AdamS Posted October 26 Posted October 26 Can anyone share some information about the genetics of German ram colors? Are certain colors more dominant than others? What happens when you mix different colors? Do certain colors remain recessive? Are there any lethal color combinations? I searched this forum and others, but there isn’t much information available. Perhaps it’s all considered tribal knowledge. I did find the information below from @Fish Folk that answered some of my questions, thank you for posting it! 2
Fish Folk Posted October 26 Posted October 26 (edited) Though it jumps into the middle of a conversation, here is a lengthy quote (not mine) from a 2011 Cichlid forum post here worth studying at length… “Unfortunately, your projections are based on incorrect assumptions. First you have to understand how color is desplayed in the skin of the fish. The color cells are in various layers, and the base yellow color of a Gold Ram would be covered up by the iridescence of the Electric Blue because the iridophores are the top layer of color cells. (An analogy would be the fact that a recessive Gold trait underlies the Red in Swordtails to make them Velvet rather than Brick Red.) Regardless of whether the blue is a dominant, a partial dominant, or even a recessive, phenotypically it will cover or mostly cover any other color modifications. All this is assuming that it is based on a single set of alleles; from what I've seen so far, that is not likely. I have a slight advantage in that I already know how Gold is inherited in Rams. It is actually a partial dominant, but the way in which it displays is quite unusual. A cross between a homozygous normal Ram and a homozygous Gold Ram will produce yellow fry that later develop some of the melanic pigments of a normal Ram. The phenotype is a very yellow, but normally marked, Ram; most hobbyists would not be able to recognize these fish as anything other than normal. To truly display the pure yellow color of a Gold requires that the genes be homozygous. So if you end up with 50/50, it would prove: a) that the EB is also homozygous for gold, b) that the same fish was also heterozygous for the blue, and c) that the blue is a complete dominant. Since I'm about 99% certain that the EB are not carrying a Gold gene underneath (in all the photos I've seen, they still have black spikes), the odds are very slim that you could ever get a 50/50 result. If the EB were heterozygous for gold, then only 25% of the young would be Gold, and 25% would be the yellow/normal color described above. If the EB were a recessive, the Gold would have to be carrying the EB gene - not likely at this point in time - and the EB would still have to be homozygous for Gold. Your second projection is an impossibility by the math, but a possibility by functionality. There is no possible mathematical projection that could lead to 25% blue, as both fish would have to be heterozygous for the blue, and the blue would have to be a recessive - impossible because the EB is displaying the color! However, the fact that those fry may be weaker could result in fry losses heavier in that portion of the spawn, resulting in a skewed ratio. The same thing happens with spawns involving heterozygous normal and albino fish; albino fry are weak, and have a higher rate of mortality than the normal fish, resulting in a different ratio than the math would indicate. Your last projection is actually what is likely to happen. I'm reasonably certain that the EB Rams are homozygous for that color, if the trait is controlled by a single pair of genes. If EB is a complete dominant (I seriously doubt that it is), all the young are going to be EB. If it is a partial dominant, a heterozygous individual will have a partial dominance display, resulting in heavy blue iridescence without the complete coverage of a homozygous individual; I suspect this is the case, as I've already seen some individuals that most seem to think are just "poor quality" EB Rams. If the gene is a recessive, there will be no EB coloration on any fry. The Gold I've already explained above, so your genotype is likely to be BbGg, with the lower case letters representing the normal color genes in each pair of alleles. What the phenotype would look like is anyone's guess. Genetics is 50% math, 50% biology. You can calculate what the probabilities should be, but the biology will always throw a few monkey wrenches into the mix. If I could get some EB Rams, I'd be doing this cross myself through a couple of generations to see how a Gold base might alter the EB coloration (remember the effect on Red Swords). Edited October 26 by Fish Folk 1 1
AdamS Posted October 28 Author Posted October 28 This is amazing information, thank you! I was hoping it was more clearcut but this makes sense.
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