Zebras of all stripes repel biting flies at close range
nature.com
nature.com
"Controlled experiments have used various landing substrates, including striped and solid oil tray traps, sticky plastic, smooth plastic, cloth (Experiment 2 in [22]), horse blankets or sheets, and paint on live animals."
Here's an analogy: people often fear and avoid insects that are yellow/black striped, not because the stripes are annoying, but because many such distinctively striped insects have a painful sting, and avoiding the stripes avoids the stinging insects.
The use of "would have to" completely ignores the potential of stripes to be an identifying feature. If my hypothesis were correct, there would not have to be any other selective pressure; since all stripes identify "zebra," any stripes would work.
For example, to test my hypothesis, it might be sufficient to check whether, in those zebras where some of the hide is tan rather than striped, the tan portion of the hide is attacked by the flies disproportionately to the striped portion of the hide.
In sum: the paper reflects on the mechanism of the stripes in repelling flies, and seems to disregard the possibility that the stripes simply allow the flies to identify "not a good target."
You also have experiments like this, where painting Japanese cows in zebra stripes was an effective fly deterrent, even though the flies there have no evolutionary history with zebras. (It's worth clicking just for the photo of the test cow.)
https://journals.plos.org/plosone/article?id=10.1371/journal...
1. It's possible that Japanese flies are repelled for different reasons than African flies. 2. It's possible that flies are repelled both because the stripes interfere with the flies' vision in some way, and because the (African) flies prefer other animals.
Which has lead to suggestions to breed this into livestock. Which will certainly change the landscape in US.
As I said before: Somehow driving through South Dakota looking out over a vast field of seaweed eating, zebra striped cows was not the future I anticipated as a youth.
Maybe there would be a decline in population first, then a rise of stripe seeing flies.
Deer, bears, coyote, wolves, raccoons, mice, otters, beaver, rats, muskrats, cougar, bobcats, chipmunks and squirrels, elk and moose, skunks, badgers, porcupines can all be found in nature in the upper midwest, along with various moles, voles, shrew and weasel family members can be found pretty much anywhere outside of a city center.
Since deer fly (and other biting flies) typically need a bit of standing water to breed, they're going to be found pretty much anywhere mammals live. If they decide they don't like striped cows, there's going to be plenty of other options to munch on.
Well done World for funding simple scientific questions - not trying to fix the planet, just asking "why does that happen".
Marvellous
One (morbid) thought - I wonder if lions get bitten less when heads down in a black and white carcass?
I like the introduction section of this paper (basically speculating "How the Zebra Got His Stripes") as a modern descendant correcting some of the misconceptions from Rudyard Kipling's How the Leopard Got His Spots[0].
Especially a tale of an imaginary past when leopards and men had not yet been magically given their recognized colorings at the time.
But Zebra and Giraffe already had the patterns we know today:
Zebra moved away to some little thorn-bushes where the sunlight fell all stripy, and Giraffe moved off to some tallish trees where the shadows fell all blotchy.
'Now watch,' said the Zebra and the Giraffe. 'This is the way it's done. One—two—three! And where's your breakfast?'
Leopard stared, and Ethiopian stared, but all they could see were stripy shadows and blotched shadows in the forest, but never a sign of Zebra and Giraffe. They had just walked off and hidden themselves in the shadowy forest.
'Hi! Hi!' said the Ethiopian. 'That's a trick worth learning. Take a lesson by it, Leopard. You show up in this dark place like a bar of soap in a coal-scuttle.'
'Ho! Ho!' said the Leopard. 'Would it surprise you very much to know that you show up in this dark place like a mustard-plaster on a sack of coals?'
[0]Outdated literature not safe for all audiences, as always. https://www.owleyes.org/text/just-so-stories/read/how-the-le...
"This content stereotypes some peoples or cultures - it was wrong then and now but we are keeping it here as a historical document (and to spark conversation)"
(If you have Disney+ go look for the original Dumbo)
And the latest findings here can be convincing to an extent, but not entirely conclusive.
So as it stands nobody still knows for sure how the zebra got its stripes.
Intuitively, it does seem like stripes would make it more difficult to achieve focus for a compound eye, similar to how when looking through a chain-link fence or window screen it's easy to focus the wrong plane due to the spaced repetition.
You're a lump of electrical fat wrapped in a fortress of bone, running an internal approximation of the localised world outside.
And from within this fortress, with its little holes for light, you control a robot made of meat.
We introduce tree frogs or perhaps geckos or chameleons to live on cows. They would eat the flies and the body heat could probably keep them warm year round.
They’d eventually breed themselves to adapt to the life cycle and be self perpetuating.
As I understand it the fly bites hurt a lot so I’d imagine they’d prefer a lizard but worth testing.
"The best-supported hypothesis for why zebras have stripes is that stripes repel biting flies. While this effect is well-established, the mechanism behind it remains elusive."