Posted by:
CKing
at Thu Jun 12 08:29:18 2008 [ Email Message ] [ Show All Posts by CKing ]
>>An interesting study was done in 1995 re avian predators and their reaction to mono,bi or tri colored snakes. The PDF is available through the teriffic Sierra Herps site but has been available through other sources as well.
>>
>>http://www.sierraherps.com/pdf/Eckerman_Mimicry.pdf
>>
>>When we look at corals and milks actively prowling the time is often early AM or late PM when light is fading (or tall grass and forest provide cover) or for the tropical corals, prowling is done late at night (pers experience). The flashy colors do not reveal in low light and these snakes have never been selected by evolutionary/predatory pressure to change from a flashy pattern to cryptic browns or black.>>
L. zonata is active during the day time, but it lives in woodland habitats in general, where its colors blend in surprising well with the woodland floor. The tricolors are only strikingly colored when they are lifted out of their native environments and put in a cage in the lab or when they are crossing a road. When they lie motionless on a woodland floor, they can be quite cryptic. The same is true of a zebra. If you put it inside a cage in a zoo, it is strikingly colored. If you go to a zebra's natural environment, you will realize that it is well camourflaged. In low light, a moving tricolor becomes a unicolor light gray one without any hint of its bold pattern. So, whether moving or at rest, tricolor snakes are actually cryptic, not conspicuous, in their native environment.
>>Exceptions exist though: a black coral snake was found in Orlando years ago and Shannon has a patternless blanchardi from an area know to produce patternless blanchards. I have a patternless gentilis also.>>
An exception to the L. zonata tricolor pattern occurs naturally on South Todos Santos Island. L. z. herrerae is phenotypically more like the common kingsnake than the mountain king that it is. If the tricolor pattern is meant to be conspicuous and meant to frighten predators, then a desert island would be a perfect place to be conspicuous and frightening. Instead, herrerae loses its bright red coloration in an open habitat. Therefore herrerae is a strong argument against the whole idea that the tricolor pattern evolved to frighten predators. Not coincidentally, Gilbert's skink (Eumeces gilberti) has a red tail, and it lives in open grassy habitats. A skink's tail is meant to attract attention, so it is designed by natural selection to have the highest visibility in any given environment. In open grassland habitats, red is highly visible. So, it is no coincidence that E. gilberti has a red tail. Skinks that live in woodland habitats (e.g. Eumeces skiltonianus), however, do not have red tails. They have blue tails instead. Why? Because blue tails are more visible in a woodland habitat then red tails. If the coral snakes and milk snakes want to look conspicuous, they would need to be blue colored in woodland habitats and they would be red on a desert island. Instead we see the exact opposite: they are red in woodland habitats but they lose their red color in open habitats, proving that they evolved to have cryptic coloration. Some of you may jump in and point out that some milk snakes are red and they live in open grassland habitats. Let me point out that the milk snakes found in open habitats are often nocturnal. For example, L. t. campbelli and L. t. celaenops spend most of the day underground and are only active at night. Remember also that at night and in low light red turns to black, so red color can be cryptic even for a nocturnal animal. If you ever drive through a tunnel and you are followed by a red automobile. Just look at the car through the rear view mirror and see it turn black when you go through the tunnel.
>>These exceptions could be remnant genes that re-surface and would prevent the species from being eliminated if the environment were to put pressure on the bi or tri colored patterns. A safeguard gene if you will. Maybe. >>
Or perhaps a black snake can absorb more sunlight directly so it gets warmer quicker. Some of the Sierra Nevada populations of L. zonata are black and white, presumably because it helps them thermoregulate at high elevations.
>>But that line of thought proposes that flashy bands are a recent evolutionary development and these snakes may have been dull brown snakes eons ago and I'm lacking suppotive data aside from a few "safeguard" examples. Colors don't fossilize unfortunately.>>
It is true that fossils do not show colors in life. However, L. triangulum is an old species, and phylogenetic analysis show that the genus Lampropeltis diverged very early into L. zonata, L. pyromelana and L. triangulum, all of which are tricolored. Either they evolved their tricolor pattern independently or their common ancestor was a tricolor. A tricolored common ancestor is most likely. Lampropeltis is in turn descended from a New world ratsnake, quite soon after the ratsnake entered the New World about 25 million years ago, IIRC. L. zonata itself is said to be older than 10 million years according to Rodriguez-Robles. So we are looking at the tricolor pattern having evolved as early as 25 million years ago and persisting for all these years.
>>Nevertheless, we have flashy snakes that apparently warn and startle predators and can also benefit the snake as a hunter/predator.>>
Again, these snakes only look flashy when they are put in a cage in a laboratory. They don't look flashy if you try to find them in their native environment. Anyone who has looked for these snakes in nature would know that they are not easy to find unless you know where to look.
>>Check out Eckerman's paper if you don't already have it wallpapering your snake room.
>>Jeff
Unfortunately, many herpetologists just cannot get over the bright colors of the tricolor snakes and fail to see that they are in fact cryptic in their natural environment. So the myth that the tricolors use their "warning coloration" to frghten potential predators persist even in the scientific literature, in textbooks and in the popular literature. What these scientists ignore is that a predator has to hunt. Unless tricolored kingsnakes are vegetarians, they need to be cryptic to stalk their prey. Having bright flashy colors is simply not a good idea for a predator. We don't see tricolored lions for example, because they would starve to death since their prey would see them before they ever get close enough to make a kill. The same is true of tricolor kingsnakes. They hunt rodents and lizards, animals that have good color vision, so they cannot afford to be flashy and conspicuous to their prey. In sum, flashy colors is maladaptive for a predator like a kingsnake and they only look flashy when they are inside a cage. Further, even warning colorations are not 100% effective. It is better not to be seen than to be harmed or killed by a naive or color blind predator. And that is what L. z. herrerae teaches us. It makes no sense to be conspicuous by being tricolored and diurnal in open terrain.
Finally, what is the evidence that the tricolored pattern frightens predators? There is none. Harry Greene, in his book Snakes, the evolution of mystery in nature, points out that there is not one single observation in nature of a predator, upon seeing the tricolored pattern of a harmless snake, became frightened and not attack it. It shows, if nothing else, that the whole idea of warning coloration is entirely dreamed up by "scientists" who just cannot get over the fact that tricolor kingsnakes look striking in a cage in their laboratory. Well, get over it! Tricolored kingsnakes do not look striking in their natural environment. Kingsnakes are not mimicking anything. They merely evolved their colors because these colors help them hide in plain sight. The tricolored kingsnakes would have evolved their tricolors even if coral snakes never existed.
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RE: Tricolored pattern and mimicry/cryps - CKing, Thu Jun 12 08:29:18 2008
