Saturday, April 25, 2009

Battle of the Sexes - i

Another change in neo-X that Bachtrog suspects is taking place is the elimination of genes that are harmful to females. Biologists have realized recently that some genes have opposite effects in males and females, and evolution is a tug of war between males jettisoning genes that they find detrimental only to have females put them back, and vice versa.

"A good place to put sexually antagonistic genes that are beneficial to one sex but detrimental to the other is on the sex chromosomes," she said. The Y always ends up in the male, she said, so genes on the Y chromosome won't affect females.
"Conversely, the X chromosome becomes feminized with genes that are good for the female but detrimental to the male," said Bachtrog, adding that the X also becomes demasculinized, losing genes that are of use only in the male.


Via Science Daily.

2 comments:

Maju said...

Hmmm... we men also have one X chromosome and in fact we could not live without it. X is only so much specifically female and actually a faulty X chromosome is much more likely to show its harmful side in males than in females, who can neutralize one with the other.

Not sure if I may be missing something but I am of the impression that X and therefore the female phenotype is the default one (in our species and other mammals), while Y is a modifying code, that turns a "basic" female model into an "altered" male variant. In fact people with XXY (and XXYY) syndrome are males (though often infertile or almost so), while XXX genotypes are female; so it is the Y the modifying element, while the female phenotype would be the default one.

Manjunat said...

I am of the impression that X and therefore the female phenotype is the default one (in our species and other mammals),Agree with you Maju.

They thought woman was created from man's rib. It was other way round. Man was created from woman's X-chromosome.