When breeding Banana x Banana Are the male non super bananas female makers?
I think it depends on if the male was a male maker or female maker.
If you had a female maker, all supers will be female, all normals will be male, regular bananas can be male or female. For the male maker case it will be flipped for normals/supers being male/female. The male regular bananas will be whatever male/female maker that the father is.
Below hopefully you can follow how I worked it out. (And check my work)
You cannot tell, at least not without breeding.
Think of it like this, if I do a Lesser x Lesser can I tell which know which parent donated the Lesser gene to any of the Lesser offspring?
But in the case of banana being on the sex chromosome, you actually can tell who donated the gene for male offspring. Male offspring can only inherit the male sex chromosome from the father (for animals with XY sex chromosomes).
I think there is some insanely rare possibility of the banana gene jumping between the pair of chromosomes through mutation, where you might get it wrong based off the sex.
Yes, it is sex-linked (and yes, it is the cross-over event that causes the low-frequency gender switch that is seen) but that does not change the scenario.
That said… If the sire is a male-maker then it is his Y chromosome that carries the mutation. In the dame the mutation is on the X chromosome. So, just by looking at any given male single-gene Banana in the clutch, you cannot tell whether it is carrying the Y from the sire or the X from the dame.
My statement stands, without breeding the animal out and seeing how it behaves, you cannot tell whether it is a male-maker or a female-maker.
The next argument someone will make is that is the sire is a female-maker then you would know. That is not correct either though, because the low-frequency cross-over event could generate a male-maker. As such, you again cannot guarantee single-gene males produced from the breeding are guaranteed as female-makers
What you’re saying was my initial gut feeling too, but when I worked it out I convinced myself that the single gene males will be whatever male/female maker that the father was.
Consider the example you gave above: If it is a single gene male offspring, and the original male has the banana gene on the Y chromosome, then the only Y chromosome that the offspring can get to make it a male is the Y chromosome from the original male with the banana gene on it. If it is a male in the same example and got the banana gene on an X chromosome then it has to be a super.
True though, you can never be 100% certain because a crossover mutation could happen, but it sounds like those are infrequent enough that you could be reasonably sure. Does anyone have data on this crossover mutation? How many out of 100 hatchlings come out with sex flipped from expected? Is it 10%, 1%, 0.1%?
If you run the numbers from what people have made public then you come up with a rate of around 8-10%
That’s really interesting that it happens that frequently! DNA replication stuff that encourages mutation/evolution is so cool!