We'll interrupt the more fun pony/super robot crossover discussion for a rehash of pony genetics, the TL;DR and too-much-thought-about version:
The genes related to requisite secondary powers (e.g. temperature resistance for pegasi, earth pony’s prehensile tail, etc) are available in all ponies and not necessarily tribe specific. An unicorn with the gene for temperature resistance, for example, given the right conditions can have higher temperature resistance than the average unicorns, but not to the level of pegasi – pegasi transcribe or translate
* leaning towards differential splicing, but it’s not a very important detail
the same gene into a different variant. Same goes with prehensile tails. The part that is responsible for the tribe specificity is a loci composed of two genes.
The first one, I’ll call it uni1, ear1, or peg1, transcribes a signaling protein – this gene in itself is only transcribed in specific location under specific condition, similar to the genes responsible for limb developments. This signal protein in turn activates other genes that actually encodes the development of limbs – horns, wings, tail, etc
* and my specific fanon, other subtler things like magic receptors
.
The second gene, say uni2, ear2, or peg2, makes sure that, if the embryo somehow have different signal gene only one of them would be active. They methylate
* think of it as putting a protective cap on the gene
the opposing signal gene. uni2 would put a cap on ear1, ear2, peg1, and peg2, and so on. Methylating the other genes ensure that they would not be transcribed by DNA machinery. It’s the reason why there are no hybrids around. At gametogenesis
* generation of sex cells, e.g. semen and egg
all methylations are removed so the embryo doesn’t necessarily have the same active signaling gene as the parents. So how does one of them get dominant in the first place? Flip of a coin, really. Whichever gets to cap the other one first at stem cell level wins
* chemical reaction is actually random in this manner and depends entirely on who bumps into what. It’s just that we observe it on macro-level with excessive amount of molecules, which ups the chance of things bumping and reactions happening
. If for some reason neither or both are capped at this point then the baby may suffer from birth defects or worse miscarriage. It is also possible for slippage to happen and the baby doesn’t have any of these genes on both chromosomes, in which case they will grow being unable to harness the magic inherent in the pony species. Depending on how you perceive the world (e.g. whether this magic is necessary for existence at all) this can be a very, very bad news for the foal.
TL;DR: It’s not strictly Mendelian but yes, other tribes’ gene can be recessive and resurface at random, even when the parents are of the same tribe.
edited 14th Jan '12 6:39:32 PM by Crowind