Another explanation claims that the stripes help the zebra to regulate its body temperature, another explanation is that the individuals in the herd recognize each other when each individual has a slightly different pattern of stripes, but from my experience, which is now being confirmed by a new study, the reason is the sensitivity to flies
In nature trips in general and in Africa in particular, questions often arise about the advantage (or disadvantage) that a color model gives to animals: colorful butterflies, gray elephants and rhinos, tigers carrying bundles and so on and so forth.
The answers to the question of the advantage are different and varied according to the species, the size and the position in the food chain: the male peacocks decorate themselves with colorful tails to attract females, black beetles to store heat, lions that color like the color of dry grass and other color models and their reasons.
One of the most prominent models, and therefore also problematic for understanding the advantage, is the striped model of the zebra.
One of the accepted explanations for many of the color patterns is camouflage, and indeed when a herd of zebras moves between trees, a play of light and shadow is created that the stripes of the zebras blend into and perhaps confuse a possible predator, but the zebras spend most of their time in open pastures. Those in favor of camouflage explain that in the movement of the herd, the stripe pattern creates confusion that makes it difficult for a predator to concentrate and follow a single individual.
Another explanation claims that the stripes help the zebra to regulate its body temperature, another explanation is that the individuals in the herd recognize each other when each individual has a slightly different pattern of stripes.
For those who have spent more time in the field and are well acquainted with the conditions in the areas where the zebras graze, the accepted explanation has developed for a long time that the striped pattern "confuses" the stinging insects and especially the tsetse flies. This explanation is supported, among other things, by the fact that the black zebra embryos develop the white stripes only in the phase before calving as protection from fly bites.
Until today it was an interesting explanation but without reference, now a study by researchers from Sweden and Hungary is published in the Journal of Experimental Biology http://jeb.biologists.org/content/215/5/iii which establishes the popular assumption and gives it a scientific basis. According to the researchers "the stripe pattern makes the zebra unattractive to flies", where the key to repulsion is the way the stripe pattern reflects light.
To substantiate the "protection from flies" assumption, their various reactions to the light of horseflies were examined. Tabanids is a series of stinging flies that have a worldwide distribution, their sting is painful and disturbing and they carry diseases and parasites.
The researchers began by testing the reactions of flies to black, brown and white horses and found that in black and brown horses the light is polarized evenly on the surface so that the light is reflected from it, making the dark horses very attractive to flies, since the light is reflected from the horses in waves that reach the eyes of the hungry flies on a balanced plane like a snake crawling on the ground the flat
Later, the form of light reflection from white horses was tested and it became clear that white horses reflect unpolarized light whose waves travel in many different planes. This fact creates a low attraction and therefore white horses are less disturbed than their dark brothers.
After the team of researchers realized that the flies are more attracted to dark horses, they moved on to check what light is reflected from the zebra stripes and how would this affect the flies? To find out, the researchers produced panels of different sizes and painted in different patterns. Striped panels were the more zebra-like model. The boards were scattered in horse farms and counted how many flies reached each model, it turned out that the boards that attracted the least flies were the ones with a striped model.
The fact that the flies were attracted to the striped pattern less than the white ones came as a surprise to the researchers, since the striped pattern still has black stripes that reflect balanced focused light. And again it turned out that the narrower the stripes were and the more similar they were to the zebra pattern, the less attractive they were to flies.
Later, the researchers continued and placed four horse models in life size and colors: brown, black, white and a striped zebra model, the models were sticky to capture the flies that would come, and again it turned out that the zebra model captured fewer flies than all of them. It also turned out that the narrower the stripes were, the fewer flies were attracted to the model.
The researchers' conclusion is that the zebra has developed a pattern of stripes in which the stripes are narrow enough to ensure the minimization of the flies' attraction to them. The highest selective pressure for the development of the striped pattern arose as an adaptation or as an adaptation to the bites of the flies in Africa."
To this I will add that there is probably a compromise between the need for a dark color that prevents radiation damage and the pressure to develop protective measures against fly bites, meaning that the zebra pajamas are a protection against both radiation and fly bites.
is that so? If so, why isn't the striped model common among other Persians who suffer from flies?
to the notice of the researchers
More on the subject on the science website
- A duel between two proteins helps to create patterns such as zebra stripes
- There are mammals in the wild that are able to choose the sex of the newborn
17 תגובות
It's worth deleting the comments here..
Go
Why stop at Zebra?
You can ask why the panda looks with these spots... etc. etc.
inconclusive..
Asaf:
The question you ask can be asked about any trait that evolved somewhere during evolution.
After all, the feature was useful, so how did it happen that it didn't work at all?
The reasons for the interest are many and varied, among them the probability of a mutation that will lead to the discussed result and the reproductive separation of groups for some reason (geological, psychological or genetic).
I am not aware of a selective pressure leaf that activates solar radiation in favor of dark fur.
Dark skin - yes, but hair? Why?
point:
Check if there are no flies among your relatives.
Grace:
You should read the book Endless Forms Most Beautiful
There are answers to your question there.
http://www.amazon.com/Endless-Forms-Most-Beautiful-Science/dp/0393327795/ref=sr_1_1?s=books&ie=UTF8&qid=1331413735&sr=1-1
Adam Red:
The offspring of all the animals recognize their verifications even though they do not have stripes on their rumps.
There are all kinds of properties that can be used and the animals do use them.
It is clear that if my saddle has stripes on the back then the offspring will also use them, but contrary to the current explanation - no research has been done that shows any advantage by improving identification through stripes.
It is not difficult to conduct such research.
You can group a lot of horses, some of them miss the hindquarters, and see if the size of the group of foals that lose their mothers will decrease in the striped ones.
My intuitive feeling is that this will not happen, partly because it is difficult to reduce the number zero without reaching negative numbers.
In the present study, they experimentally showed that stripes have a measurable effect on the attraction of flies.
By the way, if I may guess, the enforcement is an important component in the answer to the question of Asaf (Here! There is another animal that has developed a pattern of stripes!).
More than that: the saddle even further confirms the explanation because the stripes developed precisely in the area where the flies are more strongly attracted and therefore it probably happened for the same reason.
To all the honorable believers:
Evolution is a proven scientific fact (at least repeatedly confirmed).
If there is an opinion or other belief that has no evidence at all, it is probably (and I say this gently) that it is the problem, not evolution.
Even so, I agree that believing Jews, who find ways to reconcile their faith with scientific truth, do a little more wisely than those who don't,
From Wikipedia: "Laukfi has a dark brown body with a velvety texture, a light head and white-striped hind limbs. Due to the stripes on its back, the okapi resembles a zebra from afar. The explanation is that the stripes are used by the cubs to identify the mother in the dense rain forest and track her, as well as for camouflage."
As you can see there are different explanations for why a mammal is striped and why its color is uniform. The above explanation about the zebra is another theory. Interesting, indeed, unique, but not more than an explanation.
For Okafi's picture:
http://upload.wikimedia.org/wikipedia/commons/1/18/Okapi2.jpg
I find the explanation given here rather problematic. Like other comments here, even if being stung by fewer flies ensures healthier species, it is hard to see that what resulted in the prevalence of the patterned skin. Mustn't it be that the species stung by more flies, on the long run, develop a stronger "resistance" to become sick (like other animals in the wild)? And if the pattern developed during the previous centuries mustn't there be an early species with some other pattern that was not very effective in scaring off flies, and then it got refined gradually?
Arnon, as a religious person I can tell you that you are wrong. Judaism does not believe that the Creator of the world created us to look at nature, to say "What a beauty! Thank God!" Nothing more. The Creator of the world created us so that we would learn and explore nature and open up the world. Even a 3-year-old child can admire the beauty of a zebra, we have a mind to understand why this is so.
If we followed your approach we would not have discovered any of the laws of physics that preceded the world, there would be no engines, no computers, and no modern product that you see around you.
In short: it is complete nonsense to say that Judaism opposes the scientific method.
Even regarding evolution, many of the believing Jews do not think that it contradicts their faith. See the entry "Judaism's relation to the theory of evolution" in Wikipedia.
"The zebra has stripes because the Creator of the world got involved. He wanted us to understand that there is planning behind creation." - End of discussion.
The zebra has stripes because the creator of the world will get involved. He wanted us to understand that behind creation there is planning and not just patterns that repeat themselves.
Believe in the creator of the world and praise him and keep his commandments and reject the "hebel-lucia" theory of the son of the monkeys Darwin!
Actually, if you think about it, the cows have developed a similar "mechanism".
I wonder if the black spots also reduce the size of the various flies or insects.
What is amazing about zebras is the way the stripes are arranged, I wonder how such a precise separation between the colors is created, and how it is uniform along and across.
In short, has anyone studied the evolution of zebras?
Why don't cows wear stripes?
Because they wear spots.
still skeptical,
Your question raises a very interesting point - who exactly does natural selection work on? From the question comes the implicit assumption that natural selection works at the level of the species, that is, the bites may lead to its extinction. In practice, the accepted explanation today is that evolution works at the level of the individual, or rather the gene. That is, Zebra A, which is more resistant to flies, will be healthier and free of parasites and then it will pass these genes on to the next generation.
to the people,
1. You know, if they say that everything is affected by everything and everything depends on everything... then they are actually saying nothing!! More specifically, the biologists first try to map the factors influencing each phenomenon (in this case, the different possible causes of the stripes) and then they try to "arrange" the pieces of the puzzle in their place - who is more important and when.
2. Talk of "desire" and "aspiration" in evolution is merely professional jargon that hides the intrinsic tendency of the system to reach certain states (that is, the selection of the most adapted). No real external desire is meant.
I have no idea... maybe because the flies can transmit diseases and parasites...
How exactly does protection against flies provide better survival?
Are there zebras that have died from fly bites?
Why should the assumption be that this or that reason or another? Why can't it be both, a set of factors that manifest themselves to a greater or lesser extent.
And another small note - from the writing a picture is drawn as if the development was due to the desire of the ancestors of the zebras for protection against flies.
As I understand evolution (and my understanding is undoubtedly limited) the direction is the other way around, i.e. there was an initial mutation that gave some kind of advantage (say against the flies, or less chance of being predated or both) and as a result the zebras with the mutation survived longer and so on, that is, there was no " Desire" in protection against flies, simply protection against flies provided some kind of superior survivability...
I don't know why, but when I see the black and white stripes in the skin of a zebra, I don't really feel like eating that thing. It conveys inedibility. Like the bands of radioactive radiation. It conveys something not good.
Maybe in the past it worked for them and that's why they are like this today.