Run Gecko Run (Don't Ever Look Back)

How do scientists study running performance? Well, with humans we'd take subjects out onto a track and measure how fast they could sprint between two points.

With geckoes?

It's pretty much the same. Except we have
to design a track that encourages the gecko to move as quickly as it can in a straight line. (Because geckoes aren't as good at taking verbal directions as humans are ... )

Skye's current experiment is based around this running track. She puts a gecko into the near end (as shown in the top photo) and then chases it down the track with a foam paddle. Don't worry, the gecko's fine - the paddle is just to prevent it from stopping or turning around or anything that might disrupt measurements.

As the gecko runs down the track (away from us, in this picture), it passes the 4 light sensors that help Skye to accurately record the gecko's speed. Skye repeats the run 3 times more, so that she can get the gecko's fastest performance (best of 12 time splits - 3 trials x 4 sensors).

After measuring running performance, Skye takes the weight of the gecko to account for its body size in her calculations. This is because larger geckoes will be able to run faster independently of temperature.

Then, the gecko returns to its home in the lab.

Each gecko completes 8 running trials at temperatures between 15 and 38 degrees Celcius. Some populations won't ever have seen some of these temperature extremes in the wild (and others will have). 

Skye is predicting that where a gecko comes from will affect how it performs at these different temperatures. For example, at low temperatures geckoes from tropical North Queensland should perform more poorly than geckoes from Brisbane - because, in nature, Brisbane geckoes experience low temperatures every year (and tropical geckoes don't). 

Skye's still working hard measuring gecko running speeds ... so we can't tell you any results yet. But watch this space!

Why Temperature Matters to Geckoes

At the moment, Skye's doing a really cool experiment looking at how Asian house geckoes from different environments handle changes in temperature.

Why is this important? Well,
climates are changing. And scientists want to know how species will handle climate change - will they go extinct? will they do even better?

To answer these questions, we have to know more about how species perform across their natural range. Because animals that are already living close to their thermal limits might be at greater risk if things heat up, or even cool down. And because some animals have a greater capacity to rapidly adjust to temperature change (or acclimate) than others. And because most of the animals on the planet are what we call ectotherms, which (unlike humans) can't warm themselves up internally: their digestion, brainpower, muscle activity - everything - is dependent on the temperature in their environment.

So what's Skye doing? She's collected Asian house geckoes from across their latitudinal range in Australia - from Brisbane all the way up to Cape York. (ahem - more traveling??). Geckoes from all these different populations have grown up in quite different environments - but in general, temperatures get hotter and less variable as you head north from Brisbane.

Which leads us to some fundamental questions in thermal ecology: do animals in these different environments become 'experts' at performing under just those conditions? Or can they perform over a wide range of temperatures - just not very well? Is the pattern changeable (suggesting acclimation) or unchangeable (suggesting adaptation)?

Skye is testing these questions by looking at the running performance of geckoes from different populations  - across a range of temperatures. If you've ever watched a gecko on your window at night, you'll see why running is so important to them - it's how they catch prey, but also how they escape from predators and is a key factor in determining dominance of individuals.

So looking at running performance is a great way to assess how temperature affects the geckoes' ability to survive and make babies.

This is just a teaser, really. Letting you know why *some* people spend hours tending to and running geckoes in all sorts of temperatures. In the next post, I'll talk a bit more about the specifics of Skye's study - including her amazing experimental set-up!