02 June 2011

“White and black means set to attack!”


Does this look like a warning?

ResearchBlogging.orgI'm not talking about the pose; I'm talking about the colour. In many species, we associate conspicuous colour with warnings. “Don’t eat me, I’m poison!” Classic example is poison dart frogs.

We almost never talk about “warning colours” in mammals, though. Mammals tend not to have bright reds and yellows you see in invertebrates or reptiles or amphibians. But they certainly can have fur that is... noticeable.

New paper by Stankowich and colleagues tries to look at whether colour in mammals could act as warnings. They had a series of hypotheses that predicted mammals’s fur colour would be related to whether the animal has odor defenses (think skunk) or burrows (think badger), and so on.

The trickiest part of this sort of study is quantifying the colours. The authors classified mammal coats by how much an animal would stand out in the environment. They called this measure “salience”. They admit that these scores are subjective, but their coding scheme was based on previously published research.

They also developed codes for behaviour, body mass, and habitat. Finally, all these measures got tied into a massive set of relationships between the mammals.

Mammals with coats that “popped” (high salience) tended to be stocky burrowers living in open habitats, and also tended to be ones that were able to defend themselves using scents from anal glands, or possibly just by fighting There is a lot of variation in the data, but the authors think that this provides some evidence that colour is an honest signal of defensive ability.

But one of the animals that doesn’t fit with the patterns is... the giant panda. The authors have a reference to another paper suggesting that pandas’ colour might aid in “background matching.”

Maybe that black and white coat is for “stealth mode.”


P.S.—Fun thing I learned reading this paper: There is a real animal called a zorilla. I totally would have guessed that that was a Pok√©mon name. Or from some old monster movie.


“Those fools! They think they can defeat me? Release the zorilla! Bwa-hah-hah-haaaaaaaaaaaaaa!”

Reference

Stankowich T, Caro T, Cox M. 2011. Bold coloration and the evolution of aposematism in terrestrial carnivores. Evolution: In press. DOI: 10.1111/j.1558-5646.2011.01334.x

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4 comments:

namnezia said...

In Spanish, the word for skunk is Zorillo.

"the Dude" said...

Many arboreal primates offer an exception to the black-white warning rule, in that bright red scalps/faces may deter flying raptors. Mandrills, uakaris, orangs, redheaded humans, male gorillas & some female bonobos all have bright red hair patches.

I figure hominoids (after the split with gibbons 20ma) developed red scalps at the same time they developed large canopy nests, fooling large eagles & owls into assuming they were raptor nests. Simultaneously, infant hominoids produced a cooing sound which resembled owls hoo-hoo, and reached out with hooked hands toward any nest visitor (mother or other) resembling the hook beak of a raptor.
DDeden
DDeden

Michael said...

I learned that the critical aspect of warning colors is the contrast, and many predators can't see colors anyway - black and anything light works fine. Colors in actual integument (instead of hair) might be more sunlight-protective than white, though.

Woodlover said...

I recently read an interesting article on the black-and white colouration that is in line with this thought: "To minimize the risk of being attacked by the tiger, the colouration of the giant panda is aposematic, warning would-be predators of its vice-like hug and bite. This warning signal, visible even in poor light, consists of a black-and-white contrast on the face (ears and eyes) as well as the body as a whole.”
The article can befound on:
http://explorebioedge.com/bio-bullets/item/43-warning-colouration-in-the-giant-panda.html