sex ratio of platy and swordtail hybrid

[xipo817]

One of my platy strain turned out to be male(YY) female(WY) type.(By sex linked inheritance of some trait ,I could figure this out.）
I want to cross this strain to albino kouhaku swordtail and gain albino (non-kouhaku) platy in F2 generation.
In this case is it wise to use female platy instead of male platy?
Because swordtail is said to have no sex chromosome and if YY male is crossed the sex ration would be very unbalanced.

 

[emeraldking]

I don't know where the info comes from that swordtails don't have sex chromosomes. Also swordtails have sex chromosomes. But the sex change works differently in swordtails than in platies. In platies, there are X, Y and W (this goes only for maculatus platies {Xiphophorus maculatus} and not other platy species that we know of). In most swordtails, there's just X and Y. Only a small percentage can be born with a W or Z sex chromosome (the Z sex chromosome only appears in males). Which makes it possible to have WZ-ZZ combinations.
In swordtails there is an autosomal locus with two alleles, A and a, which affects sex determination in XX fish. If the genotype is AA, the fish will be female, and if aa, the XX individual will be male. But when we have an Aa genotype specimen, the Aa genotype is predominantly female, but has the ability to change into a male.

When you look at current fancy platies and specifically those that also carry swordtails genes, it seems that most still have the sex chromosomes X, Y and W. And that most of such hybrids don't work in the same way of how it works in swordtails when it comes to sex chromosome combinations. So, it seems that the influence of the platy is stronger in the offspring than the influence of the swordtail in a crossbreed.

 

[xipo817]

Oh, thank you so much.
I 've read books that says swordtails changes sex in their lifespan, and somehow misunderstood that they don't have sex chromosomes(maybe the late Mr tsutsui said something like that).
I am surprised to hear that autosomal gene affects sex of swordtails.

 

[emeraldking]

Oh, thank you so much.
I 've read books that says swordtails changes sex in their lifespan, and somehow misunderstood that they don't have sex chromosomes(maybe the late Mr tsutsui said something like that).
I am surprised to hear that autosomal gene affects sex of swordtails.

There's also the phenomenon where old female swordtails will get elongated outer finrays. But this has got to do when she won't produce offspring anymore because of old age, a hormonal trigger will activate the MSX genes too much, which will cause morphological change in finnage. This will make an old female look like a male but there's no sex change. The bottom outer finrays of het caudal and the first finrays of her anal fin will elongate (but won't become a gonopodium). So, she'll remain a female.

 

[xipo817]

Today I found an interesting article saying that Rio Lancetilla strain X.helleri is ZW type.

Texas State collaboration identified new sex chromosome formation in swordtail fish

news.txstate.edu