Banana

[Cajuputi]

Mike Wilbanks made a pretty good video explaining the genetics of bananas. You definitely have a chance to produce a banana spider male, 25% chance for that specific combo with it more than likely being male.

https://www.youtube.com/watch?v=71ZoSk0vGiY

Thank you for the nice link.

[Cajuputi]

You're correct that Banana is incomplete dominant, but Spider is still generally regarded as simple dominant... Even if one or two breeders have claimed that they produced a super form, it looks exactly like the heterozygous form making it "simple dominant". In my personal opinion, the fact that these purported "supers" are incredibly rare despite the popularity of the morph suggests that Spider is simple dominant and "homozygous lethal" in the majority of cases.

As for OP's question, Banana is sex-linked (when inherited from a male), but Spider is not sex-linked. Therefore, half of your banana offspring should be spiders. If anything, you have higher odds of producing male banana spiders rather than lower odds.

That sounds good to hear. I'd love spider banana

[Cajuputi]

If you pair your male you will have the chances of producing

25% Banana Spider
25% Banana
25% Spider
25% Normal

That is as far as mutations.

Now regarding the sex it will depends if you have a male maker or a female maker.

If you have a male maker the Banana and Banana Combos will be males and the rest females in the vast majority of the cases, however it's not always true Male makers can produce female Bananas or Banana combos on occasion.

Yeah, I've read the odds with male maker. If my male maker by low chance producing female banana. Would it be another female with male maker gene, or would it now be a normal female?

[Cajuputi]

In other words, you expect 50% males and 50% females. Of a male-maker's offspring, each male baby has a 25% chance of being normal, a 25% chance of being banana, a 25% chance of being spider, and a 25% chance of being banana spider. Each female baby has an approximately 49% chance of being normal and a 49% chance of being spider. There is a tiny chance of a female banana or female spider banana, but don't expect any.


Biochemically, codominant and incomplete dominant mutants act differently. At the level we are working at, we can't tell the difference. For simplicity, we lump both together under the term "codominant".

If homozygous spider is usually lethal before hatching, then spider is a codominant mutant gene. We call spider a dominant mutant gene because it is not a recessive mutant gene and we are unsure whether it is a full dominant or a codominant (or one of the other types of less than fully dominant mutants).


I am pretty sure that neither the spider nor the banana mutant gene is sexlinked. If banana was sexlinked, a male banana's female offspring would be 50% banana. I don't think anyone has figured out the reason for male-makers and female makers.

I have wondered. If a male-maker banana male is mated to a normal female, are there statistically more males than females? Or are the males and females approximately equal in number?

I like the way you explain things. Although I still don't really understand the last paragraph about sex linked gene.

[OhhWatALoser]

Perhaps Paul could add to this but from what I understand, Sex chromosomes in snakes are known to be Z and W. Males are ZZ and females are ZW (opposite of the human XY male and XX female). so when a male breeds to a female, you can get 1 of 2 Z chromosomes from the male and either another Z or a W from the female. So a simple sex linked gene will either be linked to Z or W

W linked gene is the easiest, only females can have it, any female produced from a female who has it will also have it. Male will never have it, ever.
Z linked gene females can have the heterozygous and males can have both heterozygous and homozygous. Females who have it will produce females without it and males with it. Heterozygous male will throw normal ratio. Homozygous male will throw normal ratio. Homozygous male to heterozygous female will only throw super males and heterozygous females.

Now bananas on the other hand.... well are doing something never seen before. They kinda act sex linked as we have males that throw skewed ratios and the whole 10% of the time bananas throw the opposite sex thing could be explained by crossing over, which does happen, but the big monkey wrench is as with my above example it should be expected that females would be the ones throwing skewed ratios, not males. the gene is acting like a XY sex linked gene with crossing over and not a ZW. So we could blindly say ball pythons are XY. As far as I know ZW has not been identified in ball pythons.

However ZW has been identified in burms and we know ball pythons breed fine with burms. As far as I know there has never been a snake found to have XY and I don't even know of a reptile that is XY however I never looked that deep either. Basically from the dinosaur era and before, snakes have been ZW. There are reptiles that determine sex through other means such as temperature, but if there is identifiable sex chromosomes it has always been ZW as far as I know. So long story short, if we call it sex linked we are suggesting that ball pythons are XY after having an enormous line of ZW ancestors and a ZW close relative (burms) that they can reproduce with, solely based on the evidence of a gene. I think it is pretty short sighted to make that leap.

So when people ask about banana being sex linked, I say the evidence currently doesn't support that. When talking about genetics and referring to sex linked genes, people expect the above scenarios, so even saying it is not sex linked isn't really wrong lingo wise. However someday maybe someone can possible figure out the riddle and maybe the gene actually does reside on a sex chromosome, but it would be a special case with the abnormalities surrounding it.

[paulh]

To expand a bit on OhWatALoser wrote:

In the normal type of sexlinkage, our malemaker banana royal python has two Z chromosomes (ZZ). One Z has the banana gene, and the other has the corresponding normal gene. We can symbolize this as ZZ. The red Z has the banana gene, and the black Z has the normal gene. This male is mated to a normal female with the ZW chromosome pair. Both the Z and W are in black. The Z chromosome has the normal gene, and the W has either the normal gene or no corresponding gene.

A ZZ male is mated to a ZW female. In a fertilized egg, the male's normal Z chromosome pairs with either the female's Z or the female's W chromosome. The male's Z chromosome can also pair with either the female's Z or the female's W chromosome. This produces 4 possible chromosome pairs:
ZZ = banana male
ZZ = normal male
ZW = banana female
ZW = normal female

We expect about half of the bananas to be females. But according to Mike Wilbanks, only about 10% of the bananas from this mating are females. Why the excess of male bananas? We can only conclude that something unexpected is going on.

[Stewart_Reptiles]

Yeah, I've read the odds with male maker. If my male maker by low chance producing female banana. Would it be another female with male maker gene, or would it now be a normal female?

Female Bananas or CG produce normal sex ratios.

When it comes to males, a male from Banana or CG sire will be a male maker. A male from a Banana or CG Dam will be a female maker.

[For Goodness Snakes]

I've never bred snakes, but the information is out there to be found. Banana and Spider are both co-dominant genes, rather than recessive. Pied is an example of a recessive. So if you bred a Pied snake to a snake that was neither Pied nor het. for Pied, you would get het. Pied offspring. Not visible Pied offspring. But because Banana and Spider are co-dominant genes, the offspring could be banana, spider, normal, or banana-spider. There's no way to know for certain until the eggs hatch, basically. You could end up with all banana-spiders if you get really lucky - or you could end up with all normals, if you're really unlucky. Both of those are possible outcomes, but pretty unlikely. Most likely, you would get a mixture of offspring. It's a random shot, and there's really no way to control it. Even if you had two Bananas and bred them together, there's the possibility of normals. I think the only way to guarantee that the offspring will have a co-dominant gene in them is to have a parent with the super form of the gene, so that you know the offspring will get a copy of it - for example, if you had a Super Banana, you'd be assured that all the hatchlings would, at the least, be Banana.

There are others around who know far more about breeding snakes than I do - hopefully they'll chime in if I've got anything wrong, and correct me!

Actually a spider is a dominant gene trait not a co-dominant.

Brian

[Eric Alan]

Actually a spider is a dominant gene trait not a co-dominant.

Brian

Depending on your school of thought, it could be considered incomplete dominant with the super form being a dead white snake.

[OhhWatALoser]

Actually a spider is a dominant gene trait not a co-dominant.

Brian

There's nothing to suggest it is a dominant gene besides it's misclassification being repeated and rumors of super spiders that never seem to be able to prove themselves