Reptile & Amphibian Forums

My goal is to produce some dark phase split banded Mexmex.
I have a dark phase female and an exceptional splitbanded male that I am breeding this year for the first time.
In this pairing would the traits be co dominant and the offspring hatch out double homozygous (dark ground color and splitbands)or will I have normal looking offspring carrying these traits (double heterozygous)??
If one trait is dominant (let's say the splitbands) will they be heterozygous (het) for dark phase and vice versa??
I know of no one trying to produce these, but I have seen some being produced from dark phase to dark phase pairings. Are these two traits just anomalies or are they genetic??
Any help would be appreciated greatly.
-John Lassiter-

Here is a pic of the pair.....

John,

Many genetic traits are much more complex than simple Mendelian dominant/recessive traits. For that reason, you can't necessarily predict the outcome of matings using the same simple principles.

I suspect that the darkness of the background is probably a polygenic trait involving several genes at once. Some individuals are darker than others, but there aren't only dark or light individuals. There is a continuum from the lightest to the darkest snakes. Compare this to height in people. Humans don't just come in "tall" and "short". They come in a continuum of heights. You can't be heterozygous for tall, just as I suspect a snake can't be het for dark.

Of course, you could be right that it is a simple one gene trait, but it doesn't seem as likely. If it is, even then you have to figure out if darkness is dominant or recessive.

If one trait is dominant (let's say the splitbands) will they be heterozygous (het) for dark phase and vice versa??

Again, assuming both traits are single gene traits (see above), and assuming splitbands is dominant over normal and dark is recessive to light, THEN if you crossed them together you would get all splitband offspring that would be het for dark.

I know of no one trying to produce these, but I have seen some being produced from dark phase to dark phase pairings.

Even if it isn't a case of single gene inheritance, you would expect a pairing of two dark phase snakes to produce more dark snakes, just as two tall people tend to have taller children.

Are these two traits just anomalies or are they genetic?

This is a common misconception in the hobby. People assume traits are either single gene dominant/recessive traits or they aren't genetic. MOST traits that are heritable (i.e. genetic) are not inherited in as simple dominant/recessive or codominant ways because they are governed by multiple genes. Therefore most traits are harder to predict than by simple mathematical methods.

This is why it took so long to figure out how it worked. People knew about inheritance for millenia, but it took until 1866 for someone (Mendel) to "crack the code" by ignoring complex traits and only focusing on the simple ones that he understood.

Chris
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Chris Harrison

So Chris,
I should treat the genes in this pairing like I would my Striped calkings and banded calkings. Or like my Thayeri and Alterna?
I thought it would not be as simple as I stated. That is why I asked.
I hate it when I see people selling milksnake phase thayeri that are het for leonis and vice versa.
I have bred dark alterna to light alterna in the past and have had variations within the offspring. I take it this pairing will yeild the same type of variation.
That is great. I love variation within a clutch. I see some more sleepless nights ahead when these eggs are hatching.
Thanks Chris.......I had a feeling it wasn't as simple as an Amel, hypo or axanthic gene.
-John Lassiter-

>>So Chris,
>>I should treat the genes in this pairing like I would my Striped calkings and banded calkings. Or like my Thayeri and Alterna?
>>I thought it would not be as simple as I stated. That is why I asked.
>>I hate it when I see people selling milksnake phase thayeri that are het for leonis and vice versa.
>>I have bred dark alterna to light alterna in the past and have had variations within the offspring. I take it this pairing will yeild the same type of variation.
>>That is great. I love variation within a clutch. I see some more sleepless nights ahead when these eggs are hatching.
>>Thanks Chris.......I had a feeling it wasn't as simple as an Amel, hypo or axanthic gene.
>>-John Lassiter-

John, I'm going to attach a couple pics to help make my point. These two ratsnakes are from southern Texas. One is from a population which has a heavy tendency towards what we call "reverse-stripe". The blotches are split down the middle of the back....

These are the ones from near Hebbronville and Freer. The other snake is from the Brazos Island pop.

They are both of the subspecies, Pantherophis guttatus meahllmorum. The B.I. rat has some tendencies for split blotches also, but not to the extent of the previous pop. ASAMOF, these tendencies can pop up almost anywhere in the range of meahllmorum.

The point is that it doesn't act like a simple recessive trait, although they are sometimes sold as if they were. In reality you can get all different stages of "stripedness" in the same clutch. If you put two very striped individuals together, the babies will turn out mostly very striped, I believe.

The same thing is true with color in this and other species. Some babies can turn out light and some dark. You can breed them for a trait by putting together snakes that are very dark or very light depending on what you want, and eventually you will get some tendencies to show up. I believe this is happening all the time. I experiment myself along those lines with some species.

Sometimes I think we try too hard to make certain traits breed true. I had a strain of Elaphe dione from China that bred some very light colored individuals, but eventually the strain lost its distinctive pattern and hardiness, breeding weak and high strung young. They were pretty, but made lousy pets.

Your two snakes are both beautiful in their own right. I probably would pair them too. But I suspect that you won't get some of one and some of the other, but mostly color/patterns inbetween the two. But that could be very nice. And none will be het, of course, imho. If you wanted light and split-banded, I think you will have to pair two that are alike that way. Again just my opinion.

Also, I don't think they would be like the thayeri. Thayeri produces milksnake and leonis phases and some inbetween, and those are "morphs" that pop up, not so much the inbetween stuff. My leopard rats, Zamenis situla, are like that. The babies are either striped or blotched. Those are morphs. Same as in the Cali kings. Your snakes are not morphs, imo. I would call them color and pattern phases.

Hope it helps a little and best of luck with those.

PS: Saw a pic of your w/c Mex. milk recently. Very nice. Are you going to breed those?

TC

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Ratsnake Haven: Calico and hypo Chinese beauty snakes, Mandarin ratsnakes, Chinese twin-spotted ratsnakes, South Korean Dione's ratsnake, leopard snakes, Great Plains ratsnakes, and corn snakes

Terry,
I have bred everything you referred to except for the actual Brazos Island population of Southern Plains Ratsnake.
I know that my Mexmex are not like Thayeri when they hatch. I just think they are variable when they hatch. I believe the Mexmex pairing WILL yeild a variable clutch much like a dark to light alterna.
ALso Thayeri offspring that are Milksnake and Leonis are phases or patterns and not "morphs". There are no morphs in thayeri.
I think amel, anery, axanthic, hypo and lavender are morphs not patterns like milksnake and leonis.
I appreciate your help too Terry. With all the Thayeri, Mexmex, Brooksi, Californiae and Meallmorum breedings this summer I am sure to miss out on some sleep when they are hatching.

I am looking for a male Jim Wells Co.,TX Mexican milk to pair with the female I collected on Jan. 1 of this year. She is not to adult size, but will be next year.

Thanks for your help Terry,
John Lassiter

John, I know that the mutations are called morphs in the hobby, but I thought there were pattern morphs too. For instance, thayeri breeds true to certain patterns, like leonis and milksnake.

I guess you're right. The hobby calls these things "phases". Sometimes I forget and use a broader scientific definition of the terms. I often think of a snake, like the Southern Plains Ratsnake, as a morph rather than a subspecies. The Miami phase corn has gotten me mixed up, because it's just a color/pattern phase in the hobby, and to me my Miamis are locality morphs.

Oh, well. Guess I'll have to learn the lingo better in the long run.

I love the last pic. That's my favorite mexmex of anyone's, so far.

John, I was only trying to help with my understanding of what I thought you would get with your breeding of the two mexmex. Didn't mean to disagree with anything, just thought you'd get a lot of variety as opposed to the given patterns. We'll see what happens. Should be pretty whatever they are. Good luck with them.

Also, can't wait to see your next annulata. Would like to hunt for them someday too. Not this year though 'cus my trip to Idaho is already set now. Later...

TC

I wasn't trying to disagree with you. Maybe you are right about different patterns being morphs, but I have learned them to be phases in Thayeri.
I hope I do get some mexmex that show both traits, some that are light colored splitbanded and some that are dark phase normals.
I love variety within a single clutch. That is why I have bred Thayeri for the last 4 years and will never stop. Their genetics are great as is all of the Mexicana subspecies. Variability comes without needed "morphs" or "hets". I have bred alterna as well for a few years and like to see dark and light & blairs and alterna all out of a single clutch.
I think that is why Hondos and Brooksi are so popular. People enjoy breeding triple hets to triple hets and hatching all possible morphs. At least I think they do. LOL I do for sure.
Terry....I hope to find that Annulata male this Spring or Summer too. And I hope you can make it down for some Meahllmorum hunting as well.
Thanks for the compliment on the Mexmex pic.
John Lassiter

Without knowledge of their history, theres no telling what will come out.

I will say, in nature, you can and do find both these pattern types together. In fact when you said split band, I was interested because we found several that had their bands totally split completely down the back. Like the nuchel blotch on the male pictured.

When we first collected Tharys kings, most keyed out to be Mex-mex. Cheers FR

Thank you Frank,
I guess I will have some more sleepless nights with these and all my Thayeri hatching again.
Interesting that the nuchal stripes were all the way down the back. I have seen them at most 1/3 of the length of the snake.
I wish I could have been there in the day when Mexicana were collected.
Thanks again,
John Lassiter