As I understand it and I could be wrong. Albino is from Latin and means “white” so has been used for Albino humans, etc. It’s usually applied to most animals that lacking melanin would be white but doesn’t really take into account multiple different pigments and the genetics involved, it’s just a white animal or human. Amelanism is a way more precise term denoting the exact pigment that is turned off. Technically, there are a ton of, say corn snake morphs, for example, that would all qualify for the term Albino but there are many different genes involved, which is why it’s not a term generally used nowadays.
While I will follow the generally used terms in different species, I do appreciate the corn snake market where a bigger push is made to be precise than some other species.
Sorry to be a bit late to the party, I do not tend to jump on here on the weekends.
@elementalexotics hit the nail on the head though. Albino/Amel are just to different ways to say the same thing. Historically Albino was used to describe the red-eyed/white phenotype that was most commonly known from mammals which only have melanin. As time (and science) progressed it became obvious that some animals have more pigments than just melanin and when you take melanin out of those animals they still have some kind of colour left over.
Depending on just how anal-retentive of a person you are dealing with, some people will insist that animals that are phenotypically red-eyed/white are “Albino” while animals that are phenotypically red-eyed/white+red or +yellow are “Amel” even though the basis of the morph is the exact same gene.
So it is as I was thinking. Same genes, just different terms. I will probably stick to using albino since more people know the term, and it is the one I started out using. Thanks for confirming what @elementalexotics said (and thank you elemental for chiming in too).
Amel is designated by the exact pigment that is turned off, specifically Tyrosinase.
Let’s take Burmese Pythons. There’s Albino and Caramel. Albino in Burmese is Tyrosinase negative, which makes it technically Amel but it’s still a type of albinism. Caramel is Tyrosinase positive. It’s still a type of albinism.
In Retics, the most common Albino (purple, lavender, white, Mochino, etc) that reside on the same loci are Tyrosinase positive albinism.
Amel in Retics (and the other genes compatible on that loci) is Tyrosinase negative which is why Amels have red pupils versus a lavender which has black because there’s still the melanin producing enzyme Tyrosinase. Keep in mind, breeders name animals genes without genetically testing them. Amel in Retics isn’t named because of the color of the animal but because the original Amel was named Amelia. Any breeder can name a new morph whatever they want, even if it’s not ‘genetically’ true.
I’ve attached a side by side comparison of a Tyrosinase positive Lavender Albino Retic and a Tyrosinase negative Amel Albino Retic.
Yep, same kind of situation. We see it in some boa, retic and burm morphs as well
Amel is shorthand for amelanistic. a- is a prefix of negation from the Greek usage a- or an- for “not” and melanistic is a derivative on melanin that comes from the Greek term melanos, meaning “dark,” Thus, literally translated as “not dark”, or, more properly, not carrying the dark pigment melanin.
Tyrosinase is not a pigment, it is an enzyme that processes tyrosine. The processing of tyrosine is a necessary critical step in the production of melanin. When tyrosinase is absent, this critical step cannot occur and so the pigment is not produced.
Or they named her “Amelia” because it played of the already existing and long-established use of “Amel” being used in the hobby and the story was corrupted with time…
As I noted above:
How long is a piece of string?
There is no cut or dry answer to that.
In terms of genetics, there is only one type of albinism; Tyrosinase-negative (T-neg) amelanism. Anything that is not T-neg is more properly classified as hypomelanism (the “hypo-” prefix deriving from the Greek for under/below) because they are producing melanin, it is just displayed at less than (read: below) normal levels.
In the absence of genotype, anything that gives the phenotype of red-eye, white (or red-eye, white/yellow, red-eye, white/orange, red-eye, white/red in organisms that have pigments in addition to melanin) is typically considered albinism. This is why there are multiple “albinos” in boas and Burms and retics and humans. Logically, we know that only one of them can be the actual real Albino, but unless/until a genetic level interrogation is done, we are left with nothing but guesswork
I appreciate the response and enjoy chatting genetics.
To my understanding, and the understanding of the history of Amel Retic history, Amelia was named as such not because of her color. She was also named as such prior to proving out the gene as hereditary.
Where we disagree is about how many types of Albinism there is. While I do agree that Amel/T negative is the most traditional form of Albinism and the one we immediately think about when we hear that word: picturing a red eyed animal with white/yellow skin. Recent studies show that in humans alone there are 7 types of Albinism, both T + and T -. The enzyme is defective so it does help create some melanin but it’s incomplete, thus creating a type of Albinism-one could say it’s incomplete Albinism. I think that the same can be said for animals (with various number of Albinism in different species)
I am very interested in this conversation and do appreciate the responses.
Per my previous post (slightly edited and emphasis added)
The conventions of old change as the science progresses and provides illumination in the dark corners into which we previously could not see. Yes, in the pre-genetic era, anyone with white skin and red eyes was considered an albino. That said, it was also recognized that some albinos were different than others because they were not genetically compatible. But with the advent of the genetic era and the microscopy era, it was discovered that only one of these albino types was the true tyrosinase-negative, amelanistic Albino. All the others, regardless of appearance, were neither amelanistic nor tyrosinase-negative. Thus, by every biological definition, they are hypomelanistic and not albinistic. However, getting the entire human population, many of whom at the time were scientifically illiterate (not too different from today actually…), to understand that difference was a bit too much inertia to change and so the epithet of albino remains for any red-eyed/white human.
We see this within the hobby as well. It has been incontrovertibly proven through both genetic and molecular studies that the Amel morph in corns is not to the tyr locus and that they produce melanin. And yet we still call them Amelanistic corns, despite the evidence to the contrary. Because of inertia.
At the end of the day the fact remains that there is only one way to be amelanistic and that is to be tyrosinase-negative.
Think of it like percentages. There is only one 0% but there are an infinite number of ways to not be. 0.00000000001% melanin is still not 0% melanin, even if they look the same