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Colourful female guppies

Terry Ellacott

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When I started keeping fish all the guppies I had access to had females with no colour. The books I had then (now 40 years out of date) said the genes for colour were linked to the Y chromosome in guppies. 

Most of the strains I see now seem to have females with some color, "the best guppy in the world" strain has females which are more colourful than any males I've ever kept. 

Would I be correct in assuming that breeders have broken the link between the Y sex chromosome and the color genes? Can anyone point me in the right direction to find out more about this, both historically and the present situation? Thanks 

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@Terry Ellacott I believe your are correct!

I know everything I learned about biology has pretty much gone down the crapper* since I got my degree 25 years ago.

However, I think I read somewhere that because sex linked chromosomes typically evolve once recombination is halted, the transfer of genes between the two sex chromosomes is suppressed, but in guppies the male-heterogametic sex chromosome (Y) has shown little or no degradation.

This apparently allows for occasional recombination of guppy X and Y chromosomes which would explain why extremely colorful females are possible, but because of the rarity of this event it has taken decades to select for these colorful females.

In a nutshell guppy X and Y chromosome ain’t that different and very occasionally recombine during meiosis resulting in female guppies with male color genes.

I will search the literature and let you know if I find anything.

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