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    Phenotype names

    This thread was triggered by a discussion in the thread http://www.theangelfishsociety.org/f...Ghost-genetics but since that thread had already gone way off topic, and this was even further removed from the original, I thought it best to start a new thread.....

    The name phenotype was originally coined by Gregor Mendel, the father of genetics. Mendel didn't actually use the name "genes", he talked about "factors", the name gene was first used in 1909 by Wilhelm L. Johannsen, (I know because I just googled it).

    As most people reading this are probably aware, "Phenotype", as defined by Mendel means the appearance of the organism being studied, whilst "Genotype" is the genetics of the organism. Mendel worked with pea and bean plants studying characteristics such as height and flower colour, so he was using the term very much in association with one or two clearly defined characteristics.

    With angelfish 17 different gene mutations at 13 distinct loci have been identified, that is if you include "Naja" & "Hong Kong" gold which are both now believed extinct, "Notched" which is a deformity rather than a desirable trait, and "Bulgarian Green" which is clearly a new mutation, but hasn't yet been accepted by TAS. In short, when we talk about "Phenotype" we're often talking about appearance resulting from the interaction of many different gene mutations at multiple different loci.

    Part of the conversation in the previous thread related to the appropriateness of using the term "Marble" as part of the phenotype name for a fish with a gold marble gene, but very little in the way of black markings. Thinking about that conversation, it occurred to me that our phenotype names are based, at least in part, on genotype rather than appearance. There is always variation in appearance between fish with the same known genotype, whilst the phenotype names applied to those fish tend to be based on the appearance of a "typical" fish with that genetic make up.

    As an example, "Koi" is the phenotypical name applied to a blushing gold marble (either homozygous for gold marble or heterozygous in combination with a gold gene). As we know, koi can be bred for specific traits, most noticeably very little black coverage, or lots of black. Similarly whilst the typical "koi angel" when the name was first used in the 1980's was a black and white fish with a gold crown, careful line breeding has produced fish that are almost red, with practically no white, and conversely black & white fish with little or no red, orange or yellow colour. These latter fish are sometimes called "panda koi" whilst terms like "High Coverage" & "HR koi" are often applied to those fish with a deep orange/red colouration.

    This set me wondering about when it's appropriate to use a different name for the phenotype of a particular fish. For example, gold marble angelfish vary immensely in the the amount of black they express. On occasions I've seen fish that are genetically gold marble, which physically have no black at all, should that be called a "gold" or a "gold marble"? Gold marble could lead to confusion, whist gold could lead to annoyance if the purchaser was after a fish for a breeding project, and wasn't seeking a genetic gold marble.

    Going back to koi, If I was deliberately breeding a line of "Panda koi", and I had them to the point that a randomly selected pair would produce all, or at least a high percentage of, panda koi offspring; then I would feel justified in using the distinct phenotype name "panda koi" for them. But on the other hand, if I had a pair of "normal" looking koi that produced a mixture of, say, 10% pandas, 80% "normals" & 10% high coverage koi, I personally would feel uneasy about applying a distinct phenotype name to either the "pandas" or the "high coverage" fish, although I might consider describing the best coloured individuals as "selected" and charging a premium for them, on the basis that they were more desirable.

    In my view, the use of a distinct phenotype name, implies that there is something both distinctive and consistently reproducible in the fish to which that name is applied.
    A year or so ago a German supplier was offering "Mosquito Copper" angels on their lists, the price was high, and those who ordered them found themselves with something which looked identical to a gold blushing aka sunset angel. As they grew, these fish did tend to develop some red spotting on the body, supposedly these red spots resembled mosquito bites, hence the name. Clearly the breeder had put in some effort to develop this variety, but in choosing to name them something other than sunset or gold blushing, they achieved a premium on the sales of their fish, but only at the expense of upsetting the purchasers & killing the market (it's noticeable that none of the suppliers who carried these fish a year or so ago, list them now.) Had the breeder described them as mosquito sunsets, or red spotted sunsets; then the purchasers would more likely have been happy with their purchases.

    With dogs, there are recognised "breeds", these breeds, are the result of the combination of multiple mutations to produce the one breed and that breed is then continued by only breeding to other animals of the same breed. you can't produce a Labrador by crossing a German Shepherd with a Poodle, for example.

    With angels, although we have three recognised species, mostly we're concerned, not with "breeds", but with colour varieties of one of those species, Pterophyllum scalare, some of those varieties will breed true, others will produce only a small percentage of the variety when bred together.
    We also have populations, fish from a specific locality which are clearly distinctive when compared to other angel populations, for example Rio Nanay, Manacapuru, but which are all technically "silver" angels.
    Finally we have strains, or lines, for example "Dantums" which are allegedly a cross between altums & scalare, but in my opinion are probably derived from a cross between a domestic scalare and a rio Nanay, which are also scalare, despite sometimes being known as "Peru altum".
    Clearly the breeder of "Dantums" has put a lot of effort into producing a fish that's very distinctive in appearance compared to a typical domestic silver or albino, but do they warrant a distinctive name? If I breed my rio Nanays to my domestic silvers, and end up producing a similar looking fish, should I call them "Dantums" which would imply that they are related to the original "Dantums", or should I give them a distinctive name of their own? which could lead to confusion & disappointment in the purchasers who end up with something that looks just like a Dantum?

    I know this is a long & meandering post, but I'm interested in other people's thoughts on when it is, or isn't, appropriate to apply a varietal/phenotype name.
    Last edited by Pterophyllum; 10-18-2015 at 05:55 AM.
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