3 ms·

This isn’t about sex chromosomes, we have 1000’s of genes that are sex-biased this means that their expression is dependent on sex. The level of bias isn’t eve

This isn’t about sex chromosomes, we have 1000’s of genes that are sex-biased this means that their expression is dependent on sex. The level of bias isn’t even solely dependent on the gene in question but on much more complex mechanisms that are frankly not well understood for example in humans testicles and mammary glands have some of the highest levels of sex biased expression in of all tissues. Other tissues like brain, heart and muscles also have variance but to overall lower levels (higher brain tissue expression variance in males for example has been linked to higher likelihood of schizophrenia and other mental conditions). Overall males it seems that there is a higher variances of sex biased gene expression in various tissues compared to females. This means that it goes beyond we have a backup X chromosome and gene deactivation escape mechanisms. Gene expression variance can explain why males might a higher overall variance in traits.

nootropicat 7y ago
The existence of those mechanisms doesn't mean the increased variance from only one X chromosome disappears - for males to have equal variance the increase from just one X would have to be compensated somehow, which is probably impossible given how directly important X is - the needed information is gone.
- dogma1138 7y ago
  What I’m saying is that genetic variance and gene expression variance aren’t the same thing. In fact in males there is a phenomenon that is called feminization of gene expression where by removing sexual competition causes gene feminization in males causing the population to more favorably express female bias. https://www.nature.com/articles/ncomms4482 https://www.nature.com/articles/ncomms4482 I can’t find the study now but similar results have been reported in humans especially in sperm and testicular tissue that begin experiencing gene expression feminization rather quickly in monogamous relationships.

nootropicat 7y ago

The existence of those mechanisms doesn't mean the increased variance from only one X chromosome disappears - for males to have equal variance the increase from just one X would have to be compensated somehow, which is probably impossible given how directly important X is - the needed information is gone.

dogma1138 7y ago
What I’m saying is that genetic variance and gene expression variance aren’t the same thing. In fact in males there is a phenomenon that is called feminization of gene expression where by removing sexual competition causes gene feminization in males causing the population to more favorably express female bias. https://www.nature.com/articles/ncomms4482 https://www.nature.com/articles/ncomms4482 I can’t find the study now but similar results have been reported in humans especially in sperm and testicular tissue that begin experiencing gene expression feminization rather quickly in monogamous relationships.