 20 and 30 million years ago, probably in northern Central America. More significant, of course, was what the genetics told them about the number of olingo species. They identified four. The northern olingo we already knew about, while the previously known southern olingo turned out to represent three different species. One (by definition) was the "real" southern olingo, while another was already known to be at least a subspecies, and had, indeed, been identified and named as a possible full species back in 1909.

The other one, of course, was the olinguito, and, perhaps surprisingly, nobody had ever suspected it was anything different before.

Since the olinguito lives in the high Andes, and the other two don't, the authors recommend re-naming them "lowland" olingos, rather than merely "southern". That suggestion has no official standing, and the existing scientific names won't change, but there is some logic to it, and I won't be surprised if it's more widely adopted.

Indeed, it turns out that the olinguito is perhaps the most distinctive of all the olingos, being, for example, the smallest. Its ancestors separated from the rest of the group around 4 million years ago, as a chain of islands began to form in what is now the Panamanian isthmus. Northern and lowland olingos only diverged around 2 million years ago, when the island chain became a continuous land bridge, and the two kinds of lowland olingo separated not long after. There also appear to be at least three, and probably four, subspecies of olinguito, living in different parts of the mountain chain - one of which, the red olinguito, is particularly distinctive.

Despite this, it turns out that we actually had at least one olinguito in a zoo. Or rather, in several zoos, since she'd been moved around from one to the other in the hope that she'd finally find a partner she was willing to mate with. It's now, in retrospect, rather obvious why that never worked - none of her prospective partners belonged to the same species!

(Some of the news reports imply that this was how the olinguito was discovered, but that's simply not the case. She was identified only after we knew olinguitos existed, but before we had a formal name for what they were).

So, the world has a new kind of olingo, the first new carnivoran to be discovered in the western hemisphere since 1978. Should we expect more new species of mammal to be found, perhaps even large and interesting ones? You can count on it.

[Photo by Mark Gurney, released under Creative Commons Licence 3.0. Cladogram adapted from Helgen, et al, 2013]

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