Do you think he’ll go? And a discussion of genetic body size

Pythons Ball Pythons
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He’s dumping his water and laying inverted. I don’t have the heart to tell him that he won’t grow follicles no matter how hard he tries :rofl:

I’ve got a few snakes are genetically larger than average, and it’s something I play around with trying understand better through breeding. This male is 2700g. I have a Pastel Het Clown female that’s just shy of 4kg that I pair this snake with most years. Their babies are always 16-18” long at hatch and 80-85g at hatch.

I have another female het pied from Volta type lineage who is very large (~4200g). I’ve never paired her with a similarly large male like this guy but I plan to, to get a better understanding of how size is inherited. I’m aware that it comes from mitochondrial DNA. What I wonder is (and @t_h_wyman I’m sure knows a lot more about than I do) is size simply inherited or polygenic in BPs.

Taking last season as an example, large clown x large clown = all larger than average neonates. Large het pied x small leopard het pied yielded only two larger than average neonates both female.

It’s something I spend a fair amount of time considering, especially since hearing the ‘Genetic Round Table’ episode on MPR a few years ago, where Dr. Wyman elaborates on dwarfs vs pygmoids and how each is inherited.

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I have a 5500 gram female!!! She always lays big eggs her hatchlings are always bigger when born than any other females. All the eggs are incubated the same.

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Wow! I break IG every time I post 4kg females, I can only imaging having one that big! It’s crazy how complex seemingly simple things can be. My guess is that size is probably inherited in different ways like in retics but none of my breedings so far have given me concrete evidence (that i would recognize anyway) on how it works. Not going to lie, I started down this path because both of the big females I mentioned always lay 9-11 eggs and they’re always good sized eggs lol.

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She has laid clutches of 10,12, and 13 for me.

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That’s awesome. I got busy at work and forgot to order them a couple weeks ago, but outback had 5-6 gravid female volta types. A friend got one though and it laid 15 eggs!

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She is definitely the exception to the rule! I wish all my gals laid that many. She is a butter fire nothing crazy I bred her to my super sable vanilla this year. Hope she lays me a bunch of sable creams!!!

That’s awesome!!! You should try and get a couple females from him!!!

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That’s a great idea!

I’ve noticed certain genes seem to be associated with larger snakes. It seems like BEL maker females consistently get a good size. I’ve seen more XL mojave females than I have any other morph I can think of. Pastels, clowns, and some pieds also seem to be consistently larger when there aren’t a bunch of other morphs at play.

Conversely I have an Enchi female that at 8-9 years old never passes 2kg. Every year she goes like clockwork at the same time. She just doesn’t get the season to season growth most of my bigger girls do. Lays 7 eggs every single time.

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I have a few ladies doing that same thing and always take it as a good sign…

Wow 2700 grams for a male. I’ve only ever seen males lay inverted after a big meal that’s funny.

My biggest girl is a 3600 gram het gstripe, I can’t even imagine 5500! Although I have a female gargoyle that’s only 4.5yo and pushing 2800+ already, eats like a horse, she’s also 1 of the few females I have that continues feeding almost all the way until she lays.

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While it is true that mitochondria are predominantly inherited from the female and also that the female’s size can have an impact on offspring size, the mitochondria themselves do not play any role in size inheritance.
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Yes. Next question.

:rofl:

Okay, so, more seriously, polygenetic means that multiple genes are involved in the phenotype. So polygenetic traits are heritable, it is just a matter of whether you get all or some or none of the gene alleles involved in the phenotype.

Simple example - blood types. Everyone knows A, B, AB, and o and most people also know the ‘positive’ and ‘negative’ that goes with those, e.g., A-neg, AB-pos, etc. That ‘positive’ / ‘negative’ denotation is for Rh-factor, so technically A-neg is better written out as ARh- and AB-pos would be ABRh+. But in addition to those two fairly well known blood groups, there are another thirty-six groupings: Duffy, Kell, Kidd, Lewis, M, N…

Thus, blood type is polygenetic.

Now… Say you are A/Rh+/D-/K+/Ja/Lb/M-/N+

What are the odds that your offspring will share the identical blood type as you?

That is going to depend on two things:

  1. Your genotype
  2. Your mate and their genotype

Let us assign your genotype as: Ao/Rr/dd/KK/Jj/ll/mm/Nn

And your mate as: BB/rr/dd/kk/jj/Ll/MM/nn

Right away we can see that you can never have an offspring with your same blood type because your mate being BB means that all your offspring will be either phenotypically AB or B (also, your mate is MM and you are mm, so all of your offspring will be phenotypically M+)

Apply this same logic then to size. Say you need all eight of those genes to be homozygous to have an 8000g animal: AA/RR/dd/KK/JJ/ll/mm/NN

But… each gene pair, depending on inheritance pattern, still plays some small role in size. In this manner, even if your offspring does not get the perfect combination of gene pairs, it is still possible to get some of the right pairs and thus have some influence on size. So maybe they only hit 4000g instead of 8000g

And it should be at least somewhat obvious that pairing two phenotypically similar animals should then play a role in increasing the frequency of the genes behind those phenotypes coming together to maintain the phenotype.
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This is more a correlation than a causation thing. None of my Mojaves have ever broken 1500g for example

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Awesome explanation, thanks! It’s fascinating how much we both can and cannot control the genetics of these animals.

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