Re:Why Sex? Biologists Find New Explanations
by nootropicat on Friday April 24, 2020 @09:59AM
(#22968000)
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.
Re:Why Sex? Biologists Find New Explanations
by dogma1138 on Saturday April 25, 2020 @06:11AM
(#22977064)
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
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.
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.