I pointed out that this wasn't a Rudyard Kipling story but that many of the explanations had strong ties to just-so stories. I noted that everyone just assumed that there had to be an adaptive explanation for zebra stripes so they kept looking and looking. Every time one of the adaptive explanations was ruled out, they invented another one.
The best explanation back in 2012 was that zebra stripes evolved to protect zebras from horseflies and there was some experimental support for the idea that horseflies tended to avoid stripes. However, there was no evidence that avoiding some horseflies actually conferred enough selective advantage to drive the evolution of stripes.
Now we have a press release that announces the final solution: Scientists solve the riddle of zebras' stripes.
Why zebras have black and white stripes is a question that has intrigued scientists and spectators for centuries. A research team led by the University of California, Davis, has now examined this riddle systematically. Their answer is published April 1 in the online journal Nature Communications.Sounds like old news to me. And I'm still not convinced that you need an adaptive explanation.
The scientists found that biting flies, including horseflies and tsetse flies, are the evolutionary driver for zebra's stripes. Experimental work had previously shown that such flies tend to avoid black-and-white striped surfaces, but many other hypotheses for zebra stripes have been proposed since Alfred Russel Wallace and Charles Darwin debated the problem 120 years ago.
Here's the paper ...
Caro, T., Izzo, A., Reiner Jr, R.C., Walker, H. and Stankowich, T. (2014) The function of zebra stripes. Nature Communications 5, Article number: 3535 [doi: 10.1038/ncomms4535]
Despite over a century of interest, the function of zebra stripes has never been examined systematically. Here we match variation in striping of equid species and subspecies to geographic range overlap of environmental variables in multifactor models controlling for phylogeny to simultaneously test the five major explanations for this infamous colouration. For subspecies, there are significant associations between our proxy for tabanid biting fly annoyance and most striping measures (facial and neck stripe number, flank and rump striping, leg stripe intensity and shadow striping), and between belly stripe number and tsetse fly distribution, several of which are replicated at the species level. Conversely, there is no consistent support for camouflage, predator avoidance, heat management or social interaction hypotheses. Susceptibility to ectoparasite attack is discussed in relation to short coat hair, disease transmission and blood loss. A solution to the riddle of zebra stripes, discussed by Wallace and Darwin, is at hand.I'm betting that in five years there will be papers examining the SIX major adaptive explanations and five of them will be ruled out in favor of the latest one.