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Posted by terryp on January 13, 2003 at 11:56:14:
with all the threads on black rat snakes over the last week you would think someone would step forward with a discussion on melanism. lol It may be that nobody wants to discuss it, but I'll throw an attempt out and if you want to correct/add/delete, etc; that would be great. I went back to an article in Reptiles Magazine published November, 2000. There is an article written by Glenn Fanhauser (lives right here in Bakersfield where I do so I might be byassed. lol). It's titled: "MUTANTS! A guide to snake variants and the genetics behind them". He covered melanism and I'll give you a quote out of the artcle:
"Melanism is much more common in wild populations than amelanism because melanism does not necessarily confer evolutionary unfitness as much as amelanism often does. (Albino animals are usually more vulnerable to predators than melanistic animals because they are not able to camouflage themselves as well.) Because of this, there are several wild populations of reptiles that are naturally melanistic in parts of their range. Some examples of these populations are beaded lizards, southern Baja populations of California Kingsnakes, black rat snakes, black milk snakes, Mexican black kingsnakes, variable kingsnakes, gray-banded kingsnakes, and coachwhips.
Generally melanism is a condition that develops with age, intensifying as the animal grows. Therefore, an individual from an all black species would most likely be dark from birth, while melanistic populations would darken later in life, such as in black rat snakes and black milks.
However, this is not always true. There are some black species that are not melanistic at birth, and there are some melanistic populations that are black at birth. At any rate, it would still be correct to call a species of all-black snakes melanistic. Melanism is controlled by a simple recessive mutation in some animals , but is also controlled by multiple loci in others"
I realize that's out of context and there's more discussions on other morphs in the article, but that was Glenn's discussion on melanism. I didn't post this because I think it is correct or incorrect. I posted it because I think it's relevent to the thread discussions lately. It seems almost like Kentucky has both worlds with their black rat snakes. They have black rat snakes that are black at birth and don't darken so to speak and they have black rat snakes that are lighter at birth and will darken with age.
