Reptile & Amphibian Forums

Over on the milksnake forum I have initiated the contreversial topic of a "dual-gene theory" to explain the EXTREME hondurans. I will repost it here in regard to trying to find out how you would REMOVE a single gene from a possible dual gene line if you could not identify the dual gene animal by sight alone. Thanks

OK, been taking a bunch of flak for a while now with no ill will and nothing gained. Time has passed and breeding trials with EXTREME lines are commencing so I will put forward a theory available for scutiny(NO CRACK JOKES,lol)and for those with such animals...Here goes nothin....
IF we can assume for a minute there are 3 phenotypes(EXTREME,HYPO,and EXTREME HYPO)and we know that the EXTREME line came from the HYPO line 66% of any EXTREMES will be het HYPO. Now how do we eliminate the HYPO gene from the EXTREME line? I would suggest test breeding to normal het hypos. If the EXTREME is het HYPO(66%)then 50% of the resulting offspring should be HYPO,50% normal het HYPO==all het EXTREME. IF the EXTREME is in fact a EXTREME HYPO then ALL of the offspring will be HYPO het EXTREME.
Now by another generation there will be some strange breeding trials like the one posted below. IF we assume his male is EXTREME het HYPO, and within a generation we find where a male EXTREME(poss het HYPO) was bred to "known" het EXTREME(poss het HYPO)and ALL morphs were EXTREME and none were HYPO then at least 1 of the parents was NOT het HYPO.Resulting offspring would still be 33% hets though.....
I dont have time to finish this here now, but could use the HELP if someone sees the finish line here. Bottom line, it will be MUCH harder to PROVE the "dual-gene theory" than it is to PROVE a HYBINO. It is much harder to remove a gene than it is to put one in,lol. Man I know I should have stuck with the science thing but sales just pays better, ouch my head.

if you were able to separate the extreme gene from the hypo gene, what phenotypic characteristics would you look for, so that you would know you're "done"?

daveb

You breed a KNOWN HOMO or HET for HYPO to the EXTREME(0% het) and you get only hets/dbl het offspring.Of course this is assuming the 0% was repeated....

I checked out the milk forum too, and the bottom line is that some genes (many genes) are not explainable using mendelian genetics alone. In fact many genes are not explainable through breeding trials period. Unless you understand the molecular mechanism it will just seem random.

While this is frustrating to breeders, especially since some folks who can make a punnet square think that they know all there is to know about inheritance, it is the truth. Genes have many weird mechanisms for changing phenotype, and new ones are found all the time. In fact reptiles are probably the least studied group of all animals when it comes to genetics. We know lots about viruses, bacteria, mice, rats, humans, and african clawed frogs...but almost zilch about reptiles and birds.

It sounds to me like you are making a lot of assumptions about this trait. Where did the whole 66% of all hypos being het extreme come from? Why 66%?

My arguement was that if a like gene popped up alongside an existing one that it would be masked. The fact that they would occur within the HYPO line to begin with we have to expect a ratio high HYPO. If you bred a EXTREME HYPO with a EXTREME het HYPO you would get 50/50(figuring you could tell the difference but likely not..).A HYPO het EXTREME x HYPO het EXTREME would give you 75% HYPO(66%het) and 25% EXTREME HYPO.I dont know how many are being produced from hets, but I think its safe to say that there are alot of double morphs out there if I am right.
That said, I figured out how to determine if it is a single gene or a double gene. Take the "most EXTREME" specimen you can find and breed it to a het for nothing to produce hets(f2).When you cross these f2s back to each other you would expect 25% to be morphs if a single gene, but 75% should be morphs if its a double gene....but thats in the f3 generation. But it makes sense to me,lol. Jeff

one thing jeff, if you bred the best extreme to a normal to make hets those hets would be F1's NOT F2's. breed the F1's together and 50% of the F2's should be extremes if its a simple recessive. i could be wrong but i beleive it has been prooven the extreme is NOT a double homozygot if it is then the above F2 clutch would vary 25%,25%,25%,25%, but even then its not that predictable with hets. i have dbl.het.(anery&albino) hondurans first year they bred half the clutch were anery second half normal poss.dble.hets, next year same thing, 3rd year 1 albino,1 snow rest of clutch poss.dbl.hets no anerys, 4th year got 1 snow 2 albinos no anerys, last year i got anerys no albinos no snow, this year who knows??? it does vary alot,,,,,,,,thomas
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Morphs... just like baseball cards BUT ALIVE, how cool is that???

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I say f1 is the parents that already HAVE the genes in them, f2 is the "dble hets",and f3 should be 25/25/25/25. Of all these added up, 75% should be morphs if dbl hets, 25% if single het. It is very important to try this with THE BEST, most likely DOUBLE morph extreme to begin with or you will only get 50% morphs...and will muddy up the experiment. I think 3x the number of morphs would be obvious enough to discount variability but you may need more than one clutch--admittedly. Jeff