Gary Stab asked:
Is there a metabolic cost to the generation of bright colours in animals?
Itís a very good question and youĎre absolutely right and there are pigments that animals use to attract mates. Thatís generally what itís all about. These are molecules that are quite costly to create. Not to mention the fact that you also look more obvious to things like predators. This was a question that someone, a guy called Geoffrey Hill looked at. Heís from the University in Alabama. He looked at house finches that grow colourful feathers in yellows and orange and reds using carotenoid pigments. Similar to what Dave was talking about earlier. What he did was he actually fed a bunch of house finches with these types of pigments in water. He fed half of these birds lots of food so they were nice and happy and were doing great. The other half he restricted their diets, which wasnít very nice. Basically he wanted to know what the difference was when they did and didnít have enough food to eat. As you might imagine, the ones that didnít get enough food were much more drab than the ones that had lots of food who grew lots of night, shiny colourful feathers. Thatís a really good way of showing to us that yes, producing pigments is expensive in food and if you havenít got enough food to do that then you tend to not be able to produce such brightly coloured feathers.
Gary Staab asked the Naked Scientists: It there a metabolic cost to the generation of bright colours on certain animals? Some birds for instance have brighter breeding colours. Thanks for any help you can give. regards, Gary What do you think? Gary Staab, Fri, 25th Apr 2008
Can't see why there would be. There may be a risk in some case in higher predation (rather depends on the animal - in many species, bright colours are a warning of poison, and so may help against predation).
I suspect that there would be, although it probably depends on how the bright colors are created. Bright colors in some animals are due to pigments, whereas others are due to certain optical effects caused by microstructures (as in certain butterflies). In birds, both forms are known.