Fish sex determination is REALLY weird.

[CT_]

There's a lot of anecdotes and some academic articles for well studied species about temperature and ph effecting sex in fish (and other animals), which I thought was weird enough. 

 

Medaka are famous for being a well studied model organism, and for being the first fish identified to have human-like sex genes (think XX for female vs XY for male).  But this article blew my mind and I hope some others find it interesting.

 

Quote

This study investigated whether irradiation of a specific light wavelength could affect the sex differentiation of fish. We first found that the photoreceptor genes responsible for receiving red, green, and ultraviolet light were expressed in the eyes of medaka during the sex differentiation period. Second, we revealed that testes developed in 15.9% of genotypic females reared under green light irradiation. These female-to-male sex-reversed fish (i.e. neo-males) showed male-specific secondary sexual characteristics and produced motile sperm. Finally, progeny tests using the sperm of neo-males (XX) and eggs of normal females (XX) revealed that all F1 offspring were female, indicating for the first time in animals that irradiation with light of a specific wavelength can trigger sex reversal.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382872/

[Fish Folk]

On 8/25/2021 at 3:36 PM, CT_ said:

There's a lot of anecdotes and some academic articles for well studied species about temperature and ph effecting sex in fish (and other animals), which I thought was weird enough. 

 

Medaka are famous for being a well studied model organism, and for being the first fish identified to have human-like sex genes (think XX for female vs XY for male).  But this article blew my mind and I hope some others find it interesting.

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382872/

Interesting! Here is another thread that might be worth noodling through.