Does Evolution Explain Tiger Stripes?

[archer75]

yeah, these kind of arguments always make my head hurt.

Yes. I learned some things from this thread -- as much as I could understand from the posts by people who actually know something, but more important for my everyday functioning, I learned about how these arguments go. Of course, I've seen them before, but this one seemed like a very clear demonstration of the main principles. Attack an idea you don't understand on the grounds that your misunderstanding of it doesn't make sense. When your error is explained to you, however politely, attack the explanation and repeat your misunderstanding, then leave.

 

[loveofourlord]

Yes. I learned some things from this thread -- as much as I could understand from the posts by people who actually know something, but more important for my everyday functioning, I learned about how these arguments go. Of course, I've seen them before, but this one seemed like a very clear demonstration of the main principles. Attack an idea you don't understand on the grounds that your misunderstanding of it doesn't make sense. When your error is explained to you, however politely, attack the explanation and repeat your misunderstanding, then leave.

Not to mention most of these people probably think tigers evolved the stripes, as they need to cut down the number of species on the ark and such.

 

[Dale]

Tiger stripes are an example of camouflage. Animals that are well camouflaged survive better than those that are not. This is certainly true for prey animals, like zebras, another examples of stripes. It is also true of predators, like tigers. The stripes make it harder for prey to spot a tiger creeping up on them getting ready to pounce.

I have a photo on my wall of a bobcat. It's a frustrating photo because the head blends in so well with the dried palm fronds behind it that I often can't see the head. It just blends in. That's camouflage. Just as with tigers, the better camouflaged animals had an edge in the struggle for survival.

Why do you think chameleons change color? The same reason, it aids in camouflage. They can camouflage themselves whether they are on wood or on a leaf.

There are insects that look exactly like the wood of the trees they are often found on. Same thing, camouflage makes them less visible to predators.

 

[Daniel Marsh]

◄ Genesis 30:39 ►

New International Version

they mated in front of the branches. And they bore young that were streaked or speckled or spotted.

 

[homohabilis117]

I do expect certain freaks of nature. Wouldn't surprise me to find a blonde woman with a few random black hairs, or a black woman with a few random red hairs. Or whatever. Fine. But striping? Look at a tiger. THOUSANDS of hairs perfectly arranged to form one stripe, then THOUSANDS forming a primary-color section, then THOUSANDS to form the next stripe. This evolved? Really? Evolution appears to be a pretty good artist, then.

Sure you can find scientists providing explanations - but they seem to be telling us what we already know, that's there some chemical or genetic process involved. That's still not telling us WHY it would evolve. If it were just a few random stripes - again - fine. I already attested to freaks of nature. But perfectly striped, OVER EVERY INCH OF ITS BODY? Hard to believe it's not design.

How do evolutionists explain this? They can talk about 'selective advantage' all they want but I doubt it would provide a convincing explanation of how PERFECTLY regular striping 'evolved'.

"Perfect" is a relative term in this example. I'm guessing (and I'm no biologist) that Tiger stripes have something to do with sexual selection. If the present pattern in Tiger striping corresponds to underlying genetic factor (say resistance to disease) females that prefer that particular pattern will have offspring with greater disease resistance. That lineage will continue to produce offspring that continue those characteristics. As to "WHY" this would or would not evolve, perhaps I am misunderstanding you. But if sexual selection is the evolutionary mechanism at play in determining Tiger stripes, those stripes would evolve that correlate to greater survival potential. In other words, those stripes would evolve that benefit the organism in some way, or represent a benefit (like disease resistance).

 

[[serious]]

Now, first off, my studies never dove into big cats, so I can only speak to methods of striping generally. I would suspect that a mechanism like I will explain is responsible, but other solutions may exist.

The OP seems to be asking the WHY while acknowledging that good explanations of the HOW exist. This seems odd as good reasons for the why are much clearer. Coloration patterns are often reinforced through camouflage and/or mate selection (again, examples, other factors could also reinforce these changes). The best answer here seems to be camouflage. As far as the OP, the answer can end there as he doesn't seem to take an issue with the how.

There is also an implied question that does get at the how though. The OP seems to suggest that the hair coloration is controlled by a single gene per hair, requiring one mutation per hair that changes color. This is wrong and gets at a misunderstanding of the how. Now, as I said, I never studied much in the way of big cats, but other animals have stripes too. Insects, for example, often develop stripes through pair rule genes and turing reaction/diffusion models. Now, I was looking for a good approachable graphic to help explain these, but was unable to immediately find anything. I'm thus going off my remembrance of lessons from a decade ago. Mistakes may be present.

Basically, multiple genes are at play that result in kind of standing wave patterns. Let's say you have some gene X that's expressed at the head side, and forms a gradient towards the tail:

XXXXXXXxxxxxxxxx------------

Now, say a second gene, Y, is also produced

XXXXXXXxxxxxxxxx------------
yyyyyyyyyyyyyyyyyyyyyyyyyyyy

Now, here's where it gets interesting. X promotes X and Y, but Y inhibits X. Let's go through a bit slower. Working left to right.

XXXXXXXXXXXXXXXXXXXXXXXXXXXX
yYYYYYYYYYYYYYYYYYYYYYYYYYYY
X promotes Y and X

Xx--------------------------
yYYYYYYYYYYYYYYYYYYYYYYYYYYY
which suppresses X

Xx--------------------------
yYYy------------------------
which leads to Y tapering off

Xx---xxXXXXXXXXXXXXXXXXXXXXX
yYYy------------------------
letting X get expressed again

Xx---xxXXXXXXXXXXXXXXXXXXXXX
yYYy---yyYYYYYYYYYYYYYYYYYYY
Which promotes Y

and so on until you get
Xx---xxXXx---xxXXx---xxXXx---xxX
yYYy---yyYYy---yyYYy---yyYYy---y
Have either of those get linked to genes for hair/skin coloration, and boom, instant stripes.

 

[joshua 1 9]

This evolved? Really?

Actually stripes and spots shows us how DNA combines and then expresses itself. Good design is a product of form and function. Just like Calico Cats come out all different colors. I spent quite a bit of time trying to figure out why a tiger has stripes and why a butterfly has a pattern on the wings.

 

[shakewell]

o