About a month ago (!) I decided to start putting up pictures of the dragons I study, sorting them into the habitat groups originally described by Greer in the 1980's. This is a useful way to think about the dragons because, according to their evolutionary relationships, there are two phylogenetically conserved clades of each habitat group: two groups of vegetation-dwellers, two groups of rock-crevice dwellers and two groups of burrowers. By going through these groups one-by-one, it gives me a nice way of posting some lizard pictures, some habitat pictures, and breaking it all up into decent-sized chunks.
Let's start with a small group. This is the small group of rock dragons, with only two species. They also, despite being each other's closest living relatives, look almost nothing alike.
Ornate Dragon (Ctenophorus ornatus)
Ornate dragons are colourful - the ones we were catching looked almost purple, especially the males - intricately patterned and extremely laterally depressed. These were the flattest out of all the species we chased. They used their particular flatness to wedge themselves into the most impossibly narrow crevices in the granite rocks on which they lived. Granite weathers in this peculiar way where the water trickles just underneath the outmost surface of the rock, creating "exfoliations" that are rather like dissecting an onion one layer at a time. The very very narrow crevices created by the exfoliations are the primary means of shelter for these dragons, making them very difficult to catch.
Ornate dragons are incredibly common on granite outcrops in southwest Western Australia. Their ubiquitousness has made them a model organism for studying optic regeneration in lizards. In any animal, if you sever the optic nerves that connect the eyes to the brain the animal becomes blind. This is despite the animal still having fully functional eyes and fully functional vision-processing brain regions. In mammals, this blindness is frustratingly permanent as the optic nerves don't regenerate, leaving the eyes permanently disconnected from the brain. In lizards, however, the optic nerve does regenerate, reconnecting the eyes with the brain. But here's the weird part: the lizard never regains its vision, despite the reconnection, and eventually the connection degenerates again. How very, very strange. Unlocking the mechanisms behind the reconnection, and trying to figure out how to get vision up and running again in these lizards may be the first step to helping people with this particular form of blindness get their sight back.
Ring-tailed Dragon (Ctenophorus caudicinctus)
Ring-tailed dragons look more like what I think of as a standard, normal-looking dragon compared to the ornate dragons. For example, they have square heads and are not particularly flat. Yet they still live in rocky areas and shelter in rock crevices. The rocky outcrops they live on, however, seem to weather into liftable-sized chunks rather than large, flat exfoliations, and as a result the crevices they shelter in are not nearly as narrow. That's because, at least where we were looking for ring-tails, they live on rocky outcrops made of sandstone instead of granite. This makes them quite easy to catch, but it turned out during my fieldwork that though catching ring-tailed dragons was not an issue, finding them was.
Ring-tailed dragons occupy a huge swath of central and western Australia, and I used to think of them as being quite common. They're the only species of Ctenophorus I'd seen before starting this PhD. That's because they're very easy to find in Watarrka and Kakadu National Parks, two very popular vacation spots I visited as a tourist in 2005. So when we started my fieldwork in 2012, I was not expecting to have a problem finding them. It turns out, however, that ring-tails are not so easy to find outside of national parks. We scoured rocky outcrops, struggling to come up with any dragons. We did eventually find all the lizards we needed for my project, but it took a heck of a lot longer than I was expecting, and we spent a lot of time driving huge distances checking out possible locations. It's extremely hot out there, and spending all day scrambling over rocks, searching for tiny brown lizards that you just can't find, is pretty disheartening. When we did start finding them, we got pretty excited:
