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Zebra stripes not for camouflage, new study finds
Monday, January 25, 2016
Monday, January 25, 2016
If you’ve always thought of a zebra’s stripes as offering some type of camouflaging protection against predators, it’s time to think again, suggest scientists at the University of Calgary and UC Davis.
Findings from their study were published Friday, Jan. 22, in the journal PLOS ONE.
“The most longstanding hypothesis for zebra striping is crypsis, or camouflaging, but until now the question has always been framed through human eyes,” said the study’s lead author, Amanda Melin, an assistant professor of biological anthropology at the University of Calgary, Canada.
“We, instead, carried out a series of calculations through which we were able to estimate the distances at which lions and spotted hyenas, as well as zebras, can see zebra stripes under daylight, twilight, or during a moonless night.
Melin conducted the study with Tim Caro, a UC Davis professor of wildlife biology. In earlier studies, Caro and other colleagues have provided evidence suggesting that the zebra’s stripes provide an evolutionary advantage by discouraging biting flies, which are natural pests of zebras.
In the new study, Melin, Caro and colleagues Donald Kline and Chihiro Hiramatsu found that stripes cannot be involved in allowing the zebras to blend in with the background of their environment or in breaking up the outline of the zebra, because at the point at which predators can see zebras stripes, they probably already have heard or smelled their zebra prey.
“The results from this new study provide no support at all for the idea that the zebra’s stripes provide some type of anti-predator camouflaging effect,” Caro said. “Instead, we reject this long-standing hypothesis that was debated by Charles Darwin and Alfred Russell Wallace.”
New findings
https://www.google.com/search?q=zebra%27s+stripes+provide+an+evolutionary+advantage+by+discouraging+biting+flies&ie=utf-8&oe=utf-8
If you’ve always thought of a zebra’s stripes as offering some type of camouflaging protection against predators, it’s time to think again, suggest scientists at the University of Calgary and UC Davis.
Findings from their study were published Friday, Jan. 22, in the journal PLOS ONE.
“The most longstanding hypothesis for zebra striping is crypsis, or camouflaging, but until now the question has always been framed through human eyes,” said the study’s lead author, Amanda Melin, an assistant professor of biological anthropology at the University of Calgary, Canada.
“We, instead, carried out a series of calculations through which we were able to estimate the distances at which lions and spotted hyenas, as well as zebras, can see zebra stripes under daylight, twilight, or during a moonless night.
Melin conducted the study with Tim Caro, a UC Davis professor of wildlife biology. In earlier studies, Caro and other colleagues have provided evidence suggesting that the zebra’s stripes provide an evolutionary advantage by discouraging biting flies, which are natural pests of zebras.
In the new study, Melin, Caro and colleagues Donald Kline and Chihiro Hiramatsu found that stripes cannot be involved in allowing the zebras to blend in with the background of their environment or in breaking up the outline of the zebra, because at the point at which predators can see zebras stripes, they probably already have heard or smelled their zebra prey.
“The results from this new study provide no support at all for the idea that the zebra’s stripes provide some type of anti-predator camouflaging effect,” Caro said. “Instead, we reject this long-standing hypothesis that was debated by Charles Darwin and Alfred Russell Wallace.”
New findings
https://www.google.com/search?q=zebra%27s+stripes+provide+an+evolutionary+advantage+by+discouraging+biting+flies&ie=utf-8&oe=utf-8
13 replies
= new reply since forum marked as read
= new reply since forum marked as read
They're still cute as hell.
Why do Zebras have stripes? Scientists claim to have the answer
http://www.telegraph.co.uk/news/earth/wildlife/10737443/Why-do-Zebras-have-stripes-Scientists-claim-to-have-the-answer.html
The study, published in the journal Nature Communications, mapped the geographic spread of seven different species of zebras, horses and asses and their subspecies and recorded the thickness, location and intensity of their stripes on several parts of the body.
It compared the animals’ geographic reach with other variables such as woodland habitats, the range of predators, temperatures and the numbers of ectoparasites such as tsetse flies.
After examining where the striped animals and variables overlapped the scientists ruled out all but one of the existing explanations, that of avoiding blood sucking flies.
"I was amazed by our results," said Prof Caro.
"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."
While the distribution of tsetse flies in Africa is well known, the researchers did not have maps of tabanids which include horseflies and deer flies so they mapped locations of the best breeding conditions for these insects.
They found that zebra striping was highly associated with several consecutive months of ideal conditions for tabanid reproduction.
Unlike other African hooved mammals living in the same areas as zebras, zebra hair is shorter than the mouthpart length of biting flies making them particularly susceptible to these insects, the team found.
The "Sweet Itch Zebra Rug" with Zebra-like stripes prevents equines from being bitten by the offending small biting flies and repels the bigger, aggressive horse flies by the confusing zebra stripe proven by scientists to keep them away.
