Snapshot Serengeti Talk

Zebra stripes

  • maricksu by maricksu moderator

    Thank you Tillydad!
    Stripes of zebras are very interesting.
    I am not sure about this, but I recall read somewhere that unborn zebras are black in early stages. Please correct, if I remember it wrongly. But If so, it would be very understandable that they are black with white stripes 😃

    Also the reason for stripes has been explained so many different ways. Maybe a bit true in all of them. Mostly I prefer the heat-regulation-theory and also social meaning of unique pattern in recognition. 😃

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  • tillydad by tillydad moderator in response to maricksu's comment.

    There is strong empirical evidence that embryos are black and this leads to the conclusion that the stripes must be white .

    Many theories have been asserted as to why the zebra should have stripes . The main theories are :

    1 Thermo-regulation

    2 Social recognition/function

    3 Avoidance of biting by flies

    4 Camouflage

    There has been a paper published by Royal Society Open Science which has shown that the most striking, dark contrasts are found in the hottest parts of the plains zebra's ( Equus quagga ) range . This would seem to strongly support the thermo-regulation theory . The contrast between dark and light parts of the coat means that the dark areas heat up more than the light parts which produces a cooling air to flow over the skin of the zebra .

    A study in the Journal of Experimental Biology has shown that horseflies prefer to land on even coloured surfaces rather than striped ones . There is also some evidence that shows that striped equids are more prevalent n areas where there are more biting insects . Both of these points would suggest that the zebra stripes play an important role in avoiding the worst of being bitten by flies .

    Numerous studies have revealed varying results concerning camouflage being a driving force behind the zebra's stripes . There are almost certainly some benefits to them having stripes that confuse predators .

    The evidence is weak for the stripes having a real social function, although it is possible that there are some minor benefits to the zebras having stripes .

    It is a fascinating area of study 😃

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  • davidbygott by davidbygott moderator

    From spending many, many hours hunting with lions in Serengeti, I feel that the only real sense in which zebras are camouflaged is in poor light at distances over about 100m. Then - to us - the stripes blend together to give a flat neutral grey, about the same tone as that of dry grassland. (That's also why so many newbies on SSS are puzzled by distant herds of grey animals 😃) In twilight, where wildebeest and zebra are grazing together, the 'grey' zebra just disappear like magic! So why not just be grey?

    In bushland it's true that stripes may help to break up the shape of a zebra, but if you are close enough to resolve the stripes you are also close enough to hear the zebra, and they are not silent animals - they chomp and rip at the grass, they snort and grunt and fidget, so they are very obvious at close quarters.

    The temperature regulation idea is interesting. I personally like the anti-tsetse fly theory of striping, and there is some experimental evidence for that. Stripe patterns are undoubtedly useful in visual recognition by members of the same social group, particularly in crowded situations where a stallion must be constantly vigilant to keep his mares together, but the same function could surely be achieved by a less flamboyant pattern!

    As a starting point for learning more about the subject of equid coloration, though it's an old publication, I recommend Jonathan Kingdon's "East African Mammals" vol IIIB - he's an artist as well as a scientist and pulls together a lot of scattered information with great graphics too.

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  • tillydad by tillydad moderator in response to davidbygott's comment.

    Personally speaking, both the thermo-regulation and the anti-fly theories are the most likely reason for the stripes . The vicious bites of the tsetse fly would surely be a major reason to develop a regime against it, as would trying to stay cooler on a baking hot day .
    Camouflage and social function seem, to me at least, contrary because if the stripes really aid camouflage then the social function would also be reduced 😃

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  • davidbygott by davidbygott moderator in response to tillydad's comment.

    We could have learned so much from the extinct quagga of the South African Karoo, which had a brown body, white legs and striped forequarters...was it in the process of gaining stripes, or losing them?

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  • maricksu by maricksu moderator

    Big thanks, Tillydad and David for this fascinating and thorough discussion-chain about this topic!
    I am really grateful, that you share all this knowledge, experience and thoughts you have.
    Here is lot to learn and think. I have always admired natures evolution-wisdom, everything has meaning and purpose 😃

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  • WillowSkye by WillowSkye in response to davidbygott's comment.

    Hi @davidbygott, I've got good news for you 😃 Check out the Quagga Revival Project we have here in South Africa. Check out Foal FD15.
    Enjoy 😃

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  • davidbygott by davidbygott moderator in response to WillowSkye's comment.

    Yes, I'd heard of this work - these new quaggas are looking very good! 😃

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  • tillydad by tillydad moderator in response to maricksu's comment.

    Thanks @maricksu for the kind comment . I enjoy sharing what little knowledge I have gained over the years . It is great that we can have discussions such as this and learn from each other I am sure that @davidbygott feels the same way as he shares his extensive knowledge with us all .

    One of the great things about nature is that we still have so much to learn about the animals and it is to be hoped that as we learn we can protect more of this wildlife for generations still to come . To quote Alexander Pope " A little learning is a dangerous thing" and it is therefore important that we all strive to continue to learn 😃

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  • tillydad by tillydad moderator in response to WillowSkye's comment.

    Thanks for the link @WillowSkye . A fascinating project and it will be great to see how this work progresses in the future 😃

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  • tillydad by tillydad moderator

    I have just found and read a new paper that was published this year by researchers from the University of Calgary et al . It discounts the camouflage and social function of stripes . Here is the link for the paper http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145679 .

    This tends to leave the thermo-regulation and anti-fly theories as the best explanations, and these reasons are supported by a paper by researchers at the UCLA . Here is a link: http://news.nationalgeographic.com/news/2015/01/150113-zebras-stripes-evolution-animals-science-africa/

    It is gratifying to know that we were on the right track in our discussion above, although there are still some more studies to be published on the matter 😃

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  • davidbygott by davidbygott moderator

    Another part of the puzzle (by the inimitable Banksy):

    zebra stripes at the laundry

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  • tillydad by tillydad moderator in response to davidbygott's comment.

    Surreal, but fun image !! 😃

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