Male Maker and Female Maker Banana Ball Pythons Explained!


This is not just about the fact that male makers produce more male bananas and female makers produce more female bananas. We all knew that. But it makes no sense in a ZW system. Clint explains why we get male and female makers. This was the only thing in ball python genetics that didn’t make sense. Now it does!

Having read through the paper in its entirety, it is apparent that the authors were aware of the implications of their findings on the inheritance pattern for banana ball pythons, though they do not lay it out in its entirety in the text of the publication.

Some helpful information about ball python genetics:
Most of the traits in the ball python hobby are very simple. Some are dominant (which means that they look the same if they have one copy or two (from one parent or both). Some are recessive meaning you need two copies (one from each parent) to show the trait (those that have only one copy don’t show it. They are hets, which is short for heterozygous). The rest are incomplete dominant (often mistakenly called codominant in the hobby which is something else). Incomplete dominant traits look different if you have one copy (from one parent) than if you have two (from both parents).
Some examples: Pinstripe is dominant. Albino is recessive. Lesser/BEL is incomplete dominant.
Banana is incomplete dominant and linked to the sex determining chromosomes (X and Y).


Hey this is Clint, from Clint’s Reptile Videos and I apologize in advance because this video will not be up to our normal quality standards. The reason being what we’re about to share with you is something brand new. Something I have seen nowhere else. Something we just discovered for ourselves and you’re gonna be the first to hear about it. So we wanted to get this video out to you now, like right now, because this information is minutes old.

I was just recently pointed in the direction of a new paper that was published in Current Biology last month (Current Biology is a journal). It talks about the sex determination of ball pythons. Specifically, that they have XY sex determination, which is just like humans do except they evolved it independently. Why this is so exciting is because it makes sense of a great mystery in ball python genetics, and that is this snake right here.

This snake is a banana ball python. This thing is actually a banana pinstriped lesser ball python. One of the genes that makes it the most yellow is this banana gene and the banana gene is super weird. This banana here is a male and his father was a banana. Banana is inherited as an incomplete dominant trait. In the hobby, people will tell you it’s co-don or co-dominant but technically it’s really incomplete dominant. Which means that if you have two copies of this banana gene, you’re extra banana. More banana than one that only has one copy.

This may be over your heads a little bit for some of you, but for others who’ve really been wondering about this, this is going to make sense of everything about banana. So the weird thing about bananas is that I’ve got a male banana here whose father was a banana. Almost all of his offspring that have this banana trait will be males. He will produce almost no female offspring that are bananas. A female banana alternatively can produce male and female banana offspring, and the son of a female banana will produce almost entirely female bananas.

That has made almost no sense until now because previous to now we thought that ball pythons had a ZZZW inheritance pattern for sex determination. They don’t. They’re XY and that makes everything make sense. Because, this is not exactly the same as our XY. In humans for example the Y chromosome codes were very little. In ball pythons that y chromosome has to at least code for the gene that has this banana mutation on it, in addition to the X chromosome which also has it. In the case that I’ve got what you call a male maker banana, which is what mine is, he has that mutation on his Y chromosome. In order for him to, well for starters, he will pass that Y chromosome onto every single one of his sons.

The only case in which the Y chromosome, or sorry, the only case in which he would have a daughter with the banana mutation, is if a crossing over event occurred between the X and the y chromosome. Then he could produce a daughter with that banana mutation. A female would have it on her X chromosome and she could pass that x chromosome on to her sons and her daughters. So it makes perfect sense that she can produce both male and female banana offspring. A male banana that had a mother that was a banana would have the mutation on his x chromosome which he would pass on only to his daughters. The only case in which he would have a son with the banana mutation is if a crossing over event happened between the X and the y and the X now picked it up.

That makes sense of the world. Banana is on the x and y chromosomes and now male maker and female maker bananas make sense. I’m excited that I got to share this with you guys first. More to come on this.

More to come on ball pythons for sure and as always like and subscribe. Let us know what you thought, and we hope to see you real soon.