One Gazelle or Two?

Mountain gazelle (probably)

According to the International Union for the Conservation of Nature, there are sixteen living species of gazelle. However, as I've mentioned before, counting species isn't always as simple as we might like to think, because the lines between them often blur. Are those two, similar-looking, animals separate species, or just two subspecies of the same thing? And how would we know?

You might suppose that the answer is something along the lines of 'do they cross-breed to produce fertile offspring or not?' Horses and donkeys are different species, you might think, because, while they can interbreed, the result is a sterile mule. Similarly, tigers and lions can also cross-breed, but the results are usually infertile. (Actually, fertile mules and "ligers" do exist, but they seem to be rare). If they don't cross-breed at all, of course, the answer is even simpler. So, take the two gazelles you're wondering about, mate them, and see what happens. Right?

Well, not really. For one thing, that's much easier said than done, especially if one of the possible species is endangered. It's hard enough getting pandas to mate with other pandas to be sure that mere lack of mating proves anything at all. Not only that, but there are, believe it or not, a number of cases where animals that are clearly different species can, indeed, interbreed to produce fertile offspring. Polar bears and grizzly bears, for instance, to give one example becoming more common of late.

A New Species of Dolphin

Common bottlenose dolphin

On September 14th, the discovery a new species of dolphin, the burrunan dolphin (Tursiops australis) was officially announced. There has already been a fair bit of coverage of this in the media (see, for example, the BBC story), but I want to focus here on how this all came about. How exactly do you go about naming a new species?

In theory, it's a fairly straightforward, if somewhat laborious, process. You find your new species, write up a description of what it looks like, and how to tell it apart from similar species, designate a holotype (more on this later), think up a name, and get it published. Leaving aside the difficulty of the first part of that - "first, find your new species" - that's often all there is to it. But, with dolphins, the story has been rather more complicated than that.

First, let's get our bearings. The sort of dolphin we're talking about here is a bottlenose dolphin, a particularly well known type, and commonly seen in sea mammal parks, where they have been trained to perform a number of tricks. They live in every ocean, avoiding only the very coldest of polar seas and are therefore extremely widespread.