A research team led by UC Davis has discovered the reason for zebras’ black and white stripes. Possible purposes for the stripes have included camouflage, reducement of heat, social function, disruption of attack by predators and avoidance of biting flies. The results of the study, published April 1 in the online journal Nature Communications, revealed that biting flies are the cause for zebras’ stripes, as flies are likely to avoid black and white-striped surfaces.
The team made the discovery by using a geographic analysis that had never been used before. The team first looked at the seven species of zebras, horses and asses, scoring different parts of their bodies to see how striped they were. The team compared the geographic regions of these animals with variables such as temperature and likeliness of large predators in the area. They then looked at the overlapping of the striped animals and these variables.
“The one that popped out is always biting flies where there is a greater amount of overlap with a greater amount of striping,” said Tim Caro, the lead author of the research as well as a UC Davis professor of wildlife biology. “We never found any significant associations between the other variables and striping.”
“It was a multi-pronged approach,” said Hannah Walker, who graduated from UC Davis this past December as a wildlife, fish and conservation biology major with a minor in Spanish. “This is the one that had the most support.”
It is believed that zebras, as opposed to other mammals, developed stripes because their hair is shorter, thus making them more vulnerable to biting flies than other mammals are.
This discovery also shows how undergraduates can become involved in research.
“Winter Quarter of junior year I took one of his classes,” Walker said, who worked on research for the project during her time as an undergraduate. “The beginning of the next quarter I just asked him if he needed help with research. I’ve been with it ever since.”
Walker’s involvement in the research included doing most of the measurements of zebra pelts and other African animal pelts at museums in Los Angeles, Berkeley and Chicago. She also researched many of the diseases caused by the flies and also helped compile the table in the study published in Nature Communications.
Caro said that Walker’s involvement is a prime example of the opportunities undergraduates have to become involved in research.
“Undergraduates can get involved in research if they take the plunge and ask a professor,” Caro said.
The team’s finding proves that funding is not always key to a project’s success, as Caro’s team received no funding. Rather, Caro said that his team pursued their research because they found the topic interesting.
“We didn’t get funded for this,” Caro said. “Large grants aren’t necessarily the key to doing high-profile scientific projects.”
UC Davis students, in addition to the scientific community, are interested in the research team’s discovery about zebra stripes.
“This is a very exciting discovery,” said Regina Wang, a first-year animal science major. “I have never seen anything about why zebras have their trademark black and white stripes, so this is a very interesting discovery. As an animal science major, it is always wonderful to learn new facts about the animals in our world.”
Now that Caro’s team has discovered why zebras have stripes, other scientific questions can be researched, such as why biting flies avoid striped areas, an answer still unknown to scientists.
ALYSSA VANDENBERG can be reached at campus@theaggie.org.
