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MrinkysAnimalSide t1_jab5vz6 wrote

Temperature dependent sex determination is fascinating! Just remember, mammals and birds use chromosomal sex determination (meaning sex is genetic) but other mechanisms are quite common across all organisms! Check out the cool graphs at tree of sex http://treeofsex.org/.

There is still a lot of work left to be done on mechanisms of how temperature during incubation leads to different sex ratios. This is a good scientific review on red-eared sliders https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2695493/. The ultimate mechanisms, or why temperature sex determination occurs, is also an interesting evolutionary question. Here is a good starting point for further research: https://sites.utexas.edu/crewslab/files/2016/06/CrewsDVLGen.pdf.

Finally, it’s important to remember that sex is a complex phenotype with many components and is really a shorthand for biologists to describe a common suite of traits. But thanks to sweet, sweet variation there is no one size fits all! In fact, it’s not uncommon for sex to be broken down into at least 5 levels of animal sexuality but that’s just the beginning. Not to mention human-specific levels, such as gender. Just a fun aside, the genderbread person is a nice primer on gender https://www.genderbread.org/

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amador9 t1_jabcer8 wrote

No “y” chromosomes in fish?

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ke_marshall t1_jabe17i wrote

It depends on the species. Some have them, some don't: https://journals.plos.org/plosbiology/article/figures?id=10.1371/journal.pbio.1001899

My favorite fun fact is that sex determination in birds is exactly opposite to mammals: the females are heterogametic. They are ZW, while males are ZZ.

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MrinkysAnimalSide t1_jabfxzb wrote

It’s a great question and you’re exactly right! There are even some cases of fish having multiple sex chromosome systems interacting together to be XYZ. Cichlid fish in particular, well known for rapid speciation, show incredible evolution of sex chromosomes. In which case, you’re unlikely to find a single degenerate Y chromosome like you find in mammals.

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platoprime t1_jablhlw wrote

Why don't they use XY? Is it just alphanumeric numbering starting with the A chromosome? How do they pick the order of the chromosomes?

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lqstuart t1_jabmph1 wrote

https://en.wikipedia.org/wiki/X_chromosome

Tldr - they noticed the X chromosome was weird, so they called it X. Then Y was the next letter. Then Z and W came about to distinguish between the ZW system and the XY system (also it's important to note that the X chromosome is the X chromosome, period, whether it's in a mouse or a human or whatever--it refers to a specific thing that plays a specific role).

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Delirivms t1_jacmxfa wrote

So the band 'ZZ top' derives its meaning from homosexual birds?

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green_print_business t1_jac08xf wrote

>Why does temperature determine the sex of certain egg laying animals like crocodiles?

well explained . I have also go through the topic TSD. It is also true that a lot of work has left to be done on this mechanisms .

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