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Zebras’ stripes discourage biting flies from landing

theatlantic.com

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Re: Zebras’ stripes discourage biting flies from landing

#21

Post by ARandomerDude »

atoav wrote: post #20

Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…

> the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival

From the article:

> Amanda Melin of the University of Calgary recently showed that lions and hyenas can’t even make out the stripes unless they get very close.

Re: Zebras’ stripes discourage biting flies from landing

#22

Post by thethirdone »

darpa_escapee wrote: post #15
gpderetta wrote: post #4

https://en.m.wikipedia.org/wiki/Dazzle_camouflage

The study in the article tested this hypothesis and refuted it.

It in fact did not test anything about dazzle camouflage. The study [1] (linked by the linked article) did test how predators vision works and determined that Zebras camouflage doesn't serve much purpose at long ranges, but doesn't prove anything about shorter ranges where dazzle camouflage may make it easier for zebras to run away because predators aren't following them accurately.

[1]: https://journals.plos.org/plosone/article?id=10.1371/journal...

Re: Zebras’ stripes discourage biting flies from landing

#23

Post by gridspy »

atoav wrote: post #20

Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…

While you raise a good point about evolution being inscrutable - the stripes do effect files...

" By watching and filming the stable’s horses and zebras, the team confirmed that horseflies were much worse at alighting on the latter. The flies had no problem finding the zebras or approaching them, but couldn’t stick the landing. “You get a quarter as many landings,” Caro said. “The flies just can’t probe for a blood meal with the zebras.” "

I think the evolution angle relates to the question "Why did this trait evolve? What function does it serve?" with a potential Answer "It repels flies."

Re: Zebras’ stripes discourage biting flies from landing

#24

Post by gridspy »

The most interesting parts (to me):

"By watching and filming the stable’s horses and zebras, the team confirmed that horseflies were much worse at alighting on the latter. The flies had no problem finding the zebras or approaching them, but couldn’t stick the landing. “You get a quarter as many landings,” Caro said. “The flies just can’t probe for a blood meal with the zebras.”

“When we looked at the videos, we found that the flies simply aren’t decelerating when they come in to the stripes,” Caro said. Either they miss and overshoot the zebras, or they bump into the hides and bounce off. Something’s clearly throwing them off, but the details are still a mystery. Caro said that they might treat the black stripes like a pair of trees, try to fly between them, and end up colliding with the white stripes. Alternatively, the stripes might mess with their optic flow—their sense of objects moving across their visual field.

Re: Zebras’ stripes discourage biting flies from landing

#25

Post by drcode »

I think flies can detect carbon dioxide levels to find their hosts (https://journeynorth.org/tm/crane/co2_traps.html)

Why is this fact never mentioned in this article, and did they do any analysis on how wearing a coat can affect CO2 levels around a horse's body?

Re: Zebras’ stripes discourage biting flies from landing

#26

Post by joaomacp »

ta1234567890 wrote: post #11

If the theory of evolution is correct, then there is no why to any animal trait. There's no "reason" for the traits, it only happens that maybe some traits allowed the species to survive longer and so they are still around today, but that doesn't mean "someone" enforced a certain trait with a certain purpose. So, a more scientifically oriented title should be: What do Stripes do for Zebras? Shoo away flies.

"Why do humans have teeth? To chew food"

Doesn't look bad to me, and it's the same exact point.

Re: Zebras’ stripes discourage biting flies from landing

#27

Post by gridspy »

drcode wrote: post #25

I think flies can detect carbon dioxide levels to find their hosts ( https://journeynorth.org/tm/crane/co2_traps.html ) Why is this fact never mentioned in this article, and did they do any analysis on how wearing a coat can affect CO2 levels around a horse's body?

They did attempt using coats of solid colors with no benefit. This at least is partial testing of your hypothesis.

Re: Zebras’ stripes discourage biting flies from landing

#29

Post by outworlder »

atoav wrote: post #20

Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…

Are flies killing (non-striped) zebras? Or would they make them infertile? Attract predators?

Flies would be messing with the zebras ability to pass on their genes in some for for this trait to be selected for.

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