A research team led by UC Davis scientists has helped solve the riddle of why zebras have stripes.
Using systematic scientific methods, researchers determined that horseflies and tsetse flies have been the determining factor for why zebras have their distinctive pattern, according to the study published Tuesday in the online journal Nature Communications.
Previous experiments have shown that the flies tend to avoid black-and-white surfaces, although it’s not exactly known why.
The UC Davis team mapped the distributions of seven different species of zebras, horses and asses, noting the thickness, locations and intensity of stripes on their bodies, according to a university press release.
After ruling out other possibilities for why zebras have stripes, such as for camouflage, the scientists narrowed the reason to one: to avoid blood-sucking flies.
“Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies,” said Tim Caro, a UC Davis professor of wildlife biology.
Researchers didn’t have good maps for tabanids in Africa, the pesky horseflies and deer flies that can torment a hooved creature to distraction. So they mapped the spots that provided the best breeding conditions for tabanids.
They found that striping on zebras is associated with several consecutive months of very good tabanid reproduction conditions.
The question occurred to scientists as to why zebras have stripes and other hooved African creatures do not. The study found that, unlike other hooved mammals living on African savannas, zebra hair “is shorter than the mouthpart length of biting flies, so zebras may be particularly susceptible to annoyance,” according to a press release.
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