Why do we see such huge variation in vision in the animal kingdom? Evolution by natural selection is the key. In such a world rich in light, animals that are able to detect visual signals in their specific environments inevitably enhance their survival and reproduction. Predators have evolved high visual acuity and superior colour vision. And in response, prey have evolved colour patterns that decrease the likelihood of being detected by predators, in the form of camouflage.
But yet, many animals don't just find food using visual signals, but also mates. So, colour patterns have also evolved as sexual signals, communicating genetic quality to potential mates or fighting ability to sexual rivals. We only have to look at the beautiful peacock above to remember just how strikingly conspicuous animals can be.
Visual signals obviously play a very important role in the lives of animals. Even humans seem to use visual signals to enhance their reproductive success: for instance, by using 'ornamentation' like lipstick in women and fast cars in men, they signal sexual receptiveness and future paternal resourcefulness respectively (Low, 1979).
Until recently, studies of animal visual signals and colour patterns have used human assessments of colour. If you've read my previous post ("ChuckleVision") you would know by now that there is a wide variation in visual systems throughout the animal kingdom, and humans tend to be pretty inferior in their colour vision capabilities.
So, knowing this, if you were to assess the colour of say, a lizard, which would be more appropriate: seeing it through the eyes of a) a human, b) another lizard or c) a lizard predator?
The correct answers are b) and c). Using human assessments is extremely subjective, and a human has had no impact on the evolution of the lizard coloration, whereas the visual systems of its potential mates and predators have. You would agree with me then, that the correct way to assess animal coloration is objectively and through the eyes of other, ecologically relevant, animals? I hope so.
This is one thing I aim to do in my PhD. My supervisor was one of the pioneers of objective assessments of animal colour through the eyes of other animals (specifically birds). Using spectrophotometry, digital photography and visual computer modelling, this is fast becoming a super-cool way of understanding why animals look like they do.
My study species Podarcis erhardii have colour patterns that may be for camouflage, sexual communication, or even a combination of both. But I'm not going to assess this. Instead, I'm going to look through the eyes of their mates and predators, and tell you what they see.
