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“It suddenly struck me that that tiny pea, pretty and blue, was the Earth. I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn't feel like a giant. I felt very, very small.” – Neil Armstrong (1930-2012)

Fresh Reads from the Science 'o sphere!

Tuesday, March 09, 2010

A Grey Lizard That Isn't Really Grey

Last month, during the Chinese New Year period, I was passing through a jogging track beside a canal in Ghim Moh when I spotted this little critter:


It had a surprisingly deep grey colour that matched the surrounding asphalt very well. If not for the fact that it was dashing across the track right in front of me, I would have missed it.

I think that its grey skin is a good camouflage to protect the lizard against predators, such as birds.

I don't know much about lizards, but I find its even grey tone surprising since I've only seen garden lizards in brown and green.

My first thought when I saw it was - maybe there is a selection pressure for "jogging track lizards" to be grey?

Here's the fellow next to a ten cent coin.

The lizard was about 3 cm long. It could be a juvenile, so the grey colouration could be a transitory feature.

Most scientists who study the evolution of animal features tend to focus on the adult form. That doesn't mean that the features of young animals are less important.

We must remember that the environment starts to act against an animal, even before it was born!

If an animal cannot survive its youth, it cannot become an adult.

When I took a close-up photo of the lizard, I realized that it wasn't really grey!

The scales were in a mottled pattern of light and dark brown, and coupled with the fact that the lizard appeared to be moulting, the resultant colour from a distance was a dull, dark grey.

It made me ponder about the concept that quantitatively different features at the component level can result in qualitatively different features at the system level, ie. emergence.

After all, if you try to find a novel "grey gene" on this grey lizard, you might end up finding nothing! It might have been the combination of expression level changes to existing brown colour genes and opacity of the scales that contributed to its overall grey appearance.

Well, that's too much speculation for one day.

So I left the lizard, which had remained frozen in that position for minutes on the asphalt and didn't leave even after I had walked several metres away.

Survival instinct or excessive fear?

Seconds later, a bicycle zipped by that same spot.

I didn't look back.

Would you like to know more?
- Tertiary color (Wikipedia)